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Modeling At The Nanometric Scale Of Interfacial Defects Of A Semiconductor Heterostructure In The Isotropic And Anisotropic Cases For The Study Of The Influence Of Stresses, Ahmed Boussaha, Rafik Makhloufi, Rachid Benbouta, Mourad Brioua

Emirates Journal for Engineering Research

This work aims to determine the effect of stresses caused by dislocation networks placed at the interface of a semiconductor heterostructure of the thin GaAs/Si system. In this case, we use a mathematical modeling by Fourier series expansion to numerically simulate the stresses for the two cases of isotropic and anisotropic elasticity in order to predict the mechanical behavior of the heterostructure in the presence of interfacial dislocations while respecting well-defined stress boundary conditions. The elastic stress relaxation is reached for a layer thickness threshold of the GaAs deposit on the Si substrate not exceeding 5 nm.

Acoustical Properties Of Anisotropic Spinodoid Structures, Yutong Xue, Brittany Wojciechowski, Bhisham Sharma, J Stuart Bolton

Publications of the Ray W. Herrick Laboratories

Spinodoid structures, also called spinodoid metamaterials, are non-periodic cellular structures that mimic the spinodal topologies that are observed during diffusion-driven phase separation processes. Spinodoid structures are computationally efficient to model and they can be fabricated using additive techniques; as a result, they offer an attractive way to design multifunctional structures that can simultaneously provide mechanical stiffness and noise reduction performance. In recent work, the normal incidence sound absorption behavior of four distinct spinodoid topologies was studied: isotropic, cubic, columnar, and lamellar. The isotropic and cubic topologies are essentially isotropic in terms of acoustical behavior, and they can be successfully modeled …

Topological Interactions Of Spiky Particles With A Planar Wall, Elizabeth Andrew

Theses

Synthetic spiky colloids are attractive for different technologies, but quantifying the effect of orientation on the particle-surface interactions is still lacking and hinders the use of spiky colloids in different applications. This thesis tackles one of the main challenges in colloid science and engineering to describe the electrostatic and van der Waals interaction energies of a dilute suspension of spiky anisotropic colloids with a planar wall. The model reported here quantifies the DLVO interactions of a spiky particle with a planar wall, extending the surface element integration method and including the effects of particle position and orientation. The effect of …

Dual-Axis Acousto-Optic/Electro-Optic Deflectors In Lithium Niobate For Full-Parallax Holographic Video Displays, Mitchell Robert Adams

Theses and Dissertations

A major limitation of acousto-optic (AO) leaky-mode modulator based holographic displays is their inability to present full-parallax. We propose that full-parallax capabilities can be bestowed on these displays by integrating an electro-optic (EO) phased array into the architecture. We validated this concept by rendering computational models and by fabricating and testing a basic two-axis AO/EO deflector prototype in lithium niobate. This was, to our knowledge, the first instantiation of an integrated, hybrid AO/EO deflector. The prototype had a 6° deflection range along the AO-axis, and a 3° deflection range along the EO-axis. A series of models provide us with a …

Effective Anisotropic Properties-Based Representation Of Vapor Chambers, K. Baraya, J. A. Weibel, S V. Garimella

CTRC Research Publications

An easy-to-use representation of vapor chambers is developed in terms of effective anisotropic properties. This approach enables accurate simulation of the vapor chamber represented as a solid conduction block by assigning appropriate values to its effective density, specific heat, in-plane thermal conductivity, and through-plane thermal conductance. These effective properties are formulated such that the vapor chamber operation in terms of steady-state and transient thermal responses matches a full, physical simulation of phase change and energy transport in the vapor core; they are intrinsic properties that can be applied independently of the boundary conditions and heat input.

The Electronic Properties Of The Quasi-One-Dimensional Transition Metal Trichalcogenides: Tis3 And Zrs3, Simeon Gilbert

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The transition metal trichalcogenides are a class of materials formed by 1D chains of covalently bound MX₃ (M=Ti, Zr, Hf, Ta, Nb; X=S, Se, Te) trigonal prisms which are held together by weak van der Waals forces to form 2D sheets. Because of their superior edge termination, these materials suppress edge scattering effects that plague other two-dimensional materials thus enabling devices scaling to widths below 10 nm. Furthermore, this quasi-one-dimensional structure results in highly anisotropic electronic and optical properties which were examined through angle resolved photoemission spectroscopy and scanning photocurrent microscopy. These measurements show that the hole carrier masses …

Data Acquisition, Analysis, And Modeling Of Rotordynamic Systems, Michael P. Mullen

Master's Theses

Data acquisition systems for rotordynamic analysis and machine vibration were explored for the purpose of replacing the obsolete Bently Nevada ADRE 208 and ADRE for Windows system. These included the development of Matlab based custom data acquisition systems and a user interface. A model of an anisotropic rotor response undergoing transient speed was developed for the rapid prototyping and testing of data acquisition systems. Several methods for the measurement of amplitudes and phase in both the time domain and frequency domain were developed and compared. An alternate data acquisition method which is more inline with industry practices was created for …

Fluid Factor Of Fracture And Seismic Velocity Response In Anisotropic Coal Beds, Li Qin, Ma Suibo, Zhao Bin

Coal Geology & Exploration

The storage and transport of gas and water in coal seam are related to the density, strike and filler of cracks. Research on the identification and prediction of coal seam cracks will be helpful to prevent and control disastrous accidents in coal mines, such as water inrush and gas outburst. It plays an important role in the safety evaluation of coal mining. Based on the theory of fracture equivalent model, the variation characteristics of fluid factor in coal seam crevices with different fillings and fracture weaknesses parameters(fracture density, aspect ratio, volume modulus, shear modulus, Lamé parameters) are analyzed by combining …

Structural Health Monitoring Of Composite Parts: A Review, Jacob Pessin

Honors Theses

Structural health monitoring has the potential to allow composite structures to be more reliable and safer, then by using more traditional damage assessment techniques. Structural health monitoring (SHM) utilizes individual sensor units that are placed throughout the load bearing sections of a structure and gather data that is used for stress analysis and damage detection. Statistical time based algorithms are used to analyze collected data and determine both damage size and probable location from within the structure. While traditional calculations and life span analysis can be done for structures made of isotropic materials such as steel or other metals, composites …

Study Of The 3Ω Measurement Of The In-Plane And The Cross-Plane Thermal Properties On Anisotropic Thin Film Materials, Daxi Zhang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Due to the size of the nano-scale and micro-scale materials, traditional method for measuring the thermal properties of the bulk materials cannot be applied. The 3 Omega Method was developed by D. G. Cahill in the early 90s. It was used extensively to measure the thermal properties of thin film dielectric materials. Compare with other simulations or experimental methods, the 3 Omega Method has many advantages. Previous research has indicate that the 3 Omega method is capable of measuring the cross-plane thermal conductivity of thin film materials. In extension, an alternative improvement for measurement of the in-plane thermal conductivity and …

Block-Copolymer Assisted Fabrication Of Anisotropic Plasmonic Nanostructures, Calbi J. Gunder

MSU Graduate Theses

The anisotropic nanostructures of noble metals are of great interest for plasmonic applications due to the possibility of tuning the localized surface plasmon resonance (LSPR) across the UV-VIS-NIR without sacrificing the linewidth as well as to achieve larger local field enhancement. Here, we report a simple and promising fabrication method of anisotropic gold nanostructures film using polystyrene-b-2vinylpyridine (PS-b-P2VP) block copolymers (BCP) as a template. In this approach, PS-b-P2VP spherical micelles were first synthesized as a template followed by selective deposition of Au precursor inside P2VP core of the micelles using ethanol solution of Au salt. Subsequently, heat treatment of the …

Interfacial Contributions To Anomalous Hall Effect In Perpendicular Magnetic Anisotropic [Co2mnsi/Pd]3 Multilayer, Huarui Fu, Caiyin You, Li Ma, Na Tian, Fangqing Xin, Zhenxiang Cheng, Adham Basha, Amit Kohn

Australian Institute for Innovative Materials - Papers

Through engineering the interface between Co2MnSi and Pd, we realize a high perpendicular magnetic anisotropy (PMA) and controllable anomalous Hall effect (AHE) in [Co2MnSi(tCMS)/Pd]3multilayers. The multilayers are characterized by a particulatelike layer morphology following annealing at 573 K with weak B2 crystallographic ordering of the Co2MnSi layer. The largest PMA (Keff) of 1.2x106erg/cm3 has been obtained in [Co2MnSi(1.2nm)/Pd]3 multilayer annealed at 573 K. The AHE can be tuned, which we attribute to a varying proximity effect at the Co2MnSi/Pd interface, by varying the annealing temperature and Co2MnSi thickness. According to the expanded AHE scaling relation, we calculate the different contributions …

John-Stromberg Inequality For Certain Anisotropic Bmo Spaces, Yingfeng Hu

Browse all Theses and Dissertations

In this paper, we establish the John-Stromberg inequality in certain anisotropic BMO spaces and apply the inequality to anisotropic Holder continuous function spaces. To achieve this goal, we define the median value, BMO space and sharp maximal function first. Secondly we constructed a family of continuously expanding rectangles and give a Calderon-Zygmund type decomposition. By using these tools, we establish the John-Stromberg inequality. Finally, an application to anisotropic Holder continuous function spaces is presented.

Blow Up Solution Of Bose-Einstein Condensates With Anisotropic Trapping Potential And Rotation, Christopher Leonard

Electronic Theses and Dissertations

In this paper we will analyze a nonlinear Schrodinger equation with quadratic anisotropic trapping potential used to describe a Bose-Einstein condensate. We will find sufficient condition for the global existence of the solution and for the blow up result using physical properties associated to the equation such as the mass, energy, and angular momentum along with some other identities related to the equation. We will finish the thesis with showing some graphical representations describing the solution of the equation.

Analysis Of Time-Dependent Bearing Capacity Of A Driven Pile In Clayey Soils By Total Stress Method, Lin Li, Jingpei Li, De'an Sun, Weibing Gong

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This paper proposes an analytical approach to evaluate the time-dependent bearing capacity of a driven pile in clayey soils by taking the pile installation and subsequent reconsolidation effects into consideration. The process of pile installation is modeled by undrained expansion of a spherical cavity at the pile tip and a cylindrical cavity around the pile shaft. The cavity expansion solution, which is based on a K0-consolidated anisotropic modified Cam-clay model (K0-AMCC), is used to capture the pile installation effects. After pile installation, the dissipation of the excess pore water and the increase of the effective stress in the surrounding soil …

Effect Of Thermal Stress And Magnetic Field On Propagation Of Transverse Wave In An Anisotropic Incompressible Dissipative Initially Stressed Plate, M. M. Selim

Applied Mathematics & Information Sciences

In the present paper, we extend our previous work of the thermal effects on propagation of transverse waves in anisotropic incompressible dissipative pre-stressed plate, to investigate the effect of both thermal stress and magnetic field on transverse waves propagation in the medium. Biot incremental deformation theory has been used. The governing equations of transverse wave propagation are derived considering the magnetic forces applied on the plate through Maxwell equation. The influences of changes in anisotropy-type, thermal stress, initial stresses and magnetic field are investigated. The velocities of propagation as well as damping are discussed. Analytical analysis and Numerical computations reveal …

Computational Wave Field Modeling Using Sequential Mapping Of Poly-Crepitus Green’S Function In Anisotropic Media, Sajan Shrestha

Theses and Dissertations

In this thesis, a meshless semi-analytical computational method is presented to compute the ultrasonic wave field in the generalized anisotropic material while understanding the physics of wave propagation in detail. To understand the wave-damage interaction in an anisotropic material, it is neither feasible nor cost-effective to perform multiple experiments in the laboratory. Hence, recently the computational nondestructive evaluation (CNDE) received much attention to performing the NDE experiments in a virtual environment. In this thesis, a fundamental framework is constructed to perform the CNDE experiment of a thick composite specimen in a Pulse-Echo (PE) mode. To achieve the target, the following …

Improving The Mechanical Performance Of 3d Printed Parts Using Fused Filament Fabrication, Inderpreet Binning

Industrial and Manufacturing Engineering

The 3D printing industry has seen rapid growth in the last 10 years and has been called the next industrial revolution. There are several different processes used in 3D printing, but the most popular process is called Fused Filament Fabrication (FFF) or Fused Deposition Modeling (FDM). This is the process where (most commonly) plastic filament enters a nozzle, is heated to a semi-liquid state, and then deposited into a pattern to create a print. One major drawback to this process is that the prints are anisotropic. This means that the strength of the print varies with the orientation that it …

Thermal Effects On Propagation Of Transverse Waves In Anisotropic Incompressible Dissipative Pre-Stressed Plate, M. M. Selim

Applied Mathematics & Information Sciences

In this paper an attempt has been made to find a simple form of the thermal effects on transverse waves propagating in an anisotropic incompressible dissipative pre-stressed plate in the context of Biot’s theory. The governing equations are derived and the velocities of propagation as well as damping are discussed. The influences of changes in anisotropy-type, initial and thermal stresses are discussed. Analytical analysis reveals that the velocities of the transverse waves depend upon the anisotropy as well as the initial and thermal stresses present in the medium. Numerical computation shows that the variation in the parameters associated with anisotropy …

Co-Orthologs Of Katanin1 Impact Plant Morphology And Show Differential Evolution In Maize, Kin Ho Lau

Open Access Dissertations

Understanding how the size and shape of crop plants and their specific organs are genetically controlled may allow for the development of cultivars with improved plant architecture. A microtubule-severing enzyme called katanin p60 is encoded by KATANIN1 (KTN1) in Arabidopsis or by an ortholog, dwarf and gladius leaf1 (dgl1), in rice. Katanin p60 has been implicated in the control of anisotropic cell growth, which is cell growth directed in a specific direction instead of equally in all directions. Anisotropic cell growth is crucial for proper plant shape and its disruption in ktn1/dgl1 mutants leads to morphological changes such as stunted …

Electromagnetic Field And Rotation Effects On S-Waves Propagation In A Non-Homogeneous Anisotropic Incompressible Medium Under Initial Stress And Gravity Field, S. M. Abo-Dahab

Applied Mathematics & Information Sciences

In this paper, shear waves propagation in a non-homogeneous anisotropic incompressible medium under influence of the electromagnetic field, gravity field, rotation and initially stressed medium has been studied. Analytical analysis reveals that the velocity of propagation of the shear waves depends upon the direction of propagation, the anisotropy, magnetic field, rotation, gravity field, non-homogeneity of the medium, and the initial stress. The frequency equation that determines the velocity of the shear waves has been obtained. The dispersion equations have been obtained and investigated for different cases. In fact, these equations are an agreement with the corresponding classical results when the …

Anisotropic Electrical Response Of Carbon Fiber Reinforced Composite Materials, Mohammad Faisal Haider

Theses and Dissertations

Composites materials are often subjected to multi-physical conditions in different applications where, in addition to mechanical loads, they also need to sustain other types of loads such as electrical currents. The multi-physical behavior of composites needs to be understood and analyzed to facilitate new multi-functional material design. An essential first step towards this goal is to understand how multi-physics properties depend on local details (e.g. micro-structure). Composite materials have heterogeneous electrical properties (carbon/epoxy) at the local level that can be different at the global level. To conduct the multi-physics study, the electrical signal is employed to the composite sample for …

Sub-Millisecond Measurements Of Thermal Conductivity And Thermal Diffusivity Using Micrometer-Sized Hot Strips, Mattias K. Gustavsson, Johan S. Gustavsson, Yi Ma, Åsa Haglund, Daniel Cederkrantz, Silas E. Gustafsson

International Thermal Conductivity Conference (ITCC) and the International Thermal Expansion Symposium (ITES)

A new measurement technique based on the transient hot strip technique has recently been developed for studying anisotropic thermal transport properties of thin crystalline films. A micrometer-sized hot strip sensor is evaporated on the surface of the crystalline film sample, which has been deposited on a substrate wafer of limited thickness. From a pulsed transient recording, using sub-millisecond square-shaped pulses, a thermal probing depth that is less than the film thickness is assured. In the ongoing work of verifying the technique, we show results from measurements on z-cut crystal quartz and fused silica, using thermal probing depths of only 30 …

Formulation Of Cross-Anisotropic Failure Criterion For Soils, Yi-Fei Sun, Han-Long Liu, Gui Yang, Yang Xiao

Yang Xiao

Inherently anisotropic soil fabric has a considerable influence on soil strength. To model this kind of inherent anisotropy, a three-dimensional anisotropic failure criterion was proposed, employing a scalar-valued anisotropic variable and a modified general threedimensional isotropic failure criterion. The scalar-valued anisotropic variable in all sectors of the deviatoric plane was defined by correlating a normalized stress tensor with a normalized fabric tensor. Detailed comparison between the available experimental data and the corresponding model predictions in the deviatoric plane was conducted. The proposed failure criterion was shown to well predict the failure behavior in all sectors, especially in sector II with …

Coupled Gradient Enhanced Damage - Viscoplasticity Model Using Phase Field Method, Navid Mozaffari

LSU Doctoral Dissertations

The aim of this dissertation is developing a framework to describe damage evolution as a phase transformation in solid materials and couple it to the well-known Perzyna type viscoplastic model to account for inelastic behavior of ductile materials. To accomplish this task, the following steps have been performed. First, a new nonlocal, gradient based damage model is proposed for isotropic elastic damage using the phase field method in order to show the evolution of damage in brittle materials. The general framework of the phase field model (PFM) is discussed and the order parameter is related to the damage variable in …

Exchange Interaction Mediated Ferroelectricity In Multiferroic Mntio3 With Anisotropic Orbital Hybridization And Hole Delocalization, Shiwei Chen, Paoan Lin, Horngtay Jeng, S W. Fu, Jennmin Lee, Jyhfu Lee, Chihwen Pao, Hirofumi Ishii, Kuding Tsuei, Nozomu Hiraoka, Dapeng Chen, S X. Dou, Xiaolin Wang, Kueihtzu Lu, Jinming Chen

Shi Xue Dou

We present the orbital structure of MnTiO3 with polarization dependent x-ray absorption and resonant x-ray emission spectra accompanied with electronic structure calculations. The results clearly indicate a strongly anisotropic O 2p-Mn 3d orbital hybridization whereas the Mn 3d hole state shows a highly delocalized characteristic ascribed to the 3d-4p mixing. The extended Mn 4p orbital could enhance the exchange interaction between Mn (3d)-O (2p)-Mn (3d) leading to an asymmetric charge distribution in Mn-O bonds. The delocalized characteristic of Mn 3d holes is indispensable to the mechanism of spin-dependent-metal-ligand hybridization to explain magnetically induced ferroelectricity.

Anisotropic Magnetoresistance In Antiferromagnetic Sr2Iro4, C. Wang, H. Seinige, Gang Cao, J.-S. Zhou, J. B. Goodenough, M. Tsoi

Physics and Astronomy Faculty Publications

We report point-contact measurements of anisotropic magnetoresistance (AMR) in a single crystal of antiferromagnetic Mott insulator Sr₂IrO₄. The point-contact technique is used here as a local probe of magnetotransport properties on the nanoscale. The measurements at liquid nitrogen temperature reveal negative magnetoresistances (up to 28%) for modest magnetic fields (250 mT) applied within the IrO₂ a−b plane and electric currents flowing perpendicular to the plane. The angular dependence of magnetoresistance shows a crossover from fourfold to twofold symmetry in response to an increasing magnetic field with angular variations in resistance from 1% to 14%. We …

Dyadic Green's Functions For Layered General Anisotropic Media And Their Application To Radiation Of Dipole Antennas, Ying Huang

Dissertations - ALL

In this dissertation, the dyadic Green‟s functions (DGFs) for unbounded and layered anisotropic media, with no restriction imposed on the medium property, are derived. Utilizing the obtained DGFs, the radiation problems of a Hertzian dipole and a microstrip antenna in the presence of an anisotropic substrate are solved.

After a brief introduction, the eigenvector dyadic Green‟s functions (E-DGFs) for an unbounded general anisotropic medium through the eigen-decomposition method are derived. The E-DGFs of a layered anisotropic geometry are then constructed based on the derivation of the unbounded E-DGFs using two different approaches. One is through the symmetrical property of the …

Synthesis, Processing And Characterization Of Polymer Derived Ceramic Nanocomposite Coating Reinforced With Carbon Nanotube Preforms, Hongjiang Yang

Electronic Theses and Dissertations

Ceramics have a number of applications as coating material due to their high hardness, wear and corrosion resistance, and the ability to withstand high temperatures. Critical to the success of these materials is the effective heat transfer through a material to allow for heat diffusion or effective cooling, which is often limited by the low thermal conductivity of many ceramic materials. To meet the challenge of improving the thermal conductivity of ceramics without lowering their performance envelope, carbon nanotubes were selected to improve the mechanical properties and thermal dispersion ability due to its excellent mechanical properties and high thermal conductivity …

Exchange Interaction Mediated Ferroelectricity In Multiferroic Mntio3 With Anisotropic Orbital Hybridization And Hole Delocalization, Shiwei Chen, Paoan Lin, Horngtay Jeng, S W. Fu, Jennmin Lee, Jyhfu Lee, Chihwen Pao, Hirofumi Ishii, Kuding Tsuei, Nozomu Hiraoka, Dapeng Chen, S X. Dou, Xiaolin Wang, Kueihtzu Lu, Jinming Chen

Australian Institute for Innovative Materials - Papers

We present the orbital structure of MnTiO3 with polarization dependent x-ray absorption and resonant x-ray emission spectra accompanied with electronic structure calculations. The results clearly indicate a strongly anisotropic O 2p-Mn 3d orbital hybridization whereas the Mn 3d hole state shows a highly delocalized characteristic ascribed to the 3d-4p mixing. The extended Mn 4p orbital could enhance the exchange interaction between Mn (3d)-O (2p)-Mn (3d) leading to an asymmetric charge distribution in Mn-O bonds. The delocalized characteristic of Mn 3d holes is indispensable to the mechanism of spin-dependent-metal-ligand hybridization to explain magnetically induced ferroelectricity.