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2000

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Articles 2371 - 2400 of 2640

Full-Text Articles in Physical Sciences and Mathematics

Ce-Qual-W2 Version 3: Hydrodynamic And Water Quality River Basin Modeling, Scott A. Wells Jan 2000

Ce-Qual-W2 Version 3: Hydrodynamic And Water Quality River Basin Modeling, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

CE-QUAL-W2 is a two-dimensional (longitudinal-vertical) water quality and hydrodynamic computer simulation model that was originally developed for deep, long, and narrow waterbodies. The current model, Version 2, has been used in over 200 river, reservoir/lake, and estuary applications throughout the U.S. and abroad. Version 2, though, cannot accommodate systems that have a significant sloping water surface since the vertical coordinate system is aligned with gravity and vertical accelerations are neglected. The governing equations for CE-QUAL-W2 were re-derived so that it could be applied to entire river basins including river-estuary, lake-river, and reservoir-river systems with channel slopes. This re-derivation is one …

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Modeling The Bull Run River-Reservoir System, Scott A. Wells Jan 2000

Modeling The Bull Run River-Reservoir System, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

The City of Portland, Water Bureau currently operates 2 Bull Run reservoirs, Reservoir #2 and Reservoir #1 as a water supply source in the Bull Run watershed shown in Figure 1 and Figure 2. The Water Bureau wants to operate their water supply system in order to meet both water supply objectives and fish habitat objectives downstream of the Bull Run reservoirs in Bull Run River. In addition, a third Bull Run reservoir has been proposed as an additional water supply source. This reservoir also may be used to meet water supply and fish habitat objectives in Bull Run River. …

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Variation Of Constitutive Model Formulation On Analytical Cake Filtration Models, Scott A. Wells Jan 2000

Variation Of Constitutive Model Formulation On Analytical Cake Filtration Models, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

Constitutive properties are required to model porosity, effective stress, porewater pressure, or permeability during cake filtration. By using an analytical cake filtration model based on Tiller (1975) with various constitutive property formulations, predictions of effective stress, permeability, and porosity distributions in a filter cake can be made. This analytical approach was only valid when spatially average values of porosity and pressure differential were constant over time. Several different constitutive property formulations were compared to data of effective stress and permeability as a function of porosity for kaolin clay in water. Also the spatial distribution of porosity in a filter cake …

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Optical Performance Of Grazing Incidence X-Ray / Euv Telescopes For Space Science Applications, Patrick Louis Thompson Jan 2000

Optical Performance Of Grazing Incidence X-Ray / Euv Telescopes For Space Science Applications, Patrick Louis Thompson

Retrospective Theses and Dissertations

The science and technology of X-rays has only been part of human achievement for the past 100 years, while the study of image formation in general has endured for as long as 1000 years. The ability to conceive, design, and fabricate X-ray imagers, moreover, has existed for only the past 70 years, and X-ray astronomical telescopes have been in use for a mere 35 years. Considering that aplanatic, normal incidence telescope designs required more than 400 years to perfect, it is most interesting to note that the development of ‘aplanatic’ grazing incidence telescopes has taken only about 40 years. In …

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Welcoming Address: "Mathematical Concepts In Politics", Erdal İnönü Jan 2000

Welcoming Address: "Mathematical Concepts In Politics", Erdal İnönü

Turkish Journal of Physics

No abstract provided.

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Generalized 2d Yang-Mills Theories: Large-N Limit And Phase Structure, Masoud Alimohammadi Jan 2000

Generalized 2d Yang-Mills Theories: Large-N Limit And Phase Structure, Masoud Alimohammadi

Turkish Journal of Physics

After review the 2D Yang--Mills theories (YM$_2$) and its large--$N$ behaviour, the Generalized 2D Yang--Mills theories (gYM$_2$) and their partition functions on a general two--dimensional Riemann surface are discussed.The large--$N$ behaviour of these models is studied in weak regime, and in strong regime, we restrict ourselves to $\phi^4$ gYM$_2$. We show that this model has a third order phase transition, similar to ordinary YM$_2$ theory.

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Analysis On The 2-Dim Quantum Poincare Group At Roots Of Unity, Haji Ahmedov Jan 2000

Analysis On The 2-Dim Quantum Poincare Group At Roots Of Unity, Haji Ahmedov

Turkish Journal of Physics

2--Dim quantum Poincar\'e Group $E_q(1,1)$ at roots of unity, its dual $U_q(e(1,1))$ and some of its homogeneous spaces are introduced. Invariant integrals on $E_q(1,1)$ and its invariant discrete subgroup $E(1,1\mid p)$ are constructed. $*$--Representations of the quantum algebra $U_q(e(1,1))$ constructed in the homogeneous space $SO(1,1\mid p)$ are integrated to the pseudo--unitary representations of $E_q(1,1)$ by means of the universal $T$--matrix. $U_q(e(1,1))$ is realized on the quantum plane $E_q^{(1,1)}$ and the eigenfunctions of the complete set of observables are obtained in the angular momentum and momentum basis. The matrix elements of the pseudo--unitary irreducible representations are given in terms of the …

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Quark And Lepton Masses From Fundamental Algebra With Exact Color Symmetry, Engi̇n Arik, Meti̇n Arik, Ufuk Kayserilioglu, M. Burcin Unlu Jan 2000

Quark And Lepton Masses From Fundamental Algebra With Exact Color Symmetry, Engi̇n Arik, Meti̇n Arik, Ufuk Kayserilioglu, M. Burcin Unlu

Turkish Journal of Physics

We propose a deformed algebra of creation and annihilation operators relating quark-lepton states. A diagonal mass operator with three parameters together with the three deformation parameters of the algebra gives a reasonable fit to observed quark-lepton masses.

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On Fermi - Bose Symmetry In Conformal Field Theory, A. Belavin Jan 2000

On Fermi - Bose Symmetry In Conformal Field Theory, A. Belavin

Turkish Journal of Physics

The minimal models of CFT possess a few algebraic structures. Besides the Virasoro Algebra which is an explicit symmetry of these models they have also Quantum Group structure and Fermi-Bose duality. We discuss the relationship between these things.

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Monopole Equations On R^8: The Energy Integral, Ayşe Hümeyra Bi̇lge, Teki̇n Dereli̇, Şahi̇n Koçak Jan 2000

Monopole Equations On R^8: The Energy Integral, Ayşe Hümeyra Bi̇lge, Teki̇n Dereli̇, Şahi̇n Koçak

Turkish Journal of Physics

We discuss the Seiberg-Witten theory in four dimensions and possible generalizations to eight dimensions. We propose an action which is minimized by a set of monopole equations, previously obtained as a generalization of Seiberg-Witten theory to eight manifolds with Spin(7) holonomy.

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Kerr Spinning Particle, A. Burinskii Jan 2000

Kerr Spinning Particle, A. Burinskii

Turkish Journal of Physics

We give a brief review of the problems connected with the model of spinning particle based on the Kerr geometry. We consider peculiarities of the Kerr rotating black hole solution in gravity, supergravity and low energy string theory. A non-trivial supergeneralization of the Kerr-Newman solution to broken N=2 supergravity is considered. \par The problem of source of the Kerr geometry is discussed, and we consider some arguments in favor of the supersymmetric Fermi-ball model for the Kerr source based on the Witten $U(1)\times U(\tilde 1)$ field model for superconducting strings.

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Global Results In Space Of Inter-Monomer Interactions For Hp Lattice Model, M. R. Ejtehadi̇, V. Shahrezaei̇, N. Hamedani̇ Jan 2000

Global Results In Space Of Inter-Monomer Interactions For Hp Lattice Model, M. R. Ejtehadi̇, V. Shahrezaei̇, N. Hamedani̇

Turkish Journal of Physics

Using the ground state candidates for Hydrophobic-Polar lattice model on a two dimensional square lattice, we exactly enumerate the native states of proteins with length up to 20 for a wide range of energy parameters. We find the reduced set of contact maps, ground state candidates, perfectly stable sequences and designability of configurations.

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The Statistics Of Energy States Of A Hookean Model For Proteins, Ayşe Erzan, Erkan Tüzel Jan 2000

The Statistics Of Energy States Of A Hookean Model For Proteins, Ayşe Erzan, Erkan Tüzel

Turkish Journal of Physics

A generic model of a random polypeptide chain, with discrete torsional degrees of freedom and Hookean springs connecting pairs of hydrophobic residues, reproduces the energy probability distribution of real proteins over a very large range of energies. We show that this system with harmonic interactions, under dissipative dynamics driven by random noise, leads to a distribution of energy states obeying a modified one-dimensional Ornstein-Uhlenbeck process with reflecting boundary conditions, and giving rise to distributions of the Wigner or inverse Gaussian form. A continuum approximation leads to a path integral formulation of the problem. PACS 5.65+b,5.70Ln,87.17.Aa

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Gauge Invariant Reduction And Integrability Of Sl(2 ,R)/ U(1) Wznw Theory, Chris Ford, George Jorjadze, Gerhard Weigt Jan 2000

Gauge Invariant Reduction And Integrability Of Sl(2 ,R)/ U(1) Wznw Theory, Chris Ford, George Jorjadze, Gerhard Weigt

Turkish Journal of Physics

The general solution of $SL(2,{\bf R})/U(1)$ WZNW theory is constructed by a gauge invariant reduction. This is done within both Lagrangian and Hamiltonian frameworks.

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A Detour In De Sitter Space While Calculating Vacuum Fluctuatins, M. Hortaçsu Jan 2000

A Detour In De Sitter Space While Calculating Vacuum Fluctuatins, M. Hortaçsu

Turkish Journal of Physics

{We study vacuum fluctuations of different gravitational waves by taking a detour in de Sitter space in the intermediate steps. We find finite contributions when the coupling constant is dimensionless, whereas null result persists in the cases with dimensional coupling constants. We also test our method for exactly solvable cases, and show that no spurious perturbative effects are introduced through our method.

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Multi-Species Asymmetric Exclusion Process In Ordered Sequential Update, M. Ebrahi̇m Fouladvand, Farhad Jafarpour Jan 2000

Multi-Species Asymmetric Exclusion Process In Ordered Sequential Update, M. Ebrahi̇m Fouladvand, Farhad Jafarpour

Turkish Journal of Physics

A multi-species generalization of the asymmetric simple exclusion process (ASEP) is studied in ordered sequential and sub-lattice parallel updating schemes. In this model, particles hop with their own specific probabilities to their rightmost empty site and fast particles overtake slow ones with a definite probability. Using Matrix Product Ansatz (MPA), we obtain the relevant algebra, and study the uncorrelated stationary state of the model both for an open system and on a ring. A complete comparison between the physical results in these updates and those of random sequential introduced in [20,21] is made.

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Product Integral Representations Of Wilson Lines And Wilson Loops And Non-Abelian Stokes Theorem, Robert L. Karp, Freydoon Mansouri, Jung S. Rno Jan 2000

Product Integral Representations Of Wilson Lines And Wilson Loops And Non-Abelian Stokes Theorem, Robert L. Karp, Freydoon Mansouri, Jung S. Rno

Turkish Journal of Physics

We make use of product integrals to provide an unambiguous mathematical representation of Wilson line and Wilson loop operators. Then, drawing upon various properties of product integrals, we discuss such properties of Wilson lines and Wilson loops as approximating them with partial sums, their convergence, and their behavior under gauge transformations. We also obtain a surface product integral representation for the Wilson loop operator. The result can be interpreted as the non-abelian version of Stokes theorem.

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On Integrable Systems Related To Semisimple Lie Groups, G. A. Keri̇mov Jan 2000

On Integrable Systems Related To Semisimple Lie Groups, G. A. Keri̇mov

Turkish Journal of Physics

Quantum scattering systems related to the noncompact semisimple Lie groups G in the sense that the Hamiltonian of the system can be written as a function of the Casimir operator of G are considered. The S-matrix for such systems are defined in terms of an interwining operator of underling symmetry group G.

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Nonabelian Cosmic Strings From So(3) Gauge Symmetry, Mehmet Koca Jan 2000

Nonabelian Cosmic Strings From So(3) Gauge Symmetry, Mehmet Koca

Turkish Journal of Physics

The nature of $SO(3)$ breaking into its closed subgroups and the emergence of nonabelian cosmic strings are discussed. Relevance to GUT breaking and thereby to cosmology is pointed out. Classification of cosmic strings are associated with the affine ADE Lie algebras.

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Cosmological Adiabatic Geometric Phase Of A Scalar Field In A Bianchi Spacetime, Ali̇ Mostafazadeh Jan 2000

Cosmological Adiabatic Geometric Phase Of A Scalar Field In A Bianchi Spacetime, Ali̇ Mostafazadeh

Turkish Journal of Physics

A two-component formulation of the Klein-Gordon equation is used to investigate the cyclic and noncyclic adiabatic geometric phases due to spatially homogeneous (Bianchi) cosmological models. It is shown that no adiabatic geometric phases arise for Bianchi type I models. For general Bianchi type IX models the problem of the adiabatic geometric phase is shown to be equivalent to the one for nuclear quadrupole interactions of a spin. For these models nontrivial non-Abelian adiabatic geometrical phases may occur in general.

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From Antibracket To Equivariant Characteristic Classes, Armen Nersessian Jan 2000

From Antibracket To Equivariant Characteristic Classes, Armen Nersessian

Turkish Journal of Physics

We equip the exterior algebra of Riemann manifold by the odd symplectic structure. Then, by its use we construct the equivariant even (pre)symplectic structure, whose Poincare - Cartan invariants of the second structure define the equivariant Euler classes of the surfaces.

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On The Duality Of Quantum Liouville Field Theory, L. O'Raifeartaigh, J. M. Pawlowski, V. V. Sreedhar Jan 2000

On The Duality Of Quantum Liouville Field Theory, L. O'Raifeartaigh, J. M. Pawlowski, V. V. Sreedhar

Turkish Journal of Physics

It has been found empirically that the Virasoro centre and 3-point functions of quantum Liouville field theory with potential $e^{2b\phi(x)}$ and external primary fields exp($\alpha\phi(x)$) are invariant with respect to the duality transformations $\hbar \alpha\rightarrow q-\alpha$ where $q=b^{-1}+b$. The steps leading to this result (via the Virasoro algebra and 3-point functions) are reviewed in the path-integral formalism. The duality stems from the fact that the quantum relationship between the $\alpha$ and the conformal weights $\Delta_\alpha$ is two-to-one. As a result the quantum Liouville potential may actually contain two exponentials (with related parameters). It is shown that in the two-exponential theory …

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Chaos In Closed Isotropic Cosmological Models With Steep Scalar Field Potential, A. V. Toporensky Jan 2000

Chaos In Closed Isotropic Cosmological Models With Steep Scalar Field Potential, A. V. Toporensky

Turkish Journal of Physics

The dynamics of closed scalar field FRW cosmological models is studied for several types of exponentially and more than exponentially steep potentials. The parameters of scalar field potentials which allow a chaotic behaviour are found from numerical investigations. It is argued that analytical studies of equation of motion at the Euclidean boundary can provide an important information about the properties of chaotic dynamics. Several types of transition from chaotic to regular dynamics are described.

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Coherent States For The Hydrogen Atom, Nuri̇ Ünal Jan 2000

Coherent States For The Hydrogen Atom, Nuri̇ Ünal

Turkish Journal of Physics

We obtained the coherent states for the hydrogen atom by transforming the problem onto the four oscillators in the parametric time at the classical level and quantizing these oscillators. We showed that for the coherent states the mean values of the physical position of the electron satisfy the Keplerian ellipsis and the dispersions of them oscillate in the parametric time.

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Parameterized Absolute Parallelism: A Geometry For Physical Applications, Mamdouh Ishaac Wanas Jan 2000

Parameterized Absolute Parallelism: A Geometry For Physical Applications, Mamdouh Ishaac Wanas

Turkish Journal of Physics

Absolute parallelism (AP) geometry is frequently used for physical applications. Although it is wider than the Riemannian geometry, it has two main defects. The first is that its path equation does not represent physical trajectories of any test particle. The second is the identical vanishing of its curvature tensor. The present work shows that parameterizing this geometry would solve the two problems. Furthermore, the resulting parameterized (AP)-structure is more general than both the conventional (AP)-structure and the Riemannian structure. Also, it is shown that it can be reduced to one or the other, of these two geometric structures, in some …

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Time Evolution Of Fast Particles During Decay Of Hadronic Systems, Mohamed Tarek Hussein, Nabila Mohamed Hassan, Nagla El-Harby Jan 2000

Time Evolution Of Fast Particles During Decay Of Hadronic Systems, Mohamed Tarek Hussein, Nabila Mohamed Hassan, Nagla El-Harby

Turkish Journal of Physics

A phenomenological model is presented based on the formation of a nuclear thermodynamic system during the collision of intermediate and high energy heavy ions. The formulation and the dynamic picture are determined by solving the Vlasov equation. The solution is dressed in the form of a power series the first term of which being the equilibrium distribution in phase space. The rest, are time dependent perturbation terms due to the multiple strong interactions inside the system. The temperature gradient and the derivatives of the phase function are calculated. The time dependence of the angular emission of the produced particles is …

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Positron Annihilation And Xrd Studies On Deformed Al-Alloys With Low Concentration Of Mg, Emad A. Badawi, M. A. Abdel-Rahman, S. A. Mahmoud, A. A. Ramadan Jan 2000

Positron Annihilation And Xrd Studies On Deformed Al-Alloys With Low Concentration Of Mg, Emad A. Badawi, M. A. Abdel-Rahman, S. A. Mahmoud, A. A. Ramadan

Turkish Journal of Physics

Positron behaviour at grain boundaries is characterized by their bulk diffusibility D, their bulk free lifetime $\tau_f$ and their trapped lifetime $\tau_t$ ($\tau_t > \tau_f).$ Al-Mgx samples (x = 0-1.4 at \%) have been homogenized at 573 K for 12 hours. The mean lifetime, as (indirectly) measured at various concentrations, show a good fitting with Sigmodel giving $\tau_t$ = 180.664 ps and $\tau_{f}$ = 163.9 ps. The mean lifetime was found to vary exponentially with the degree of deformation. The XRD study showed that preferred orientation occurred at degrees of deformation $>$ 32 \%, whereas the peak intensity then increases …

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A Glancing Incidence Exafs Study Of Evaporated Silver Films On Glass, Ahmet Bulut, Bünyami̇n Karabulut, Engi̇n Başaran, James Robinson Jan 2000

A Glancing Incidence Exafs Study Of Evaporated Silver Films On Glass, Ahmet Bulut, Bünyami̇n Karabulut, Engi̇n Başaran, James Robinson

Turkish Journal of Physics

A glancing incidence EXAFS experiment has been carried out with evaporated silver films on glass substrates. Prior to EXAFS data collection, a reflectivity curve was performed from which the critical angle for total external reflection of x-rays from surface were determined. The analysed EXAFS data revealed that there is a reduction in the coordination number and an increase in Debye-Waller factor compared to bulk values. These changes were explained in terms of grain size effect and the surface effects of the silver film.

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Internal Photoemission Spectroscopy For A Ptsi/P-Si Schottky Junction, Bülent Aslan, Raşi̇t Turan Jan 2000

Internal Photoemission Spectroscopy For A Ptsi/P-Si Schottky Junction, Bülent Aslan, Raşi̇t Turan

Turkish Journal of Physics

Properties of internal photoemission in a PtSi-Si Schottky junction have been studied. The traditional Fowler plot of a detector's photoyield is found to be nonlinear for values close to the barrier height of the junction. It is shown that the model that takes all scattering mechanisms into account provides a successful description for the experimental results. It is also shown that the photoemission spectrum is independent of temperature in agreement with this model. The properties of detector's ambient influence the photoemission spectrum for wavelength of 3 $\mu$m or less. A strong loss in the detector's response is observed at around …

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Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak Jan 2000

Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak

Turkish Journal of Physics

The second order contribution for the relativistic scattering of massless spin-$\frac{1}{2}$ particles from an infinitely long solenoid, in the context of covariant perturbation theory, is calculated and shown to vanish. Thus, Born approximation is consistent for this case as well.

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