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1
Chakrabarti, Abhimanyu. "Transmission line matrix modelling for semiconductor transport." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338228.
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Ahmadian, Mansour. "Transmission Line Matrix (TLM) modelling of medical ultrasound." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/427.
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This thesis introduces TLM as a new method for modelling medical ultrasound wave propagation. Basic TLM theory is presented and how TLM is related to Huygens principle is discussed. Two dimensional TLM modelling is explained in detail and one dimensional and three dimensional TLM modelling are explained. Implementing TLM in single CPU computers and parallel computers is discussed and several algorithms are presented together with their advantages and disadvantages. Inverse TLM and modelling non linear wave propagation and different types of mesh are discussed. A new idea for modelling TLM as a digital filter is presented and removing the boundary effect based on digital filter modelling of TLM is discussed. Some modelling experiments such as : 1) Focusing mirror, 2) Circular mirror, 3) Array transducers, 4) Doppler effect, are presented and how to use TLM to model these experiments is explained. A new low sampling rate theory for TLM modelling is proposed and verified. This new theory makes the modelling of a much larger spaces practical on a given hardware platform.
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Willison, Peter A. "Transmission line matrix modelling of underwater acoustic propagation." Thesis, University of Essex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334426.
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Melton, Mark David. "Precise surface placement in transmission line matrix modelling." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/14898.
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The Transmission Line Matrix modelling technique is a spatially discrete, time domain numerical modelling method. It has uses in many fields; however its main applications are for acoustic and electromagnetic modelling. This work focuses upon the study the positioning of surfaces which reflect and scatter waves within TLM models. In particular, the way in which the precise position of objects and surfaces are represented within the limitations of the model. Previously reported methods for improving surface positioning are investigated and evaluated. The previous methods are used as the basis for a new and improved method. The key features and performance of the method are appraised and areas for improvement defined. From this starting point, an enhanced method modifying the basic features and implementation is described. This enhanced method gives significantly improved results. Extensive testing of the original method and the enhanced method . are given in an unobstructed abstract case, clearly showing the performance differences of both methods and suitability for representing preCisely placed surfaces. Examples of the application of the method for both electromagnetic and acoustic modelling are given. Applications to ideal, abstract, and real world models are included. Results are compared with standard analytical benchmarks, results from other methods and measured data. The results show that there is a very clear and significant improvement in the performance of the TLM technique if the precise placement scheme given here is used.
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Rebel, Jürgen N. "On the foundations of the transmission line matrix method." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=959770089.
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Chen, Zhizhang. "The transmission line matrix (TLM) method and its boundary treatments." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/10888.
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The Transmission Line Matrix (TLM) numerical algorithm, based on the discrete Huygens' principle, has been extensively used to solve electromagnetic structure problems. The major advantage of this method is its simplicity and flexibility as the vectorial Maxwell's Equations are transformed into a simple numerical model of digital signal processing system. In this thesis, new and efficient numerical modeling concepts and procedures have been developed for the analysis of electromagnetic structures with the TLM method: (1) With the introduction of the equivalent field quantities defined between nodes, the TLM Method has been shown to be exactly equivalent to a finite-difference timedomain (FD-TD) formulation. Therefore, the numerical foundation of the TLM approach has been fully demonstrated and the basis for mathematically understanding the TLM method has been provided. As a result, the conventional TLM boundary conditions has been verified theoretically, and hence a systematic way for constructing the TLM boundary conditions has been developed. In addition, a new boundary description for the TLM method has been proposed, which renders TLM method more flexibility in its boundary treatments. (2) Based on the equivalence between the TLM method and the FD-TD method, an absorbing and a connecting boundary formulations have been developed for TLM simulations. With these formulations, the TLM method can be applied for solving more realistic scattering and radiation problems with open structures. The computation examples given in this thesis are with the structures of waveguides, two-dimensional and three-dimensional obstacles illuminated by plane waves. The numerical results show good agreement with those obtained with the Method of Moment, and thus validate the boundary conditions developed. (3) By using the discrete Fourier Transform, a new algorithm has been developed for interfacing the TLM method with the frequency-domain solutions. The technique employ the prior knowledge of frequency-domain solutions at boundaries and combine them with TLM simulations, leading to considerable decrease in memory and CPU time. It also allows the TLM method to be used with highly conductive materials for solving shielding problems. The good results were obtained with significant reduction of the computation expenditure.
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Stubbs, David Michael. "Modelling distributed amplifier structures using the transmission line matrix (TLM) method." Thesis, University of Hull, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395515.
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Kang, Ning. "ADVANCEMENTS IN TRANSMISSION LINE FAULT LOCATION." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/69.
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In modern power transmission systems, the double-circuit line structure is increasingly adopted. However, due to the mutual coupling between the parallel lines it is quite challenging to design accurate fault location algorithms. Moreover, the widely used series compensator and its protective device introduce harmonics and non-linearities to the transmission lines, which make fault location more difficult. To tackle these problems, this dissertation is committed to developing advanced fault location methods for double-circuit and series-compensated transmission lines.
Algorithms utilizing sparse measurements for pinpointing the location of short-circuit faults on double-circuit lines are proposed. By decomposing the original network into three sequence networks, the bus impedance matrix for each network with the addition of the fictitious fault bus can be formulated. It is a function of the unknown fault location. With the augmented bus impedance matrices the sequence voltage change during the fault at any bus can be expressed in terms of the corresponding sequence fault current and the transfer impedance between the fault bus and the measured bus. Resorting to VCR the superimposed sequence current at any branch can be expressed with respect to the pertaining sequence fault current and transfer impedance terms. Obeying boundary conditions of different fault types, four different classes of fault location algorithms utilizing either voltage phasors, or phase voltage magnitudes, or current phasors, or phase current magnitudes are derived. The distinguishing charactristic of the proposed method is that the data measurements need not stem from the faulted section itself. Quite satisfactory results have been obtained using EMTP simulation studies.
A fault location algorithm for series-compensated transmission lines that employs two-terminal unsynchronized voltage and current measurements has been implemented. For the distinct cases that the fault occurs either on the left or on the right side of the series compensator, two subroutines are developed. In additon, the procedure to identify the correct fault location estimate is described in this work. Simulation studies carried out with Matlab SimPowerSystems show that the fault location results are very accurate.
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Jaques, Stuart Roland. "A TLM analysis of an all-optical switching device." Thesis, University of Hull, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363266.
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Tadanki, Sasidhar. "Multiple resonant multiconductor transmission line resonator design using circulant block matrix algebra." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/249.
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The purpose of this dissertation is to provide a theoretical model to design RF coils using multiconductor transmission line (MTL) structures for MRI applications. In this research, an MTL structure is represented as a multiport network using its port admittance matrix. Resonant conditions and closed-form solutions for different port resonant modes are calculated by solving the eigenvalue problem of port admittance matrix using block matrix algebra. A mathematical proof to show that the solution of the characteristic equation of the port admittance matrix is equivalent to solving the source side input impedance is presented. The proof is derived by writing the transmission chain parameter matrix of an MTL structure, and mathematically manipulating the chain parameter matrix to produce a solution to the characteristic equation of the port admittance matrix. A port admittance matrix can be formulated to take one of the forms depending on the type of MTL structure: a circulant matrix, or a circulant block matrix (CB), or a block circulant circulant block matrix (BCCB). A circulant matrix can be diagonalized by a simple Fourier matrix, and a BCCB matrix can be diagonalized by using matrices formed from Kronecker products of Fourier matrices. For a CB matrix, instead of diagonalizing to compute the eigenvalues, a powerful technique called “reduced dimension method� can be used. In the reduced dimension method, the eigenvalues of a circulant block matrix are computed as a set of the eigenvalues of matrices of reduced dimension. The required reduced dimension matrices are created using a combination of the polynomial representor of a circulant matrix and a permutation matrix. A detailed mathematical formulation of the reduced dimension method is presented in this thesis. With the application of the reduced dimension method for a 2n+1 MTL structure, the computation of eigenvalues for a 4n X 4n port admittance matrix is simplified to the computation of eigenvalues of 2n matrices of size 2 X 2. In addition to reduced computations, the model also facilitates analytical formulations for coil resonant conditions. To demonstrate the effectiveness of the proposed methods (2n port model and reduced dimension method), a two-step approach was adopted. First, a standard published RF coil was analyzed using the proposed models. The obtained resonant conditions are then compared with the published values and are verified by full-wave numerical simulations. Second, two new dual tuned coils, a surface coil design using the 2n port model, and a volume coil design using the reduced dimensions method are proposed, constructed, and bench tested. Their validation was carried out by employing 3D EM simulations as well as undertaking MR imaging on clinical scanners. Imaging experiments were conducted on phantoms, and the investigations indicate that the RF coils achieve good performance characteristics and a high signal-to-noise ratio in the regions of interest.
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Austin, John Dawson. "General curvilinear orthogonal meshes for use in TLM diffusion applications." Thesis, University of Hull, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335178.
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De, Menezes Leonardo Rodrigues Araujo Xavier. "Modeling of general medium constitutive relationships in the transmission line matrix method (TLM)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21929.pdf.
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Koay, Adeline Lay Kuen. "Transmission line matrix (TLM) based thermal management and control of spatially distributed systems." Thesis, University of Hull, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417159.
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Hindmarsh, Dorian. "Modelling of the automotive pass-by noise test using transmission line matrix techniques." Thesis, University of East Anglia, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405254.
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Stothard, David. "The development of an application specific processor for the transmission line matrix method." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/14899.
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This thesis details the development of an application specific processor for the transmission line matrix (TLM) method. The application of TLM to the modelling of wave propagation in two and three dimensions is introduced with the discussion focusing on the concept of computational efficiency. Methods for improving computational efficiency are reviewed, in particular the implementation of TLM on large scale parallel computers. It is shown that these methods, while increasing throughput, make inefficient use of available resources. The review of existing methods is used to define a set of goals for a new class of application specific TLM processor. The development of an application specific processor based upon the two dimensional shunt node is presented. This gives rise to an efficient, bit serial scatter processor. The implementation of this processor within a complete, application specific TLM system is discussed. The system is based around a unique mapping of the TLM connect routine to hardware. The bit serial scatter processor is modified to allow the modelling of inhomogenous and three dimensional media using the stub loaded shunt node, the symmetrical condensed node and the symmetrical super condensed node TLM schemes. It is shown that all four TLM schemes may be implemented within a single architecture without the introduction of redundant elements through the use of reconfigurable logic. The implications of interfacing this system to a host PC using the PCI bus are discussed. The processor designs are reviewed within the context of the goals set for the work. It is shown that all of the goals were successfully met. The implications and limitations of the processor are discussed. The thesis concludes with recommendations for areas worthy of further study.
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Attari, Amir Reza. "Analysis of interference in high frequency circuits using the transmission line matrix method." Université Joseph Fourier (Grenoble), 2002. http://www.theses.fr/2002GRE10056.
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Dans la compatibilité électromagnétique (CEM) l'analyse des interférences est très importante. Plusieurs progrès technologiques tels que les processeurs ultrarapides et le packaging à faible coût ont contribué à l'importance de cette analyse. La recherche réalisée ici établit une méthode hybride efficace pour l'analyse des interférences. Cette méthode hybride est basée sur la méthode TLM (transmission line matrix) et la formulation des équations intégrales dans le domaine temporel. La démarche employée dans l'étude est la suivante: La méthode TLM est utilisée pour analyser chaque circuit séparement puis les équations intégrales dans le domaine temporel sont mises en oeuvre pour déterminer le rayonnement des circuits et les interférences entre ces derniers. La méthode hybride proposée est très efficace pour des structures qui contiennent des circuits séparés par de grandes distances. A l'inverse de l'application classique de la méthode TLM, la mémoire et le temps de calcul de cette nouvelle méthode son indépendants de la distance entre les circuits. Le blindage par boitiers électromagnétiques est fréquemment employé pour réduire l'émission ou pour améliorer l'immunité des circuits électroniques aux interférences hautes fréquences. Dans cette étude, la méthode TLM est également utilisée pour analyser et concevoir des boitiers électromagnétiques. Le blindage considéré est un boitier rectangulaire avec une ouverture de forme arbitraire. La méthode hybride TLM-Equations intégrales est aussi utilisée pour estimer l'interférence entre deux circuits protégés respectivement par des boitiers de blindage. Des mesures expérimentales sont fournies pour valider les résultats des simulations numériques présentées dans cette thèse.
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Li, Qiyang. "New developments of absorbing boundary algorithm for the transmission line matrix (TLM) method." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6697.
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New developments of Absorbing Boundary (AB) Algorithms for the Transmission Line Matrix (TLM) Method have been presented in this thesis. A new approach has been proposed to obtain the optimized Dissipation Absorbing Boundary Condition (ABC). In this approach, optimization is performed directly on the structure being studied. This approach has been implemented in 2D and 3D TLM. It shows its great advantage especially in 3D because it is unconditionally stable while many other approaches such as extrapolation approach, are unstable. Great efforts have also been made in implementing Liao's ABC in 2D and 3D TLM. This ABC has better absorption than the above approach when the same extra computation space is used. However, this approach is unstable when its order is high. Since Liao's ABC has good absorption and instability, while the Dissipation ABC has good stability and relatively worse absorption, we can properly combine them together to achieve good stability and acceptable absorption. This combination approach has been carefully tested in this thesis and found feasible. Choosing a proper loss tangent for the Dissipation ABC has been discussed. This approach has been implemented in 2D and 3D TLM. (Abstract shortened by UMI.)
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Browne, Daniel R. "Application of multi-core and cluster computing to the Transmission Line Matrix method." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14984.
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The Transmission Line Matrix (TLM) method is an existing and established mathematical method for conducting computational electromagnetic (CEM) simulations. TLM models Maxwell s equations by discretising the contiguous nature of an environment and its contents into individual small-scale elements and it is a computationally intensive process. This thesis focusses on parallel processing optimisations to the TLM method when considering the opposing ends of the contemporary computing hardware spectrum, namely large-scale computing systems versus small-scale mobile computing devices. Theoretical aspects covered in this thesis are: The historical development and derivation of the TLM method. A discrete random variable (DRV) for rain-drop diameter,allowing generation of a rain-field with raindrops adhering to a Gaussian size distribution, as a case study for a 3-D TLM implementation. Investigations into parallel computing strategies for accelerating TLM on large and small-scale computing platforms. Implementation aspects covered in this thesis are: A script for modelling rain-fields using free-to-use modelling software. The first known implementation of 2-D TLM on mobile computing devices. A 3-D TLM implementation designed for simulating the effects of rain-fields on extremely high frequency (EHF) band signals. By optimising both TLM solver implementations for their respective platforms, new opportunities present themselves. Rain-field simulations containing individual rain-drop geometry can be simulated, which was previously impractical due to the lengthy computation times required. Also, computationally time-intensive methods such as TLM were previously impractical on mobile computing devices. Contemporary hardware features on these devices now provide the opportunity for CEM simulations at speeds that are acceptable to end users, as well as providing a new avenue for educating relevant user cohorts via dynamic presentations of EM phenomena.
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Zhang, Guangrong. "The applications of transmission line matrix (TLM) method to the modelling of airborne ultrasonics." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357838.
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Aldabbagh, Ahmed. "Hybrid electric and thermal modelling of semiconductor devices using the transmission line matrix (TLM) methods." Thesis, De Montfort University, 2014. http://hdl.handle.net/2086/10484.
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Increasing the level of semiconductor devices' quality, reliability, and associated system safety is important as a fundamental contributor to overall technical advancement in the electronics sector. However, the growing requirements of optimizing device design for the broadest application areas need an enhanced level of understanding of thermal behaviour, and self-heating in particular, of semiconductor devices under harsh thermal operation conditions. The aim of the research presented in this thesis is to develop and verify a numerical tool to assist in the understanding and the prediction of phenomena that contribute to the ageing and stressing of semiconductor devices. An aged semiconductor device can substantially adversely affect a system's electromagnetic compatibility (EMC) performance and reduce the desired functionality. The chosen method is a co-simulation approach for a linked electrical and thermal model, using the Transmission Line Matrix (TLM) method. This selection is based on having a single method that can simulate both domains, that is intuitive and flexible. The method is enhanced by including electromigration and thermomigration mechanisms as an influential element in the calculation of material properties inside the hybrid solver. The proposed model was subjected to a customized Thermal Cycling Test (TCT) in order to observe device behaviour and comprehend the degradation phenomenon that Abstract appears after accelerated ageing test in RF LDMOS device. The research is a generic step forward, showing that a single TLM 'engine' can be used to model the linked factors in ageing and its effects, namely electrical, and thermal behaviour, that also allows for probabilistic events such as electro/thermo-migration. Further, the method developed in this thesis is applied to two problem areas: • Silicon nanowires, where the thermal radiation effects are addressed by adding an additional shunt conductance to a one-dimensional TLM node structure. The results demonstrate good agreement with previously published results and provide an appropriate tool to solve the internal heating problems and, hence, the degradation caused by thermal factors for future semiconductor devices. • Silicon Carbide Metal-Semiconductor Field Effect Transistor (MESFET) and RF Laterally Diffused Metal Oxide Semiconductor (LDMOS) devices, which are approached as 2D structures, where the probability of occurring electromigration and thermomigration phenomenon in MESFET devices is investigated and the MTTF is shown when the model is subjected to thermal stress. The TCT is applied as a thermal acceleration factor in a MOS device, where the impact on the device IV (current-voltage) characteristic is studied. The results demonstrated good agreement with previous published results.
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Fox, Andrew John. "Invasive varactor tuning of a dielectric resonator." Thesis, Leeds Beckett University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297492.
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El-Masri, Samir D. "Application de la méthode numérique TLM (transmission line matrix) aux ondes acoustiques et à la parole." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0129.
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La plupart des theories actuelles sur la propagation des ondes acoustiques dans le conduit vocal se basent sur le principe des ondes planes (unidimensionnelles) et ne sont valables qu'aux basses frequences. Compte tenu de la difficulte posee par l'etude theorique ou experimentale des ondes acoustiques aux frequences elevees et dans des structures complexes telles que le conduit vocal, les methodes de simulation numerique sont particulierement utiles. La methode numerique tlm (transmission line matrix) a ete developpee initialement pour la simulation de la propagation des ondes electromagnetiques. Les objectifs de la these ont consiste a appliquer cette methode a la propagation des ondes acoustiques dans le conduit vocal. Apres avoir etabli les analogies necessaires entre domaines electrique et acoustique, nous avons valide systematiquement cet outil de simulation par comparaison avec la theorie pour des cavites de forme simple, avec des sources elementaires (monopolaire, dipolaire, quadripolaire). Ceci a permis de montrer que les conditions aux limites utilisees pour simuler l'espace infini sont adequates. Nous avons mis en oeuvre une methode qui permet de mettre en evidence les modes d'ordre superieur de maniere individuelle et etudie leur distribution dans des differences cavites rectangulaires et circulaires. Ce travail a ensuite ete etendu a des modelisations plus detaillees de l'acoustique dans des geometries complexes correspondants a des conduits vocaux realistes, et de participer a l'amelioration de la qualite de la synthese de parole.
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Dindo, Salam Francis. "Design of an interface between gallium arsenide MESFET physical models and the transmission line matrix method." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6578.
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The Transmission Line Matrix (TLM) method has been demonstrated to be capable of simulating the electromagnetic propagation in passive components of monolithic microwave integrated circuits (MMICs), such as microstrip lines, air-bridges, and spiral inductors. The full simulation of MMICs by TLM is hindered by the lack of a GaAs MESFET model. Although SPICE-type lumped element models can be embedded, they are not sufficiently accurate to describe the time dependent response, and they defeat the method since TLM distinguishes itself by being capable of simulating physical structures. In addition, the TLM method cannot simulate a physics-based MESFET model since it cannot model fixed charges in the depletion region, nor can it model the highly non-linear field interactions in the conducting region. The TLM method requires a background solver to assist physics-based MESFET modelling. This thesis presents a novel method for enabling the TLM method to simulate the active region of the MESFET. The device is treated as a two-port where the depletion region is the input, and the channel region is the output. The input of the two-port is fed electric field signals from the gate transmission line. An internal GaAs MESFET solver transforms the input electric field into a voltage waveform, and the channel current and the depletion-channel boundary profile are calculated at every time instant by consideration of the channel doping and geometry. Via suitable interface parameters, the calculated outputs are transformed by individual TLM systems filling the channel into output electric and magnetic fields. The first part of the thesis derives a novel two-dimensional formulation of the TLM method enabling it to simulate a vertical section of the MESFET channel whose thickness is chosen small enough such that the electric field can be considered to be uniform. By controlling the TLM pulse energy, nodes conductivities, and section length, these three interface parameters enable the resultant TLM system to transform the physical characteristics of any infinitesimal section of the channel into electric and magnetic fields. The second part of the thesis derives a numerical time-domain quasi two-dimensional model of a GaAs MESFET with several novel aspects. Time-domain simulation is derived from non-stationary electron velocity response to the electric field. A new method is introduced, called the voltage balance method, to numerically solve the Poisson and current continuity equations at every time instant. In addition, a new time-domain treatment of the dielectric relaxation time constants of the drain and gate circuits enable the method to adopt variable time steps. When these three procedures are combined together, they result in a non-linear GaAs MESFET model which can offer sufficient accuracy and substantial time savings over other techniques. Several practical examples are presented showing TLM computations of (i) the non-stationary carrier velocity response to applied field, (ii) the transient field response to an application of biases into the MESFET, and (iii) the field response to an applied electric field sinusoidal waveform at 10 GHZ. The thesis concludes with several recommendations for future work. The key one is to link this work with the 3-dimensional TLM method by augmenting the output channel fields with those computed by TLM for the passive field interactions in the MESFET source, gate, and drain electrodes.
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Qiu, Bing. "Investigations of dispersion characteristics of microwave/optical guided wave structures by using transmission line matrix method." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6485.
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This thesis presents a new three-dimensional space (3D) condensed node TLM space (Transmission Line Matrix) algorithm for the analysis of dispersion characteristics of microwave/optical guided wave structures. This new algorithm requires much less computer memory and computation time than the conventional 3D condensed node TLM. The application of this new algorithm to the modelling of inhomogeneous, lossy, and unbounded guided structures is investigated. More specifically, techniques such as variable mesh size, absorbing boundaries conditions, are introduced in the algorithm. The error sources, effects due to excitation and output point location are analysed and suggestions for more efficient and accurate modelling of complicated geometries are performed. In particular, special treatment is implemented to accurately model curved boundaries. Finally, the dispersion characteristics of various kinds of rectangular and circular guided structures, are calculated by using this new algorithm. It is found that the results obtained agree fairly well with those observed by theoretical or other proved numerical methods.
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Moniri-Ardakani, Seyed-M. "Application of Transmission Line Matrix (TLM) method to integrated optical lossless/lossy multilayer slab and channel waveguides." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/14866.
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Sivaraman, Nimisha. "Design of magnetic probes for near field measurements and the development of algorithms for the prediction of EMC." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT082/document.
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Au fur et à mesure que le nombre de composants augmente, il existe une forte demande pour identifier les sources de rayonnement pour la prédiction de la compatibilité électromagnétique des circuits électroniques. Le balayage d’une sonde à proximité du circuit est une méthode générale d'identification des sources rayonnantes dans une PCB. La première partie de la thèse consiste à concevoir et à caractériser des sondes magnétiques à haute sensibilité et à haute résolution spatiale. Les sondes conventionnelles basées sur la ligne micro ruban et la configuration coplanaire sont étudiées. À mesure que la longueur de la ligne de transmission connectée à la sonde augmente, le bruit sur le signal de sortie augmente en raison de tensions de mode commun induites par le champ électrique. Afin de supprimer cette tension induite par le champ électrique, une sonde magnétique blindée est conçue et fabriquée à l'aide d'une technologie de circuit imprimé à faible coût (PCB). La performance de la sonde passive est validée dans la bande 1MHz - 1GHz. La sonde blindée est fabriquée sur un substrat FR4 d'une épaisseur de 0,8 mm et se compose de 3 couches avec le signal dans la couche intermédiaire et les couches supérieure et inférieure dédiées aux plans de masse. La taille d'ouverture de la boucle est de 800 μm x 800 μm, avec une résolution spatiale attendue de 400 μm. La haute sensibilité de la sonde est obtenue en intégrant un amplificateur à faible bruit à la sortie de la sonde, ce qui en fait une sonde active. La performance de la sonde blindée avec différentes longueurs de lignes de transmission est faite pour étudier. Une sonde à trois axes capable de mesurer les trois composantes du champ magnétique est également conçue et validée par un balayage en champs proches au-dessus d'une structure standard plan de masse.Dans la deuxième partie, la méthode de la matrice de la ligne de transmission inverse (Inv-TLM) est utilisée, pour reconstruire la distribution source à partir des champs proches (NFS) mesurés au-dessus d'un plan sur la carte PCB. Même si, la résolution de la reconstruction dépend de la longueur d'onde et des paramètres du maillage, la propagation inverse augmente la largeur de l'onde reconstruite. Comme cette méthode corresponde à un problème « mal posé» et entraîne des solutions multiples, nous avons développé une nouvelle méthode basée sur la corrélation croisée bidimensionnelle, qui représente les données de balayage en champ proche sous forme de de dipôles équivalents. Avec cette nouvelle méthode, nous avions pu identifier et de localiser les sources actuelles dans le PCB et est représenté avec des sources équivalentes. La méthode est validée pour les sources avec des orientations différentes. Les données simulées des champs proches utilisant le logiciel commercial CST sont utilisées pour valider les deux méthodes. Le champ lointain prédit à partir de ces sources équivalentes est comparé aux champs simulés<br>As the number of components in a confined volume is increasing, there is a strong demand for identifying the sources of radiation in PCBs and the prediction of EMC of electronic circuits. Electromagnetic near field scanning is a general method of identifying the radiating sources in a PCB. The first part of the thesis consists of the design and characterization of printed circuit magnetic probes with high sensitivity and high spatial resolution. Conventional probes based on microstrip and coplanar configuration is studied. As the length of the transmission line connected to the probe increases, the probe output contains noise due to common mode voltages which is many induced by the electric field. In order to suppress the voltage induced due to the electric field, a shielded magnetic probe is designed and fabricated using low cost printed circuit board (PCB) technology. The performance of the passive probe is calibrated and validated from 1MHz – 1GHz. The shielded probe is fabricated on an FR4 substrate of thickness 0.8mm and consists of 3 layers with the signal in the middle layer and top and bottom layers dedicated to ground planes. The aperture size of the loop is 800µm x 800µm, with an expected spatial resolution of 400 µm. The high sensitivity of the probe is achieved by integrating a low noise amplifier at the output of the probe, hence making an active probe. The performance of the shielded probe with a different length of transmission lines is made to study. When the probe has to be operated above 100MHz, it is found that the transmission lines connected to the probe should be short (around 1.5cmm). For frequencies below 100MH, the length of the lines can be up to 12cm. A three-axis probe which is able to measure the three components of the magnetic field is also designed and validated by near field scanning above a standard wire over the ground structure.In The second part, the inverse transmission line matrix method (Inv-TLM) method is used reconstruct the source distribution from the near field scan (NFS) data above a single in plane on the PCB. Even though the resolution of reconstruction depends on the wavelength and the mesh parameter, the inverse propagation increases the width of the reconstructed wave. As this method is found to be ill posed and results in multiple solutions, we have developed a new method based on the two-dimensional cross-correlation, which represents the near field scan data in terms of the equivalent electric currents of the dipole. With the new method, we are able to identify and locate the current sources in the PCB and are represented by an equivalent source. The method is validated for the current sources with different orientations. The simulated near field data using CST microwave studio is used to validate both the methods. The radiated far field from these equivalent sources is compared with the simulated fields
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Giannopoulos, Antonios. "The investigation of transmission-line matrix and finite-difference time-domain methods for the forward problem of ground probing radar." Thesis, Online version, 1998. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.245873.
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Carvalho, Júnior Carlos Alberto Tenório de. "Desenvolvimento de uma nova ferramenta CAD para o estudo de compatibilidade eletromagnética usando Transmission-Line Matrix - John’s Super Node (TLM-JSN)." reponame:Repositório Institucional da UnB, 2006. http://repositorio.unb.br/handle/10482/6901.
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Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2006.<br>Submitted by Thaíza da Silva Santos (thaiza28@hotmail.com) on 2011-02-11T01:23:35Z
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2006_CarlosAlbertoTenorioCarvalhoJunior.pdf: 2629276 bytes, checksum: bcaf33b03adf4a0a77745682f35bcf90 (MD5)<br>Este trabalho apresenta um novo conceito para a aceleração do método TLM bidimensional (TLM-2D). A técnica baseia-se na utilização de saltos controlados no passo de tempo em conjunto com a redução de ordem de modelo, obtendo assim um processamento mais rápido. Estes saltos são numericamente estáveis e podem resultar em considerável redução na utilização do processador. Para tornar o método mais eficiente emprega-se a redução de ordem de modelo por meio da decomposição de Schur ou via decomposição em autovalores, utilizando a transformada Z. Além disso, apresenta-se aplicações da envoltória complexa na modelagem numérica utilizando o método TLM-JSN (Transmission Line Matrix - John´s Super Node) e adaptação da técnica de diakópticas na modelagem TLMJSN. A metodologia é validada através de comparações com o método TLM convencional, mediante o cálculo de diversas estruturas.
_________________________________________________________________________________ ABSTRACT<br>This work presents a new concept for the acceleration of the TLM method. The technique is based on the use of controlled timestep jumps together with model order reduction. This results in faster processing. These jumps are numerically stable and can result in considerable computational savings. The method can be optimized through model order reduction using Schur decomposition or through Z-transform eigenvalue decomposition. In addittion, this work presents the application of the complex envelope in TLM-JSN (Transmission-Line Matrix - John’s Super Node) together with the appllication of diakoptics techniques. The methodology is validated through comparisons with the method TLM conventional, by the calculation of several structures.
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Eswarappa. "New developments in the transmission line matrix and the finite element methods for numerical modeling of microwave and millimeter wave structures." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5807.
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New and efficient numerical modeling concepts and procedures based on Transmission Line Matrix and Finite Element methods have been developed for the analysis of generalized microwave and millimeter-wave structures. An algorithm, based on a vectorial Finite Element approach, has been developed to determine the dispersion characteristics, field distributions, pseudo-impedances and, losses of shielded transmission media of arbitrary cross-section. The structures analysed with this algorithm include dielectrically loaded ridged waveguides, bilateral finlines in rectangular and circular waveguide enclosures and ridged finlines. The major contributions to the literature are the estimation of losses of bilateral finlines in rectangular waveguide enclosures, the effect of substrate bending and mounting grooves on the dispersion characteristics, the study of finlines in circular waveguide enclosures, and, the analysis of a new modified finline structure called "Ridged Finline". New algorithms to apply the principles of Diakoptics to the TLM method for field partitioning in large structures have been developed. Diakoptics leads to considerable reduction in memory and CPU requirements for large structures since it allows numerical preprocessing of parts of a large electromagnetic structure which remain unchanged during an analysis and optimization procedure. A space interpolation technique based on the transverse field distribution of the propagation mode has been proposed for efficient field partitioning in single-mode structures. Frequency dispersive boundaries are represented in the time domain by their characteristic impulse response or numerical/discrete Green's function. This discrete Green's function has been named the "Johns matrix" in honour of the late P. B. Johns, pioneer of TLM and time domain Diakoptics. The parasitic reflections from the absorbing boundaries in 3-D structures, due to the finite space and time discretization have been reduced to less than one percent by exponentially tapering the impulse response, or Johns Matrix, of frequency dispersive boundaries. This allows wideband S--parameter extraction of waveguide discontinuities and components from a single impulsive TLM simulation. This tapered impulse response has been named the "Tapered Johns Matrix".
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Souza, Junior Newton Vieira de [UNESP]. "Um modelo de linha de transmissão bifásica desenvolvido diretamente no domínio das fases." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/87102.
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souzajunior_nv_me_ilha.pdf: 788447 bytes, checksum: 8b9466a049a4bdb01e9292faf0c87bb0 (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Sabe-se que uma linha de transmissão polifásica pode ser representada no domínio modal, por seus n modos de propagação que se comportam como sendo n linhas monofásicas independentes. Uma vez calculadas as correntes e tensões no domínio modal, as mesmas são convertidas para o domínio das fases por meio de uma matriz de transformação modal. A matriz de transformação modal é uma matriz cujos elementos são escritos em função dos parâmetros longitudinais e transversais da linha, variam em função da frequência e, geralmente, são obtidos por meio de métodos numéricos. Deste modo, diz-se que o modelo obtido é um modelo numérico de linha. Neste trabalho foi feita uma abordagem a respeito de um modelo analítico de linha de transmissão bifásica. O modelo proposto utiliza também a representação modal, mas a matriz de transformação será obtida analiticamente em função dos parâmetros da linha. Deste modo, foi possível obter, analiticamente, relações entre as correntes e tensões de fase da linha baseando-se unicamente nos parâmetros longitudinais e transversais da mesma<br>It is know that polyphase transmission line can be represented in the modal domain its n propagation modes that behave as n independent single-phase lines. Once calculated the currents and voltages in the modal domain, they are converted into the realm of the phases by means of a modal transformation matrix. The modal transformation matrix is a matrix whose elements re written against the parameters of longitudinal and cross the and they are usually obtained by numerical methods. In this paper an approach was made on an analytical model of two-phase transmission line. The proposed model uses the modal representation, but the transmission matrix obtained analytical in terms of line parameters. The development of the analytical model will be based on the modal model. Thus, initially will be obtained analytically, a modal matrix decomposition that allows to calculate analytically the eigenvalues of the product [Z][Y] line. Once obtained the eigenvalues it possible to abtain the modes of propagation and characteristic impedance of the line modes. Then, using the solutions algebraic differential equation of a single-phase line, we abtain the equations of currents and voltages of each of modes of spread of the row. In a final step, the equations of modal currents and voltages are converted into the realm of the phases, resulting in algebraic equations that can calculate the currents and phase voltages of the line in the frequency domain
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Chobeau, Pierre. "Modeling of sound propagation in forests using the transmission line matrix method : study of multiple scattering and ground effects related to forests." Thesis, Le Mans, 2014. http://www.theses.fr/2014LEMA1016/document.
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Les trois principaux phénomènes acoustiques propres au milieu forestier nécessitant d'être pris en compte sont (1) l'absorption due à la présence d'un sol multi-couche, (2) la diffusion multiple due à la présence d'obstacles tels que les troncs, (3) les effets micro-météorologiques rattachés aux variations des gradients de vitesse de vent et de température. Parmi les méthodes numériques de référence, la méthode des lignes de transmission (TLM), semble particulièrement adaptée pour la modélisation de la propagation acoustique en présence de forêt, à condition de procéder à de nouveaux développements. La première nécessité pour l'adaptation de la méthode TLM aux simulations acoustiques sur de grandes distances est la définition de couches absorbantes, permettant de tronquer efficacement le domaine d'étude, sans introduire de réflexions parasites. La formulation ainsi développée dans le cadre de la thèse est rigoureusement équivalente à l'équation de propagation des ondes amorties, et se traduit dans la méthode TLM par l'introduction et l'optimisation d'un terme de dissipation. L'étape suivante a consisté à vérifier la capacité de la méthode TLM à modéliser les phénomènes de diffusion par des cylindres. L’une des originalités introduites dans cette thèse réside dans le placement des éléments diffuseurs, à partir de lois de distribution aléatoire et de Gibbs, permettant ainsi de définir des répartitions proches de celles rencontrées en forêt. À titre d'application de la méthode développée dans le cadre de la thèse, une étude paramétrique a été réalisée afin de définir les conditions pour lesquelles une forêt peut également être considérée comme un dispositif de protection<br>The prediction of sound propagation in presence of forest remains a major challenge for the outdoor sound propagation community. Reference numerical models such as the Transmission Line Matrix (TLM) method can be developed in order to accurately predict each acoustical phenomenon that takes place inside forest. The first need for the TLM method is an efficient theory-based absorbing layer formulation that enables the truncation of the numerical domain. The two proposed absorbing layer formulations are based on the approximation of the perfectly matched layer theory. The most efficient proposed formulation is shown to be equivalent to wave propagation in a lossy media, which, in the TLM method formulation, is introduced using an additional dissipation term. Then, the ability of the TLM method for the simulation of scattering is studied comparing the numerical results to both analytical solutions and measurements on scale models. Lastly, the attenuation of acoustic levels by a simplified forest is numerically studied using several arrangements of cylinders placed normal to either reflecting or absorbing ground. It is observed that randomly spaced arrangements are more inclined to attenuate acoustic waves than periodic arrangements. Moreover, the sensitivity to the density, the length of the array and the ground absorption is tested. The main trend shows that the density and the distribution are two important parameters for the attenuation. In future work, it can be interesting to look at the sensitivity of each parameter. This study could then be used to relate the morphology (i.e. distribution, density, length) of a forest to the acoustical properties of the forest
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Aumond, Pierre. "Modélisation numérique pour l'acoustique environnementale : simulation de champs météorologiques et intégration dans un modèle de propagation." Phd thesis, Université du Maine, 2011. http://tel.archives-ouvertes.fr/tel-00743330.
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Il existe aujourd'hui un enjeu sociétal majeur à s'intéresser à la propagation du son en milieu extérieur etnotamment, dans notre contexte, à diminuer l'incertitude sur l'estimation des niveaux sonores et améliorer ainsi laprécision des diverses analyses, du bureau d'étude à l'institut de recherche. Dans le cadre de l'acoustiqueenvironnementale, l'influence des conditions météorologiques sur la propagation acoustique en milieu extérieurpeut être importante. Il est donc nécessaire d'appréhender et de quantifier les phénomènes météorologiques demicro-échelles que l'on observe dans la couche limite atmosphérique.Dans ce but, le modèle météorologique de recherche de Météo-France (Meso-NH) a été utilisé. Après avoircomparé les résultats de ce modèle à très fine résolution (de l'ordre du mètre) à l'aide des bases de données de deuxcampagnes expérimentales (Lannemezan 2005 et la Station de Long Terme), il s'est avéré nécessaire de développercet outil en intégrant la prise en compte de la force de traînée des arbres. Dès lors, les résultats issus de Meso-NH surles champs de vent, de température et d'énergie cinétique turbulente aparraissent satisfaisants. Ces informationssont par la suite utilisées en données d'entrée du modèle de propagation acoustique.Le modèle acoustique temporel utilisé est basé sur la méthode Transmission Line Matrix (TLM). Sondéveloppement a été effectué dans le but d'être appliqué à la propagation acoustique en milieu extérieur : prise encompte du relief, de différents types de sol, des conditions atmosphériques, etc. La validation numérique de laméthode TLM, par comparaison avec d'autres modèles (analytique et numérique de type Equation Parabolique), apermis de montrer la pertinence de son utilisation dans le cadre de l'acoustique environnementale.Enfin, à l'aide de ces modèles, des niveaux sonores simulés sous différentes conditions de propagation(favorables, défavorables, homogènes) ont été comparés aux mesures in-situ réalisées lors de la campagneexpérimentale de Lannemezan 2005. Les résultats se sont avérés très satisfaisants au regard de la variabilité desphénomènes observés. Cependant, l'utilisation des champs issus d'un modèle micro-météorologique de type Meso-NH reste délicate du fait de la forte sensibilité du niveau sonore aux profils verticaux de célérité du son. L'étude defaisabilité sur une expérience plus complexe (la Station de Long Terme) est encourageante et, à condition de disposerd'importants moyens de calculs, elle permet de considérer la TLM comme une nouvelle méthode de référence etainsi, d'envisager d'élargir son domaine d'utilisation à d'autres applications.
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Souza, Junior Newton Vieira de. "Um modelo de linha de transmissão bifásica desenvolvido diretamente no domínio das fases /." Ilha Solteira : [s.n.], 2011. http://hdl.handle.net/11449/87102.
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Orientador: Sérgio Kurokava<br>Banca: Luiz Fernando Bovolato<br>Banca: José Carlos da Costa Campos<br>Resumo: Sabe-se que uma linha de transmissão polifásica pode ser representada no domínio modal, por seus n modos de propagação que se comportam como sendo n linhas monofásicas independentes. Uma vez calculadas as correntes e tensões no domínio modal, as mesmas são convertidas para o domínio das fases por meio de uma matriz de transformação modal. A matriz de transformação modal é uma matriz cujos elementos são escritos em função dos parâmetros longitudinais e transversais da linha, variam em função da frequência e, geralmente, são obtidos por meio de métodos numéricos. Deste modo, diz-se que o modelo obtido é um modelo numérico de linha. Neste trabalho foi feita uma abordagem a respeito de um modelo analítico de linha de transmissão bifásica. O modelo proposto utiliza também a representação modal, mas a matriz de transformação será obtida analiticamente em função dos parâmetros da linha. Deste modo, foi possível obter, analiticamente, relações entre as correntes e tensões de fase da linha baseando-se unicamente nos parâmetros longitudinais e transversais da mesma<br>Abstract: It is know that polyphase transmission line can be represented in the modal domain its n propagation modes that behave as n independent single-phase lines. Once calculated the currents and voltages in the modal domain, they are converted into the realm of the phases by means of a modal transformation matrix. The modal transformation matrix is a matrix whose elements re written against the parameters of longitudinal and cross the and they are usually obtained by numerical methods. In this paper an approach was made on an analytical model of two-phase transmission line. The proposed model uses the modal representation, but the transmission matrix obtained analytical in terms of line parameters. The development of the analytical model will be based on the modal model. Thus, initially will be obtained analytically, a modal matrix decomposition that allows to calculate analytically the eigenvalues of the product [Z][Y] line. Once obtained the eigenvalues it possible to abtain the modes of propagation and characteristic impedance of the line modes. Then, using the solutions algebraic differential equation of a single-phase line, we abtain the equations of currents and voltages of each of modes of spread of the row. In a final step, the equations of modal currents and voltages are converted into the realm of the phases, resulting in algebraic equations that can calculate the currents and phase voltages of the line in the frequency domain<br>Mestre
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Faure, Olivier. "Analyse numérique et expérimentale de la propagation acoustique extérieure : effets de sol en présence d'irrégularités de surface et méthodes temporelles." Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0041/document.
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Dans le contexte de l’amélioration des modèles de prévision en acoustique extérieure, ces travaux de thèse se focalisent sur la modélisation des effets des irrégularités de la surface du sol sur la propagation acoustique. Pour ce faire, des méthodes numériques temporelles sont utilisées : d’une part, la méthode FDTD basée sur la résolution des équations de l’acoustique par des schémas aux différences finies, et d’autre part, la méthode des lignes de transmission (TLM). La modélisation des effets de la rugosité de surface est abordée en considérant le formalisme de l’impédance effective. Deux modèles d’impédance effective sont étudiés : le premier caractérise les effets d’une rugosité déterministe constituée de diffuseurs de géométrie constante, le second caractérise les effets moyens d’une rugosité aléatoire définie par un spectre de rugosité. Ce second modèle est validé expérimentalement par une campagne de mesures en salle semi-anéchoïque, audessus de surfaces rugueuses dont la rugosité a été définie très précisément. Les deux modèles d’impédance effective sont également validés par des simulations numériques FDTD et TLM. La possibilité d’implémenter ces conditions d’impédance effective dans les deux codes temporels est ainsi montrée, ce qui permet de modéliser les effets de la rugosité sans avoir à réaliser un maillage précis du profil des hauteurs de la surface du sol. Une campagne de mesures de l’impédance de différents terrains est réalisée afin d’étudier les effets de la variabilité spatiale et saisonnière de l’impédance sur la prévision des niveaux sonores. Les impédances mesurées lors de cette campagne sont également utilisées comme des données d’entrée réalistes pour le code TLM, afin de simuler et d’étudier les effets de la propagation acoustique au-dessus d’un sol hétérogène présentant une impédance spatialement variable<br>In the context of prediction models improvement for outdoor sound propagation, this work focuses on the modelling of the effects of ground irregularities on sound propagation. Time-domain numerical methods are used: on one hand, the solving of the governing equations by finite difference schemes (FDTD method), and on the other hand, the transmission line matrix (TLM) method. Effective impedance is considered to model the effects of surface roughness. Two effective impedance models are studied: the first one takes into account the effects of a deterministic roughness formed by scatterers of constant geometry, the second one takes into account the mean effects of a random roughness defined by a roughness spectrum. This second model is validated experimentally by a measurements campaign carried out in a semi-anechoic chamber, above rough surfaces whose roughness profiles were precisely designed. The two effective impedance models are also validated by FDTD and TLM simulations. The possibility to use the effective impedances directly into the numerical methods is then shown, allowing the modelling of roughness effects without meshing the exact height profile of the ground surface. A measurements campaign of the impedance of different grounds is performed in order to assess the effects of space and seasonal variability of the impedance on the sound levels predictions. The results of this campaign are also used as realistic entry data for the TLM code, and the propagation above a heterogeneous ground showing spatially variable impedance is simulated
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Heleno, Evandro Fernandes. "Avaliação de câmaras reverberantes através do método numérico TLM." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-01122006-121507/.
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O presente trabalho tem por objetivo avaliar o comportamento dos campos eletromagnéticos no interior de câmaras reverberantes de modos misturados através do método numérico TLM (Transmission Line Matrix). Inicialmente, apresenta-se uma descrição dos diversos tipos de câmaras aplicáveis na avaliação de desempenho de compatibilidade eletromagnética de equipamentos e sistemas elétricos, destacando-se suas principais características físicas e geométricas, com ênfase nas câmaras reverberantes. Os aspectos teóricos relacionados à descrição do método TLM são detalhados e sua aplicação na avaliação do ambiente eletromagnético das câmaras é então abordada. Diversos resultados são apresentados, considerando-se configurações pré-definidas de câmaras reverberantes, ressaltando-se a definição e cálculo de índices de mérito, bem como os principais aspectos relacionados à representação e definição de critérios adotados nas simulações destas.<br>The aim of this report is the evaluation of the behavior of electromagnetic fields inside reverberation chambers by means of Transmission Line Modeling (TLM). Initially, it is presented a description of several kinds of chambers applicable for electromagnetic compatibility tests followed by a more detailed description regarding reverberation chambers. Theoretical aspects of TLM method and its application for electromagnetic fields solution are covered. Some results are presented, considering pre-defined reverberation chambers configurations, highlighting some merit indicators and the main aspects adopted on its simulation.
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Cox, Gavin J. "Techniques for pattern control of a dielectric rod antenna suitable for use in mobile communications." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/12693.
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This thesis describes the development of antennas suitable for mobile coinmunication systems based on a dielectric rod antenna fed from circular waveguide. Pattern control of the antenna is implemented using a combination of Frequency Selective Surface (FSS) elements and metallic endcaps placed on the antenna Both linear and circular polarised feeds have been made for these antennas to ensure they are suitable for a wide range of applications. The suitability of the dominant and next, higher order, waveguide mode were investigated and conclusions drawn as to their suitability for this type of antenna. The antennas were extensively modelled using a commercial TLM based solver and the results of these simulations were compared to the comprehensive set of antenna pattern measurements and S-parameter measurements obtained for the prototype antennas.
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Chaaban, Mohamed. "Contribution à l'étude du rayonnement des conducteurs filaires." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00669531.
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Le travail de recherche proposé dans ce manuscrit consiste à modéliser le rayonnement électromagnétique de conducteurs filaires. En effet l'estimation du rayonnement est un enjeu majeur et l'utilisation de modèles exacts nous semble nécessaire. On propose donc dans ce mémoire une approche analytique qui permet de quantifier les niveaux de champs électromagnétiques rayonnés par les systèmes filaires. Dans un premier temps nous proposons un modèle analytique du calcul du champ électromagnétique rayonné par un système filaire basé sur un développement approfondi des équations de Maxwell. Ce formalisme est issu de la formulation intégrale du potentiel vecteur émis par une antenne filaire dont on supposera connu la distribution de courant. Le modèle analytique ainsi obtenu permet d'estimer aisément les champs sans avoir besoin de discrétiser ni le support de transmission ni l'espace d'observation. Pour enrichir notre modèle nous avons ensuite envisagé les cas où la distribution du courant le long des conducteurs était issu, soit de la théorie des lignes soit d'une simulation numérique basée sur la théorie des antennes, soit de mesures. Dans le cas où c'est la théorie des lignes qui est à la base de la détermination des courants distribués, nous proposons un formalisme analytique du champ électromagnétique rayonné basé uniquement sur la seule connaissance des courants et de leurs dérivées aux extrémités des conducteurs. Nous avons également montré que ce formalisme s'extrapole aisément au cas d'un réseau multifilaire. Dans le cas où la théorie des antennes ou des mesures sont à la base de la connaissance des courants distribués, on identifie ce courant par quelques pôles et résidus grâce à la méthode d'identification Matrix Pencil (MP). Le champ électromagnétique rayonné s'exprime alors par une série finie de termes intégrales. Ce formalisme reste analytique et présente l'avantage d'être adapté aux approches paramétriques et d'optimisations. Nos travaux de recherche ouvrent des perspectives de reconstruction de la distribution du courant par Matrix Pencil à partir de la connaissance du courant et de ses premières dérivées spatiales aux seules extrémités des conducteurs. Le champ électromagnétique rayonné sera alors déduit de notre modèle.
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Alexandru, Mihai. "Efficient large electromagnetic simulation based on hybrid TLM and modal approach on grid computing and supercomputer." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2012. http://tel.archives-ouvertes.fr/tel-00797061.
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Dans le contexte des Sciences de l'Information et de la Technologie, un des challenges est de créer des systèmes de plus en plus petits embarquant de plus en plus d'intelligence au niveau matériel et logiciel avec des architectures communicantes de plus en plus complexes. Ceci nécessite des méthodologies robustes de conception afin de réduire le cycle de développement et la phase de prototypage. Ainsi, la conception et l'optimisation de la couche physique de communication est primordiale. La complexité de ces systèmes rend difficile leur optimisation notamment à cause de l'explosion du nombre des paramètres inconnus. Les méthodes et outils développés ces dernières années seront à terme inadéquats pour traiter les problèmes qui nous attendent. Par exemple, la propagation des ondes dans une cabine d'avion à partir des capteurs ou même d'une antenne, vers le poste de pilotage est grandement affectée par la présence de la structure métallique des sièges à l'intérieur de la cabine, voir les passagers. Il faut, donc, absolument prendre en compte cette perturbation pour prédire correctement le bilan de puissance entre l'antenne et un possible récepteur. Ces travaux de recherche portent sur les aspects théoriques et de mise en oeuvre pratique afin de proposer des outils informatiques pour le calcul rigoureux de la réflexion des champs électromagnétiques à l'intérieur de très grandes structures . Ce calcul implique la solution numérique de très grands systèmes inaccessibles par des ressources traditionnelles. La solution sera basée sur une grille de calcul et un supercalculateur. La modélisation électromagnétique des structures surdimensionnées par plusieurs méthodes numériques utilisant des nouvelles ressources informatiques, hardware et software, pour dérouler des calculs performants, représente le but de ce travail. La modélisation numérique est basée sur une approche hybride qui combine la méthode Transmission-Line Matrix (TLM) et l'approche modale. La TLM est appliquée aux volumes homogènes, tandis que l'approche modale est utilisée pour décrire les structures planaires complexes. Afin d'accélérer la simulation, une implémentation parallèle de l'algorithme TLM dans le contexte du paradigme de calcul distribué est proposé. Le sous-domaine de la structure qui est discrétisé avec la TLM est divisé en plusieurs parties appelées tâches, chacune étant calculée en parallèle par des processeurs différents. Pour accomplir le travail, les tâches communiquent entre elles au cours de la simulation par une librairie d'échange de messages. Une extension de l'approche modale avec plusieurs modes différents a été développée par l'augmentation de la complexité des structures planaires. Les résultats démontrent les avantages de la grille de calcul combinée avec l'approche hybride pour résoudre des grandes structures électriques, en faisant correspondre la taille du problème avec le nombre de ressources de calcul utilisées. L'étude met en évidence le rôle du schéma de parallélisation, cluster versus grille, par rapport à la taille du problème et à sa répartition. En outre, un modèle de prédiction a été développé pour déterminer les performances du calcul sur la grille, basé sur une approche hybride qui combine une prédiction issue d'un historique d'expériences avec une prédiction dérivée du profil de l'application. Les valeurs prédites sont en bon accord avec les valeurs mesurées. L'analyse des performances de simulation a permis d'extraire des règles pratiques pour l'estimation des ressources nécessaires pour un problème donné. En utilisant tous ces outils, la propagation du champ électromagnétique à l'intérieur d'une structure surdimensionnée complexe, telle qu'une cabine d'avion, a été effectuée sur la grille et également sur le supercalculateur. Les avantages et les inconvénients des deux environnements sont discutés.
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Aumond, Pierre, Michel Berengier, Benoit Gauvreau, Christine Lac, and Valery Masson. "Modélisation numérique pour l'acoustique environnementale : simulation de champs météorologiques et intégration dans un modèle de propagation." Phd thesis, Université du Maine, 2011. http://tel.archives-ouvertes.fr/tel-00737449.
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Il existe aujourd'hui un enjeu sociétal majeur à s'intéresser à la propagation du son en milieu extérieur et notamment, dans notre contexte, à diminuer l'incertitude sur l'estimation des niveaux sonores et améliorer ainsi la précision des diverses analyses, du bureau d'étude à l'institut de recherche. Dans le cadre de l'acoustique environnementale, l'influence des conditions météorologiques sur la propagation acoustique en milieu extérieur peut être importante. Il est donc nécessaire d'appréhender et de quantifier les phénomènes météorologiques de micro-échelles que l'on observe dans la couche limite atmosphérique. Dans ce but, le modèle météorologique de recherche de Météo-France (Meso-NH) a été utilisé. Après avoir comparé les résultats de ce modèle à très fine résolution (de l'ordre du mètre) à l'aide des bases de données de deux campagnes expérimentales (Lannemezan 2005 et la Station de Long Terme), il s'est avéré nécessaire de développer cet outil en intégrant la prise en compte de la force de traînée des arbres. Dès lors, les résultats issus de Meso-NH sur les champs de vent, de température et d'énergie cinétique turbulente aparraissent satisfaisants. Ces informations sont par la suite utilisées en données d'entrée du modèle de propagation acoustique. Le modèle acoustique temporel utilisé est basé sur la méthode Transmission Line Matrix (TLM). Son développement a été effectué dans le but d'être appliqué à la propagation acoustique en milieu extérieur : prise en compte du relief, de différents types de sol, des conditions atmosphériques, etc. La validation numérique de la méthode TLM, par comparaison avec d'autres modèles (analytique et numérique de type Equation Parabolique), a permis de montrer la pertinence de son utilisation dans le cadre de l'acoustique environnementale. Enfin, à l'aide de ces modèles, des niveaux sonores simulés sous différentes conditions de propagation (favorables, défavorables, homogènes) ont été comparés aux mesures in-situ réalisées lors de la campagne expérimentale de Lannemezan 2005. Les résultats se sont avérés très satisfaisants au regard de la variabilité des phénomènes observés. Cependant, l'utilisation des champs issus d'un modèle micrométéorologique de type Meso-NH reste délicate du fait de la forte sensibilité du niveau sonore aux profils verticaux de célérité du son. L'étude de faisabilité sur une expérience plus complexe (la Station de Long Terme) est encourageante et, à condition de disposer d'importants moyens de calculs, elle permet de considérer la TLM comme une nouvelle méthode de référence et ainsi, d'envisager d'élargir son domaine d'utilisation à d'autres applications.
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Khalil, Fadi. "Modélisation Multi-échelles : de l'Electromagnétisme à la Grille." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2009. http://tel.archives-ouvertes.fr/tel-00448305.
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Les performances des outils numériques de simulation électromagnétique de structures complexes, i.e., échelles multiples, sont souvent limitées par les ressources informatiques disponibles. De nombreux méso-centres, fermes et grilles de calcul, se créent actuellement sur les campus universitaires. Utilisant ces ressources informatiques mutualisées, ce travail de thèse s'attache à évaluer les potentialités du concept de grille de calcul (Grid Computing) pour la simulation électromagnétique de structures multi-échelles. Les outils numériques de simulation électromagnétique n'étant pas conçus pour être utilisés dans un environnement distribué, la première étape consistait donc à les modifier afin de les déployer sur une grille de calcul. Une analyse approfondie a ensuite été menée pour évaluer les performances des outils de simulation ainsi déployés sur l'infrastructure informatique. Des nouvelles approches pour le calcul électromagnétique distribué avec ces outils sont présentées et validées. En particulier, ces approches permettent la réalisation de simulation électromagnétique de structures à échelles multiples en un temps record et avec une souplesse d'utilisation.
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Barlabé, i. Dalmau Antoni. "Anàlisi de discontinuïtats finline." Doctoral thesis, Universitat Politècnica de Catalunya, 1996. http://hdl.handle.net/10803/6936.
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En esta tesis se han desarrollado los siguientes métodos numéricos para el análisis de estructuras planares, especialmente finline, en la banda de microondas y ondas milimétricas: <br/>-el método de las líneas con discretizacion uniforme y no uniforme.<br/> -el método de los elementos finitos aplicado al análisis de guías homogéneas e inhomogeneas.<br/> -el método de la matriz de lineas de transmisión tridimensional. <br/>-el método de la matriz se generalizada para el análisis de estructuras uniformes y discontinuidades planares. <br/>-el método del dominio espectral para el análisis de estructuras planares uniformes.<br/> -el método del circuito planar con corrección de la dispersión. <br/><br/>Se ha elegido el método de la resonancia transversal generalizado como el mas idóneo para el análisis preciso y rápido de discontinuidades finline con un mínimo de recursos informáticos. Se ha desarrollado incluyendo el carácter singular de los campos en las aristas de la estructura, consiguiéndose minimizar el fenómeno de la convergencia relativa y obteniéndose resultados precisos con expansiones reducidas de las funciones modales que representan los campos, validándose los resultados obtenidos al analizar diversas estructuras con medidas experimentales.
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Sasse, Hugh Granville. "Enhancing numerical modelling efficiency for electromagnetic simulation of physical layer components." Thesis, De Montfort University, 2010. http://hdl.handle.net/2086/4406.
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The purpose of this thesis is to present solutions to overcome several key difficulties that limit the application of numerical modelling in communication cable design and analysis. In particular, specific limiting factors are that simulations are time consuming, and the process of comparison requires skill and is poorly defined and understood. When much of the process of design consists of optimisation of performance within a well defined domain, the use of artificial intelligence techniques may reduce or remove the need for human interaction in the design process. The automation of human processes allows round-the-clock operation at a faster throughput. Achieving a speedup would permit greater exploration of the possible designs, improving understanding of the domain. This thesis presents work that relates to three facets of the efficiency of numerical modelling: minimizing simulation execution time, controlling optimization processes and quantifying comparisons of results. These topics are of interest because simulation times for most problems of interest run into tens of hours. The design process for most systems being modelled may be considered an optimisation process in so far as the design is improved based upon a comparison of the test results with a specification. Development of software to automate this process permits the improvements to continue outside working hours, and produces decisions unaffected by the psychological state of a human operator. Improved performance of simulation tools would facilitate exploration of more variations on a design, which would improve understanding of the problem domain, promoting a virtuous circle of design. The minimization of execution time was achieved through the development of a Parallel TLM Solver which did not use specialized hardware or a dedicated network. Its design was novel because it was intended to operate on a network of heterogeneous machines in a manner which was fault tolerant, and included a means to reduce vulnerability of simulated data without encryption. Optimisation processes were controlled by genetic algorithms and particle swarm optimisation which were novel applications in communication cable design. The work extended the range of cable parameters, reducing conductor diameters for twisted pair cables, and reducing optical coverage of screens for a given shielding effectiveness. Work on the comparison of results introduced ―Colour maps‖ as a way of displaying three scalar variables over a two-dimensional surface, and comparisons were quantified by extending 1D Feature Selective Validation (FSV) to two dimensions, using an ellipse shaped filter, in such a way that it could be extended to higher dimensions. In so doing, some problems with FSV were detected, and suggestions for overcoming these presented: such as the special case of zero valued DC signals. A re-description of Feature Selective Validation, using Jacobians and tensors is proposed, in order to facilitate its implementation in higher dimensional spaces.
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Tolfo, Daniela de Rosso. "Ondas planas e modais em sistemas distribuídos elétricos e mecânicos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/170402.
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Neste trabalho, são caracterizadas as soluções do tipo ondas planas e modais de modelos matemáticos referentes à teoria de linhas de transmissão, com e sem perdas, e à teoria de vigas, modelo de Timoshenko e modelo não local de Eringen. Os modelos são formulados matricialmente, e as ondas em questão são determinadas em termos da base gerada pela resposta matricial fundamental de sistemas de equações diferenciais ordinárias de primeira, segunda e quarta ordem. A resposta matricial fundamental é utilizada numa forma fechada que envolve o acoplamento de um número finito de matrizes e uma função escalar geradora e suas derivadas. A função escalar geradora é bem comportada para mudanças em torno de frequências críticas e sua robustez é exibida através da técnica de Liouville. As ondas modais são decompostas em termos de uma parte que viaja para frente e uma parte que viaja para trás. Essa decomposição é utilizada para fornecer matrizes de reflexão e transmissão em descontinuidades e condições de contorno. No contexto das linhas de transmissão são consideradas uma junção de linhas com impedâncias características diferentes ou uma carga em uma extremidade da linha. Na teoria de Timoshenko são consideradas uma fissura ou condições de contorno em uma das extremidades. Exemplos numéricos com descontinuidade são considerados na viga. Na teoria de linhas de transmissão exemplos com multicondutores são considerados e observações são realizadas sobre a decomposição das ondas modais. No modelo não local de Eringen, para vigas bi-apoiadas é discutida a existência do segundo espectro de frequências.<br>Plane type solutions and modal waves of mathematical models, which refer to transmission lines theory, both lossless and lossy, and to beam theory, using both Timoshenko and nonlocal Eringen models, are being characterized in this work. The models are formulated in matrix form, and the waves are determined in terms of matrix basis generated by fundamental matrix response of systems of ordinary differential equations of first, second and fourth order. The fundamental matrix response is used in the closed-form, which involve the coupling between a number finite of matrices of a generating scalar function and its derivatives. The generating scalar function is well behaved for changes around critical frequencies and its robustness is exhibited through the Liouville technique. Modal waves are decomposed in forward and backward parts. This decomposition is used for providing reflection and transmission matrices when dealing with discontinuities and boundary conditions. In the context of transmission lines junction of lines with different characteristic impedances or a load at one end of the line are being considered. In Timoshenko’s theory the crack problem or boundary conditions at one end are also being considered. Numerical examples with discontinuities are considered in the context of beams. Numerical examples with discontinuities and boundary value problems were approached using modal wave decomposition. In transmission line theory examples with multiconductors are considered and observations are made about decomposition of the modal waves. In the nonlocal of Eringen model, for bi-supported beams, the existence of the second frequency spectrum is discussed.
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Zheng, Tianyu. "Periodic SIW lines with degenerate band edge for the excitation of giant resonances." Thesis, Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=http://theses-intra.upmc.fr/modules/resources/download/theses/2020SORUS087.pdf.
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Dans cette thèse, nous décrivons la conception de guides d'onde intégrés au substrat (substrate integrated substrates, SIW) qui supportent des dégénérescences du quatrième ordre en bord de bandes interdites du diagramme de Brillouin (degenerate band edge, DBE). Le DBE conduit à des « résonances géantes » et à résonateurs à fort facteur de qualité. Le choix de la technologie SIW peut permettre l'utilisation du concept DBE dans les circuits intégrés hyperfréquences et aux ondes millimétriques. Les applications de ce concept sont nombreuses : résonateurs à fort facteur de qualité, oscillateurs robustes aux charges externes, capteurs à directivité et sensibilité élevées. Ici nous caractérisons un type de cellules élémentaires qui permet de concevoir un point DBE après une analyse de plusieurs types de cellules. Sur la base de ces résultats, plusieurs conceptions de SIW qui supportent une DBE sont présentées. On considère l'influence des pertes, des perturbations géométriques et l’effet dû à la troncature de la ligne périodique. Les caractéristiques DBE typiques, telles que l'amplification du champ et une forte augmentation du facteur Q et du retard de groupe par rapport au nombre de cellules sont observées dans un résonateur tronqué, dans des situations sans perte et avec perte. Des transitions nécessaires pour alimenter les lignes SIWs sont conçues et permettent d’effectuer les mesures de prototypes qui valident pleinement les analyses théoriques. Enfin, la procédure de conception est également appliquée à un guide d'ondes intégré multicouche, particulièrement adapté aux applications à ondes millimétrique, montrant la versatilité de la méthodologie proposée<br>In this thesis, we describe the synthesis of periodic substrate-integrated waveguide (SIW) supporting degenerate band edge (DBE) points. The DBE point is a special fourth-order degenerate point encountered at the edge of the stopband in a periodic structure, which leads to field enhancement and high-Q resonances. The choice of SIW technology can lead to the use of the DBE concept in microwave and mm-wave integrated circuits, given the easy fabrication, low profile and low-cost features of this technology. Applications of this concept will be oscillators having low threshold currents and being robust to external loading, and sensors with high directivity and sensitivity. Conditions for the design of a unit cell providing a DBE point are given after an analysis of several kinds of unit cells. Based on these guidelines, several SIWs-DBE designs are presented. The influence of losses, of geometrical perturbations, and of truncation are considered. Typical DBE characteristics, such as field enhancement and a steep increase of Q factor and group delay vs. the number of cells in a truncated resonator are observed in lossless and lossy situations. Feeding transitions are designed to feed the SIWs-DBE lines and to perform measurements which fully validate the theoretical analyses. Finally, the design procedure is also applied to a multilayer integrated waveguide, particularly suitable for integrated millimeter-wave applications, showing the versatility of the proposed methodology
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Pais, Correia Ana Monica. "Biofilm-like extracellular viral assemblies mediate HTLV-1 (human T cell leukemia virus type-1) cell-to-cell transmission at virological synapses." Paris 7, 2009. http://www.theses.fr/2009PA077233.
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Près de 20 millions d'individus sont infectés par HTLV-1 (human T cell leukemia virus type-1). La plupart des patients n'ont aucun symptôme, seulement 5-10% d'entre eux développeront des maladies associées à l'infection virale. La particularité d'HTLV-1 est de se transmettre par des contacts cellulaires désignés « synapses virologiques », qui partagent certaines caractéristiques avec les synapses immunologiques. Ce projet a permis de mieux comprendre le processus de transmission cellule à cellule et introduit un nouveau concept de transmission virale par des « biofilms viraux ». Contrairement à ce qui avait été suggéré, nous démontrons qu'HTLV-1 s'accumule à la surface des cellules infectées, dans des structures composées de matrice extracellulaire (HSPG agrine, collagène) et de molécules de type « linker » (galectine, tetherine). Ces structures facilitent l'adhésion et la cohésion du virus et sont essentielles pour une transmission virale efficace, car leur détachement diminue fortement l'infection de cellules cibles («80%). Les structures que nous avons décrites concentrent et protègent le virus, permettent son stockage et aident à sa propagation. Ces caractéristiques ressemblent à celles des biofilms bactériens ou des champignons. Ainsi, nous proposons le nom « biofilm viral» pour désigner ce nouveau processus de transmission virale<br>Approximately 20 million people are infected by HTLV-1 (human T cell leukemia virus type-1). Although the majority of infected individuals remain asymptomatic, around 10% will develop HTLV-1-associated disease. HTLV-1 has been described to efficiently propagate through cell-cell contacts. Designated as virological synapses, these cellular contacts exhibit some of the characteristics of immunological synapses. This project has allowed a better comprehension of how HTLV-1 propagates from cell-to-cell and proposes a completely novel concept of virus transmission through 'viral biofilms'. Contrary to what was previously suggested we have shown that HTLV-1 is accumulated at the surface of infected cells, in extracellular viral assemblies. Viral assemblies are composed of extracellular matrix (HSPG agrin, collagen) and linker molecules (galectin, tetherin) that provide the adhesion and cohesion forces needed to maintain viruses at the cell surface. More importantly, we have shown that HTLV- 1 viral assemblies contribute to the majority of virus cell-cell transmission since their removal significantly inhibits infection (« 80%). Viral assemblies, store, concentrate, disseminate and protect the virus. These characteristics recapitulate most of the features of bacterial or fungal biofilms. Therefore, we propose the use of the term 'viral biofilm' to designate this new mode of cell-to-cell virus spread
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Do, Xuan Khoi͏̈. "Modélisation d'une ligne de transmission d'énergie pour l'analyse des transitoires électromagnétiques : réalisation par équation d'état de la matrice de fonction de transfert impédance." Grenoble INPG, 1991. http://www.theses.fr/1991INPG0114.
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La modélisation d'une ligne de transmission d'énergie électrique en régimes transitoires électromagnétiques par une représentation d'état permet de profiter de divers outils de la théorie des systèmes dynamiques et des équations différentielles. Nous avons considéré cette approche en l'appliquant à des matrices de fonctions de transfert (MFT) rationalisées : la MFT de propagation A et la MFT impédance et sur sa représentation d'état. L'utilisation de la MFT Z est plus simple que celle de la MFT A et plus performante numériquement que celle par MFT admittance Y. Un schéma d'intégration explicite est employé pour avoir la possibilité d'un calcul découplé entre les extrémités d'une ligne. La stabilité de l'intégration numérique est améliorée par une méthode de prédiction-correction. Pour compléter l'algorithme de la modélisation d'une ligne, une méthode de calcul de la matrice de transformation modale dépendant de la fréquence a été mise au point. Une première série de simulations numériques a permis de valider le modèle
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Oubaha, Khalid. "Transport micro-ondes dans un milieu complexe vers une communication sans fil à base des circuits intégrés." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4061.
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De nos jours, nous assistons à une forte évolution des systèmes modernes de la communication sans fil, exploitant des fréquences très élevées, dans la bande des fréquences micro-ondes. De ce fait, pour éviter des architectures compactes des systèmes électroniques composant ces systèmes modernes, apparaît la nécessité d'envisager la communication sans fil entre les circuits imprimés intégrés aux systèmes électroniques.Les principaux problèmes rencontrés dans ces systèmes concernent l'effet de l'environnement sur la communication sans fil et la protection contre les effets indésirables. Cela exige de nouvelles techniques de simulation et de modélisation du champ EM dans ces environnements complexes, pour une prédiction de leurs comportements.Avec les expériences effectuées dans le domaine des micro-ondes, ces techniques seront possibles en se basant sur la théorie des matrices aléatoires (TMA), bien adaptée dans ces situations de milieu complexe.Les travaux effectués au cours de cette thèse présentent :Dans un premier temps, l'illustration d'un exemple d'une telle situation où tous les ingrédients sont présents (circuit imprimé, lignes de transmissions et cavité). Nous avons présenté une étude expérimentale, qui met en évidence l'effet de l'environnement partiellement réverbérant sur la diaphonie entre les lignes imprimées, de sorte que leurs courants ne soient pas négligés et doivent être pris en compte, pour la conception appropriée de circuit imprimé, garantissant leur fonctionnement.Dans un second temps, dans le but d'étudier et d'analyser statistiquement le comportement de la transmission à l'intérieur d'un milieu complexe, nous avons réalisé une chambre réverbérante chaotique (CRC), qui satisfait aux critères statistiques fixés par la norme internationale. Le critère principal exige d'avoir une uniformité et isotropie statistique du champ à l'intérieur de la CRC et que les composantes du champ suivent une distribution gaussienne bivariée. Dans la communauté de la Compatibilité d'Électromagnétique (CEM), on parle de l'hypothèse de Hill, typiquement réalisée quand le recouvrement modal est grand. Nous avons étudié expérimentalement plusieurs statistiques de la réponse de la CRC et les effets du régime de fort recouvrement modal sur les distributions de la réflexion et la transmission, puis nous les avons comparées aux prédictions numériques prévues par la TMA.Nous avons également vérifié la relation de l'espacement moyen entre les maxima de transmission prédite par Schroeder et Kuttruff pour un régime fort recouvrement modal, dans les salles acoustiques.Dans un troisième temps, nous avons développé une nouvelle méthode pour l'estimation de nombre d'échantillons non corrélés (NIS) dans une CRC. Puis nous avons suggéré une perspective pour l'estimation de NIS, basée sur l'échelle caractéristique de la dynamique des maxima en fonction de l'angle de brasseur<br>Nowadays, modern wireless communication systems that are operating at high frequencies in the microwave band, are massively emerging. To avoid compact architectures of electronic systems, we explore wireless communication between printed circuits integrated into the electronic systems. Several problems encountered in these systems are related to the effect of the environment on wireless communication and the protection against adverse effects. This requires new electromagnetic simulation techniques to describe the field and the system response in these environments. Along with the microwave experiments, random matrix theory (RMT) enables to theoretically study wireless communication in complex environment.This manuscrit is diveded in three main topics:On the one hand, an illustration of the situation where all the ingredients are implemented namely, a Printed Circuit Board (PCB) with transmission lines inside a cavity. I present an experimental study, which highlights the effect of the partially reverberating environment on the crosstalk of two printed lines, as well as the currents on these lines. The latter should be taken into account to guarantee the proper functioning of the PCB.On the other hand, a chaotic reverberating chamber (CRC) was designed to statistically analyze the behavior of the transmission inside a complex environment. The international standard fix several statistical criteria with which the RC have to comply. Fulfilling all criteria guarantees that the field inside the cavity is isotropic and the field components follow a bivariate Gaussian distribution. In the electromagnetic community, this is the so-called Hill’s hypothesis. This hypothesis is typically realized when the resonance overlap is large. I have experimentally studied several statistic properties of the electromagnetic response in a CRC. The effects of the modal overlap on the reflection and the transmission distributions have been analyzed. In addition to this, we have compared the experimental distributions to numerical predictions based on Random Matrix Theory. I also verified the relation between the mean frequency spacing of the maxima and the average decay rate of the cavity predicted by Schroeder and Kuttruff for a high modal overlap in acoustic rooms.Finaly, we have developed a new method to estimate the number of uncorrelated samples (NIS) in a CRC. We have suggested a perspective for NIS estimation based on the characteristic scale of maxima dynamics as a function of the stirrer angle
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Rossi, Filippo Vincenzo. "Graphics hardware accelerated transmission line matrix procedures." Thesis, 2010. http://hdl.handle.net/1828/2941.
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The past decade has seen a transition of Graphics Processing Units (GPUs) from special purpose graphics processors, to general purpose computational accelerators. GPUs have been investigated to utilize their highly parallel architecture to accelerate the computation of the Transmission Line Matrix (TLM) methods in two and three dimensions. The design utilizes two GPU programming languages, Compute Unified Device Architecture (CUDA) and Open Computing Language (OpenCL), to code the TLM methods for NVIDIA GPUs. The GPU accelerated two-dimensional shunt node TLM method (2D-TLM) achieves 340 million nodes per second (MNodes/sec) of performance which is 25 times faster than a commercially available 2D-TLM solver. Initial attempts to adapt the three-dimensional Symmetrical Condensed Node (3D-SCN) TLM method resulted in a peak performance of 47 MNodes/sec or7 times in speed-up. Further efforts to improve the 3D-SCN TLM algorithm, as well as investigating advanced GPU optimization strategies resulted in performances accelerated to 530 MNodes/sec, or 120 times speed-up compared to a commercially available 3D-SCN TLM solver.
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Lorenz, Petr [Verfasser]. "Transmission line matrix - multipole expansion method / Petr Lorenz." 2007. http://d-nb.info/988204495/34.
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Lukashevich, Dzianis [Verfasser]. "Model order reduction (MOR) in transmission line matrix (TLM) method / Dzianis Lukashevich." 2005. http://d-nb.info/977594025/34.
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