Dissertations / Theses on the topic 'Electrical anisotropy'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Electrical anisotropy.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Okazaki, Tomohisa. "Characteristics of Electrical Anisotropy in Magnetotelluric Responses." Kyoto University, 2018. http://hdl.handle.net/2433/232256.
Full textSomkun, Sakda. "Magnetostriction and magnetic anisotropy in non-oriented electrical steels and stator core laminations." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/55184/.
Full textVarshney, Kush R. (Kush Raj). "Joint anisotropy characterization and image formation in wide-angle synthetic aperture radar." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37852.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 145-151).
Imagery formed from wide-angle synthetic aperture radar (SAR) measurements has fine cross-range resolution in principle. However, conventional SAR image formation techniques assume isotropic scattering, which is not valid with wide-angle apertures. Also, the spatial location of scattering centers may migrate as a function of viewing angle across the aperture. The problem of jointly forming images and characterizing anisotropy as well as characterizing scattering center migration in wide-angle SAR is considered in the thesis. The approach not only compensates for anisotropy and migration in the image formation process, but gives much more information, useful for scene interpretation, than a simple image would. A method based on a sparse representation of anisotropic scattering with an over-complete basis composed of basis vectors with varying levels of angular persistence is presented. Solved as an inverse problem, the result is a complex-valued, aspect-dependent response for each scatterer in a scene. The non-parametric approach jointly considers all scatterers within one system of equations.
(cont.) The choice of the overcomplete basis set incorporates prior knowledge of anisotropy, but the method is flexible enough to admit solutions that may not match a family of parametric functions. Sparsity is enforced through regularization based on the lp quasi-norm, p < 1, leading to a non-convex minimization problem. A quasi-Newton method is applied to the problem and a novel greedy graph-structured algorithm is developed and also applied. Results are demonstrated on synthetic examples and realistic examples with XPatch data, including the backhoe public release dataset.
by Kush R. Varshney.
S.M.
Paridis, Kyriakos Costas. "The inverse conductivity problem : anisotropy, finite elements and resistor networks." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-inverse-conductivity-problem-anisotropy-finite-elements-and-resistor-networks(db58b164-9b6e-45f3-b4b9-4f5935c40e48).html.
Full textYeboah-Forson, Albert. "Hydrogeophysical Characterization of Anisotropy in the Biscayne Aquifer Using Geophysical Methods." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/919.
Full textAlmenara, Cueto Carlos Ignacio. "Anisotropy and humidity effect on tensile properties and electrical volume resistivity of fused deposition modeled acrylonitrile butadiene styrene composites." Master's thesis, Pontificia Universidad Católica del Perú, 2017. http://tesis.pucp.edu.pe/repositorio/handle/123456789/9319.
Full textIn the present thesis, the influence of anisotropy and humidity in the tensile properties and electrical volume resistivity of Acrylonitrile Butadiene Styrene/Carbon Nanotubes and Acrylonitrile Butadiene Styrene/Micro Carbon Fibers manufactured by Fused Deposition Modeling 3D printing was studied. To study the influence of the anisotropy three different layer printing orientations were compared (0°, 45° and 45°/-45°) in a layer height of 0.2 mm. It was concluded that the influence of anisotropy is important on Acrylonitrile Butadiene Styrene/Micro Carbon Fibers tensile behavior due to relation that exist between the performance/resistance and the alignment of the reinforcement. On the other hand, no significant influence was found on the Acrylonitrile Butadiene Styrene/Carbon Nanotubes. On the electrical volume resistivity, no significant variation was found on the Acrylonitrile Butadiene Styrene/Carbon Nanotubes by the anisotropy of the layers. Acrylonitrile Butadiene Styrene/Micro Carbon Fibers could not be essayed because of the high resistance of the composite. To study the influence of the humidity, two conditions on the filaments of the materials in study were compared: dry and moisture exposed. It was concluded that the influence of humidity is also remarkable on Acrylonitrile Butadiene Styrene/Micro Carbon Fibers tensile behavior because the humidity absorbed by the filaments is removed through vapor bubble blast during the 3D printing that impoverishes the adherence between the fibers and the matrix. On the other hand, no significant influence was again found on the Acrylonitrile Butadiene Styrene/Carbon Nanotubes. On the electrical volume resistivity, the humidity influences more this attributed to the less uniform structure the specimens printed with moisture exposed filaments have because of the steam explosions mentioned before.
In der vorliegenden Arbeit wurde der Einfluss von Anisotropie und Feuchtigkeit in den Zugeigenschaften und dem elektrischen Volumenwiderstand von Acrylnitril- Butadien-Styrol/Kohlenstoffnanoröhren und Acrylnitril-Butadien-Styrol/Mikro Kohlefaser, hergestellt durch Schmelzschichtung Modellieren 3D-Druck, untersucht. Um den Einfluss der Anisotropie zu untersuchen, wurden drei unterschiedliche Schichtdruckorientierungen (0 °, 45 ° und 45 ° / -45 °) in einer Schichthöhe von 0,2 mm verglichen. Es wurde festgestellt, dass der Einfluss der Anisotropie bei Acrylnitril-Butadien-Styrol/Mikro Kohlefaser zugverhalten aufgrund der Beziehung zwischen der Leistung / dem Widerstand und der Ausrichtung der Bewehrung wichtig ist. Auf der anderen Seite wurde kein signifikanter Einfluss auf die Acrylnitril- Butadien-Styrol/Kohlenstoffnanoröhren gefunden. Bei dem elektrischen Volumenwiderstand wurde keine signifikante Variation auf der Acrylnitril-Butadien-Styrol/Kohlenstoffnanoröhren durch die Anisotropie der Schichten gefunden. Acrylnitril-Butadien-Styrol/Mikro Kohlefaser konnte wegen der hohen Beständigkeit des Verbundwerkstoffes nicht aufgeschrieben werden. Um den Einfluss der Feuchtigkeit zu untersuchen, wurden zwei Bedingungen auf den Filamenten der Materialien in der Studie verglichen: trocken und Feuchtigkeit ausgesetzt. Es wurde festgestellt, dass der Einfluss der Feuchtigkeit auch bei Acrylnitril-Butadien-Styrol/Mikro Kohlefaser-Zugverhalten bemerkenswert ist, da die von den Filamenten absorbierte Feuchtigkeit durch Dampfblasenblasen während des 3D-Druckens entfernt wird, was die Haftung zwischen den Fasern und der Matrix verarmt. Auf der anderen Seite wurde auf der Acrylnitril-Butadien- Styrol/Kohlenstoffnanoröhren kein signifikanter Einfluss gefunden. Bei dem elektrischen Volumenwiderstand beeinflusst die Feuchtigkeit mehr, was auf die weniger einheitliche Struktur zurückzuführen ist. Die mit feuchtigkeitsbelichteten Filamenten bedruckten Proben haben wegen der zuvor erwähnten Dampfexplosionen.
Tesis
Wilson, Glenn Andrew, and glenn wilson@griffith edu au. "Plane Wave Propagation Problems in Electrically Anisotropic and Inhomogeneous Media with Geophysical Applications." Griffith University. School of Microelectronic Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030325.210206.
Full textWilson, Glenn Andrew. "Plane Wave Propagation Problems in Electrically Anisotropic and Inhomogeneous Media with Geophysical Applications." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/365776.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Microelectronic Engineering
Full Text
Beres, Jan. "Caractérisation de l'anisotropie d'une plate-forme carbonatée karsifiée : approche méthodologique conjointe sismique et électrique." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00880759.
Full textEl, Beainou Raya. "Relations structure - propriétés de conduction dans des films W-Cu nanostructurés." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD004/document.
Full textW and W-Cu thin films were deposited by the GLAD co-sputtering technique from two opposite targets: W and Cu. Each target was focused on the center of the substrate with a tilt angle of α = 80 °. Several series were prepared changing some experimental parameters: the sputtering pressure, the film’s thickness as well as the target currents. The nature of as-deposited films and their morphological properties were studied in order to understand the correlations between some structural characteristics and electrical behaviors of these structured films. The experimental parameters play a key-role on the shape of the columns, their angle of inclination, and the elemental composition of these W-Cu films. The influence of these parameters on the films morphology was demonstrated and related to the electronic transport properties in these columnar films. The copper was chemically etched in order to obtain a more porous structure, with the aim of improving the electrical anisotropy. A theoretical model was also developed in order to understand the electrical conductivity mechanism in these columnar films taking into account the anisotropic structure of the columns. This model was applied to W, as-deposited W-Cu and etched W-Cu films
Bouknia, M. L., C. Zebiri, D. Sayad, I. Elfergani, M. Alibakhshikenari, J. Rodriguez, Raed A. Abd-Alhameed, F. Falcone, and E. Limiti. "Analysis of the combinatory effect of uniaxial electrical and magnetic anisotropy on the input impedance and mutual coupling of a printed dipole antenna." IEEE, 2005. http://hdl.handle.net/10454/18506.
Full textThe main objective of this work is to investigate the combinatory effects of both uniaxial magnetic and electrical anisotropies on the input impedance, resonant length and the mutual coupling between two dipoles printed on an anisotropic grounded substrate. Three different configurations: broadside, collinear and echelon are considered for the coupling investigation. The study is based on the numerical solution of the integral equation using the method of moments through the mathematical derivation of the appropriate Green’s functions in the spectral domain. In order to validate the computing method and evaluated Matlab® calculation code, numerical results are compared with available literature treating particular cases of uniaxial electrical anisotropy; good agreements are observed. New results of dipole structures printed on uniaxial magnetic anisotropic substrates are presented and discussed, with the investigation of the combined electrical and magnetic anisotropies effect on the input impedance and mutual coupling for different geometrical configurations. The combined uniaxial (electric and magnetic) anisotropies provide additional degrees of freedom for the input impedance control and coupling reduction.
This work is part of the POSITION-II project funded by the ECSEL joint Undertaking under grant number Ecsel-7831132-Postitio-II-2017-IA,www. position-2.eu and partly funded by FCT/MCTES through national funds and when applicable co-funded EU funds under the project UIDB/50008/2020- UIDP/50008/2020. This work was also supported in part by the DGRSDT (General Directorate of Scientific Research and Technological Development) - MESRS (Ministry of Higher Education and Scientific Research), Algeria, and RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE).
Bouknia, M. L., C. Zebiri, D. Sayad, Issa T. Elfergani, M. Alibakhshikenari, J. Rodriguez, Raed A. Abd-Alhameed, F. Falcone, and E. Limiti. "Analysis of the combinatory effect of uniaxial electrical and magnetic anisotropy on the input impedance and mutual coupling of a printed dipole antenna." IEEE, 2021. http://hdl.handle.net/10454/18506.
Full textThe main objective of this work is to investigate the combinatory effects of both uniaxial magnetic and electrical anisotropies on the input impedance, resonant length and the mutual coupling between two dipoles printed on an anisotropic grounded substrate. Three different configurations: broadside, collinear and echelon are considered for the coupling investigation. The study is based on the numerical solution of the integral equation using the method of moments through the mathematical derivation of the appropriate Green’s functions in the spectral domain. In order to validate the computing method and evaluated Matlab® calculation code, numerical results are compared with available literature treating particular cases of uniaxial electrical anisotropy; good agreements are observed. New results of dipole structures printed on uniaxial magnetic anisotropic substrates are presented and discussed, with the investigation of the combined electrical and magnetic anisotropies effect on the input impedance and mutual coupling for different geometrical configurations. The combined uniaxial (electric and magnetic) anisotropies provide additional degrees of freedom for the input impedance control and coupling reduction.
This work is part of the POSITION-II project funded by the ECSEL joint Undertaking under grant number Ecsel-7831132-Postitio-II-2017-IA,www. position-2.eu and partly funded by FCT/MCTES through national funds and when applicable co-funded EU funds under the project UIDB/50008/2020- UIDP/50008/2020. This work was also supported in part by the DGRSDT (General Directorate of Scientific Research and Technological Development) - MESRS (Ministry of Higher Education and Scientific Research), Algeria, and RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE).
Uddin, Md Salah. "Modeling of Hexagonal Boron Nitride Filled Bismalemide Polymer Composites for Thermal and Electrical Properties for Electronic Packaging." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc955120/.
Full textBehrens, James Philip. "The detection of electrical anisotropy in 35 Ma Pacific lithosphere : results from a Marine Controlled-Source Electromagnetic survey and implications for hydration of the upper mantle /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3189793.
Full textApaydin, Nil. "Novel Implementations of Coupled Microstrip Lines on Magnetic Substrates." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1373897365.
Full textHihat, Nabil. "Modèles quasi 3D pour l'analyse de structures présentant une anisotropie 3D." Thesis, Artois, 2010. http://www.theses.fr/2010ARTO0206/document.
Full textThis thesis focuses on the analysis and the modeling the magnetic flux distribution in electrical machines with anisotropic laminated magnetic circuit. The anisotropy of magnetic sheets in transformers induces complex 3D phenomena in step-lap magnetic joints where the sheets are overlapped. Moreover, in order to increase the energy efficiency of rotating machines, new structures based on grain-oriented electrical steel are developed.However, an accurate 3D simulation of a laminated core with thin sheets and insulation of a few microns leads to very large computation time. In this context, we present a homogenization method, which purpose is to define the equivalent magnetic characteristics of any laminated core made of sheets and air gaps. Its formulation is based on the energy minimization and the magnetic flux conservation. The results of this method applied to a step-lap magnetic joint are compared with experimental measurements and a 3D finite element model. The latter requires to know the magnetic characteristics of the sheets in the rolling, transverse and normal directions. The determination of the sheets permeability in the normal direction is problematic and it constitutes an original point of our study.Two methods, analytical and numerical, based on measurements obtained with a static characterization bench makes possible the determination of the normale permeability
Linde, Niklas. "Characterization of Hydrogeological Media Using Electromagnetic Geophysics." Doctoral thesis, Uppsala universitet, Geofysik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5912.
Full textOjo, Sammy A. "Use of Compact Specimens to Determine Fracture Toughness and Fatigue Crack Growth Anisotropy of DED Additive Manufactured Ti-6Al-4V." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1597333938053578.
Full textBalog, Paul S. "High pressure and temperature electrical resistivity measurements of HCP transition metals Ti, Zr and Gd and the potential anisotropy of thermal conductivity of the inner core of the Earth." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0006/MQ30777.pdf.
Full textPera, Thierry. "Lois d'aimantation anisotropes et non linéaires : modélisation et validation expérimentale." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0038.
Full textBertram, Brian D. "Effects of interfaces and preferred orientation on the electrical response of composites of alumina and silicon carbide whiskers." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42895.
Full textKung, Christopher W. "Development of a time domain hybrid finite difference/finite element method for solutions to Maxwell's equations in anisotropic media." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1238024768.
Full textSilva, Luiz Eduardo de Lima e. "Influência da reorientação de spin nas propriedades termomagnéticas dos compostos da série Ho1-yGdyAl2." Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7012.
Full textNeste trabalho foram estudadas as propriedades estruturais e termomagnéticas dos pseudobinários Ho1-yGdyAl2, através de abordagens experimentais e teóricas. A parte experimental envolveu a preparação de cinco amostras, com as concentrações y = 0, 0,25, 0,5, 0,75 e 1, assim como medidas de magnetização, calor especifico e da variação adiabática da temperatura. Na parte teórica usamos um hamiltoniano modelo que leva em consideração a interação dos íons com o campo magnético aplicado, com o campo elétrico cristalino e a troca entre os íons magnéticos. A entropia da rede foi considerada na aproximação de Debye e a entropia eletrônica na aproximação do gás de elétrons livres. A influência das reorientações de spin, espontâneas e induzidas pelo campo magnético, na magnetização e no calor especifico foram investigadas sistematicamente tanto a partir de dados experimentais quanto teoricamente. Também obtemos resultados teóricos para a variação de entropia e variação adiabática da temperatura alterando a intensidade ou a direção do campo magnético.
In this work the structural and thermomagnetic properties of the pseudobinaries Ho1-yGdyAl2 have been studied by experimental and theoretical approaches. The experimental part included the preparation of five samples, with concentrations y = 0, 0,25, 0,5, 0,75 and 1, as well as magnetization, specific heat and adiabatic temperature change measurements. In the theoretical part we used a model Hamiltonian which includes the interaction of the ions with the applied magnetic field, the crystalline electrical field and exchange interactions with others magnetic ions. The lattice entropy has been considered within Debyes approach and the electronic entropy as that of a free electron gas. The spin reorientation influence, spontaneous and magnetic field induced ones, in magnetization and specific heat has been systematically investigated either from experimental data as well as theoretically. We have also obtained theoretical results for the isothermal entropy change and the adiabatic temperature change by modifying either the magnetic field strength or its direction.
Millan, Mirabal Leysmir Adriana. "Contribution à la caractérisation et à la modélisation 3D de l'anisotropie des aciers électriques à grains orientés en vue du calcul des pertes aux extrémités des turbo-alternateurs." Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILN013.
Full textRecently, network and transmission system operators like the European Network of Transmission System Operators of Electricity (ENTSO-E) have started to create regulations to extend the range of operation of the equipment connected to the electrical grid. The main purposes of these changes are: to increase the flexibility of the grid by making it able to withstand variations of frequency and voltage (due to alterations in the active and reactive power balance), and to ease the integration of renewable energy generation. However, many of the installed equipment connected to the grid have not been conceived to be exploited in these operating ranges and their use under these conditions will have a negative impact, especially on the turbo-generators life cycle.Large turbo-generators, used for the generation of electricity in nuclear and hydroelectric power plants, are affected by these new regulations. This impact is especially evident at end-regions of these electrical machines, where the iron losses are likely to increase significantly. These losses can lead to overheating, in particular hot points which can lead to the melting of the insulation layers between the lamination of the stator core, causing short-circuits and irreversible damage to the equipment. To be able to analyze and limit the impact of the involved physical mechanisms, the EDF Company works with tridimensional numerical simulations of the electrical machine to calculate the losses under different regimes of operation.Part of this work has already been realized in the L2EP laboratory, where the finite element analysis software code_Carmel have been adapted for the calculation of core losses and joule losses in tridimensional models. However, the physical complexity of the magnetic circuit properties at the end-regions of turbo-generators must be accounted for, in order to have reliable results. Indeed, considering the tridimensional pattern of the magnetic flux path and the strongly anisotropic properties of the magnetic circuit made from grain oriented electrical steel (GOES), the description of the iron losses requires accurate anisotropic magnetic material models combined with an efficient numerical modelling.In the framework of this PhD work, anisotropic GOES models, related to the behavior law and iron losses, have been studied and successfully implemented in a finite element method (FEM) simulation environment within the software code_Carmel. The implementation has been validated against experimental data achieved on an industrial conventional GO grade typically used in turbogenerators. Also, an experimental demonstrator has been developed to investigate more closely the magnetic behavior of a lamination stack made of GOES under non-conventional 3D magnetic flux excitations. A numerical model of the experimental demonstrator has been developed and studied with the implemented material models by comparing the global behavior of GOES as well as the iron losses in the sample of interest.The results show that under non-conventional magnetic flux attack configurations, especially with a magnetic flux attack normal to the lamination plane, the anisotropic characteristics of the GOES can influence the magnetic flux distribution within the lamination stack and the associated iron losses. In particular, the classical eddy current losses constitute, as expected, the most significant contribution of the total iron losses in the GOES laminations
Robins, P. "The use of electric potential and magnetic measurements for in vivo electrical impedance tomography of anisotropic biological tissue." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390381.
Full textOu, Runqing. "Anisotropic structure and electrical properties of intrinsically conducting polymers." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/9257.
Full textDou, Guangbin. "Mechanical and electrical characterisation of anisotropic conductive adhesive particles." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/35569.
Full textMumcu, Gokhan. "EM Characterization of Magnetic Photonic / Degenerate Band Edge Crystals and Related Antenna Realizations." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1221860344.
Full textDi, Nan. "Electric and chemical manipulation of magnetic anisotropy of ultrathin ferromagnetic films." Palaiseau, Ecole polytechnique, 2015. https://theses.hal.science/tel-01224224/document.
Full textCzerwinka, Peter Stephen. "Electrical dissipation and material properties of in-plane anisotropic superconducting YBCO films." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394861.
Full textLiu, Ming. "FINITE ELEMENT ANALYSIS OF THE CONTACT DEFORMATION OF PIEZOELECTRIC MATERIALS." UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/15.
Full textBourn, Steven. "Anisotropic behaviour of magneto-electric coupling in multiferroic composites." Thesis, University of Central Lancashire, 2018. http://clok.uclan.ac.uk/23578/.
Full textLi, Liang-shi. "Anisotropy in CdSe quantum rods." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/827094-DOIqqD/native/.
Full textPublished through the Information Bridge: DOE Scientific and Technical Information. "LBNL--55023" Li, Liang-shi. USDOE Director. Office of Science. Office of Basic Energy Sciences (US) 09/01/2003. Report is also available in paper and microfiche from NTIS.
Kim, Andrew J. "Exploring scatterer anisotrophy in synthetic aperture radar via sub-aperture analysis." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8698.
Full textIncludes bibliographical references (p. 189-193).
Scattering from man-made objects in SAR imagery exhibits aspect and frequency dependencies which are not always well modeled by standard SAR imaging techniques based on the ideal point scattering model. This is particularly the case for highresolution wide-band and wide-aperture data where model deviations are even more pronounced. If ignored, these deviations will reduce recognition performance due to the model mismatch, but when appropriately accounted for, these deviations from the ideal point scattering model can be exploited as attributes to better distinguish scatterers and their respective targets. With this in mind, this thesis develops an efficient modeling framework based on a sub-aperture pyramid to utilize scatterer anisotropy for the purpose of target classification. Two approaches are presented to exploit scatterer anisotropy using the sub-aperture pyramid. The first is a nonparametric classifier that learns the azimuthal dependencies within an image and makes a classification decision based on the learned dependencies. The second approach is a parametric attribution of the observed anisotropy characterizing the azimuthal location and concentration of the scattering response. Working from the sub-aperture scattering model, we develop a hypothesis test to characterize anisotropy. We start with an isolated scatterer model which produces a test with an intuitive interpretation. We then address the problem of robustness to interfering scatterers by extending the model to account for neighboring scatterers which corrupt the anisotropy attribution.
(cont.) The development of the anisotropy attribution culminates with an iterative attribution approach that identifies and compensates for neighboring scatterers. In the course of the development of the anisotropy attribution, we also study the relationship between scatterer phenomenology and our anisotropy attribution. This analysis reveals the information provided by the anisotropy attribution for two common sources of anisotropy. Furthermore, the analysis explicitly demonstrates the benefit of using wide-aperture data to produce more stable and more descriptive characterizations of scatterer anisotropy.
y Andrew J. Kim.
Ph.D.
Franke, Andrea Elke. "Fabrication of extremely smooth nanostructures using anisotropic etching." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10459.
Full textBasch, Russell Martin. "Evidence of anisotropic mechanical properties of fibroblast membranes." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/17224.
Full textPettis, Gregory Francis. "Hertzian dipoles and microstrip circuits on arbitrarily oriented biaxially anisotropic media." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.
Full textYoon, Im T. (Im Taek). "Anisotropy of conduction electrons in n-InSb and extrinsic and intrinsic properties of HgCdTe." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc332803/.
Full textDai, Ji-Dong. "Acoustic and optical wave propagation in anisotropic fiber waveguides." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39525.
Full textPioneer work of fundamental value on the investigation of acoustic wave propagation properties in hexagonal, trigonal and cubic fibers has also been carried out. Exact analytical solutions are achieved for acoustic wave propagation in hexagonal fibers and simplified closed form formulas are deduced for the weakly guiding case. Acoustic wave propagation in a three-layer structure consisting of a hexagonal-core, a thin isotropic interface layer and an isotropic cladding is analyzed by a perturbation method based on the exact solutions for hexagonal and isotropic acoustic fibers. Based on the exact results for acoustic wave propagation in hexagonal and isotropic fibers respectively, coupled mode equations are applied to acoustic wave propagation analyses in trigonal and cubic fibers.
Degirmenci, Evren. "High Resolution Imaging Of Anisotropic Conductivity With Magnetic Resonance Electrical Impedance Tomography (mr-eit)." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611982/index.pdf.
Full textEE MRI System and anisotropic conductivity images of test phantoms are reconstructed using all proposed algorithms.
Nardes, Alexandre Mantovani. "Condutividade de películas finas de PEDOT:PSS." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-27032015-150109/.
Full textEmploying the unique mechanical, electronic, and optical properties of the conjugated organic and polymer materials several technological and commercial applications have been developed, such as sensors, memories, solar cells and light-emitting diodes (LEDs). In this respect, the central theme of this thesis is the electrical conductivity and mechanisms of charge transport in PEDOT:PSS, a polymer blend that consists of a conducting poly(3,4-ethylenedioxythiophene) polycation (PEDOT) and a poly(styrenesulfonate) polyanion (PSS). PEDOT:PSS is omnipresent as electrode material in plastic electronics applications mentioned above. Although the conductivity of PEDOT:PSS can vary by several orders of magnitude, depending on the method by which it is processed into a thin film, the reason for this behavior is essentially unknown. This thesis describes a detailed study of the anisotropic charge transport of PEDOT:PSS and its correlation with the morphology, the shape, and the dimension of the phase separation between the two components, PEDOT and PSS. Before addressing the properties of PEDOT:PSS, a new barrier layer is described in Chapter 2 that enhances the lifetime of organic devices. An important degradation mechanism in polymer LEDs is photo-oxidation of the active layer. Hence, isolating the active layer from water and oxygen is crucial to the lifetime. Plasma-enhanced chemical vapor deposition (PECVD) is used to deposit a thin layer of carbon nitride at low deposition temperatures, below 100 °C, on a polymer LED that uses poly[2-methoxy-5-(2´-ethylhexyloxy)-1,4- phenylene vinylene] (MEH-PPV) as active layer. A thin layer of carbon nitride acts as barrier for humidity, but is still sufficiently bendable to be used in flexible polymer LEDs. The characteristics of carbon nitride and MEH-PPV films have been investigated using optical spectroscopy, with particular emphasis on the degradation process of MEH-PPV under illumination. The measurements show that the carbon nitride coating indeed protects the polymer film and diminishes the photo-oxidation considerably. To study the effect of the encapsulation in real devices, polymer LEDs were made and their current-voltage characteristics confirm the enhanced lifetime in the presence of a carbon nitride barrier layer. However, the target, a lifetime of more than 10,000 hours for commercial applications, was not achieved. The remaining chapters of this thesis describe the investigations of PEDOT:PSS. PEDOT:PSS is widely used in organic electronics. So far, relatively little attention has, been paid to the mechanisms of charge transport in this material and the correlation of those properties to the morphology. In Chapter 3, scanning probe microscopy (SPM) and macroscopic conductivity measurements are used to obtain a full 3D morphological model that explains, qualitatively, the observed anisotropic conductivity of spin coated PEDOT:PSS thin films. Topographic scanning probe microscopy (STM) and cross-sectional atomic force microscopy images (X-AFM) reveal that the thin film is organized in horizontal layers of flattened PEDOT-rich particles that are separated by quasi-continuous PSS lamella. In the vertical direction, the horizontal PSS insulator lamellas lead to a reduced conductivity and impose nearest-neighbor hopping (nn-H) transport. In the lateral direction, 3D variable-range hopping (3D-VRH) transport takes place between PEDOT-rich clusters which are separated by much thinner barriers, leading to an enhanced conductivity in this direction. This discussion is extended in Chapter 4, where a quantitative description of the length scales of the predominant transport is obtained. Particularly, it is demonstrated that the hopping process takes place between PEDOT-rich islands and not between single PEDOT segments or dopants in the lateral direction, whilst in the vertical direction the current limiting hopping transport occurs between dilute states inside the quasi-insulating PSS lamellas. By a post-treatment it is possible to modify PEDOT:PSS to raise its conductivity, by orders of magnitude. Typically, the addition of sorbitol to the aqueous dispersion of PEDOT:PSS that is used to deposit thin films via spin coating leads to an enhancement of the conductivity after thermal annealing. The causes and consequences of such behavior were investigated in detail. Chapter 5 describes the various properties of the highly conductive sorbitol-treated PEDOT:PSS, such as the conductivity itself, and the effects of thermal annealing and exposure to moisture. It is found that the conductivity enhancement upon addition of sorbitol is accompanied by a better environmental stability. Surprisingly, the electrical conductivity of PEDOT:PSS thin films without sorbitol treatment is increased by more than one order of magnitude in an environment with more than 30-35 % relative humidity. This effect is attributed to an ionic contribution to the overall conductivity. Thermal gravimetric analysis (TGA), direct insert probe-mass spectrometry (DIP-MS) and modulation differential scanning calorimetry (MDSC) were used as additional tools to demonstrate that, after thermal treatment, the concentration of sorbitol in the final PEDOT:PSS layer is negligibly small. In Chapter 6, scanning Kelvin probe microscopy (SKPM) is employed to measure the surface potential and work function of this PEDOT:PSS films that were deposited from water with different sorbitol concentrations. It is shown that work function of PEDOT:PSS is reduced with increasing sorbitol concentration. This shift can be explained by and is in agreement with- a reduction in the surface enrichment with PSS of the film. To study the charge transport properties of the highly conductive sorbitoltreated PEDOT:PSS films, temperature dependent and electric field dependent measurements are correlated with morphological analysis by STM in Chapter 7. It is found that by sorbitol treatment the hopping transport changes from 3DVRH to 1D-VRH. This transition is explained by a sorbitol-induced selforganization of the PEDOT-rich grains into 1D aggregates that are aligned within micrometer sized domains, as observed in STM images.
Nobre, Francisco Diego Martins. "Corrosão de filmes de silicio policristalino por plasma para aplicações em dispositivos MEMS e MOS utilizando misturas de gases com cloro." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259744.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-15T01:24:44Z (GMT). No. of bitstreams: 1 Nobre_FranciscoDiegoMartins_M.pdf: 7000328 bytes, checksum: ea69e5992c8dcac9e0a9aeab6ccf2ca5 (MD5) Previous issue date: 2009
Resumo: Este trabalho apresenta o desenvolvimento de processos de corrosão de filmes de silício policristalino por plasmas contendo flúor e cloro, para aplicações em dispositivos MEMS (Micro-Electro-Mechanical-Systems) e MOS (Metal Óxido Semicondutor). A corrosão foi feita em um reator RIE (Reactive Ion Etching) marca Applied Materials, modelo PE8300A. Para aplicação em MEMS foram feitas corrosões de silício policristalino, com perfis anisotrópicos e seletividade maior que 20 para óxido de silício. As misturas gasosas utilizadas na corrosão foram: Ar/SF6 e Ar/SF6/Cl2. Para avaliar melhor a evolução do perfil de corrosão, foram utilizadas amostras com filmes espessos de silício policristalino (>2 µm). Para aplicação em eletrodo de transistores MOS foi feito o afinamento de linhas de 2,5 µm para 500 nm de largura, com perfil vertical (A~0,95). Foi feita uma análise da rugosidade da superfície antes e depois dos processos de corrosão com plasma de Ar/SF6 e Ar/SF6/Cl2. Como máscara utilizaram-se linhas sub-micrométricas de platina, 300 nm de largura, depositas em equipamento FIB, sistema de feixe de íons focalizados. Foram ainda realizados processos de corrosão de dióxido de silício com plasma de misturas de Ar/SF6, objetivando altas taxas de corrosão, e de remoção de máscaras de fotorresiste com plasma de oxigênio. Os processos foram caracterizados com vários equipamentos. Um Perfilômetro foi utilizado para medir as profundidades das corrosões, para a determinação das taxas de corrosão. Um elipsômetro e um interferômetro foram utilizados nas medidas das espessuras e dos índices de refração dos filmes utilizados. Imagens SEM (Scanning Electron Microscopy) dos filmes corroídos foram feitas para analisar o perfil e determinar o mecanismo de corrosão para cada mistura, e imagens Focused Ion Beam (FIB) para analisar as estruturas sub-micrométricas.
Abstract: This work presents the results and the discussion about mechanisms of plasma etching of polysilicon and silicon films for applications in MEMS and MOS devices. The etching was performed in a conventional reactor of plasma etching, Applied Materials PE8300A model, in a RIE mode (Reactive Ion Etching). For application in MEMS, polysilicon etching with anisotropic profile and high selectivity (>20) for silicon oxide was obtained. The mixtures used in etching were SF6/Ar/Cl2 and SF6/Ar/Cl2. The evolution of the etching profile is better evaluated using polysilicon thick films (>2 µm). For application in MOS transistors electrode, 2,5 µm to 500 nm thinning was obtained with anisotropic profile (At~0,95). For surface routh analisys, before and after the etching processes in Ar/SF6 and Ar/SF6/Cl2 plasmas, sub-micrometric polysilicon lines, with platinum mask deposited by FIB, were etched. Next, silicon dioxide etching processes were executed using Ar/SF6 mixtures in order to obtain high etching rates. Finally, photoresist masks were removed without compromising the adjacent material by the use of oxygen. The films were characterized with the use of a variety of equipment. The Profiler was used to measure the etching depth, and therefore the etching rate was evaluated.
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
Cole, Jody Richard. "The effect of doping on the anisotropic electrical resistivity and thermopower of YBa₂Cu₃Ox." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597825.
Full textSchneider, Matthias. "Thermische Tieftemperatureigenschaften von Magnesium-Diborid und Seltenerd-Nickel-Borkarbiden." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1126775037525-93288.
Full textIn der vorliegenden Arbeit werden Ergebnisse von Untersuchungen an polykristallinem MgB2 sowie an YNi2B2C- und HoNi2B2C-Einkristallen analysiert. Dafür erfolgten Messungen des spezifischen elektrischen Widerstands, der Wärmeleitfähigkeit, der Thermokraft und des linearen thermischen Ausdehnungskoeffizienten. Zudem wurde die spezifische Wärmekapazität polykristalliner Borkarbide bestimmt und aus den erhaltenen Daten die Temperaturabhängigkeit der Lorenz-Zahl und des Grüneisen-Parameters sowie mittels der Ehrenfest-Relation die Druckabhängigkeit der Sprungtemperatur ermittelt. Bei tiefen Temperaturen findet man im normalleitenden Zustand für alle betrachteten Substanzen ein charakteristisches Abweichen des Widerstands vom Bloch-Grüneisen-Gesetz. Bei HoNi2B2C tritt beim antiferromagnetischen Phasenübergang im Widerstand und in der Thermokraft ein reentrant-Verhalten auf. Die thermische Leitfähigkeit von MgB2 wird unterhalb von 7 K durch die Streuung der Phononen an Korngrenzen bestimmt. Das Fehlen eines Maximums in der Wärmeleitfähigkeit im supraleitenden Zustand und einer Anstiegsänderung bei der Sprungtemperatur liefert einen Hinweis auf die Gültigkeit des Zweibandmodells, mit welchem auch der Temperaturverlauf der Wärmekapazität erklärt werden kann. Messungen der Thermokraft bestätigen den unterschiedlichen Charakter der Ladungsträger im normalleitenden Zustand der untersuchten Supraleiter, wobei Elektronendiffusion und Phonon Drag die Messdaten aller betrachteten Verbindungen in weiten Temperaturbereichen beschreiben. Für HoNi2B2C wird die thermische Ausdehnung unterhalb von 10 K durch den Beitrag der magnetischen Ordnung bestimmt. Der Grüneisen-Parameter weist für alle untersuchten Substanzen in Teilbereichen sehr große Beträge auf. Sein Temperaturverlauf hängt bei MgB2 offenbar mit Eigenschaften der maßgeblichen Phononenmode zusammen. Für die Borkarbide ist die Richtungsabhängigkeit des elektrischen Widerstandes sehr schwach, in der Wärmeleitfähigkeit hingegen recht stark ausgeprägt. Abgesehen vom antiferromagnetischen Phasenübergang bei HoNi2B2C weisen Thermokraft und Ausdehnungskoeffizient eine geringe Anisotropie auf
Barakati, Amir. "Dynamic interactions of electromagnetic and mechanical fields in electrically conductive anisotropic composites." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3562.
Full textJim, Kwok Lung. "Numerical study of in-plane optical anisotropy for GaAs/AlAs superlattice in a uniform electric field /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202002%20JIM.
Full textIncludes bibliographical references (leaves 35-37). Also available in electronic version. Access restricted to campus users.
van, den Akker Anno. "Anisotropic Thermal Physics in Suspended Black Phosphorus Thin Films." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1529066181060317.
Full textShakya, Nawayandra. "Electromagnetic Modeling of Induction Tool Responses in Isotropic and Anisotropic Layered Earth Formations." Youngstown State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1442437192.
Full textWisung, Grete. "Method evaluation : Electrical surface resistance measurements on coated conductive textiles." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-14769.
Full textLi, Bingxiang. "Electrically driven dynamic effects in nematic liquid crystals." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent156384124639024.
Full text