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Yayın Contributions of higher order terms to nonlinear waves in fluid-filled elastic tubes: strongly dispersive case(Pergamon-Elsevier Science, 2003-07) Demiray, HilmiIn the present work, employing the nonlinear equations of an incompressible, isotropic and elastic thin tube and the approximate equations of an incompressible inviscid fluid, and then utilizing the modified reductive perturbation technique presented by us [15] the amplitude modulation of weakly nonlinear waves is examined. It is shown that the first order term in the perturbation expansion is governed by a nonlinear Schrodinger equation and the second order term is governed by the linearized Schrodinger equation with a nonhomogeneous term. In the longwave limit a travelling wave type of solution to these equations are also given.Yayın On the extraction of the channel allocation information in spectrum pooling systems(IEEE, 2007-04) Öner, Mustafa Mengüç; Jondral, Friedrich K.The spectrum pooling strategy allows a license owner to share a part of his licensed spectrum with a secondary wireless system (the rental system, RS) during its idle times. The coexistence of two mobile systems on the same frequency band poses many new challenges, one of which is the reliable extraction of the channel allocation information (CAI), i.e. the channel occupation of the licensed system (LS). This paper presents a strategy for the extraction of the CAI based on exploiting the distinct cyclostationary characteristics of the LS and RS signals and demonstrates, via simulations, its application on a specific spectrum pooling scenario, where the LS is a GSM network and the RS is an OFDM based WLAN system.Yayın Equilibrium and stability analysis of delayed neural networks under parameter uncertainties(Elsevier Science Inc, 2012-02-15) Faydasıçok, Özlem; Arik, SabriThis paper proposes new results for the existence, uniqueness and global asymptotic stability of the equilibrium point for neural networks with multiple time delays under parameter uncertainties. By using Lyapunov stability theorem and applying homeomorphism mapping theorem, new delay-independent stability criteria are obtained. The obtained results are in terms of network parameters of the neural system only and therefore they can be easily checked. We also present some illustrative numerical examples to demonstrate that our result are new and improve corresponding results derived in the previous literature.Yayın The economic lot-sizing problem with perishable items and consumption order preference(Elsevier Science BV, 2015-08-01) Önal, Mehmet; Romeijn, H. Edwin; Sapra, Amar; Van den Heuvel, WilcoWe consider the economic lot-sizing problem with perishable items (ELS-PI), where each item has a deterministic expiration date. Although all items in stock are equivalent regardless of procurement or expiration date, we allow for an allocation mechanism that defines an order in which the items are allocated to the consumers. In particular, we consider the following allocation mechanisms: First Expiration, First Out (FEFO), Last Expiration, First Out (LEFO), First In, First Out (FIFO) and Last In, First Out (LIFO). We show that the ELS-PI can be solved in polynomial time under all four allocation mechanisms in case of no procurement capacities. This result still holds in case of time-invariant procurement capacities under the FIFO and LEFO allocation mechanisms, but the problem becomes NP-hard under the FEFO and LIFO allocation mechanisms.Yayın Interactions of nonlinear acoustic waves in a fluid-filled elastic tube(Pergamon-Elsevier Science, 2001-03) Akgün, Güler; Demiray, HilmiIn the present work, the nonlinear interactions of two acoustical waves propagating in a fluid-filled elastic tube with different wave numbers, frequencies and group velocities are examined. Employing the multiple-scale expansion method, expanding the field quantities into asymptotic series of the smallness parameter and solving the resulting differential equations of various orders of the same parameter, we obtained two coupled nonlinear Schrodinger equations. The nonlinear plane wave solutions to these equations are also given for some special cases.Yayın Vapor-induced film formation from low-T-g particles for different solvent compositions(Elsevier Inc, 2006-05-15) Arda, Ertan; Kara, Selim; Saraç, Ayfer; Pekcan, Mehmet ÖnderThe photon transmission method was used to study latex film formation from poly(vinyl acetate) (PVAc) particles induced by two different solvents. Films with the same latex content were prepared from PVAc particles and exposed to vapor of ethanol-water and acetone-water mixtures in various compositions. Transmitted photon intensities, I-tr, from these films increased with increasing vapor exposure time. The increase in I-tr is attributed to the increase in crossing density at the polymer-polymer junction. The Prager-Tirrell model was employed to obtain the back-and-forth frequency, v, of the reptating polymer chain during film formation induced by solvent vapor. It was observed that the produced v values increase as the solvent content is increased for both solvents. Abilities of both solvents to form films were interpreted with the solubility parameters of the solvents and the PVAc.Yayın Effects of childhood trauma and clinical features on determining quality of life in patients with bipolar I disorder(Elsevier Science BV, 2014-06-20) Erten, Evrim; Funda Uney, Aslı; Saatçioğlu, İbrahim Ömer; Özdemir, Armağan; Fıstıkçı, Nurhan; Çakmak, DuranBackground: We explored how childhood trauma (CHT) affects the clinical expression of disorder and quality of life in patients with bipolar I (BP I) disorder.Methods: Euthymic patients (n=116) who subsequently received a diagnosis of BP-I disorder were consecutively included and were interviewed using the following sociodemographic and clinical data forms; Young Mania Rating Scale (YMRS), Hamilton Depression Rating Scale (HDRS), Childhood Abuse and Neglect Questionnaire (CANQ) and the 36 item Medical Outcome Study Short Form Health Survey (SF 36) The quality of life of BP-I patients with and without a history of CHT were examined.Results: The percentage of trauma was 61.2%. Patients who had CHT had higher frequencies of depressive episodes (t = -2.38, p=0.019), total episodes (t = -2.25, p=0.026), attempted suicide more often (chi(2)=18.12, p=0.003) and had lower scores on the pain subscale of Lhe SF 36 (z=-2.817, p=0.005). In patients with mixed or rapid-cycling episodes, SF-36 subscale scores except general health and pain were Found to be lower.Limitations: Our sample may fail to reflect the general BD population; the patients were included consecutively and consisted of a majority of female patients.Conclusions: CHT plays an important role in the clinical expression of BP-I disorder and having mixed/rapid-cycling episodes negatively affects both physical and mental components, as measured by the SF-36. While both males and females reported experiencing sexual abuse, female BP-I patients complained about pain more often. It is suggested that treatment of BP-1 patients with a history of CHT should differ from that provided for patients with no CHT history.Yayın Reversible film formation from PS doped PNIPAM particles in various compositions(John Wiley & Sons Inc, 2008-02) Uğur, Şaziye; Yargı, Önder; Pekcan, Mehmet ÖnderFilm formation from polystyrene (PS) doped poly(N-isopropylacrylamide) (PNIPAM) particles was studied using photon transmission technique. The transmitted light intensity, Itr, was monitored during film formation process. Films were prepared by mixing PS and PNIPAM particles in various compositions ranging from 5 to 50 %. Samples were separately heated and cooled in constant rate at temperatures ranging from 10 to 100 C. The increase and decrease in Itr during heating-cooling cycles were explained by void closure and void reconstruction processes. The corresponding activation energies were measured during the reversible film formation process. Percolation model was used to interpret the distribution of PS particles in PNIPAM lattice.Yayın Topography of inland deltas: Observations, modeling, and experiments(Amer Geophysical Union, 2010-04-28) Seybold, Hansjörg J.; Molnar, Peter; Akça, Mehmet Devrim; Doumi, M.; Tavares, M. Cavalcanti; Shinbrot, Troy; Andrade, Jose Soares; Kinzelbach, Wolfgang; Herrmann, Hans JürgenThe topography of inland deltas is influenced by the water-sediment balance in distributary channels and local evaporation and seepage rates. In this letter a reduced complexity model is applied to simulate inland delta formation, and results are compared with the Okavango Delta, Botswana and with a laboratory experiment. We show that water loss in inland deltas produces fundamentally different dynamics of water and sediment transport than coastal deltas, especially deposition associated with expansion-contraction dynamics at the channel head. These dynamics lead to a systematic decrease in the mean topographic slope of the inland delta with distance from the apex following a power law with exponent alpha = -0.69 +/- 0.02 where the data for both simulation and experiment can be collapsed onto a single curve. In coastal deltas, on the contrary, the slope increases toward the end of the deposition zone.Yayın Harmonic function for which the second dilatation is ?-spiral(Springer International Publishing AG, 2012) Aydoğan, Seher Melike; Duman, Emel Yavuz; Polatoğlu, Yaşar; Kahramaner, YaseminLet f = h + (g) over bar be a harmonic function in the unit disc . We will give some properties of f under the condition the second dilatation is alpha-spiral.
