Browsing by Subject "Systems"

Now showing 1 - 10 of 10

Open Access
Activity analysis for assistive systems
(2014) İşcen, Ahmet
Although understanding and analyzing human actions is a popular research topic in computer vision, most of the research has focused on recognizing ”ordinary” actions, such as walking and jumping. Extending these methods for more specific domains, such as assistive technologies, is not a trivial task. In most cases, these applications contain more fine-grained activities with low inter-class variance and high intra-class variance. In this thesis, we propose to use motion information from snippets, or small video intervals, in order to recognize actions from daily activities. Proposed method encodes the motion by considering the motion statistics, such as the variance and the length of trajectories. It also encodes the position information by using a spatial grid. We show that such approach is especially helpful for the domain of medical device usage, which contains actions with fast movements Another contribution that we propose is to model the sequential information of actions by the order in which they occur. This is especially useful for fine-grained activities, such as cooking activities, where the visual information may not be enough to distinguish between different actions. As for the visual perspective of the problem, we propose to combine multiple visual descriptors by weighing their confidence values. Our experiments show that, temporal sequence model and the fusion of multiple descriptors significantly improve the performance when used together.
Open Access
A bayesian network analysis of ethical behavior
(SAGE Publications Inc., 2016) Ekici, A.; Ekici, S. O.
Using one of the major domains of macromarketing – ethics – this paper aims to introduce the Bayesian network (BN) method and demonstrate its added value for macro-level decision makers. Bayesian networks are particularly important for macromarketers because they allow researchers to analyze a domain from a system perspective. The BN approach is considered one of the most powerful tools for observing system changes. The method can also deal with multiple variables at once, which can lead to efficient scenario analyses, critical for understanding how a system functions. As such, BNs offer a powerful tool for macromarketers who deal with systems, interactions, and higher levels of aggregation. We believe that the adoption of this methodology by macromarketing researchers is likely to contribute to the discipline by advancing the understanding of how certain systemic/network relationships and various domains of macromarketing work.
Open Access
Bistable behavior of a two-mode Bose-Einstein condensate in an optical cavity
(IOP Institute of Physics Publishing, 2013-01-11) Safaei, S.; Mustecaplioglu, Ö. E.; Tanatar, Bilal
We consider a two-component Bose-Einstein condensate in a one-dimensional optical cavity. Specifically, the condensate atoms are taken to be in two degenerate modes due to their internal hyperfine spin degrees of freedom and they are coupled to the cavity field and an external transverse laser field in a Raman scheme. A parallel laser also excites the cavity mode. When the pump laser is far detuned from its resonance atomic transition frequency, an effective nonlinear optical model of the cavity-condensate system is developed under the discrete mode approximation (DMA), while matter-field coupling has been considered beyond the rotating wave approximation. By analytical and numerical solutions of the nonlinear dynamical equations, we examine the mean cavity field and population difference (magnetization) of the condensate modes. The stationary solutions of both the mean cavity field and normalized magnetization demonstrate bistable behavior under certain conditions for the laser pump intensity and matter-field coupling strength.
Open Access
Energy transfer rate in Coulomb coupled quantum wires
(American Institute of Physics, 1997) Tanatar, Bilal
We study the energy transfer rate for electrons in two parallel quantum wires due to interwire Coulomb interactions. The energy transfer rate between the wires (similar to the Coulomb drag effect in which momentum transfer rate is measured) is calculated as a function of temperature for several wire separation distances. We employ the full wave vector and frequency dependent random-phase approximation at finite temperature to describe the effective interwire Coulomb interaction. We find that the energy transfer rate at intermediate temperatures (i.e., T similar to 0.3E(F)) is dominated by the collective modes (plasmons) of ale system. Nonlinear effects on the energy transfer rate is also explored. (C) 1997 American Institute of Physics.
Open Access
Hydrodynamic type of integrable equations on a segment and a half line
(American Institute of Physics, 2008) Gurses, M.; Habibullin, I.; Zheltukhin, K.
The concept of integrable boundary conditions is applied to hydrodynamic type systems. Examples of such boundary conditions for dispersionless Toda systems are obtained. The close relation of integrable boundary conditions with integrable reductions in multifield systems is observed. The problem of consistency of boundary conditions with the Hamiltonian formulation is discussed. Examples of Hamiltonian integrable hydrodynamic type systems on a segment and a semiline are presented. © 2008 American Institute of Physics.
Open Access
A new mapping heuristic based on mean field annealing
(Academic Press, 1992) Bultan, T.; Aykanat, Cevdet
A new mapping heuristic is developed, based on the recently proposed Mean Field Annealing (MFA) algorithm. An e cient implementation scheme, which decreases the complexity of the proposed algorithm by asymptotical factors, is also given. Performance of the proposed MFA algorithm is evaluated in comparison with two wellknown heuristics; Simulated Annealing and Kernighan-Lin. Results of the experiments indicate that MFA can be used as an alternative heuristic for solving the mapping problem. Inherent parallelism of MFA is exploited by designing an e cient parallel algorithm for the proposed MFA heuristic.
Open Access
Onion-Like (CdSe)ZnS/CdSe/ZnS quantum-dot-quantum-well heteronanocrystals for investigation of multi-color emission
(Optical Society of America, 2008) Nizamoglu, S.; Demir, Hilmi Volkan
We investigate multi-color spontaneous emission from quantum-dot-quantum-well heteronanocrystals made of onion-like (CdSe) ZnS/CdSe/ZnS ( core) shell/shell/shell structures, with our theoretical results explaining experimental measurements for the first time. In such multi-layered heteronanocrystals, we discover that the carrier localization is tuned from type-1-like to type-2-like localization by controlling CdSe and ZnS shell thicknesses, and that 3-monolayer ZnS barriers are not necessarily sufficient for carrier localization, unlike in conventional ( CdSe) ZnS ( core) shell structures. We demonstrate that exciton localization in distinct layers of ( CdSe) ZnS/CdSe/ZnS heteronanocrystals with high transition probability ( for n=1 states in CdSe core and n=2 states in CdSe shell) is key to their multi-color emission. (c) 2008 Optical Society of America.
Open Access
Operational research: methods and applications
(Taylor and Francis Ltd., 2023-12-27) Petropoulos, F.; Laporte, G.; Aktas, E.; Alumur, S.; Archetti, C.; Ayhan, H.; Battarra, M.; Bennell, J.; Bourjolly, J.; Boylan, J. E.; Breton, M.; Canca, D.; Charlin, L.; Chen, B.; Cicek, C.; Cox, L.; Currie, C. S.M.; Demeulemeester, E.; Ding, L.; Disney, S. M.; Ehrgott, M.; Eppler, M. J.; Erdoğan, G.; Fortz, B.; Franco, L. A.; Frische, J.; Greco, S.; Gregory, A. J.; Hämäläinen, R. P.; Herroelen, W.; Hewitt, M.; Holmström, J.; Hooker, J. N.; Işık, T.; Johnes, J.; Kara, B. Y.; Karsu, Özlem; Kent, K.; Köhler, C.; Kunc, M.; Kuo, Y.; Letchford, A. N.; Leung, J.; Li, D.; Li, H.; Lienert, J.; Ljubić, I.; Lodi, A.; Lozano, S.; Lurkin, V.; Martello, S.; McHale, I. G.; Midgley, G.; Morecroft, J. D.W.; Mutha, A.; Oğuz, C.; Petrovic, S.; Pferschy, U.; Psaraftis, H. N.; Rose, S.
Throughout its history, Operational Research has evolved to include methods, models and algorithms that have been applied to a wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first summarises the up-to-date knowledge and provides an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion and used as a point of reference by a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes.
Open Access
Optical implementations of two-dimensional fractional Fourier transforms and linear canonical transforms with arbitrary parameters
(Optical Society of America, 1998-04-10) Sahin, A.; Özaktaş, Haldun M.; Mendlovic, D.
We provide a general treatment of optical two-dimensional fractional Fourier transforming systems. We not only allow the fractional Fourier transform orders to be specified independently for the two dimensions but also allow the input and output scale parameters and the residual spherical phase factors to be controlled. We further discuss systems that do not allow all these parameters to be controlled at the same time but are simpler and employ a fewer number of lenses. The variety of systems discussed and the design equations provided should be useful in practical applications for which an optical fractional Fourier transforming stage is to be employed.
Open Access
Superimposed event detection by particle filters
(The Institution of Engineering and Technology, 2011) Urfalioglu, O.; Kuruoglu, E. E.; Çetin, A. Enis
In this study, the authors consider online detection and separation of superimposed events by applying particle filtering. They observe only a single-channel superimposed signal, which consists of a background signal and one or more event signals in the discrete-time domain. It is assumed that the signals are statistically independent and can be described by random processes with known parametric models. The activation and deactivation times of event signals are assumed to be unknown. This problem can be described as a jump Markov system (JMS) in which all signals are estimated simultaneously. In a JMS, states contain additional parameters to identify models. However, for superimposed event detection, the authors show that the underlying JMS-based particle-filtering method can be reduced to a standard Markov chain method without additional parameters. Numerical experiments using real-world sound processing data demonstrate the effectiveness of their approach.