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2017

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Articles 10831 - 10860 of 11102

Full-Text Articles in Physical Sciences and Mathematics

The Milne Problem Using The P$_{N}$ Method For A Nonabsorbing Medium With Linearly Anisotropic Scattering, Mustafa Çeti̇n Güleçyüz, Ahmet Ersoy Jan 2017

The Milne Problem Using The P$_{N}$ Method For A Nonabsorbing Medium With Linearly Anisotropic Scattering, Mustafa Çeti̇n Güleçyüz, Ahmet Ersoy

Turkish Journal of Physics

The Milne problem, known as one of the classical problems of radiative transfer and neutron transport theory, is solved using the P$_{N}$ method for a nonabsorbing medium (c = 1) with a linearly anisotropic scattering kernel. Specular and diffuse reflection boundary conditions are taken into account. The numerical results are listed for different selected parameters. Some results are also compared with the literature.

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A Theoretical Study Of Radio Wave Attenuation Through A Polycrystalline Silicon Solar Cell, Adama Ouedraogo, Vinci De Dieu Bokoyo Barandja, Issa Zerbo, Martial Zoungrana, Emmanuel Wendsongre Ramde, Dieudonne Joseph Bathiebo Jan 2017

A Theoretical Study Of Radio Wave Attenuation Through A Polycrystalline Silicon Solar Cell, Adama Ouedraogo, Vinci De Dieu Bokoyo Barandja, Issa Zerbo, Martial Zoungrana, Emmanuel Wendsongre Ramde, Dieudonne Joseph Bathiebo

Turkish Journal of Physics

One-dimensional study of both electronic and electrical parameters of a silicon solar cell in the presence or not of an electric field, a magnetic field, or an electromagnetic field does not take into account the grain size and the grain boundary recombination velocity. A three-dimensional study, on the contrary, takes those factors into account. However, the three-dimensional study poses the problem of the attenuation of the wave in the grain of the polycrystalline solar cell as well as the issue of finding the expressions of its components. This study aimed to solve these issues by considering radio waves, which are …

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Remarks On The Treatments Of Nonsolvable Potentials, Bülent Gönül, Yücel Cançeli̇k Jan 2017

Remarks On The Treatments Of Nonsolvable Potentials, Bülent Gönül, Yücel Cançeli̇k

Turkish Journal of Physics

A recently introduced scheme is extended to propose an algebraic nonperturbative approach for the analytical treatment of Schrödinger equations with nonsolvable potentials involving an exactly solvable potential form together with an additional potential term. As an illustration the procedure is successfully applied to the Cornell potential by means of very simple algebraic manipulations. However, instead of providing numerical eigenvalues for the only consideration of the small strength of the related linear potential as in the previous reports, the present model puts forward a clean route to interpret related experimental or precise numerical results involving a wide range of the linear …

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Enhanced Electro-Optic Modulation Of Linbo$_{3}$-Based Photonic Crystal Cavities With Dual Mode And Polarization Operation, Fulya Bağci, Gökhan Kurt, Bariş Akaoğlu, Ekmel Özbay Jan 2017

Enhanced Electro-Optic Modulation Of Linbo$_{3}$-Based Photonic Crystal Cavities With Dual Mode And Polarization Operation, Fulya Bağci, Gökhan Kurt, Bariş Akaoğlu, Ekmel Özbay

Turkish Journal of Physics

A high output transmission and high quality factor, compact LiNbO$_{3}$-based Fabry-Perot-type photonic crystal cavity is reported that can be used in electro-optical modulators at optical communication wavelengths. The electro-optic effect is 123 times enhanced as compared to the bulk material as a result of the slow light effect. The transmission wavelength is found to depend linearly on the applied voltage with 1.2 nm/V modulation sensitivity. Moreover, an externally switchable dual mode regime with high quality factors and transmissions is realized. High transmissions and high quality factors are also obtained for both transverse-electric and transverse-magnetic polarizations simultaneously.

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Achieving Carrier And Photon Confinement In Ga(Nasp)/Algap/Gap Qws On Si Substrates, Ömer Lütfi̇ Ünsal, Beşi̇re Gönül Jan 2017

Achieving Carrier And Photon Confinement In Ga(Nasp)/Algap/Gap Qws On Si Substrates, Ömer Lütfi̇ Ünsal, Beşi̇re Gönül

Turkish Journal of Physics

A detailed comparative theoretical analysis on both carrier and photon confinement of dilute nitride direct bandgap GaN$_{x}$As$_{1-x-y}$P$_{y}$ with that of GaAs$_{1-y}$P$_{y}$ on Si substrates is presented. Model calculations indicate that optical confinement factor of GaAs$_{1-y}$P$_{y}$/GaP is greater than that of GaN$_{x}$As$_{1-x-y}$P$_{y}$/GaP for all concentrations. We have demonstrated that one can improve the optical confinement factor of GaN$_{x}$As$_{1-x-y}$P$_{y}$/GaP by using an Al$_{z}$Ga$_{1-z}$P cladding layer.

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Possible Variations In Sunspot Groups Before Flaring Activity During Solar Cycles 23 And 24, Ali̇ Kilçik, Seray Şahi̇n Jan 2017

Possible Variations In Sunspot Groups Before Flaring Activity During Solar Cycles 23 And 24, Ali̇ Kilçik, Seray Şahi̇n

Turkish Journal of Physics

We investigated the possible morphological variations observed in sunspot groups on the day before flaring activity occurred between January 1996 and November 2014. We found that 77% of all flaring sunspot groups were large and complex (D, E, and F modified Zurich classes). In addition, the Zurich classification of A, B, and C class sunspot groups changed more than 50%, while the remaining groups (D, E, F, and H) did not change considerably before the flare activity. Results showed that there was a remarkable increase in the sunspot areas of groups D, E, and F; in contrast, the sunspot areas …

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Lime: Semiautomated Line Measurement And Identification From Stellar Spectra, Ti̇mur Şahi̇n Jan 2017

Lime: Semiautomated Line Measurement And Identification From Stellar Spectra, Ti̇mur Şahi̇n

Turkish Journal of Physics

We present LIME (Line Measurements from ECHELLE Spectra), an IDL-based code, as a powerful tool for semiautomated stellar line measurement and identification. Interactively selected line positions (i.e. wavelengths) are compared with a master line list of the user's selections. Each unknown line that the user interactively chooses is displayed with potential identifications provided by the code in the vicinity of the selected line. The best identification is evaluated on the basis of several criteria (e.g., atomic/molecular line information, wavelength displacement, and theoretical equivalent width for solar atmospheric values). We examined the identifications by LIME in the spectra of post-red supergiant …

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Influence Of Silicon Dioxide Medium On The Structural And Electrical Properties Of Nickel Zinc Ferrite, Jacob George, Abraham Kutticheril Eapen Jan 2017

Influence Of Silicon Dioxide Medium On The Structural And Electrical Properties Of Nickel Zinc Ferrite, Jacob George, Abraham Kutticheril Eapen

Turkish Journal of Physics

Nickel zinc ferrite [(Ni$_{0.65}$Zn$_{0.35}$Fe$_{2}$O$_{4}) _{x}$ / (SiO$_{2}) _{1-x}$ where, x = 1.0, 0.85, 0.65, 0.50, 0.35, and 0.15] is synthesized using the glyoxylate precursor method. The synthesis, characterization, and electrical study of nickel zinc ferrites/SiO$_{2}$ powder with low dielectric constant, very low conductivity, and loss tangent with low frequency dispersion, suitable for good insulators, is reported here. X-ray diffraction, TGA, and FT-IR studies are employed for identifying crystalline phases and structure. Crystallite size is calculated by the Scherrer formula and Williamson--Hall equation and found to fall in the range of 4.9--25 nm. TEM of the samples shows spherical particles of …

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Effect Of Uv And Gamma Rays On Bulk Etching Of The Pokalon Track Detector, Madhusoodanan Pdmajam Gangadathan, Venkidasubramanian Sankar, Nishanth Pothiyodathu, Krishna Muraleedhara Varier Jan 2017

Effect Of Uv And Gamma Rays On Bulk Etching Of The Pokalon Track Detector, Madhusoodanan Pdmajam Gangadathan, Venkidasubramanian Sankar, Nishanth Pothiyodathu, Krishna Muraleedhara Varier

Turkish Journal of Physics

Solid-state nuclear track detectors (SSNTDs) find applications in many fields of science and technology. Polycarbonates like CR-39 or Lexan are most widely used for such applications. Pokalon is a relatively new member of the polycarbonate family of SSNTDs. It has the same monomer as that of Makrofol. In the present work we have studied the bulk etching characteristics of Pokalon at different temperatures and normalities of NaOH etchant with and without magnetic stirring. The effect of UV and gamma irradiation on the bulk etch rate has also been studied. From the bulk etch rate values at different temperatures, we have …

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Investigation Of A Novel Temperature-Sensing Mechanism Based On Strain-Induced Optical Path-Length Difference In A Multicore Optical Fiber, Belkis Gökbulut, Sema Güvenç, Mehmet Naci̇ İnci̇ Jan 2017

Investigation Of A Novel Temperature-Sensing Mechanism Based On Strain-Induced Optical Path-Length Difference In A Multicore Optical Fiber, Belkis Gökbulut, Sema Güvenç, Mehmet Naci̇ İnci̇

Turkish Journal of Physics

A four-core optical fiber is employed to investigate a novel temperature-sensing mechanism, which is based on the strain-induced optical path-length difference between the fiber core pairs. A short segment of a four-core fiber is wound around a solid stainless steel cylinder to form a tight circular loop, which is exposed to temperatures of up to 100 $^{\circ}$C. Temperature-induced radial expansion of the stainless steel cylinder causes a shear strain in the fiber and introduces an optical path-length difference between the fiber core pairs. This results in a total phase shift of about 20.40 $\pm $ 0.29 rad in the interference …

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Proton--Proton And Proton--Antiproton Differential Elastic Cross Sections Modeling At High And Ultra-High Energies Using A Hybrid Computing Paradigm, Elsayed Eldahshan Jan 2017

Proton--Proton And Proton--Antiproton Differential Elastic Cross Sections Modeling At High And Ultra-High Energies Using A Hybrid Computing Paradigm, Elsayed Eldahshan

Turkish Journal of Physics

This work presents a hybrid computing technique for modeling the differential elastic cross section of both proton--proton ``pp'' and proton--antiproton ``pp(bar)'' collisions from high to ultra-high energy regions (from 13.9 GeV to 14 TeV) as a function of the center-of-mass energy ``s'' squared and four momentum transfer squared ``t''. We proposed a genetic algorithm (GA) and support vector regression (SVR) hybrid techniques to calculate and predict the ``differential elastic cross section'' of both ``pp'' and ``pp(bar)''. Our proposed GA-SVR hybrid model shows a good match to the available experimental data, as well as predicting the latest and future ``TOTEM'' experiments …

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Marder Type Universe With Bulk Viscous String Cosmological Model In $F(R,T)$ Gravity, Sezgi̇n Aygün Jan 2017

Marder Type Universe With Bulk Viscous String Cosmological Model In $F(R,T)$ Gravity, Sezgi̇n Aygün

Turkish Journal of Physics

In this study, we have investigated homogeneous and anisotropic Marder space-time with bulk viscous string matter distribution in $f(R,T)$ gravity. For this aim we have used the anisotropy feature $(\frac{\sigma_{x}^{x} }{\theta })$ of Marder space-time and a deceleration parameter in two different $f(R,T)$ models. We have obtained bulk viscous matter distribution solutions in $f(R,T)$ gravity. Finally, some kinematical and physical properties are discussed.

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First-Principles Modeling Of Gan/Mose$_{2}$ Van Der Waals Heterobilayer, Celal Yelgel Jan 2017

First-Principles Modeling Of Gan/Mose$_{2}$ Van Der Waals Heterobilayer, Celal Yelgel

Turkish Journal of Physics

We investigate structural and electronic properties of the graphene-like gallium nitride (GaN) monolayer deposited on a MoSe$_{2}$ monolayer by using density functional theory with the inclusion of the nonlocal van der Waals correction. The GaN is bound weakly to the MoSe$_{2}$ monolayer with adsorption energy of 49 meV/atom. We find that the heterobilayer is energetically favorable with the interlayer distance of 3.302 {\AA} indicating van der Waals (vdW) type interaction and the most stable stacking configuration is verified with different deposition sequences. The heterostructure of GaN/MoSe$_{2}$ is found to be indirect band gap semiconductor with gap value of 1.371 eV. …

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Magnetized Strange Quark Matter In Reconstructed $F(R,T)$ Gravity For Bianchi I And V Universes With Cosmological Constant, Can Aktaş Jan 2017

Magnetized Strange Quark Matter In Reconstructed $F(R,T)$ Gravity For Bianchi I And V Universes With Cosmological Constant, Can Aktaş

Turkish Journal of Physics

In this article, we have investigated the behaviors of magnetized strange quark matter distributions for Bianchi I and V universes in reconstructed $f?eft( R,T \right)=\alpha_{1}R+\alpha_{2}f_{3}(T)$ gravity (here $\alpha_{1}$ and $\alpha_{2}$ are constants; $f_{3}(T)$ is an arbitrary function of $T)$. To get solutions of the field equations we have used a deceleration parameter and the equation of state for strange quark matter. The new represented $f(R,T)$ model includes two models of Harko et al. and transforms to general relativity. When $t\to ınfty $, we get the dark energy model ($p=-\rho )$ in reconstructed $f?eft( R,T \right)=\alpha _{1}R+\alpha_{2}f_{3}(T)$ gravity. However, we obtain …

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Deconvolution Analysis Of Thermoluminescent Glow Curves In Various Commercial Dosimeters Using Two Different Approaches In The Framework Of The One-Trap, One-Recombination Model, Eren Şahi̇ner Jan 2017

Deconvolution Analysis Of Thermoluminescent Glow Curves In Various Commercial Dosimeters Using Two Different Approaches In The Framework Of The One-Trap, One-Recombination Model, Eren Şahi̇ner

Turkish Journal of Physics

This paper reports kinetic analysis on the thermoluminescence (TL) glow peaks of various widespread luminescence dosimeters. A common general order kinetic (GOK) approximation and a relatively recently suggested Lambert W-function equation were used. The activation energies and the order of kinetic parameters are the main subjects of the present study. According to the results of this study, the activation energies of the main dosimetric peaks are estimated as 2.05 $\pm $ 0.11, eV, 1.23 $\pm $ 0.05 eV, and 1.11 $\pm $ 0.06 eV for LiF based dosimeters (TLD100, TLD600, TLD700), Al$_{2}$O$_{3}$:C (TLD500), and BeO dosimeters, respectively. Moreover, a number …

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Optical Visible Wavelength Region Selective Reflector Design For Photovoltaic Cells Using Photonic Crystal, Veysel Korkmaz, Ali̇ Çeti̇n Jan 2017

Optical Visible Wavelength Region Selective Reflector Design For Photovoltaic Cells Using Photonic Crystal, Veysel Korkmaz, Ali̇ Çeti̇n

Turkish Journal of Physics

In this study, we have proposed an optical broadband angular reflector having a band selective feature and high reflectivity rate for photovoltaic implementations by using a photonic crystal structure made of two different dielectric layers. This paper presents new and useful information about a reflector that was designed by using a periodic structure composed of two Si based layers for the visible range in the solar spectrum region. The system has been adjusted in such a way that it could cover a wide wavelength area between the photonic band gaps at nearly λ ≈ 300-800 nm. We have tested the …

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Monte Carlo Simulation Of A Medical Linear Accelerator For Filtered And Fff Systems, Çağri Yazğan, Yi̇ği̇t Çeçen Jan 2017

Monte Carlo Simulation Of A Medical Linear Accelerator For Filtered And Fff Systems, Çağri Yazğan, Yi̇ği̇t Çeçen

Turkish Journal of Physics

In order to simulate radiation transport, various algorithms, codes, and programs have been developed. In this study Monte Carlo N-particle code is used to simulate a medical electron linear accelerator gantry for research purposes. Detailed geometry of the LINAC head and water phantom are modeled and simulated for calculations. Analyses are made for filtered and flattening filter-free (FFF) systems. Percent depth dose and dose profile measurements are calculated with Monte Carlo simulations and compared with experimental and theoretical values for quality assurance of the model. Flux, dose, and spectrum analyses are performed for filtered and FFF systems separately. In this …

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Calculation Of The Frequency Shifts And Damping Constant For The Raman Modes (A$_{1g}$, B$_{1})$ Near The Tetragonal-Cubic Transition In Srtio$_{3}$, Ali̇ Ki̇raci, Hasan Hami̇t Yurtseven Jan 2017

Calculation Of The Frequency Shifts And Damping Constant For The Raman Modes (A$_{1g}$, B$_{1})$ Near The Tetragonal-Cubic Transition In Srtio$_{3}$, Ali̇ Ki̇raci, Hasan Hami̇t Yurtseven

Turkish Journal of Physics

Raman shifts of the soft mode A$_{1g}$ and the B$_{1}$ mode are calculated at various pressures at room temperature for the cubic-tetragonal transition (P$_{C}$ = 9.5 GPa) in SrTiO$_{3}$. This calculation is performed using the observed volume data through the mode Grüneisen parameters of A$_{1g}$ and B$_{1}$, which vary with pressure, by fitting to the experimental wavenumbers in this crystalline system. Calculated Raman shifts are then used as order parameters to predict the pressure dependence of the damping constant and the inverse relaxation time for the cubic-tetragonal transition in SrTiO$_{3}$. Our predictions from the pseudospin-phonon coupling and the energy fluctuation …

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Elastic Scattering Analysis Of $^{12}$C+$^{24}$Mg By Wkb Method, Orhan Bayrak Jan 2017

Elastic Scattering Analysis Of $^{12}$C+$^{24}$Mg By Wkb Method, Orhan Bayrak

Turkish Journal of Physics

We present the elastic scattering analysis of the $^{12}$C+$^{24}$Mg system by using the WKB approximation method within the framework of the barrier-internal wave decomposition over a wide range of energy from E$_{lab}$ = 16 MeV to 24.0 MeV. The results obtained are good agreement with the quantum mechanical (QM) calculation and experimental data.

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Synthesis Of Ni-Fe Thin Films By Electrochemical Deposition Technique And Characterization Of Their Microstructures And Surface Morphologies, Umut Saraç, Mali̇k Kaya, Mevlana Celaletti̇n Baykul Jan 2017

Synthesis Of Ni-Fe Thin Films By Electrochemical Deposition Technique And Characterization Of Their Microstructures And Surface Morphologies, Umut Saraç, Mali̇k Kaya, Mevlana Celaletti̇n Baykul

Turkish Journal of Physics

Microstructural features and surface morphologies of Ni-Fe thin films fabricated by the electrochemical deposition technique have been experimentally studied. Ni-Fe thin films have been deposited under different deposition potentials and FeSO$_{4}$ concentrations. Energy dispersive X-ray measurements demonstrate that the Fe content decreases (increases) as the deposition potential (FeSO$_{4}$ concentration) is enhanced. All of the produced films exhibit an anomalous codeposition behavior. The effects of deposition potential and FeSO$_{4}$ concentrations on the degree of anomalous codeposition have been also characterized. X-ray diffraction studies reveal that the films have face-centered cubic crystallographic structures with [111] preferred crystallographic orientation regardless of the applied …

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Quark Shapes Of Most Modern Parton Distribution Functions, Hasan Oğul Jan 2017

Quark Shapes Of Most Modern Parton Distribution Functions, Hasan Oğul

Turkish Journal of Physics

Parton distribution functions (PDFs) describe the internal structure of the proton and are necessary inputs to almost all theory predictions of hadron colliders. One way to do a precise measurement of a PDF is to measure the lepton charge asymmetry of W boson where u$\bar{d}\to W^{+}$ and $d\bar{u}\to W^{-}$. Therefore, u, d, $\bar{u}$, and $\bar{d}$ quark shapes of the most modern PDF models (NNPDF3.1, NNPDF3.0, CT14, MMHT2014, and HERAPDF2.0) are inspected using the APFEL online cluster in this paper. The ratio of $d$ to $u$ is further investigated since the charge asymmetry is sensitive to the value of $d$ over …

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Analytical Solution Of The Local Fractional Klein-Gordon Equation For Generalized Hulthen Potential, Hasi̇be Hale Karayer, Ahmet Doğan Demi̇rhan, Fevzi̇ Büyükkiliç Jan 2017

Analytical Solution Of The Local Fractional Klein-Gordon Equation For Generalized Hulthen Potential, Hasi̇be Hale Karayer, Ahmet Doğan Demi̇rhan, Fevzi̇ Büyükkiliç

Turkish Journal of Physics

The one-dimensional Klein-Gordon (KG) equation is investigated in the domain of conformable fractional calculus for one-dimensional scalar potential, namely generalized Hulthen potential. The conformable fractional calculus is based on conformable fractional derivative, which is the most natural definition in noninteger order calculus. Fractional order differential equations can be solved analytically by means of this derivative operator. We obtained exact eigenvalue and eigenfunction solutions of the local fractional KG equation and investigated the evolution of relativistic effects in correspondence with the fractional order.

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Applying A Self-Feedback Method To Control Chaos In The Buck Converter, Mei Mei Jia Jan 2017

Applying A Self-Feedback Method To Control Chaos In The Buck Converter, Mei Mei Jia

Turkish Journal of Physics

Chaos exists in the Buck converter due to the switching action of the controlled switch and this nonlinear phenomenon results in unreliable working performances. Hence, this paper uses a self-feedback control method with two adjustable parameters to suppress the chaotic behavior in the Buck converter. First, the self-feedback control method is presented by introducing a generic second-order chaotic system. Then, from the perspective of transfer functions obtained in terms of the piecewise linear model of the controlled Buck converter, effects of controller's parameters on system performances are discussed. On the basis of the Jacobian matrix of the discrete iterative mapping …

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Carbon Dioxide-Mediated Synthesis Of Pyrroles In Water, Ram Naresh Yadav, Bimal K. Banik Jan 2017

Carbon Dioxide-Mediated Synthesis Of Pyrroles In Water, Ram Naresh Yadav, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

A novel carbon dioxide-mediated synthesis of diverse pyrroles using 2,5- dimethoxytetrahydrofuran and primary amines has been achieved in excellent yield. Despite the importance of pyrroles, no study has been performed using carbon dioxide as a reagent to accomplish Paal-Knorr reaction.

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Ammonium Chloride-Induced Synthesis Of Pyrroles Via Paalknorr Reaction, Debasish Bandyopadhyay, Bimal K. Banik Jan 2017

Ammonium Chloride-Induced Synthesis Of Pyrroles Via Paalknorr Reaction, Debasish Bandyopadhyay, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Reaction of commercially available 2,5-hexanedione and primary amino compounds in the presence of ammonium chloride produced N-substituted pyrroles in excellent yield. In contrast to other available methods, this current procedure for the preparation of pyrroles is exceedingly simple, efficient, and eco-friendly and therefore, may find numerous applications in this field.

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Cyber-Security Policy Decisions In Small Businesses, Joanna Patterson Jan 2017

Cyber-Security Policy Decisions In Small Businesses, Joanna Patterson

Walden Dissertations and Doctoral Studies

Cyber-attacks against small businesses are on the rise yet small business owners often lack effective strategies to avoid these attacks. The purpose of this qualitative multiple case study was to explore the strategies small business owners use to make cyber-security decisions. Bertalanffy's general systems theory provided the conceptual framework for this study. A purposive sample of 10 small business owners participated in the interview process and shared their decision-making methodologies and influencers. The small business owners were vetted to ensure their strategies were effective through a series of qualification questions. The intent of the research question and corresponding interview questions …

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Geophysical Interpretation And Static Reservoir Modeling Of Structurally Complex Reservoir, Rg Oil Field Area, Sirte Basin, Libya, Abdalla A. Abdelnabi Jan 2017

Geophysical Interpretation And Static Reservoir Modeling Of Structurally Complex Reservoir, Rg Oil Field Area, Sirte Basin, Libya, Abdalla A. Abdelnabi

Doctoral Dissertations

"Cambrian-Ordovician and Upper Cretaceous reservoir formations are found in the central western Sirte Basin, the main oil producing region in the Sirte Basin, Libya. As a result of changes in sedimentary environments and structural activities, a number of irregularities in reservoir continuity have developed, which negatively affected the overall performance of the reservoir. Effective simulation of such complex reservoirs can be achieved by integrating geophysical, geological, and petrophysical data to construct a reliable full-field static model, which has the potential to simulate the vertical and lateral variations in the reservoir formations. In this study, 2D and 3D seismic data acquired …

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Programming Problems On Time Scales: Theory And Computation, Rasheed Basheer Al-Salih Jan 2017

Programming Problems On Time Scales: Theory And Computation, Rasheed Basheer Al-Salih

Doctoral Dissertations

"In this dissertation, novel formulations for several classes of programming problems are derived and proved using the time scales technique. The new formulations unify the discrete and continuous programming models and extend them to other cases "in between." Moreover, the new formulations yield the exact optimal solution for the programming problems on arbitrary isolated time scales, which solve an important open problem. Throughout this dissertation, six distinct classes of programming problems are presented as follows. First, the primal as well as the dual time scales linear programming models on arbitrary time scales are formulated. Second, separated linear programming primal and …

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Layered Crustal And Mantle Structure And Anisotropy Beneath The Afar Depression And Malawi Rift Zone, Cory Alexander Reed Jan 2017

Layered Crustal And Mantle Structure And Anisotropy Beneath The Afar Depression And Malawi Rift Zone, Cory Alexander Reed

Doctoral Dissertations

"Although a wealth of geophysical data sets have been acquired within the vicinity of continental rift zones, the mechanisms responsible for the breakup of stable continental lithosphere are ambiguous. Eastern Africa is host to the largest contemporary rift zone on Earth, and is thus the most prominent site with which to investigate the processes which govern the rupture of continental lithosphere. The studies herein represent teleseismic analyses of the velocity and thermomechanical structure of the crust and mantle beneath the Afar Depression and Malawi Rift Zone (MRZ) of the East African Rift System. Within the Afar Depression, the first densely-spaced …

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Efficient Algorithms For Analyzing Large Scale Network Dynamics: Centrality, Community And Predictability, Sima Das Jan 2017

Efficient Algorithms For Analyzing Large Scale Network Dynamics: Centrality, Community And Predictability, Sima Das

Doctoral Dissertations

"Large scale networks are an indispensable part of our daily life; be it biological network, smart grids, academic collaboration networks, social networks, vehicular networks, or the networks as part of various smart environments, they are fast becoming ubiquitous. The successful realization of applications and services over them depend on efficient solution to their computational challenges that are compounded with network dynamics. The core challenges underlying large scale networks, for example: determining central (influential) nodes (and edges), interactions and contacts among nodes, are the basis behind the success of applications and services. Though at first glance these challenges seem to be …

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