Siga este link para ver outros tipos de publicações sobre o tema: Radar theory.
Teses / dissertações sobre o tema "Radar theory"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Radar theory".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
1
Saddington, P. "Adaptive resonance theory : theory and application to synthetic aperture radar". Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/843249/.
Texto completo da fonteResumo:
Artificial Neural Networks are massively parallel systems that are constructed from many simple processing elements called neurons. The neurons are connected via weights. This structure is inspired by the current understanding of how biological networks function. Since the 1980s, research into this field has exploded into the hive of activity that currently surrounds neural networks and intelligent systems. The work in this thesis is concerned with one particular artificial neural network: Adaptive Resonance Theory (ART). It is an unsupervised neural network that attempts to solve the stability-plasticity dilemma. The model is, however, limited by a few serious problems that restrict its use in real life situations. The network's ability to cluster consistently with uncorrupt inputs when the input is subject to even modest amounts of noise is severely handicapped. The work detailed herein attempts to improve on ART's behaviour towards noisy inputs. Novel equations are developed and described that improve on the network's performance when the system is subject to noisy inputs. One of the novel equations affecting vigilance makes a significant improvement over the originators' equations and can cope with 16% target noise before results fall to the same values as the standard equation. The novel work is tested using a real-life (not simulated) data set from the MSTAR database. Synthetic Aperture Radar targets are clustered and then subject to noise before being represented to the network. These data simulate a typical environment where a clustering or classifying module would be needed for object recognition. Such a module could then be used in an Automatic Target Recognition (ATR) system. Once the problem is mitigated, Adaptive Resonance Theory neural networks could play important roles in ATR systems due to its lack of computational complexity and low memory requirements when compared with other clustering techniques. Keywords: Adaptive Resonance Theory, clustering consistency, neural network, automatic target recognition, noisy inputs.
2
Enders, Robert H. "Laser radar tracking theory : track-while-image operation". Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14424.
Texto completo da fonteResumo:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1989.Vita.
Includes bibliographical references.
Supported by U.S. Army Research Office. DAAL03-87-K-0117
by Robert Hay Enders.
Ph.D.
3
Kenny, Owen Patrick. "Theory of radar imaging using time-frequency distribution". Thesis, Queensland University of Technology, 1992. https://eprints.qut.edu.au/36211/6/36211_Digitised%20Thesis.pdf.
Texto completo da fonteResumo:
The concept of radar was developed for the estimation of the distance (range) and velocity of a target from a receiver. The distance measurement is obtained by
measuring the time taken for the transmitted signal to propagate to the target and return to the receiver. The target's velocity is determined by measuring the Doppler
induced frequency shift of the returned signal caused by the rate of change of the time- delay from the target. As researchers further developed conventional radar systems
it become apparent that additional information was contained in the backscattered signal and that this information could in fact be used to describe the shape of the target itself. It is due to the fact that a target can be considered to be a collection of individual point scatterers, each of which has its own velocity and time- delay. DelayDoppler parameter estimation of each of these point scatterers thus corresponds to a mapping of the target's range and cross range, thus producing an image of the target. Much research has been done in this area since the early radar imaging work of the 1960s. At present there are two main categories into which radar imaging falls. The
first of these is related to the case where the backscattered signal is considered to be deterministic. The second is related to the case where the backscattered signal is of a stochastic nature. In both cases the information which describes the target's scattering
function is extracted by the use of the ambiguity function, a function which correlates the backscattered signal in time and frequency with the transmitted signal. In practical situations, it is often necessary to have the transmitter and the receiver of the radar system sited at different locations. The problem in these situations is 'that a reference signal must then be present in order to calculate the ambiguity function. This causes an additional problem in that detailed phase information about the transmitted signal is then required at the receiver. It is this latter problem which has led to the investigation of radar imaging using time- frequency distributions. As will be shown in this thesis, the phase information about the transmitted signal can be extracted from the
backscattered signal using time- frequency distributions.
The principle aim of this thesis was in the development, and subsequent discussion into the theory of radar imaging, using time- frequency distributions. Consideration is
first given to the case where the target is diffuse, ie. where the backscattered signal has temporal stationarity and a spatially white power spectral density. The complementary situation is also investigated, ie. where the target is no longer diffuse, but some degree
of correlation exists between the time- frequency points. Computer simulations are presented to demonstrate the concepts and theories developed in the thesis. For the proposed radar system to be practically realisable, both the time- frequency distributions and the associated algorithms developed must be able to be implemented in a timely manner. For this reason an optical architecture is proposed. This architecture is specifically designed to obtain the required time and frequency resolution when using
laser radar imaging. The complex light amplitude distributions produced by this architecture have been computer simulated using an optical compiler.
4
Park, C. K. "Two dimensional interpolation for radar raster scan display". Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357191.
Texto completo da fonte
5
Yoho, Peter K. "Satellite scatterometers : calibration using a ground station and statistical measurement theory /". Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd306.pdf.
Texto completo da fonte
6
Kasebzadeh, Pedram. "Clutter Detection in Radar Applications". Thesis, Linköpings universitet, Institutionen för datavetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-171547.
Texto completo da fonteResumo:
Radars have been used for detection purposes in safety applications (i.e., blind spot detection radar in cars) extensively. The existing detection methods, however, are not flawless. So far, the main focus of these methods is on detecting an object based on its reflectiveness. In this thesis, the limitation of conventional methods are addressed, and alternative approaches are proposed. The main objective is to model/identify the noise with statistical and machine learning approaches as an alternative to conventional methods that focus on the object. The second objective is to improve the time efficiency of these methods. The data for this thesis contains measurements collected from radars at ABB AB, Sweden. These measurements reflect the received signal strength. These radars are meant to be used in safety applications, such as in industrial environments. Thus, the trade-off between accuracy and complexity of the algorithms is crucial. One way to ensure there is nothing but noise in the surveillance field of the radar is to model the noise only. A new input can then be compared to this model and be classified as noise or not noise (object). One-class classifiers can be employed to approach this problem as they only need noise for training; hence they have been one of the initial proposals in this thesis. Alternatively, binary classifiers are investigated to classify noise and object given a new input data. Moreover, a mathematical model for noise is computed using the Fourier series expansion. While the derived model holds useful information in itself, it can be used, e.g., for hypothesis testing purposes. Furthermore, to make the classification more time-efficient, dimension reduction methods are considered. Feature extraction has been performed for this purpose with the help of the derived noise model. In order to evaluate the performance of the considered methods, three different datasets have been formed. In the first dataset,
7
Lindsay, K. W. "Secondary radar, collision avoidance and ship-to-ship communication". Thesis, Liverpool John Moores University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332121.
Texto completo da fonte
8
Bachmann, Darren John. "A game theoretic analysis of adaptive radar jamming /". Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00002983.
Texto completo da fonte
9
Smyth, Timothy James. "Precipitation measurements in convective storms using multiparameter radar". Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363714.
Texto completo da fonte
10
Simms, Melissa Jean. "A Novel Approach to Target Scene Detection and Identification: Theory & Experiments". Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470327337.
Texto completo da fonte
11
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.
Texto completo da fonte
12
Elgayar, Saad M. "From Theory to Practice: Randomly Sampled Arrays for Passive Radar". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503304471335023.
Texto completo da fonte
13
Xu, Cuichun. "Statistical processing on radar, sonar, and optical signals /". View online ; access limited to URI, 2008. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3328735.
Texto completo da fonte
14
Gung, Tza-Jing. "Radar range profile simulation of isolated trees with radiative transfer theory". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36572.
Texto completo da fonte
15
Yeang, Chen-Pang. "Target identification theory for synthetic aperture radar images using physics-based signatures". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80603.
Texto completo da fonte
16
Vestberg, Marcus Erik. "A compatibilist computational theory of mind". Thesis, Oxford Brookes University, 2017. https://radar.brookes.ac.uk/radar/items/bf378e8f-abc3-47cd-9004-4efab56970c1/1/.
Texto completo da fonteResumo:
This thesis defends the idea that the mind is essentially computational, a position that has in recent decades come under attack by theories that focus on bodily action and that view the mind as a product of interaction with the world and not as a set of secluded processes in the brain. The most prominent of these is the contemporary criticism coming from enactivism, a theory that argues that cognition is born not from internal processes but from dynamic interactions between brain, body and world. The radical version of enactivism in particular seeks to reject the idea of representational content, a key part in the computational theory of mind. To this end I propose a Compatibilist Computational Theory of Mind. This compatibilist theory incorporates embodied and embedded elements of cognition and also supports a predictive theory of perception, while maintaining the core beliefs pertaining to brain-centric computationalism: That our cognition takes place in our brain, not in bonds between brain and world, and that cognition involves manipulation of mental representational content. While maintaining the position that a computational theory of mind is the best model we have for understanding how the mind works, this thesis also reviews the various flaws and problems that the position has had since its inception. Seeking to overcome these problems, as well as showing that computationalism is still perfectly compatible with contemporary action and prediction-based research in cognitive science, the thesis argues that by revising the theory in such a way that it can incorporate these new elements of cognition we arrive at a theory that is much stronger and more versatile than contemporary non-computational alternatives.
17
Cirineo, Tony. "Doppler Video Signal Conditioning, Theory of Operation". International Foundation for Telemetering, 1996. http://hdl.handle.net/10150/611417.
Texto completo da fonteResumo:
International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, CaliforniaThis paper describes some of the signal conditioning and processing circuits that were developed to reconstruct the doppler video signal from a radar receiver under test. The reconstructed doppler video signal is then digitized and put into a telemetry frame for transmission to a ground receiving station.
18
Dalevi, Mathias. "S-Band Antenna Array". Thesis, Uppsala University, Astronomy and Space Physics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126302.
Texto completo da fonteResumo:
This report presents concepts for a planar active electronically scanned antenna(AESA). The goal of the project was to devlop a low-weight, low profile, thin, S-band antenna with wide-scan angle capabilities. In the final concept the service aspects of the T/R-modules was also taken into acount in order to allow easy and fast replacements of these components. The antenna was designed and optimised using the commercial software Ansoft HFSS. A prototype of the antenna was constructed and later measured and verified. The final concept is a 2m×2m antenna with an estimated weight of around 320 kg, around 11 cm thick (where the thickness of the antenna element is 1.76 cm) and has a maximum scan angle range of more than 45 degrees (with <–10dB active reflection) in the frequency band 3–3.5 GHz.
19
McElwain, Thomas P. "L-estimators used in CFAR detection". Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/29199.
Texto completo da fonte
20
Cammenga, Zachary Andrew. "High Range Resolution Micro-Doppler Radar Theory and Its Application to Human Gait Classification". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1483438572645656.
Texto completo da fonte
21
Williams, Mary Moulton. "Radar cross-section data encoding based on parametric spectral estimation techniques". Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06162009-063346/.
Texto completo da fonte
22
Lee, Yong Joo. "The SME filter approach to multiple target tracking with false and missing measurements". Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/13756.
Texto completo da fonte
23
Dixon, Jason Herbert. "Pattern-theoretic automatic target recognition for infrared and laser radar data". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54404.
Texto completo da fonteResumo:
Pattern theory, a mathematical framework for representing knowledge of complex patterns developed by applied mathematician Ulf Grenander, has been shown to have potential uses in automatic target recognition (ATR). Prior research performed in the mid-1990s at Washington University in St. Louis resulted in ATR algorithms based on concepts in pattern theory for forward-looking infrared (FLIR) and laser radar (LADAR) imagery, but additional work was needed to create algorithms that could be implemented in real ATR systems. This was due to performance barriers and a lack of calibration between target models and real data. This work addresses some of these issues by exploring techniques that can be used to create practical pattern-theoretic ATR algorithms. This dissertation starts by reviewing the previous pattern-theoretic ATR research described above and discussing new results involving the unification of two previously separate outcomes of that research: multi-target detection/recognition and thermal state estimation in FLIR imagery. To improve the overall utility of pattern-theoretic ATR, the following areas are re-examined: 1) generalized diffusion processes to update target pose estimates and 2) the calibration of thermal models with FLIR target data. The final section of this dissertation analyzes the fundamental accuracy limits of target pose estimation under different sensor conditions, independent of the target detection/recognition algorithm employed. The Cramér-Rao lower bound (CRLB) is used to determine these accuracy limits.
24
Matzner, Shari. "Model-Based Information Extraction From Synthetic Aperture Radar Signals". PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/248.
Texto completo da fonteResumo:
Synthetic aperture radar (SAR) is a remote sensing technology for imaging areas of the earth's surface. SAR has been successfully used for monitoring characteristics of the natural environment such as land cover type and tree density. With the advent of higher resolution sensors, it is now theoretically possible to extract information about individual structures such as buildings from SAR imagery. This information could be used for disaster response and security-related intelligence. SAR has an advantage over other remote sensing technologies for these applications because SAR data can be collected during the night and in rainy or cloudy conditions. This research presents a model-based method for extracting information about a building -- its height and roof slope -- from a single SAR image. Other methods require multiple images or ancillary data from specialized sensors, making them less practical. The model-based method uses simulation to match a hypothesized building to an observed SAR image. The degree to which a simulation matches the observed data is measured by mutual information. The success of this method depends on the accuracy of the simulation and on the reliability of the mutual information similarity measure. Electromagnetic theory was applied to relate a building's physical characteristics to the features present in a SAR image. This understanding was used to quantify the precision of building information contained in SAR data, and to identify the inputs needed for accurate simulation. A new SAR simulation technique was developed to meet the accuracy and efficiency requirements of model-based information extraction. Mutual information, a concept from information theory, has become a standard for measuring the similarity between medical images. Its performance in the context of matching a simulation image to a SAR image was evaluated in this research, and it was found to perform well under certain conditions. The factors that affect its performance, and the model-based method overall, were found to include the size of the building and its orientation. Further refinements that expand the range of operational conditions for the method would lead to a practical tool for collecting information about buildings using SAR technology. This research was performed using SAR data from MIT-Lincoln Laboratory.
25
Sheppard, Louise. "How coaching supervisees help and hinder their supervision : a Grounded Theory study". Thesis, Oxford Brookes University, 2016. https://radar.brookes.ac.uk/radar/items/b622add5-7b08-44a1-be82-87a1ebbcf4be/1/.
Texto completo da fonteResumo:
Coaching supervision is an emerging profession with a need of developing its knowledge base. However, there is a lack of understanding of the supervision process from the coaching supervisees’ perspective, a crucial element without which issues and debates about coaching supervision are incomplete. Furthermore, although most of the professional bodies that represent coaches in the UK require coaches to have supervision, they do not provide clear guidelines on how supervisee’s can use supervision effectively. This study aims to fill that gap, providing empirical evidence on how supervisees can help and hinder their supervision. A qualitative study was conducted, based on semi-structured interviews with nineteen participants – twelve supervisees and seven supervisors to gather data about participants’ lived-in experiences of coaching supervision. Critical realist Grounded Theory was used to analyse the findings, to describe the underlying psychological and social structures that are a condition for valuable coaching supervision and to generate a framework for how supervisees can help and hinder their coaching supervision. The study contributes empirically based insight into the benefits of coaching supervision from the perspective of the supervisee and adds to debates on the outcomes of coaching supervision. New evidence is provided about how supervisees can inhibit and enable their learning as they mature. Findings suggest that supervisee maturation can follow three stages and that how the supervisee interacts with their supervisor is affected by the relative stage. The study also identified that fear, power relations and our natural desire for learning might explain the lived-in experiences of supervisees. It was argued that supervisees can gain further value from the supervision experience by overcoming fear and stepping into their authority in the relationship in order to enhance learning. The study contributes to supervision practice by providing the first framework for supervisee-led supervision with guidelines for supervisees and supervisors, new stages of maturity to enable supervisees to understand where they are in their developmental journeys and practical recommendations for professional bodies, coach training organisations, coaching providers and learning and development practitioners.
26
Sealey, Roger Derek. "An analysis of the impact of privatisation and deregulation on the UK bus and coach and port industries". Thesis, Oxford Brookes University, 2003. http://radar.brookes.ac.uk/radar/items/9aa104be-58e9-6050-7ef8-8485338233f6/1.
Texto completo da fonteResumo:
The main objectives of this dissertation are: (1) To analyse the pre and post privatisation and deregulation performance of two United Kingdom industries from the transport sector. (2) To analyse the earning and employment in these industries prior to deregulation and/or privatisation, and to examine what has happened to them after these changes. (3) To investigate any changes that have occurred in trade union density in these industries compared with what has happened in the rest of the economy. (4) To see if there was any evidence of rent sharing prior to privatisation and deregulation. If it did exist, did it continue after privatisation and deregulation, or was it substantially reduced or eliminated. The methodology of the dissertation is eclectic, so it examined these issues from a number of different perspectives, and its contribution to knowledge is incremental. In regard to the bus and coach industry in the newly competitive period following deregulation and privatisation, the major firms emerged almost solely through external rather than organic growth. This went against one of the main aims of privatisation, which was to create a competitive industry of many small-to-medium sized operations. Privatisation and deregulation also failed to stop the decline in passenger numbers, which was another objective of the programme. In the case of the UK ports, it is extremely difficult to conclude that the changing ownership constituted a significant factor in port performance and efficiency. Instead, factors such as geographical location and labour market deregulation seems to have had a greater influence on efficiency in the ports. That the measure of liberalisation most associated with privatisation, and that offered the most in terms of potential gains in efficiency, were those on which major concessions had to be made by the Government to win management support for the political process of privatisation. If managerial support for privatisation was absent then process was unlikely to occur. The underlying success of deregulation and privatisation in these industries has been in reducing the power of trade unions to obtain rent for their members, which was one of the main, if understated aims of the policy.
27
Matricardi, Elisabetta. "Performance Analysis of a Radar System Based on 5G Signals". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Encontre o texto completo da fonteResumo:
Poiché lo spettro sta diventando una risorsa sempre più scarsa, l'idea di riutilizzarlo per più di un'applicazione è interessante, in quanto può evitare il sottoutilizzo di risorse spettrali altrimenti allocate in modo permanente. Negli ultimi anni è stata introdotta una alternativa ai segnali radar, che consiste in forme d'onda OFDM generate digitalmente. Questa tesi ha come obiettivo quello di investigare le prestazioni di un segnale di comunicazione, il 5G NR, quando usato per scopi di sensing. Un sistema radar e un algoritmo di processing basato sull'elaborazione radar OFDM nel dominio delle frequenze sono stati implementati e integrati con un metodo di interpolazione per tenere conto delle sottoportanti nulle all'interno della griglia di risorse in trasmissione. Quindi, sono state eseguite simulazioni al calcolatore per valutare le prestazioni di stima della distanza e della velocità; si mostra che è possibile ottenere un errore basso di stima dei parametri del target anche per valori di SNR bassi. Inoltre, le forme d'onda 5G NR, grazie alla loro impressionante larghezza di banda, alla numerologia scalabile e alla robustezza contro il multipath, hanno dimostrato di funzionare bene anche nei canali con fading. Mediante l'ausilio delle curve ROC, viene illustrata la differenza delle prestazioni del radar quando vengono utilizzati due tipi di canali radio, ovvero il canale AWGN e il canale con multipath fading.
28
Mariussen, A. "A grounded theory of affiliate marketing performance measurement in the tourism and hospitality context". Thesis, Oxford Brookes University, 2012. http://radar.brookes.ac.uk/radar/items/907e34ff-7d07-51ea-18af-cdda2678bba4/1.
Texto completo da fonteResumo:
Although the measurement of offline and online marketing is extensively researched, the area of online performance measurement still presents a number of unaddressed gaps, such as fragmented research and predominance of practitioner-driven measurement approaches. With a focus on affiliate marketing in tourism and hospitality, this thesis addressed these gaps and evaluates the effectiveness of practitioner-led online performance assessment. More precisely, the study explores a potential shift in affiliate marketing measurement practices, and develops a theory of affiliate marketing performances measurement in tourism and hospitality. Relying on a grounded theory research strategy, the work undertakes qualitative analysis of 72 online forum discussions, 37 interviews and 40 questionnaires with the major affiliate marketing stakeholder groups from the tourism and hospitality industry - merchants, affiliates, affiliate networks and affiliate agencies. The findings of the thesis add value to both theory and practice. The theoretical contribution of the research is twofold. First, the work furthers the broader marketing theory and in particular the distribution and promotion literature by exploring an under-researched online marketing channel - affiliate marketing - that can be employed for both promotion and distribution purposes. The study provides a detailed description of an affiliate marketing ecosystem and defines the key affiliate marketing constructs. Second, the work contributes to the performance measurement research by developing a substantiative theory of affiliate marketing performance measurement in tourism and hospitality. From the practitioner perspective, the work brings value by proposing a change in existing performance measurement practices and offering a process-oriented model of performance measurement in affiliate marketing, which details the phases and steps that managers can undertake in assessing performance. To further the findings, future research can explore the applicability of the proposed model to other industry sectors and online channels, and can develop the proposed substantive theory to a formal theory by employing other research methods, for example case studies and action research.
29
Tameh, Eustace K. "The development and evaluation of a deterministic mixed cell propagation model based on radar cross-section theory". Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364890.
Texto completo da fonte
30
Khabou, Mohamed Ali. "Improving shared weight neural networks generalization using regularization theory and entropy maximization /". free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9953870.
Texto completo da fonte
31
Kellett, Daniel. "Random Sequence Encoding with OFDM for Covert Communication and Signal Reuse for LPI/LPD Radar: Theory & Experiments". Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501120348908255.
Texto completo da fonte
32
Tovey, Philip Noel. "The theory and practice of extended communion, with particular reference to parishes within the Anglican Diocese of Oxford". Thesis, Oxford Brookes University, 2006. https://radar.brookes.ac.uk/radar/items/2099a75e-9861-408b-9329-e2bac8986503/1/.
Texto completo da fonteResumo:
The Roman Catholic Church, the Methodist Church, and the Church of England recently introduced a service of 'extended communion',which is the distribution of previously consecrated elements by lay-people to congregations, in the absence of a priest This has been a highly controversial service, many theologians being against it, while at the same time policy-makers having to introduce the service. It is justified in part by reference to patristic precedent and to pastoral need, which raises significant theoretical questions about the relationship of theory and practice. This thesis analyzes the introduction of this service, particularly in relation to the changing context for the church, and the declining numbers of clergy. Policy-maker's assumptions are identified as hypotheses to test The research then conducts a small-scale qualitative research project in the Diocese of Oxford to uncover and evaluate significant issues in practice. This part of the thesis, tests the ten hypotheses previously identified, and discovers and evaluates the development oflocal theology, previous research not having included this level of theological debate. 32 interviews in six parishes were conducted, as well as observational research and documentary analysis. The research challenges the assumption that extended communion is primarily a rural phenomenon, and the evidence uncovered suggests that the principal usage is clergy cover, whatever the espoused theory. This gap between theory and practice is developed into a methodological debate about the relationship between empirical research and theological enquiry. A model is created which gives a priority to revelation, but acknowledges its interpretation as provisional, and allows a challenge to theology from empirical findings.
33
Norén, Gustav. "Noise Robustness of Convolutional Autoencoders and Neural Networks for LPI Radar Classification". Thesis, KTH, Matematisk statistik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-273604.
Texto completo da fonteResumo:
This study evaluates noise robustness of convolutional autoencoders and neural networks for classification of Low Probability of Intercept (LPI) radar modulation type. Specifically, a number of different neural network architectures are tested in four different synthetic noise environments. Tests in Gaussian noise show that performance is decreasing with decreasing Signal to Noise Ratio (SNR). Training a network on all SNRs in the dataset achieved a peak performance of 70.8 % at SNR=-6 dB with a denoising autoencoder and convolutional classifier setup. Tests indicate that the models have a difficult time generalizing to SNRs lower than what is provided in training data, performing roughly 10-20% worse than when those SNRs are included in the training data. If intermediate SNRs are removed from the training data the models can generalize and perform similarly to tests where, intermediate noise levels are included in the training data. When testing data is generated with different parameters to training data performance is underwhelming, with a peak performance of 22.0 % at SNR=-6 dB. The last tests done use telecom signals as additive noise instead of Gaussian noise. These tests are performed when the LPI and telecom signals appear at different frequencies. The models preform well on such cases with a peak performance of 80.3 % at an intermidiate noise level. This study also contribute with a different, and more realistic, way of generating data than what is prevalent in literature as well as a network that performs well without the need for signal preprocessing. Without preprocessing a peak performance of 64.9 % was achieved at SNR=-6 dB. It is customary to generate data such that each sample always includes the start of its signals period which increases performance by around 20 % across all tests. In a real application however it is not certain that the start of a received signal can be determined.Detta arbete studerar brustålighet hos neurala nätverk för klassificering av \textit{låg sannolikhet för avlyssning} (LPI) radars modulationstyp. Specifikt testas ett antal arkitekturer baserade på faltningsnätverk och evalueras i fyra olika syntetiska brusmiljöer. Tester genomförda på data med Gaussiskt brus visar att klasificeringsfelet är ökande med ett minskande signal-till-brusförhållande. Om man låter nätverken träna på alla brusnivåer som ingår i datan uppnås en högsta pricksäkerhet om 70.8 % vid ett signal-till-brusförhållande på -6 dB. Vidare tester tyder på att nätverken presterar sämre på låga signal-till-brusförhållanden om de inte finns med i träningsdata och ger i allmänhet mellan 10-20 % sämre pricksäkerhet. Om de mellersta brusnivåerna inte finns med i träningsdata presterar nätverken lika bra som när de finns med i träningsdata. Om träningsdata och testdata genereras med olika parameterar presterar nätverken dåligt. För dessa tester uppnås en högsta pricksäkerhet om 22.0 % vid ett signal-till-brusförhållande på -6 dB. Den sista brusmiljön som testades på använder sig av telekom signaler som om de vore brus istället för Gaussiskt brus. I detta fall är LPI och telekom signalerna väl skiljda i frekvens och nätverken presterar lika bra som tester i Gaussiskt brus med högt signal-till-brusförhållande. Högsta pricksäkerhet som uppnåts på dessa tester är 80.3 % i mellanhög brusnivå. Detta arbete bidrar även med nätverk som presterar bra utan att data behöver signalbehandlas innnan den kan klassificeras samt genererar data på ett mer realistiskt vis än tidigare litteratur inom detta område. Utan att signalbehandla data uppnåddes en högsta pricksäkerhet om 64.9 % vid ett signal-till-brusförhållande på -6 dB. Den mer realistiska datan genereras så att dess startpunkt är slumpmässig. I litteraturen brukar startpunkten inkluderas och uppnår på så vis överlag pricksäkerheter som är ungefär 20 % högre än de tester som genomförs i detta arbete. I verkliga applikationer är det sällan man kan identifera en signals startpunkt med säkerhet.
34
Benson, Stephen Ray. "Modern Digital Chirp Receiver: Theory, Design and System Integration". Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1450737245.
Texto completo da fonte
35
Comblet, Fabrice. "Détection, localisation et identification de cibles radar par imagerie électromagnétique bistatique". Phd thesis, Université de Bretagne occidentale - Brest, 2005. http://tel.archives-ouvertes.fr/tel-00011931.
Texto completo da fonteResumo:
L'objectif de cette thèse est de développer, caractériser et analyser l'imagerie radar en configuration bistatique. Dans le cadre de notre étude, nous nous plaçons dans le cas général d'une configuration bistatique sans condition sur la configuration d'acquisition. Nous avons alors développé un algorithme de reconstruction d'images tenant compte des polarisations d'émission et de réception. Ainsi, nous avons pu caractériser les images obtenues et donner l'expression des résolutions d'une image bistatique en fonction de la configuration d'acquisition. Ensuite, nous avons étudié les images bistatiques reconstruites lors de l'observation de cibles complexes ainsi que celles obtenues lors de la détection de cibles sur une surface océanique afin de les comparer avec celles d'une configuration monostatique. Les résultats ainsi obtenus permettent de valider l'intérêt de la configuration bistatique et de présenter les nouvelles perspectives qu'offre ce sujet de recherche en imagerie radar.
36
Zietsman, Christian Frederick. "Theory, design and implementation of an IF cancellation module for use in a stepped frequency continuous wave ground penetrating radar". Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/14972.
Texto completo da fonteResumo:
Bibliography: leaves 64-68.A device has been designed that cancels the leakage signal between the transmit and receive antenna in a Stepped Frequency Continuous Wave Ground Penetrating Radar. The front end of the radar operates at high signal levels and, as a result, a large signal is coupled directly from the transmit to the receive antenna. This signal uses a signiï¬ cant part of the dynamic range of the data-capturing device, an analogue-to-digital converter (ADC). The objective of this cancellation is thus to increase the effective instantaneous dynamic range of the radar system. Simulations show that 10-bit amplitude and phase resolution in the digital cancellation circuit would achieve maximum cancellation in the presence of phase noise and other sources of error. This result is conï¬ rmed when the hardware is tested. The device was constructed and operates as intended. Tests show that cancellation exceeding 53dBm is possible through careful calibration. It was concluded that the device could successfully be integrated into the SFCW GPR and that it would achieve an increase in the instantaneous dynamic range.
37
Chéty, Laurent. "Diffraction d'ondes electromagnetiques par des objets de forme et de nature arbitraires : etude de faisabilite d'une representation integrale". Paris 6, 1988. http://www.theses.fr/1988PA066144.
Texto completo da fonteResumo:
La finalite de ce travail est la modelisation de l'interaction d'une onde electromagnetique plane en regime harmonique avec des composantes simples d'une cible complexe. Ceci dans le but de caracteriser soit la contribution de chaque element de la structure au champ diffracte, soit le couplage entre elements distincts. Une application particuliere concerne la surface equivalente radar, monostastique et bistatique, de ces structures. L'utilisation d'equations integrales de surface permet d'obtenir les courants electrique et magnetique induits par l'onde incidente. Ces equations integrales sont resolues numeriquement par la methode des moments, pour laquelle la surface des objets, de forme quelconque, est modelisee par des triangles plans. Plusieurs types d'objet sont etudies avec cette methode
38
Casbeer, David W. "Decentralized Estimation Using Information Consensus Filters with a Multi-static UAV Radar Tracking System". Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2779.pdf.
Texto completo da fonte
39
Borderieux, Sylvain. "Apport de la théorie de l’information quantique dans la perspective du radar quantique". Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0011.
Texto completo da fonteResumo:
Cette thèse propose une approche originale de la thématique du radar à illumination quantique en recourant à la théorie de l’information quantique pour étudier l’évolution des corrélations quantiques le long d’une chaîne radar. Ce mémoire propose d’abord un parallèle des différences et similitudes entre les théories du radar classique et du radar quantique en insistant sur les principes propres aux deux théories. Le radar à illumination quantique étudié utilise des paires de photons intriqués pour établir la présence ou l’absence d’un objet faiblement réfléchissant baigné dans un bruit thermique parasitant la détection. À partir de la mise en parallèle, les travaux se sont concentrés sur l’influence de l’environnement atmosphérique dans l’évolution de l’intrication du système de photons du radar et dans l’évolution des corrélations quantiques représentées par la discorde quantique. L’objectif des recherches était de montrer un lien entre la discorde quantique et la stratégie de détection binaire du radar quantique. Les résultats tendent à montrer ce lien même si des améliorations aux modèles composés pour l’étude seraient bienvenues. Cela permettrait notamment d’orienter la recherche vers des cas concrets pouvant bénéficier d’une application expérimentale du procédé d’illumination quantiqueThis thesis provides an original approach of the quantum illumination radar using the quantum information theory to study the evolution of quantum correlations in a radar system. We first propose a parallel between the classical radar theory and the quantum radar theory to determine similarities anf differences insisting on the last point. The quantum illumination radar uses pairs of entangled photons to detect the absence of the presence of a low-reflecting object into a bright thermal background that disturbs the detection. Using the parallel between the radar theories, research has been done on the atmospheric influence on the evolution of entanglement of the system of photons in the radar, and on the evolution of quantum correlations quantified by the quantum discord. The objective of research was to show a link between the quantum discord and the binary decision strategy of the quantum radar. Results suggest this link even if improvements should be required on the tested models. It should permit to study practical situations particularly if we think about a possible experiment on a quantum illumination protocol
40
Elghannai, Ezdeen Ahmed. "NOVEL METHOD TO CONTROL ANTENNA CURRENTS BASED ON THEORY OF CHARACTERISTIC MODES". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471871173.
Texto completo da fonte
41
Cetin, Aysin. "Cfar Detection In K-distrbuted Sea Clutter". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609857/index.pdf.
Texto completo da fonteResumo:
Conventional fixed threshold detectors set a fixed threshold based on the overall
statistical characteristics of the spatially uniform clutter over all ranges to give a
specific probability of false alarm and detection. However, in radar applications
clutter statistics are not known a priori. Constant False Alarm Rate (CFAR)
techniques provide an adaptive threshold to estimate the clutter statistics and to
distinguish targets from clutter. In Cell Averaging CFAR (CA-CFAR) the
threshold is controlled by averaging the fixed size CFAR cells surrounding the cell
under test.
In this thesis, radar detection of targets in sea clutter modelled by compound Kdistribution
is examined from a statistical detection viewpoint by Monte Carlo
simulations. The performance of CA-CFAR processors is analysed under varying
conditions of sea clutter spatial correlation and spikiness for several cases of false
alarm probability, the length of cell size used in the CFAR processor and the
number of pulses integrated prior to CA-CFAR processor.
v
The detection performance of CA-CFAR is compared with the performance of
fixed threshold detection. The performance evaluations are quantified by CFAR
loss. CFAR loss is defined as the increase in average signal to clutter ratio
compared to that of fixed threshold, required to achieve a given probability of
detection and probability of false alarm. Curves for CFAR loss to the spikiness and
spatial correlation of clutter, number of pulses integrated and the length of cell size
are presented.
42
Yang, Le. "Médianes de mesures de probabilité dans les variétés riemanniennes et applications à la détection de cibles radar". Phd thesis, Université de Poitiers, 2011. http://tel.archives-ouvertes.fr/tel-00664188.
Texto completo da fonteResumo:
Dans cette thèse, nous étudierons les médianes d'une mesure de probabilité dans une variété riemannienne. Dans un premier temps, l'existence et l'unicité des médianes locales seront montrées. Afin de calculer les médianes aux cas pratiques, nous proposerons aussi un algorithme de sous-gradient et prouverons sa convergence. Ensuite, les médianes de Fréchet seront étudiées. Nous montrerons leur cohérence statistique et donnerons des estimations quantitatives de leur robustesse à l'aide de courbures. De plus, nous montrerons que, dans les variétés riemanniennes compactes, les médianes de Fréchet de données génériques sont toujours uniques. Des algorithmes stochastiques et déterministes seront proposés pour calculer les p-moyennes de Fréchet dans les variétés riemanniennes. Un lien entre les médianes et les problèmes de points fixes sera aussi montré. Finalement, nous appliquerons les médiane et la géométrie riemannienne des matrices de covariance Toeplitz à la détection de cible radar.
43
Ertug, Ozgur. "Generalized Random Spreading Performance Analysis Of Cdma Over Gwssus Fading Channels". Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12607022/index.pdf.
Texto completo da fonteResumo:
Since direct-sequence code-division multiple-access
(DS-CDMA) is an interference-limited random multiple-access
scheme, the reduction of co-channel interference with either
interference suppression or interference cancellation multiuser
receivers and/or power control to prevent detrimental near-far
situations is vital for improved performance. Up to date, some
contributions investigated randomly-spread asymptotically - large
number of users and large bandwidth - large CDMA systems with
multiuser receivers and power control via random matrix theoretic
and free probability theoretic tools especially over Gaussian and
single-path fading channels. As complement within this thesis, we
analyze also within the generalized random spreading framework but
at finite system sizes and without power control the capacity
achievable with linear multichannel multiuser receiversi.e. RAKE, zero-forcing decorrelator, linear minimum mean-squared error (LMMSE) multiuser receivers, within a single-cell setting over generalized time-varying GWSSUS - Rayleigh/Ricean - fading channels via random matrix theoretic tools. Assuming maximal-ratio combining (MRC) of resolved frequency - multipath - diversity channels due to wideband transmission, the signal-to-interference ratios (SIRs) with multichannel multiuser receivers that set the basis for further derivations are statistically characterized. The information-theoretic ergodic and outage sum-rates spectral efficiencies are then derived and analyzed.
44
Jdey, Aloui Imen. "Contribution des techniques de fusion et de classification des images au processus d'aide à la reconnaissance des cibles radar non coopératives". Thesis, Brest, 2014. http://www.theses.fr/2014BRES0008.
Texto completo da fonteResumo:
La reconnaissance automatique de cibles non coopératives est d’une grande importance dans divers domaines. C’est le cas pour les applications en environnement incertain aérien et maritime. Il s’avère donc nécessaire d’introduire des méthodes originales pour le traitement et l’identification des cibles radar. C’est dans ce contexte que s’inscrit notre travail. La méthodologie proposée est fondée sur le processus d’extraction de connaissance à partir de données (ECD) pour l’élaboration d’une chaine complète de reconnaissance à partir des images radar en essayant d’optimiser chaque étape de cette chaine de traitement. Les expérimentations réalisées pour constituer une base de données d’images ISAR ont été effectuées dans la chambre anéchoïque de l’ENSTA de Bretagne. Ce dispositif de mesures utilisé a l’avantage de disposer d’une maîtrise de la qualité des données représentants les entrées dans le processus de reconnaissance (ECD). Nous avons ainsi étudié les étapes composites de ce processus de l’acquisition jusqu’à l’interprétation et l’évaluation de résultats de reconnaissance. En particulier, nous nous sommes concentrés sur l’étape centrale dédiée à la fouille de données considérée comme le cœur du processus développé. Cette étape est composée de deux phases principales : une porte sur la classification et l’autre sur la fusion des résultats des classifieurs, cette dernière est nommée fusion décisionnelle. Dans ce cadre, nous avons montré que cette dernière phase joue un rôle important dans l’amélioration des résultats pour la prise de décision tout en prenant en compte les imperfections liées aux données radar, notamment l’incertitude et l’imprécision. Les résultats obtenus en utilisant d’une part les différentes techniques de classification (kppv, SVM et PMC), et d’autre part celles de de fusion décisionnelle (Bayes, vote, théorie de croyance, fusion floue) font l’objet d’une étude analytique et comparative en termes de performancesThe automatic recognition of non-cooperative targets is very important in various fields. This is the case for applications in aviation and maritime uncertain environment. Therefore, it’s necessary to introduce innovative methods for radar targets treatment and identification.The proposed methodology is based on the Knowledge Discovery from Data process (KDD) for a complete chain development of radar images recognition by trying to optimize every step of the processing chain.The experimental system used is based on an ISAR image acquisition system in the anechoic chamber of ENSTA Bretagne. This system has allowed controlling the quality of the entries in the recognition process (KDD). We studied the stages of the composite system from acquisition to interpretation and evaluation of results. We focused on the center stage; data mining considered as the heart of the system. This step is composed of two main phases: classification and the results of classifiers combination called decisional fusion. We have shown that this last phase improves results for decision making by taking into account the imperfections related to radar data, including uncertainty and imprecision.The results across different classification techniques as a first step (kNN, SVM and MCP) and decision fusion in a second time (Bayes, majority vote, belief theory, fuzzy fusion) are subject of an analytical and comparative study in terms of performance
45
Skånfors, Lovisa. "Barns sociala vardagsliv i förskolan". Doctoral thesis, Karlstads universitet, Institutionen för pedagogiska studier, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-28622.
Texto completo da fonteResumo:
The overarching aim of the studies in this dissertation is to contribute knowledge about children’s shared social knowledge in their preschool peer cultures, regarding both content and how it is established and maintained. An ethnographic approach has been used to study the shared activities of children, aged 3-5, in the preschool. During 1 ½ years, one preschool setting was visited on a regular basis. One hundred hours of observation have been made and documented through video camera recordings and field notes. The theory of children’s peer cultures (Corsaro, 2005), positioning theory (Harré & Langenhove, 1999a) and social representation theory (Moscovici, 2001) have been used as theoretical tools in the analyses. The empirical results are presented in four articles (articles I-IV) and are all illustrations of the children’s shared social knowledge. The findings are that children’s shared social knowledge involves two main aspects of knowledge about relations; how to establish and maintain relations vis-à-vis various tokens or social resources (articles III and IV), and how to create distance to relations (articles I and II). Another find is that there seems to be a tension between the children’s social knowledge and the social norms explicitly formulated in the studied preschool context.I den här avhandlingen undersöker Lovisa Skånfors barns sociala vardagsliv i förskolan. Det specifika syftet är att bidra med kunskap om barns gemensamma sociala kunskaper i förskolans kamratkulturer, både vad gäller dess innehåll och hur de etableras och upprätthålls. Författaren har genom ett etnografiskt arbetssätt följt barns gemensamma aktiviteter på en 3-5-årsavdelning i en svensk förskola, under 1,5 år. Resultatet visar att barns gemensamma sociala kunskaper handlar om hur man kan skapa och upprätthålla relationer och hur man kan distansera sig från relationer. Barns sociala relationer skapas och upprätthålls i relation till olika sociala resurser (rätt ålder, specifika kompetenser och tidigare etablerade relationer). Barn skapar dessutom distans till andra barn och vuxna genom att på olika sätt dra sig undan i förskolekontexten. Resultatet visar också att det tycks finnas en spänning mellan barnens gemensamma sociala kunskaper och de normer om kollektivitet som explicit formuleras i den studerade förskolekontexten. Avhandlingen vänder sig till forskare och praktiker med intresse för frågor kring förskola och förskolebarns sociala samspel.
46
Tran, Nguyen Duy. "Performance bounds in terms of estimation and resolution and applications in array processing". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00777503.
Texto completo da fonteResumo:
This manuscript concerns the performance analysis in signal processing and consists into two parts : First, we study the lower bounds in characterizing and predicting the estimation performance in terms of mean square error (MSE). The lower bounds on the MSE give the minimum variance that an estimator can expect to achieve and it can be divided into two categories depending on the parameter assumption: the so-called deterministic bounds dealing with the deterministic unknown parameters, and the so-called Bayesian bounds dealing with the random unknown parameter. Particularly, we derive the closed-form expressions of the lower bounds for two applications in two different fields: (i) The first one is the target localization using the multiple-input multiple-output (MIMO) radar in which we derive the lower bounds in the contexts with and without modeling errors, respectively. (ii) The other one is the pulse phase estimation of X-ray pulsars which is a potential solution for autonomous deep space navigation. In this application, we show the potential universality of lower bounds to tackle problems with parameterized probability density function (pdf) different from classical Gaussian pdf since in X-ray pulse phase estimation, observations are modeled with a Poisson distribution. Second, we study the statistical resolution limit (SRL) which is the minimal distance in terms of the parameter of interest between two signals allowing to correctly separate/estimate the parameters of interest. More precisely, we derive the SRL in two contexts: array processing and MIMO radar by using two approaches based on the estimation theory and information theory. We also present in this thesis the usefulness of SRL in optimizing the array system.
47
Mahmod, Shad. "Deinterleaving pulse trains with DBSCAN and FART". Thesis, Uppsala universitet, Avdelningen för systemteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-379718.
Texto completo da fonteResumo:
Studying radar pulses and looking for certain patterns is critical in order to assess the threat level of the environment around an antenna. In order to study the electromagnetic pulses emitted from a certain radar, one must first register and identify these pulses. Usually there are several active transmitters in anenvironment and an antenna will register pulses from various sources. In order to study the different pulse trains, the registered pulses first have to be sorted sothat all pulses that are transmitted from one source are grouped together. This project aims to solve this problem, using Density-Based Spatial Clustering of Applications with Noise (DBSCAN) and compare the results with those obtained by Fuzzy Adaptive Resonance Theory (FART). We aim to further dig into these methods and map out how factors such as feature selection and training time affects the results. A solution based on the DBSCAN method is proposed which allows online clustering of new points introduced to the system. The methods are implemented and tested on simulated data. The data consists of pulse trains from simulated transmitters with unique behaviors. The deployed methods are then tested varying the parameters of the models as well as the number of pulse trains they are asked to deinterleave. The results when applying the models are then evaluated using the adjusted Rand index (ARI). The results indicate that in most cases using all possible data (in this case the angle of arrival, radio frequency, pulse width and amplitudes of the pulses) generate the best results. Rescaling the data further improves the result and tuning the parameters shows that the models work well when increasing the number of emitters. The results also indicate that the DBSCAN method can be used to get accurate estimates of the number of emitters transmitting. The online DBSCAN generates a higher ARI than FART on the simulated data set but has a higher worst case computational cost.
48
Cevik, Gozde. "Feature Based Modulation Recognition For Intrapulse Modulations". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607676/index.pdf.
Texto completo da fonteResumo:
In this thesis study, a new method for automatic recognition of intrapulse modulations has been proposed. This new method deals the problem of modulation recognition with a feature-based approach.
The features used to recognize the modulation type are Instantaneous Frequency, Instantaneous Bandwidth, Amplitude Modulation Depth, Box Dimension and Information Dimension. Instantaneous Bandwidth and Instantaneous Frequency features are extracted via Autoregressive Spectrum Modeling. Amplitude Modulation Depth is used to express the depth of amplitude change on the signal. The other features, Box Dimension and Information Dimension, are extracted using Fractal Theory in order to classify the modulations on signals depending on their shapes. A modulation database is used in association with Fractal Theory to decide on the modulation type of the analyzed signal, by means of a distance metric among fractal dimensions. Utilizing these features in a hierarchical flow, the new modulation recognition method is achieved.
The proposed method has been tested for various intrapulse modulation types. It has been observed that the method has acceptably good performance even for low SNR cases and for signals with small PW.
49
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.
Texto completo da fonteResumo:
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.
50
GERMOND, ANNE-LAURE. "Theorie de la polarimetrie radar bistatique". Nantes, 1999. http://www.theses.fr/1999NANT2008.
Texto completo da fonteResumo:
Le travail effectue propose une extension de la theorie de la polarimetrie radar, elaboree pour des systemes de mesures monostatiques, vers une theorie applicable a des systemes de mesures bistatiques. L'objectif de cette etude est de fournir des outils permettant de decrire les cibles dans le but de les caracteriser, de les classifier, voire de les identifier. Toute cible peut etre consideree, suivant sa structure, comme un modificateur plus ou moins fort de l'etat de polarisation de l'onde emise, vis-a-vis de l'onde diffusee. Elle est modelisee par une matrice, appelee matrice de diffusion. La volonte de detecter des cibles dites furtives accroit l'interet de mesurer la polarisation de l'onde diffusee, car ces cibles depolarisent generalement fortement et ne sont pas reperables par des radars scalaires. De plus, certaines cibles ne diffusent qu'un speculaire dans la direction de propagation-avant et seul un radar en configuration bistatique pourra les detecter. L'approche choisie pour fonder la theorie de la polarimetrie radar repose sur la decomposition de la matrice de diffusion bistatique en la somme d'une matrice symetrique et d'une matrice antisymetrique. La matrice symetrique permet de conserver les proprietes du cas monostatique, alors que la matrice antisymetrique denote le caractere purement bistatique de la configuration du systeme de mesures. Dans notre etude, nous nous sommes inspires de la demarche proposee par j. R. Huynen lors de l'elaboration de la theorie de la polarimetrie radar monostatique. Nous avons defini sept nouveaux parametres bistatiques fonction des elements de la matrice de diffusion bistatique. Ils viennent s'ajouter aux neuf parametres de huynen dependant de la partie symetrique. Ces seize parametres permettent alors de specifier la matrice de kennaugh. Cinq nouvelles equations de cibles bistatiques ont ete etablies, leur nombre total s'elevant ainsi a neuf. Ces neuf relations independantes, liant entre eux les seize parametres bistatiques, se construisent directement a l'aide du diagramme structurel bistatique d'une cible, appele aussi berlingot, que nous avons defini. Quatorze etats de polarisation caracteristiques de la cible sont proposes et leurs vecteurs de jones sont determines. Les positions relatives de ces points, visualisees sur la sphere de poincare, forment la fourchette de polarisation bistatique qui est geometriquement definie par six angles. Ces angles constituent, avec la puissance maximale copolarisee liee au rayon de la sphere de poincare, les parametres d'euler bistatiques. Une premiere approche de l'etude phenomenologique bistatique, reposant sur differentes cibles canoniques, est presentee. Les evolutions des seize parametres bistatiques suivant differentes configurations sont visualisees. Enfin, dans l'hypothese d'une mise en oeuvre d'une campagne de mesures bistatiques et polarimetriques de cibles, plusieurs methodes de calibration bistatiques sont presentees.