Yagmur Denizhan | Bogazici University (original) (raw)

Papers by Yagmur Denizhan

Research paper thumbnail of Simulated Education and Illusive Technologies

The Future Information Society, 2017

Research paper thumbnail of Evolution of the mental model: From archaic myths to modern myths

Biosystems, 2020

3-D web browsing is a promising trend for interaction with web content. However it is still illus... more 3-D web browsing is a promising trend for interaction with web content. However it is still illusive between virtual reality applications on the one side, and conventional web browsing on the other. In this research we propose a new model for 3-D web browsing that capitalizes on features of virtual reality technology with those of conventional browsing in order to provide an enhanced interactive user experience with web content. The new model is based on representing information content elements in 3-D perspective and organizing them inside a 3-D container that we call a "Web Cube" for 3-D web browsing. Furthermore, the model defines appropriate interaction mechanisms based on hand gestures. The model has been evaluated using an experimental technique to evaluate its efficiency, and a questionnaire to evaluate user satisfaction.

Research paper thumbnail of An Implementation of Fuzzy and Classical Control Methods on a D.C. Motor

IFAC Proceedings Volumes, 1992

The equivalence of linear incremental fuzzy control and linear PI control and the equivalence of ... more The equivalence of linear incremental fuzzy control and linear PI control and the equivalence of non linear incremental fuzzy control and nonlinear PI control have already been proven. The experimental outcomes obtained from the microcomputer-based control of a D.C. serva motor verify the theoretical results. I.INTRODUCTlON

Research paper thumbnail of Roots of the Contemporary Mental Model in Ancient Mythology

The American Journal of Semiotics, 2008

Research paper thumbnail of Improvement of neural network based targeting via clustering in higher-dimensional chaotic systems

Physics Letters A, 2004

In this Letter, an improvement in the previously proposed extended control regions (ECR) method i... more In this Letter, an improvement in the previously proposed extended control regions (ECR) method is presented, which gives better performance with respect to average reaching time. The performances of both ECR methods have been compared on basis of simulation results obtained for several low-and high-dimensional chaotic systems.

Research paper thumbnail of Classification trees prove useful in nondestructive testing of spot weld quality

Welding Journal (Miami);(United …, 1993

Until recently, the principal technique used to test spot welds on assembly lines has been destru... more Until recently, the principal technique used to test spot welds on assembly lines has been destructive testing. With industries becoming more cost competitive, manufacturers have looked for alternatives to destructive testing. One alternative that has enjoyed some success in recent years is ...

Research paper thumbnail of An improved neural network based targeting method for chaotic dynamics

Chaos, Solitons & Fractals, 2003

In this study, an improvement in the previously proposed Extended Control Regions (ECR) method [P... more In this study, an improvement in the previously proposed Extended Control Regions (ECR) method [Physica D 150 (2001) 163] is presented, which gives better performance with respect to training time and average reaching time while maintaining the advantages of the previous method. In the improved approach, the system data is first pre-processed and subdivided into clusters, and then one artificial

Research paper thumbnail of Improvement of Targeting Efficiency in Chaos Control Using Clustering

AIP Conference Proceedings, 2002

In this paper an improved version of the previously presented ECR (Extended Control Regions) targ... more In this paper an improved version of the previously presented ECR (Extended Control Regions) targeting method is proposed, where the system data is first pre-processed and subdivided into clusters, and then one artificial neural network is assigned to each such cluster. Furthermore, an analytical criterion for determining the region of the current system state during targeting is introduced, whereas in

Research paper thumbnail of In Search of a Reconciliation Between Semiotics, Thermodynamics and Metasystem Transition Theory

Axiomathes, 2005

ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary ... more ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary processes quite independently from each other. The aim of this paper is to draw the parallels and point out the possibility and necessity of a rec-onciliation between these disciplines. ...

Research paper thumbnail of Evolution of the “window”

Sign Systems Studies, 2002

We propose a general model that integrates meta-system transition theory with biosemiotics on the... more We propose a general model that integrates meta-system transition theory with biosemiotics on the basis of an “evolvable window” metaphor. The evolution of the “window” proceeds via meta-system transitions, during which new windows are created iteratively on the “inner” side of the preexisting ones, generating a “telescope” growing inwards starting from the “outside”. The tendency of “inwards growth” of the “telescope” can be explained in terms of the following circular causality: (1) the tendency leading from unity towards individualisation, (2) individual learning providing a basis for more complex semiotic interactions, (3) creation of additional, nonconflicting “values” leading to habit formation, (4) strong control bringing forth a unification at a higher (meta-system) level. Using the proposed metaphor we hope to provide clarity to the fluctuation between objectivity and subjectivity inherent to the circular causality loop described above.

Research paper thumbnail of Chaos control via neural networks using radial basis functions

AIP Conference Proceedings, 2000

Research paper thumbnail of The Endomembrane System: A Representation of the Extracellular Medium?

Research paper thumbnail of Chaos control via neural networks using radial basis functions

AIP Conference Proceedings, 2000

Abstract. In this work, a targeting method to be used together with the local OGY control is sugg... more Abstract. In this work, a targeting method to be used together with the local OGY control is suggested. In order to reduce the typical drawback of the OGY control, ie the long duration usually required for a chaotic system to reach the close neighbourhood of the chosen target –an ...

Research paper thumbnail of Roots of the Contemporary Epistemological Model in Mesopotamian Mythology

This paper asserts that the mental model of a social system is shaped by the conditions at the ti... more This paper asserts that the mental model of a social system is shaped by the conditions at the time when the society gains its identity and unity, and its basic traits are maintained to a great extent through the subsequent social evolution. Based on this assumption, some basic traits of the epistemological system of today’s civilisation are expected to have their origins in the mental model of early agricultural societies. Various Mesopotamian myths are analysed to identify the roots of some fundamental epistemological problems of the contemporary society. Résumé Ce texte éxplique que le modèle mental d'un système social est formé par les conditions qui prévalent au moment où la société acquiert son identité et son unité, et ses traits fondamentaux sont maintenus à une grande échelle par l'évolution sociale subséquente. D'après cette supposition, quelques traits fondamentaux du système épistémologique de la civilisation contemporaine sont censés avoir leurs origines dan...

Research paper thumbnail of In Search of a Reconciliation Between Semiotics, Thermodynamics and Metasystem Transition Theory

Axiomathes, 2005

The disciplines of cybernetics, semiotics and thermodynamics investigate evolutionary processes q... more The disciplines of cybernetics, semiotics and thermodynamics investigate evolutionary processes quite independently from each other. The aim of this paper is to draw the parallels and point out the possibility and necessity of a reconciliation between these disciplines. The concept of metasystem transition has been proposed by Turchin as a quantum of evolution from a cybernetic point of view. Semiotic processes are of prime importance for the realisation of metasystem transitions in the course of evolution. From a thermodynamic point of view, the emergence of more complex, self-producing agents depends on the emergence of more advanced forms of semiosis. As an evolutionary consequence, more symbolic forms of semiosis that allow higher competence for abstraction and anticipation emerge.

Research paper thumbnail of The non-decreasing character of complexity: A biological approach

Proceedings of the Third International Conference on …, 1999

Research paper thumbnail of Long-term mathematical model involving renal sympathetic nerve activity, arterial pressure, and sodium excretion

Annals of biomedical …, 2005

This paper presents a physiological long-term model of the cardiovascular system. It integrates t... more This paper presents a physiological long-term model of the cardiovascular system. It integrates the previous models developed by Guyton, Uttamsingh and Coleman. Additionally it introduces mechanisms of direct effects of the renal sympathetic nerve activity (rsna) on tubular sodium reabsorption and renin secretion in accordance with experimental data from literature. The resulting mathematical model constitutes the first long-term model of the cardiovascular system accounting for the effects of rsna on kidney functions in such detail. The objective of developing such a model is to observe the consequences of long-term rsna increase and impairment of rsna inhibition under volume loading. This model provides an understanding of the rsna-related mechanisms, which cause mean arterial pressure increase in hypertension and total sodium amount increase (sodium retention) in congestive heart failure, nephrotic syndrome and cirrhosis.

Research paper thumbnail of Control of chaotic systems using targeting by extended control regions method

Physica D: Nonlinear Phenomena, 2001

In this work, the previously proposed extended control regions (ECR) algorithm for targeting is i... more In this work, the previously proposed extended control regions (ECR) algorithm for targeting is improved by using individual neural networks for each activation region. The improved version, which exploits the short time predictability of the chaotic system more efficiently, gives better performance with respect to training time and average reaching time while maintaining the advantages of the previous method. Moreover, the simulation results revealed that the meaningful number of activation regions of the controller using improved ECR is nearly linearly related with the prediction horizon of the chaotic system to be targeted, which can be used as a criterion for choosing the number of activation region.

Research paper thumbnail of Roots of the Contemporary Mental Model in Ancient Mythology

The American Journal of Semiotics, Donald Favareau (guest-ed.), Volume 24.1-3 (2008), pp. 145-158, Philosophy Documentation Center, Virginia USA., 2008

Research paper thumbnail of In search of a reconciliation between semiotics, thermodynamics and metasystem transition theory

Axiomathes, 2005

ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary ... more ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary processes quite independently from each other. The aim of this paper is to draw the parallels and point out the possibility and necessity of a rec-onciliation between these disciplines. ...

Research paper thumbnail of Simulated Education and Illusive Technologies

The Future Information Society, 2017

Research paper thumbnail of Evolution of the mental model: From archaic myths to modern myths

Biosystems, 2020

3-D web browsing is a promising trend for interaction with web content. However it is still illus... more 3-D web browsing is a promising trend for interaction with web content. However it is still illusive between virtual reality applications on the one side, and conventional web browsing on the other. In this research we propose a new model for 3-D web browsing that capitalizes on features of virtual reality technology with those of conventional browsing in order to provide an enhanced interactive user experience with web content. The new model is based on representing information content elements in 3-D perspective and organizing them inside a 3-D container that we call a "Web Cube" for 3-D web browsing. Furthermore, the model defines appropriate interaction mechanisms based on hand gestures. The model has been evaluated using an experimental technique to evaluate its efficiency, and a questionnaire to evaluate user satisfaction.

Research paper thumbnail of An Implementation of Fuzzy and Classical Control Methods on a D.C. Motor

IFAC Proceedings Volumes, 1992

The equivalence of linear incremental fuzzy control and linear PI control and the equivalence of ... more The equivalence of linear incremental fuzzy control and linear PI control and the equivalence of non linear incremental fuzzy control and nonlinear PI control have already been proven. The experimental outcomes obtained from the microcomputer-based control of a D.C. serva motor verify the theoretical results. I.INTRODUCTlON

Research paper thumbnail of Roots of the Contemporary Mental Model in Ancient Mythology

The American Journal of Semiotics, 2008

Research paper thumbnail of Improvement of neural network based targeting via clustering in higher-dimensional chaotic systems

Physics Letters A, 2004

In this Letter, an improvement in the previously proposed extended control regions (ECR) method i... more In this Letter, an improvement in the previously proposed extended control regions (ECR) method is presented, which gives better performance with respect to average reaching time. The performances of both ECR methods have been compared on basis of simulation results obtained for several low-and high-dimensional chaotic systems.

Research paper thumbnail of Classification trees prove useful in nondestructive testing of spot weld quality

Welding Journal (Miami);(United …, 1993

Until recently, the principal technique used to test spot welds on assembly lines has been destru... more Until recently, the principal technique used to test spot welds on assembly lines has been destructive testing. With industries becoming more cost competitive, manufacturers have looked for alternatives to destructive testing. One alternative that has enjoyed some success in recent years is ...

Research paper thumbnail of An improved neural network based targeting method for chaotic dynamics

Chaos, Solitons & Fractals, 2003

In this study, an improvement in the previously proposed Extended Control Regions (ECR) method [P... more In this study, an improvement in the previously proposed Extended Control Regions (ECR) method [Physica D 150 (2001) 163] is presented, which gives better performance with respect to training time and average reaching time while maintaining the advantages of the previous method. In the improved approach, the system data is first pre-processed and subdivided into clusters, and then one artificial

Research paper thumbnail of Improvement of Targeting Efficiency in Chaos Control Using Clustering

AIP Conference Proceedings, 2002

In this paper an improved version of the previously presented ECR (Extended Control Regions) targ... more In this paper an improved version of the previously presented ECR (Extended Control Regions) targeting method is proposed, where the system data is first pre-processed and subdivided into clusters, and then one artificial neural network is assigned to each such cluster. Furthermore, an analytical criterion for determining the region of the current system state during targeting is introduced, whereas in

Research paper thumbnail of In Search of a Reconciliation Between Semiotics, Thermodynamics and Metasystem Transition Theory

Axiomathes, 2005

ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary ... more ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary processes quite independently from each other. The aim of this paper is to draw the parallels and point out the possibility and necessity of a rec-onciliation between these disciplines. ...

Research paper thumbnail of Evolution of the “window”

Sign Systems Studies, 2002

We propose a general model that integrates meta-system transition theory with biosemiotics on the... more We propose a general model that integrates meta-system transition theory with biosemiotics on the basis of an “evolvable window” metaphor. The evolution of the “window” proceeds via meta-system transitions, during which new windows are created iteratively on the “inner” side of the preexisting ones, generating a “telescope” growing inwards starting from the “outside”. The tendency of “inwards growth” of the “telescope” can be explained in terms of the following circular causality: (1) the tendency leading from unity towards individualisation, (2) individual learning providing a basis for more complex semiotic interactions, (3) creation of additional, nonconflicting “values” leading to habit formation, (4) strong control bringing forth a unification at a higher (meta-system) level. Using the proposed metaphor we hope to provide clarity to the fluctuation between objectivity and subjectivity inherent to the circular causality loop described above.

Research paper thumbnail of Chaos control via neural networks using radial basis functions

AIP Conference Proceedings, 2000

Research paper thumbnail of The Endomembrane System: A Representation of the Extracellular Medium?

Research paper thumbnail of Chaos control via neural networks using radial basis functions

AIP Conference Proceedings, 2000

Abstract. In this work, a targeting method to be used together with the local OGY control is sugg... more Abstract. In this work, a targeting method to be used together with the local OGY control is suggested. In order to reduce the typical drawback of the OGY control, ie the long duration usually required for a chaotic system to reach the close neighbourhood of the chosen target –an ...

Research paper thumbnail of Roots of the Contemporary Epistemological Model in Mesopotamian Mythology

This paper asserts that the mental model of a social system is shaped by the conditions at the ti... more This paper asserts that the mental model of a social system is shaped by the conditions at the time when the society gains its identity and unity, and its basic traits are maintained to a great extent through the subsequent social evolution. Based on this assumption, some basic traits of the epistemological system of today’s civilisation are expected to have their origins in the mental model of early agricultural societies. Various Mesopotamian myths are analysed to identify the roots of some fundamental epistemological problems of the contemporary society. Résumé Ce texte éxplique que le modèle mental d'un système social est formé par les conditions qui prévalent au moment où la société acquiert son identité et son unité, et ses traits fondamentaux sont maintenus à une grande échelle par l'évolution sociale subséquente. D'après cette supposition, quelques traits fondamentaux du système épistémologique de la civilisation contemporaine sont censés avoir leurs origines dan...

Research paper thumbnail of In Search of a Reconciliation Between Semiotics, Thermodynamics and Metasystem Transition Theory

Axiomathes, 2005

The disciplines of cybernetics, semiotics and thermodynamics investigate evolutionary processes q... more The disciplines of cybernetics, semiotics and thermodynamics investigate evolutionary processes quite independently from each other. The aim of this paper is to draw the parallels and point out the possibility and necessity of a reconciliation between these disciplines. The concept of metasystem transition has been proposed by Turchin as a quantum of evolution from a cybernetic point of view. Semiotic processes are of prime importance for the realisation of metasystem transitions in the course of evolution. From a thermodynamic point of view, the emergence of more complex, self-producing agents depends on the emergence of more advanced forms of semiosis. As an evolutionary consequence, more symbolic forms of semiosis that allow higher competence for abstraction and anticipation emerge.

Research paper thumbnail of The non-decreasing character of complexity: A biological approach

Proceedings of the Third International Conference on …, 1999

Research paper thumbnail of Long-term mathematical model involving renal sympathetic nerve activity, arterial pressure, and sodium excretion

Annals of biomedical …, 2005

This paper presents a physiological long-term model of the cardiovascular system. It integrates t... more This paper presents a physiological long-term model of the cardiovascular system. It integrates the previous models developed by Guyton, Uttamsingh and Coleman. Additionally it introduces mechanisms of direct effects of the renal sympathetic nerve activity (rsna) on tubular sodium reabsorption and renin secretion in accordance with experimental data from literature. The resulting mathematical model constitutes the first long-term model of the cardiovascular system accounting for the effects of rsna on kidney functions in such detail. The objective of developing such a model is to observe the consequences of long-term rsna increase and impairment of rsna inhibition under volume loading. This model provides an understanding of the rsna-related mechanisms, which cause mean arterial pressure increase in hypertension and total sodium amount increase (sodium retention) in congestive heart failure, nephrotic syndrome and cirrhosis.

Research paper thumbnail of Control of chaotic systems using targeting by extended control regions method

Physica D: Nonlinear Phenomena, 2001

In this work, the previously proposed extended control regions (ECR) algorithm for targeting is i... more In this work, the previously proposed extended control regions (ECR) algorithm for targeting is improved by using individual neural networks for each activation region. The improved version, which exploits the short time predictability of the chaotic system more efficiently, gives better performance with respect to training time and average reaching time while maintaining the advantages of the previous method. Moreover, the simulation results revealed that the meaningful number of activation regions of the controller using improved ECR is nearly linearly related with the prediction horizon of the chaotic system to be targeted, which can be used as a criterion for choosing the number of activation region.

Research paper thumbnail of Roots of the Contemporary Mental Model in Ancient Mythology

The American Journal of Semiotics, Donald Favareau (guest-ed.), Volume 24.1-3 (2008), pp. 145-158, Philosophy Documentation Center, Virginia USA., 2008

Research paper thumbnail of In search of a reconciliation between semiotics, thermodynamics and metasystem transition theory

Axiomathes, 2005

ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary ... more ABSTRACT. The disciplines of cybernetics, semiotics and thermodynamics inves-tigate evolutionary processes quite independently from each other. The aim of this paper is to draw the parallels and point out the possibility and necessity of a rec-onciliation between these disciplines. ...