Dissertations / Theses: 'B-mode'

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Legg, Stephen. "Multi-mode receiver systems for cosmic microwave background B-mode polarisation experiments." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/multimode-receiver-systems-for-cosmic-microwave-background-bmode-polarisation-experiments(11399beb-9f3d-455b-b236-7d612ab1a00b).html.

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A measurement of the primordial B-mode polarisation of the Cosmic Microwave Background would provide direct evidence of inflation in the early universe. The extremely weak nature of the B-mode signal necessitates an instrument with a high sensitivity and precise control over systematic effects. Multi-mode antenna feed horns offer higher sensitivity than their single-mode counterparts, however their behaviour is much more complex. The Short Wavelength Instrument for the Polarisation Explorer (SWIPE) onboard the Large Scale Polarisation Explorer (LSPE) is one instrument planning to implement multi-mode feed horns. SWIPE will attempt to detect the primordial B-mode at large angular scales, measuring the sky in three bands at 140, 220 and 240 GHz. A single on-axis High-Density PolyEthylene (HDPE) lens and polarisation-splitting wire grid combine to focus the radiation from the sky onto two focal planes of multi-mode horns feeding bolometric detectors. A large diameter rotating metal-mesh half-wave plate allows both polarisations to be measured by the same pixel, therefore bypassing many detector systematics. Simulations are performed to predict the sky beam for two key pixels: closest to and furthest from the centre of the focal plane. For the 140 GHz channel the cross-polarisation is predicted, and the optimum location at which to place the telescopeâs focus behind the horn aperture to maximise gain and optimise beam shape is investigated. A measurement of the multi-mode horn is performed using a room-temperature bolometer. An investigation is also conducted to assess to what extent the same measurements can be performed using a coherent measurement system such as a vector network analyser. A working coherent measurement technique is devised, however it is limited to horns carrying only the first 3 modes.

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2

James, Phillip Richard. "Probing the mode of action of amphotericin B." Thesis, University of Leicester, 1996. http://hdl.handle.net/2381/33755.

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The antifungal agent amphotericin B is the treatment of choice for many topical and leep-seated systemic fungal infections, despite its potent human toxicity. The mode of action is believed to involve the formation of ion channels across the plasma membrane of the fungal cells, leading to the loss of essential electrolytes such as potassium ions. Evidence suggests that the channels arise as a result of complexation of the antifungal agent with membrane steroids, both in fungal cells (ergosterol) and human cells (cholesterol), the latter being responsible for the toxicity of the drug. In order to span the plasma membrane, to create a continuous channel, such channels would be expected to involve pairs of steroid molecules laying end to end along the radial axis of the cell. To examine this proposed mode of action, a series of tail-to-tail linked dimeric steroid analogues, capable of spanning the entire membrane bilayer, have been prepared, in a seven step synthesis from stigmasterol. These have been incorporated into artificial membranes (liposomes), and their ability to participate in transmembrane pore assembly, in the presence of amphotericin B, have been compared with that of cholesterol, using an assay based on sodium NMR, which measures efflux of sodium ions from the volume encapsulated by the membrane. The dimers did not support significant ion efflux. Furthermore, the proposed transmembrane channel containing cholesterol has been visualised at the molecular level by means of a computerised molecular modelling package, and compared with models of channels containing the dimers. The inability of the steroid dimers to promote efflux from liposomes, coupled with the modeling studies has led to a revised proposal for the mode of action.

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Golemati, Spiretta. "Motion analysis of atherosclerotic plaque from b-mode ultrasound." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396015.

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Freethy, Simon. "Synthetic aperture imaging of B-X-O mode conversion." Thesis, University of York, 2012. http://etheses.whiterose.ac.uk/2352/.

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The conversion of thermally-born electrostatic waves in tokamak plasmas has the potential to be a powerful diagnostic for tokamak edge physics. Analytic theory and full wave modelling both conclude that analysis of emission in the microwave region carries with it information on the magnetic field in spatially localised areas which depend on density and frequency. Knowing these quantities and the 3D (2D + frequency) microwave emission pattern, it is in theory possible to calculate the current density which is vital to the understanding of the plasma pedestal. Motivated by a pilot experiment carried out on the Mega Ampere Spherical Tokamak (MAST), a novel microwave imaging device has been developed to obtain the first images of mode conversion in a Tokamak and to prove the principle of the synthetic aperture imaging technique on Tokamak devices. Here the design and calibration of the Synthetic Aperture Microwave Imaging (SAMI) radiometer is described, as well as the presentation and comparison of some of the first images of mode conversion with full wave simulations.

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Crombie, Pinar. "Fundamental studies on contrast resolution of ultrasound B-mode images." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ45685.pdf.

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Jochum, John R. (John Richard) 1976. "Encripted mode select ADS-B for tactical military situational awareness." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86721.

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Ren, Jing. "From RF signals to B-mode Images Using Deep Learning." Thesis, KTH, Medicinteknik och hälsosystem, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235061.

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Ultrasound imaging is a safe and popular imaging technique that relies on received radio frequency (RF) echos to show the internal organs and tissue. B-mode (Brightness mode) is the typical mode of ultrasound images generated from RF signals. In practice, the real processing algorithms from RF signals to B-mode images in ultrasound machines are kept confidential by the manufacturers. The thesis aims to estimate the process and reproduce the same results as the Ultrasonix One ultrasound machine does using deep learning. 11 scalar parameters including global gain, time-gain-compensation (TGC1-8), dynamic range and reject affect the transformation from RF signals to B-mode images in the machine. Data generation strategy was proposed. Two network architectures adapted from U-Net and Tiramisu Net were investigated and compared. Results show that a deep learning network is able to translate RF signals to B-mode images with respect to the controlling parameters. The best performance is achieved by adapted U-Net that reduces per pixel error to 1.325%. The trained model can be used to generate images for other experiments.

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Stolpovskiy, Mikhail. "Development of the B-mode measurements pipeline for QUBIC experiment." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC284/document.

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QUBIC est une expérience au sol en cours de construction dont le but est de mesurer les modes-B primordiaux du fond diffus cosmologique en utilisant la technique innovante de l’interférométrie bolométrique. Grace à la fusion entre interférométrie et imagerie,QUBIC a une très bonne sensibilité et un excellent contrôle des effets systématiques instrumentaux. De plus, du fait de la dépendance en fréquence du lobe synthétique,QUBIC peut être utilisé comme un spectre-imageur. Ces points pris en compte, la sensibilité globale de QUBIC au rapport tenseur/scalaire est 0.012. L’objectif de cette thèse est de d´écrire le code d’analyse de données de QUBIC, depuis la fabrication de cartes`a partir des données temporelle jusqu’`a la séparation de composantes astrophysique, l’estimation du spectre de puissance angulaire et celle des paramètres cosmologiques.Les aspects essentiels de ce travail sont les suivants: la fabrication de carte qui est très inhabituelle vis à vis des autres projets du domaine et le développement de la stratégie de couverture du ciel pour QUBIC
QUBIC is a ground-based experiment aiming to measure the primordial B-modes, currently under construction, that uses the novel bolometric interferometry technique. Thanks to the fusion nature of QUBIC, it has very good sensitivity and excellent control of systematics. Moreover, the fact that the synthesized beam depends on the wavelength allows us to treat QUBIC as a spectro-polarimeter. These factors together give sensitivity on tensor-to-scalar ratio r 0.012. The goal of this thesis is to describe the pipeline of data analysis for QUBIC, from map-making of CMB from raw time-ordered data, through component separation and power spectra estimation to cosmological parameter estimation. The main accents of this work are: map-making, which is very unusual in comparison with other experiments in the field, and the development of scanning strategy for QUBIC

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Fredriksson, Daniel, and Anders Schweitz. "Technical Verification and Validation of TIS-B using VDL Mode 4." Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2393.

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This report is a technical verification and validation of Traffic Information Service Broadcast (TIS-B) using the data link VDL Mode 4.

The main objective of the report is to examine the usefulness of TIS-B considering the results from tests performed in the Stockholm Terminal Area and for the Advanced Surface Movement Guidance and Control System (A-SMGCS) at Arlanda airport. The results are compared with the requirements that have been set by the standardisation organisations ICAO, RTCA, Eurocontrol and Eurocae. TIS-B is however such a new concept, so most of the operational requirements have not yet been defined.

The process for performing the evaluation of TIS-B involves three stages:

· Study the requirements on TIS-B, ADS-B, radar and A-SMGCS.

· Verify TIS-B by performing tests at Arlanda airport.

· Validate the test results through analysis.

A theoretical study of slot allocation optimisation is performed to decide how the slot allocation is to be implemented.

The report includes a Functional Hazard Analysis (FHA). The FHA is done to see if the applications for TIS-B are ready for implementation or if more hazard preventing actions has to be taken, before any operational actions can be performed.

The report also involves a theoretical introduction to Air Traffic Management (ATM), Surveillance techniques and TIS-B.

All parts included in the report results in conclusions and recommendations regarding the TIS-B service.

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Galén, Steffi [Verfasser]. "B- und M-Mode-Sonographie der Zunge während des Schluckens / Steffi Galén." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2009. http://d-nb.info/1023785013/34.

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11

Cunningham, Ryan. "The application of b-mode ultrasonography for analysis of human skeletal muscle." Thesis, Manchester Metropolitan University, 2015. http://e-space.mmu.ac.uk/582279/.

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Skeletal muscles control the joints of the skeletal system and they allow human movement and interaction with the environment. They are vital for stability in balance, walking and running, and many other skilled motor tasks. To understand how muscles operate in general and specific situations there are a variety of tools at the disposal of research scientists and clinicians for analysing muscle function. Strain gauges for example allow the quantification of forces exerted during joint rotation. However, skeletal muscles are multilayer systems and often different muscles are responsible for the overall force generated during joint rotation. Therefore, strain gauges do not reveal the extent of the contribution of individual muscles during muscle function. The most widely-used and accepted muscle analysis tool is electromyography (EMG), which can measure the activation level of individual muscles by measuring the electrical potential propagating through muscle resulting from local activations of motor units. However, EMG does not linearly relate to any real physical forces, meaning that without prior knowledge of the force exertion on the level of the muscle, force cannot be estimated. EMG can measure superficial layers of muscle non-invasively by attaching surface electrodes (surface EMG) to the skin over the belly of the muscle. To measure the activity of individual muscle beneath the superficial muscle, a needle or thin-wire electrode must be inserted through the skin and into the muscle volume (intramuscular EMG), which is invasive and not practical in many situations. Furthermore, intramuscular EMG can only provide measurement of a very small volume (< 1mm³) which can have varying amounts of active motor units. Ultrasonography is a powerful cost-effective non-invasive imaging technology which allows real-time observation of cross-sections of multiple layers of dynamic skeletal muscle. Recent advances in automated skeletal muscle ultrasound analysis techniques, and advances in image processing techniques make ultrasound a valuable line of investigation for analysis of dynamic skeletal muscle. This aim of this thesis is to study and develop advanced image analysis techniques applicable to the analysis of dynamic skeletal muscle. The broader aim is to understand the capacity/limits of ultrasound as a skeletal muscle analysis tool. The ideas presented within offer new approaches to modelling complex muscle architecture and function via ultrasound. Tools have also been developed here that will contribute to, and promote ultrasound skeletal muscle analysis as a new and emerging technology which may be used by clinicians and research scientists to develop our understanding of skeletal muscle function. The main findings of this thesis are that automated segmentation of architecturally simple and complex skeletal muscle groups is possible and accurate, and that information about joint angles and muscle activity/force can be automatically extracted directly from ultrasound images without the explicit knowledge of how to extract it. The techniques used offer new possibilities for non-invasive information extraction from complex muscle groups such as the muscles in the human posterior neck.

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Schoenaers, Caroline. "Mode identification in slowly pulsating subdwarf-B stars from line-profile variations." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491972.

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In previous attempts to perform seismic modelling of pulsating subdwarf-B stars, various mode identification techniques have been used, with less success than in pulsating Main Sequence stars. In this work I investigate a method so far neglected in sdB stars, that is, mode identification from the line-profile variations caused by stellar pulsation. I present the first detailed spectrum synthesis of pulsating subdwarf-B stars, taking into account variations, due to non-radial pulsations, in radial velocity, surface temperature, surface gravity and surface normal. Time-series of synthetic spectra demonstrate line-profile variations are to be expected in pulsating subdwarf-B stars. I then present the 'synthetic moment' method, an original spectroscopic mode identification method I designed, and test it extensively on synthetic line-profile variations representative of those observed in slowly pulsating subdwarf-B stars. The 'synthetic moment' method is applied to spectroscopic data of slowly pulsating subdwarf-B stars HD 4539, EC 21324-1346 and PG 1627+017 I obtained at the South African Astronomical Observatory. For each of these stars I identify several pulsation modes, which in turn allows me to select their possible evolutionary stages. My pioneering work on spectroscopic mode identification in slowly pulsating subdwarf-B star sets the stage for a thorough analysis of all known sdB pulsators, thereby making for a better understanding of this late stage of stellar evolution.

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O'Brien, Brendan Joseph. "Search for the Higgs boson via the H → b¯b decay mode, in the boosted regime on the ATLAS experiment." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/15936.

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This thesis presents details of the search for the Standard Model Higgs boson, in the low mass region (100 ≤ MH < 150 GeV), with the ATLAS detector at CERN. In this range, a Higgs boson may be produced in association with a W or Z-boson and decay predominantly to two b-quarks (H → b¯b). Specifically events having large Higgs boson transverse momentum (pT > 200 GeV) and large recoiling W- boson transverse momentum (pT > 200 GeV) are considered as a means to reduce the contribution from background processes. In this high pT (boosted) regime, novel jet-substructure techniques are applied to the reconstructed jets resulting from the Higgs boson decay. In order to use these jet-substructure techniques, b-tagging efficiency scale factors in the jet-substructure regime have also been derived for the first time. Details of their derivation are presented for many b- tagging algorithms, with 14.3 fb¯¹ of ATLAS proton-proton collision data in 2012 at √s = 8 TeV. These, and their associated systematic uncertainties, are then applied to the Higgs boson search. No significant measurement of Higgs boson production was made, based on 20.4 fb¯¹ of ATLAS proton-proton collision data in 2012 at √s = 8 TeV. For a Higgs boson mass of 125 GeV, an exclusion limit of 6.12 x σSM was found at the 95% confidence level, and a signal strength of 0:93 ± 2:63 was measured, consistent with both background-only and signal (Standard Model Higgs boson) plus background hypotheses.

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14

Holzinger, Ingelore. "Sonomorphologische Charakterisierung peripherer pulmonaler Konsolidierungen Evaluierung mit B-Mode-Thoraxsonographie und farbkodierter Dopplersonographie /." [S.l.] : [s.n.], 2003. http://archiv.ub.uni-marburg.de/diss/z2003/0554/.

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Eriksson, Matts, and Jonas Lundmark. "Technical Verification and Validation of ADS-B/VDL Mode 4 for A-SMGCS." Thesis, Linköping University, Department of Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1417.

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This report is a technical verification and validation of ADS-B (Automatic Dependent Surveillance – Broadcast) over VDL Mode 4 (Very High Frequency Data Link Mode 4) for the use in the surveillance element of an A-SMGCS (Advanced Surface Movement Guidance and Control System).

The main objective of this report is to examine if ADS-B/VDL Mode 4 fulfils the technical requirements for an implementation at Arlanda airport, Stockholm Sweden. The report also includes a FMECA (Failure Mode, Effects and Criticality Analysis), a theoretical background and methods for monitoring.

The process of making this report can be divided into three phases:

1. Preliminary Study. In this phase the requirements were examined and structured.

2. Verification. In this phase the system performance has been verified both theoretically and by several tests at Arlanda Airport. Simulation results have also been used.

3. Validation and documentation. The tests and verifications that were performed in phase 2 were validated in the third phase of the project. The final project document was also written in this phase.

The main conclusion from this analysis is that ADS-B/VDL Mode 4 is well suited for surveillance. ADS-B/VDL Mode 4 has the possibility to fulfil all considered requirements, apart from detecting all obstacles. But if all the requirements are going to be fulfilled depends both on the implementation and the operational environment.

The results from this verification and validation should be used as the technical subset in a future safety case, both in Sweden and internationally.

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Coleman, Declan Paul. "Characterisation of carotid atherosclerotic plaque composition in vivo using 3D B-mode ultrasound." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/55703/.

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Embolisation from carotid atherosclerotic plaque is a major cause of ischaemic stroke. Studies have shown that it is not only the degree of narrowing of the carotid artery but also the constituents of the plaques which are important factors in determining whether a plaque ruptures and embolises. A reliable and repeatable method has been developed to acquire in vivo data of carotid plaques using 3D B-mode ultrasound. An artificial neural network was enabled using MATLAB software programs to characterise each of the plaque constituents into one of five classes based on statistical and textural parameters of the B-mode images. Comparison of the method with histology processing post surgery found that characterisation of plaque constituents in vivo is not readily achievable. The method, however, was found to be repeatable in serial scans and was used to monitor the effect of two different lipid lowering drug treatments over a 12 week period. Two patients who underwent LDL apheresis treatment showed reduction in softer class types and increases in the harder class types along with reductions in the overall plaque volumes. Nine patients underwent statin treatment with changes found in 4 of the 9 patients over the period of the study. There are several possible reasons why changes were seen in the apheresis group and only in some of the statin group. The apheresis treatment is more aggressive than the statin treatment, the time period of the study was relatively short and changes in the tissue types are dependant on the initial constituents of the plaque.

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COLSON, DIDIER. "Mesure de l'epaisseur intima/media par echographie mode b : etude de la reproductibilite." Toulouse 3, 1993. http://www.theses.fr/1993TOU31132.

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Xu, Kele. "Visualisation tridimensionnelle de la langue basée sur des séquences d'image échographique en mode-B." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066498/document.

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Une interface vocale silencieuse (SSI) est un système permettant une communication vocale à partir d’un signal non audible. Un tel système emploie des capteurs qui enregistrent des données non-acoustiques, pour la reconnaissance et la synthèse vocales. Cependant, l’extraction des caractéristiques articulatoires robustes à partir de ces signaux reste un défi. La langue est une composante majeure de l'appareil vocal, et l'articulateur le plus important dans la production de parole. Une simulation réaliste du mouvement de la langue en 3D peut fournir une représentation visuelle directe et efficace de la production de parole. Cette représentation pourrait à son tour être utilisée pour améliorer les performances de reconnaissance vocale d'un SSI, ou servir d'outil dans le cadre de recherches sur la production de parole et de l'étude des troubles de l'articulation. Dans cette thèse, nous explorons un nouveau cadre de visualisation en trois dimensions de la langue, qui combine l'imagerie échographique 2D et une technique de modélisation tridimensionnelle fondée sur la physique. Tout d'abord, différentes approches sont utilisées pour suivre le mouvement de la langue dans les séquences d'images échographiques, qui peuvent être regroupées en deux principaux types de méthodes : le suivi de la granularité et le suivi de contour. Les méthodes de suivi du chatoiement (speckle tracking) comprennent le recalage de déformations (deformation registration), le flux optique, et la méthode de transformation de caractéristiques visuelles invariante à l'échelle (Scale-invariant feature transform, ou SIFT). En outre, une méthode de suivi réinitialisation basée sur l'image est proposée afin d'améliorer la robustesse du suivi du chatoiement. En comparaison avec le suivi de chatoiement, l'extraction du contour de la surface de la langue à partir d'images échographiques présente des performances supérieures et une meilleure robustesse. Dans cette thèse, un nouvel algorithme de suivi de contour est présenté pour des séquences d'images échographiques de la langue. Cet algorithme permet de suivre le mouvement des contours de la langue sur de longues durées avec une bonne robustesse. Pour résoudre la difficulté causée par les segments manquants dus au bruit ou celle causée par la surface mi-sagittale de la langue qui est parallèle à la direction de propagation de l'onde ultrasonore, nous proposons d’utiliser des contours actifs avec une contrainte de similitude de contour, qui fournissent des informations a priori sur la forme de la langue. Des expériences sur des données synthétiques et sur des images réelles acquises sur différents sujets à la cadence de 60 images par seconde montrent que la méthode proposée donne un bon contour de suivi pour ultrasons des séquences d'images, même sur des durées de quelques minutes. Cette technique peut par conséquent être utile dans des applications telles que la reconnaissance vocale où de très longues séquences doivent être analysées dans leur intégralité…
A silent speech interface (SSI) is a system to enable speech communication with non-audible signal, that employs sensors to capture non-acoustic features for speech recognition and synthesis. Extracting robust articulatory features from such signals, however, remains a challenge. As the tongue is a major component of the vocal tract, and the most important articulator during speech production, a realistic simulation of tongue motion in 3D can provide a direct, effective visual representation of speech production. This representation could in turn be used to improve the performance of speech recognition of an SSI, or serve as a tool for speech production research and the study of articulation disorders. In this thesis, we explore a novel 3D tongue visualization framework, which combines the 2D ultrasound imaging and 3D physics-based modeling technique. Firstly, different approaches are employed to follow the motion of the tongue in the ultrasound image sequences, which can be divided into two main types of methods: speckle tracking and contour tracking. The methods to track speckles include deformation registration, optical-flow, and local invariant features-based method. Moreover, an image-based tracking re-initialization method is proposed to improve the robustness of speckle tracking. Compared to speckle tracking, the extraction of the contour of the tongue surface from ultrasound images exhibits superior performance and robustness. In this thesis, a novel contour-tracking algorithm is presented for ultrasound tongue image sequences, which can follow the motion of tongue contours over long durations with good robustness. To cope with missing segments caused by noise, or by the tongue midsagittal surface being parallel to the direction of ultrasound wave propagation, active contours with a contour-similarity constraint are introduced, which can be used to provide “prior” shape information. Experiments on synthetic data and on real 60 frame per second data from different subjects demonstrate that the proposed method gives good contour tracking for ultrasound image sequences even over durations of minutes, which can be useful in applications such as speech recognition where very long sequences must be analyzed in their entirety…

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Shi, Xun [Verfasser]. "Third-order Cosmic Shear Statistics: Covariance, Nulling, and E/B-mode decomposition / Xun Shi." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1043910859/34.

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Derrick, Peter Michael. "An investigation into the mode of action of the herbicide M and B 39279." Thesis, Nottingham Trent University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327791.

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Berthomier, Thibaud. "Identification et caractérisation du thrombus veineux par imagerie échographique mode B couplée à l’élastographie." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2018. http://www.theses.fr/2018ENTA0007/document.

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La maladie veineuse thromboembolique (MVTE) est un problème de santé publique (plus de 100000 cas par an en France). Elle regroupe deux entités cliniques : la thrombose veineuse profonde (TVP) des membres inférieurs et l’embolie pulmonaire (EP). La TVP correspond à la formation inadaptée d’un thrombus veineux (appelé aussi caillot sanguin) dans les veines profondes (poplitées, fémorales, iliaques). Un thrombus est principalement constitué de globules rouges et de plaquettes dans un réseau de fibrine. La complication majeure d’une TVP est la survenue d’une EP, c’est-à-dire que le thrombus s’est détaché de la paroi veineuse, ou s’est fragmenté, et est entraîné par la circulation sanguine jusqu’à une artère pulmonaire. Cette complication a un taux de mortalité assez élevée autour de 10000 à 20000 cas mortels par an en France. La survenue d’une TVP est multifactorielle associant des facteurs génétiques et acquis pouvant être répartis en trois catégories : la stase veineuse, l’altération de la paroi d’une veine et une hypercoagulabilité. En analysant la structure du thrombus, notre projet vise à identifier le facteur principal responsable de la TVP et à évaluer le risque d’EP. Pour caractériser sa structure, nous disposons de deux modes d’imagerie acoustique : l’échographie et l’élastographie (carte de dureté). Nous proposons d’extraire des descripteurs de ces images acoustiques par deux approches, l’une basée sur les ondelettes (le scattering operator) et l’autre sur les statistiques d’ordre supérieur (les multicorrélations). Ces descripteurs sont ensuite analysées par diverses techniques de classification (analyse en composantes principales, k-moyennes, classification spectrale) pour retrouver la cause principale des TVP ou la présence d’EP
Venous thromboembolism (VTE) is an important public health issue (over 100000 individuals in France per year). VTE is a combination of a deep venous thrombosis (DVT) and a pulmonary embolism (PE). DVT is an inappropriate formation of a thrombus (also called blood clot) in one of the deep veins of the body, usually in the leg (popliteal, femoral, iliac). There are mainly three components in a thrombus: platelets, red blood cells and a mesh of fibrins. The main complication of a DVT is a pulmonary embolism (PE) which occurs when a thrombus breaks loose and travels to the lungs. PE affects an estimated 10000 - 20 000 individuals just in France per year. Three physiopathological mechanisms cancontribute, isolated or combined, to the development of a DVT: venous stasis, endothelial injury and hypercoagulability. Our project is aiming to relate the thrombus structure, its main triggering factor and the risk of a PE. To characterize the thrombus structure, we are collecting ultrasonography (echogenicity) and elastography (stiffness) of human thrombus. We propose to extract features from these to kind of ultrasound images using two approaches: one basedon wavelets (the scattering operator) and another based on high order statistics (multicorrelations). Then, the obtained features are analysed using several classification technics (principal component analysis, k-means, spectral clustering) to find the main cause of the DVT or the presence of PE

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Davies, Jevon Raymond. "Continuous wave mode locking for the determination of the acoustic nonlinearity parameter B/A." Doctoral thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5269.

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Bibliography: p. 140-148.
The acoustic nonlinearity parameter B/A of the nonlinearity of the equation of state for a fluid. Its significance can be found in numerous fields including shockwaves, bio-chemistry and medicine. Recent studies in the field of biomedical ultrasound have necessitated a simple and accurate means of measuring B/A in vitro.

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Mendonça, Matheus Rodrigues de. "Análise de modos normais dos movimentos conformacionais em proteínas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-18042016-104716/.

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A caracterização das flutuações dos resíduos da proteína em torno do seu estado nativo é essencial para estudar mudanças conformacionais, interação proteína-proteína e interação proteína-ligante. Tal caracterização pode ser capturada pelo modelo de rede gaussiana (GNM). Este modelo tem sido modificado e novas propostas têm surgido nos últimos anos. Nesta Tese, apresentamos um estudo sobre como melhorar o GNM e exploramos o seu desempenho em predizer os fatores-B experimentais. Modelos de redes elásticas são construídos a partir das coordenadas experimentais dos levando em consideração pares de átomos de C? distantes entre si até um dado raio de corte Rc . Estes modelos descrevem as interações entre os atómos por molas com a mesma constante de força. Desenvolvemos um método baseado em simulações numéricas com um campo de forças simplificado para atribuir pesos a estas constantes de mola. Este método considera o tempo em que dois átomos de C? permanecem conectados na rede durante o desenovelamento parcial, estabelecendo assim uma forma de medir a intensidade de cada ligação. Examinamos dois diferentes campos de forças simplificados e exploramos o cálculo desses pesos a partir do desenovelamento das estruturas nativas. Nós comparamos o seu desempenho na predição dos fatores-B com outros modelos de rede elástica. Avaliamos tal desempenho utilizando o coeficiente de correlação entre os fatores-B preditos e experimentais. Mostramos como o nosso modelo pode descrever melhor os fatores-B
The characterization of the fluctuations in protein residues around its native state is essential to study conformational changes, protein binding interaction and protein-protein interaction. Such characterization can be captured by simple elastic network models as the Gaussian Network Model (GNM). This model has been modified and new proposals have emerged in recent years. In this Thesis we propose an extended version of GNM, namely wGNM. Elastic network models are built on the experimental C? coordinates,and they only take the pairs of C? atoms within a given cutoff distance Rc into account. These models describe the interactions by elastic springs with the same force constant to predicted the experimental B-factors, providing insights into the structure-function properties of proteins. We have developed a method based on numerical simulations with a simple coarse-grained force field, to attribute weights to these spring constants. This method considers the time that two C? atoms remain connected in the network during partial unfolding, establishing a means of measuring the strength of each link. We examined two different coarse-grained force fields and explored the computation of these weights by unfolding native structures. We compare the B-factors predicted by different elastic network models with the experimental ones employing the correlation coefficient between these two quantities. We show that wGNM performs better and consequently provides better evaluation of the B-factors

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Dragunova, Yulia, and Joakim Anderberg. "Utvärdering av en billig ultraljudsmaskin med avseende på bildkvalitet och temperaturökning." Thesis, KTH, Medicinteknik och hälsosystem, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297584.

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Ultraljudsdiagnostik baseras på propagering av mekaniska vågor och används för att avbilda tvärsnitt av kroppen i realtid. Prestandan, med avseende på kontrast, upplösning och måttmätningar, av CONTEC CMS600B-3, en relativ billig maskin är av intresse. Hur volymen av en fantom, dess ytarea och frekvens på utskickade vågor påverkar uppvärmningen av vävnader är även av intresse. Det undersöktes med ultraljudsmaskinerna CONTEC CMS600B-3 och Philips Lumify för att få resultat som inte beror på endast en maskin. Axiella upplösningen på CONTEC CMS600B-3 uppmättes med hjälp av ett gem till 0,61 mm och den laterala upplösningen till 1,27 mm med hjälp av ett snitt i cement. Maskinens måttmätningar hade en relativ avvikelse beroende på mätning. Resultat för reflektionskoefficienten visade att ultraljudsmaskinen har en funktion som kompenserar för attenuering och förstärker signaler med låga amplituder. Temperaturmätningarna undersöktes genom att skapa fantomer som efterliknar mänskliga vävnader med olika volymer och ytareor. En undersökning med ultraljudsmaskinerna visade att mer temperaturökning sker då ytarean ökas när volymen hålls konstant. Med avseende på säkerhet i temperaturökning, axiell upplösning och area/omkrets mått uppfyller CONTEC CMS600B-3 inte standarden och kan därmed inte användas inom sjukvården.
Diagnostics with ultrasound are based on propagation of mechanical waves and is used for imaging cross-section of the body in real-time. Performance, regarding contrast, resolution, and size measure, of CONTEC CMS600B-3, a relatively cheap machine is of interest. How volume of a phantom, its surface area, and frequency of the waves affects the heating of the tissues is also of interest. It was measured using ultrasound machines CONTEC CMS600B-3 and Philips Lumify to obtain results independent of the machine used. The axial resolution of CONTEC CMS600B-3 was established with a paperclip to be 0.61 mm and the lateral resolution was measured to be 1.27 mm using concrete with a triangular slit. Measurements of the machine had a relative deviation was depending on the measure. Results of the reflection coefficient indicated that CONTEC CMS600B-3 has a built-in function that compensates for loss of intensity due to attenuation and amplifies signals with lower amplitude to produce a B-mode image that the user can understand. Temperature measurements were done on phantoms that mimic the human body with different volumes and surface areas. An investigation with ultrasound machines showed an increase in temperature with increased surface area as the volume is held constant. When looking at safety with temperature rise, axial resolution and area/circumference measurements, CONTEC CMS600B-3 does not meet the standard and therefore cannot be used in healthcare.

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Zhu, Mengchen. "Real-time B-mode ultrasound image simulation and artifacts modelling of needles and brachytherapy seeds." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/12611.

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The training of ultrasound guided interventional procedures could benefit from ultrasound simulators that synthesize realistic-looking B-mode images of tissue and interventional tools, such as the needle. For a prostate brachytherapy simulator in particular, both the needle and seed images need to be synthesized. In this thesis, we propose an interpolation-based method for simulating needle and seed B-mode images in real time. We parametrize a needle or a seed B-mode image as a function of its position and orientation. We collect needle and seed images under various spatial configurations in a water-tank using a needle guidance robot. Then we use multi-dimensional tensor-product interpolation to simulate images of needles and seeds with arbitrary poses and positions using collected images. After further processing, the interpolated needle and seed images are superimposed on top of phantom or tissue image backgrounds. The similarity between the simulated and the real images is measured using a correlation metric. The results are also compared to in vivo images. Images in both the transverse and the sagittal planes are simulated. Artifacts associated with the needle and seed are studied in detail by experiments and by physical models. It is demonstrated that the bright band pattern associated with the sagittal needle images could be interpreted using a plate reflection model; the bright tails associated with the transverse needle images could be analyzed by simulating the back-scattered stress field from a sphere.

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Bennett, Michael J. "Signal processing techniques for ultrasonic tissue Doppler and real-time B-mode imaging in cardiology." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/10779.

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Coronary heart disease is the most common cause of death in the UK affecting more than one in five men and one in six women. The cause is generally a constriction of the coronary arteries which supply the heart muscle, or myocardium with blood. In around 95% of cases, the constriction is caused by the process of arteriosclerosis which results in the development of a plaque on the vessel wall. Even though these plaques tend to develop quite slowly, they are sometimes liable to sudden rupture, which causes clotting of the blood in the vessel and hence a sudden reduction in the supply of blood to the myocardium. This thesis is concerned with the signal processing techniques which are used in the form of Doppler Tissue Imaging (DTI) and real-time B-Mode imaging to study the motion of cardiac structures. Although these techniques are well suited to this task, improvements in B-mode contrast resolution and DTI velocity resolution are required if image quality and quantitative measurements are to reach a more acceptable level. Results are presented which demonstrate that the accuracy of the velocity estimations made using DTI can be improved with the use of model based signal processing techniques. The use of the fractional Fourier transform is explored in the context of coded excitation, which is a technique to allow improvements in imaging depth and axial resolution and results are shown which show that this technique is able to offer improvements similar to matched filtering. The combined techniques of empirical mode decomposition and the Hilbert spectrum are used to demonstrate a new interpretation of the physical process underlying non-linear acoustic wave propagation and the existing technique of tissue harmonic imaging.

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Lee, John Haeseon. "Measuring the absolute concentration of particles in suspension using high frequency B-mode ultrasound imaging." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105948.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis. Page 119 blank.
Includes bibliographical references (pages 115-118).
Concentration measurement of particles in suspension is an important procedure performed in biological and clinical laboratories. Existing methods based on instruments such as hemocytometers, coulter counters, and flow cytometers are often laborious, destructive, and incapable of in vivo measurements. An ultrasound-based method has several unique advantages. It can be nondestructive and noninvasive, which allows a much larger portion of the sample to be analyzed, improving the accuracy and decreasing required sample volume. Also, ultrasound methods have the potential for in vivo measurement in the clinical setting, where cell concentration in liquids such as cerebrospinal fluid can be measured noninvasively without requiring a lumbar puncture. In this work, a new method is presented that estimates absolute particle concentration from high frequency B-mode ultrasound images. The method is based on the detection and characterization of the echoes from individual particles to estimate the effective slice thickness of the image. Prior characterization of the sample is not required because the estimation relies only on parameters that are measured directly from the image. The particle type differential is also performed by using the backscatter coefficient. The method is demonstrated by measuring microsphere suspensions as well as human T cell suspensions using a mechanically scanned single element transducer imaging system and a VisualSonics Vevo 2100. The proposed method has a wide range of potential clinical applications including noninvasive measurement of cell concentration in biological fluids.
by John Haeseon Lee.
Ph. D.

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Wong, Chin Lin. "Beam Characterization and Systematics of the Bicep2 and Keck Array Cosmic Microwave Background Polarization Experiments." Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:13065012.

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Inflation, which posits an exponential expansion in the early universe, is well motivated since it resolves questions that are left unexplained by standard LCDM cosmology, such as the flatness and homogeneity of the universe. The exponential expansion of universe during inflation explains the structure in the universe by freezing out the quantum fluctuations of space. These quantum fluctuations are also expected to generate a background of gravitational waves which would then imprint a B-mode polarization signal on the Cosmic Microwave Background. The Bicep2 and Keck Array experiments search for B-mode polarization from inflationary gravitational waves in the Cosmic Microwave Background. Bicep2 and the Keck Array use small aperture, cold, on-axis refracting optics optimized to target the degree angular scales at which the inflationary B-mode polarization is expected to peak. In this thesis we describe the optical design of Bicep2 and the Keck Array. The small aperture design allows us to fully characterize the far-field performance of the instrument on site at the South Pole using thermal and amplified sources on the ground. We describe the efforts taken to characterize the main beam shapes of each polarization sensitive bolometer, as well as the differential beam paramters of each co-located orthogonally polarized detector pair. We study the residual temperature to polarization leakage induced by the beam mismatches after the principle modes have been mitigated in the analysis.
Physics

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Rossi, Benjamin. "Le récepteur pré-B au cours de la différenciation précoce des lymphocytes B chez l'homme : étude de sa structure et de son mode d'activation." Aix-Marseille 2, 2005. http://www.theses.fr/2005AIX22001.

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Mbongo, Nicolas. "Activite, mode d'action de complexes organometalliques et mecanismes de resistance a l'amphotericine b chez les leishmanies." Paris 11, 1997. http://www.theses.fr/1997PA114816.

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Wallis, Christopher. "Data analysis techniques useful for the detection of B-mode polarisation of the Cosmic Microwave Background." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/data-analysis-techniques-useful-for-the-detection-of-bmode-polarisation-of-the-cosmic-microwave-background(e97ec170-bc09-49cd-aaa3-99d2fb85c002).html.

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Asymmetric beams can create significant bias in estimates of the power spectra from cosmic microwave background (CMB) experiments. With the temperature power spectrum many orders of magnitude stronger than the B-mode power spectrum any systematic error that couples the two must be carefully controlled and/or removed. In this thesis, I derive unbiased estimators for the CMB temperature and polarisation power spectra taking into account general beams and scan strategies. I test my correction algorithm on simulations of two temperature-only experiments and demonstrate that it is unbiased. I also develop a map-making algorithm that removes beam asymmetry bias at the map level. I demonstrate its implementation using simulations. I present two new map-making algorithms that create polarisation maps clean of temperature-to-polarisation leakage systematics due to differential gain and pointing between a detector pair. Where a half wave plate is used, I show that the spin-2 systematic due to differential ellipticity can also be removed using my algorithms. The first algorithm is designed to work with scan strategies that have a good range of crossing angles for each map pixel and the second for scan strategies that have a limited range of crossing angles. I demonstrate both algorithms by using simulations of time ordered data with realistic scan strategies and instrumental noise. I investigate the role that a scan strategy can have in mitigating certain common systematics by averaging systematic errors down with many crossing angles. I present approximate analytic forms for the error on the recovered B-mode power spectrum that would result from these systematic errors. I use these analytic predictions to search the parameter space of common satellite scan strategies to identify the features of a scan strategy that have most impact in mitigating systematic effects.

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D'agostino, Maria Antonietta. "Evaluation de l'apport de l'échographie des enthèses (mode B et doppler puissant) au diagnostic de spondylarthrite." Paris 11, 2008. http://www.theses.fr/2008PA11T046.

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GENOT, ELIZABETH. "Proprietes et mode d'action d'un facteur de croissance des cellules b humaines : le bcgf-1 (lmwbcgf)." Paris 6, 1988. http://www.theses.fr/1988PA066249.

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Antonsson, Daniel. "A server application for Traffic Information Service : Broadcast." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1606.

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The need for increased safety and efficiency in civil aviation is pushing the introduction of Automatic Dependent Surveillance - Broadcast (ADS-B). The basic principle of ADS-B is that each aircraft is able to communicate its position and status over a radio data link to surrounding aircraft. In this way each aircraft obtains a detailed picture of the surrounding traffic. During a period of transition from today's radar surveillance to ADS-B many aircraft will not be equipped with the new data link technology and will therefore be invisible to the ADS-B equipped aircraft. The Traffic Information Service - Broadcast (TIS-B) has been conceived to be the solution to this problem. TIS-B is defined as a broadcast surveillance service in which data from the ordinary ground radar system is transmitted from a ground station to airborne systems, providing an air situation picture of the non-ADS-B stations.

The topics of this thesis are the definition and implementation of a TIS-B server. The presented solution is an evaluation TIS-B server that will receive data from a data-fusing tracker and provide one or several TIS-B ground stations with data filtered according to the settings of the server.

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Grauel, Lydia Sophia [Verfasser], Johannes [Akademischer Betreuer] Norgauer, Udo [Akademischer Betreuer] Markert, and Maja [Akademischer Betreuer] Mockenhaupt. "B-Mode Muster bei Patienten mit Psoriasis / Lydia Sophia Grauel. Gutachter: Johannes Norgauer ; Udo Markert ; Maja Mockenhaupt." Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2015. http://d-nb.info/1074139224/34.

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Law, Yuen Verfasser], Torsten [Akademischer Betreuer] [Kuhlen, and Stéphane [Akademischer Betreuer] Cotin. "Real-time simulation of B-mode ultrasound images for medical training / Yuen Law ; Torsten Kuhlen, Stéphane Cotin." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130792757/34.

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Genot, Elisabeth. "Propriétés et mode d'action d'un facteur de croissance des cellules B humaines le BCGF-1 (LMW-BCGF) /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37613794d.

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Kuchler, Kathrin. "Der Einfluss des Melkens auf Durchblutung und Morphologie der Rinderzitze untersucht mittels Color Angiographie und B-Mode Sonographie." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-128683.

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Granberg, Petter, and Roger Li. "Technical Verification and Validation of ADS-B/VDL Mode 4 for En-route Airspace and Major Terminal Areas." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-67423.

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This report is a technical verification and validation of Automatic Dependent Surveillance – Broadcast (ADS-B) over Very High Frequency Data Link Mode 4 (VDL Mode 4) for the use as surveillance in terminal areas and en-route airspace in non-radar areas. The main objective is to verify that ADS-B/VDL Mode 4 fulfils the technical requirements for an implementation at Kiruna airport, Sweden. Comparison has been made to the current requirements for Secondary Surveillance Radar (SSR). The work in this report has been conducted in three phases: preliminary study, tests and verification and validation. During the preliminary study documents primarily from EUROCONTROL and ICAO were used to find out which requirements that were applicable. The next part consisted of both practical tests and theoretical verification of the VDL Mode 4 performance. Finally the results from the tests were validated and put together in this report. Main conclusion from this report is that ADS-B/VDL Mode 4 fulfils the corresponding SSR requirements. Therefore ADS-B/VDL Mode 4 should be able to serve as primary mean for surveillance in non-radar areas. The results from this report will constitute a part of the technical subset of future safety case for ADS-B in non-radar areas. The complete safety case will be used to authorize ADS-B/VDL Mode 4 in non-radar airspace, both in Sweden and internationally.

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Thiel, Cetina. "Die sonographische Untersuchung (B-Mode, Farbdoppler und Power-Doppler) von Hauttumoren und deren Differentialdiagnosen bei Hund und Katze." Wettenberg : VVB Laufersweiler, 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969261543.

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Armentano, Margaret. "In vivo investigation of muscle behaviour during voluntary and electrically induced muscle contraction using B-Mode ultrasound imaging." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/7964/.

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Musculoskeletal Ultrasound Imaging (USI) is a growing field in literature. It has been proven to be a useful tool for investigating the properties of the muscle. There is growing interest in ultrasound imaging techniques for the description of skeletal muscle function, and different algorithms have been developed for this purpose. The majority of studies limit their focus on a particular area of the muscle, such as the aponeuroses, or on architectural parameters such as fiber length and pennation angle. The investigation of the entire muscle visualised on the ultrasound image may help elucidate the muscle function under normal conditions or when external factors compromise or alter the muscle function. Functional electrical stimulation (FES) is a technique based on the use of electrical current to activate skeletal muscles and facilitate their contraction. It is commonly used for strength training or in rehabilitation to accelerate or enhance the recovery of skeletal muscle's function. The ability of this technique to improve muscle performance in both healthy and diseased muscles has been demonstrated in research and in clinical practice. However the artificial nature of the muscle activation during FES leads to some important differences from the voluntary muscle contraction. Ultrasound Imaging (USI) is a potential tool that could provide objective measurements of the muscle's response during electrical stimulation, thus helping to describe and understand these differences. The aim of this study is to develop techniques based on USI that helps to elucidate the muscle function during electrical stimulation and allow comparison with voluntary contractions. Ultrasound videos were collected from healthy participants during experimental procedures involving voluntary and electrically induced muscle contractions. The videos were analysed using software algorithms for the tracking of features in US images. The resulting parameters were used as the basis for characterisation methods to describe the muscle contraction, both globally and locally. The effectiveness of the USI analysis techniques was tested and methods for extraction of physiological information from the video analysis were implemented. The regional distribution of muscle displacement during the tasks was analysed. Larger displacements were observed at deeper portions of the muscle in both the voluntary and the electrically induced contractions. Differential displacements across muscle depths were observed to differ during voluntary and FES contractions. The electric currents applied induce a uniform muscle contraction across different depths, most likely influenced by the way the electric field recruits muscle fibers. Muscle displacement was correlated to the force exerted by the muscle. Areas close to the deep aponeurosis have higher correlation with torque exerted and a second order polynomial can be used to define the relationship between displacement and torque. The relationship between the whole muscle displacement at different depths and the torque exerted was described using a polynomial surface fitting. Mechanical strain was used to map the muscle activation. Middle areas of the muscle undergo higher positive vertical strain (i.e. the muscle thickens) while deeper portions of the muscle are the most affected by shortening horizontal strain (i.e. the muscle shortens) in both voluntary and FES contractions. The muscle contractility was analysed through strain rate. A time-frequency analysis of the strain rate was performed. More frequency components and higher bandwidths were observed in FES induced contractions when compared to the voluntary. The frequency components might reflect the motor unit activation, suggesting that during FES all the motor units, firing at different rates, are recruited. In this project, USI was used as a tool to characterise the muscle behaviour locally. Regional muscle displacement and strain distribution have been used to elucidate the muscle function and quantify how different muscle areas are mechanically involved in the contraction. Strain rate was correlated with the muscle contractility and hypotheses regarding the correlation with motor units firing rate have been proposed. In conclusion a number of techniques were developed with the purpose to investigate the muscle function in normal conditions and when external factors, such as electrical stimulation, alter the natural muscle behaviour.

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Tisné, Carine. "Structures des sites b natif et mute du vih-1 : etude d'un nouveau mode de reconnaissance adn/proteine." Paris 7, 1998. http://www.theses.fr/1998PA077298.

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Les structures cristallographiques des differents complexes adn/nf-b ont fait apparaitre un nouveau mode de fixation a l'adn par l'intermediaire de dix longues boucles qui s'organisent autour de l'adn et realisent de nombreux contacts avec la chaine phosphodiester. Deux de ces boucles (les plus longues) realisent des liaisons hydrogene dans le grand sillon de l'adn. La reconnaissance par des boucles etant nouvelle, il etait interessant d'essayer de degager le role de l'adn dans l'interaction adn/nf-b. Ainsi, nous avons etudie, par rmn et modelisation moleculaire, la structure en solution de deux duplex de 16 paires de bases relatifs aux sites b du vih-1. Dans les deux cas, les donnees rmn ont mis en evidence un comportement dynamique des duplex que nous avons identifie comme un mouvement des brins phosphodiesters. Le duplex natif contenant les dix paires de bases du site b est en equilibre entre deux conformations extremes dont l'une presente des caracteristiques particulieres : toutes les paires de bases sont deplacees dans le grand sillon de l'adn et l'helice est courbee vers le grand sillon, comme observe dans certains complexes cristallographiques adn/nf-b. L'adn mute sur trois paires de bases est egalement en equilibre entre deux conformations, mais la mutation change la flexibilite de la chaine phosphodiester. L'ensemble des paires de bases ne peut plus etre translate vers le grand sillon qui, quelque soit la conformation, est plus profond et moins large que celui de la sequence native. Ces resultats structuraux associes a l'exploration approfondie des proprietes intrinseques de chaque duplex (calcul des potentiels electrostatiques et de l'accessibilite des atomes du grand sillon) nous permettent d'emettre des hypotheses quant a l'absence de fixation de nf-b sur le site mute, et de proposer un mode de reconnaissance specifique des sites b par nf-b. Les sites b attireraient la proteine en presentant, dans le grand sillon, les atomes qui forment des liaisons hydrogene avec nf-b, tres accessibles et avec la bonne polarite. Lorsque les phosphates sont neutralises, cette conformation utile a l'arrimage de nf-b deviendrait energetiquement moins favorable, et l'adn adopterait alors une conformation globale plus canonique, comme celle observee dans les complexes cristallographiques.

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Mallory, Ann Elizabeth. "Measurement of Meningeal Motion Using B-Mode Ultrasound as a Step Toward Understanding the Mechanism of Subdural Hematoma." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1387797814.

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Lee, Jen John. "Formação e processamento de imagens de ultrassom." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18152/tde-24062010-154946/.

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Imagens acústicas permitem a inspeção e análise de tecidos biológicos e outros materiais de forma não destrutiva, o que é desejado tanto para aprimorar e aumentar o conhecimento sobre o objeto analisado, quanto para diagnosticar ou assegurar a qualidade do mesmo. Este trabalho foi motivado pela falta de recursos quantitativos para análise e diagnósticos via imagens de ultrassom, normalmente baseados em métodos qualitativos, ou seja, experiência e bom senso dos inspetores, além da falta de sistemas de imageamento que permitam a aquisição do sinal puro de RF. Possuir métodos quantitativos de análise é essencial para o desenvolvimento de novos materiais piezelétricos, modelos biomédicos de tecidos e métodos de diagnóstico. Neste trabalho, foi desenvolvido um sistema eletro-mecânico de varredura sincronizado com o sistema de aquisição de sinais de ultrassom e formação de imagem por diferentes métodos de interpolação que permitiu o desenvolvimento de um algoritmo de segmentação de imagens baseado em watershed para separação e contagem de formas em modelos phantom de tecidos moles. Percebeu-se que o uso de um filtro estatístico de Wiener, mesmo sem grandes vantagens para análise qualitativa, possui resultado positivo como pré-processamento para segmentação automática.
Acoustic imaging allows the inspection and analysis of biological tissue and others materials in a non-destructive way, what is desired to improve the knowledge and to insure the quality about the analyzed object. This work was motivated by the lack of quantitative methods of analysis, usually based on qualitative diagnoses from experienced inspectors, what can vary, as well the lack of imaging systems where the pure RF signal of ultrasound could be acquired. Quantitative methods of analysis are highly desired when developing new piezoelectric materiais, biomedic phantom models and new diagnoses methods. It was developed in this work: an electrical-mechanic scanning system synchronized with the ultrasound acquisition device and image formation by different methods that allowed the development of an algorithm to prepare and to segment these images and different soft tissue phantom models. It was noticed that a statistic Wiener filter, even with no advantages for qualitative analysis of an image, improved the automatic segmentation of it.

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Florin, Charles Henri. "Automated Traffic Control for Smart Landing Facilities." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/36095.

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The Small Aircraft Transportation System (SATS) is a partnership between the FAA, the NASA, US aviation companies, universities and state and local aviation officials. The purpose of SATS is to develop a system to handle future increase in Air Traffic, reduce time-travel, develop automation in Air Traffic Control (ATC) and make better use of small aircraft and underused airports. The Smart Landing Facility (SLF) is an important part of the program. The SLF is a small airport upgraded with equipment to support SATS aircraft. Among the SLF equipment, SATS needs new detection equipment, and eventually automation. This thesis investigates different techniques to avoid data collision in aircraft radar responses, and to reduce delays between landings and take offs. First, the paper shows how and when the radar receiver can separate two overlapped radar responses. Second, to avoid transponders responses overlapping, requirements in terms of aircraft safety distance are computed, different conflicts in air traffic around the SLF are examined and a solution is proposed for each case. And finally, the thesis investigates how far SATS can go in developing an automatic ATC system and what the role of future human operator will be in ATC.
Master of Science

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Hensch, André [Verfasser]. "Stellenwert von B-Mode-, Power Doppler- und Kontrastverstärker-Sonographie bei RA-Patienten unter anti-TNF-α-Therapie / André Hensch." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2010. http://d-nb.info/102486510X/34.

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Lautwein, Alexander [Verfasser], Simon B. [Gutachter] Eickhoff, and Svenja [Gutachter] Caspers. "Volumetrische Veränderungen des erweiterten sozio-affektiven „Default Mode“ Netzwerks bei Schizophrenie / Alexander Lautwein ; Gutachter: Simon B. Eickhoff, Svenja Caspers." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2017. http://d-nb.info/1126096504/34.

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Weber, Annika [Verfasser]. "Vergleich von aktuellen diagnostischen Bildgebungsverfahren - B-Mode, CEUS und CT/MRT - zur Charakterisierung unklarer Raumforderungen der Niere / Annika Weber." Ulm : Universität Ulm, 2018. http://d-nb.info/1162953799/34.

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Smith, C. "The mode of action and selectivity of M&B 34790 and M&B 30755 in cotton and four weed species (Abutilon theophrasti, Echinochloa crusgalli, Polygonum lapathifolium, and Portulaca oleracea)." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381154.

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Øvland, Ragnhild. "Coherent Plane-Wave Compounding in Medical Ultrasound Imaging : Quality Investigation of 2D B-mode Images of Stationary and Moving Objects." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18834.

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Abstract:

Coherent plane-wave compounding is the coherent summation of several successive plane waves incident at different angles. This thesis presents results from simulations and in vitro and in vivo measurements of stationary and moving objects, with focus on loss of resolution and contrast due to object motion. Resolution and contrast results for several angle selections, angle sequences and object velocities with and without motion correction have been compared.It is shown that using a subset of plane-wave tilt angles by decimating the optimal selection introduces grating lobes which degrades the image contrast, while imaging with a lower maximum tilt angle degrades the lateral resolution. The contrast loss for decimation factor 2 was more significant for simulations than for in vitro measurements. While the contrast went from -40 to -30 dB for the simulations, a decimation factor of 4 was needed to degrade the contrast significantly for the measurements. Decimating the angle selection by a factor of 2 doubles the achievable frame rate. A reduction in maximum angle from 13.7 to 8.2 deg., which corresponds to an increase in transmit F-number from 2.1 to 3.5, gives less than 0.3 mm degradation of lateral resolution. The lateral resolution is of the order of 1 mm. This reduction in maximum angle increases the frame rate by a factor of 1.2.Axial point scatterer velocity leads to considerably worse image quality than for stationary scatterers, while the effect of lateral scatterer velocities is limited. The degree of contrast and resolution loss due to object motion is dependent on the selection of plane waves which constitute a frame, and the sequence in which the plane waves are transmitted. Using a subset of the optimal angle selection leads to improvement in image quality for an axial velocity of 10.0 cm/s for decimation factor 4, but not for decimation factor 2, even though the total scatterer movement per frame is reduced by the reduction of transmitted plane-waves. The loss of quality due to motion was less for fewer tilt angles, but the total image quality was still worse for many of these sets of angles due to grating lobes.The unwanted effects of motion for in vivo-measurements were not seen to the same extent as for simulated point scatterers, and working with the coherent plane-wave compound seems promising for moving objects.

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Dissertations / Theses on the topic 'B-mode'

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