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Probabilistic Engineering Analysis And Design Under Time-Dependent Uncertainty, Zhen Hu

Doctoral Dissertations

"Time-dependent uncertainties, such as time-variant stochastic loadings and random deterioration of material properties, are inherent in engineering applications. Not considering these uncertainties in the design process may result in catastrophic failures after the designed products are put into operation. Although significant progress has been made in probabilistic engineering design, quantifying and mitigating the effects of time-dependent uncertainty is still challenging. This dissertation aims to help build high reliability into products under time-dependent uncertainty by addressing two research issues. The first one is to efficiently and accurately predict the time-dependent reliability while the second one is to effectively design the time-dependent …

Modeling And Optimization Of Energy Storage System For Microgrid, Xin Qiu

Doctoral Dissertations

"The vanadium redox flow battery (VRB) is well suited for the applications of microgrid and renewable energy. This thesis will have a practical analysis of the battery itself and its application in microgrid systems. The first paper analyzes the VRB use in a microgrid system.

The first part of the paper develops a reduced order circuit model of the VRB and analyzes its experimental performance efficiency during deployment. The statistical methods and neural network approximation are used to estimate the system parameters. The second part of the paper addresses the implementation issues of the VRB application in a photovoltaic-based microgrid …

Energy Aware And Privacy Preserving Protocols For Ad Hoc Networks With Applications To Disaster Management, Mayank Raj

Doctoral Dissertations

"Disasters can have a serious impact on the functioning of communities and societies. Disaster management aims at providing efficient utilization of resources during pre-disaster (e.g. preparedness and prevention) and post-disaster (e.g. recovery and relief) scenarios to reduce the impact of disasters. Wireless sensors have been extensively used for early detection and prevention of disasters. However, the sensor's operating environment may not always be congenial to these applications. Attackers can observe the traffic flow in the network to determine the location of the sensors and exploit it. For example, in intrusion detection systems, the information can be used to identify coverage …

Investigation Of Projectile Coherence Effects In Fully Differential Studies Of 75 Kev Proton - H₂ Collisions, Sachin Sharma

Doctoral Dissertations

"Fully differential cross sections (FDCS) have been measured for single ionization of H₂ by 75 keV proton impact with varying transverse coherence length of the projectiles. As reported in recent years, the scattering angle dependence of the doubly differential cross sections (DDCS) are significantly affected by the projectile coherence properties. The interference structures were observed for the coherent beam, however were absent for an incoherent beam. Interestingly, the FDCS measurements for fixed momentum transfer do not suggest significant differences between the coherent and incoherent cross sections. However, for the FDCS with fixed recoil-ion momentum, clear differences between the two …

Thermal-Fluid Modeling Of The Missouri S&T Reactor, Susan Maria Sipaun

Doctoral Dissertations

"Thermal-fluid modeling of the Missouri University of Science and Technology Reactor (MSTR) was carried out using a computational fluid dynamics code (CFD), STAR-CCM+. First, a three-dimensional parallel-plate model was developed, and the cosine-shaped heat flux was applied to the MSTR core. Simulation results for fluid flow under natural convection condition show coolant temperature and velocity as a function of core power. A characteristic equation for the parallel-plate model was obtained based on Forchheimer's flow equation. The inertial resistance tensor and viscous resistance tensor were found to be 281005 kg/m^4 and 7121.6 kg/m^3 respectively. The MSTR core was then defined as …

Part I: In-Situ Fluorometric Quantification Of Microalgal Neutral Lipids Part Ii: Thermal Degradation Behavior Of Investment Casting Polymer Patterns, Hongfang Zhao

Doctoral Dissertations

"Research described in this dissertation covers two topics. Part-I is focused on in-situ determination of neutral lipid content of microalgae using a lipophilic fluorescent dye. The traditional Nile red stain-based method for detecting microalgal intracellular lipids is limited due to varying composition and thickness of rigid cell walls. In this study, the addition of dilute acid and heating of solution, were found to greatly enhance staining efficiency of Nile red for microalgal species evaluated. Oil-in-water (O/W) microemulsion stabilized by a non-ionic surfactant was employed as a pseudo-standard that mimics lipid-bearing microalgal cells suspended in water. The average neutral lipid contents …

Semiconductor Nanocrystals For Novel Optical Applications, Jong-Sik Moon

Doctoral Dissertations

“Inspired by the promise of enhanced spectral response, photorefractive polymeric composites photosensitized with semiconductor nanocrystals have emerged as an important class of materials. Here, we report on the photosensitization of photorefractive polymeric composites at visible wavelengths through the inclusion of narrow band-gap semiconductor nanocrystals composed of PbS. Through this approach, internal diffraction efficiencies in excess of 82%, two-beam-coupling gain coefficients in excess of 211 cm^-1, and response times 34 ms have been observed, representing some of the best figures-of-merit reported on this class of materials. In addition to providing efficient photosensitization, however, extensive studies of these hybrid composites …

Advanced Active Rectifiers For Electric Vehicle Battery Charging, Darren Lee Paschedag

Doctoral Dissertations

"In a big picture sense, the work presented in this dissertation is in the area of fully electric or plug-in hybrid electric vehicles. Both of these vehicle types require an external power source to fully charge their large amount of energy storage. For most consumers this means plugging their vehicle into the utility which necessitates battery charging circuitry. More specifically, this dissertation focuses on the power factor correction (PFC) circuit which makes up one part of a typical battery charging system. The circuits presented here are not dependent on battery chemistry, so they can be utilized with all popular chemistries …

Modeling And Simulation Of Continuous Fiber-Reinforced Ceramic Composites, Venkata Bheemreddy

Doctoral Dissertations

"Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior …

Bioactive Glass/Polymer Composites For Bone And Nerve Repair And Regeneration, Ali Mohammadkhah

Doctoral Dissertations

"Bioactive glasses have several attractive properties in hard and soft tissue repair but their brittleness limited their use, as scaffolding materials, for applications in load- bearing hard tissue repair. At the same time, because of their bioactive properties, they are being studied more often for soft tissue repair. In the present work, a new glass/polymer composite scaffold was developed for the repair of load-bearing bones with high flexural strength and without brittle behavior. The new composites have 2.5 times higher flexural strength and ~100 times higher work of fracture (without catastrophic failure) compared to a similar bare glass scaffold.

Also …

Electric-Drive Vehicle Emulation Using Advanced Test Bench, Poria Fajri

Doctoral Dissertations

"Vehicle electrification is considered to be the most promising approach toward addressing the concerns on climate change, sustainability, and rapid depletion of fossil fuel resources. As a result electric-drive vehicle (EDV) technology is becoming the subject of many research studies, from academia and research laboratories to automotive industries and their suppliers. However, a crucial step toward the success of EDV implementation is developing test platforms that closely emulate the behavior of these vehicles.

In this dissertation, a new approach for emulating an EDV system on a motor/dynamometer test bench is investigated. Two different methods of emulation are discussed which are …

Automated Classification Of Malignant Melanoma Based On Detection Of Atypical Pigment Network In Dermoscopy Images Of Skin Lesions, Nabin K. Mishra

Doctoral Dissertations

“Melanoma causes more deaths than any other form of skin cancer. Early melanoma detection is important to prevent progression to a more deadly stage. Automated computer-based identification of melanoma from dermoscopic images of skin lesions is the most efficient method in early diagnosis. An automated melanoma identification system must include multiple steps, involving lesion segmentation, feature extraction, feature combination and classification. In this research, a classifier-based approach for automatically selecting a lesion border mask for segmentation of dermoscopic skin lesion images is presented. A logistic regression based model selects a single lesion border mask from multiple border masks generated by …

Degradable Nanocomposite Preformed Particle Gel For Chemical Enhanced Oil Recovery Applications, Paul Tongwa

Doctoral Dissertations

”This work presents two new materials that can be potentially used in conformance control to increase ultimate oil recovery from mature oilfields.

The first product is a degradable nanocomposite preformed particle gel for enhanced in-depth mobility control. Three different types of degradable nanocomposite preformed particle gels were synthesized. These three nanocomposite hydrogels were made using Laponite XLG, Calcium Montmorillonite, and Sodium Montmorillonite nanomaterials. It was observed that after degradation, Laponite XLG nanocomposite hydrogels had the highest post-degradation viscosity (4437 cp), followed by sodium nanocomposite hydrogels (129 cp), and lastly calcium nanocomposite hydrogels (75.5 cp). Thus, degradable Laponite XLG nanocomposite hydrogels …

Georgia Southern Magazine, Georgia Southern University

Georgia Southern Magazine

• One Student Body
• Perfect Landing
• Achilles Strong
• Young Perspective
• All for Love

Georgia Southern Magazine, Georgia Southern University

Georgia Southern Magazine

• Blink of an Eye
• First Class
• Double Major
• The Ride

Traceability Implementation In Organic Farming: Case Study, Chamomile Tea Production, Shaima Ibrahim

Theses and Dissertations

Implementing a traceability plan in an herbal production plant is a complex task. In this study an attempt to integrate food safety, quality and traceability through the different stages of the organic German Chamomile (Matricaria recutita) production chain was made. First, all the current relevant international laws, regulations and standards regarding traceability, safety and quality, with emphasis on how and why they are necessary for any food production chain, were set forward. Second, physico-chemical and microbiological analyses were run throughout the different processing stages of production, for four different Chamomile batches produced over the same season using the same farming …

Gera Conference Program [2014], Georgia Educational Research Association

Georgia Educational Research Association Conference

N/A

The Results Of The First Photonuclear Reaction Performed In Turkey: The Zinc Example, İsmai̇l Boztosun, Haris Dapo, Süleyman Fati̇h Özmen, Yi̇ği̇t Çeçen, Mesut Karakoç, Abdullah Çoban, Alp Cesur, Tanfer Caner, Edi̇p Bayram, Gi̇zem Büşra Keller, Beyza Küçük, Abdullah Güvendi̇, Melek Derman, Deni̇z Kaya

Turkish Journal of Physics

We have investigated the decays of several zinc isotopes produced by photonuclear reactions, which were induced by bremsstrahlung photon beams from a clinical e-linac. A photon beam of 18 MeV endpoint energy was directed at a target consisting of primarily zinc isotopes in their natural abundances. Subsequently, the induced decays of unstable zinc isotopes were measured with an HPGe detector twice, once shortly after irradiation and once on the following day. Decays of Zn-63, Zn-65, Zn-69m, and Cu-67 were measured and fitted. In addition, the gamma energy levels of the daughters of these decays were measured with good accuracy. All …

Evidence That Photons Have Extension In Space, Randy Wayne

Turkish Journal of Physics

Satyendra Nath Bose realized that there was a logical inconsistency in the derivation of Planck's radiation law since the derivation used to obtain the temperature-independent prefactor in the blackbody radiation law had been based in part on classical wave hypotheses, such as the number of degrees of freedom of the ether. Bose worked out a strictly quantum derivation by combining the quantum hypothesis with statistical mechanics to determine the number of states of each mode that would occupy a 6-dimensional phase space. Here I use the model of an extended photon to show that the temperature-independent prefactor of Planck's radiation …

Soret And Dufour Effects On An Mhd Free Convective Flow Through A Channel Bounded By A Long Wavy Wall And A Parallel Flat Wall, Nazibuddin Ahmed, Kalpana Sarma, Hiren Deka

Turkish Journal of Physics

This paper presents Soret and Dufour effects on a 2-dimensional free convective magnetohydrodynamic (MHD) flow of a viscous incompressible and electrically conducting fluid through a channel bounded by a long vertical wavy wall and a parallel flat wall. A uniform magnetic field is assumed to be applied perpendicular to the flat wall. Governing equations of the fluid flow and heat and mass transfer are solved analytically subject to the relevant boundary conditions. It is assumed that the solution consists of 2 parts, a mean part and a perturbed part. The long wave approximation has been used to obtain the solution …

Influence Of Composition On The Structure And Optoelectronic Properties Of Pb_Xin_{25-X}Se_{75} Thin Films, Hesham Azmi Elmeleegi, Zeinab El Sayed El Mandouh, Ahmed Abdel Moez

Turkish Journal of Physics

Pb_xIn_{25-x}Se_{75} thin films with 2 compositions were prepared by thermal evaporation. The surface topography of these films was studied by transmission electron microscope. The optical reflectance and transmittance were studied in order to determine the optical parameters such as optical energy gap, refractive index, extinction coefficient, dielectric loss, and dielectric tangent loss for these films. A single oscillator theory equation was applied for these films in order to determine both dispersion energy and oscillating energy, and the ratio of free carrier concentration/effective mass (N/m*) was determined optically. It was found that change in the composition of these films affects strongly …

Representation Of Electromagnetic And Gravitoelectromagnetic Poynting Theorems In Higher Dimensions, Mustafa Emre Kansu, Murat Tanişli, Süleyman Demi̇r

Turkish Journal of Physics

This study investigates whether the electromagnetic and gravitoelectromagnetic energy conservation equations are obtained together by using octonion algebra or not. Maxwell and Maxwell-like equations for linear gravity with magnetic monopole terms are used in the SI unit system. A new complex octonionic field term is suggested for the first time. The complex octonionic source equation is then obtained. Finally, Poynting theorems for both electromagnetism and gravitoelectromagnetism are defined for the first time by using higher dimensional algebra.

Fast Numerical Algorithm For A High-Precision 6d Electromagnetic Positioning Navigation System, Qian Xiang, Shiqing Wang, Haifeng Liu

Turkish Journal of Physics

A fast numerical algorithm is proposed for the 6 degrees of freedom electromagnetic navigation system, which can be used to improve surgical operations guided by medical images. Both the rotation transformation technique and optimization technique are adopted in the algorithm. The results from simulations show that the calculating time is improved greatly under the required precision in the surgery. A navigation system based on the algorithm can make the medical device's dimensions miniaturized and the structure simplified and portable. The performance and application scope of the electromagnetic positioning navigation system can be improved.

Octonion Symmetric Dirac-Maxwell Equations, Bhupesh Chandra Chanyal

Turkish Journal of Physics

We know that the octonion algebra is the largest division algebra. Therefore, we have discussed the octonion 8-dimensional space as the combination of 2 (external and internal) 4-dimensional spaces. The octonion wave equations in terms of 8 components has been written in terms of an 8 x 8 matrix. Octonion forms of potential as well as fields equations of dyons in terms of an 8 x 8 matrix are discussed in a consistent manner. At last, we have obtained the generalized Dirac-Maxwell equations of dyons in two 4-dimensional spaces, from the 8 x 8 matrix representation of octonion wave equations. …

Magnetized Kantowski-Sachs Bulk Viscous String Cosmological Models With Decaying Vacuum Energy Density Lambda (T), Kanika Das, Nawsad Ali

Turkish Journal of Physics

In this paper, we deal with bulk viscous magnetized Kantowski-Sachs string cosmological models in the presence of time variable cosmological term Lambda . To obtain a deterministic model, we assume the conditions sigma infty theta and zeta theta = constant, where sigma is the shear, theta the expansion in the model, and zeta the coefficient of bulk viscosity. The value of cosmological constant for the models is found to be small and positive, which is supported by the results from recent observations (SN 1a). The behavior of the model in the presence and absence of magnetic fields together with physical …

Annealing Effect On Zinc Nanoferrite Particles Synthesized By Spray Pyrolysis Of Polymer Precursor, Jessyamma Kurian, Subin John, Jacob Mathew

Turkish Journal of Physics

Nanosized zinc ferrite particles, prepared by spray pyrolysis method, were investigated by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, Fe^{57} Mossbauer spectroscopy, and vibrating sample magnetometer. The cubic crystalline phases were identified in all samples. The lattice parameter (a = 8.446 Å) and the average particle size of all the samples were determined. The particle sizes increased as the annealing temperature increased from 250 °C to 550 °C. The variation in structural parameters and particle size estimated from X-ray diffraction patterns of heat-treated samples suggested that the synthesized sample was in a `metastable' state or a compositionally constrained state. …

Uv-Vis And Xrd Investigation Of Graphite-Doped Poly(Acrylic) Acid Membranes, Mihai Todica, Traian Stefan, Simion Simon, Istvan Balasz, Liviu Daraban

Turkish Journal of Physics

Possible modification of the structure of poly(acrylic) acid (PAA) membranes doped with graphite was investigated by UV-Vis and XRD techniques. The pure PAA membranes were characterized by good transparency in the domain 250-700 nm, with maximum absorption at 207 nm. The absorbance of membranes increased significantly after doping with graphite. The XRD patterns of pure membranes showed a low degree of order of the polymeric matrix. Some modifications of the parameters of the ordered domains of the polymer and of the graphite appeared at high concentrations of the dopant.

Saga Of Efficiency Degradation At High Injection In Ingan Light Emitting Diodes, Vitaliy Avrutin, Shopan A. Hafiz, Fan Zhang, Ümi̇t Özgür, Enrico Bellotti, Francesco Bertazzi, Michele Goano, Arvydas Matulionis, Adam T. Roberts, Henry O. Everitt, Hadis Morkoç

Turkish Journal of Physics

No abstract provided.

Extended Defects In Gan Nanocolumns Characterized By Cathodoluminescence Directly Performed In A Transmission Electron Microscope, Frank Bertram, Marcus Müller, Gordon Schmidt, Peter Veit, Jürgen Christen, Arne Urban, Joerg Malindretos, Angela Rizzi

Turkish Journal of Physics

Using cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope at liquid helium temperature, the structural and optical properties of GaN nanocolumns, in particular extended defects like stacking faults and dislocations, have been characterized. The influence of the crystalline real structure on the emission properties using the capability of addressing individual stacking faults is comprehensively examined.

A Study On Si And P Doped H-Bn Sheets: Dft Calculations, Hati̇ce Kökten, Şaki̇r Erkoç

Turkish Journal of Physics

Structural properties and energetics of silicon and phosphorus doped hexagonal boron nitride sheets were investigated by performing density functional theory calculations. The dopant atoms were substituted in a neutral charge state at either the B or the N site in the system as an impurity. All the systems under consideration were fully optimized. A systematic study was performed to see the effect of cell size on the calculated quantities, such as bond length, charge transfer, and defect formation energies. It was found that both silicon and phosphorus atom substitutions cause the bond lengths to increase with respect to the pristine …