Browsing by Subject "Modelling"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Open Access Animation of deformable models(Pergamon Press, 1994) Güdükbay, Uğur; Özgüç, B.Although kinematic modelling methods are adequate for describing the shapes of static objects, they are insufficient when it comes to producing realistic animation. Physically based modelling remedies this problem by including forces, masses, strain energies and other physical quantities. The paper describes a system for the animation of deformable models. The system uses physically based modelling methods and approaches from elasticity theory for animating the models. Two different formulations, namely the primal formulation and the hybrid formulation, are implemented so that the user can select the one most suitable for an animation depending on the rigidity of the models. Collision of the models with impenetrable obstacles and constraining of the model points to fixed positions in space are implemented for use in the animations. © 1994.Item Open Access Architecture framework for mapping parallel algorithms to parallel computing platforms(CEUR-WS, 2013) Tekinerdogan, Bedir; Arkin, E.Mapping parallel algorithms to parallel computing platforms requires several activities such as the analysis of the parallel algorithm, the definition of the logical configuration of the platform, and the mapping of the algorithm to the logical configuration platform. Unfortunately, in current parallel computing approaches there does not seem to be precise modeling approaches for supporting the mapping process. The lack of a clear and precise modeling approach for parallel computing impedes the communication and analysis of the decisions for supporting the mapping of parallel algorithms to parallel computing platforms. In this paper we present an architecture framework for modeling the various views that are related to the mapping process. An architectural framework organizes and structures the proposed architectural viewpoints. We propose five coherent set of viewpoints for supporting the mapping of parallel algorithms to parallel computing platforms. We illustrate the architecture framework for the mapping of array increment algorithm to the parallel computing platform. Copyright © 2013 for the individual papers by the papers' authors.Item Open Access Concepts and analysis in facility location under uncertainty : applications to 1-median problem(Bilkent University, 2001-08) Demir, Muhittin HakanItem Open Access A conceptual model for public relations in museums(Emerald Publishing Limited, 2010) Gürel, E.; Kavak, B.Purpose: This paper aims to present a conceptual model for public relations specific to museums. Design/methodology/approach: Based on relevant literature, a contingency model is developed for the public relations practices of museums. Findings: The model offers the market orientation level of the management and the interest level of the publics as the major factors that influence the effectiveness of the public relations programs in museums. The interest level of the publics is offered as a moderating variable. Practical implications: The model suggests that the effectiveness of the public relations programs of museums depends on two major factors. Although the interest level of the publics may seem to be uncontrollable at first glance, its negative impact can be largely controllable by managers by changing their own market orientation level - by adapting the public relations strategy to the targeted public depending on the interest level of that public. Originality/value: The model is specifically designed for museums. It can be accepted as the first public relations model specifically offered for museums. The model here recognises the relationship between marketing and public relations.Item Open Access A coupled model for healthy and cancerous cells dynamics in Acute Myeloid Leukemia(IFAC, 2014) Avila, J. L.; Bonnet, C.; Özbay, Hitay; Clairambault, J.; Niculescu, S. I.; Hirsch, P.; Delhommeau, F.In this paper we propose a coupled model for healthy and cancerous cell dynamics in Acute Myeloid Leukemia. The PDE-based model is transformed to a nonlinear distributed delay system. For an equilibrium point of interest, necessary and sufficient conditions of local asymptotic stability are given. Simulation examples are given to illustrate the results.Item Open Access An investigation of the effects of human dynamics on system stability and performance(Bilkent University, 2018-08) Yousefi, EhsanConsidered as a challenging element of closed-loop structures, the human operator, and his/her interactions with the underlying system, should be carefully analyzed to obtain a safe and high performing system. In this thesis, the interaction between human dynamics and the closed loop system is investigated for two different scenarios. The first scenario consists of a ight control system controlled by an adaptive controller. A telerobotic system where the controllers are conventional linear controllers is analyzed in the second scenario. Although model reference adaptive control (MRAC) offers mathematical design tools to effectively cope with many challenges of the real world control problems such as exogenous disturbances, system uncertainties, and degraded modes of operations, when faced with human-in-the-loop settings, these controllers can lead to unstable system trajectories in certain applications. To establish an understanding of stability limitations of MRAC architectures in the presence of humans, a mathematical framework is developed for the first scenario, whereby an MRAC is designed in conjunction with a class of linear human models including human reaction delays. This framework is then used to reveal, through stability analysis tools, the stability limit of the MRAC-human closed loop system and the range of model parameters respecting this limit. An illustrative numerical example of an adaptive ight control application with a Neal-Smith pilot model is utilized to demonstrate the effectiveness of the developed approaches. The effect of a linear filter, inserted between the human model and MRAC, on the closed loop stability is also investigated. Related to this, a mathematical approach to study how the error dynamics of MRAC could favorably or unfavorably in uence human operator's error dynamics in performing a certain task is analyzed. An illustrative numerical example concludes the study. For the second scenario, stability properties of three different human-in-the-loop telerobotic system architectures are comparatively investigated, in the presence of human reaction time-delay and communication time-delays. The challenging problem of stability characterization of systems with multiple time-delays is addressed by implementing rigorous stability analysis tools, and the results are verified via numerical illustrations. Practical insights about the results of the stability investigations are also provided. Finally, apart from these scenarios, after the observation that a simple linear transfer function model for a real force re ecting haptic device, which is used in telerobotics applications, is missing, a data-driven and first principles modeling of the Geomagic® Touch™ (formerly PHANToM® Omni® ) haptic device is considered. A simple linear model is provided for one of the degrees of freedom based on fundamental insights into the device structure and in light of experimental observations.Item Open Access Modelling detailed information flows in building design with the parameter-based design structure matrix(Elsevier, 2006-01) Tasli Pektas, S.; Pultar M.The Architecture/Engineering/Construction (AEC) industry is one of the multidisciplinary domains in which collaboration among related parties is of utmost importance. Despite the intense flow of information between design professionals, there is a lack of research to better understand and manipulate these flows. Most of the current process modelling tools in the AEC industry do not enable analyses of iterative information cycles. Moreover, these tools represent the process at high levels, thus, they are inadequate for multi-parameter problems like building design. With a view to alleviate these problems, this paper introduces the use of parameter-based design structure matrix as a process modelling and system analysis tool for building design. The method reveals insights into the process structure, optimum sequence of parameter decisions, iterative cycles and concurrency in the process. The application of the method is demonstrated through a case study on suspended ceiling design in a real-life project.Item Open Access A new model of cell dynamics in Acute Myeloid Leukemia involving distributed delays(2012) Avila, J. L.; Bonnet, C.; Clairambault, J.; Özbay, Hitay; Niculescu, S. I.; Merhi, F.; Tang, R.; Marie, J. P.In this paper we propose a refined model for the dynamical cell behavior in Acute Myeloid Leukemia (AML) compared to (Özbay et al, 2012) and (Adimy et al, 2008).We separate the cell growth phase into a sequence of several sub-compartments. Then, with the help of the method of characteristics, we show that the overall dynamical system of equations can be reduced to two coupled nonlinear equations with four internal sub-systems involving distributed delays. © 2012 IFAC.Item Open Access Quercetin/β-cyclodextrin inclusion complex embedded nanofibres: slow release and high solubility(Elsevier, 2016-04) Aytac Z.; Kusku, S. I.; Durgun, Engin; Uyar, TamerElectrospinning of polyacrylic acid (PAA) nanofibres (NF) incorporating β-cyclodextrin inclusion complex (β-CD-IC) of quercetin (QU) was performed. Here, β-CD was used as not only the crosslinking agent for PAA nanofibres but also as a host molecule for inclusion of QU. The phase solubility test showed enhanced solubility of QU due to the inclusion complexation; in addition, the stoichiometry of QU/β-CD-IC was determined to be 1:1. Computational modelling studies confirmed that 1:1 and 1:2 complex formation are desirable; 1:1 complex formation was chosen to have higher weight loading of QU. SEM images showed that PAA/QU/β-CD-IC-NF were bead-free and uniform. XRD indicated that PAA/QU/β-CD-IC-NF were amorphous in nature without the crystalline peaks of QU. Comparative results revealed that the release profile of QU from PAA/QU/β-CD-IC-NF was much slower but greater in total than from PAA/QU/β-CD-IC-film. Moreover, high antioxidant activity and photostability of QU was achieved in PAA/QU/β-CD-IC-NF.Item Open Access Tool allocation and machining conditions optimization for CNC machines(Elsevier, 1996) Aktürk, M. S.; Avcı, S.In the literature, there exist many variations of machining economics problem in terms of modelling approaches and solution methodologies. However most of the existing studies focus on the single machining operation which is seldom in practice. On the other hand, tool management approaches at the system level fail to relate the tooling issues to the machining conditions, and ignore the tool availability and tool wear restrictions. A new solution methodology is developed to determine the optimum machining conditions and tool allocation simultaneously to minimize the production cost of a multiple operation case where there can be alternative tools for each operation. As a result, we can both improve the solution by exploiting the interaction between these two decisions, and also prevent any infeasibility that might occur for the tool allocation problem due to tool contention among the operations for a limited number of tool types by considering the tool availability and tool life limitations.