Dissertations / Theses on the topic 'NOx detection'
To see the other types of publications on this topic, follow the link: NOx detection.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'NOx detection.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Gao, Jing. "Etude et mise au point d'un capteur de gaz pour la detection sélective de NOx en pot d'échappement automobile." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2011. http://tel.archives-ouvertes.fr/tel-01016361.
Full textAbstract:
Afin de contrôler l'émission totale des NOx dans l'échappement automobile, un capteur potentiométrique à base de zircone stabilisée à l'yttrium a été développé par la technique de sérigraphie. Il est montré que l'utilisation d'un filtre catalytique, déposé directement sur l'élément sensible, permet d'éliminer les interférences venant d'autres gaz réducteurs dans l'échappement, en particulier monoxyde de carbone (CO), hydrogène (H2), hydrocarbures (CxHy) et ammoniac (NH3). En plus, il est possible de fixer avec le filtre catalytique le rapport NO/NO2 correspondant à l'équilibre thermodynamique. Par conséquent la réponse du capteur n'est plus dépendante du rapport NO/NO2, mais seulement de la température. De plus, la sensibilité et la sélectivité du capteur à NO2 peut considérablement être améliorée en appliquant un courant de polarisation.
2
VIGNA, LORENZO. "Chemiresistive devices for room-temperature gas sensing applications: from loaded and intrinsically conductive polymers to layered double hydroxides." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2967017.
Full text
3
Romanytsia, Ivan. "Etude des propriétés électro-catalytiques des matériaux d’électrode et des phénomènes de polarisation pour la compréhension des mécanismes de détection d'un capteur d'oxydes d'azote et l'optimisation de son fonctionnement." Thesis, Saint-Etienne, EMSE, 2014. http://www.theses.fr/2014EMSE0760.
Full textAbstract:
Le transport routier est responsable de la production de la majeure partie des oxydes d’azote (NOx) émis dans l’atmosphère. La majorité de cette pollution est donc concentrée dans des zones très urbanisées. L’exposition permanente aux gaz d’échappement a des conséquences graves pour la santé humaine et pour cela, des normes d’émission de plus en plus strictes sont mises en place. Les technologies post-Traitement embarquées dans les pots d’échappement sont de plus en plus complexes et nécessitent un control continu de la composition gazeuse. Les conditions sérères de ce milieu requièrent le développement de capteurs de gaz robustes et de longue durée de vie. Dans ce travail, nous présentons la procédure de fabrication et la caractérisation d’un capteur électrochimique à trois électrodes pouvant satisfaire les exigences d’une application industrielle dans le domaine automobile. La technologie de sérigraphie utilisée a l’avantage d’être facilement transférable dans l’industrie pour une production de masse bas cout.Le principe de fonctionnement du capteur est basé sur la polarisation galvanostatique de l’électrode sensible permettant une détection sélective de NO2 sans interférence avec d’autres gaz comme CO et NO. De plus, afin d’augmenter la stabilité du capteur, de diminuer les temps de réponse et de recouvrement, un nouveau matériau d’électrode composite à base d’or a été développé.Enfin, la réduction électrochimique de l’oxygène sur l’or et sur des électrodes composite a été étudiée, afin de proposer un mécanisme de détection de NO2Road transport is one of the main sources of NOx emitted into the atmosphere. The majority of this pollution is concentrated in urbanized areas. The permanent exposure to the exhaust gases has serious consequences for human health and for that, emission standards become more stringent. The modern technologies present in automotive need the continuous control of the exhaust composition. The variations of temperature, composition of exhaust gas, vibrations and other factors require long life robust control systems. In this work, we present the procedure of fabrication and characterization of an electrochemical sensor with three electrodes that can fulfill the demands of industrial applications in automotive industry. Manufacturing by screen-Printing technology allows producing low-Cost sensor with high reproducibility in industrial process.The principle of our sensor is based on galvanostatic polarization of a gold sensing electrode allowing the selective detection of NO2 without interference to other gases such as CO and NO. In order to increase stability, and to decrease the response and recovery time of the sensor, a new Au composite sensitive electrode was developed. The electrochemical reduction of oxygen on gold and gold-Based electrodes was then studied, to propose a detailed mechanism of NO2 detection
4
Ru, Jifeng. "Adaptive estimation and detection techniques with applications." ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,285.
Full textAbstract:
Thesis (Ph. D.)--University of New Orleans, 2005.Title from electronic submission form. "A dissertation ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering and Applied Science"--Dissertation t.p. Vita. Includes bibliographical references.
5
Storozhenko, V. A., A. V. Myagkiy, and R. P. Orel. "Filtering of interference of inhomogeneous regular structure in thermal non-destructive control of cellular structures." Thesis, Eskisehir technical university, 2021. https://openarchive.nure.ua/handle/document/18954.
Full textAbstract:
Honeycomb constructions are the most widely used materials in contemporary aviation and space technology. They are the basis for the housings of practically all products of this sector, where reliability of all parts should meet the in-creased requirements. Special attention is paid to the quality of composite materials and to the absence of defects such as the places of adhesion failure (exfoliation) between the skin and the honeycomb filler. Therefore, increase in the efficiency and reliability of thermal flaw detection, based on in-depth analysis of the processes of detecting defects and development of the principles of optimization of both the procedure of control and subsequent processing of the obtained information, is an important and relevant task.
6
Makrakis, Dimitrios. "Generalized non-coherent detection." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6789.
Full textAbstract:
The objective of this thesis is to introduce new power efficient non-coherent receiver structures for linear (Quadrature Amplitude Modulated and Phase Shift Keyed) as well as Continuous Phase Modulated signals. A generalized non-coherent detection theory, addressing single or multi-amplitude/phase signals as well as operation in time dispersive channels has been developed. Structures of optimal non-coherent sequence estimators and symbol-by-symbol receivers are proposed. The analysis carried out provides the relation and link between existing non-coherent receivers and the optimal non-coherent detection concept. Using the framework set by the generalized non-coherent detection theory and applying approximations and reasonable simplifications wherever needed, we were able to propose new families of powerful, yet simple non-coherent receivers. Such receivers are the: (1) Block Decoders for PSK and CPM signals. They process the received signal information in a block form. Evaluation of them in both ideal and time dispersive channels has verified considerable gains (as compared to conventional differential receivers), especially when used with trellis coded schemes. The evaluation results have indicated improvements higher than 3 dB when the operation takes place in a Gaussian channel. In a faded channel, the results have shown improvements higher than 7 dB and a reduction in error floors close to one order of magnitude. (2) Asymptotically optimal decoders for a time dispersive channel and/or multi-amplitude/phase signals. They have been able to considerably improve the system's performance. When evaluated for uncoded and coded schemes they demonstrated excellent performance. Compared to the conventional differential receiver the results demonstrated improvements in excess of 5 dB. With the introduction of these receivers the extension of non-coherent technology to the power and bandwidth efficient family of the multi-amplitude/phase signals has been made possible. (3) Combined Squared Envelope and Multiple Differential Detection (recursive) Algorithms. They process the information provided by the use of a squared envelope and more than one (multiple) differential receivers in a recursive form. When evaluated with various linear and CPM signals they demonstrated considerable improvements. For white Gaussian noise channels, they achieved gains higher than 9 dB (compared to the conventional differential receiver). In a faded channel they were able to reduce the error floors by more than three orders of magnitude. (4) Symbol-by-symbol receivers based on phase correction and signal combining controlled by decision feedback. These receivers achieve their improvements by applying partial (decision directed) intersymbol interference (ISI) cancellation from the phase of the signal and by combining the outputs of more than one differential detector according to the decisions made regarding previous symbols. Evaluations have demonstrated improvements higher than 5 dB. In all of the above proposed receivers, a particular emphasis has been put on the simplicity factor. Possible efficient implementation scenarios of the receivers using today's digital signal processing technology are discussed in various parts of the present work. To evaluate the proposed schemes, an analytical framework has been developed. It covers evaluation in AWGN (ideal or time dispersive) as well as faded channels. Through this analysis, new distance expressions (equivalent to the Euclidean distance we encounter in coherent systems) which characterize the performance of the proposed non-coherent receivers have been identified. These distance metrics can be used for the design of improved coded schemes, developed to "match" the characteristics and operation principles of the proposed non-coherent receivers.
7
Morrow, David John. "Non-enzymatic electrochemical glucose detection." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317087.
Full text
8
Hill, Helena Anne. "Non cultural detection of Campylobacter." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247366.
Full text
9
Frazer, Gordon John. "Aspects of time-varying non Gaussian non-linear signal analysis." Thesis, Queensland University of Technology, 1996. https://eprints.qut.edu.au/105546/1/T%28BE%26E%29%201032%20Aspects%20of%20time-varying%20non-Gaussian%20non-linear%20signal%20analysis.pdf.
Full textAbstract:
This thesis addresses problems in the field of time-varying, non-Gaussian, non-linear signal processing. It concentrates on developing results in the areas of time-frequency signal analysis and higher-order spectra which are linked by the developing area of time-varying higher-order spectra. Motivation comes from applying procedures developed to underwater acoustic signals. Reviews of time-frequency analysis and higher-order spectra precede the research contributions. Three appendices cover: a review of the
multiple-window spectrum estimation method, an improved procedure for computing analytic signals frequently used in time-frequency signal analysis, and an updated approach for computing Slepian sequences necessary for the multiple-window spectrogram.
10
Pixton, Tonya S. "Expecting Happy Women, Not Detecting the Angry Ones : Detection and Perceived Intensity of Facial Anger, Happiness, and Emotionality." Doctoral thesis, Stockholms universitet, Psykologiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-57167.
Full textAbstract:
Faces provide cues for judgments regarding the emotional state of individuals. Using signal-detection methodology and a standardized stimulus set, the overall aim of the present dissertation was to investigate the detection of emotional facial expressions (i.e., angry and happy faces) with neutral expressions as the nontarget stimuli. Study I showed a happy-superiority effect and a bias towards reporting happiness in female faces. As work progressed, questions arose regarding whether the emotional stimuli were equal with regard to perceived strength of emotion, and whether the neutral faces were perceived as neutral. To further investigate the effect of stimulus quality on the obtained findings, Study II was designed such that the facial stimuli were rated on scales of happy-sad, angry-friendly, and emotionality. Results showed that ‘neutral’ facial expressions were not rated as neutral, and that there was a greater perceived distance between happy and neutral faces than between angry and neutral faces. These results were used to adjust the detectability measures to compensate for the varying distances of the angry and happy stimuli from the neutral stimuli in the emotional space. The happy-superiority effect was weakened, while an angry-female disadvantage remained. However, as these results were based upon different participant groups for detection and emotional rating, Study III was designed to investigate whether the results from Studies I and II could be replicated in a design where the same participants performed both tasks. Again, the results showed the non-neutrality of ‘neutral’ expressions and that happiness was more easily detected than anger, as shown in general emotion as well as specific emotion detection. Taken together, the overall results of the present dissertation demonstrate a happy-superiority effect that was greater for female than male faces, that angry-female faces were the most difficult to detect, and a bias to report female faces as happy.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: In press. Paper 2: Manuscript. Paper 3: Manuscript.
11
Abas, Ashardi B. "Non-intrusive driver drowsiness detection system." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5521.
Full textAbstract:
The development of technologies for preventing drowsiness at the wheel is a major challenge in the field of accident avoidance systems. Preventing drowsiness during driving requires a method for accurately detecting a decline in driver alertness and a method for alerting and refreshing the driver. As a detection method, the authors have developed a system that uses image processing technology to analyse images of the road lane with a video camera integrated with steering wheel angle data collection from a car simulation system. The main contribution of this study is a novel algorithm for drowsiness detection and tracking, which is based on the incorporation of information from a road vision system and vehicle performance parameters. Refinement of the algorithm is more precisely detected the level of drowsiness by the implementation of a support vector machine classification for robust and accurate drowsiness warning system. The Support Vector Machine (SVM) classification technique diminished drowsiness level by using non intrusive systems, using standard equipment sensors, aim to reduce these road accidents caused by drowsiness drivers. This detection system provides a non-contact technique for judging various levels of driver alertness and facilitates early detection of a decline in alertness during driving. The presented results are based on a selection of drowsiness database, which covers almost 60 hours of driving data collection measurements. All the parameters extracted from vehicle parameter data are collected in a driving simulator. With all the features from a real vehicle, a SVM drowsiness detection model is constructed. After several improvements, the classification results showed a very good indication of drowsiness by using those systems.
12
Mazel, Johan. "Unsupervised network anomaly detection." Thesis, Toulouse, INSA, 2011. http://www.theses.fr/2011ISAT0024/document.
Full textAbstract:
La détection d'anomalies est une tâche critique de l'administration des réseaux. L'apparition continue de nouvelles anomalies et la nature changeante du trafic réseau compliquent de fait la détection d'anomalies. Les méthodes existantes de détection d'anomalies s'appuient sur une connaissance préalable du trafic : soit via des signatures créées à partir d'anomalies connues, soit via un profil de normalité. Ces deux approches sont limitées : la première ne peut détecter les nouvelles anomalies et la seconde requiert une constante mise à jour de son profil de normalité. Ces deux aspects limitent de façon importante l'efficacité des méthodes de détection existantes.Nous présentons une approche non-supervisée qui permet de détecter et caractériser les anomalies réseaux de façon autonome. Notre approche utilise des techniques de partitionnement afin d'identifier les flux anormaux. Nous proposons également plusieurs techniques qui permettent de traiter les anomalies extraites pour faciliter la tâche des opérateurs. Nous évaluons les performances de notre système sur des traces de trafic réel issues de la base de trace MAWI. Les résultats obtenus mettent en évidence la possibilité de mettre en place des systèmes de détection d'anomalies autonomes et fonctionnant sans connaissance préalableAnomaly detection has become a vital component of any network in today’s Internet. Ranging from non-malicious unexpected events such as flash-crowds and failures, to network attacks such as denials-of-service and network scans, network traffic anomalies can have serious detrimental effects on the performance and integrity of the network. The continuous arising of new anomalies and attacks create a continuous challenge to cope with events that put the network integrity at risk. Moreover, the inner polymorphic nature of traffic caused, among other things, by a highly changing protocol landscape, complicates anomaly detection system's task. In fact, most network anomaly detection systems proposed so far employ knowledge-dependent techniques, using either misuse detection signature-based detection methods or anomaly detection relying on supervised-learning techniques. However, both approaches present major limitations: the former fails to detect and characterize unknown anomalies (letting the network unprotected for long periods) and the latter requires training over labeled normal traffic, which is a difficult and expensive stage that need to be updated on a regular basis to follow network traffic evolution. Such limitations impose a serious bottleneck to the previously presented problem.We introduce an unsupervised approach to detect and characterize network anomalies, without relying on signatures, statistical training, or labeled traffic, which represents a significant step towards the autonomy of networks. Unsupervised detection is accomplished by means of robust data-clustering techniques, combining Sub-Space clustering with Evidence Accumulation or Inter-Clustering Results Association, to blindly identify anomalies in traffic flows. Correlating the results of several unsupervised detections is also performed to improve detection robustness. The correlation results are further used along other anomaly characteristics to build an anomaly hierarchy in terms of dangerousness. Characterization is then achieved by building efficient filtering rules to describe a detected anomaly. The detection and characterization performances and sensitivities to parameters are evaluated over a substantial subset of the MAWI repository which contains real network traffic traces.Our work shows that unsupervised learning techniques allow anomaly detection systems to isolate anomalous traffic without any previous knowledge. We think that this contribution constitutes a great step towards autonomous network anomaly detection.This PhD thesis has been funded through the ECODE project by the European Commission under the Framework Programme 7. The goal of this project is to develop, implement, and validate experimentally a cognitive routing system that meet the challenges experienced by the Internet in terms of manageability and security, availability and accountability, as well as routing system scalability and quality. The concerned use case inside the ECODE project is network anomaly
13
Stadelman, Dennis LeRoy Weiner Donald D. "Coherent radar detection in non-Gaussian clutter." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.
Full text
14
Doyuran, Ulku. "Radar Target Detection In Non-gaussian Clutter." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608899/index.pdf.
Full textAbstract:
In this study, novel methods for high-resolution radar target detection in non-Gaussian clutter environment are proposed. In solution of the problem, two approaches are used: Non-coherent detection that operates on the envelope-detected signal for thresholding and coherent detection that performs clutter suppression, Doppler processing and thresholding at the same time. The proposed non-coherent detectors, which are designed to operate in non-Gaussian and range-heterogeneous clutter, yield higher performance than the conventional methods that were designed either for Gaussian clutter or heterogeneous clutter. The proposed coherent detector exploits the information in all the range cells and pulses and performs the clutter reduction and thresholding simultaneously. The design is performed for uncorrelated, partially correlated and fully correlated clutter among range cells. The performance analysis indicates the superiority of the designed methods over the classical ones, in fully correlated and partially correlated situations. In addition, by design of detectors for multiple targets and making corrections to the conventional methods, the target-masking problem of the classical detectors is alleviated.
15
Mayo, Elise. "A Non-filtering Gear Fault Detection Method." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34387.
Full textAbstract:
Rotating elements, including gears, are one of the most problematic elements in machinery. It is not preferable to monitor their condition visually considering time and money is required to take apart the machine to observe the parts. Monitoring of gears is important because the failure of such elements can cause major damage to machinery. A few non-invasive methods are proposed, however vibration analysis is, so far, the most efficient way to monitor the condition of the gear. Vibrations are caused by the continuous contact between the two rotating gears. When a fault occurs, the signal is modified in different ways depending on the type of fault - distributed or local. Many fault detection methods are effective for one type of fault or the other. In this thesis, several methods are proposed with the objective of finding an efficient method for both types of faults. The calculus enhanced energy operator (CEEO), previously designed for bearing fault detection, is proposed here for the first time on gears. Two other methods, the EO123 and EO23, are derived based on the original energy operator. The proposed methods are filter free, simple and can handle a certain level of noise and interference. With the exception of low rotational frequencies of the gears, it can be concluded from simulated and experimentally-obtained signals that the CEEO method can handle noise better than the other proposed methods and that the EO23 method can handle interference better than the others. Different conditions determine the effectiveness of the methods.
16
De, Felice Rachele. "Automatic error detection in non-native English." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:5192f0cb-6e4d-4730-bb54-a97a73d603ed.
Full textAbstract:
This thesis describes the development of Dapper (`Determiner And PrePosition Error Recogniser'), a system designed to automatically acquire models of occurrence for English prepositions and determiners to allow for the detection and correction of errors in their usage, especially in the writing of non-native speakers of the language. Prepositions and determiners are focused on because they are parts of speech whose usage is particularly challenging to acquire, both for students of the language and for natural language processing tools. The work presented in this thesis proposes to address this problem by developing a system which can acquire models of correct preposition and determiner occurrence, and can use this knowledge to identify divergences from these models as errors. The contexts of these parts of speech are represented by a sophisticated feature set, incorporating a variety of semantic and syntactic elements. DAPPER is found to perform well on preposition and determiner selection tasks in correct native English text. Results on each preposition and determiner are discussed in detail to understand the possible reasons for variations in performance, and whether these are due to problems with the structure of DAPPER or to deeper linguistic reasons. An in-depth analysis of all features used is also offered, quantifying the contribution of each feature individually. This can help establish if the decision to include complex semantic and syntactic features is justified in the context of this task. Finally, the performance of DAPPER on non-native English text is assessed. The system is found to be robust when applied to text which does not contain any preposition or determiner errors. On an error correction task, results are mixed: DAPPER shows promising results on preposition selection and determiner confusion (definite vs. indefinite) errors, but is less successful in detecting errors involving missing or extraneous determiners. Several characteristics of learner writing are described, to gain a clearer understanding of what problems arise when natural language processing tools are used with this kind of text. It is concluded that the construction of contextual models is a viable approach to the task of preposition and determiner selection, despite outstanding issues pertaining to the domain of non-native writing.
17
Schantz, Christopher James. "Non-intrusive fault detection in reciprocating compressors." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67800.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 128-130).
This thesis presents a set of techniques for non-intrusive sensing and fault detection in reciprocating compressors driven by induction motors. The procedures developed here are "non-intrusive" because they rely only on electrical measurements to reconstruct the mechanical signals internal to the compressor. This allows for easy and non-intrusive determination of many fault sensitive signals that usually require complicated, expensive, and time consuming operations to measure. A sample of the signals produced by the procedures of this thesis are estimates of the cylinder suction and discharge pressures and a composite torque signal containing the effects of the mechanical loads within the compressor. This load torque signal is especially sensitive to faults, and a demonstration of the effect on and detection of compressor valve faults from the load torque signal is given. One of the key steps in the algorithm presented here is a procedure to "invert" the induction motor dynamic model equations to allow direct calculation of motor shaft speed and torque from stator current and voltage measurements. For this procedure a non-intrusive method to estimate motor model parameters from an in-situ induction motor driving a periodic load was developed.
by Christopher James Schantz.
S.M.
18
Kolluri, Murali Mohan. "Non-parametric nonlinearity detection under broadband excitation." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1573224392534571.
Full text
19
Giovanny, Giron Amaya Edwin. "Non-parametric edge detection in speckled imagery." Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/6193.
Full textAbstract:
Made available in DSpace on 2014-06-12T18:02:43Z (GMT). No. of bitstreams: 2
arquivo4052_1.pdf: 1926198 bytes, checksum: a394edbf4f303fa7b25af920df83cf25 (MD5)
license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5)
Previous issue date: 2008Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Este trabalho propõe uma técnica não-paramétrica para detecção de bordas em imagens speckle. As imagens SAR ("Synthetic aperture Radar"), sonar, B-ultrasound e laser são corrompidas por um ruído não aditivo chamado speckle. Vários modelos estatísticos foram propostos para desrever este ruído, levando ao desenvolvimento de técnicas especiais para melhoramento e análise de imagens. A distribuição G0 é um modelo estatístico que consegue descrever uma ampla gama de áreas, como, por exemplo, em dados SAR, pastos (lisos), florestas (rugosos) e áreas urbanas (muito rugosos). O objetivo deste trabalho é estudar ténicas alternativas na detecção de imagens speckled, tomando como ponto de partida Gambini et al. (2006, 2008). Um novo detector de borda baseado no teste de Kruskal Wallis é proposto. Os nossos resultados numéricos mostram que esse detector é uma alternativa atraente ao detector de M. Gambini, que é baseado na função de verossimilhançaa. Neste trabalho fornecemos evidências de que a técnica de M. Gambini pode ser substituída om sucesso pelo método Kruskal Wallis. O ganho reside em ter um algoritmo 1000 vezes mais rápido, sem omprometer a qualidade dos resultados
20
Diczfalusy, Elin, and Sarah Broberg. "Non-Invasive Methods for Detecting Drug and Alcohol Impaired Drivers : - a Study of Alcohol and Drug Biomarkers and Optical Detection Techniques." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-16645.
Full textAbstract:
In recent years, the use of alcohol and psychoactive drugs in combination withdriving has recieved increased attention. The lack of in-vehicle devices capable ofdetecting recent drug consumption and the difficulties associated with the breathbasedalcolocks in use today makes it interesting to investigate methods that areable to non-invasivelly measure analytes directly in the blood.
The assignment of this project, commissioned by Volvo Technology Corporationand Volvo Car Corporation, is to map substances that constitute a possible threatto traffic safety, identify suitable detection markers as a proof of administrationof these substances, and study possible non-invasive techniques to detect thesemarkers. The objective is to present for Volvo if and how to continue evaluatingand developing a non-invasive detection device.
The project has been carried out by performing an extensive literature study and averification experiment. From the literature review, a number of substances affectingdriving performance could be identified, and a metabolic study was performedfor each drug to map suitable biomarkers. Furthermore, two potential techniquesfor non-invasive detection, near-infrared Raman spectroscopy and near-infraredspectroscopy, were found and evaluated. The experiment was conducted usingnear-infrared Raman spectroscopy, with the aim of investigating the sensitivityand linearity of the method for ethanol detection.
Based on the theoretical evaluation, both near-infrared Raman spectroscopy andnear-infrared spectroscopy are expected to have potential for non-invasive detectionof ethanol. The experiment further proved the theoretical conclusionsmade for near-infrared Raman spectroscopy. However, neither of the techniquesis thought to have potential for drug detection.Altogether, we believe that non-invasive ethanol detection is possible, but suggestfurther experiments in order to determine which technique to be preferred.
21
Chuah, Teong Chee. "Robust techniques for multiuser CDMA communications in non Gaussian noise environments." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246626.
Full text
22
Christoffersson, Anton. "Standalone vehicle emergency detection." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63956.
Full textAbstract:
When testing cars on proving grounds, a solution to monitor and track the vehicle is often needed. Rajd Systech’s solution, Nelson, uses a mobile device mounted in the car to monitor the vehicle and generate events based on information from it. One of the most important events generated are the accident events which notifies the facility manager that something has happened. This thesis will describe how a standalone collision detection library is created to improve upon the existing applications events, giving it the feature to detect when an emergency happens on the track with the help of the mobile phones internal sensorsNär man testar bilar på testanläggningar behövs det en lösning för att övervaka och spåra bilarna. Rajd Systrech’s lösning, Nelson, använder en mobilenhet som är monterad i bilen för att övervaka fordonet och genererar event utifrån information som den samlar. Ett av det viktigaste av dom generade eventen är olyckshändelse eventet som notifierar personen som övervakar testanläggningen att någonting har hänt. Det här examensarbetet beskriver hur ett fristående kollisionsdetekteringsbibliotek skapats för att förbättra de befintliga applikations eventet, vilket ger applikationen funktionen att upptäcka när en nödsituation hänt på banan med hjälp av mobilens interna sensorer.
23
Park, Hyung Chul, Kwyro Lee, and Kamilo Feher. "NON-COHERENTLY DETECTED FQPSK: RAPID SYNCHRONIZATION AND COMPATIBILITY WITH PCM/FM RECEIVERS." International Foundation for Telemetering, 2001. http://hdl.handle.net/10150/606461.
Full textAbstract:
International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, NevadaA new class of non-coherent detection techniques for recently standardized Feher patented quadrature phase-shift keying (FQPSK) systems is proposed and studied by computer aided design/simulations and also verified by experimental hardware measurements. The theoretical concepts of the described non-coherent techniques are based on an interpretation of the instantaneous frequency deviation or phase transition characteristics of FQPSK-B modulated signal at the front end of the receiver. These are accomplished either by Limiter-Discriminator (LD) or by Limiter-Discriminator followed by Integrate-and-Dump (LD I&D) methods. It is shown that significant BER performance improvements can be obtained by increasing the received signal’s observation time over multiple symbols as well as by adopting trellis-demodulation. For example, our simulation results show that a BER=10^-4 can be obtained for an E(b)/N(0)=12.7 dB.
24
Watson, Joseph Conrad. "Eddy current detection of magnetic and non-magnetic metallic edges beneath continuous plate." Thesis, Brunel University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394797.
Full text
25
Lu, Sixing, and Sixing Lu. "Non-intrusive Runtime Anomaly Detection for Embedded Systems." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626111.
Full textAbstract:
Malware is a serious threat to network-connected embedded systems, as evidenced by the continued and rapid growth of such devices, commonly referred to as of the Internet of Things. Their ubiquitous use in critical applications require robust protection to ensure user safety and privacy. That protection must be applied to all system aspects, extending beyond protecting the network and external interfaces. Anomaly detection is one of the last lines of defense against malware, it can detect malware in embedded systems effectively and provide the advantage of detecting zero-day exploits relative to signature-based detection methods. However, embedded systems, particularly edge devices, face several challenges in applying data-driven anomaly detection, including unpredictability of malware, limited tolerance to long data collection windows, and limited computing/energy resources.
In this dissertation, we present a formal runtime security model that defines the normal system behavior including execution sequence and execution timing. We utilize both lumped timing and subcomponent timing information of software execution, the latter of which includes intrinsic software execution, instruction cache misses, and data cache misses, to detect the anomalies based on ranges, multi-dimensional Euclidean distance, and classification at runtime. We design several on-chip hardware detectors implementing these data-driven detection methods, which non-intrusively measure lumped/subcomponent timing of all system/function calls of the embedded application through trace port of the processor and detect malicious activity at runtime. We evaluate the detection accuracy, false positives, area overhead, power consumption, and detection latency of the presented detector designs with two network-connected embedded system prototypes and several mimicry attacks. We further analyze the properties of the timing distribution for control flow events, and select subset of monitoring targets by three selection metrics to meet hardware constraint. Experimental results demonstrate that the subcomponent timing model provides sufficient features to achieve high detection accuracy with low false positive rates using a one-class support vector machine, considering sophisticated mimicry malware.
26
Stensson, Katarina. "Generation and detection of non-classical photon states." Licentiate thesis, KTH, Tillämpad fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-228058.
Full textAbstract:
This thesis intends to familiarize the reader with the concepts of photon statistics and correlations in quantum optics. Developing light sources that emit quantum states is central for the realization of quantum technologies. One important step in characterizing these sources is the measurement of field fluctuations and correlations, by coincidence measurements. The expectation value of a coincidence measurement, a simultaneous measurement of two intensities (or, more general, four fields), is represented by the fourth-order correlation function. The value of the correlation function, at zero delay between the detection of two photons, reveals important properties of the state to which they belonged, for example the fluctuations of the photon number. Since predictability is important for many applications, light sources emitting single photons are also characterized by the indistinguishability of consecutively emitted photons, or of two photons from separate emitters. In paper I we investigate blinking behaviour in quantum emitters, and its effect on the interference pattern and photon statistics with photons from two separate emitters. Blinking refers to an emitters transition into a non-emitting state, and subsequent transition back to an emitting state. We show that blinking can not be treated as linear loss, when measuring the fourth-order correlation function for two emitters in a Hong-Ou-Mandel setup. In general, a measurement of the fourth-order correlation function is robust to loss, which makes it a very practical tool. However, the relation between recorded coincidence counts and the correlation function is only direct in the limit of zero detection efficiency, and depends on the detection system. In paper II, we show that by adding a variable attenuation in the beam path, we can trace back to the ''true'' value of the correlation function at zero quantum efficiency. This method improves accuracy in correlation measurements by decreasing a systematic error at the expense of an increased statistical error, which is easier to handle, extending the use of coincidence methods to classical and non-classical multi-photon states.QC 20180517
27
Peng, Wei. "Non-linear detection algorithms for MIMO multiplexing systems." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39558563.
Full text
28
Vasdekis, Spyridon. "Non invasive detection and quantification of venous reflux." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281766.
Full text
29
Cumberbatch, Daniel T. "The indirect detection of non-Baryonic Dark Matter." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489426.
Full textAbstract:
The understanding of the nature of the dominant forms of matter and energy in the Universe is undoubtedly one of the most intriguing concepts within the vast domain of current scientific research. Current experimental evidence supports the notion that the dominant form of matter in the Universe is composed of a non-luminous, possibly exotic, material that is distinct from the familiar baryonic matter from which the luminous Universe is composed.
30
Huang, Y. H. "Computational detection of non-coding RNAs in genomes." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604701.
Full textAbstract:
This thesis is devoted to assessing available approaches and trying new solutions for finding ncRNAs in genomes. In the first half of this thesis, reasons that may contribute to the slow progress of genome-wide ncRNA finding are explored. A comprehensive analysis on a genome-wide scale of the credibility of currently used signals for classifying ncRNAs is conducted. Two factors, conservation of ncRNAs in human-mouse synthetic regions and abundance of covariations between human-mouse synteny-conserved ncRNAs, are evaluated. The result reveals that current comparative-genomics-based methods may not be able to find ncRNAs effectively in mammalian genomes. In addition, possible genomic features that could distinguish real ncRNAs from pseudogenes are investigated. Two different criteria, distribution of bit scores and physical clustering in genomes, are applied to filter out tRNA pseudogenes and to enrich bona-fide tRNA genes. Physiological roles of the tRNA genes in human-mouse synteny-conserved clusters are discussed and the degradation patterns of tRNA pseudogenes are analyzed. In the second half of this thesis, computational techniques are applied to model signals that may be potentially useful for genome-wide ncRNA finding. A sparse Bayesian learning algorithm, Eponine, is applied to model the transcription start sites of mammalian ncRNA genes that are transcribed by RNA polymerase III. In addition to modelling cis-regulatory elements for transcription, a new computational module, which extends the capability of Eponine to learn motifs consisting of both primary sequences and RNA secondary structures, is created. The capability of this new module is demonstrated by applying it to analyze several known cases of ncRNA motifs. The strength and the weakness of applying this new computational approach for finding ncRNAs are discussed.
31
Peng, Wei, and 彭薇. "Non-linear detection algorithms for MIMO multiplexing systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39558563.
Full text
32
Amraoui, Mohamed Yacine. "Non-invasive damage detection and structural health monitoring." Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271865.
Full text
33
O'Reilly, Colin. "Anomaly detection in non-stationary and distributed environments." Thesis, University of Surrey, 2014. http://epubs.surrey.ac.uk/809414/.
Full textAbstract:
Anomaly detection is an important aspect of data analysis in order to identify data items that significantly differ from normal data. It is used in a variety of fields such as machine monitoring, environmental monitoring and security applications and is a well-studied area in the field of pattern recognition and machine learning. In this thesis, the key challenges of performing anomaly detection in non-stationary and distributed environments are addressed separately. In non-stationary environments the data distribution may alter, meaning that the concepts to be learned evolve in time. Anomaly detection techniques must be able to adapt to a non-stationary data distribution in order to perform optimally. This requires an update to the model that is being used to classify data. A batch approach to the problem requires a reconstruction of the model each time an update is required. Incremental learning overcomes this issue by using the previous model as the basis for an update. Two kernel-based incremental anomaly detection techniques are proposed. One technique uses kernel principal component analysis to perform anomaly detection. The kernel eigenspace is incrementally updated by splitting and merging kernel eigenspaces. The technique is shown to be more accurate than current state-of-the-art solutions. The second technique offers a reduction in the number of computations by using an incrementally updated hypersphere in kernel space. In addition to updating a model, in a non-stationary environment an update to the parameters of the model are required. Anomaly detection algorithms require the selection of appropriate parameters in order to perform optimally for a given data set. If the distribution of the data changes, an update to the parameters of a model is required. An automatic parameter optimization procedure is proposed for the one-class quartersphere support vector machine where the v parameter is selected automatically based on the anomaly rate in the training set. In environments such as wireless sensor networks, data might be distributed amongst a number of nodes. In this case, distributed learning is required where nodes construct a classifier, or an approximation of the classifier, that would have been formed had all the data been available to one instance of the algorithm. A principal component analysis based anomaly detection method is proposed that uses the solution to a convex optimization problem. The convex optimization problem is then derived in a distributed form, with each node running a local instance of the algorithm. Nodes are able to iterate towards an anomaly detector equivalent to the global solution by exchanging short messages. Detailed evaluations of the proposed techniques are performed against existing state-of-the-art techniques using a variety of synthetic and real-world data sets. Results in the area of a non-stationary environment illustrate the necessity to adapt an anomaly detection model to the changing data distribution. It is shown that the proposed incremental techniques are maintain accuracy while reducing the number of computations. In addition, optimal parameters derived from an unlabelled training set are shown to exhibit superior performance to statically selected parameters. In the area of a distributed environment, it is shown that local learning is insufficient due to the lack of examples. Distributed learning can be performed in a manner where a centralized model can be derived by passing small amounts of information between neighbouring nodes. This approach yields a model that obtains performance equal to that of the centralized model.
34
Cohen, Eric D. M. Eng Massachusetts Institute of Technology. "Vibration detection in turbomachinery using non-contacting sensors." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38330.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 103-105).
Recent developments have seen the introduction of multiple Eddy Current Sensors (ECS) into turbomachinery. These sensors employ an active magnetic field to monitor each blade as it passes the sensor. They generate an electrical signal proportional to the distance of a blade from the sensor. Existing algorithms extract two pieces of information from the ECS signature, signal magnitude and signal zero crossing time. The signal magnitude is used to find tip clearance, and the zero crossing time is used to estimate vibrational parameters over the course of multiple revolutions. These techniques fail to exploit the majority of the information contained in the ECS signal. In this research, a novel residue characterization algorithm was developed that processes the full ECS pulse to produce a residue. The residue is a speed independent representation of differences between a baseline ECS pulse and an experimental ECS pulse. A mathematical model of the relationship between blade displacement and residue was developed. Empirical data collected with the MIT spin pit were used to verify convergence of the model with the residue characterization algorithm. This strongly suggests blade vibration can be deduced using the residue characterization method with a single ECS sensor.
by Eric D. Cohen.
M.Eng.
35
Almin, Fredrik. "Detection of Non-Ferrous Materials with Computer Vision." Thesis, Linköpings universitet, Datorseende, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-175519.
Full textAbstract:
In one of the facilities at the Stena Recycling plant in Halmstad, Sweden, about 300 tonnes of metallic waste is processed each day with the aim of sorting out all non-ferrous material. At the end of this process, non-ferrous materials are manually sorted out from the ferrous materials. This thesis investigates a computer vision based approach to identify and localize the non-ferrous materials and eventually automate the sorting.Images were captured of ferrous and non-ferrous materials. The images areprocessed and segmented to be used as annotation data for a deep convolutionalneural segmentation network. Network models have been trained on different kinds and amounts of data. The resulting models are evaluated and tested in ac-cordance with different evaluation metrics. Methods of creating advanced train-ing data by merging imaging information were tested. Experiments with using classifier prediction confidence to identify objects of unknown classes were per-formed. This thesis shows that it is possible to discern ferrous from non-ferrous mate-rial with a purely vision based system. The thesis also shows that it is possible to automatically create annotated training data. It becomes evident that it is possi-ble to create better training data, tailored for the task at hand, by merging image data. A segmentation network trained on more than two classes yields lowerprediction confidence for objects unknown to the classifier.Substituting manual sorting with a purely vision based system seems like aviable approach. Before a substitution is considered, the automatic system needsto be evaluated in comparison to the manual sorting.
36
Pessaux, François. "Detection statique d'exceptions non rattrapees en objective caml." Paris 6, 1999. http://www.theses.fr/1999PA066398.
Full textAbstract:
De nombreux langages de programmation fournissent un support natif pour les exceptions : lever une exception a un endroit du programme transfere le controle au gestionnaire pour cette exception le plus proche dans la pile des appels dynamiques du programme. Les exceptions fournissent donc un moyen simple et flexible de gestion des erreurs dans les applications. Neanmoins, en l'absence de gestionnaire pour une exception levee, celle-ci mettra fin prematurement a l'execution du programme. Ce style de terminaison sur erreur affaiblit donc la robustesse et la fiabilite des programmes. Le but de cette these est donc de realiser un outil d'analyse permettant de predire les exceptions pouvant mettre terme a l'execution des programmes. Ce travail etudie donc la theorie et l'implementation d'un tel analyseur base sur un systeme de types et d'effets utilisant un mecanisme de rangees afin d'approximer a la fois le flot des exceptions non rattrapees et le flot des valeurs. Il expose le cadre theorique de l'analyse, etablit formellement ses proprietes et montre sa capacite a etre etendu a un langage de taille reelle comme objective caml. Par ailleurs cette these decrit un nouvel algorithme d'inference de types en presence de recursion polymorphe pour ml. En effet, il apparait que cette technique peut servir a rendre plus precis les resultats de notre analyse. Cet algorithme presente les interets d'etre formalise dans le cadre d'un typeur avec niveaux (c'est-a-dire suivant le principe reel d'un typeur ml efficace), d'etre rapide et de rejeter extremement peu de programmes (car ce type d'inference etant connue pour etre indecidable seule une restriction des programmes acceptes peut mener a un algorithme). Ce travail aboutit a l'implantation effective d'un analyseur d'exceptions pour et en objective caml, accompagne d'une interface utilisateur rendant l'acces aux resultats de l'analyse plus aisee.
37
Reid, Katherine Gregor. "Characterisation and non-cultural detection of Neisseria gonorrhoeae." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/20141.
Full text
38
Tsang, Wai-ming Peter. "Computer aided ultrasonic flaw detection and characterization /." [Hong Kong : University of Hong Kong], 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12344928.
Full text
39
Bourin, Stephanie. "Novel strategies for DNA detection assay." Thesis, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265939.
Full text
40
Faghidi, Hamid. "Non-parametric and Non-filtering Methods for Rolling Element Bearing Condition Monitoring." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30689.
Full textAbstract:
Rolling element bearings are one of the most significant elements and frequently-used components in mechanical systems. Bearing fault detection and diagnosis is important for preventing productivity loss and averting catastrophic failures of mechanical systems. In industrial applications, bearing life is often difficult to predict due to different application conditions, load and speed variations, as well as maintenance practices. Therefore, reliable fault detection is necessary to ensure productive and safe operations.
Vibration analysis is the most widely used method for detection and diagnosis of bearing malfunctions. A measured vibration signal from a sensor is often contaminated by noise and vibration interference components. Over the years, many methods have been developed to reveal fault signatures, and remove noise and vibration interference components.
Though many vibration based methods have been proposed in the literature, the high frequency resonance (HFR) technique is one of a very few methods have received certain industrial acceptance. However, the effectiveness of the HFR methods depends, to a great extent, on some parameters such as bandwidth and centre frequency of the fault excited resonance, and window length. Proper selection these parameters is often a knowledge-demanding and time-consuming process. In particular, the filter designed based on the improperly selected bandwidth and center frequency of the fault excited resonance can filter out the true fault information and mislead the detection/diagnosis decisions. In addition, even if these parameters can be selected properly at beginning of each process, they may become invalid in a time-varying environment after a certain period of time. Hence, they may have to be re-calculated and updated, which is again a time-consuming and error-prone process. This undermines the practical significance of the above methods for online monitoring of bearing conditions.
To overcome the shortcomings of existing methods, the following four non-parametric and non-filtering methods are proposed:
1. An amplitude demodulation differentiation (ADD) method,
2. A calculus enhanced energy operator (CEEO) method,
3. A higher order analytic energy operator (HO_AEO) approach, and
4. A higher order energy operator fusion (HOEO_F) technique.
The proposed methods have been evaluated using both simulated and experimental data.
41
Al-Nashash, H. A. M. "Non-invasive beat-to-beat detection of His-Purkinje system electrograms." Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381002.
Full text
42
Mezil, Sylvain. "Nonlinear optoacoustics method for crack detection and characterization." Phd thesis, Université du Maine, 2012. http://tel.archives-ouvertes.fr/tel-01037936.
Full textAbstract:
This thesis deals with crack detection by a nonlinear optoacoustic method. The samples are glass plates containing a centimeter length and micrometer thick crack. The developed method is based on the absorption of two light beams, independently modulated, and focused at the same location on the sample. This causes the generation of two waves, by thermal expansion. The first one is a thermoelastic wave at low frequency fL (~Hz), and the second is an acoustical one at high frequency fH (tens of kHz). When a crack is present in the heated zone, the thermoelastic wave can make it breathe. The crack is expected to close (open) when the intensity of the heating laser modulated at fL is high (low). This breathing influences the acoustic wave generated in the vicinity of the crack at fH. It results a nonlinear frequency-mixing process, leading to the generation of new frequencies: fH±n fL (n=1,2,...). The detection of these mixed-frequencies indicates the presence of a crack.
43
Frontera, Pons Joana Maria. "Robust target detection for Hyperspectral Imaging." Thesis, Supélec, 2014. http://www.theses.fr/2014SUPL0024/document.
Full textAbstract:
L'imagerie hyperspectrale (HSI) repose sur le fait que, pour un matériau donné, la quantité de rayonnement émis varie avec la longueur d'onde. Les capteurs HSI mesurent donc le rayonnement des matériaux au sein de chaque pixel pour un très grand nombre de bandes spectrales contiguës et fournissent des images contenant des informations à la fois spatiale et spectrale. Les méthodes classiques de détection adaptative supposent généralement que le fond est gaussien à vecteur moyenne nul ou connu. Cependant, quand le vecteur moyen est inconnu, comme c'est le cas pour l'image hyperspectrale, il doit être inclus dans le processus de détection. Nous proposons dans ce travail d'étendre les méthodes classiques de détection pour lesquelles la matrice de covariance et le vecteur de moyenne sont tous deux inconnus.Cependant, la distribution statistique multivariée des pixels de l'environnement peut s'éloigner de l'hypothèse gaussienne classiquement utilisée. La classe des distributions elliptiques a été déjà popularisée pour la caractérisation de fond pour l’HSI. Bien que ces modèles non gaussiens aient déjà été exploités dans la modélisation du fond et dans la conception de détecteurs, l'estimation des paramètres (matrice de covariance, vecteur moyenne) est encore généralement effectuée en utilisant des estimateurs conventionnels gaussiens. Dans ce contexte, nous analysons de méthodes d’estimation robuste plus appropriées à ces distributions non-gaussiennes : les M-estimateurs. Ces méthodes de détection couplées à ces nouveaux estimateurs permettent d'une part, d'améliorer les performances de détection dans un environment non-gaussien mais d'autre part de garder les mêmes performances que celles des détecteurs conventionnels dans un environnement gaussien. Elles fournissent ainsi un cadre unifié pour la détection de cibles et la détection d'anomalies pour la HSIHyperspectral imaging (HSI) extends from the fact that for any given material, the amount of emitted radiation varies with wavelength. HSI sensors measure the radiance of the materials within each pixel area at a very large number of contiguous spectral bands and provide image data containing both spatial and spectral information. Classical adaptive detection schemes assume that the background is zero-mean Gaussian or with known mean vector that can be exploited. However, when the mean vector is unknown, as it is the case for hyperspectral imaging, it has to be included in the detection process. We propose in this work an extension of classical detection methods when both covariance matrix and mean vector are unknown.However, the actual multivariate distribution of the background pixels may differ from the generally used Gaussian hypothesis. The class of elliptical distributions has already been popularized for background characterization in HSI. Although these non-Gaussian models have been exploited for background modeling and detection schemes, the parameters estimation (covariance matrix, mean vector) is usually performed using classical Gaussian-based estimators. We analyze here some robust estimation procedures (M-estimators of location and scale) more suitable when non-Gaussian distributions are assumed. Jointly used with M-estimators, these new detectors allow to enhance the target detection performance in non-Gaussian environment while keeping the same performance than the classical detectors in Gaussian environment. Therefore, they provide a unified framework for target detection and anomaly detection in HSI
44
Rayner, Stephen Mark. "Very high energy gamma rays from isolated pulsars and non-pulsating objects." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6458/.
Full textAbstract:
This thesis is concerned with the detection of very high energy 7-rays from isolated pulsars and objects that are not known to emit pulsed radiation, using the atmospheric Cerenkov technique. The first chapter summarises the processes by which celestial 7-rays can be generated and absorbed. A discussion of the criteria for selecting objects for study is given. The second chapter describes the atmospheric Cerenkov technique and gives a brief outline of its historical development. Details of the design and operation of the current Durham university V.H.E. 7- ray telescopes are given. The third chapter describes the standard analysis techniques used to search for pulsed and unpulsed emission. The fourth chapter presents results of new observations of four isolated pulsars. Upper limits to the V.H.E. 7-ray flux are derived for each pulsar. A summary of the results is given and conclusions drawn regarding the consequences of the observations for the most popular pulsar model. The fifth chapter deals with new analysis techniques that have been developed to test data for the presence of a signal which is not necessarily periodic. A number of different approaches is described. The results of these techniques when applied to simulated data are presented and conclusions are drawn regarding the relative effectiveness of the tests. The sixth chapter applies the most successful test to data from three objects. Upper limits to the flux from Centaurus A and SN1987aare derived from our observations. Evidence for V.H.E. 7-ray emission from Scorpius X-1 is presented, together with evidence that this emission is modulated with the period of the binary orbit of this system. The final chapter summarises the preceding results and conclusions and indicates areas where current research may lead to substantial improvements in telescope design and analysis techniques.
45
Dosso, Mamadou. "Discrimination ultrasonore des défauts par traitement numérique de leurs échos." Châtenay-Malabry, Ecole centrale de Paris, 1986. http://www.theses.fr/1986ECAP0003.
Full text
46
Hamzah, Ab Razak. "The application of transient thermography to defect detection." Thesis, University of Bath, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296326.
Full text
47
Mejia, Paloma Yasmin. "Smart Systems for Damage Detection and Prognosis." Miami University Honors Theses / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1114101552.
Full text
48
Azary, Sherif. "Detection of deformable objects in a non-stationary scene /." Link to online version, 2005. https://ritdml.rit.edu/dspace/handle/1850/1178.
Full text
49
Kuyucak, Selçuk. "Direct detection of non-metallic inclusions in molten iron." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63356.
Full text
50
Acton, Matthew Nicholas Frederick. "Response Prediction and Detection in Non-linear Clamped Panels." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504772.
Full textAbstract:
Aircraft panels may often be subjected to high levels ofacoustic pressure loading in flight that may lead to fatigue damage. In some cases, the in-plane restraint provided by the panel boundaries will introduce a geometric stiffening non-linearity when the panel deforms. This Thesis is split into two main areas in the field of non-linear dynamics. Firstly the prediction ofthe non-linear response ofa structure to acoustic excitation for use in sonic fatigue life calculations is examined. The second area of consideration is the detection ofthe presence of non-linearities in a structure when there may more than one present. The Non-Linear Modal method (NLMOD) previously developed at the University of Manchester, allows the prediction ofthe kinematic and stress response of such panels via a reduced order approach that converts Finite Element results into a model based in linear modal space, with additional terms included to represent the non-linear behavior. In this Thesis, the development ofan experimental clamped panel structure is presented, together with several Finite Element models ofthe same structure. The panel is tested for its modal and static characteristics and exposed to fairly high-level acoustic excitation in a Progressive Wave Tube (PWT). The resulting non-linear strain responses are compared to those predicted using the identified non-linear modal model. Discrepancies are initially found between test and prediction. Reasons for the discrepancies are discussed and the model modified accordingly. Good final agreement with test results is found and a number of areas for further investigation are highlighted. The second part of the Thesis develops a novel, simple method for detecting the presence of non-linear stiffness and non-linear damping, when both may be present, using higher order statistics ofthe time domain response ofa structure. The method is developed using simulation of a single degree offreedom system and is then validated using a clamped panel. In order to ensure the presence of non-linear damping, a novel discrete, non-linear damper is developed making use of a passive shaker with the terminals shorted.