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Dissertations / Theses on the topic 'Radar function'
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1
Butler, Joseph MacKay. "Tracking and control in multi-function radar." Thesis, University College London (University of London), 1998. http://discovery.ucl.ac.uk/1317909/.
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The phased array multi-function radar is an effective solution to the requirement for simultaneous surveillance and multiple target tracking. However, since it is performing the jobs usually undertaken by several dedicated radars its radar time and energy resources are limited. For this reason, and also due to the large cost of active phased array antennas, it is important for the strategies adopted in the control of the radar to be efficient. This thesis investigates and develops efficient strategies for multi-function radar control and tracking. Particularly the research has focused on the use of rotating array antennas and simultaneous multiple receive beam processing. The findings of the research challenge the traditional view that three or four fixed (static) array faces is the best antenna configuration for a multi-function radar system. By developing novel methods for the comparison of systems utilising different antenna configurations it is shown that a rotating array multi-function radar performs the surveillance function with a greater efficiency in its use of radar time than a static array system. Also, a rotating array system benefits from the ability to distribute the radar resources over the angular coverage in a way that is impossible with a static array system. A novel strategy is presented to achieve this, which allows the rotating array system to better support the realistic situation of a high concentration of radar tasks in a narrow angular sector. It is shown that the use of broadened transmit beams coupled with simultaneous multiple narrow receive beams can eliminate the compromise on radar beamwidth between the surveillance and tracking functions that is associated with multi-function radars. This technique would allow construction of multi-function radar systems with narrow beamwidths, giving improved tracking performance, without extending search frame times excessively. Efficient tracking strategies for both static array and rotating array multi-function radars are developed. They are applied through computer simulation to demonstrate tracking of highly manoeuvrable targets with a narrow beam multi-function radar. Track robustness is attained through the use of multiple beam track updating strategies at little cost in terms of radar time.
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Nazir, Mahvish. "Automotive radar target detection using ambiguity function." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6842/.
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The risk of collision increases, as the number of cars on the road increases. Automotive radar is an important way to improve road traffic safety and provide driver assistance. Adaptive cruise control, parking aid, pre-crash warning etc. are some of the applications of automotive radar which are already in use in many luxury cars today. In automotive radar a commonly used modulation waveform is the linear frequency modulated continuous waveform (FMCW); the return signal contains the range and velocity information about the target related through the beat frequency equation. Existing techniques retrieve target information by applying a threshold to the Fourier power spectrum of the returned signal, to eliminate weak responses. This method has a risk of missing a target in a multi-target situation if its response falls below the threshold. It is also common to use multiple wide angle radar sensors to cover a wider angle of observation. This results in detecting a large number of targets. The ranges and velocities of targets in automotive applications create ambiguity which is heightened by the large number of responses received from wide angle set of sensors. This thesis reports a novel strategy to resolve the range-velocity ambiguity in the interpretation of FMCW radar returns that is suitable for use in automotive radar. The radar ambiguity function is used in a novel way with the beat frequency equation relating range and velocity to interpret radar responses. This strategy avoids applying a threshold to the amplitude of the Fourier spectrum of the radar return. This novel radar interpretation strategy is assessed by a simulation which demonstrates that targets can be detected and their range and velocity estimated without ambiguity using the combined information from the radar returns and existing radar ambiguity function.
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Huang, Jen-Chih. "The ambiguity function of the stepped frequency radar." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA289533.
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Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering) Naval Postgraduate School, September 1994.Thesis advisor(s): G. S. Gill. "September 1994." Includes bibliographical references. Also available online.
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Charlish, A. B. "Autonomous agents for multi-function radar resource management." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1334115/.
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The multifunction radar, aided by advances in electronically steered phased array technology, is capable of supporting numerous, differing and potentially conflicting tasks. However, the full potential of the radar system is only realised through its ability to automatically manage and configure the finite resource it has available. This thesis details the novel application of agent systems to this multifunction radar resource management problem. Agent systems are computational societies where the synergy of local interactions between agents produces emergent, global desirable behaviour. In this thesis the measures and models which can be used to allocate radar resource is explored; this choice of objective function is crucial as it determines which attribute is allocated resource and consequently constitutes a description of the problem to be solved. A variety of task specific and information theoretic measures are derived and compared. It is shown that by utilising as wide a variety of measures and models as possible the radar’s multifunction capability is enhanced. An agent based radar resource manager is developed using the JADE Framework which is used to apply the sequential first price auction and continuous double auctions to the multifunction radar resource management problem. The application of the sequential first price auction leads to the development of the Sequential First Price Auction Resource Management algorithm from which numerous novel conclusions on radar resource management algorithm design are drawn. The application of the continuous double auction leads to the development of the Continuous Double Auction Parameter Selection (CDAPS) algorithm. The CDAPS algorithm improves the current state of the art by producing an improved allocation with low computational burden. The algorithm is shown to give worthwhile improvements in task performance over a conventional rule based approach for the tracking and surveillance functions as well as exhibiting graceful degradation and adaptation to a dynamic environment.
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Leon, Efrain. "Generation of the ambiguity function for ultra wideband radar waveforms." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA277913.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, December 1993.Thesis advisor(s): Gurnam S. Gill ; Adbel Aziz Mohamed Darwish. "December 1993." Includes bibliographical references.
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Kattekola, Sravanthi. "Weather Radar image Based Forecasting using Joint Series Prediction." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1238.
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Accurate rainfall forecasting using weather radar imagery has always been a crucial and predominant task in the field of meteorology [1], [2], [3] and [4]. Competitive Radial Basis Function Neural Networks (CRBFNN) [5] is one of the methods used for weather radar image based forecasting. Recently, an alternative CRBFNN based approach [6] was introduced to model the precipitation events. The difference between the techniques presented in [5] and [6] is in the approach used to model the rainfall image. Overall, it was shown that the modified CRBFNN approach [6] is more computationally efficient compared to the CRBFNN approach [5]. However, both techniques [5] and [6] share the same prediction stage. In this thesis, a different GRBFNN approach is presented for forecasting Gaussian envelope parameters. The proposed method investigates the concept of parameter dependency among Gaussian envelopes. Experimental results are also presented to illustrate the advantage of parameters prediction over the independent series prediction.
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Vicente, Ricardo Miguel F. P. "Characterization of Synthetic Aperture Radar Image Features of the Ocean as a Function of Wind Speed and High Frequency Radar Products." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/7424.
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High-definition source images for those used in this document are available here: http://hdl.handle.net/10945/13822Approved for public release, distribution unlimited
Assessment of coastal ocean conditions is valuable for both military and civilian operations. Remote sensing of those conditions can be even more valuable, particularly in the case of all-weather sensor types. The potential for better understanding of ocean conditions through the combination of remote sensing results was recognized here with the focus on SAR imagery and High Frequency (HF) radar-derived surface currents. The hypothesis that combining remote sensing products may improve results was tested using SAR imagery and available HF radar surface current maps along central California. Data were obtained from 2007-2010 when the network of HF radar stations was operating relatively continuously. Over the same time period, 780 archived SAR images were identified and, of those, 31 images were chosen for detailed assessment by identifying representative images under weak, moderate, and strong wind conditions. As expected, wind strength played a dominant role in determining the physical processes visible in the SAR imagery. Moderate wind speed of 24 m/s exhibited the most obvious ocean-related processes and the best correlation with features in the HF radar surface current maps. Surprising is the discovery that oceanographic features in the SAR imagery represent recent history of tracer advection over hours to days. As such, individual hourly, surface-current snapshots are not, perhaps, the best product for comparing with those features. Features in the daily-average currents, for example, appear more highly correlated with features in SAR imagery under moderate wind conditions.
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Cankaya, Erkan. "Use Of The Ambiguity Function Technique For Target Detection In Phase Coded Continuous Wave Radars." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606767/index.pdf.
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The goal of this thesis study is to investigate the Ambiguity Function Technique for
target detection in phase-coded continuous wave radar. Also, phase shift keying
techniques are examined in detail.
Continuous Wave (CW) Radars, which are also known as Low Probability of
Intercept (LPI) radars, emit continuous signals in time which are modulated by
either frequency modulation or phase modulation techniques. Modulation of the
transmitted radar signal is needed to estimate both the range and the radial velocity
of the detected targets. In this thesis, Phase Shift Keying (PSK) techniques such as
the Barker codes, Frank codes, P1, P2, P3, P4 codes will be employed for radar
signal modulation. The use of Ambiguity Function, which is a non-linear Time-
Frequency Representation (TFR), for target detection will be investigated in phasecoded
CW radars for different target scenarios.
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Zhang, Guifu. "Detection and imaging of targets in the presence of clutter based on angular correlation function /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6085.
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Akangol, Mehmet. "Target Detection By The Ambiguity Function Technique And The Conventional Fourier Transform Technique In Frequency Coded Continuous Wave Radars." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606766/index.pdf.
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Continuous Wave (CW) radars are preferred for their low probability of intercept by the other receivers. Frequency modulation techniques, the linear frequency modulation (LFM) technique in particular, are commonly used in CW radars to resolve the range and the radial velocity of the detected targets. The conventional method for target detection in a linear FMCW radar makes use of a mixer followed by a low-pass filter whose output is Fourier transformed to get the range and velocity information. In this thesis, an alternative target detection technique based on the use of the Ambiguity Function (AF) will be investigated in frequency modulated CW radars. Results of the AF-based technique and the conventional Fourier-based technique will be compared for different target detection scenarios.
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Paduru, Anirudh. "Fast Algorithm for Modeling of Rain Events in Weather Radar Imagery." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/1097.
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Weather radar imagery is important for several remote sensing applications including tracking of storm fronts and radar echo classification. In particular, tracking of precipitation events is useful for both forecasting and classification of rain/non-rain events since non-rain events usually appear to be static compared to rain events. Recent weather radar imaging-based forecasting approaches [3] consider that precipitation events can be modeled as a combination of localized functions using Radial Basis Function Neural Networks (RBFNNs). Tracking of rain events can be performed by tracking the parameters of these localized functions. The RBFNN-based techniques used in forecasting are not only computationally expensive, but also moderately effective in modeling small size precipitation events. In this thesis, an existing RBFNN technique [3] was implemented to verify its computational efficiency and forecasting effectiveness. The feasibility of modeling precipitation events using RBFNN effectively was evaluated, and several modifications to the existing technique have been proposed.
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Pillai, Samyuktha Muralidharan. "Structure-function studies of human SLC36 amino acid transporters." Thesis, Oxford Brookes University, 2011. http://radar.brookes.ac.uk/radar/items/6fc63f43-36b7-14bf-5f89-5ffb4626a869/1.
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The Solute Linked Carrier family 36 (SLC36) of integral membrane transport proteins has four members which are also known as the human Proton coupled Amino acid Transporters (hPATs).This is due to hPATs 1 and 2 having been functionally characterized as proton coupled transporters that bring about a 1:1 symport of H+ and an amino acid across the membrane (with optimum uptake at an extracellular pH of 5.5). Their main substrates were found to be the small neutral amino acids glycine, alanine and proline; however, in addition to these, PATs 1 and 2 were also observed to transport a range of other substrates including some pharmacologically active compounds. hPATs 3 and 4 were considered orphan transporters, with no information available except their mRNA localization in various tissues. Additionally there is no structural information available about the PAT family of transport proteins. The thesis has two broad aims. The first aim was to study the orphan PAT transporters and to investigate whether these proteins are also amino acids transporters and, if so, what their substrates are. The second aim was to use transmembrane domain software to predict the secondary structure of the PAT transporters using hPAT1 as the model protein. Epitope tags, luminometry and functional assays were used to test these predictions, and homology modelling then employed to gain a better understanding of the structure-function relationship of this transporter family. The results of both these areas of investigation are reported in this thesis. The orphan transporter hPAT4 was found to be a very high affinity electroneutral proline and tryptophan transporter when expressed in the Xenopus laevis oocyte system. Preliminary data for hPAT3 suggested uptake of proline at extracellular pH 7.4 in Xenopus laevis oocytes and in the mouse Sertoli cell line TM4. Membrane topology studies on hPAT1 provided experimental support for the prediction of 11 transmembrane domains for this transporter protein. Homology modelling indicates a region which might play a role in the substrate specificity of PAT proteins.
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Patton, Lee Kenneth. "On the Satisfaction of Modulus and Ambiguity Function Constraints in Radar Waveform Optimization for Detection." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1247595193.
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Jameson, Brian Douglas. "A NOVEL MULTI-FUNCTIONAL SOFTWARE-DEFINED RADAR: THEORY & EXPERIMENTS." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1375821039.
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Driessen, Anique Johanna Eduarda. "Exploring the combined use of electrical and hemodynamic brain activity to investigate brain function." Thesis, Oxford Brookes University, 2014. https://radar.brookes.ac.uk/radar/items/d5e7c357-e312-4fba-8cc5-774eff36180e/1/.
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This thesis explored the relationship between electrical and metabolic aspects of brain functioning in health and disease, measured with QEEG and NIRS, in order to evaluate its clinical potential. First the limitations of NIRS were investigated, depicting its susceptibility to different types of motion artefacts and the inability of the CBSI-method to remove them from resting state data. Furthermore, the quality of the NIRS signals was poor in a significant portion of the investigated sample, reducing clinical potential. Different analysis methods were used to explore both EEG and NIRS, and their coupling in an eyes open eyes closed paradigm in healthy participants. It could be reproduced that during eyes closed blocks less HbO2 (p = 0.000), more Hbb (p = 0.008), and more alpha activity (p = 0.000) was present compared to eyes open blocks. Furthermore, dynamic cross correlation analysis reproduced a positive correlation between alpha and Hbb (r: 0.457 and 0.337) and a negative correlation between alpha and HbO2 (r: -0.380 and -0.366) with a delayed hemodynamic response (7 to 8s). This was only possible when removing all questionable and physiological illogical data, suggesting that an 8s hemodynamic delay might not be the golden standard. Also the inability of the cross correlation to take non-linear relationships into account may distort outcomes. Therefore, In chapter 5 non-linear aspects of the relationship were evaluated by introducing the measure of relative cross mutual information. A newly suggested approach and the most valuable contribution of the thesis since it broadens knowledge in the fields of EEG, NIRS and general time series analysis. Data of two stroke patients then showed differences from the healthy group between the coupling of EEG and NIRS. The differences in long range temporal correlations (p= 0.000 for both cases), entropy (p< 0.040 and p =0.000), and relative cross mutual information (p < 0.003 and p < 0.013) provide the proof of principle that these measures may have clinical utility. Even though more research is necessary before widespread clinical use becomes possible.
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Winkler, Joseph W. "An Investigation into Ground Moving Target Indication (GMTI) Using a Single-Channel Synthetic Aperture Radar (SAR)." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3555.
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Synthetic aperture radar (SAR) was originally designed as an airborne ground-imaging radar technology. But it has long been desired to also be able to use SAR imaging systems to detect, locate, and track moving ground targets, a process called Ground Moving Target Indication (GMTI). Unfortunately, due to the nature of how SAR works, it is inherently poorly suited to the task of GMTI. SAR only focuses targets and image features that remain stationary during the data collection. A moving ground target therefore does not focus in a conventional SAR image, which complicates the process of performing GMTI with SAR systems. This thesis investigates the feasibility of performing GMTI with single-channel, unsquinted, broadside stripmap SAR despite this inherent limitation. This study focuses solely on the idealized case of direct energy returns from point targets on flat ground, where they and the airborne radar platform all move rectilinearly with constant speed. First, the various aspects of how SAR works, the signal processing used to collect the SAR data, and the backprojection image formation algorithm are explained. The effects of target motion are described and illustrated in actual and simulated SAR images. It is shown how the backprojection (BPJ) algorithm, typically used to image a stationary landscape scene, can also focus on moving targets when the target motion is known a priori. A SAR BPJ ambiguity function is also derived and presented. Next, the time-changing geometry between the airborne radar and a ground target is mathematically analyzed, and it is shown that the slant range between the radar and any ground target, moving or stationary, is a hyperbolic function of time. It is then shown that this hyperbolic range history causes the single-channel SAR GMTI problem to be underdetermined. Finally, a method is then presented for resolving the underdetermined nature of the problem. This is done by constraining a target's GMTI solution using contextual information in the SAR image. Using constraining information, a theoretical way is presented to perform limited GMTI with a single-channel SAR system by using a modified form of the BPJ imaging algorithm, and practical considerations are addressed that complicate the process. Instead of focusing on stationary pixels, this GMTI method uses the BPJ ambiguity function to search for moving targets on a straight path, such as a road, by performing matched filtering on a collection of moving pixels in a position-velocity image space. Nevertheless, it is concluded that for moving point targets, general GMTI with no path constraints is infeasible in practice with a single-channel SAR.
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Geldenhuis, Andre. "The Atmospheric Gravity Wave Transfer Function above Scott Base." Thesis, University of Canterbury. Physics and Astronomy, 2008. http://hdl.handle.net/10092/3698.
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Gravity waves have a significant dynamic effect in the mesosphere. In particular, they drive the mesospheric circulation and are the reason that the summer polar mesosphere is cooler than the winter polar mesosphere. This thesis examines whether the effects of gravity waves are largely determined by filtering effects which allow only gravity waves with certain properties to propagate into the atmosphere. The filtering of gravity waves above Scott Base, Antarctica is examined using a radiosonde derived gravity wave source function, an MF-radar derived mesospheric gravity wave climatology, and a model derived filtering function. Least squares fitting of the source function and filtering function to the observed mesospheric gravity wave climatology allows us to determine which gravity wave phase velocities and propagation direction are likely to be present in the mesosphere and the relative importance of filtering and sources in this region. It is concluded the blocking of eastward gravity waves is important in winter and westward waves in summer.
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Gillion, Erwan. "Contribution à l'estimation de la SER d'une cible navale en environnement réel : modélisation et mesures." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S120/document.
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Dans le cadre de la guerre électronique en environnement marin, on cherche généralement à améliorer la furtivité d'un navire militaire afin de le rendre plus difficile à détecter et à localiser. Pour cela, il faut réduire la valeur de sa Surface Équivalente Radar (SER) afin de la rendre négligeable face aux perturbations apportées par l'environnement. La pratique a montré que la valeur de la SER mesurée est fortement influencée par l'environnement. Les estimateurs développés à ce jour offrent de bonnes performances pour déterminer la SER d'une cible navale de petite dimension mais deviennent imprécis pour un objet de grande taille placé dans un milieu inhomogène tel que l'environnement marin. Notre objectif est de proposer une nouvelle méthode de calcul de la SER qui prend en considération la nature volumique de la cible ainsi que les phénomènes de propagation intrinsèques à l'environnement marin. Une dyade de Green associée à la propagation d'une onde radioélectrique dans un conduit d'évaporation en présence d'une mer lisse et parfaitement conductrice, est alors développée et proposée pour calculer la SER de cibles navales de grandes dimensionsIn the naval electronic warfare, it is necessary to improve the stealth of military vessels in order to make them more difficult to be detected and be located. For that, the Radar Cross Section (RCS) value must be reduced to be negligible compared to the environment’s clutter. Experience has shown that the value of the measured RCS is strongly influenced by the environment. Nowadays, estimators developed offer good performance to determine the RCS of small naval targets but become inaccurate for large objects placed in inhomogeneous medium such as the marine environment. Our goal is to propose a new RCS estimation method which takes into account large targets and propagation phenomena in martime environment. A dyadic Green function, related to the radio wave propagation in an evaporation duct over smooth and perfectly conducting sea, is then developed and proposed to calculate the RCS of large naval targets
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Tolman, Matthew A. "A Detailed Look at the Omega-k Algorithm for Processing Synthetic Aperture Radar Data." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2634.pdf.
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Touati, Nadjah. "Optimisation des formes d'ondes d'un radar d'aide à la conduite automobile, robustes vis-à-vis d'environnements électromagnétiques dégradés." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0031/document.
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Divers radars sont développés pour des besoins d’aide à la conduite automobile de sécurité mais aussi de confort. Ils ont pour but de détecter la présence d’obstacles routiers afin d’éviter d’éventuelles collisions. La demande actuelle en termes de capteurs radars pour l’automobile connaît une croissance importante et les technologies employées doivent garantir de bonnes performances dans un environnement dégradé par les signaux interférents des autres utilisateurs. Dans cette thèse, nous nous intéressons au développement d’un système radar performant en tout lieu et en particulier dans un contexte multi-utilisateurs. A ce propos, nous proposons de nouvelles formes d’ondes qui se basent sur la combinaison des codes fréquentiels de Costas et d’autres techniques de compression d’impulsion en exploitant les signaux de Costas modifiés. La conception adoptée permet, grâce à la diversité introduite, de synthétiser un nombre important de formes d’ondes. Nous avons, ensuite, exploité deux approches d’estimation des paramètres des cibles. La première, plutôt classique, se base sur le traitement Doppler dans un train d’impulsions cohérent. La deuxième, récente dans le domaine automobile, se base sur la technique dite de « Compressed Sensing ». Une adaptation de ces algorithmes pour les signaux proposés a été discutée dans des environnements bruités et multi-cibles. L’ensemble de ces travaux contribue à explorer de nouvelles formes d’ondes, autres que celles utilisées dans les radars actuels et à proposer un traitement innovant en réception, adapté aux radars en général et à l’automobile en particulierSeveral driver assistance radars are developed for security and comfort requirements. Their goal is among others to detect the presence of obstacles for collision avoidance. The current demand in terms of automotive radar sensors experience a significant growth and the technologies being employed must ensure good performances especially in an environment degraded by interfering signals of other users. In this thesis, we are interested in developing a radar system which is effective in all situations especially in a multi-user context. For this purpose, we propose novel radar waveforms based on the combination of frequency hopping Costas codes and other pulse compression techniques, using modified Costas signals. The design approach allows to synthesize a significant number of waveforms, thanks to the high diversity introduced. Afterwards, we have exploited two estimation of target parameters approaches. The first one, quite classic, is based on Doppler processing in a coherent pulse train. The second one, recent in the automotive field , is based on the Compressed sensing techniques. An adaptation of these algorithms to proposed signals is discussed in noisy and multi-target environments. All these works contribute in one hand to explore novel radar waveforms, complement to those currently used in automotive radars and in another hand to propose an innovative processing at the receiver level, suited to radar applications in general and automotive ones in particular
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Gassier, Ghislain. "Contributions au Radar Passif sur Signaux d'Opportunité de Type Télévision Numérique Terrestre." Thesis, Toulon, 2016. http://www.theses.fr/2016TOUL0007/document.
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L’étude traite de la détection de cibles mobiles dans un contexte de radar passif bistatique utilisant les émetteursde télévision numérique TNT (DVB-T) comme émetteurs d’opportunité. Outre leur présence généralisée sur leterritoire, l’intérêt de ces émissions réside dans leur relative largeur de bande permettant une bonne précisiond’estimation. Le principal inconvénient de ce type d’approche réside dans l’éblouissement par le signal en trajetdirect, des échos de très faible intensité des cibles d’intérêt. Après un rappel du principe du radar bistatique etde la norme OFDM utilisée par les signaux TNT, une première étude donne une construction originale du signalde référence dans le cas multi-capteurs : le signal de référence est construit par un traitement d’antenne de typeCAPON où le balayage des paramètres optimaux est remplacé par la connaissance de signaux pilotes inséré dansles symboles OFDM. Ensuite le rapport se focalise sur l’estimation d’un filtre de canal multitrajet à partir dela connaissance de la modulation OFDM utilisée. Ce filtre, d’abord étudié comme réjecteur de fouillis originalavant détection par la fonction d’ambiguïté, donne des résultats semblables aux méthodes classiques de réjectionde fouillis standard. Étendu à toutes les fréquences Doppler, son module au carré est utilisé comme un nouveaudétecteur présentant un très faible niveau de clutter, surpassant ainsi la fonction d’ambiguïté. Une interprétationen terme de traitement d’antennes du nouveau détecteur ouvre la voie à des variantes haute-résolution de celui-ci.La validité du nouveau détecteur est illustrée par des résultats sur données réellesThe study focuses on moving target detection from passive bistatic radar with DVB-T transmitters used asopportunity transmitters. In addition to their widespread geographical coverage, they allow a good estimationaccuracy due to their quite large bandpass. Nevertheless the continuous powerful direct path masks the verylow intensity echoes of targets of interest. The passive bistatic radar principle and the CP-OFDM standardused by DVB-T are briefly reminded, then, a new first study of reference signal retrieving in multiple sensorsconfiguration is given : the reference signal is built using a Capon receptor where the parameters scan is replacedby the knowledge of pilot signals inserted in the OFDM symbols. Next, the report addresses the multipath channelestimate by using the OFDM signal structure. This channel is firstly studied for clutter rejection before detectionfrom the cross ambiguity function (CAF). We obtain similar results than those of the classical rejection methods.This channel is extended to the whole Doppler shift, and its squared modulus acts as a new low clutter detectorthat outperforms classical CAF. A virtual beamforming interpretation of the channel estimation opens a new pathtowards high resolution array processing. Results given on real data illustrate the validity of this new channeldetector (CHAD)
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Bennett, Patricia Helen. "Relationality and health : developing a transversal neurotheological account of the pathways linking social connection, immune function, and health outcomes." Thesis, Oxford Brookes University, 2013. https://radar.brookes.ac.uk/radar/items/bc0bd545-799e-455f-b5bc-40d74dcd946a/1/.
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This thesis is a transdisciplinary investigation of the link between social connection and health outcomes. Its twofold aim is to explore the nature of this relationship and build a theoretical model for a possible causal chain between the two, and to develop and deploy a new model for engaging the very different discourses of theology and neuroscience. To this end it draws on both theological reflection and on experimental scientific data from cognitive neuroscience and psychoneuroimmunology. The opening half of the work establishes the wider epistemological and methodological frameworks within which the project is set, and also the specific framework for the particular area of study. The first of these involves a critical analysis of the tensions at the heart of the dialogue between science and religion, and of the specific difficulties faced by the emerging sub-discipline of neurotheology. It then dissects and further develops the interdisciplinary dialogical model devised by J Wentzel van Huyssteen, in order to enable it to generate and support additional transdisciplinary outputs. In the second of the two framework arenas, the concept of health itself is first explored, and then epidemiological, Biblical, and immunological accounts of the link between relational connection and health are examined in order to establish that sufficient common ground exists to warrant a neurotheological approach to investigating the question of how the two are connected. The second half of the thesis then uses the developed model as a basis for engaging theological and neuroscientific perspectives on human relationality. This takes the form of three transversal encounters, each centred around a specific aspect of this: relationality as basic, as emergent, and as realised. From the output of these three dialogical interactions, a neurotheologically framed argument is developed to support the contention that relationality is an emergent phenomenon of a complex system concerned with social monitoring and response, and thus the way in which it is realised can exert causal constraints on system components. Finally a theoretical model is derived from this argument for a pathway linking relational experience to health outcomes via alterations in allostatic maintenance mechanisms.
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Johnson, Paul E. "Uncertainties in Oceanic Microwave Remote Sensing: The Radar Footprint, the Wind-Backscatter Relationship, and the Measurement Probability Density Function." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/71.
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Oceanic microwave remote sensing provides the data necessary for the estimation of significant geophysical parameters such as the near-surface vector wind. To obtain accurate estimates, a precise understanding of the measurements is critical. This work clarifies and quantifies specific uncertainties in the scattered power measured by an active radar instrument.
While there are many sources of uncertainty in remote sensing measurements, this work concentrates on three significant, yet largely unstudied effects. With a theoretical derivation of the backscatter from an ocean-like surface, results from this dissertation demonstrate that the backscatter decays with surface roughness with two distinct modes of behavior, affected by the size of the footprint. A technique is developed and scatterometer data analyzed to quantify the variability of spaceborne backscatter measurements for given wind conditions; the impact on wind retrieval is described in terms of bias and the Cramer-Rao lower bound. The probability density function of modified periodogram averages (a spectral estimation technique) is derived in generality and for the specific case of power estimates made by the NASA scatterometer. The impact on wind retrieval is quantified.
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Kokandi, Samih A. "The effect of Vitamin D status on lung function and airway inflammation in adults in Saudi Arabia and the UK." Thesis, Oxford Brookes University, 2017. https://radar.brookes.ac.uk/radar/items/1e161870-0197-4182-b8a3-b7a530930af2/1/.
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Vitamin D deficiency is a worldwide health problem and more extensively present in the gulf countries such as Saudi Arabia and in high latitude countries such as the United Kingdom. Many previous cross-sectional studies have investigated the correlation between vitamin D status and lung function, but the effect of vitamin D status on lung function and airway inflammation is still debatable. This project aimed to investigate the effect of vitamin D intervention through pharmacological supplements or dietary intake, on lung function and airway inflammation, among asthmatic adults in Saudi Arabia and in healthy individuals in the United Kingdom. The main findings of the study were; vitamin D deficiency is highly prevalent in asthma participants in Saudi Arabia (86%) and in healthy individuals in the UK (81%). Asthma participants with higher serum vitamin D levels had trend of better lung function (FEV1, P 0.287; FVC, P 0.391), slightly lower fractional exhaled nitric oxide levels (P 0.719) and lower blood inflammatory biomarkers, however, did not reach significant levels. Healthy participants with higher vitamin D levels had also better lung function (FEV1, P 0.104, FVC, P 0.158) but no differences in airway inflammation. Vitamin D intervention through oral supplements or dietary intervention for three weeks, significantly increased serum vitamin D levels (Supplement, P < 0.001, dietary, P 0.002) and improved lung function, especially the forced vital capacity (P 0.031), but did not have effects on airway inflammation. Dietary vitamin D intake was lower than the recommendation in both groups. During the study sun-exposure was at the minimal level due to hot weather in Saudi and cold and cloudy weather in the UK. Vitamin D intervention did not affect weight or percentage of body fat. Both chemiluminescence immunoassay and liquid chromatography-tandem mass spectrometry method can be used in measuring serum vitamin D levels but they cannot be used interchangeably due to systematic differences. However, they showed an acceptable agreement levels. Overall, the study found that vitamin D supplement in high dose, low dose or dietary intervention were effective in raising serum vitamin D level and had a trend of positive effect on lung function but not airway inflammation.
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Pan, Guangdong. "Electromagnetic Backscattering Studies of Nonlinear Ocean Surfaces." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1204559229.
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Šulc, Martin. "Rozpoznávání pohybujícího se objektu pomocí MIMO radaru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220219.
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The aim of this thesis is to estimate parameters of the moving target using different radar configurations. First the Doppler effect and the time delay of the received signal is examined. The investigation of these phenomenons is made for radial and non-radial movement of simple monostatic radar configuration and after that for the bistatic and multistatic MIMO configuration. The ambiguity function is presented for all these configurations. The ambiguity function is then used to estimate target parameters from the received signal. The received signal model and ambiguity function for the monostatic radar configuration is developed using Matlab software. Finally the practical use of these implementations is presented and compared.
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Crockett, Mark T. "Target Motion Estimation Techniques for Single-Channel SAR." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4111.
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Synthetic aperture radar (SAR) systems are versatile, high-resolution radar imagers useful for providing detailed intelligence, surveillance, and reconnaissance, especially when atmospheric conditions are non-ideal for optical imagers. However, moving targets in SAR images are smeared. Along-track interferometry is a commonly-used method for extracting the motion parameters of moving targets but requires a dual-aperture SAR system, which may be power- size- or cost-prohibitive. This thesis presents a method of estimating target motion parameters in single-channel SAR data given geometric target motion constraints. I test this method on both simulated and actual SAR data. This estimation method includes an initial estimate, computation of the SAR ambiguity function, and application of the target motion constraints to form a focused image of the moving target. The constraints are imposed by assuming that target motion is restricted to a road. Finally, I measure its performance by investigating the error introduced in the motion estimates using both simulated and actual data.
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Štukovská, Petra. "Algoritmy detekce radarových cílů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-451229.
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This thesis focuses on detection algorithms of radar targets, namely on group of techniques for removing of disturbing reflections from static objects - clutter and for suppression of distortion products caused by the phase noise of the transmitter and receiver. Methods for distortion suppression in received signal are designed for implementation in the developed active multistatic radar, which operates in the code division multiplex of several transmitters on single frequency. The aim of the doctoral thesis is to design, implement in tool for technical computing MATLAB and analyze the effectiveness and computational complexity of these techniques on simulated and real data.
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Sahin, Mehmet Ozgur. "Constructions Of Resilient Boolean Functions With Maximum Nonlinearity." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606458/index.pdf.
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In this thesis, we work on the upper bound for nonlinearity of t-resilient Boolean functions given by Sarkar and Maitra, which is based on divisibility properties of spectral weights of resilient functions and study construction methods that achieve the upper bound.
One of the construction methods, introduced by Maity and Johansson, starts with a bent function and complements some values of its truth table corresponding to a previously chosen set of inputs, S, which satisfies three criteria. In this thesis, we show that a fourth criterion is needed for t-resiliency of the resulting function, and prove that three criteria of Maity and Johansson do not guarantee resiliency.
We also work on other constructions, one by Sarkar and Maitra, which uses a Maiorana-McFarland like technique to satisfy the upper bound and the other by Tarannikov, which satisfies the nonlinearity bound using a technique with low computational complexity. However, these methods have tendency to maximize the order of resiliency for a given number of variables, therefore one cannot construct functions for all possible resiliency values given the number of variables, using this method.
We further go into details and compute the auto-correlation functions of the constructed Boolean functions to find the absolute indicator and sum-of-squared-errors for each of them. We also provide a comparison of Boolean functions constructed by other techniques given in the literature, together with the ones studied in this thesis.
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Kavut, Selcuk. "Boolean Functions With Excellent Cryptographic Properties In Autocorrelation And Walsh Spectra." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609795/index.pdf.
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We introduce a steepest-descent-like search algorithm for the design of Boolean functions,
yielding multiple desirable cryptographic properties in their Walsh and autocorrelation spectra
together. The algorithm finds some Boolean functions on 9, 10, 11, 13 variables with very
good cryptographic properties unattained in the literature. More specifically, we have discovered
9-variable rotation symmetric Boolean functions (RSBFs) having nonlinearity of
241, which exceeds the bent concatenation bound and has remained as an open question in
the literature for almost three decades. We have then shown that there is no RSBF having
nonlinearity greater than 241, and that there are 8x189 many RSBFs having nonlinearity of
241, such that, among them there are only two that are different up to the affine equivalence.
We also propose a generalization to RSBFs and dihedral symmetric Boolean functions (DSBFs),
which improves the nonlinearity result of 9-variable Boolean functions to 242. Further,
we classify all possible permutations (362, 880) on the input variables of 9-variable
Boolean functions and find that there are only 30 classes, which are different with respect
to the linear equivalence of invariant Boolean functions under some permutations. Some of
these classes and their subsets yield new 9-variable Boolean functions having the nonlinearity
of 242 with different autocorrelation spectra from those of the Boolean functions found in generalized RSBF and DSBF classes. Moreover, we have attained 13-variable balanced
Boolean functions having nonlinearity of 4036 which is greater than the bent concatenation
bound of 4032, and improves the recent result of 4034.
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Nowak, Michael J. "Mixed Modulation for Remote Sensing with Embedded Navigation." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1462295752.
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Chen, Lin. "MEASUREMENTS OF AUTOCORRELATION FUNCTIONS USING A COMBINATION OF INTRA- AND INTER-PULSES." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1437748779.
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Iskander, D. R. "The Generalised Bessel function K distribution and its application to the detection of signals in the presence of non-Gaussian interference." Thesis, Queensland University of Technology, 1997.
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Ozel, Omur. "Optimal Resource Allocation Algorithms For Efficient Operation Of Wireless Networks." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610732/index.pdf.
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In this thesis, we analyze allocation of two separate resources in wireless networks: transmit power and buffer space. Controlled allocation of power can provide good performance for both users and the network. Although centralized mechanisms are possible, distributed power control algorithms are preferable for efficient operation of the network. Viewing distributed power allocation as the collection of rational decisions of each user, we make game theoretic problem formulations, devise distributed algorithms and analyze them. First, equilibrium analysis of a vector power control game based on network energy efficiency in a multiple access point wireless network is presented. Then, a distributed mechanism is proposed that can smooth admission control type power control so that every user can stay in the system. Introducing a new externality into utility function, a game theoretic formulation that results in desired distributed actions is made. Next, the proposed externality is investigated in a control theoretic framework. Convergence of gradient based iterative power updates are investigated and stability of corresponding continuous time dynamical system is established. In the final part of the thesis, allocation of buffer space is addressed in a wireless downlink using a queueing theoretic framework. An efficient algorithm that finds optimal buffer partitioning is proposed and applications of the algorithm for different scenarios are illustrated. Implications of the results about cross layer design and multiuser diversity are discussed.
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Akroush, Muftah Emhemed. "Optimal Linear Filtering For Weak Target Detection in Radio Frequency Tomography." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton158273299902246.
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Evers, Aaron S. "Evaluation and Application of LTE, DVB, and DAB Signals of Opportunity for Passive Bistatic SAR Imaging." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1398768956.
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Guio, Patrick. "Etude de paramètres ionosphériques à l'aide des raies de plasma électroniques observées à Eiscat." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10253.
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Ce travail présente une étude des raies de plasma observées à l'aide du radar à diffusion incohérente EISCAT. Le travail est centré sur deux points. Tout d'abord, la conception d'une expérience raies de plasma pour le radar EISCAT, avec une résolution spatiale améliorée. Puis, la comparaison de données raies de plasma acquises avec le radar EISCAT avec une théorie améliorée sur l'intensité et le décalage Doppler en fréquence des raies de plasma. Pour améliorer la résolution spatiale, nous avons conçu la première expérience raies de plasma mettant en oeuvre la technique du code alternatif. Cette expérience a été tournée avec succès avec une résolution spatiale de 3 km au lieu de 40-50 km obtenu avec les techniques conventionnelles. Parce qu'il est très difficile de construire un modèle cohérent de la fonction de distribution des vitesses des électrons satisfaisant tous les intervalles d'énergies pertinents, nous avons construit une représentation adéquate de la distribution des vitesses des électrons en séparant la distribution en deux populations : la thermique et la suprathermique. La population thermique est représentée par la fonction de Spitzer qui tient compte de l'effet d'un champ électrique et/ou d'un gradient de température. La population suprathermique est déduite du flux angulaire d'énergie calculé grâce à un modèle numérique du transport des électrons. Un code numérique a été développé pour calculer la fonction diélectrique et la fonction réduite de distribution des vitesses pour toutes distributions des vitesses à deux dimensions dont nous avons besoin pour modéliser l'intensité et le décalage Doppler en fréquence des raies de plasma. Nous avons pu reproduire les caractéristiques de l'intensité et du décalage Doppler en fréquence des raies de plasma avec des données mesurées avec le radar VHF EISCAT. En particulier, nous avons identifié deux pics étroits dans la distribution des vitesses des suprathermiques comme la signature de la photo-ionisation de N_2 et O. Ces pics ont été observés sur les données. L'effet d'un gradient de température - qui produit une correction importante au décalage Doppler des raies de plasma - a été pris en compte plus précisement que précédemment en calculant numériquement les intégrales singulières, au lieu d'utiliser les premiers termes d'une expansion en séries comme auparavant. C'est important car cela a permis pour la première fois à un modèle de reproduire précisément l'intensité et le décalage Doppler des raies de plasma mesurés par une expérience EISCAT.
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Nishimura, Koji. "Functional extension of atmospheric radar with digital receiver array." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/135947.
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Erguven, Sait. "Path Extraction Of Low Snr Dim Targets From Grayscale 2-d Image Sequences." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607723/index.pdf.
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In this thesis, an algorithm for visual detecting and tracking of very low SNR targets, i.e. dim targets, is developed. Image processing of single frame in time cannot be used for this aim due to the closeness of intensity spectrums of the background and target. Thereforechange detection of super pixels, a group of pixels that has sufficient statistics for likelihood ratio testing, is proposed. Super pixels that are determined as transition points are signed on a binary difference matrix and grouped by 4-Connected Labeling method. Each label is processed to find its vector movement in the next frame by Label Destruction and Centroids Mapping techniques. Candidate centroids are put into Distribution Density Function Maximization and Maximum Histogram Size Filtering methods to find the target related motion vectors. Noise related mappings are eliminated by Range and Maneuver Filtering. Geometrical centroids obtained on each frame are used as the observed target path which is put into Optimum Decoding Based Smoothing Algorithm to smooth and estimate the real target path. Optimum Decoding Based Smoothing Algorithm is based on quantization of possible states, i.e. observed target path centroids, and Viterbi Algorithm. According to the system and observation models, metric values of all possible target paths are computed using observation and transition probabilities. The path which results in maximum metric value at the last frame is decided as the estimated target path.
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Mustafa, Ahmad M. "Performance of resonant radar target identification algorithms using intra-class weighting functions /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260859493835.
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Hammami, Imen. "Fusion d'images de télédétection hétérogènes par méthodes crédibilistes." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0034/document.
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Avec l’avènement de nouvelles techniques d’acquisition d’image et l’émergence des systèmes satellitaires à haute résolution, les données de télédétection à exploiter sont devenues de plus en plus riches et variées. Leur combinaison est donc devenue essentielle pour améliorer le processus d’extraction des informations utiles liées à la nature physique des surfaces observées. Cependant, ces données sont généralement hétérogènes et imparfaites ce qui pose plusieurs problèmes au niveau de leur traitement conjoint et nécessite le développement de méthodes spécifiques. C’est dans ce contexte que s’inscrit cette thèse qui vise à élaborer une nouvelle méthode de fusion évidentielle dédiée au traitement des images de télédétection hétérogènes à haute résolution. Afin d’atteindre cet objectif, nous axons notre recherche, en premier lieu, sur le développement d’une nouvelle approche pour l’estimation des fonctions de croyance basée sur la carte de Kohonen pour simplifier l’opération d’affectation des masses des gros volumes de données occupées par ces images. La méthode proposée permet de modéliser non seulement l’ignorance et l’imprécision de nos sources d’information, mais aussi leur paradoxe. Ensuite, nous exploitons cette approche d’estimation pour proposer une technique de fusion originale qui permettra de remédier aux problèmes dus à la grande variété des connaissances apportées par ces capteurs hétérogènes. Finalement, nous étudions la manière dont la dépendance entre ces sources peut être considérée dans le processus de fusion moyennant la théorie des copules. Pour cette raison, une nouvelle technique pour choisir la copule la plus appropriée est introduite. La partie expérimentale de ce travail est dédiée à la cartographie de l’occupation des sols dans les zones agricoles en utilisant des images SPOT-5 et RADARSAT-2. L’étude expérimentale réalisée démontre la robustesse et l’efficacité des approches développées dans le cadre de cette thèseWith the advent of new image acquisition techniques and the emergence of high-resolution satellite systems, remote sensing data to be exploited have become increasingly rich and varied. Their combination has thus become essential to improve the process of extracting useful information related to the physical nature of the observed surfaces. However, these data are generally heterogeneous and imperfect, which poses several problems in their joint treatment and requires the development of specific methods. It is in this context that falls this thesis that aimed at developing a new evidential fusion method dedicated to heterogeneous remote sensing images processing at high resolution. In order to achieve this objective, we first focus our research, firstly, on the development of a new approach for the belief functions estimation based on Kohonen’s map in order to simplify the masses assignment operation of the large volumes of data occupied by these images. The proposed method allows to model not only the ignorance and the imprecision of our sources of information, but also their paradox. After that, we exploit this estimation approach to propose an original fusion technique that will solve problems due to the wide variety of knowledge provided by these heterogeneous sensors. Finally, we study the way in which the dependence between these sources can be considered in the fusion process using the copula theory. For this reason, a new technique for choosing the most appropriate copula is introduced. The experimental part of this work isdevoted to land use mapping in case of agricultural areas using SPOT-5 and RADARSAT-2 images. The experimental study carried out demonstrates the robustness and effectiveness of the approaches developed in the framework of this thesis
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De, Keyser Rien. "Spatial structuring in trait variation in Polyommatus icarus in a functional context." Thesis, Oxford Brookes University, 2012. https://radar.brookes.ac.uk/radar/items/ccd80171-b454-4ce0-a43a-b4fe5744037e/1/.
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The Common blue butterfly, Polyommatus icarus (Rott,) , is widespread throughout its Palaearctic distribution and persists in areas with differing climatic conditions. It is known to be a highly variable butterfly with marked within and between population variation in morphology, thermal biology, and voltinism. These traits together with allozymes and a neutral DNA marker (AFLP) variation are studied here to understand how geographic trait variation is related to environmental variation. The approach adopted here is to study this along a latitudinal cline of temperature and photoperiod, using four populations from south to north within mainland Britain. AFLP differences, but not allozyme variation, indicate genetic structuring, with an isolation by distance effect. Enzyme diversity of P. icarus butterflies in the British Isles is lower than on mainland Europe, indicative of a past bottleneck. This, combined with selection on, or drift in, the allozymes could cause for a lack of population structure in this marker. Despite high levels of gene flow between populations, local adaptation is possible, as differentiation in certain allozyme loci was found (PGM and PGI). Populations differed in their response to developmental cues. Northern populations have an obligate diapause strategy and southern populations' development times differ in response to temperature, indicating local variation in response to environmental conditions. Populations differed in wing morphology (size, shape and melanisation) but this was not related to latitude. Experimental determination of heating rates in different basking positions and thoracic temperature at take-off revealed no strong relationships of the morphological characteristics with heating or cooling rates and an indication of relationship with PGI alleles. It is suggested that m comparison to larger butterflies morphological variation IS unconstrained by thermal requirements. The persistence and widespread occurrence of this butterfly may be a consequence of the variability of traits within this butterfly.
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Taylor-Wells, Jennina Charlotte. "Structural and functional investigation of the organic anion transporting polypeptide 1B1 (OATP1B1)." Thesis, Oxford Brookes University, 2013. https://radar.brookes.ac.uk/radar/items/df4e36df-30b8-4e94-afac-c5785f308d47/1/.
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Membrane transport proteins are the gatekeepers of the cell membrane, transporting compounds in and out of the cell. The organic anion transporting polypeptides (OATPs) are a family of transport proteins expressed in a variety of tissues, including absorptive I excretory cells of the liver and kidney. OATPs transport an array of endogenous and xenobiotic compounds including bile salts, thyroid hormones, statins and anti-cancer drugs. Therefore this protein family play an important role in cell homeostasis and drug disposition, and are implicated in disease and drug-drug interactions. However there is little information available regarding the structural properties of OATPs, which would reveal how the proteins fold and bind to substrates. To help further this understanding, the topology and signature sequence of the hepatocyte specific isoform OATPI B 1 have been investigated using a HEK293T cell model. OATP I B 1 was expressed in HEK293T cells and transport assayed using the substrate estrone-3-sulfate. Topology prediction programs were employed to map the transmembrane domains (TMs), which predicted a consensus of 12TMs with internal amino (N) and carboxyl (C) termini. The topology was studied experimentally using a FLAG epitope system, whereby the FLAG epitope was inserted into the putative extracellular/intracellular and terminal regions of the protein. Detection of FLAG antibody bind ing was quantified by Juminometry and visualised qualitatively using confocal microscopy. Results revealed that the pred icted internal N and C termini of the protein were external, in contrast to the predictions and current literature. A novel model has been generated from this data, encompassing these results and the current literature. All OATPs contain a conserved 13 amino acid signature sequence (D-X-RW (1,V)-GAWW-X-G-(F,L)-L) which spans the putative extracellular loop 3 and TM6, the function of which is not known. Six conservative mutations were made using site-directed mutagenesis; D251E, R253K, W254F, W258/259F and N261A. Kinetic, Iuminometric and immunofluorescence analysis revealed that all mutations except N261A reduced transport and expression on the membrane. The reduction in expression combined with the presence of structurally important arginine and tryptophan residues at the extracellular/TM interface indicate that this sequence may be important for membrane anchoring and/or protein fold ing. This knowledge of OATP structure and function is imperative to the understand ing the role of these proteins in the bind ing of endogenous and xenobiotic compounds.
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Imbulgoda, Liyangahawatte Gihan Janith Mendis. "Hardware Implementation and Applications of Deep Belief Networks." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1476707730643462.
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Graves, Leo P. "Taking a closer look : exploring the functional roles of P10 in baculovirus-infected cells." Thesis, Oxford Brookes University, 2016. https://radar.brookes.ac.uk/radar/items/7f408c91-e7eb-4ae7-bb0a-3bc3d20e7e89/1/.
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P10 is a small, highly expressed baculovirus protein whose function continues to be a mystery. Believed to be non-essential during virus infection, P10 is associated with a number of intracellular structures with suggested roles in polyhedron formation, nuclear stability and lysis. The work presented here aimed to elucidate the functional role of this protein during virus infection of cell cultures. To investigate the role of P10 during infection, a variety of Autographa californica nucleopolyhedrovirus (AcMNPV) mutants were constructed by a process of co-transfection and plaque-purification. These recombinant viruses included; a p10 deletion and associated rescue virus that confirmed that P10 is essential for nuclear lysis and the formation of an intact polyhedral envelope. Additional virus recombinants to investigate the host-cell specificity of P10 were explored with the replacement of the AcMNPV P10 coding region with that from Spodoptera frugiperda (Sf) NPV (Ac_sfp10). The resulting low expression of SfMNPV P10 resulted in the absence of a P10 perinuclear cage, nuclear lysis and induced cytoxic effects. To determine whether reduced P10 synthesis was a factor in P10 function, a set of nine AcMNPV promoter deletions, made upstream from the ATG translation site of the p10 coding region, were constructed. Analysis of these viruses showed that a decrease in P10 expression correlated with a reduction in promoter length and a concomitant decrease of nuclear lysis with reduced P10 expression. This thesis describes the first use of serial block-face scanning electron microscopy (SBF-SEM) for the study of P10 structure formation in AcMNPV-infected TN-368 cells, identifying the independent formation of cytoplasmic and nuclear P10 fibrous bodies. The use of 3D modelling of P10 highlighted an expanding nuclear “worm-like” feature and dynamic cytoplasmic structures. The cytoplasmic structures developed from thin angular fibrils that condensed to thicker fibrous structures, forming a peri-nuclear cage that remodelled over time to form a large polarised mass. The high-resolution 3D characterisation of P10 structures using SBF-SEM provided previously unparalleled data on P10 and suggests a possible mechanism in nuclear stability and then lysis. During these studies an intimate association was found between P10, electron dense spacers (EDS) and occlusion bodies. To determine whether P10 was essential for EDS formation and calyx formation, recombinant viruses absent of the p10 gene were observed using electron microscopy. These viruses confirmed EDS continues to form in the absence of P10, however, EDSs fail to associate with occlusion bodies, which result in a fragmented calyx. This indicates EDS may require the presence of P10 to associate with polyhedra and the production of an intact polyhedral envelope. This was supported from SBF-SEM of AcMNPV-infected cells that showed EDS completely encased the occlusion bodies, providing a mechanism for the role of EDS in calyx formation. This study provides new insights in to the structural features of P10 and its association with other virus structures, and establishes the functional requirement for p10 to be expressed to high levels. These results will contribute to the long running quest to understand this multifunctional protein.
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Doležal, Tomáš. "Rekonstrukce tvaru objektu založená na odezvě max(t,0)-pulsu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413154.
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This diploma thesis deals with a spatial imaging of targets using time-domain radar responses on the max(t,0) pulse. The problem is formulated for both perfectly electrically conductive and dielectric objects. The main aim of the thesis includes a code implementation calculating the profile functions of an unknown object from the mentioned time responses and a code for the subsequent reconstruction of an object in the MATLAB environment. A graphical user interface was created for testing purposes. The 3D probability function technique was used for the final reconstruction. The implemented technique achieves interesting results, which are presented in the final part of this thesis.
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Carbone, Anna Lisa. "Engineering and functional characterisation of pentameric concatenated (α4)₂(β2)₃ and (α4)₃(β2)₂ nicotinic acetylcholine receptors." Thesis, Oxford Brookes University, 2009. https://radar.brookes.ac.uk/radar/items/6b5c0ace-ecf1-488d-95e6-b112bd79e252/1/.
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Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that influence neurotransmitter release, hence constituting a key component of the physiological mechanisms of neuronal signalling. This thesis is concerned with the properties of the a4P2 nAChR, the most abundant nAChR in the brain, and the major contributor to the central effects of nicotine. The a4P2 nAChR is made up of five subunits, which in heterologous systems can assemble into at least two different stoichiometries: the high sensitivity (HS) (a4h(P2)3 stoichiometry and the low sensitivity (LS) (a4)3(p2)2 stoichiometry, which might both exist in native tissues. Despite the attractiveness of the a.4P2 nAChR as a target for therapeutic intervention, progress in the development of a4P2 nAChR-selective drugs has been slowed, partly because of the lack of stoichiometric-specific receptor models. This study presents a strategy to express homogenous populations of a4P2 nAChRs with fixed stoichiometry. By using standard molecular biological techniques, pentameric concatenated (a4)2(P2)3 and (a4)3(P2)2 nAChRs were engineered. These receptors were expressed in Xenopus laevis oocytes and functional studies showed that their functional properties resembled those of their non-linked counterparts. Subsequent site-directed mutagenesis in combination with functional analysis allowed the identification of the agonist-binding subunits in both concatamers. Concatenated receptors proved to be suitable for comparative studies of the effects of receptor mutation linked to autosomal dominant nocturnal frontal lobe epilepsy. Studies carried out on non-linked receptors, showed that the properties of the (a4)3(p2)2 stoichiometry were affected more markedly than those of the (a4)2(p2)3 stoichiometry. Insertion of the mutation in concatenated receptors revealed that the mutation not only affected the functional properties of a.4P2 nAChRs but also altered the subunit composition of the receptor. These studies show that pentameric concatenated constructs are a powerful tool to study the function and structure of receptors that assemble in multimeric types in expression systems.
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Feltekh, Kais. "Analyse spectrale des signaux chaotiques." Phd thesis, INSA de Toulouse, 2014. http://tel.archives-ouvertes.fr/tel-01071919.
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Au cours des deux dernières décennies, les signaux chaotiques ont été de plus en plus pris en compte dans les télécommunications, traitement du signal ou transmissions sécurisées. De nombreux articles ont été publiés qui étudient la densité spectrale de puissance (DSP) des signaux générés par des transformations spécifiques. La concentration sur la DSP est due à l'importance de la fréquence dans les télécommunications et la transmission sécurisée. Grâce au grand nombre de systèmes sans fil, la disponibilité des fréquences de transmission et de réception est de plus en plus rare pour les communications sans fil. Aussi, les médias guidés ont des limitations liées à la bande passante du signal. Dans cette thèse, nous étudions certaines propriétés associées à la bifurcation collision de frontière pour une transformation unidimensionnelle linéaire par morceaux avec trois pentes et deux paramètres. Nous calculons les expressions analytiques de l'autocorrélation et de la densité spectrale de puissance des signaux chaotiques générés par les transformations linéaires par morceaux. Nous montrons l'existence d'une forte relation entre les différents types de densité spectrale de puissance (passe-bas, passe-haut ou coupe-bande) et les paramètres de bifurcation. Nous notons également en évidence une relation entre le type de spectre et l'ordre des cycles attractifs. Le type du spectre dépend de l'existence des orbites périodiques au-delà de la bifurcation de collision de frontière qui a donné naissance au chaos. Nous utilisons ensuite les transformations chaotiques pour étudier la fonction d'ambiguïté. Nous combinons quelques transformations chaotiques bien déterminées pour obtenir un spectre large bande avec une bonne fonction d'ambiguïté qui peut être utilisée en système radar.
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Mazzaferro, Simone. "The emerging role of the α4(+)α4(-) interface as a determinant of functional signatures of α4ß2 nicotinic acetylcholine receptors." Thesis, Oxford Brookes University, 2013. https://radar.brookes.ac.uk/radar/items/b0ec8a36-031d-4c4d-b149-42d431fc795b/1/.
Full textAbstract:
The α4β2 nicotinic acetylcholine receptor (nAChR) assembles in two alternate forms, (α4β2)₂α4 and (α4β2)₂β2, which display stoichiometry-specific agonist sensitivity. Being heteromeric pentameric ligand-gated ion channels (pLGIC), α4β2 receptors are activated by binding of agonist to sites located at the α4(+)/β2(-) interfaces. These interfaces are present in both stoichiometries they are unlikely to contain structural differences conferring specific properties to (α4β2)₂α4 and (α4β2)₂β2 receptors. In contrast, the auxiliary subunit can be either α4 or β2, leading to stoichiometry-specific β2(+)/β2(-) and α4(+)/α4(-) interfaces. Using fully concatenated (α4β2)₂α4 nAChRs in conjunction with structural modelling, chimeric receptors and functional mutagenesis, this study identified an additional agonist site at the α4(+)/α4(-) interface that accounts for the stoichiometry-specific agonist sensitivity of the (α4β2)₂α4 receptor. The additional agonist site occupies a region that also contains a potentiating Zn²⁺ binding site. However, unlike Zn²⁺, the agonist binding influences agonist responses by directly contributing to channel gating. By engineering a receptor with a C226S mutation to provide a free cysteine in loop C in the + side of the α4(+)/α4(-) interface, this study found that the acetylcholine (ACh) responses of the additional agonist site are modified following modification of the substituted cysteine with sulfhydryl reagents. These findings suggested that agonist occupation of the site at the α4(+)/α4(-) interface leads to channel gating through a coupling mechanism involving a conformational switch in loop C. The sulfhydryl reagents had similar effects on substituted cysteines in the α4(+)/β2(-) interfaces. Further studies showed that the additional agonist site is less sensitive to desensitisation than the sites at the α4(+)/β2(-) interfaces, suggesting that the agonist sites are functionally non-equivalent. Non-functional equivalency was also indicated by the finding that the agonist selectivity of the site at the α4(+)/α4(-) differs from that of the sites at the α4(+)/β2(-) interface. The findings may have important consequences for drug discovery programs and the manner by which α4β2 receptor signalling in the brain can be modified in brain pathologies.
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Sambath, Praanesh. "Radar Target detection using Cell Evaluation Method for Industrial Safety." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286698.
Full textAbstract:
The main aim of using radars in industrial safety system is to detect the presence of target accurately. The conventional methods of radar target detection algorithm such as the Cell averaging constant false alarm rate method (CA-CFAR), Greatest of constant false alarm method (GO-CFAR) and the Smallest of constant false alarm rate method (SO-CFAR) has their own disadvantage when it comes to precise target detection which is a key factor for a safety system. This thesis investigates the above mentioned conventional CFAR algorithms for its pros and cons in target detection and proposes a new and improved method called Cell Evaluation target detection method. The proposed method is shown to mitigate the limitations present and the assumptions made in the conventional target detection method. Further more angular estimation is performed to determine the precise location of the target and the artifacts due to the angular estimation is eliminated by aggregating the detected points from multiple radar modules by linear translation. This gives a better visualization of the target.Radarteknik kan användas inom maskinsäkerhet (MS) för att detektera skyddsvärda objekt, typiskt människor i arbete nära maskiner. Konventionella metoder för detektering med given frekvens falsk alarm (eng. Constant False Alarm Rate (CFAR)) som baseras på medelvärden, har dock betydande brister. Främst beträffande precision och tillförlitlighet, vilket är centralt för MS. Exempel som studerats i detta examensarbete är “Cell-averaging CFAR” (CA-CFAR), “Greatest of CFAR” (GO-CFAR) samt “Smallest of CFAR” (SO-CFAR). Med målet att förbättra detektionen föreslås även en ny CFAR-metod, vilken benämns ”Cell Evaluation target detection”. I detta arbete visas denna metod undertrycka begränsningar med konventionella tekniker. Den undviker även en del antaganden som inte alltid stämmer i praktiken. Studien inkluderar även skattning av riktning. Det visas hur visualisering av skyddsobjekt kan förbättras, genom att felaktigheter elimineras efter sammanläggning av detektioner från flera radarmoduler efter koordinattransformation.