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Mallan, Robert Keays 1968. "Model studies of radio frequency electromagnetic geotomography." Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/278551.
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The objectives of this research were to provide accurate geotomography data and to subsequently use these data to investigate the ability of a two dimensional (2-D), rigorous wave equation model to describe the data. This was approached by constructing a physical, scale model EM tomography system to make measurements over a known, controllable medium. These data were used in the evaluation of a 2-D, exact, integral wave equation model as part of a reconstruction algorithm to image the conductivity and permittivity distribution of the planar region under investigation. Measured data exhibited precision, symmetry and repeatability, and also accuracy in determining the conductivity and permittivity of an aqueous solution. Analysis of the data indicates that the tomography system can detect and accurately locate a target. Adjustments in the 2-D mathematical model were needed in order to accurately fit the radiation pattern of the electric dipole antenna used in the physical scale model. Subsequently, the 2-D model was able to successfully describe tomography data over a 2-D target.
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Agutu, Willis Owuor Mr. "Characterization of electromagnetic induction damper." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1187267117.
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Krueger, Kyle R. "Model design for algorithmic efficiency in electromagnetic sensing." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50402.
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The objective of the proposed research is to develop structural changes to the design and application of electromagnetic (EM) sensing models to more efficiently and accurately invert EM measurements to extract parameters for applications such as landmine detection. Two different acquisition modalities are addressed in this research: ground-penetrating radar (GPR) and electromagnetic induction (EMI) sensors. The models needed for practical three-dimensional (3D) spatial imaging typically become impractically large, with up to seven dimensions of parameters that need to be extracted. These parameters include, but are not limited to target type, 3D location, and 3D orientation. The new special structures for these models exploit properties such as shift invariance and tensor representation, which can be combined with strategic inversion techniques, including the Fast Fourier Transform and semidefinite programming. The structures dramatically reduce the amount of computation and can eliminate the need to store up to five dimensions of parameters while still accurately estimating them.
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Brown, Solly. "The photon model of the quantum electromagnetic field /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16777.pdf.
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Schena, Michael L. "An Electromagnetic Coupling Model for Side-Channel Analysis." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5224.
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This thesis presents an EM coupling model used to enhance power, side-channel measurements used in CPA. The Kalman filter is used to combine measurements of magnetic flux density with voltage or current traditionally used to measure power consumption. The DES encryption algorithm is used to evaluate CPA using EM coupled power measurements compared to traditional power measurements.
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Agutu, Willis Owuor. "Characterization of electromagnetic induction damper." Oxford, Ohio : Miami University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1187267117.
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Lech, James Chrystopher. "Constructing an EMF radiation Hygeia framework and model to demonstrate a public interest override." Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/58695.
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Scientific views on EMF radiation dosimetry and models increasingly suggest that even a tiny increase in the incidence of diseases resulting from exposure to EMF radiation could have broad¹ implications for public health, social accounting and the economy. In South Africa (SA) there is no national EMF radiation exposure protection standard, statutory monitoring or regulations. Multinational High Court deliberations indicate the need for public interest EMF radiation exposure protection standards in South Africa. Domestic citizens, academics, as well as regulatory and legislative practitioners, are unable to effectively monitor and investigate EMF radiation exposure emissions from infrastructure sources, because industries refuse to provide the required data. Industries have, since 2003, continually obstructed access to the data and the establishment of a national EMF radiation standard, citing that it would be in conflict with their strategic economic interests. The demonstration of a public interest override (PIO) function is legislatively required to gain access to the required data. This study constructed (1) a framework and (2) a model to perform test simulations against the (3) PIO criteria to demonstrate a PIO function and tested one PIO simulation scenario. Testing the PIO scenario firstly required the construction of a public interest framework, drawing input from multiple disciplines. The framework literature review used systematic case law and scientific-technical analysis whilst the framework science sought to understand the connections, feedbacks, and trajectories that occur as a result of natural and human system processes and exchanges. The EMF radiation exposure system functions to support human wellbeing needs and to explore the benefits and losses associated with alternative futures with the goal to uncover the current and future limits thereof. In the second instance a HYGEIA² model was selected as a base investigation and forecast simulation tool. The study had to uncover the key attributes and parameters necessary to construct and to run successful EMF radiation exposure simulations. Thereafter the HYGEIA model was modified to specifically identify and evaluate EMF radiation exposure hazard conditions. Through subsequent simulation runs, the constructed framework was then tested. Requested anthroposphere information was synthesized within a systems model to forecast ecosystem services and human-use dynamics under alternative scenarios. The simulation used the model, the model references and the framework for guidelines, thus allowing multiple simulation / demonstration runs for different contexts or scenarios. The third step was the construction of a PIO checklist which guides criteria testing and provides a means of gaining pertinent information for further studies, based on this dissertation. Framework EMF radiation policy inputs into the model were intersected with identified vulnerable area facilities which were selected based on international criteria. The research output revealed potential EMF radiation violations which served as system feedback inputs in support of a demonstrated PIO function. The research recommends that the identified EMF radiation exposure violations of public health undergo a Promotion of Access to Information Act (PAIA) judicial review process to confirm the research findings. The judicial qualification of a PAIA PIO function of ‘substances released into the environment’ and ‘public safety or environmental risk’ would enable access to EMF radiation emissions data essential to future studies.
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Zhao, Lingyin. "Generalized Frequency Plane Model of Integrated Electromagnetic Power Passives." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/27692.
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The challenge to put power electronics on the same cost reduction spiral as integrated signal electronics has yet to be met. In the ongoing work for achieving complete power electronic converter integration, it has proven to be essential to develop a technology for integration of electromagnetic power passives. This integration will enable the incorporation of resonant circuits, transformers, EMI filters and the like into the integrated power electronics modules. These integrated electromagnetic power passives have been realized in terms of distributed structures, utilizing magnetic layers, conductive layers and dielectric layers. Because of the compact structures and the special implementation techniques of these integrated modules, the high frequency parasitic resonance are normally significant and may have negative impact on the performance and EMI characteristics. However, the existing modeling technique can only predict the fundamental resonant frequency and showed neither the causes of the high frequency resonance nor how to calculate those accurately.
In this dissertation, comprehensive research work towards higher order electromagnetic modeling of integrated passive components is presented. Firstly, an L-C cell is identified as the basic building block of integrated passives such as an integrated series resonator. As an essential mistake in the structure evolution process of the original resonant transmission line primitive, the well-known conventional transmission line equivalent circuit as well as the equations are not applicable for the unbalanced current in an integrated passive module. For this particular application, a generalized transmission structure theory that applies to both balanced and unbalanced current has to be developed. The impedances of a generalized transmission structure with various loads and interconnections have been studied. An open-circuited load and a short-circuited load lead to series resonance and parallel resonance, respectively. The equations are substantiated with experimental results. Some preliminary study indicates the advantages of this unbalanced current passives integration technique. Since the existing integrated passive components are no other than some combination of this generalized transmission line primitive, the theoretical analysis may be applied to the further modeling of all integrated passive components.
As the extension of the generalized two-conductor transmission structure model developed for the two-conductor approach, the generalized multi-conductor transmission structure theory has been proposed. As multiple L-C cells are putting in parallel, magnetic and capacitive coupling between cells cannot be neglected. To determine the capacitance between two adjacent conductors on top of the same dielectric substrate, Schwarz-Christoffel transformation and its inverse transformation have been applied with the calculation results verified by measurement. Based on the original voltage and current equations written in matrix form, modal analysis has been conducted to solve the equations. All these provide the basis for any further modeling of an integrated passive structure.
Based on the basic L-C cell structure, this dissertation proposes an alternative multi-cell approach to the integration of reactive components and establishes the principles for its design and operation. It achieves the 3-D integration and has a PCB-mount chip-like structure which may have the potential to be more manufacturable, modularizable and mechanically robust. Different functional equivalents can be obtained by different PCB interconnections. The experimental results confirm the functionality as integrated reactive components for applications such as high frequency resonators.
To apply the multi-conductor generalized transmission structure model to practical integrated passives structures, three typical cases have been studied: spiral-winding structure integrated series resonator, multi-cell structure integrated series resonator and integrated RF EMI filter. All these structures can be treated as one or more multi-conductor transmission structures connected in certain patterns. Different connection patterns only determine the voltage and current boundary conditions with which the equations can be solved. After obtaining the voltages and currents at each point, the impedance or transfer gain of a structure can be obtained. The MATLAB calculation results correlate well with the measurement results. The calculation sensitivities with respect to variation of various parameters are also discussed and causes of resonance at different frequency range are identified.
The proposed generalized transmission structure model based on matrix modal analysis is rather complex and takes a lot of computer time especially when the number of turns is large. Furthermore, the operating frequency of an integrated resonant module is normally around its 1st resonant frequency and up to the 2nd resonant frequency. Therefore, a more simplistic higher order lumped element model which covers the operating range up to the 2nd resonant frequency may be good enough for the general design purpose. A higher order equivalent circuit model for integrated series resonant modules as an example of integrated power passives is presented in this dissertation. Inter-winding capacitance is also considered compared to the conventional 1st order approximation model. This model has been verified by small-signal test results and can be easily implemented into the design algorithm as part of the high frequency design considerations.
The wide band modeling and proposed new structure mentioned above provide a comprehensive basis for better design of integrated passive components. As a general frequency plane modeling approach, the work presented in this dissertation may be extended to other passive structures, such as multi-layer capacitors, planar magnetics, etc..Ph. D.
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Adams, Jacob James. "A coupled electromagnetic-thermal model of heating during radiofrequency ablation." Connect to resource, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1191454972.
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Pimsamarn, Kulapant. "Electromagnetic scattering model for saline ice covered with frost flowers." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/17443.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (leaves 83-87).
by Kulapant Pimsamarn.
M.Eng.
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Danufane, Fadil. "Wireless communications assisted by reconfigurable intelligent surfaces : an electromagnetic model." Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASG038.
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L'émergence de l'environnement radio intelligent (SRE) en tant que nouveau paradigme qui remet en question le status quo dans la communication sans fil a motivé l'utilisation des surface intelligentes reconfigurables (RIS) basées sur des métasurfaces pour améliorer la limite de performance des systèmes de communication sans fil. L'objectif principal de cette thèse est la modélisation d'un système de communication assisté par un RIS à l'aide d'approches basées sur l'électromagnétisme.Le Chapitre 1 présente le concept d'environnement radio intelligent. Nous donnons également la définition du RIS et comment le RIS peut être utilisé dans le contexte du SRE. Nous donnons aussi quelques perspectives historiques et discutons le développement des activités de recherche dans ce contexte.Le Chapitre 2 présente les concepts théoriques nécessaires pour comprendre les résultats des chapitres suivants. Ce chapitre est divisé en deux parties. La première partie traite de la modélisation des métasurfaces où nous passons d'une description microscopique basée sur la physique d'une métasurface et introduisons une représentation macroscopique de celle-ci, qui s'avère appropriée pour une application aux communications sans fil. La deuxième partie présente plusieurs approches analytiques qui nous permettent de calculer le champ électromagnétique dans un certain volume..Le Chapitre 3 fournit une comparaison des performances entre les RISs fonctionnant comme des réflecteurs anormaux et un schéma de relais basé sur le décodage et la transmission. La comparaison est qualitative et couvre une multitude de métriques. En outre, une comparaison quantitative en termes de débits de données réalisables est également présentée. En particulier, les résultats numériques montrent que des RISs suffisamment grands peuvent être plus performants que les systèmes assistés par relais en termes de débit de données, tout en réduisant la complexité.Le Chapitre 4 propose une caractérisation analytique du champ électromagnétique en présence d'un RIS qui est modélisé comme une métasurface homogénéisée et qui fonctionne soit en réflexion ou transmission. Des expressions de forme fermée sont également obtenues dans deux régimes asymptotiques qui sont représentatifs de deux déploiements en champ lointain et en champ proche. Sur la base de l'approche proposée, l'impact de plusieurs paramètres est étudié.Enfin, le Chapitre 5 résume la thèse et discute des perspectives futures qui méritent d'être étudiées pour mieux comprendre les avantages et les inconvénients des RISs pour application aux communications sans filThe emergence of smart radio environment (SRE) as a new paradigm that challenges the status quo in wireless communication has motivated the use of metasurface-based reconfigurable intelligent surface (RIS) to improve the performance limits in wireless communication systems. The main focus of this thesis is the modeling of reconfigurable intelligent surfaces (RIS)-aided communication systems using electromagnetic based methods.Chapter 1 introduces the concept of smart radio environment. We also give the definition of RIS and how RIS can be used in context of SRE. To give some historical perspectives, we also discuss several important milestone papers throughout the development of research activities that lead to the current state of the art.Chapter 2 introduces theoretical concepts that are necessary to understand the results in the subsequent chapters. This chapter is divided into two parts. The first part discusses the metasurfaces modeling where we move from a physics-based microscopic description of a metasurface and introduces a macroscopic representation for it, which is shown to be suitable for application in wireless communications. The second part introduces several analytical approaches that allow us to compute the EM field at any point of a given volume that contains the metasurface.Chapter 3 provides a performance comparison between RISs operating as anomalous reflectors and a decode-and-forward relaying scheme that is representative of competing candidate technologies to realize SREs. The comparison is qualitative and covers multitude metrics. Furthermore, a quantitative comparison in terms of achievable data rates is presented. In particular, the numerical results show that sufficiently large RISs can outperform relay-aided systems in terms of data rate, while reducing the implementation complexity.Chapter 4 proposes an electromagnetic-based analytical characterization of the free-space path-loss of a wireless link in the presence of a RIS that is modeled as a two-dimensional homogenized metasurface made of sub-wavelength scattering elements and that operate either in reflection or transmission mode. The analytical method of physical optics is employed. Closed-form expressions are also obtained in two asymptotic regimes that are representative of far-field and near-field deployments. Based on the proposed approach, the impact of several design parameters and operating regimes is unveiled.Finally, Chapter 5 summarizes the main findings of the thesis and discusses possible future directions that are worth investigating to unlock the full potential of RIS and bring it into practice
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Ribbenfjärd, David. "Electromagnetic transformer modelling including the ferromagnetic core." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-13080.
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In order to design a power transformer it is important to understand its internal electromagnetic behaviour. That can be obtained by measurements on physical transformers, analytical expressions and computer simulations. One benefit with simulations is that the transformer can be studied before it is built physically and that the consequences of changing dimensions and parameters easily can be assessed. In this thesis a time-domain transformer model is presented. The model includes core phenomena as magnetic static hysteresis, eddy current and excess losses. Moreover, the model comprises winding phenomena as eddy currents, capacitive effects and leakage flux. The core and windings are first modelled separately and then connected together in a composite transformer model. This results in a detailed transformer model. One important result of the thesis is the feasibility to simulate dynamic magnetization including the inhomogeneous field distribution due to eddy currents in the magnetic core material. This is achieved by using a Cauer circuit combined with models for static and dynamic magnetization. Thereby, all magnetic loss components in the material can be simulated accurately. This composite dynamic magnetization model is verified through experiments showing very good correspondence with measurements. Furthermore, the composite transformer model is verified through measurements. The model is shown to yield good correspondence with measurements in normal operation and non-normal operations like no-load, inrush current and DC-magnetization.QC20100708
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Albunni, Mohammad Nassar [Verfasser]. "Model Order Reduction of Moving Nonlinear Electromagnetic Devices / Mohammad Nassar Albunni." München : Verlag Dr. Hut, 2011. http://d-nb.info/1010446886/34.
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Roseanu, Toma Sebastien. "Efficient model order reduction method for the analysis of electromagnetic interference." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83928.
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With the advent of high speed interconnects, signal integrity issues resulting from incident electromagnetic fields are becoming a significant challenge for circuit designers. It is necessary therefore to be able to efficiently and accurately simulate interconnect networks affected by this type of interference in order to have a clear picture of how the signal on the interconnect is affected. Since models for interconnect networks affected by incident electromagnetic fields tend to be very large, traditional circuit simulation techniques require a significant CPU cost. In order to address this problem, this thesis introduces a model order reduction technique that allows for the quick frequency domain simulation of large interconnect networks affected by incident electromagnetic fields. Furthermore, a model order reduction algorithm is presented that produces a small, accurate and provably passive macromodel of an interconnect network affected by incident fields, which is very well suited for quick and efficient simulation in both the time and frequency domain. For both cases, projection based model order reduction is used to obtain the desired results. Several examples are provided in order to prove the viability of each proposed new approach.
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Harrison, Robert Anthony. "An electromagnetic field model for the design of RF reed relays." Thesis, University of Plymouth, 2000. http://hdl.handle.net/10026.1/2678.
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A model of the electromechanical characteristics, electrostatic characteristics and coil eddy current losses of a reed relay was developed. These characteristics were returned from reed and coil dimensions. The model was intended as an aid to the design of reed relays for Radio Frequency (RF) and high voltage applications. An electromechanical model of a reed switch and coil was developed using a combination of an axisymmetric finite element model and analytical methods. The characteristics returned from this model were operate, release and differential amp turns, contact gap and contact force. Inclusion of results for contact resistance against contact force yielded the contact resistance characteristics. Electrostatic force between reed contacts was calculated and a criteria for contact arcing in a vacuum applied to allow prediction of breakdown voltage in an evacuated reed switch. The above elements were incorporated in a "Reed Switch Design Program" in which operating, contact resistance and breakdown voltage characteristics were calculated from reed and coil dimensions. Results were found to be in agreement with measured values for three reed switch types. Eddy current losses in relay coils were investigated through experimental measurement of losses occurring in coils mounted around a copper conductor carrying a high frequency current. The losses occurring in the coil were found to present an effective resistance to the current in the conductor. The influence of coil dimensions and the magnetic properties of the conductor on losses were observed. An analytical model of eddy current losses was derived from first principals results and were found concordant with those measured. An "RF Reed Relay Design Program" embodying the eddy current loss model and preceding work was created to demonstrate how relay performance (and efficiency) can be enhanced by tuning reed and coil dimensions. An example of its successful application to product development at Crydom Magnetics Ltd is presented. Proposals for future work are included.
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Maciver, Mark Alasdair. "Electromagnetic characterisation of structures using Krylov subspace model order reduction methods." Thesis, University of Glasgow, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433619.
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Ross, Michael Paul 1963. "Evaluation of a two-dimensional electromagnetic model for hyperthermia treatment planning." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276780.
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A series of hyperthermic, static, torso phantom experiments have been performed. The results are presented in comparison to a two-dimensional, theoretical, electromagnetic model. The 2-D model is assessed for potential use in clinical plannings and evaluations. Included in the assay of this model are comparisons of actual clinical patient data. Theoretically calculated electromagnetic fields and temperatures are obtained using a finite element numerical method (FEM) based on weighted residuals. Two experimental methods of extracting energy deposition data are discussed and utilized: (1) by measuring temperature differentials to calculate specific absorption rates (SAR), and (2) by measuring the square of the E-field directly which relates proportionally to the absorbed power. The employed regional heat source is an annular phased array (APA) operating at 70 MHz. The outcome of the assessment suggests that the results can be quantitative for simple heterogeneous phantom problems, but remain qualitative for clinical evaluative purposes.
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Taylor, Laurence Charles. "A beam tracing model for electromagnetic scattering by atmospheric ice crystals." Thesis, University of Hertfordshire, 2016. http://hdl.handle.net/2299/17645.
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While exact methods, such as DDA or T-matrix, can be applied to particles withsizes comparable to the wavelength, computational demands mean that they are size limited. For particles much larger than the wavelength, the Geometric Optics approximation can be employed, but in doing so wave effects, such as interference and diffraction, are ignored. In between these two size extremes there exists a need for computational techniques which are capable of handling the wide array of ice crystal shapes and sizes that are observed in cirrus clouds. The Beam Tracing model developed within this project meets these criteria. It combines aspects of geometric optics and physical optics. Beam propagation is handled by Snell's law and the law of reflection. A beam is divided into reflected and transmitted components each time a crystal facet is illuminated. If the incident beam illuminates multiple facets it is split, with a new beam being formed for each illuminated facet. The phase-dependent electric field amplitude of the beams is known from their ampli- tude (Jones) matrices. These are modified by transmission and reflection matrices, whose elements are Fresnel amplitude coefficients, each time a beam intersects a crystal facet. Phase tracing is carried out for each beam by considering the path that its 'centre ray' would have taken. The local near-field is then mapped, via a surface integral formulation of a vector Kirchhoff diffraction approximation, to the far-field. Once in the far-field the four elements of the amplitude matrix are trans- formed into the sixteen elements of the scattering matrix via known relations. The model is discussed in depth, with details given on its implementation. The physical basis of the model is given through a discussion of Ray Tracing and how this leads to the notion of Beam Tracing. The beam splitting algorithm is described for convex particles followed by the necessary adaptations for concave and/or ab- sorbing particles. Once geometric aspects have been established details are given as to how physical properties of beams are traced including: amplitude, phase and power. How diffraction is implemented in the model is given along with a review of existing diffraction implementations. Comparisons are given, first against a modified Ray Tracing code to validate the geometric optics aspects of the model. Then, specific examples are given for the cases of transparent, pristine, smooth hexagonal columns of four different sizes and orientations; a highly absorbing, pristine, smooth hexagonal column and a highly absorbing, indented, smooth hexagonal column. Analysis of two-dimensional and one-dimensional intensity distributions and degree of linear polarisation results are given for each case and compared with results acquired through use of the Amster- dam Discrete-Dipole Approximation (ADDA) code; with good agreement observed. To the author's best knowledge, the Beam Tracer developed here is unique in its ability to handle concave particles; particles with complex structures and the man- ner in which beams are divided into sub-beams of quasi-constant intensity when propagating in an absorbing medium. One of the model's potential applications is to create a database of known particle scattering patterns, for use in aiding particle classification from images taken by the Small Ice Detector (SID) in-situ probe. An example of creating such a database for hexagonal columns is given.
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Shen, Chun. "The standard model for relativistic heavy-ion collisions and electromagnetic tomography." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405931790.
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Berg, Matthew James. "A microphysical model of scattering, absorption, and extinction in electromagnetic theory." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1040.
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Cohen, Yuval. "Discrete ARMA model for natural resonances in electromagnetic and acoustic scattering." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA240656.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Morgan, Michael A. Second Reader: Adler, Richard W. "September 1990." Description based on title screen viewed on December 17, 2009. DTIC Descriptor(s): Electromagnetism, target signatures, models, target recognition, waveforms, theses, electromagnetic scattering, finite difference theory, resonant frequency, echoes, resonance, recursive functions, acoustic scattering, transients, verification. DTIC Identifier(s): Radar scattering, sonar scattering, army models, program listings. Author(s) subject terms: Natural resonances; electromagnetic scattering; acoustic scattering; radar target identification; prony's method; ARMA model. Includes bibliographical references (p. 81-82). Also available in print.
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McCalmont, John Francis. "A vector Huygens-Fresnel model of the diffraction of electromagnetic waves." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/298811.
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The scalar Huygens-Fresnel Principle describing the propagation of light is reformulated to take into account the vector nature of light and the associated directed electric and magnetic fields. A vector Huygens secondary source is developed in terms of the fundamental radiating units of electromagnetism: the electric and magnetic dipoles. The vector Huygens wavelets are incorporated into a computer model that calculates the resulting vector fields after light passes through a diffracting system by a wavefront reconstruction process similar to that originally proposed by Huygens himself in 1687. Fresnel and Fraunhofer diffraction patterns are computed for common apertures such as rectangles and circles where theoretical results are available for comparison and validation of the model. However, irregular apertures not easily described in closed mathematical form are studied as well. Both completely absorbing and infinitely conducting screens are considered as well as plane wave and spherical illumination.
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Li, Shaohua. "Development and validation of a microcontroller emissions model." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Li_09007dcc804e2d0e.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 5, 2008) Includes bibliographical references (p. 21-22).
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Alexeev, Arseny. "Quantum rings in electromagnetic fields." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/8021.
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This thesis is devoted to optical properties of Aharonov-Bohm quantum rings in external electromagnetic fields. It contains two problems. The first problem deals with a single-electron Aharonov-Bohm quantum ring pierced by a magnetic flux and subjected to an in-plane (lateral) electric field. We predict magneto-oscillations of the ring electric dipole moment. These oscillations are accompanied by periodic changes in the selection rules for inter-level optical transitions in the ring allowing control of polarization properties of the associated terahertz radiation. The second problem treats a single-mode microcavity with an embedded Aharonov-Bohm quantum ring, which is pierced by a magnetic flux and subjected to a lateral electric field. We show that external electric and magnetic fields provide additional means of control of the emission spectrum of the system. In particular, when the magnetic flux through the quantum ring is equal to a half-integer number of the magnetic flux quantum, a small change in the lateral electric field allows tuning of the energy levels of the quantum ring into resonance with the microcavity mode, providing an efficient way to control the quantum ring-microcavity coupling strength. Emission spectra of the system are calculated for several combinations of the applied magnetic and electric fields.
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Keating, Pierre B. "The inversion of time-domain airborne electromagnetic data using the plate model /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75772.
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Airborne electromagnetic methods were developed in the early 1950's, mostly by Canadian mining exploration companies as a means of economically and successfully searching large areas for conductive massive sulfide mineralisations. As new technologies developed they have become more and more sophisticated. They can detect conductors at depths in excess of 200 m and are routinely used for overburden mapping. The data is digitally recorded and processed. One of the most successful methods is the time domain airborne INPUT$ sp1$ system, for numerous mineral deposits were found by this system in the Canadian Shield.Present interpretation techniques are based on the use of nomograms (i.e. families of pre-computed characteristic responses) and the method is easily amenable to digital processing as it is easy to program and economic to use. For high accuracy interpretation however it is necessary to develop quantitative interpretation techniques that can make full use of all the data available. Inverse theory has been used with great success in all branches of geophysics, but to date in mining exploration it has been used for the interpretation of airborne E.M. data using only the one layer earth model. Use of inverse theory for the plate model has been limited by the high cost of numerically solving the forward problem.
In this thesis we show how to use inverse theory to interpret time domain E.M. data with the rectangular thin plate model by introducing some economies. It is then possible to estimate parameter errors, the correlation matrix and to assess the validity of the model. This is extended to the joint inversion of magnetic and aeromagnetic data a case that often arises in mining problems. It is finally shown that under some assumptions the late time channels can be used to interpret time domain E.M. data in the presence of conductive overburden. ftn$ sp1$Registered trademark of Barringer Research Ltd.
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Wollensak, Gregor, Felix Muchamedjarow, and Richard Funk. "Evaluation of Treatment by Pulsed Electromagnetic Fields in a Rabbit Hyphema Model." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-133633.
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Purpose: Previous clinical studies have suggested a positive effect of low-frequency pulsed electromagnetic fields (PEMF) on wound healing and inflammation in the eye. We tried to test the value of PEMF treatment in a hyphema animal model with well-defined conditions. Methods: After injection of citrated autologous blood for the production of hyphema, 16 rabbit eyes were treated with 10 or 20 mT for 60 min on 4 days within the postoperative week. Two control groups with hyphema alone (n = 8) and PEMF irradiation without hyphema (n = 4) were also included. The rate of resorption was recorded daily. Histopathologic evaluation was performed. Results: The incidence of endothelial cell damage and fibrotic clots was markedly reduced in the 10-mT group while the resorption time of 8 days was identical with the control group. In the 20-mT group, the complication rate and the resorption time was increased versus the control group. Conclusions: The use of PEMF treatment is of some, however, limited value as it did not reduce the resorption time of hyphema but displayed a dose-dependent, beneficial influence on some serious side effects. Future clinical studies with low-dose PEMF irradiation are justified and should determine the optimal dosage and suitable indications of PEMFs as an adjunctive treatment in ocular inflammation or traumaDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Vince, Robert Johnston. "An electromagnetic radome model using an interactive micro-computer finite element algorithm." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/25893.
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Wollensak, Gregor, Felix Muchamedjarow, and Richard Funk. "Evaluation of Treatment by Pulsed Electromagnetic Fields in a Rabbit Hyphema Model." Karger, 2003. https://tud.qucosa.de/id/qucosa%3A27522.
Full textAbstract:
Purpose: Previous clinical studies have suggested a positive effect of low-frequency pulsed electromagnetic fields (PEMF) on wound healing and inflammation in the eye. We tried to test the value of PEMF treatment in a hyphema animal model with well-defined conditions.
Methods: After injection of citrated autologous blood for the production of hyphema, 16 rabbit eyes were treated with 10 or 20 mT for 60 min on 4 days within the postoperative week. Two control groups with hyphema alone (n = 8) and PEMF irradiation without hyphema (n = 4) were also included. The rate of resorption was recorded daily. Histopathologic evaluation was performed.
Results: The incidence of endothelial cell damage and fibrotic clots was markedly reduced in the 10-mT group while the resorption time of 8 days was identical with the control group. In the 20-mT group, the complication rate and the resorption time was increased versus the control group.
Conclusions: The use of PEMF treatment is of some, however, limited value as it did not reduce the resorption time of hyphema but displayed a dose-dependent, beneficial influence on some serious side effects. Future clinical studies with low-dose PEMF irradiation are justified and should determine the optimal dosage and suitable indications of PEMFs as an adjunctive treatment in ocular inflammation or trauma.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Matzner, Shari. "Model-Based Information Extraction From Synthetic Aperture Radar Signals." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/248.
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Synthetic aperture radar (SAR) is a remote sensing technology for imaging areas of the earth's surface. SAR has been successfully used for monitoring characteristics of the natural environment such as land cover type and tree density. With the advent of higher resolution sensors, it is now theoretically possible to extract information about individual structures such as buildings from SAR imagery. This information could be used for disaster response and security-related intelligence. SAR has an advantage over other remote sensing technologies for these applications because SAR data can be collected during the night and in rainy or cloudy conditions. This research presents a model-based method for extracting information about a building -- its height and roof slope -- from a single SAR image. Other methods require multiple images or ancillary data from specialized sensors, making them less practical. The model-based method uses simulation to match a hypothesized building to an observed SAR image. The degree to which a simulation matches the observed data is measured by mutual information. The success of this method depends on the accuracy of the simulation and on the reliability of the mutual information similarity measure. Electromagnetic theory was applied to relate a building's physical characteristics to the features present in a SAR image. This understanding was used to quantify the precision of building information contained in SAR data, and to identify the inputs needed for accurate simulation. A new SAR simulation technique was developed to meet the accuracy and efficiency requirements of model-based information extraction. Mutual information, a concept from information theory, has become a standard for measuring the similarity between medical images. Its performance in the context of matching a simulation image to a SAR image was evaluated in this research, and it was found to perform well under certain conditions. The factors that affect its performance, and the model-based method overall, were found to include the size of the building and its orientation. Further refinements that expand the range of operational conditions for the method would lead to a practical tool for collecting information about buildings using SAR technology. This research was performed using SAR data from MIT-Lincoln Laboratory.
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Ranlöf, Martin. "Electromagnetic Analysis of Hydroelectric Generators." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-146629.
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Hydropower maintains its position as the most important source of renewable electric energy in the world. The efficiency of large hydropower plants is unsurpassed, and after more than hundred years of development, the technology is mature and highly reliable. While new hydro resources are currently being developed in Asia and South America, most European countries go through a phase of intense refurbishment and upgrading of existing plants. Challenges faced by the hydropower industry include a knowledge transfer to new generations and the adaptation of unit designs to meet new operational requirements. As with all branches of engineering, the use of computerized design tools has revolutionized the art of hydropower plant design and the analysis of its performance. In the present work, modern tools like coupled field-circuit models and semi-analytic permeance models are used to address different aspects of electromagnetic analysis of generators in large hydropower plants. The results include the presentation of a mathematical model that uses concepts from rotating field theory to determine the air-gap flux density waveform in a hydroelectric generator. The model was succesfully used to evaluate armature voltage harmonics and damper bar currents at no-load and load conditions. A second study is concerned with the importance of losses due to rotational fields in core loss calculations. It is found that dynamic and rotational effects typically increase the total core loss estimates with about 28% in large hydroelectric generators. In a third study, linear models for the calculation of salient pole shoe form factors at an arbitrary level of magnetic loading are presented. The effect of the damper winding configuration on the damping capability of salient-pole generators is then evaluated in a separate study. The predicted impact of the coupling between damper cages on adjacent poles on the damping torque production is verified in a set of experiments.
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Pirttijärvi, M. (Markku). "Numerical modeling and inversion of geophysical electromagnetic measurements using a thin plate model." Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:951427119X.
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Abstract
The thesis deals with numerical methods designed for the modeling and inversion of geophysical electromagnetic (EM) measurements using a conductive thin plate model. The main objectives are to study the EM induction problem in general and to develop practical interpretation tools for mineral prospecting in particular.
The starting point is a linearized inversion method based on the singular value decomposition and a new adaptive damping method. The inversion method is introduced to the interpretation of time-domain EM (TEM) measurements using a thin plate in free-space. The central part of the thesis is a new approximate modeling method, which is based on an integral equation approach and a special lattice model. At first the modeling method is applied to the interpretation of frequency-domain EM (FEM) data using a thin plate in conductive two-layered earth. After this time-domain responses are modeled applying a Fourier-sine transform of broadband FEM computations.
The results demonstrate that the approximate computational method can model the geophysical frequency and time-domain EM responses of a thin conductor in conductive host medium with sufficient accuracy, and that the inversion method can provide reliable estimates for the model parameters. The fast forward computation enables interactive interpretation of FEM data and feasible forward modeling of TEM responses. The misfit function mapping and analysis of the singular value decomposition have provided additional information about the sensitivity, resolution, and the correlation behavior of the thin plate parameters.
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Pon, Wen-fu. "A model for electromagnetic ring expansion experiment and its application to material characterization /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487946776024132.
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Ao, Wai Kei. "Electromagnetic damping for control of vibration in civil structures." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/31145.
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This thesis investigates an alternative solution to deal with the civil structure vibration. Non-contact electromagnetic or Eddy current damping is selected as a score of vibration suppression. Electromagnetic damping relies on the interaction between a permanent magnet and conductor. An electromagnetic damper (EMD) is applied both to a laboratory footbridge structure and 6-storey model-scale aluminium moment resisting frame (AMRF). In this first study the EMD is connected in series with an electronic shunt circuit to construct an electromagnetic shunt damper (EMSD). A robust optimisation method is applied to develop the corresponding optimal design formula of the EMSD. The principle of an EMSD is to convert mechanical energy to electrical energy. Hence, the induced electromotive force (emf) is generated by electromagnetic induction. This emf induces an amount of shunt damping, which is fedback to the structure to achieve vibration suppression. It was found that when the impedance was applied, the shunt damping feature was of a similar nature to viscous dampers. In contrast, when an RLC (resistance-inductance-capacitance) circuit is connected, the shunt damping is analogous to a tuned mass damper. A second form of EMD is Eddy current damper (ECD), which relies on a geometrical arrangement of permanent magnets and conductors to produce damping forces. The vertical and horizontal orientation of the magnet, unidirectional and alternative pole projection and moving different direction of the conductor are investigated. A theoretical study involving the infinite boundary and finite boundary (the method of images current) is carried out to obtain an analytical calculation of the damping force. On the basis of this analysis, one type of ECD prototype was physically built. A performance test was carried out to determine the damping characteristics of the ECD, which agreed with the results of the numerical analysis. In addition, the ECD was applied to control the dynamics of the 6-storey AMRF. It was found that, the ECD can effectively increase system damping and have a satisfactory control effect.
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Miao, Xincheng. "Numerical study of a continuous casting process with electromagnetic brake." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-144798.
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This dissertation investigates the effect of electromagnetic braking and gas injection on the fluid flow in a continuous casting slab mold numerically and makes verifications on basis of a small Liquid Metal Model for Continuous Casting of steel (mini-LIMMCAST). Numerical calculations were performed by means of the software package CFX with an implemented RANS-SST turbulence model. The non-isotropic nature of the MHD turbulence was taken into account by specific modifications of the turbulence model. The numerical results were validated by flow measurements at the mini-LIMMCAST facility. Numerical simulations disclose the damping effect on the flow closely depending on the wall conductance ratio. In addition, specific modifications of the turbulence model play a crucial role in reconstructing the peculiar phenomenon of an excitation of nonsteady, nonisotropic, large-scale flow perturbations caused by the application of the DC magnetic field.
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Gustafsson, Stefan. "Electromagnetic dispersion modeling and analysis for HVDC power cables." Licentiate thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-32525.
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Derivation of an electromagnetic model, regarding the wave propagation in a very long (10 km or more) High Voltage Direct Current (HVDC) power cable, is the central part of this thesis. With an existing “perfect” electromagnetic model there are potentially a wide range of applications.The electromagnetic model is focused on frequencies between 0 and 100 kHz since higher frequencies essentially will be attenuated. An exact dispersion relation is formulated and the propagation constant is computed numerically. The dominating mode is the first Transversal Magnetic (TM) mode of order zero, denoted TM01, which is also referred to as the quasi-TEM mode. A comparison is made with the second propagating TM mode of order zero denoted TM02. The electromagnetic model is verified against real time data from Time Domain Reflection (TDR) measurements on a HVDC power cable. A mismatch calibration procedure is performed due to matching difficulties between the TDR measurement equipment and the power cable regarding the single-mode transmission line model.An example of power cable length measurements is addressed, which reveals that with a “perfect” model the length of an 80 km long power cable could be estimated to an accuracy of a few centimeters. With the present model the accuracy can be estimated to approximately 100 m.In order to understand the low-frequency wave propagation characteristics, an exact asymptotic analysis is performed. It is shown that the behavior of the propagation constant is governed by a square root of the complex frequency in the lowfrequency domain. This thesis also focuses on an analysis regarding the sensitivity of the propagation constant with respect to some of the electric parameters in the model. Variables of interest when performing the parameter sensitivity study are the real relative permittivityand the conductivity.
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Fan, Taian. "Zero-Group-Velocity Propagation Of Electromagnetic Wave Through Nanomaterial." ScholarWorks @ UVM, 2016. https://scholarworks.uvm.edu/graddis/549.
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This research will investigate the problem on the propagation of electromagnetic wave through a specific nanomaterial. The nanomaterial analyzed is a material consisting of a field of Pt nanorods. This field of Pt nanorods are deposited on a substrate which consists of a RuO2 nano structure. When the nanorod is exposed to an electron beam emitted by a TEM (Transmission electron microscopy). A wave disturbance has been observed. A video taken within the chamber shows a wave with a speed in the scale of um/s (Á?10Á?^(-6) m/s), which is 14 orders of magnitude lower than speed of light in free space (approximate 3ÁÁ?10Á?^8 m/s ). A physical and mathematical model is developed to explain this phenomenon. Due to the process of fabrication, the geometry of the decorated Pt nanorod field is assumed to be approximately periodic. The nanomaterials possess properties similar to a photonic crystal. Pt, as a noble metal, shows dispersive behaviours that is different from those ones of a perfect or good conductors. A FDTD algorithm is implemented to calculate the band diagram of the nanomaterials. To explore the dispersive properties of the Pt nanorod field, the FDTD algorithm is corrected with a Drude Model. The analysis of the corrected band diagram illustrates that the group velocity of the wave packet propagating through the nanomaterial can be positive, negative or zero. The possible zero-group velocity is therefore used to explain the extremely low velocity of wave (wave envelope) detected in the TEM.
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Vojisavljevic, Vuk, and Vuk Vojisavljevic@rmit edu au. "The Electromagnetic Field as a Modulator of a Protein Activity, and the Resonant Recognition Model." RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080530.162332.
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In this study, it was experimentally proved, for the first time, that it is possible to predict the frequency of electromagnetic radiation that can modulate activity of proteins and more specifically activity of enzymes. The prediction was obtained using the computational model so called the Resonant Recognition Model (RRM). The model was tested here experimentally using the reaction catalysed with the enzyme l-lactate dehydrogenase (LDH). The RRM model was applied to the group of the enzymes belonging to the sub-subclass EC 1.1.1.27 i.e. l-lactate dehydrogenase. The wavelengths of the electro magnetic radiation calculated by the RRM and proposed to alternate activity of l-lactate dehydrogenate were identified at =620 25 nm and =840 25 nm. Enzyme activity was then measured after the exposure to the low-intensity, electromagnetic radiation (EMR) within the proposed EMR range [560-860 nm]. The experimental results have indeed shown that there is a significant increase in the activity of LDH only after irradiation within the range of the frequencies predicted by the RRM: 596nm (12%; P less than 0.001) and 829 nm (11.8%, P less than 0.001). These results prove successfully that activity of proteins and more specifically enzymes could be modified by EMR radiation of specific frequencies and even more that RRM computational model can successfully predict these frequencies.
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Yang, Kang. "Numerical and semi analytical models for electromagnetic ring expansion test." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2350.
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Le taux de déformation des matériaux est élevé pendant le soudage / formage à grande vitesse, le découpage, le sertissage, etc. Les propriétés des matériaux sous déformation à grande vitesse ne suivent pas la même loi que dans le cas de chargement quasi statiques. La caractérisation des matériaux à taux de déformation important est assez difficile et nécessite des équipements sophistiqués. Grâce au développement de la technologie de formage électromagnétique, le test d'expansion d'anneau électromagnétique présente un grand potentiel à utiliser pour caractériser les matériaux à haute vitesse de déformation. Pendant le test d’expansion de l’anneau électromagnétique, la pièce à usiner peut atteindre une vitesse d’expansion de l’ordre de 100m/s et une vitesse de déformation de 104 s-1. Par conséquent, ce test peut être utilisé pour prédire les paramètres du matériau, tels que la dureté et la ductilité à déformation à grande vitesse. Pour d’atteindre cet objectif, un modèle approprié décrivant le processus est nécessaire. Ce modèle doit contenir un couplage électromagnétique-mécanique-thermique pour bien décrire le problème multi-physique. Il existe deux méthodes principales de modélisation dans la littérature, viz. Les méthodes semi-analytiques et les méthodes des éléments finis (parfois combinées avec la méthode des éléments limitants). Les méthodes semi-analytiques nécessitent un temps de calcul court mais offrent une faible précision par rapport aux méthodes des éléments finis. Cependant, en raison de la complexité du couplage multi-physique, l’erreur de calcul est difficile à estimer. De plus, les déformations hétérogènes ainsi que les états de contrainte compliqués peuvent influencer l’identification. Dans ce sens, cette thèse s’est principalement concentrée sur les méthodes d’analyse et de modélisation du test d’expansion d’anneau électromagnétique, incluant les comportements locaux et les phénomènes dynamiques à l’aide des outils expérimentaux et numériques. Par ailleurs, cette thèse comprend aussi le développement d’un méthode semi-analytique permettant le couplage multi-physique, ce qui a été validé par un modèle numérique idéal et par des tests expérimentaux. Les résultats expérimentaux ont été obtenus à l’aide d’une caméra à grande vitesse et du vélocimétrie photovoltaïque Doppler (PDV) pour différents cas tests. Ils ont été utilisés pour déterminer les paramètres du processus et du matériau à l’aide des modèles numériques. Les modèles adaptés pour analyser les états de contrainte et de déformation durant le test d’expansion d’anneau montrent que ce dernier n’est pas un test de traction uniaxial pur comme revendiqué par les chercheurs. En outre, le phénomène de vibration qui se produise de la récupération élastique a été étudié par simulations multi-physiques et par systèmes PDV. Cette étude de récupération élastique permet de mieux comprendre les paramètres influençant du test, ce qui pourrait être utilisé pour contrôler le rebond dans d’autres processus électromagnétique. La méthode de modélisation semi-analytique pour le test d’expansion de l’anneau électromagnétique, qui comprend quatre parties de calcul (partie mécanique, thermique, force de Lorentz et courant de Foucault), a été analysée à l’aide de simulations numériques. Les résultats obtenus ressemblent étroitement aux résultats obtenus par un test idéal et un test expérimental. L’analyse d’erreur des différents aspects physiques permet d’améliorer la précision de calcul semi-analytique, ce qui pourrait être utilisé comme outil supplémentaire d’obtention rapide des paramètres de contrôle dans les tests. Il pourrait aussi être utilisé pour l’identification des paramètres des matériels à déformation à grande vitesseHigh stain rate material deformations are prevalent during high speed impacts, high speed forming/welding, cutting, crimping, blast etc. Characteristics of materials under high strain rate deformation do not follow the same as it occurs under the quasi-static loading conditions. However, characterization of materials under high strain rate deformation is always challenging and it requires sophisticated equipment. Thanks to the development in electromagnetic forming technology, the electromagnetic ring expansion test shows a great potential to be used to characterize materials under high strain rate conditions. During the electromagnetic ring expansion test, the workpiece can reach deformation velocities in the order of 100 m/s and a strain rate of up to 104 s-1. Consequently, this test can be used to predict the material parameters such as the strain rate hardening and ductility under extremely high strain rates (strain rates in the order of 103 – 104 s-1). In order to achieve this goal, an appropriate model is required to describe the process. The model should contain an electromagnetic-mechanical-thermal coupling to obtain the accurate multi-physics nature of the problem. There exist two main modeling methods in literature, viz., the semi-analytical methods and finite element methods (sometime combined with boundary element method). Normally, the semi-analytical methods require short calculation time while it provides lower accuracy in comparison with finite element methods. However, due to the complexity of multi-physics coupling, the calculation error is difficult to be analyzed. Moreover, errors in calculation and identification assumptions may also result from heterogeneous deformations or localized specific phenomena (such as local necking at multi points or electric current localization, skin effect, edge effect of Lorentz force etc.) that could influence identification work as well as stress and strain states. Therefore, this thesis mainly focused on the analysis and modeling methods of ring expansion test including local behaviors and dynamic phenomena with the help of experimental and numerical tools. Moreover, this thesis also includes a development of a semi-analytical method with multi-physics coupling capabilities, which has been validated using a theoretical model and experimental frameworks. Experimental measurements were obtained using high-speed cameras and photonic Doppler velocimetry (PDV) for various test cases are used together with numerical models to investigate the process and material parameters. The models used to analyze the stress and stain states during a ring expansion test show that the ring expansion test is not a pure uniaxial tensile test as claimed by researchers. Besides, another potential process behavior, the vibration phenomena that occurs during the elastic recovery was investigated using multi-physics simulations and PDV systems. This investigation of the elastic recovery helps to understand the potential influencing parameters of the test those are applicable and could be used to control the springback phenomenon during other electromagnetic forming processes. The semi-analytical modeling method for ring expansion test including four calculation parts (mechanical part, eddy current, Lorentz force calculation, thermal part) were analyzed with the help of numerical simulations. The results obtained from analytical work closely resemble with the numerical simulations for both theoretical model and an experimental case study. The error analysis of various physical aspects allows improving the accuracy of semi-analytical calculation that could be used as an additional platform to obtain rapid calculation of the test conditions. This semi-analytical method could be extended in the future to identify material parameters under high strain rate deformations
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Santhanam, Ramya. "LOCALIZED WOUND HEALING: A MATHEMATICAL MODEL FOR ELECTROMAGNETIC INDUCTION ON COATED NANOFIBER WOUND DRESSINGS." Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1147883471.
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Thesis (M.S.)--University of Akron, Dept. of Biomedical Engineering, 2006."May, 2006." Title from electronic thesis title page (viewed 12/03/2007) Advisor, S.I. Hariharan; Committee members, Daniel B. Sheffer, Narender P. Reddy; Department Chair, Daniel B. Sheffer; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Wang, Li-Fang Ph D. Massachusetts Institute of Technology. "Monte Carlo simulation model for electromagnetic scattering from vegetation and inversion of vegetation parameters." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38923.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 171-185).
In this thesis research, a coherent scattering model for microwave remote sensing of vegetation canopy is developed on the basis of Monte Carlo simulations. An accurate model of vegetation structure is essential for the calculation of scattering from vegetations, especially those with closely spaced elements in clusters. The Monte Carlo approach has an advantage over the conventional wave theory in dealing with complex vegetation structures because it is not necessary to find the probability density functions and the pair-distribution functions required in the analytic formulation and usually difficult to obtain for natural vegetation. To achieve a realistic description of the vegetation structure under consideration, two methods may be employed. One method requires the specification of the number of each type of component and the relative orientations of the components. In a structural model which incorporates this method, the detailed features can be preserved to the desired level of accuracy. This structural model is applied to two types of vegetation- --rice crops and sunflowers.
(cont.) The developed structural model for rice crops takes into account the coherent wave interactions made prominent by the clustered and closely spaced structure of rice crops, and is validated with the ERS-1 and RADARSAT data. It is utilized to interpret the experimental observations from the JERS-1 data, such as the effects of the structure of rice fields, and to predict the temporal response of rice growth. The structural model developed for sunflowers is validated using the airborne Remote Sensing Campaign Mac-Europe 91 multi-frequency and multi-polarization data acquired for sunflower fields at the Montespertoli test site in Italy. Another method to characterize vegetation structure uses growth rules. This is especially useful in modeling trees, which are structurally more complex. The Lindenmayer systems (L-systems) are utilized to fully capture the architecture of trees and describe their growth. Monte Carlo simulation results of the scattering returns from trees with different structures and at different growth stages are calculated and analyzed. The concept of the "structure factor" which extracts the structural information of a tree and and provides a measure of the spatial distribution of branches is defined, and computed for trees with different architectures.
(cont.) After study of the forward scattering problem in which the scattering coefficients are determined on the basis of known physical characteristics of the scattering objects or medium, the inverse scattering problem is considered in which the characteristics of the scattering objects or medium are to be calculated from the scattering data. In this thesis research, neural networks are applied to the inversion of geophysical parameters including soil moisture and surface parameters, sunflower biomass, as well as forest age (or equivalently, forest biomass). They are found to be especially useful for multi-dimensional inputs such as multi-frequency polarimetric scattering data. For the inversion of soil moisture and surface parameters, neural networks are trained with theoretical surface scattering models. To retrieve the sunflower biomass, neural networks are trained with the scattering returns obtained from the developed vegetation scattering model based on the Monte Carlo approach. To assess the performance of the use of experimental data to train the neural networks, the polarimetric radar data acquired by the Spaceborne Imaging Radar-C (SIR-C) over the Landes Forest in France are utilized as the training data to retrieve the forest age. Different combinations of backscattering data are used as input to the neural net in order to determine the combination which yields the best inversion result.
by L-i-Fang Wang.
Ph.D.
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Christensen, Nikolaj Kruse, Ty Paul A. Ferre, Gianluca Fiandaca, and Steen Christensen. "Voxel inversion of airborne electromagnetic data for improved groundwater model construction and prediction accuracy." COPERNICUS GESELLSCHAFT MBH, 2017. http://hdl.handle.net/10150/623198.
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We present a workflow for efficient construction and calibration of large-scale groundwater models that includes the integration of airborne electromagnetic (AEM) data and hydrological data. In the first step, the AEM data are inverted to form a 3-D geophysical model. In the second step, the 3-D geophysical model is translated, using a spatially dependent petrophysical relationship, to form a 3-D hydraulic conductivity distribution. The geophysical models and the hydrological data are used to estimate spatially distributed petrophysical shape factors. The shape factors primarily work as translators between resistivity and hydraulic conductivity, but they can also compensate for structural defects in the geophysical model. The method is demonstrated for a synthetic case study with sharp transitions among various types of deposits. Besides demonstrating the methodology, we demonstrate the importance of using geophysical regularization constraints that conform well to the depositional environment. This is done by inverting the AEM data using either smoothness (smooth) constraints or minimum gradient support (sharp) constraints, where the use of sharp constraints conforms best to the environment. The dependency on AEM data quality is also tested by inverting the geophysical model using data corrupted with four different levels of background noise. Subsequently, the geophysical models are used to construct competing groundwater models for which the shape factors are calibrated. The performance of each groundwater model is tested with respect to four types of prediction that are beyond the calibration base: a pumping well's recharge area and groundwater age, respectively, are predicted by applying the same stress as for the hydrologic model calibration; and head and stream discharge are predicted for a different stress situation.
As expected, in this case the predictive capability of a groundwater model is better when it is based on a sharp geophysical model instead of a smoothness constraint. This is true for predictions of recharge area, head change, and stream discharge, while we find no improvement for prediction of groundwater age. Furthermore, we show that the model prediction accuracy improves with AEM data quality for predictions of recharge area, head change, and stream discharge, while there appears to be no accuracy improvement for the prediction of groundwater age.
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De, Leo Alfredo. "Rescue of buried people: an electromagnetic model for a feasibility study and system design." Doctoral thesis, Università Politecnica delle Marche, 2014. http://hdl.handle.net/11566/242864.
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Lo scopo di questo lavoro è di evidenziare la fondamentale importanza di un modello elettromagnetico per la progettazione di un sistema elettromagnetico per la ricerca di esseri umani sepolti sotto macerie in caso di eventi disastrosi come terremoti, frane o valanghe.
Il sistema proposto si basa sul riconoscimento del movimento della vittima causato dalla sua attività respiratoria, rilevandone in particolare la frequenza: infatti, quando un'onda elettromagnetica incide su un corpo umano che varia le sue dimensioni durante un atto respiratorio, l'onda riflessa varia di conseguenza alcune sue proprietà elettromagnetiche come l’ampiezza, la frequenza, la fase o il tempo di ritardo in caso siano usati impulsi.
La geometria dello scenario e del corpo è stata semplificata per risolvere in una forma chiusa il problema elettromagnetico dell'interazione del corpo e campo interferente.
Nonostante la semplice formulazione, i risultati sono soddisfacenti e mostrano come alcuni importanti requisiti di sistema possano essere ottenuti a priori, come ad esempio l’intervallo ottimale di frequenze di lavoro o la scelta tra la modalità di funzionamento a onda continua e quella basata su impulsi a banda larga. Il modello è inoltre in grado di predire la sensibilità in termini di fase e modulo variazioni in funzione dello scenario previsto.
Nella sua prima formulazione, il modello è basato su illuminazione da onde piane del solo torace umano, e in seguito sono state introdotte le altre parti del corpo: questo modello è stato validato mediante simulazione numerica.
In seguito, al fine di considerare uno scenario più realistico, l'illuminazione onda piana è stata sostituita con la radiazione da un’antenna ad apertura equivalente, e le predizioni del modello sono state confermate dai risultati delle misure sperimentali. Il modello è stato quindi validato sia numericamente sia sperimentalmente.
Grazie alle specifiche a priori fornite dal modello analitico, è stato costruito con attrezzature di laboratorio un prototipo di un sistema elettromagnetico per rilevare la frequenza respiratoria, e tale sistema è stato testato con successo in ambiente controllato. In fine i test sono stati ripetuti in una simulazione di una vittima sepolta da terreno di scavo durante la realizzazione di una galleria in un cantiere stradale.
Queste misure hanno dimostrato la validità del modello elettromagnetico proposto e la fattibilità di un sistema elettromagnetico per la ricerca di una vittima sepolta da macerie e la sua capacità di rilevare l'attività respiratoria.The aim of this work is to highlight the paramount importance of the availability of an electromagnetic model for the design of a system based on electromagnetic radiation for search and rescue operation of humans buried under different materials as debris, rubbers and snow slide. In this thesis the monitoring of the breathing activity, in particular the respiration frequency, of a man buried into a homogeneous lossy medium has been analyzed. The proposed system is based on the recognition of the movement of the victim due to its respiratory activity: in particular, when an electromagnetic wave impinges a human body that varies its dimension during a respiratory act, the reflected wave varies its properties as amplitude, frequency, phase or delay time is pulses are used. The geometries of the scenario and the body have been simplified in order to model the electromagnetic problem of the interaction of the body and impinging field in a closed-form. In spite of the simple formulation the results are satisfactory and show how some a priori important system requirements can be obtained, as for example the most suitable working frequency range and the choice between continuous wave and ultra-wide band pulse based system. The model is able to predict the sensitiveness in terms of phase and module variations depending on the scenario. At first the model is based on plane wave illumination of a human thorax, and then the whole body is introduced: this model was validated by numerical simulation. Afterwards in order to get a more realistic scenario the plane wave illumination was replaced with a realistic transmitting/receiving element, modeled as an equivalent aperture antenna, and the model prediction was confirmed by experimental results. The model was validated both numerically and experimentally. Thanks to the analytical model prediction, a prototype of an electromagnetic system to detect the breathing frequency was built up with laboratory equipment, and used both in laboratory and in a realistic scenario: These measurements showed the feasibility of an electromagnetic victim rescue system, and its ability to detect the respiratory activity during a simulation of a victim in a real scenario, where a victim was buried by excavated soil in a road construction site, were experimentally verified.
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Niamsuwan, Noppasin. "Electromagnetic Scattering Models for the Global Ice Sheet Mapping Orbiter Demonstrator." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1259701421.
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Wijesundara, Shanka N. "Studies of Electromagnetic Backscattering from Ocean Surfaces." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565976614784442.
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Terizhandur, Varadharajan Narayanan. "Fast methods for full-wave electromagnetic simulations of integrated circuit package modules." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41059.
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Fast methods for the electromagnetic simulation of integrated circuit (IC) package modules through model order reduction are demonstrated. The 3D integration of multiple functional IC chip/package modules on a single platform gives rise to geometrically complex structures with strong electromagnetic phenomena. This motivates our work on a fast full-wave solution for the analysis of such modules, thus contributing to the reduction in design cycle time without loss of accuracy. Traditionally, fast design approaches consider only approximate electromagnetic effects, giving rise to lumped-circuit models, and therefore may fail to accurately capture the signal integrity, power integrity, and electromagnetic interference effects.
As part of this research, a second order frequency domain full-wave susceptance element equivalent circuit (SEEC) model will be extracted from a given structural layout. The model so obtained is suitably reduced using model order reduction techniques. As part of this effort, algorithms are developed to produce stable and passive reduced models of the original system, enabling fast frequency sweep analysis. Two distinct projection-based second order model reduction approaches will be considered: 1) matching moments, and 2) matching Laguerre coefficients, of the original system's transfer function. Further, the selection of multiple frequency shifts in these schemes to produce a globally representative model is also studied. Use of a second level preconditioned Krylov subspace process allows for a memory-efficient way to address large size problems.
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Bard, Deborah. "Search for the inclusive b->d gamma decay at BaBar." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/1556.
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Radiative penguin decays of B mesons are favour-changing neutral current (FCNC) processes, studies of which provide fertile ground for precision tests of the Standard Model. Because such decays must proceed through 1-loop or higher order processes, they are rare and their amplitudes are particularly sensitive to interference from other FCNC interactions beyond the SM. This thesis presents the search for the rare radiative penguin process b -> d gamma, carried out at the BABAR experiment.
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Osaretin, Idahosa Andrew. "Theoretical Model and Electromagnetic Wave Propagation Characteristics for the Magnetoelectric Effect in Layered Piezoelectric and Piezomagnetic Composites." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1297272494.
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Hagen, Jürgen von [Verfasser]. "Wide band electromagnetic coupling to a cavity : an integral representation based model. / Jürgen v. Hagen." Karlsruhe : KIT-Bibliothek, 1997. http://d-nb.info/1013929454/34.
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Willers, Bernard. "Pion electromagnetic form factor in the Kroll-Lee-Zumino model at zero and finite temperature." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/6510.
Full textAbstract:
Includes abstract.Includes bibliographical references (p. 47-48).
The renormalizable Abelian quantum field theory model of Kroll, Lee and Zumino is used to calculate next-to-leading order corrections to the pion electromagnetic form factor in vector meson dominance. At zero temperature the predictions for both the form factor and electromagnetic radius are found to improve greatly over the tree level result, and are in good agreement with the experimental data. A calculation of the vertex and self energy functions in the Matsubara formalism at finite temperature do not agree with the results of the Gale & Kapusta calculations. The resulting prediction for the radius is found to increase with temperature, consistent vith ideas about haclronic deconfinernent.
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Scher, Aaron D. "Boundary effects in the electromagnetic response of a metamaterial using the point-dipole interaction model." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337150.
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