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Item Uzayda yer tutan magnetik yükler ve bir hadron modeli(Thesis (Assoc. Prof.) - Bogazici University. Institute of Sciences and Engineering, 1977., 1977.) Beker, Haluk.Item Görülen ışığa duyarlı, ince filmle yapılmış bir optoelektronik aygıt(Thesis (Assoc. Prof.) - Bogazici University. Institute of Sciences and Engineering, 1978., 1978.) Iskarlatos, Yani.Item Bir E6 ayar alan teorisi modeli(Thesis (Assoc. Prof.) - Bogazici University. Institute of Sciences and Engineering, 1978., 1978.) Serdaroğlu, Meral.Item Kara deliklerin hiç süpersaçı yoktur(Thesis (Assoc. Prof.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1980., 1980.) Güven, Rahmi.Item 1,27-2,50 GeV/c momentumlu pozitif pionların protonlarla etkileşmeleri(Thesis (Assoc. Prof.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Arık, Engin.Item Weinberg-Salam model and e+ e- -> m+ m- process(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1981., 1981.) Kalaycı, Jan.; Hortaçsu, Mahmut.Item Geometrical approaches to soliton equations(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineerig, 1981., 1981.) Muğan, Uğurhan.; Güven, Rahmi.Item Grand unified models and neutrino oscillations(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Neyzi, Fahrünisa.; Arık, Metin.Item Cononical structure and integrability of new-dimensional field theories(Thesis (Ph.D.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1984., 1984.) Neyzi, Fahrünisa.; Arık, Metin.Item On the classical solutions of field theoretical models(Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1984., 1984.) Kalaycı, Jan.; Hortaçsu, Mahmut.Item Path integrals in quantum theory and some applications to homogeneous spaces(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1985., 1985.) Yenice, Kamil Mehmet.; Arık, Metin.In this work we consider the path integrals in quantum theory and some of their applications to homogeneous spaces from the semiclassical point of view. We begin with the basic principles underlying the Feynman path integral formulation of quantum mechanics and show the do;nain where the method is useful and powerful. We present a method for calculating the path integrals for quadratic Lagrangians and apply it to the example of harmonic oscillator. Semiclassical propagator given by the Van Vleck-Pauli formula is also discussed. We next handle the Hamiltonian derivation of path integral. The starting-point for this derivation is the usual operator formalism of quantum mechanics. Later on we consider path integrals on homogeneous spaces concentrating on the motion on group manifolds. It turns out that for the free motion on the group manifold the semiclassical approximation the exact solution. We thus study the path integrals for U(l) and SU(2) groups. In these cases the Propagator is calculated directly by two methods : the sum over classical paths and the stationary state expansion, which are shown explicitly to be equivalent. We finally give some remarks for motion on the hyperspheres S2n +1 and S2n. Deriving a recursion relation for the propagator of S2n +1 we claim that there is the possibility of getting the exact solution from some kind of semiclassical propagator for S2n +1.Item The design and construction of a tea molecular nitrogen laser system(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1988., 1988.) Kurt, Adnan.; Wetherilt, James A.In this study the design and construction of a molecular nitrogen laser intended as a pump source for a dye laser system is presented. This . laser radiation at a wavelength of 337.1 nanometers and uses Blumlein switching to achieve fast (N a few nanosecond width) and high peaK power (N a few hundred Kilowatts) pulses. It operates using atmospheric pressure nitrogen with a cavity length of ten centimeters. The incorporation of this laser into a wavelength tunable, pumped dye laser system is outlined. Methods for studying fast optical pulses are given. ivItem Gauge theories based on quantum groups, representations of the braid group(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1993., 1993.) Yıldız, Ali.; Arık, Metin.Possible formulations of gauge field models where the gauge group is a quantum group are discussed. The exponential map from the generators of the Lie algebra analog of the quantum group SUq(2) to the quantum group SUq(2) itself is presented. The q-deformed Yang-Mills theory is introduced via the definition of the q-trace and the q-deformed YangMills lagrangian which is invariant under the quantum group gauge transformations. The gauge field takes values in the quantum universal enveloping algebra of SUq(2). As a result of this construction a Weinberg type mixing angle which depends on the quantum group deformation parameter q is obtained. The representations of the n-braid group where generators are given essentially by 2 x 2 matrices whose elements belong to a noncommutative algebra are presented. The Burau representation arises as a special (commuting) case of this algebra. A closely related algebra to the braid algebra is introduced and it is shown that the generalized oscillator system given by this algebra generates a hydrogen-like spectrum.Item Unitary group and quantum group invariant q-oscillators and fibonaccization(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1994., 1994.) Ünel, N. Gökhan.; Arık, Metin.After a review of different types of q-oscillators and the relationship between their creation/ annihilation operators, the derivation of the q generalized version of the LeviCivita tensor (E) is given. The properties of the quantum group SLq(n) are obtained through the invariance properties of the new q-epsilon tensor. The relations between the inner products of n-particle states of the various q-oscillators are also investigated. Finally, a two parameter generalization of the Coon-Baker-Yu q-oscillator (which we call Fibonaccization) is presented.Item Determination of density of states of n-type hydrogenated amorphous silicon by phase shift analysis of modulated photocurrent method(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1995., 1995.) Kocabıyık, Ferhat.; Aktaş, Gülen, 1951- .Determination of density of states of hydrogenated amorphous siliconby phase shift analysis of modulated photocurrent.Determination of the energetic distribution of localized statesdue to random network and structural defects within the mobility gap of amorphous semi conductorsis of great importance for understanding the transport properties of these materials. Since there is no structural order,the band states can be only determined experimentally.In this thesis, the density of states (DOS) distribution in the energy gapof Hydrogenated n-type amorphous silicon is determined. For this purpose a The Phase shift analysis of modulated photocurrent (PSAMP) method is studied. The validity of the PSAMP theorem for the doped a-H:Si is discussed. The theorem is verified for this type of semiconductors and the distribution of the states is determined for a range of 400 meV.Item Muon track reconstruction from cathode strip readout of streamer tube planes in chorus muon spectrometer(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1996., 1996.) Perdahçı, Nazım Ziya.; Arık, Engin.We have studied several methods to achieve the best spatial resolution and the highest track reconstruction efficiency using the limited streamer tube planes with external pickup strips orthogonal to signal wires and the analog readout of the CHORUS Muon Spectrometer. The analysis has been performed with real data of 100 GeV beam muons at CERN Labarotary in Geneva. Using a combined algorithm of common bias level subtraction and an empirical function to determine the center of the induced charge distribution on the 18 mm wide strips, we have obtained a spatial resolution of about 3 mmItem Signs and magnitudes of Lyapunov exponents in continuous time dynamical systems(Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Sciences and Engineering, 1997., 1997.) Birol, İnanç.; Hacinliyan, Avadis.Methods for algebraically determining the signs and the magnitudes of Lyapunov exponents of a given dynamical system are studied.A number of Hamiltonian and dissipative systems are investigated.The existence of zero Lyapunov exponents for the Toda and Henon-Heiles systems are shown using the curvature of their potentials functions.For the Rossler system,the root bracketing criterion is used to show the existence of a zero Lyapunov exponent.The approximate Lyapunov spectra of Lorenz and Rossler systems are computed using the approximation schemes introduced.Item Stereographic coordinates for unitary quantum groups(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1998., 1998.) Arıkan, Ali Serdar.; Arık, Metin.In this thesis, unitary matrix representation of quantum group SUq(2) is studied in terms of stereographic coordinates z, z* and its central unitary phase u. It is observed that this parametrization of SUq(2) can be regarded as q-1-oscillator representation of SUq(2) where q-1>1. The fractional linear transformation of z and z* which gives the action of SUq(2) on the quantum sphere SUq(2)/U(1) is studied. Then we extend this action to SUq(2) and derive the transformation law of u. In the final part of this work, transformation laws for dz and are also studied.Item Integrability of non-linear differential equations; lax formulation and bi-Hamiltonian structures(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Sciences and Engineering, 1998., 1998.) Güntürk, Kamil Serkan.; Oğuz, Ömer.The integrability of non-linear differential equations are studied on the basis of Lax and bi-Hamiltonian formulations. The relations between the Lax formalism and bi-Hamiltonian structures are analysed and illustrated with well known examples such as the KdV system. Various methods resulting from this analysis are then applied to multicomponent KdV equations.Item AE AQR :|a DQ her type cataclysmic variable binary system(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1998., 1998.) Erkut, M. Hakan.; Ercan, E. Nihal.AE Aquarii, a DQ Her type Cataclysmic Variable X-ray binary system, is observed with rosat, PSPC in the energy range 0.1-2.4 keV with a total of 5.74 hr period. As a result of spectral and timing analyses of the ROSAT X-ray data of AE Aquarii, it is found that both a very low mass accretion rate of 8.59 x 10-13M yr-1 estimated from the X-ray luminosity and a QPO like structure obderved in the X-ray average power spectrum support the magnetic propeller scenario in which the gas blobs of the inhomogeneous accretion stream from the secondary star to the white dwarf are radiated thermally near the white dwarf surface because of the shock heating of the gas blobs at supersonic speeds in the high accretion state of AE Aquarii. On the other hand, the accreted gas particles are radiated magnetically in ~ 10 Gauss of magnetospere far away from the white dwarf surface during the low accretion states.