To see the other types of publications on this topic, follow the link: Rain detection.

Dissertations / Theses on the topic 'Rain detection'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 dissertations / theses for your research on the topic 'Rain 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

Webster, Dereck D. "Automatic Rain Drop Detection for Improved Sensing in Automotive Computer Vision Applications." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9154.

Full text
Abstract:
The presence of raindrop induced distortion can have a significant negative impact on computer vision applications. Here we address the problem of visual raindrop distortion in standard colour video imagery for use in non-static, automotive computer vision applications where the scene can be observed to be changing over subsequent consecutive frames. We utilise current state of the art research conducted into the investigation of salience mapping as means of initial detection of potential raindrop candidates. We further expand on this prior state of the art work to construct a combined feature rich descriptor of shape information (Hu moments), isolation of raindrops pixel information from context, and texture (saliency derived) within an improved visual bag of words verification framework. Support Vector Machine and Random Forest classification were utilised for verification of potential candidates, and the effects of increasing discrete cluster centre counts on detection rates were studied. This novel approach of utilising extended shape information, isolation of context, and texture, along with increasing cluster counts, achieves a notable 13% increase in precision (92%) and 10% increase in recall (86%) against prior state of the art. False positive rates were also observed to decrease with a minimal false positive rate of 14% observed.
APA, Harvard, Vancouver, ISO, and other styles
2

Köylüoglu, Tugay, and Lukas Hennicks. "Evaluating rain removal image processing solutions for fast and accurate object detection." Thesis, KTH, Mekatronik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254446.

Full text
Abstract:
Autonomous vehicles are an important topic in modern day research, both for the private and public sector. One of the reasons why self-driving cars have not yet reached consumer market is because of levels of uncertainty. This is often tackled with multiple sensors of different kinds which helps gaining robust- ness in the vehicle’s system. Radars, lidars and cameras are often the sensors used and the expenses can rise up quickly, which is not always feasible for different markets. This could be addressed with using fewer, but more robust sensors for visualization. This thesis addresses the issue of one particular failure mode for camera sensors, which is reduced view range affected by rainy weather. Kalman filter and discrete wavelet transform with bilateral filtering are evaluated as rain removal algorithms and tested with the state-of-the-art object detection algorithm, You Only Look Once (YOLOv3). Filtered videos in daylight and evening light were tested with YOLOv3 and results show that the accuracy is not improved enough to be worth implementing in autonomous vehicles. With the graphics card available for this thesis YOLOv3 is not fast enough for a vehicle to stop in time when driving in 110km/h and an obstacle appears 80m ahead, however an Nvidia Titan X is assumed to be fast enough. There is potential within the research area and this thesis suggests that other object detection methods are evaluated as future work.
Autonoma fordon är för privat samt offentlig sektor ett viktigt område i modern forskning. Osäkerheten med autonoma fordon är en viktig anledning till varför de idag inte nått konsumentmarknaden. Systemen för autonoma fordon blir mer robusta med inkludering av flera sensorer av olika typer, vilka oftast är kameror, radar och lidars. Fordon med dessa sensorer kan snabbt öka i pris vilket gör dem mindre tillgängliga för olika marknader. Detta skulle kunna lösas med färre sensorer som däremot är mer robusta. Denna avhandling diskuterar problemet med en specific felmodell för kameror, vilket är minskat synfält som påverkas av regnigt väder. Kalman filter och diskret vågkomponent-transformation med bilateral filtrering utvärderades som regnborttagningsalgoritmer och testades med You Only Look Once (YOLOv3), en modern objektigenkänningsmetod. Filtrerade videofilmer i dagstid och kvällstid testades med YOLOv3 och resultaten visade att noggrannheten inte ökade tillräckligt mycket för att vara användbara för autonoma fordon. Med grafikkorten tillgängliga för denna avhandling är inte YOLOv3 snabb nog för ett fordon att hinna stanna i tid före kollision om bilen kör i 110km/h och ett föremål dyker upp 80m framför. Däremot antas det att fordon utrustade med Nvidias Titan X borde hinna stanna i tid före kollision. Avhandlingen ser däremot potential inom detta forskningsområde och föreslår att liknande test fast med andra objektigenkänningsmetoder bör utföras.
APA, Harvard, Vancouver, ISO, and other styles
3

Ferroudj, Meriem. "Detection of rain in acoustic recordings of the environment using machine learning techniques." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82848/1/Meriem_Ferroudj_Thesis.pdf.

Full text
Abstract:
This thesis is concerned with the detection and prediction of rain in environmental recordings using different machine learning algorithms. The results obtained in this research will help ecologists to efficiently analyse environmental data and monitor biodiversity.
APA, Harvard, Vancouver, ISO, and other styles
4

Ma, Bin-Bing. "Passive acoustic detection and measurement of rainfall at sea and an empirical ocean ambient sound model /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/11045.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Allen, Jeffrey R. "An Analysis of SeaWinds Simultaneous Wind/Rain Retrieval in Severe Weather Events." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd704.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Marinaro, Ralph Michael. "Investigation of water vapor effects on the detection of nitric acid vapor with the tungstic acid technique." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/71262.

Full text
Abstract:
An automated tungstic acid technique (TAT) has been successfully used to measure gaseous HNO₃ in the presence of water vapor. The TAT is based on the diffusion of gaseous HNO₃ to the interior walls of a tube coated with tungsten VI oxide (WO₃), where it is selectively chemisorbed. The collected HNO₃ sample is thermally desorbed from the WO₃ surface, as NO, and measured by a chemiluminescent oxides of nitrogen analyzer. The integrated analyzer response is directly proportional to the nitric acid collected. Based on nitric acid hydration characteristics, a decrease in the diffusion coefficient and thus collection efficiency for denuder type measurement techniques may result with increased atmospheric water vapor (i.e., relative humidity). This study emphasizes the effect of water vapor (i.e., relative humidity) as a potential interferent for HNO₃ collection with the TAT system. The effect of water vapor (< 78% RH) on the collection efficiency for HNO₃ with the tungstic acid technique is negligible at 25°C, but is significant only at elevated sampling temperatures. This threshold effect is further substantiated and eliminated when a modified sampling collection system was designed with coolant capabilities. The new design has been tested to sub-part-per-billion (NOx analyzer detection limit) levels with minimal loss of gaseous HNO₃ signal, thereby increasing sensitivity to atmospheric HNO₃ concentrations and maintaining the gas/aerosol sample integrity.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
7

Liu, Zhongxun. "Modélisation des signatures radar des tourbillons de sillage par temps de pluie." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0015/document.

Full text
Abstract:
La surveillance des turbulences de sillage par radar en temps de pluie présente un intérêt à la fois pratique et scientifique. Cette thématique a été traitée à travers trois étapes successives.Tout d’abord, le mouvement et la distribution des gouttes d’eau dans les vortex ont été modélisés et simulés. A partir de l’équation de la dynamique appliquée sur une goutte d’eau, une méthode de calcul de la trajectoire des gouttes d’eau et de leur concentration dans les turbulences de sillage a été proposée. Ensuite, deux simulateurs de réponse radar des gouttes d’eau dans et autour des vortex ont été proposés. Ces deux simulateurs ont été utilisés pour reproduire des configurations expérimentales, et une comparaison préliminaire avec les mesures a montré une concordance intéressante entre mesures et simulations en bande X et W. Enfin, l’interprétation de la signature radar des gouttes de pluie dans les vortex a été présentée. La dépendance de la signature envers différents paramètres, à savoir l’intensité de précipitation, la circulation des vortex et les paramètres radar, a été étudiée pour des turbulences de sillage générées par différents types d’avions. Une méthode de détection des turbulences de sillage basée sur la largeur du spectre Doppler des gouttes de pluie et un algorithme permettant d’estimer les caractéristiques des turbulences de sillage ont été proposées. La signature radar des turbulences de sillage par temps de pluie a été modélisée et analysée dans cette thèse. Les résultats de simulations ont démontré les capacités du radar pour la détection de ces turbulences. Les méthodes développées dans cette thèse pourront être utilisées pour le dimensionnement de systèmes radar dédiés à la surveillance des turbulences de sillage par temps de pluie
Nvestigation on radar monitoring of wake vortices in rainy weather is of both scientific and practical interests. This topic hasbeen tackled through three successive steps during this thesis.Firstly, the motion of raindrops in wake vortices has been modeled and simulated. The equation of the motion has been derived and the methodology to compute the raindrops' trajectory and distribution in the flow induced by the wakevortices has been proposed. Secondly, two simulators have been developed for evaluating the radar signatures of raindropsin wake vortices. Those simulators have been used to reproduce experimental configurations and the comparison betweenmeasured and simulated signature has shown an interesting agreement at X and W band. Lastly, the interpretation of radarsignatures of raindrops in wake vortices has been presented. The dependence of radar signatures on rain rate, vortexcirculation and radar parameters has been studied. A wake vortex detection method based on the analysis of Dopplerspectrum width of raindrops and a methodology to estimate the wake vortex characteristics have been proposed.The radar signatures of wake vortices in rainy weather have been modeled and analyzed in this thesis. The simulationresults have demonstrated the capability of radar to detect wake vortex in rainy weather. The methodologies developed inthis thesis can be further exploited for designing new wake vortex radar systems
APA, Harvard, Vancouver, ISO, and other styles
8

Sengupta, Nina. "Detection and prediction of biodiversity patterns as a rapid assessment tool in the tropical forest of East Usambara, Eastern Arc Mountains, Tanzania." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/30272.

Full text
Abstract:
As a strategy to conserve tropical rainforests of the East Usambara block of the Eastern Arc Mountains, Tanzania, I developed a set of models that can identify above-average tree species richness areas within the humid forests. I developed the model based on geo-referenced field data and satellite image-based variables from the Amani Nature Reserve, the largest forest sector in the East Usambara. I then verified the model by applying it to the Nilo Forest Reserve. The field data, part of the Tanzanian National Biodiversity Database, were collected by Frontier-Tanzania between 1999 and 2001, through the East Usambara Conservation Area Management Program, Government of Tanzania. The field data used are rapidly collectible by people with varied backgrounds and education. I gathered spectral reflectance values from pixels in the Landsat Enhanced Thematic Mapper (Landsat ETM) image covering the study area that corresponded to the ground sample points. The spectral information from different bands formed the satellite image-based variables in the dataset. The best satellite image logistic regression and discriminant analysis models were based on a single band, raw Landsat ETM mid-infrared band 7 (RB7). In the Amani forest, the RB7-based model resulted in 65.3% overall accuracy in identifying above average tree species locations. When the logistic and discriminant models were applied to Nilo forest sector, the overall accuracy was 62.3%. Of the rapidly collectible field variables, only tree density (number of trees) was selected in the logistic regression and the discriminant analysis models. Logistic and discriminant models using both RB7 and number of trees recorded 76.3% overall accuracy in Amani, and when applied to Nilo, 76.8% accuracy. It is possible to apply and adapt the current set of models to identify above-average tree species richness areas in East Usambara and other forest blocks of the Eastern Arc Mountains. Potentially, managers and researchers can periodically use the model to rapidly assess, monitor, update, and map the tree species rich areas within the forest. The same or similar models could be applied to check their applicability in other humid tropical forest areas.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
9

Friberg, Carol Diane. "Preliminary processing and evaluation of radar measurements in satellite-path propagation research." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45722.

Full text
Abstract:
Rain and other precipitation cause attenuation and depolarization of high frequency satellite signals. Some characteristics of rain can be measured by dual-polarized radar. These characteristics can then be used to predict the effects of the rain on satellite-path propagation. This thesis describes briefly the theory of radar and satellite link measurements. Methods for calibrating the equipment and deriving actual experimental values from measured power are presented in detail. A set of computer programs to approximately predict radar and link values from measured rain rate are developed. Predicted and measured values may then be compared by a researcher to evaluate system operation and assess the importance of the event data. A discussion of the use of sampled data and these comparisons concludes the report.
Master of Science
APA, Harvard, Vancouver, ISO, and other styles
10

Tang, Shengjie. "Rail Platform Obstacle Detection Using LabVIEW Simulation." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-19063.

Full text
Abstract:
As the rapid development of the rail transportation industry, rail transportation becomes more popular as a component of urban public transport systems, but the fallen obstacle(s) from the rail platform becomes the terrible hidden danger for the rail transportation. As an enclosed public transport systems, rail transportation creates gathered crowd both on board and on the platform. Although railway is the safest form of land transportation, it is capable of producing lots of casualties, when there is an accident.There are several conventional systems of obstacles detection in platform monitoring systems like stereo visions, thermal scanning, and vision metric scanning, etc. As the traditional detection systems could not achieve the demand of detecting the obstacles on the rail within the platform. In this thesis, the author designs a system within the platform based on laser sensors, virtual instruments technology, and image processing technology (machine vision) to increase the efficiency of detection system. The system is useful for guarantying the safety of rail vehicle when coming into the platform and avoid obstacle(s) on the rail fallen from the platform, having a positive impact on traffic safety to protect lives of people.The author used LabVIEW software to create a simulation environment where the input blocks represent the functionalities of the system, in which simulated train detection and fallen object detection. In this thesis, the author mainly focuses on fallen object detection. For fallen object detection, the author used 2D image processing method to detect obstacle(s), so the function is, before the rail vehicle comes into the platform, the system could detect whether there is fallen obstacle(s) on the rail within the platform, simultaneously categorize size of the obstacle(s), and then alarm for delivering the results.
APA, Harvard, Vancouver, ISO, and other styles
11

Bhaduri, Sreyoshi. "Algorithm to enable intelligent rail break detection." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/78080.

Full text
Abstract:
Wavelet intensity based algorithm developed previously at VirginiaTech has been furthered and paired with an SVM based classifier. The wavelet intensity algorithm acts as a feature extraction algorithm. The wavelet transform is an effective tool as it allows one to narrow down upon the transient, high frequency events and is able to tell their exact location in time. According to prior work done in the field of signal processing, the local regularities of a signal can be estimated using a Lipchitz exponent at each time step of the signal. The local Lipchitz exponent can then be used to generate the wavelet intensity factor values. For each vertical acceleration value, corresponding to a specific location on the track, we now have a corresponding intensity factor. The intensity factor corresponds to break-no break information and can now be used as a feature to classify the vertical acceleration as a fault or no fault. Support Vector Machines (SVM) is used for this binary classification task. SVM is chosen as it is a well-studied topic with efficient implementations available. SVM instead of hard threshold of the data is expected to do a better job of classification without increasing the complexity of the system appreciably.
Master of Science
APA, Harvard, Vancouver, ISO, and other styles
12

Shrestha, Survesh Bahadur. "Defect Detection on Rail Base Area Using Infrared Thermography." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2758.

Full text
Abstract:
This research aims to investigate the application of infrared thermography (IRT) as a method of nondestructive evaluation (NDE) for the detection of defects in the rail base area. Rails have to withstand harsh conditions during their application. Therefore, defects can develop in the base area of rails due to stresses such as bending, shear, contact, and thermal stresses, fatigue, and corrosion. Such defects can cause catastrophic failures in the rails, ultimately leading to train derailments. Rail base defects due to fatigue and corrosion are difficult to detect and currently there are no reliable or practical non-destructive evaluation (NDE) methods for finding these types of defects in the revenue service. Transportation Technology Center, Inc. (TTCI) had previously conducted a research on the capability of flash IRT to detect defects in rail base area based on simulation approach. The research covered in this thesis is the continuation of the same project.In this research, three rail samples were prepared with each containing a notched-edge, side-drilled holes (SDHs), and bottom-drilled holes (BDHs). Two steel sample blocks containing BDHs and SDHs of different sizes and depths were also prepared. Preliminary IRT trials were conducted on the steel samples to obtain an optimal IRT setup configuration. The initial inspections for one of the steel samples were outsourced to Thermal Wave Imaging (TWI) where they employed Thermographic Signal Reconstruction (TSR) technique to enhance the resulting images. Additional inspections of the steel samples were performed in the Southern Illinois University-Carbondale (SIUC) facility. In case of the rail samples, the SDHs and the notched-edge reflectors could not be detected in any of the experimental trials performed in this research. In addition, two more rail samples containing BDHs were prepared to investigate the detection capabilities for three different surface conditions: painted, unpainted, and rusted. The painted surface provided a best-case scenario for inspections while the other conditions offered further insight on correlating the application to industry-like cases.A 1300 W halogen lamp was employed as the heat source for providing continuous thermal excitation for various durations. Post-processing and analysis of the resulting thermal images was performed within the acquisition software using built-in analysis tools such as temperature probes, Region of Interest (ROI) based intensity profiles, and smoothing filters. The minimum defect diameter to depth (aspect) ratio detected in preliminary trials for the steel sample blocks were 1.0 at a diameter of 4.7625 mm (0.1875 in) and 1.5 at a diameter of 3.175 mm (0.125 in). For the inspection of painted rail sample, the longest exposure times (10 sec) provided the best detection capabilities in all sets of trials. The three holes having aspect ratio greater or equal to 1.0 were indicated in the thermal response of the painted and rusted samples while only the two holes having aspect ratio greater or equal to 1.5 were indicated in the unaltered sample. Indications of reflectors were identified through qualitative graphical analysis of pixel intensity distributions obtained along a bending line profile. The results obtained from the painted sample provided a baseline for analyzing the results from the unpainted and rusted rail samples. This provided an insight on the limitations and requirements for future development. The primary takeaway is the need for an optimized heat source. Poor contrast in the resulting image for the unpainted and rusted rail samples is experienced due to both noise and lack of penetration of the heat energy. This could have been due to decreased emissivity values. Moreover, the excitation method employed in this research does not comply with current industry standards for track clearances. Therefore, exploration of alternative excitation methods is recommended.
APA, Harvard, Vancouver, ISO, and other styles
13

Hopkins, Brad Michael. "A Wavelet-Based Rail Surface Defect Prediction and Detection Algorithm." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77351.

Full text
Abstract:
Early detection of rail defects is necessary for preventing derailments and costly damage to the train and railway infrastructure. A rail surface flaw can quickly propagate from a small fracture to a broken rail after only a few train cars have passed over it. Rail defect detection is typically performed by using an instrumented car or a separate railway monitoring vehicle. Rail surface irregularities can be measured using accelerometers mounted to the bogie side frames or wheel axles. Typical signal processing algorithms for detecting defects within a vertical acceleration signal use a simple thresholding routine that considers only the amplitude of the signal. As a result, rail surface defects that produce low amplitude acceleration signatures may not be detected, and special track components that produce high amplitude acceleration signatures may be flagged as defects. The focus of this research is to develop an intelligent signal processing algorithm capable of detecting and classifying various rail surface irregularities, including defects and special track components. Three algorithms are proposed and validated using data collected from an instrumented freight car. For the first two algorithms, one uses a windowed Fourier Transform while the other uses the Wavelet Transform for feature extraction. Both of these algorithms use an artificial neural network for feature classification. The third algorithm uses the Wavelet Transform to perform a regularity analysis on the signal. The algorithms are validated with the collected data and shown to out-perform the threshold-based algorithm for the same data set. Proper training of the defect detection algorithm requires a large data set consisting of operating conditions and physical parameters. To generate this training data, a dynamic wheel-rail interaction model was developed that relates defect geometry to the side frame vertical acceleration signature. The model was generated by using combined systems dynamic modeling, and the system was solved with a developed combined lumped and distributed parameter system numerical approximation. The broken rail model was validated with real data collected from an instrumented freight car. The model was then used to train and validate the defect detection methodologies for various train and rail physical parameters and operating conditions.
Ph. D.
APA, Harvard, Vancouver, ISO, and other styles
14

Duthon, Pierre. "Descripteurs d'images pour les systèmes de vision routiers en situations atmosphériques dégradées et caractérisation des hydrométéores." Thesis, Université Clermont Auvergne‎ (2017-2020), 2017. http://www.theses.fr/2017CLFAC065/document.

Full text
Abstract:
Les systèmes de vision artificielle sont de plus en plus présents en contexte routier. Ils sont installés sur l'infrastructure, pour la gestion du trafic, ou placés à l'intérieur du véhicule, pour proposer des aides à la conduite. Dans les deux cas, les systèmes de vision artificielle visent à augmenter la sécurité et à optimiser les déplacements. Une revue bibliographique retrace les origines et le développement des algorithmes de vision artificielle en contexte routier. Elle permet de démontrer l'importance des descripteurs d'images dans la chaîne de traitement des algorithmes. Elle se poursuit par une revue des descripteurs d'images avec une nouvelle approche source de nombreuses analyses, en les considérant en parallèle des applications finales. En conclusion, la revue bibliographique permet de déterminer quels sont les descripteurs d'images les plus représentatifs en contexte routier. Plusieurs bases de données contenant des images et les données météorologiques associées (ex : pluie, brouillard) sont ensuite présentées. Ces bases de données sont innovantes car l'acquisition des images et la mesure des conditions météorologiques sont effectuées en même temps et au même endroit. De plus, des capteurs météorologiques calibrés sont utilisés. Chaque base de données contient différentes scènes (ex: cible noir et blanc, piéton) et divers types de conditions météorologiques (ex: pluie, brouillard, jour, nuit). Les bases de données contiennent des conditions météorologiques naturelles, reproduites artificiellement et simulées numériquement. Sept descripteurs d'images parmi les plus représentatifs du contexte routier ont ensuite été sélectionnés et leur robustesse en conditions de pluie évaluée. Les descripteurs d'images basés sur l'intensité des pixels ou les contours verticaux sont sensibles à la pluie. A l'inverse, le descripteur de Harris et les descripteurs qui combinent différentes orientations sont robustes pour des intensités de pluie de 0 à 30 mm/h. La robustesse des descripteurs d'images en conditions de pluie diminue lorsque l'intensité de pluie augmente. Finalement, les descripteurs les plus sensibles à la pluie peuvent potentiellement être utilisés pour des applications de détection de la pluie par caméra.Le comportement d'un descripteur d'images en conditions météorologiques dégradées n'est pas forcément relié à celui de la fonction finale associée. Pour cela, deux détecteurs de piéton ont été évalués en conditions météorologiques dégradées (pluie, brouillard, jour, nuit). La nuit et le brouillard sont les conditions qui ont l'impact le plus important sur la détection des piétons. La méthodologie développée et la base de données associée peuvent être utilisées à nouveau pour évaluer d'autres fonctions finales (ex: détection de véhicule, détection de signalisation verticale).En contexte routier, connaitre les conditions météorologiques locales en temps réel est essentiel pour répondre aux deux enjeux que sont l'amélioration de la sécurité et l'optimisation des déplacements. Actuellement, le seul moyen de mesurer ces conditions le long des réseaux est l'installation de stations météorologiques. Ces stations sont coûteuses et nécessitent une maintenance particulière. Cependant, de nombreuses caméras sont déjà présentes sur le bord des routes. Une nouvelle méthode de détection des conditions météorologiques utilisant les caméras de surveillance du trafic est donc proposée. Cette méthode utilise des descripteurs d'images et un réseau de neurones. Elle répond à un ensemble de contraintes clairement établies afin de pouvoir détecter l'ensemble des conditions météorologiques en temps réel, mais aussi de pourvoir proposer plusieurs niveaux d'intensité. La méthode proposée permet de détecter les conditions normales de jour, de nuit, la pluie et le brouillard. Après plusieurs phases d'optimisation, la méthode proposée obtient de meilleurs résultats que ceux obtenus dans la littérature, pour des algorithmes comparables
Computer vision systems are increasingly being used on roads. They can be installed along infrastructure for traffic monitoring purposes. When mounted in vehicles, they perform driver assistance functions. In both cases, computer vision systems enhance road safety and streamline travel.A literature review starts by retracing the introduction and rollout of computer vision algorithms in road environments, and goes on to demonstrate the importance of image descriptors in the processing chains implemented in such algorithms. It continues with a review of image descriptors from a novel approach, considering them in parallel with final applications, which opens up numerous analytical angles. Finally the literature review makes it possible to assess which descriptors are the most representative in road environments.Several databases containing images and associated meteorological data (e.g. rain, fog) are then presented. These databases are completely original because image acquisition and weather condition measurement are at the same location and the same time. Moreover, calibrated meteorological sensors are used. Each database contains different scenes (e.g. black and white target, pedestrian) and different kind of weather (i.e. rain, fog, daytime, night-time). Databases contain digitally simulated, artificial and natural weather conditions.Seven of the most representative image descriptors in road context are then selected and their robustness in rainy conditions is evaluated. Image descriptors based on pixel intensity and those that use vertical edges are sensitive to rainy conditions. Conversely, the Harris feature and features that combine different edge orientations remain robust for rainfall rates ranging in 0 – 30 mm/h. The robustness of image features in rainy conditions decreases as the rainfall rate increases. Finally, the image descriptors most sensitive to rain have potential for use in a camera-based rain classification application.The image descriptor behaviour in adverse weather conditions is not necessarily related to the associated final function one. Thus, two pedestrian detectors were assessed in degraded weather conditions (rain, fog, daytime, night-time). Night-time and fog are the conditions that have the greatest impact on pedestrian detection. The methodology developed and associated database could be reused to assess others final functions (e.g. vehicle detection, traffic sign detection).In road environments, real-time knowledge of local weather conditions is an essential prerequisite for addressing the twin challenges of enhancing road safety and streamlining travel. Currently, the only mean of quantifying weather conditions along a road network requires the installation of meteorological stations. Such stations are costly and must be maintained; however, large numbers of cameras are already installed on the roadside. A new method that uses road traffic cameras to detect weather conditions has therefore been proposed. This method uses a combination of a neural network and image descriptors applied to image patches. It addresses a clearly defined set of constraints relating to the ability to operate in real-time and to classify the full spectrum of meteorological conditions and grades them according to their intensity. The method differentiates between normal daytime, rain, fog and normal night-time weather conditions. After several optimisation steps, the proposed method obtains better results than the ones reported in the literature for comparable algorithms
APA, Harvard, Vancouver, ISO, and other styles
15

Nouri, Arash. "Correlation-Based Detection and Classification of Rail Wheel Defects using Air-coupled Ultrasonic Acoustic Emissions." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78139.

Full text
Abstract:
Defected wheel are one the major reasons endangered state of railroad vehicles safety statue, due to vehicle derailment and worsen the quality of freight and passenger transportation. Therefore, timely defect detection for monitoring and detecting the state of defects is highly critical. This thesis presents a passive non-contact acoustic structural health monitoring approach using ultrasonic acoustic emissions (UAE) to detect certain defects on different structures, as well as, classifying the type of the defect on them. The acoustic emission signals used in this study are in the ultrasonic range (18-120 kHz), which is significantly higher than the majority of the research in this area thus far. For the proposed method, an impulse excitation, such as a hammer strike, is applied to the structure. In addition, ultrasound techniques have higher sensitivity to both surface and subsurface defects, which make the defect detection more accurate. Three structures considered for this study are: 1) a longitudinal beam, 2) a lifting weight, 3) an actual rail-wheel. A longitudinal beam was used at the first step for a better understanding of physics of the ultrasound propagation from the defect, as well, develop a method for extracting the signature response of the defect. Besides, the inherent directionality of the ultrasound microphone increases the signal to noise ratio (SNR) and could be useful in the noisy areas. Next, by considering the ultimate goal of the project, lifting weight was chosen, due to its similarity to the ultimate goal of this project that is a rail-wheel. A detection method and metric were developed by using the lifting weight and two type of synthetic defects were classified on this structure. Also, by using same extracted features, the same types of defects were detected and classified on an actual rail-wheel.
Master of Science
APA, Harvard, Vancouver, ISO, and other styles
16

Rani, Dipti [Verfasser]. "Label-free detection of biomolecules using silicon nanowire ion-sensitive field-effect transistor devices / Dipti Rani." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1156851343/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
17

Singh, Dejah Leandra. "The Application of Laser Technology for Railroad Top of Rail (TOR) Friction Modifier Detection and Measurements." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83234.

Full text
Abstract:
The examination of the application and accuracy of optical sensors for the purpose of determining rail lubricity of top-of-rail friction modifier is investigated in this research. A literature review of optical sensors as they relate to detecting thin layers is presented, as well as a literature review of the significant aspect of surface roughness on optical signature. Both commercially available optical sensors and optical devices, such as independent lasers and detectors, are examined in a comprehensive parametric study to determine the most suitable configuration for a prototype with adequate third-body detection. A prototype is constructed considering parameters such as sunlight contamination, vibrations, and angle of detection. The prototype is evaluated in a series of laboratory tests with known lubricity conditions for its accuracy of measurements and susceptibility to environmental conditions, in preparation for field testing. Upon field testing the prototype, the data indicates that it is capable of providing subjective measurements that can help with determining whether a rail is highly lubricated or unlubricated, or it is moderately lubricated. It is anticipated that the device could be used to provide a rail lubricity index. The investigation of the optical response of a rail in various conditions, including top-of-rail friction modifier presence and underlying surface roughness, reveals the behavior of friction modifying material on rail/wheel interactions. It is determined that surface roughness is imperative for distinguishing between scattering due to surface condition and scattering due to third-body layers. Additionally it is revealed that friction modifying materials become entrapped within the surface roughness of the rail, effectively causing a "seasoning" effect instead of a simple third body layer. This provides some explanation on the inadequacy of determining lubricity conditions using contacting methods since they cannot detect the entrapped material that are revealed only when the top of rail undergoes a micro deformation due to a passing wheel. Furthermore, the fluorescent signature of flange grease can be utilized to detect any flange grease contamination on top of rail. The results of the study indicate that it is possible to have practical optical sensors for top-of-rail third body layer detection and any contamination that may exist, initially through spot checking the rail and eventually through in-motion surveying.
Master of Science
APA, Harvard, Vancouver, ISO, and other styles
18

Halmaoui, Houssam. "Restauration d'images par temps de brouillard et de pluie : applications aux aides à la conduite." Phd thesis, Université d'Evry-Val d'Essonne, 2012. http://tel.archives-ouvertes.fr/tel-00830869.

Full text
Abstract:
Les systèmes d'aide à la conduite (ADAS) ont pour objectif d'assister le conducteur et en particulier d'améliorer la sécurité routière. Pour cela, différents capteurs sont généralement embarqués dans les véhicules afin, par exemple, d'avertir le conducteur en cas de danger présent sur la route. L'utilisation de capteurs de type caméra est une solution économiquement avantageuse et de nombreux ADAS à base de caméra voient le jour. Malheureusement, les performances de tels systèmes se dégradent en présence de conditions météorologiques défavorables, notamment en présence de brouillard ou de pluie, ce qui obligerait à les désactiver temporairement par crainte de résultats erronés. Hors, c'est précisément dans ces conditions difficiles que le conducteur aurait potentiellement le plus besoin d'être assisté. Une fois les conditions météorologiques détectées et caractérisées par vision embarquée, nous proposons dans cette thèse de restaurer l'image dégradée à la sortie du capteur afin de fournir aux ADAS un signal de meilleure qualité et donc d'étendre la gamme de fonctionnement de ces systèmes. Dans l'état de l'art, il existe plusieurs approches traitant la restauration d'images, parmi lesquelles certaines sont dédiées à nos problématiques de brouillard ou de pluie, et d'autres sont plus générales : débruitage, rehaussement du contraste ou de la couleur, "inpainting"... Nous proposons dans cette thèse de combiner les deux familles d'approches. Dans le cas du brouillard notre contribution est de tirer profit de deux types d'approches (physique et signal) afin de proposer une nouvelle méthode automatique et adaptée au cas d'images routières. Nous avons évalué notre méthode à l'aide de critères ad hoc (courbes ROC, contraste visibles à 5 %, évaluation sur ADAS) appliqués sur des bases de données d'images de synthèse et réelles. Dans le cas de la pluie, une fois les gouttes présentes sur le pare-brise détectées, nous reconstituons les parties masquées de l'image à l'aide d'une méthode d'"inpainting" fondée sur les équations aux dérivées partielles. Les paramètres de la méthode ont été optimisés sur des images routières. Enfin, nous montrons qu'il est possible grâce à cette approche de construire trois types d'applications : prétraitement, traitement et assistance. Dans chaque famille, nous avons proposé et évalué une application spécifique : détection des panneaux dans le brouillard ; détection de l'espace navigable dans le brouillard ; affichage de l'image restaurée au conducteur.
APA, Harvard, Vancouver, ISO, and other styles
19

Jehangiri, Ali Imran Verfasser], Ramin [Akademischer Betreuer] Yahyapour, Andrei [Akademischer Betreuer] [Tchernykh, Carsten [Akademischer Betreuer] Damm, Xiaoming [Akademischer Betreuer] Fu, Dieter [Akademischer Betreuer] Hogrefe, and Winfried [Akademischer Betreuer] Kurth. "Distributed Anomaly Detection and Prevention for Virtual Platforms / Ali Imran Jehangiri. Gutachter: Ramin Yahyapour ; Andrei Tchernykh ; Carsten Damm ; Xiaoming Fu ; Dieter Hogrefe ; Winfried Kurth. Betreuer: Ramin Yahyapour." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/107475848X/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
20

Gulán, Filip. "Detekce, lokalizace a určení plochy chronických ran." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2018. http://www.nusl.cz/ntk/nusl-385966.

Full text
Abstract:
The aim of this diploma thesis is to design and implement a multiplatform application for detection, localization and determination of the extent of chronic wounds. The application is intended to assist nurses, doctors and healthcare assistants to monitor and evaluate chronic wounds in the course of treatment. The application is based on the Typescript programming language, on the Ionic hybrid application framework and on the Electron desktop application framework. Chronic wound assessment runs on the server-side where the Python programming language is used. The Flask application framework is used for the RESTful application interface and the OpenCV library is used for image processing.
APA, Harvard, Vancouver, ISO, and other styles
21

Giard, Martin. "Mesure de l'emission diffuse galactique dans la raie a 3,3 micrometre avec l'experience ballon arome." Toulouse 3, 1988. http://www.theses.fr/1988TOU30143.

Full text
Abstract:
Presentation de l'experience arome, embarquee en ballon stratospherique et dont l'objectif est la detection dans le flux diffus de la galaxie des raies d'emission a 3. 3, 6. 2, 7. 7 et 11. 3 mu m. Cette famille de raies caracterise la presence de composes aromatiques polycycliques (pah). L'objet du premier vol a ete constitue par l'observation a 3. 3 mu m et des cartes couvrant les coordonnees galactiques 6**(o)
APA, Harvard, Vancouver, ISO, and other styles
22

Norris, Natasha Louise. "Implementation of Multi-Constellation Baseline Fault Detection and Exclusion Algorithm Utilizing GPS and GLONASS Signals." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1535028817622931.

Full text
APA, Harvard, Vancouver, ISO, and other styles
23

Schwarz, Brandon A. (Brandon Alexander). "Evaluation of a methodology for detecting railroad track geometry anomalies and determining rail vehicle fatigue loads." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12401.

Full text
APA, Harvard, Vancouver, ISO, and other styles
24

Aydos, Gökçe [Verfasser], Görschwin [Akademischer Betreuer] [Gutachter] Fey, and Jaan [Gutachter] Raik. "Parity-based Error Detection with Recomputation for Fault-tolerant Spaceborne Computing / Gökçe Aydos ; Gutachter: Görschwin Fey, Jaan Raik ; Betreuer: Görschwin Fey." Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/1140581732/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
25

Nallaivarothayan, Hajananth. "Video based detection of normal and anomalous behaviour of individuals." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/106947/1/Hajananth_Nallaivarothayan_Thesis.pdf.

Full text
Abstract:
This PhD research has proposed novel computer vision and machine learning algorithms for the problem of video based anomalous event detection of individuals. Varieties of Hidden Markov Models were designed to model the temporal and spatial causalities of crowd behaviour. A Markov Random Field on top of a Gaussian Mixture Model is proposed to incorporate spatial context information during classification. Discriminative conditional random field methods are also proposed. Novel features are proposed to extract motion and appearance information. Most of the proposed approaches comprehensively outperform other techniques on publicly available datasets during the time of publications originating from the results.
APA, Harvard, Vancouver, ISO, and other styles
26

Workman, Simon. ""A Criminal Strain Ran In His Blood": Biomedical Science, Criminology, and Empire in the Sherlock Holmes Canon." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1505126689988603.

Full text
APA, Harvard, Vancouver, ISO, and other styles
27

Kováč, Michal. "ANALÝZA MOŽNOSTÍ SIMULÁCIE A IMPLEMENTÁCIE AUTOSYNCHRÓNNYCH SUBSYSTÉMOV V OBVODOCH VLSI." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-233515.

Full text
Abstract:
This thesis focuses on problem-solution analysis of synchronous digital circuits; the results of which are autosynchronous circuit design methodology, timing parameter definitions based on simulation models and constraint settings. The RTL transformation of the synchronous state machine in VHDL language to an autosynchronous state machine was created with minimal modifications for the simple design of these circuits. Following this, a comparison of the transformed state machines with their synchronous originals in parameters such as chip area, current consumption and timing specification domain is introduced. The summation of this thesis displays a theoretical comparison of several types of synchronization (synchronous, autosynchronous, fundamental asynchronous, EAIC, Bundled-data, Dual-rail) which are presented on the single state machine example with the same technology parameters.
APA, Harvard, Vancouver, ISO, and other styles
28

Glisson, Wesley J., Courtney J. Conway, Christopher P. Nadeau, and Kathi L. Borgmann. "Habitat models to predict wetland bird occupancy influenced by scale, anthropogenic disturbance, and imperfect detection." WILEY, 2017. http://hdl.handle.net/10150/625200.

Full text
Abstract:
Understanding species-habitat relationships for endangered species is critical for their conservation. However, many studies have limited value for conservation because they fail to account for habitat associations at multiple spatial scales, anthropogenic variables, and imperfect detection. We addressed these three limitations by developing models for an endangered wetland bird, Yuma Ridgway's rail (Rallus obsoletus yumanensis), that examined how the spatial scale of environmental variables, inclusion of anthropogenic disturbance variables, and accounting for imperfect detection in validation data influenced model performance. These models identified associations between environmental variables and occupancy. We used bird survey and spatial environmental data at 2473 locations throughout the species' U.S. range to create and validate occupancy models and produce predictive maps of occupancy. We compared habitat-based models at three spatial scales (100, 224, and 500 m radii buffers) with and without anthropogenic disturbance variables using validation data adjusted for imperfect detection and an unadjusted validation dataset that ignored imperfect detection. The inclusion of anthropogenic disturbance variables improved the performance of habitat models at all three spatial scales, and the 224-m-scale model performed best. All models exhibited greater predictive ability when imperfect detection was incorporated into validation data. Yuma Ridgway's rail occupancy was negatively associated with ephemeral and slow-moving riverine features and high-intensity anthropogenic development, and positively associated with emergent vegetation, agriculture, and low-intensity development. Our modeling approach accounts for common limitations in modeling species-habitat relationships and creating predictive maps of occupancy probability and, therefore, provides a useful framework for other species.
APA, Harvard, Vancouver, ISO, and other styles
29

Santos, Narciso Ferreira. "Contaminação do ar ambiental por radônio e filhos : estudo de características do 220Rn e filhos utilizando o detector CR-39." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278106.

Full text
Abstract:
Orientador: Julio Cesar Hadler Neto
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
Made available in DSpace on 2018-08-03T13:45:16Z (GMT). No. of bitstreams: 1 Santos_NarcisoFerreira_D.pdf: 3163623 bytes, checksum: b1421a9ac7f2e1a74969770dd60e8db1 (MD5) Previous issue date: 2003
Resumo: O objetivo desse trabalho foi o de caracterizar o detector de traços nucleares de estado sólido CR-39 para uma espectroscopia alfa adequada à medição das atividades do radônio e filhos, separando-se a atividade de 222Rn e filhos da atividade de 220Rn e filhos. Foi obtida a atividade do 222Rn separada da atividade do 220Rn mediante a exposição do CR-39 em uma seqüência regularmente espaçada de filmes finos de ar. Obtivemos um diagrama de tamanhos de traços e densidade óptica que distingue de forma inequívoca os traços produzidos por filhos de cada uma das cadeias. Obtivemos ainda uma medida da atividade dos filhos do 220Rn referidas à atividade do 222Rn em um ambiente sem ventilação. Para obter estes resultados produzimos uma fonte de chumbo 212 e construímos um dispositivo adequado à calibração do CR-39, para espectroscopia alfa. Indicamos um caminho para estender o método também a ambientes ventilados
Abstract: The aim of this work was to characterize the solid state nuclear track detector CR-39 to do an alpha spectroscopy suitable for measuring radon and radon daughter activities, distinguishing between 222Rn and daughters and 220Rn and daughters. The 222Rn and 220Rn activities were obtained separately through a regular sequence of thin films of air. We obtained diagrams of track size and optical density, which unequivocally distinguish the tracks yielded by daughters of each decay chain. We obtained a measurement of the 220Rn daughters¿ activity relative to the 222Rn activity in an environment without ventilation. In order to obtain these results we manufactured a lead-212 source and a device suitable for the calibration of the CR-39 for alpha spectroscopy. Finally, we give directions for applying the method also in ventilated environments
Doutorado
Física
Doutor em Ciências
APA, Harvard, Vancouver, ISO, and other styles
30

Schilling, Alexander. "Model-based detection and isolation of faults in the air and fuel paths of common-rail DI diesel engines equipped with a lambda and a nitrogen oxides sensor /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17764.

Full text
APA, Harvard, Vancouver, ISO, and other styles
31

Monguilhott, Michele. "Avaliação de alterações na superfície agrícola a partir da técnica RCEN, em municípios do território da cidadania região central/RS." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/155987.

Full text
Abstract:
Pour l’analyse de la dynamique territoriale il est fondamental une grande quantité de données et leur intégration avec des données spatiales et statistiques facilite ce processus. La thèse se propose d’analyser la dynamique de la superficie agricole des municipalités du Territoire de la Citoyenneté Região Central-RS (TCRCRS) qui fait partie d’une politique publique spatiale de territoires citoyens. Cette dynamique sera analysée à partir d’une technique de détection de changement connue par Rotation Contrôlée par Axe de Non Changement - RCEN. Ainsi, la thèse a comme objectif évaluer les altérations subies par la superficie agricole au long de la période 1985 / 2010 dans les municipalités du TCRCRS en utilisant l’algorithme RCEN. Les étapes méthodologiques suivantes ont été implémentées: utilisation d’images différentes pour l’obtention de pixeis échantillons de non changement; analyse qualitative de l’organisation de la superficie agricole pour les municipalités de Cacequi, Santiago et Tupanciretã, sélectionnés en raison de leur localisation parmi des différentes sous-unités de paysage dans l’État; définition des seuils pour la délimitation des classes thématiques de l’organisation spatiale de la superficie agricole et évaluation de la fiabilité des résultats de la technique RCEN, utilisée pour déterminer la précision de la classification supervisée des images TM Landsat 5 par une matrice de concaténation. La matrice est basée sur l’algèbre de cartes de façon à obtenir une image numérique finale qui exprime toutes les possibilités de l’espace échantillon. Les résultats ont montré que, avec 1% de signification, la technique RCEN peut être utilisée pour détecter la dynamique dans la superficie agricole en utilisant les seuils de vigueur végétatif de l’IDETEC comparés aux résultats des répertoires Normalized Difference Vegetation Index (NDVI), qui a été obtenu tout en considérant le total de pluies antérieures au passage du senseur, variable qui interfère sur les valeurs moyennes de NDVI. Des images de détections de changements (IDETEC) ont été engendrées pour analyser les cultures agricoles d’hiver et d’été, s’obtenant 99% de confiance en les images choisies pour la distribution spatiale des classes définies par l’adoption des seuils de ( - 0,5σ ; – 1,5σ ; + 0,5σ ; + 1,5σ), en prenant comme point central de la classe de non changement. Les images de détection de changements ont permis d’estimer et de comparer les classes de l’IDETEC avec les estimations du total d’aire plantée de cultures temporaires et des cultures agricoles de riz, avoine, maïs, soja et blé. Les aires obtenues par l’IDETEC à Tupanciretã ont surestimé l’aire agricole présentée par l’IBGE dans les images d’été avec des variations en pourcentages entre 1,11% dans l’IDETEC 1994/2009 et 8,13% dans l’IDETEC 2004/2010 ; pour les images d’hiver l’altération a été de 9,46% dans l’IDETEC 1989/2007 et de 3,44% dans l’IDETEC 1996/2005. À la municipalité de Cacequi, les variations en pourcentages de cultures temporaires ont été surestimées dans les images d’été en 7,71% dans l’IDETEC 1986/2006 et 20,47% dans l’IDETEC 1993/2005 et sous-estimées dans les images d’hiver en 9,42% dans l’IDETEC 1985/2003 et en 18,11% dans l’IDETEC 1996/2007. À Santiago elles ont été sous-estimées pour la période d’été en 24,76% dans l’IDETEC 1984/2009, pour la période d’hiver en 10,52% dans l’IDETEC 1996/2005 et surestimées en 8,23% dans l’IDETEC 2004/2010 et en 26,12% pour l’image d’hiver IDETEC 1989/2007. La technique RCEN a prouvé être capable d’évaluer des altérations dans la superficie agricole de cultures annuelles pour les municipalités de Cacequi, Santiago et Tupanciretã.
Para análise da dinâmica territorial, é fundamental uma grande quantidade de dados e a integração com dados espaciais e estatísticos, facilita esse processo. A tese propõe analisar, a dinâmica da superfície agrícola de municípios do Território da Cidadania Região Central-RS (TCRCRS), território este que, faz parte de uma política pública de territórios da cidadania. Essa dinâmica, será analisada a partir de uma técnica de detecção de mudança, conhecida por Rotação Controlada por Eixo de Não Mudança - RCEN. Assim, a tese objetiva avaliar as alterações na superfície agrícola, no período de 1985 a 2010, em municípios do TCRCRS, utilizando o algoritmo RCEN. As seguintes etapas metodológicas, foram implementadas: utilização de imagens diferentes, para obtenção de pixeis amostrais de não mudança; análise qualitativamente da organização da superfície agrícola, para os municípios de Cacequi, Santiago e Tupanciretã, selecionados por sua localização em diferentes subunidades de paisagem no Estado; definição dos limiares, para delimitação das classes temáticas da organização espacial da superfície agrícola e, avaliação da confiabilidade dos resultados da técnica RCEN, utilizada pra determinar, a precisão da classificação supervisionada das imagens TM Landsat 5, através de uma matriz de concatenação. A matriz, é baseada em álgebra de mapas de tal maneira, a obter uma imagem numérica final que, expresse todas as possibilidades do espaço amostral. Os resultados, mostraram que, com 1% de significância, a técnica RCEN pode ser utilizada, para detectar a dinâmica na superfície agrícola, utilizando limiares de vigor vegetativo da IDETEC, comparados aos resultados dos índices Normalized Difference Vegetation Index (NDVI), que foi obtido considerando, o total de chuvas antecedentes a passagem do sensor, que é uma variável que interfere, nos valores médios de NDVI. Foram geradas imagens de detecção de mudanças (IDETEC), para analisar culturas agrícolas de inverno e de verão, obtendo-se 99% de confiança nas imagens selecionadas, para a distribuição espacial das classes definidas pela adoção dos limiares de ( - 0,5σ; – 1,5σ ; + 0,5σ; + 1,5σ), utilizando a como ponto central da classe de não mudança. As imagens de detecção de mudanças, permitiram estimar e comparar as classes da IDETEC, com as estimativas do total de área plantada, de lavouras temporárias, das culturas agrícolas de arroz, aveia, milho, soja e trigo As áreas obtidas pela IDETEC em Tupanciretã, superestimaram a área agrícola, apresentada pelo IBGE, nas imagens de verão com variações percentuais entre 1,11% na IDETEC 1994/2009 e 8,13% na IDETEC 2004/2010, para as imagens de inverno, a alteração foi de 9,46% na IDETEC 1989/2007 e de 3,44% na IDETEC 1996/2005. No município de Cacequi, as variações percentuais de lavouras temporárias foram superestimadas nas imagens de verão em 7,71% na IDETEC 1986/2006 e 20,47% na IDETEC 1993/2005 e, subestimadas nas imagens de inverno em 9,42% na IDETEC 1985/2003 e em 18,11% na IDETEC 1996/2007. Em Santiago, foram subestimadas para o período de verão em 24,76% na IDETEC 1984/2009 e, para o período de inverno em 10,52%, na IDETEC 1996/2005 e superestimadas em 8,23% na IDETEC 2004/2010 e, em 26,12% para a imagem de inverno IDETEC 1989/2007. A técnica RCEN, demonstrou ser capaz de estimar alterações na superfície agrícola, de culturas anuais para os municípios de Cacequi, Santiago e Tupanciretã.
For the analysis of territorial dynamics, a great amount of data is fundamental, and the integration of spatial and statistical data facilitates this process. This thesis proposes to analyze the dynamic of the agricultural surface in the Citizenship Country in the Central Area of Rio Grande do Sul (CCCARS), a country that is part of a public policy of citizenship countries. This dynamics will be analyzed by a change detection technique, known as Rotation Controlled of Non-change Axis (RCNA).Thus, this thesis aims to evaluate the alterations in the agricultural surface, in the period from 1985 to 2010, in CCCARS cities, using the RCNA algorithm. The following methodological steps were implemented: the use of different images in order to obtain non-change sampling pixeis; qualitative analysis of the organization of the agricultural surface in the cities of Cacequi, Santiago and Tupanciretã, which were selected due to their location in different subunits of landscapes in the State; determination of thresholds for the delimitation of thematic clusters in the spatial organization of the agricultural surface; and the evaluation of the reliability of the results of RCNA technique, which was used to determine the accuracy of the supervised classification of Landsat TM 5 images through a concatenating matrix. The matrix is based on the map algebra in such manner that expresses all the possibilities of the sampling space. The results showed that with 1% of significance, the RCNA technique can be used to detect the dynamics of the agricultural surface using threshold of the vigor of the vegetative growth compared with the results of Normalized Difference Vegetation Index (NDVI), which were obtained considering the total amount of rain previous to the sensor scanning, which is a variable that interferes in the medium values of NDVI. It was created images of changes detection (IDETEC) in order to analyze summer and winter agricultural crops, obtaining 99% of reliability on the selected images, for the special distribution of the defined clusters by the adoption of the threshold values of de ( - 0,5σ; – 1,5σ ; + 0,5σ; + 1,5σ), using the as a central point of nonchange cluster. The change detection images enabled to estimate and compare IDETEC clusters with the estimate of the total planted area of temporary farm, agricultural crop of rice, oat, corn, soybean and wheat. The areas obtained by IDETEC in Tupanciretã overestimated the agricultural area presented by IBGE, with summer images with percentage variance among 1,11% on IDETEC 1994/2009 and 8,13% on IDETEC 2004/2010, for the winter images, the alteration was of 9,46% on IDETEC 1989/2007 and of 3,44% on IDETEC 1996/2007. In the city of Cacequi, the percentage variance of the temporary farms were overestimated on the summer images in 7,71% on IDETEC 1986/2006 and 20,47% on IDETEC 1993/2005 and , and overestimated on the winter images in 9,42% on IDETEC 1985/2003 and in 18,11% on IDETEC 1996/2007. In Santiago, they were underestimated for the summer period in 24,76% on IDETEC 1984/2009 and , for the winter period in 10,52%, on IDETEC 1996/2005 e and overestimated in 8,23% on IDETEC 2004/2010 and, in 26,12% for the winter image IDETEC 1989/2007. The RCNA technique showed itself to be capable of estimating the agricultural surface alteration in annual crops in the cities of Cacequi, Santiago e Tupanciretã.
APA, Harvard, Vancouver, ISO, and other styles
32

Merino, Pierrick. "Reproduction expérimentale du contact roue-rail à échelle réduite : Voies de formation des sources de défauts." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI101.

Full text
Abstract:
Face au développement du transport ferroviaire, la sécurité demeure la principale préoccupation des exploitants de réseaux ferrés. En particulier, la compréhension des phénomènes sources des défauts de fatigue de roulement (RCF) mettant en jeu l’intégrité du rail, est nécessaire pour limiter les risques d’accidents. La phase blanche, associée à la formation du défaut de squat, est difficile à reproduire mécaniquement en laboratoire. L’utilisation de bancs d’essai permet de reproduire plusieurs aspects du contact roue-rail selon des critères choisis, mais nécessite de faire des compromis. Le banc Triboring développé au LaMCoS avec la RATP, comble un manque en proposant notamment une géométrie galet sur rail circulaire pour reproduire au mieux les conditions tribologiques du contact roue-rail. Le développement d’un banc d’essai nécessite d’évaluer sa « signature », c’est-à-dire d’identifier et de discerner les phénomènes mesurés correspondant à la réponse intrinsèque du banc en fonctionnement, de ceux correspondant à la réponse de l’interaction roue-rail considérée. Une analyse notamment dynamique et cinématique a permis de caractériser le banc et d’optimiser sa réponse en faisant évoluer la géométrie des éprouvettes. La réponse tribologique du banc a été optimisée par l’introduction d’une couche qualifiée de « fusible tribologique », lors de la préparation des éprouvettes. Cette couche surfacique permet de retarder l’accommodation des vitesses par usure au profit du cisaillement des premiers corps et des Transformations Tribologiques de Surface (TTS), telles que la phase blanche. Deux couches fusibles, écrouies et corrodées ont été éprouvées, et permettent une nette réduction de l’usure. Les analyses tribologiques et métallurgiques des bandes de roulement en surface et des coupes ont permis d’appréhender l’effet des différentes sollicitations mécaniques sur l’évolution de la microstructure du rail en proche surface. La transformation de cette dernière amène le matériau vers la formation d’îlots de phase blanche d’origine mécanique à la surface
The safety issue is still the main concern of railway network due to the development of railway transportation and the increase of the amount of passengers. The understanding of the origin of the rolling contact fatigue (RCF) defect, is one key to safety requirements. The White Etching Layer associated to the initiation of the squat defect is hardly recreated. The use of laboratory test bench enable the replication of the wheel-rail contact. Nevertheless, only a fraction of the characteristic parameters is taken into account and compromises are necessary. The test bench “Triboring” built at LaMCoS, fulfills a gap in the existing apparatus. The “roller on circular rail” design was chosen to fit the tribological behavior of wheel-rail contact, and replicate RCF defects. The production of a test bench required to relate and differentiate the measured data to the phenomena corresponding to the operating from the phenomena corresponding to wheel-rail contact. The bench was characterized with dynamic and cinematic analysis. The design of the sample was improved. The tribological behavior of the bench was optimized with the preparation of the initial surface of the samples and the production of a tribological “fuse”. This layer delays the speed accommodation by wear and benefit the shear of the first bodies and the formation a Tribological Transformation of Surface (TTS), as the White Etching Layer. The two different fuse layer created (Run-in and oxidized), induced a significant wear reduction. The tribological and metallurgical analysis of the surfaces and cuts of the sample, enabled to the explanation of the evolution of the microstructure of the rail close to the surface, submitted to various mechanical solicitations. The transformation of this microstructure led to the formation of white etching layer mechanically formed
APA, Harvard, Vancouver, ISO, and other styles
33

Figueiredo, Marcus Tadeu Tanuri de. "Análise dos procedimentos e critérios de implantação de feixes de raios X de referência ISO 4037 em baixas energias." CNEN - Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte, 2012. http://www.bdtd.cdtn.br//tde_busca/arquivo.php?codArquivo=260.

Full text
Abstract:
De acordo com os princípios da proteção radiológica, as práticas que envolvem radiações ionizantes devem ser planejadas e executadas de modo que os valores de doses individuais, o número de pessoas expostas e a probabilidade de exposições acidentais sejam tão baixos quanto razoavelmente exequíveis. Para tanto, faz-se necessário que na execução da dosimetria das radiações sejam utilizados medidores confiáveis de grandezas dosimétricas. Esta confiabilidade depende não só da calibração do medidor, mas também do seu desempenho em determinadas condições de teste. A International Standardization Organization (ISO), com o objetivo de promover a padronização e a coerência metrológica internacional, estabeleceu conjuntos de feixes de raios X de referência para calibração e testes de dosímetros, cuja implantação nos laboratórios de metrologia deve atender a requisitos técnicos específicos. Em baixas energias existem especificidades que precisam ser consideradas tanto na implantação dos feixes de referência quanto na sua utilização em calibração e testes. O presente trabalho faz uma análise dos procedimentos e critérios de implantação das radiações de referência ISO 4037, em baixas energias. Foram realizados experimentos que permitiram cálculos de parâmetros de caracterização dos feixes de referência do Laboratório de Calibração de Dosímetros do Centro de Desenvolvimento da Tecnologia Nuclear (LCD/CDTN). Alternativas às metodologias usuais de determinação da camada semirredutora foram estudadas. Espectros de feixes de referência foram simulados por meio de softwares e comparados com espectros medidos experimentalmente. Condições climáticas distintas foram reproduzidas em laboratório para análise dos seus efeitos sobre os parâmetros dos feixes. Incertezas em relação às medidas de parâmetros de implantação foram avaliadas. Os feixes de baixa energia, de acordo com os critérios da norma ISO 4037, foram considerados implantados, permitindo a revisão dos valores dos coeficientes de conversão de kerma no ar para grandezas operacionais de proteção radiológica.
According to the radiological protection principles, practices involving ionizing radiation must be planned and carried out under the guarantee that the values of individual doses, the number of people exposed to radiation and the probability of accidental exposures are as low as reasonably achievable. Therefore, radiation dosimetry is required to be done with reliable instruments designed for measuring dosimetric quantities. The reliability of the dosimetry depends on both the calibration of the dosimeter and its proper performance under certain test conditions. The International Standardization Organization (ISO), in order to promote international standardization and metrological coherency, established sets of reference X-ray beams for dosimeter calibration and typing-test; they are expected to be implemented in metrology laboratories in compliance with specific technical requirements. At low energies there are specific requirements that need to be considered in both the implementation of the reference beams and their use in calibration and testing. The present study is an analysis of the procedures and criteria for ISO 4037 reference radiation implementation, at low energies. In the Dosimeter Calibration Laboratory of the Development Center of Nuclear Technology (LCD / CDTN), experiments were performed for determining the X-ray reference radiation parameters. Alternatives to the usual methods for half-value layer determination were studied. Spectra of reference beams were simulated with software and compared with experimental measurements. Different climatic conditions were reproduced in the Laboratory for analysis of its influence on the determination of the beam parameters. Uncertainties in the measurements of studied parameters were evaluated. According to the ISO 4037 criteria, the low energy X-ray beams were considered to be implemented; they allowed the determination of the conversion coefficients from air kerma to the operational radiation protection quantities.
APA, Harvard, Vancouver, ISO, and other styles
34

Torres, Guilherme Vaz. "Nova abordagem para o processamento e análise de imagens topográficas da córnea humana." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-03032008-090325/.

Full text
Abstract:
O presente trabalho trata-se do desenvolvimento de um programa para de análise de imagens de topografia corneana de sistemas comerciais, para ser implementado no topógrafo corneano para Lâmpada de Fenda, em desenvolvimento no Laboratório de Instrumentação Oftálmica - EESC/USP e no Laboratório de Física Oftálmica - FMRP/USP. O programa foi desenvolvido em C++, utilizando a plataforma Windows, e fornece mapas axiais de topografia corneana. O programa foi testado em esferas de calibração e em olhos humanos, apresentando um fator de correlação de 0,9998 para as medidas em esferas e um erro inerente estimado em 3%. Os mapas de topografias axiais em olhos humanos foram comparados com os mapas gerados por sistemas comerciais e o padrão visual de forma e relevo estão em concordância.
This work is about a software for the analisys of corneal topography images provided by commercial available systems to be implemented in a corneal topographer for slit lamps under evelopment at Laboratório de Instrumentação Oftálmica . EESC/USP e no Laboratório de Física Oftálmica . FRMP/USP. The software was developed in Borland C++ Builder for Windows and provides the corneal topography axial maps. The software has been tested in calibration spheres and in human eyes, presenting a correlation factor of 0,9998 for the measurements performed in the spheres and an inherent error of 3%. The axial topographic maps form the exams performe in human eyes have been compared to the axial maps provided by the commercial available system and the visual pattern as well as the relief are in accordance.
APA, Harvard, Vancouver, ISO, and other styles
35

Karlsson, Oskar. "Lidar-based SLAM : Investigation of environmental changes and use of road-edges for improved positioning." Thesis, Linköpings universitet, Reglerteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-165288.

Full text
Abstract:
The ability to position yourself and map the surroundings is an important aspect for both civilian and military applications. Global navigation satellite systems are very popular and are widely used for positioning. This kind of system is however quite easy to disturb and therefore lacks robustness. The introduction of autonomous vehicles has accelerated the development of local positioning systems. This thesis work is done in collaboration with FOI in Linköping, using a positioning system with LIDAR and IMU sensors in a EKF-SLAM system using the GTSAM framework. The goal was to evaluate the system in different conditions and also investigate the possibility of using the road surface for positioning. Data available at FOI was used for evaluation. These data sets have a known sensor setup and matches the intended hardware. The data sets used have been gathered on three different occasions in a residential area, a country road and a forest road in sunny spring weather on two occasions and one occasion in winter conditions. To evaluate the performance several different measures were used, common ones such as looking at positioning error and RMSE, but also the number of found landmarks, the estimated distance between landmarks and the drift of the vehicle. All results pointed towards the forest road providing the best positioning, the country road the worst and the residential area in between. When comparing different weather conditions the data set from winter conditions performed the best. The difference between the two spring data sets was quite different which indicates that there may be other factors at play than just weather. A road edge detector was implemented to improve mapping and positioning. Vectors, denoted road vectors, with position and orientation were adapted to the edge points and the change between these road vectors were used in the system using GTSAM in areas with few landmarks. The clearest improvements to the drift in the vehicle direction was in the longer country area where the error was lowered with 6.4 % with increase in the error sideways and in orientation as side effects. The implemented method has a significant impact on the computational cost of the system as well as requiring precise adjustment of uncertainty to have a noticeable improvement and not worsen the overall results.
APA, Harvard, Vancouver, ISO, and other styles
36

Sadoudi, Laïd. "Étude et développement d'une plateforme de communication pour les réseaux de capteurs acoustiques sans fil : application au contrôle-santé des rails par corrélation du bruit ambiant." Thesis, Valenciennes, 2016. http://www.theses.fr/2016VALE0018/document.

Full text
Abstract:
Le Contrôle-Santé Intégré (CSI) réduit les besoins d’inspections humaines grâce à une surveillance automatisée, réduit les coûts de maintenance grâce à la détection précoce des anomalies avant qu’elles ne dégénèrent et améliore la sécurité ainsi que la fiabilité des services. L’objectif de cette thèse est de concevoir une plateforme de communication sans fil pour le CSI des structures ferroviaires. Le principe de contrôle repose sur la reconstruction des réponses impulsionnelles (fonctions de Green) par corrélation de bruit aléatoire se propageant dans le milieu. Durant ces travaux, nous avons éprouvé expérimentalement la relation entre les réponses actives expérimentales et une version post-traitée des fonctions de corrélation de bruit dans un contexte ferroviaire. Ainsi, nous avons démontré l’applicabilité des fonctions de corrélation pour la détection d’un défaut local sur un rail. Ensuite, nous avons réalisé une étude expérimentale comparative sur la caractérisation d’une transmission ZigBee en termes d’atténuation et de portée dans plusieurs environnements. Dans l’environnement ferroviaire sous test, nous avons démontré l’adéquation avec la portée d’une transmission ZigBee mono-saut (dans un rayon de 76m). Une solution de synchronisation des capteurs lors du prélèvement du signal basée sur la norme IEEE 802.15.4 a été proposée et validée par une campagne de mesures. Il a été démontré que cette approche offre une précision de l’ordre de quelques centaines de nanosecondes. Un prototype-plateforme de communication sans fil basé sur la technologie ZigBee/IEEE 802.15.4 a été mis en place et déployé sur un échantillon de rail. Cette solution a permis de valider les performances de cette plateforme, une fois les données récoltées par les transducteurs, ces informations sont transmises par un lien ZigBee vers une station de base où des algorithmes de détection leurs sont appliqués
Structural Health Monitoring (SHM) reduces human inspection requirements through automated monitoring, reduces maintenance costs by early detection of defects before they escalate, and improves safety and reliability of services. The work presented in this thesis aims to design a wireless communication platform for railway structures health monitoring. The control principle is based on the reconstruction of impulse responses (Green’s functions) by correlation of random noise propagated in the medium. In this work, direct comparison between an active emission-reception response and the estimated noise correlation function has confirmed the validity of the equivalence relation between them. Thus, we have demonstrated the applicability of the correlation functions for local defect detection in a rail. Then, we conducted an experimental study on the characterization of a ZigBee transmission in terms of path loss and communication range in multiple environments. In the railway environment under test, we showed the adequacy with the range of a ZigBee single-hop transmission (within a radius of 76m). Furthermore, a flexible solution for sensors synchronization during the sampling process, based on IEEE 802.15.4 standard was proposed and validated by a measurement campaign. It has been demonstrated that this approach provides a precision of a few hundred nanoseconds. A wireless communication-platform prototype based on the ZigBee/IEEE 802.15.4 technology has been implemented and deployed on a rail sample. This solution enabled the validation of the platform performances, once the data collected by the transducers, the information is transmitted by a ZigBee link to a base station where detection algorithms are applied
APA, Harvard, Vancouver, ISO, and other styles
37

Rachedi, Nedjemi Djamel Eddine. "Modélisation et surveillance de systèmes Homme-Machine : application à la conduite ferroviaire." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0009.

Full text
Abstract:
Ce travail de thèse a pour contexte la surveillance des systèmes homme-machine, où l'opérateur est le conducteur d'un système de transport ferroviaire. Notre objectif est d'améliorer la sécurité du système en prévenant et en évitant les facteurs pouvant augmenter le risque d'une erreur humaine. Deux verrous majeurs sont identifiés : l'aspect caractérisation, ou comment déterminer les phases indicatives et discernables de l'activité de conduite et l'aspect représentation, ou comment décrire et codifier les actions de conduite de l'opérateur et leurs répercussions sur le système ferroviaire dans un formalisme mathématique permettant une analyse sans équivoque. Pour solutionner ces verrous, nous proposons en premier lieu un modèle comportemental de l'opérateur humain permettant de représenter son comportement de contrôle en temps continu. Afin de tenir compte des différences inter- et intra-individuelles des opérateurs humains, ainsi des changements de situations, nous proposons une transformation du modèle comportemental initialement présenté, dans un nouveau espace de représentation. Cette transformation est basée sur la théorie des chaines cachées de Markov, et sur l'adaptation d'une technique particulière de reconnaissance de formes. Par la suite, nous définissons une modélisation comportementale en temps discret de l'opérateur humain, permettant en même temps de représenter ses actions et de tenir compte des erreurs et des évènements inattendus dans l'environnement de travail. Cette modélisation est inspirée des modèles cognitifs d’opérateur. Les deux aspects permettent d'interpréter les observables par rapport à des situations de référence. Afin de caractériser l'état global de l'opérateur humain, différentes informations sont prises en considération ; ces informations sont hétérogènes et entachées d’incertitudes de mesure, nécessitant une procédure de fusion de données robuste qui est effectuée à l'aide d'un réseau Bayésien. Au final, les méthodologies de modélisation et de fusion proposées sont exploitées pour la conception d'un système de vigilance fiable et non-intrusif. Ce système permet d'interpréter les comportements de conduite et de détecter les états à risque du conducteur (ex. l'hypovigilance). L'étude théorique a été testée en simulation pour vérifier sa validité. Puis, une étude de faisabilité a été menée sur des données expérimentales obtenues lors des expériences sur la plate-forme de conduite ferroviaire COR&GEST du laboratoire LAMIH. Ces résultats ont permis de planifier et de mettre en place les expérimentations à mener sur le futur simulateur de conduite multimodal "PSCHITT-PMR"
The scope of the thesis is the monitoring of human-machine systems, where the operator is the driver of rail-based transportation system. Our objective is to improve the security of the system preventing and avoiding factors that increase the risk of a human error. Two major problems are identified: characterization, or how to determine indicative and discernible phases of driver's activity and representation, or how to describe and codify driver's actions and its repercussions on the rail system in a mathematical formalism that will allow unequivocal analysis. In order to bring a solution to those problems, we propose, first-of-all, a behavioral model of the human operator representing his control behavior in continuous-time. To consider inter- and intra-individual differences of human operators and situation changes, we propose a transformation of the latter behavioral model in a new space of representation. This transformation is based on the theory of Hidden Markov Models, and on an adaptation of a special pattern recognition technique. Then, we propose a discrete-time behavioral modeling of the human operator, which represents his actions and takes account of errors and unexpected events in work environment. This model is inspired by cognitive models of human operators. These two aspects allow us to interpret observables with respect to reference situations in order to characterize the overall human operator state. Different information sources are considered; as a result the data are heterogeneous and subject to measuring uncertainties, needing a robust data fusion approach that is performed using a Bayesian Network. Finally, the proposed modeling and fusion methodologies are used to design a reliable and unintrusive vigilance system. This system can interpret driving behaviors and to detect driver’s risky states in order to prevent drowsiness. The theoretical study was tested in simulation to check the validity. Then, a feasibility study was conducted using data obtained during experiments on the LAMIH laboratory railroad platform “COR&GEST”. These results allowed us to plan and implement experiments to be conducted on the future multimodal driving simulator “PSCHITT-PMR”
APA, Harvard, Vancouver, ISO, and other styles
38

Eriksson, Niklas, and Patrik Lifvendahl. "Utbildningssimulator av funktioner i spårfordon : Hårdvarusimulator med felsökning på dörrsystem." Thesis, KTH, Data- och elektroteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168951.

Full text
Abstract:
I denna rapport beskrivs en utvecklad utbildningssimulator över spårfordon och dess del- komponenter på järnvägen. Simulatorn är en hårdvarubaserad prototyp över ett dörrsystem på spårfordon. Prototypen ska användas av systemspecialister och tekniker inom järnvägs- branschen. Simulatorn ger användare en teknisk demonstration av hur komponenter funge- rar i ett dörrsystem. Prototypen innehåller motor, brytare, reläer och givare. Komponenterna används för att illustrerar funktioner i ett dörrsystem på ett spårfordon. Utbildningssimula- torn kontrolleras med en styrenhet och genom tryckknappar för manuell styrning. För de- monstration av säkerheten vid av och ombordstigning används en optisk givare som symbo- liserar hinderdetektering. Utbildningssimulatorn har två vanliga fel inbyggda: kabelfel och jordfel. En instruktions- manual bestående av ett kretsschema används för felsökning. Kretsschemat över dörrsyste- met används för hitta felen och åtgärda dem. I felanalysen ingår de faktorer som är orsaken till att de vanligaste felen inträffar på ett spårfordon. Dörrsystem tar emot diagnostiska ko- der från en dörrdator som styr prioriteringen på vilka åtgärder som ska göras.
This report is a description of a developed educational simulator over rail vehicles and its components. The simulator is a hardware-based prototype over a door system on rail vehi- cles. System specialists and technicians will use the prototype. The Simulator should give the user a technical demonstration on how components work in a door system. The proto- type consists of motor, switch, relay and sensor. The components are used for illustration of the functions in a door system on a rail vehicle. The educational simulator is controlled with a control unit and with pushbuttons for manual control. For demonstration of the boarding security an optical sensor is used as symbolize for the obstacle detection. The educational simulation has two embedded common faults: cable fault and ground fault. The instruction manual consists of a circuit diagram and is used for troubleshooting. The circuit diagram over the door system is used to find the faults and to correct them. The fault analysis includes the factors, which is the reason for the most common faults to occur in a rail vehicle. Door system receives diagnostic code from a door computer that control priori- tizing for arrangements that will be made.
APA, Harvard, Vancouver, ISO, and other styles
39

NOTARANGELO, NICLA MARIA. "A Deep Learning approach for monitoring severe rainfall in urban catchments using consumer cameras. Models development and deployment on a case study in Matera (Italy) Un approccio basato sul Deep Learning per monitorare le piogge intense nei bacini urbani utilizzando fotocamere generiche. Sviluppo e implementazione di modelli su un caso di studio a Matera (Italia)." Doctoral thesis, Università degli studi della Basilicata, 2021. http://hdl.handle.net/11563/147016.

Full text
Abstract:
In the last 50 years, flooding has figured as the most frequent and widespread natural disaster globally. Extreme precipitation events stemming from climate change could alter the hydro-geological regime resulting in increased flood risk. Near real-time precipitation monitoring at local scale is essential for flood risk mitigation in urban and suburban areas, due to their high vulnerability. Presently, most of the rainfall data is obtained from ground‐based measurements or remote sensing that provide limited information in terms of temporal or spatial resolution. Other problems may be due to the high costs. Furthermore, rain gauges are unevenly spread and usually placed away from urban centers. In this context, a big potential is represented by the use of innovative techniques to develop low-cost monitoring systems. Despite the diversity of purposes, methods and epistemological fields, the literature on the visual effects of the rain supports the idea of camera-based rain sensors but tends to be device-specific. The present thesis aims to investigate the use of easily available photographing devices as rain detectors-gauges to develop a dense network of low-cost rainfall sensors to support the traditional methods with an expeditious solution embeddable into smart devices. As opposed to existing works, the study focuses on maximizing the number of image sources (like smartphones, general-purpose surveillance cameras, dashboard cameras, webcams, digital cameras, etc.). This encompasses cases where it is not possible to adjust the camera parameters or obtain shots in timelines or videos. Using a Deep Learning approach, the rainfall characterization can be achieved through the analysis of the perceptual aspects that determine whether and how a photograph represents a rainy condition. The first scenario of interest for the supervised learning was a binary classification; the binary output (presence or absence of rain) allows the detection of the presence of precipitation: the cameras act as rain detectors. Similarly, the second scenario of interest was a multi-class classification; the multi-class output described a range of quasi-instantaneous rainfall intensity: the cameras act as rain estimators. Using Transfer Learning with Convolutional Neural Networks, the developed models were compiled, trained, validated, and tested. The preparation of the classifiers included the preparation of a suitable dataset encompassing unconstrained verisimilar settings: open data, several data owned by National Research Institute for Earth Science and Disaster Prevention - NIED (dashboard cameras in Japan coupled with high precision multi-parameter radar data), and experimental activities conducted in the NIED Large Scale Rainfall Simulator. The outcomes were applied to a real-world scenario, with the experimentation through a pre-existent surveillance camera using 5G connectivity provided by Telecom Italia S.p.A. in the city of Matera (Italy). Analysis unfolded on several levels providing an overview of generic issues relating to the urban flood risk paradigm and specific territorial questions inherent with the case study. These include the context aspects, the important role of rainfall from driving the millennial urban evolution to determining present criticality, and components of a Web prototype for flood risk communication at local scale. The results and the model deployment raise the possibility that low‐cost technologies and local capacities can help to retrieve rainfall information for flood early warning systems based on the identification of a significant meteorological state. The binary model reached accuracy and F1 score values of 85.28% and 0.86 for the test, and 83.35% and 0.82 for the deployment. The multi-class model reached test average accuracy and macro-averaged F1 score values of 77.71% and 0.73 for the 6-way classifier, and 78.05% and 0.81 for the 5-class. The best performances were obtained in heavy rainfall and no-rain conditions, whereas the mispredictions are related to less severe precipitation. The proposed method has limited operational requirements, can be easily and quickly implemented in real use cases, exploiting pre-existent devices with a parsimonious use of economic and computational resources. The classification can be performed on single photographs taken in disparate conditions by commonly used acquisition devices, i.e. by static or moving cameras without adjusted parameters. This approach is especially useful in urban areas where measurement methods such as rain gauges encounter installation difficulties or operational limitations or in contexts where there is no availability of remote sensing data. The system does not suit scenes that are also misleading for human visual perception. The approximations inherent in the output are acknowledged. Additional data may be gathered to address gaps that are apparent and improve the accuracy of the precipitation intensity prediction. Future research might explore the integration with further experiments and crowdsourced data, to promote communication, participation, and dialogue among stakeholders and to increase public awareness, emergency response, and civic engagement through the smart community idea.
Negli ultimi 50 anni, le alluvioni si sono confermate come il disastro naturale più frequente e diffuso a livello globale. Tra gli impatti degli eventi meteorologici estremi, conseguenti ai cambiamenti climatici, rientrano le alterazioni del regime idrogeologico con conseguente incremento del rischio alluvionale. Il monitoraggio delle precipitazioni in tempo quasi reale su scala locale è essenziale per la mitigazione del rischio di alluvione in ambito urbano e periurbano, aree connotate da un'elevata vulnerabilità. Attualmente, la maggior parte dei dati sulle precipitazioni è ottenuta da misurazioni a terra o telerilevamento che forniscono informazioni limitate in termini di risoluzione temporale o spaziale. Ulteriori problemi possono derivare dagli elevati costi. Inoltre i pluviometri sono distribuiti in modo non uniforme e spesso posizionati piuttosto lontano dai centri urbani, comportando criticità e discontinuità nel monitoraggio. In questo contesto, un grande potenziale è rappresentato dall'utilizzo di tecniche innovative per sviluppare sistemi inediti di monitoraggio a basso costo. Nonostante la diversità di scopi, metodi e campi epistemologici, la letteratura sugli effetti visivi della pioggia supporta l'idea di sensori di pioggia basati su telecamera, ma tende ad essere specifica per dispositivo scelto. La presente tesi punta a indagare l'uso di dispositivi fotografici facilmente reperibili come rilevatori-misuratori di pioggia, per sviluppare una fitta rete di sensori a basso costo a supporto dei metodi tradizionali con una soluzione rapida incorporabile in dispositivi intelligenti. A differenza dei lavori esistenti, lo studio si concentra sulla massimizzazione del numero di fonti di immagini (smartphone, telecamere di sorveglianza generiche, telecamere da cruscotto, webcam, telecamere digitali, ecc.). Ciò comprende casi in cui non sia possibile regolare i parametri fotografici o ottenere scatti in timeline o video. Utilizzando un approccio di Deep Learning, la caratterizzazione delle precipitazioni può essere ottenuta attraverso l'analisi degli aspetti percettivi che determinano se e come una fotografia rappresenti una condizione di pioggia. Il primo scenario di interesse per l'apprendimento supervisionato è una classificazione binaria; l'output binario (presenza o assenza di pioggia) consente la rilevazione della presenza di precipitazione: gli apparecchi fotografici fungono da rivelatori di pioggia. Analogamente, il secondo scenario di interesse è una classificazione multi-classe; l'output multi-classe descrive un intervallo di intensità delle precipitazioni quasi istantanee: le fotocamere fungono da misuratori di pioggia. Utilizzando tecniche di Transfer Learning con reti neurali convoluzionali, i modelli sviluppati sono stati compilati, addestrati, convalidati e testati. La preparazione dei classificatori ha incluso la preparazione di un set di dati adeguato con impostazioni verosimili e non vincolate: dati aperti, diversi dati di proprietà del National Research Institute for Earth Science and Disaster Prevention - NIED (telecamere dashboard in Giappone accoppiate con dati radar multiparametrici ad alta precisione) e attività sperimentali condotte nel simulatore di pioggia su larga scala del NIED. I risultati sono stati applicati a uno scenario reale, con la sperimentazione attraverso una telecamera di sorveglianza preesistente che utilizza la connettività 5G fornita da Telecom Italia S.p.A. nella città di Matera (Italia). L'analisi si è svolta su più livelli, fornendo una panoramica sulle questioni relative al paradigma del rischio di alluvione in ambito urbano e questioni territoriali specifiche inerenti al caso di studio. Queste ultime includono diversi aspetti del contesto, l'importante ruolo delle piogge dal guidare l'evoluzione millenaria della morfologia urbana alla determinazione delle criticità attuali, oltre ad alcune componenti di un prototipo Web per la comunicazione del rischio alluvionale su scala locale. I risultati ottenuti e l'implementazione del modello corroborano la possibilità che le tecnologie a basso costo e le capacità locali possano aiutare a caratterizzare la forzante pluviometrica a supporto dei sistemi di allerta precoce basati sull'identificazione di uno stato meteorologico significativo. Il modello binario ha raggiunto un'accuratezza e un F1-score di 85,28% e 0,86 per il set di test e di 83,35% e 0,82 per l'implementazione nel caso di studio. Il modello multi-classe ha raggiunto un'accuratezza media e F1-score medio (macro-average) di 77,71% e 0,73 per il classificatore a 6 vie e 78,05% e 0,81 per quello a 5 classi. Le prestazioni migliori sono state ottenute nelle classi relative a forti precipitazioni e assenza di pioggia, mentre le previsioni errate sono legate a precipitazioni meno estreme. Il metodo proposto richiede requisiti operativi limitati, può essere implementato facilmente e rapidamente in casi d'uso reali, sfruttando dispositivi preesistenti con un uso parsimonioso di risorse economiche e computazionali. La classificazione può essere eseguita su singole fotografie scattate in condizioni disparate da dispositivi di acquisizione di uso comune, ovvero da telecamere statiche o in movimento senza regolazione dei parametri. Questo approccio potrebbe essere particolarmente utile nelle aree urbane in cui i metodi di misurazione come i pluviometri incontrano difficoltà di installazione o limitazioni operative o in contesti in cui non sono disponibili dati di telerilevamento o radar. Il sistema non si adatta a scene che sono fuorvianti anche per la percezione visiva umana. I limiti attuali risiedono nelle approssimazioni intrinseche negli output. Per colmare le lacune evidenti e migliorare l'accuratezza della previsione dell'intensità di precipitazione, sarebbe possibile un'ulteriore raccolta di dati. Sviluppi futuri potrebbero riguardare l'integrazione con ulteriori esperimenti in campo e dati da crowdsourcing, per promuovere comunicazione, partecipazione e dialogo aumentando la resilienza attraverso consapevolezza pubblica e impegno civico in una concezione di comunità smart.
APA, Harvard, Vancouver, ISO, and other styles
40

Chen, Guan-jhih, and 陳冠志. "Physics-based Rain Removal for Moving Object Detection." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/71102568344561479948.

Full text
Abstract:
碩士
國立中央大學
資訊工程研究所
98
Physical noises, such as rain, frequently affect the detection performance of moving-objects when they present in a film or a monitoring system. The elimination of physical noises is thus a prerequisite to uplift the detection accuracy. There are different kinds of noises needed to be eliminated under different weather conditions. The elimination of rain drops, due to the random spatial distribution and fast motion in short time, is hence admitted as a challenging problem. In this thesis, we improve the detection method of rain drops and construct the estimation on the intensity of background. Extensive studies were conducted in analyzing these algorithms. However, not all of the detected pixels contain real rain drops if merely find them based on the property of intensity change. To remove the false alarm, we use three effective features in our work and construct the environmental parameters of features by MLPNN (Multilayer Perceptron Neural Network) training. One of the features is the changed value of color from Cb and Cr. The probability of a pixel containing moving objects is higher if the changed value is high. The second feature is the information obtained by the sobel edge detector. Generally, the lower value in edge will exist in the rain area. The last feature is the saturation value of a pixel. A range of saturation values exists in the rain area. The result of classified method can be used for making decisions on false alarm, or we can use it on the algorithm in constructing the color-correlation to map more false alarms. The color-correlation is very useful for removing the false alarm in moving objects. The proposed method is implemented on object detection to find real foreground. We analyze the detecting accuracy with and without the rain removal system in the normal illumination cameras or films. The results show that the proposed system is indeed helpful on moving-object detection in the rainy weather. It really reduces the false alarm although the accuracy is not raised with the rain removal system.
APA, Harvard, Vancouver, ISO, and other styles
41

Warburton, Michele Lynn. "Detection of changes in temperature and streamflow parameters over Southern Africa." Thesis, 2005. http://hdl.handle.net/10413/3514.

Full text
Abstract:
It has become accepted that long-term global mean temperatures have increased over the twentieth century. However, whether or not climate change can be detected at a local or regional scale is still questionable. The numerous new record highs and lows of temperatures recorded over South Africa for 2003, 2004 and 2005 provide reason to examine whether changes can already be detected in southern Africa's temperature record and modelled hydrological responses. As a preface to a temperature detection study, a literature reVIew on temperature detection studies, methods used and data problems encountered, was undertaken. Simple statistics, linear regression and the Mann-Kendall non-parametric test were the methods reviewed for detecting change. Southern Africa's temperature record was thereafter examined for changes, and the Mann-Kendall non-parametric test was applied to time series of annual means of minimum and maximum temperature, summer means of maximum temperature and winter means of minimum temperature. Furthermore, changes in the upper and lower ends of the temperature distribution were examined. The Mann-Kendall test was applied to numbers of days and numbers of 3 consecutive days abovelbelow thresholds of 10th and 90th percentiles of minimum and maximum temperatures, as well as abovelbelow threshold values of minimum (i.e. 0°) and maximum (i.e. 40°C) temperatures. A second analysis, using the split sample technique for the periods 1950 - 1970 vs 1980 - 2000, was performed for annual means of daily maximum and minimum temperatures, summer means of daily maximum temperatures, winter means of daily minimum temperatures and coefficients of variability of daily maximum and minimum temperatures. Two clear clusters of warming emerged from almost every analysis, viz. a cluster of stations in the Western Cape and a cluster of stations around the midlands ofKwaZulu-Natal, along with a band of stations along the KwaZulu-Natal coast. Another fmding was a less severe frost season over the Free State and Northern Cape. While certain changes are, therefore, evident in temperature parameters, the changes are not uniform across southern Africa. Precipitation and evaporation are the primary drivers of the hydrological cycle, with temperature an important factor in the evaporation process. Thus, with changes in various temperature parameters having been identified over many parts of southern Africa, the question arose whether any changes were evident as yet in hydrological responses. The ACRU model was used to generate daily streamflow values and associated hydrological responses from a baseline land cover, thus eliminating all possible human influences on the catchment and channel. A split-sample analysis of the simulated hydrological responses for the 1950 - 1969 vs 1980 - 1999 periods was undertaken. Trends over time in simulated streamflows were examined for medians, dry and wet years, as well as the range between wet and dry years. The seasonality and concentration of streamflows between the periods 1950 - 1969 and 1980 - 1999 were examined to determine if changes could be identified. Some trends found were marked over large parts of Primary Catchments, and certainly require consideration in future water resources planning. With strong changes over time in simulated hydrological responses already evident in certain Primary Catchments of South Africa using daily rainfall input data from 1950 1999, it, therefore, became necessary to examine the rainfall regimes of the Quaternary Catchments' "driver" rainfall station data in order to determine if these hydrological response changes were supported by changes in rainfall patterns over time. A splitsample analysis was, therefore, performed on the rainfall input of each Quaternary Catchment. Not only were medians considered, but the higher and lower ends of the rainfall distributions were also analysed, as were the number of rainfall events above pre-defined daily thresholds. The changes evident over time in rainfall patterns over southern Africa were found to vary from relatively unsubstantial increases or decreases to significant increase and decreases. However, the changes in rainfall corresponded with the changes noted in simulated streamflow. From the analyses conducted in this study, it has become clear that South Africa's temperature and rainfall, as well as hydrological responses, have changed over the recent past, particularly in certain identifiable hotspots, viz. the Western Cape and KwaZulu-Natal where significant increases in temperature variables and changes in rainfall patterns were detected. These detected changes in climate need to be considered in future water resources planning.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
APA, Harvard, Vancouver, ISO, and other styles
42

Chiang, Lee-Chen, and 姜禮城. "Ⅰ. Determination of the Chemical Oxgen Demand. Ⅱ. Determination the Efficiency of Detection Chemical Components and Physical Components for the Rainwater in Jong-Lih Area by Acid rain Automatic Monitoring." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/85025288337277938831.

Full text
Abstract:
碩士
淡江大學
水資源及環境工程學系
87
Ⅰ. Determination of the Chemical Oxgen Demand in the Wastewater Using Microwave Energy — The Comparison Between the Closed Method And the Open Focus Reflux Method. In environmental analytic chemistry microwave-assisted methods for sample preparation have been increased rapidly in recent years .The closed vessel method and open focus reflux method were used for the determination of chemical oxygen demand (COD) in the digestion-oxidation step which was by using microwave energy. The goals of this study are to develop the mercury-free microwave assisted,digestion for COD determination and to compare between the open focus microwave and the closed vessel sample preparation methods. The optimized conditions for the closed vessel method are: sample, 5ml; sulfuric acid(0.55﹪Ag+), 7ml;0.0705M silver nitrate,1ml; 0.0417M potassium dichromate, 2ml; power(using domestic microwave oven): 512 W, reaction time: 5mins. The optimized conditions for the open focus reflux method are: sample, 5ml; sulfuric acid(0.55﹪Ag+), 7ml;0.0705M silver nitrate,1ml; 0.0417M potassium dichromate, 2ml; power(using open focus microwave oven): 300W, reaction time: 5mins. The average recovery of the closed vessel method for quality control samples were 98.3﹪and S. D. 1.8﹪.The average recovery of the open focus reflux method for quality control samples was 98.7﹪and S. D. 1.2﹪The ratio between COD values, determined by the open focus method and the closed vessel methods is 0.9360. The results show that both methods are comparable. Ⅱ. Determination the Efficiency of Detection Chemical and Physical Components for the Rainwater in Chung-Li Area by Acid rain Automatic Monitoring. The aims of this study are to characterize the rainfalls by physical and chemical parameter Chung-Li area and to compare the data from acid rain monitor with the results obtained in the laboratory. The physical and chemical parameters included temperature, rainfalls intensity, electrical conductivity, turbidity, pH value cation concentration (Na+,K+,NH4+,Ca2+,Mg2+) and anion concentration( Cl-,NO3-,SO42-).The results showed that the pH values, temperature, rainfalls intensity and electrical conductivity were very good as compared with that from the lab. However, the sulfate and nitrate by acid rain monitor, s spectrophotometer were poor probably because of bubbles and contamination in the line . Ion chromatography with conductivity detector has been used to determine cations and anions separately. The nitric acid solution(0.5mM) was used with cation-exchange column (MCI GEL SCK01) having low cation exchange capacities. The dilute 3mM Vanillin Acid and 2.8mM N-Methydiethanolamine(pH6.2) have been the main eluent species used for anions. The result shows the range of ratios (SO42 /NO3-)was 1~5 and the range of pH values were 4~7 for the rainwater in Chung-Li area.
APA, Harvard, Vancouver, ISO, and other styles
43

Li, Yi-Chun, and 李亦鈞. "Road Detection System for Rainy Days." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/36054550849002039688.

Full text
Abstract:
碩士
國立臺灣師範大學
資訊工程學系
103
The last two decades, for the driving safety, in-car video camera technology for estimating road shape ahead of a vehicle for the purpose of driver assistance has been developed and implemented. A road detection technology can provide the road shape, area and lane markings, which can share with other advance driver assistance systems (ADAS). Although road detection is a mature technology, there are a few studies on road detection for rainy days. Recent studies use mostly road boundary to detect road area. If road boundary is not clear, it would fail to detect the correct road area. To effectively handle road detection on rainy days, the proposed method comprises three modules: 1) log chromaticity space, 2) sensor sharpening matrix transform, and 3) watershed segmentation. To speed up the road detection processing, the region-of-interest (ROI) is used to choose the candidate searching range for extract road features. The system then process the log chromaticity space method and sensor sharpening matrix transform method. Finally, the watershed segmentation method as an error correction mechanism is applied. Experimental results on real road scenes such as light rain, moderate rain, and heavy rain show that if road scenes is bright enough and vehicles have vivid color, the proposed method has substantiated the effectiveness of accuracy results.
APA, Harvard, Vancouver, ISO, and other styles
44

Hsieh, Chang-Ju, and 謝昌儒. "Real Time Traffic Sign Detection and Recognition in Rainy Weather." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/88404661299372975366.

Full text
Abstract:
碩士
國立雲林科技大學
資訊工程系碩士班
100
In this paper, a new real time traffic sign detection and recognition system has been proposed. This system will focus on rainy weather and process the affects of the rainy weather on the prohibitory (red) and warning (blue) of traffic signs used in Taiwan by detection and recognition systems. First, the detection method is formed by combing RGB and HSI color space which apply well to detect traffic signs in rainy weather. The template matching was employed to classify the shape of candidates and the support vector machine was used to recognize the content of the traffic sign candidates. Our results show that the average detection rate is 90.78% and the average recognition rate is 89.13%.
APA, Harvard, Vancouver, ISO, and other styles
45

Pereira, André Filipe Rainho. "Rail Corrugation: A Software Tool for Detection and Analysis Using Wavelets." Master's thesis, 2018. http://hdl.handle.net/10362/61576.

Full text
Abstract:
Corrugation is an oscillatory wear of the rail and it is a consequence of the interaction between wheel and rail [1]. Rail corrugation usually appears in curves, but it may also arise in linear tracks. It usually appears in curves because of the friction between the rail and wheel due to curving [2]. The main objective of this master thesis is to develop new methods that can detect if there is corrugation in the rail and quantify it according to the frequency and amplitude of the signal. A program has been already developed at FCT-UNL enabling the detection of rail corrugation, RailScan V2.1. However, this application is outdated, so the aim is to update it and make it more efficient, building a brand-new RailScan V3.0. The implementation of the function Corrugram, a patent developed in FCT-UNL, was a huge evolution in RailScan. Corrugram is a new way to represent where and if corrugation is present in the rail. Another implementation was the norm EN 13231-3:2012, another method to analyze if rail corrugation is present. This norm was incorporated within RailScan V3.0, and it ensured compliance against the best international practice among rail corporations [3]. The remaining part of this thesis was to create a database with robust data, allowing the validation of both RailScan and Corrugram as powerful tools to quantify rail corrugation. The results proved that RailScan is a powerful tool to detect and locate rail corrugation and that the Corrugram is very simple, effective and useful in signal analysis.
APA, Harvard, Vancouver, ISO, and other styles
46

Jorge, Flávio Miguel da Silva. "High-order Earth-satellite propagation channel measurement and modelling at Ka and Q/V-bands." Doctoral thesis, 2020. http://hdl.handle.net/10773/28937.

Full text
Abstract:
This work focuses on high-capacity spectral-efficient Earth-space microwave communication links, supporting the access to wider and less congested bandwidths and providing the required technological advances on radiowave propagation for the design and operation of system-technologies improving the spectral efficiency, proposing the operation of frequency-reuse schemes and polarization diversity techniques at Ka- and Q/V-bands. Because the suitable planning, successful deployment and effective, spectralefficient and interference-free, operation of all space-borne systems and services is necessarily related and directly dependent, although not exclusively, on the propagation channel conditions, this work provides a comprehensive and systematic approach intending the relevant propagation phenomena characterization and understanding, modelling and mitigation. It is proved that there is a bigger operational margin for the operation of the abovementioned system-technologies than what may be believed by considering the international recommended models. Major challenges are envisaged, specially in what concerns the ice-induced depolarization that is more persistent and takes longer than the corresponding rain-induced effects. Nevertheless, their mitigation is possible for which the depolarization shall be the controlling variable. The time lag of 15 minutes is identified as the best trade-off between affordable time and achievable gain in the framework of a time diversity scheme.
Este trabalho foca-se em links de comunicação Terra-espaço em microondas espectralmente eficientes e de elevada capacidade, suportando o acesso a larguras de banda maiores e menos congestionadas e ofereçendo os avanços tecnológicos necessários em termos de propagação de ondas de rádio para o projeto e operação de tecnologias de sistema que visam o uso otimizado do espectro, propondo a operação de esquemas de reuso de frequência e de técnicas de diversidade de polarização nas bandas Ka e Q/V. Porque o adequado planeamento, a implementação bem sucedida, bem como a efetiva operação, espectralmente eficiente e livre de interferências, de todos os sistemas e serviços espaciais está necessariamente relacionada e diretamente dependente, ainda que não exclusivamente, das condições do canal de propagação, este trabalho oferece uma abordagem completa e sistemática pretendendo a caracterização, compreensão, modelação e mitigação dos fenómenos de propagação relevantes. É provado existir uma maior margem operacional para a operação das tecnologias acima mencionadas do que aquela que se acredita existir considerando os modelos internacionais recomendados. São previstos maiores desafios, especialmente no que concerne à despolarização causada por gelo que é mais persistente e que dura mais tempo do que os correspondentes efeitos causados por chuva. De qualquer forma, a sua mitigação é possível e para a qual a despolarização deverá ser a variável de controlo. O intervalo de tempo de 15 minutos é identificado como o melhor compromisso entre tempo acessível e ganho alcançável no contexto de um esquema de diversidade temporal.
Programa Doutoral em Engenharia Eletrotécnica
APA, Harvard, Vancouver, ISO, and other styles
47

(9820220), Sajith Mohan. "Development of a method for early detection of rail squats using eddy current inspection." Thesis, 2011. https://figshare.com/articles/thesis/Development_of_a_method_for_early_detection_of_rail_squats_using_eddy_current_inspection/13465619.

Full text
Abstract:
"Squats are cracks that are initiated on/near the running surface of the rails and then grow deep into the rail head at a shallow angle.... This thesis details lthe development of an early method for the detectionof rail squats by focusing on the factors that lead to the initiation of squats on rails"--Abstract.
APA, Harvard, Vancouver, ISO, and other styles
48

Fuong, Holly. "Social animals detecting danger: how social relations influence antipredator behavior in a noisy forest." Thesis, 2021. https://doi.org/10.7916/d8-vf2j-n792.

Full text
Abstract:
The risk of death by predation has been a major driver of group living in many prey animals. Animals must adapt to temporal and spatial variation in predation risk and would benefit from using relevant and reliable sources of information both from conspecifics and heterospecifics to better learn about danger. Research on the effects of group living on antipredator strategy has focused largely on group size. However, sociality is often more complex than simple amalgamations of individuals. Those living in groups are likely exposed to unequal levels of predation risk; some are exposed to more danger than others because of factors related to their age, sex, and spatial or social positioning. An individual’s antipredator strategy should reflect its perceived safety levels. I studied antipredator strategies in blue monkeys (Cercopithecus mitis stuhlmanni) in the Kakamega Forest, Kenya. Blue monkeys are arboreal guenons that live in matrilineally-based social groups and form differentiated social relationships. These social relationships could affect how monkeys respond to variable predation risk. Blue monkeys live in dense, biodiverse rain forests and are preyed upon by both aerial and terrestrial predators. They have a well-developed acoustic communication repertoire and have been known to associate with other primates to reduce predation risk (Cords 1987). I conducted five playback experiments and two sets of observational studies, and used data gathered on social interactions among adult females to further our understanding of how group living affects antipredator strategies. I also used 14 years of social interaction data to explore the heritability of social tendencies. In the first chapter, I present a comprehensive literature review of the connections between group living and antipredator behavior. I describe the effects of group size on antipredator behavior and how research on sociality has shifted towards focusing on individuals’ specific relationships and social connectivity. I then describe several ways in which social connectivity has been shown to influence antipredator behavior. I conclude with future directions and then introduce the dissertation. In the second chapter, I focus on heterospecific eavesdropping. I identified the extent to which blue monkey adult females respond to playbacks of alarm and social calls of two syntopic non-predatory bird species—black-faced rufous warblers (Bathmocercus rufus) and joyful greenbuls (Chlorocichla laetissima). Blue monkeys responded differentially depending on both call type and species. I then evaluated differential responses to conspecific and heterospecific callers, hypothesizing that conspecific signals would trigger stronger anti-predator responses because conspecifics are more relevant signals of risk. I conducted a playback experiment in which adult females were presented simultaneously with one alarm or social call from both conspecifics and warblers (4 combinations of alarm and social calls), or ambient rain forest sound (control). Subjects did not differentiate their responses to simultaneous calls according to the type of playback stimulus. These findings suggest that blue monkeys do not differentiate their responses to alarm calls according to caller relevance. Heterogeneous results among different response variables also highlight the importance of examining multiple modes of antipredator behavior. Next, I examine how an individual’s social connectivity influences its antipredator strategy, hypothesizing that more socially connected individuals would benefit from the proximity of more and closely bonded groupmates in enhancing predator avoidance. In Chapter 3, I evaluate the effects of social connectivity on acute antipredator responses, antipredator vigilance, and responses to signals related to various levels of predator-related threat. I first assessed how social connectivity affects the rate at which adult females exhibit acute antipredator responses (such as diving down in trees, climbing up trees, or alarm calling) and the proportion of responses that are major (lasting >30 s), statistically controlling for age, the presence of an infant, and 2-month “seasons”. I predicted that more socially connected individuals would exhibit less frequent acute antipredator responses because they would be better-informed about risk and therefore would exhibit fewer false alarms. I For the same reasons, I also predicted that they would exhibit more major (vs. minor) responses because false alarms are more likely to involve shorter responses (Cords 1987). Contrary to predictions, however, more closely connected individuals exhibited higher rates of acute antipredator responses, which might reflect their enhanced ability to learn about danger from surrounding groupmates, allowing them to detect more potential threats. There was no evidence that social connectivity was associated with the proportion of responses that lasted >30 s. I also found that the rate of acute antipredator responses and the proportion of responses that lasted >30 s varied with season. I then conducted 90-s focal vigilance follows, to assess how long females exhibit antipredator vigilance after controlling for other social and microhabitat factors (e.g., surrounding vegetation density), which can influence conspecific monitoring and exposure to potential predators. I predicted that more well-connected individuals would exhibit lower levels of antipredator vigilance in the absence of any imminent threats and after controlling for other social and spatial factors. More closely connected individuals who were in the spatial center of their social group did spend less time vigilant, but social connectivity was not associated with vigilance times when subjects were at the group’s edge, where exposure to predators and thus predation risk should be highest and antipredator vigilance should generally be higher. In the spatial center of the group, more closely connected individuals should be in a better position to observe their social partners’ antipredator behavior. Microhabitat also influenced antipredator vigilance in multiple ways, which highlights the spatial variation of perceived predation risk in a complex environment. Lastly, I conducted a playback experiment where I examined responses to signals from conspecifics and heterospecifics that are associated with different levels of threat. I predicted that more poorly connected individuals would respond strongly to all signals that might be associated with predators because they must identify personally whether danger is real, whereas more well-connected individuals would have more differentiated responses because they should be near social partners more frequently and can rely on their partners’ antipredator reactions to assess risk levels. However, although subjects did respond more to direct cues of the predator’s presence (its own calls) than to indirect cues of its presence (alarm calls by conspecifics and heterospecifics), there was no evidence that social connectivity affected responses to playbacks. As expected, stimulus type did affect responses—calls from predators (vs. alarm calls or social calls from non-predators) elicited increased looking responses from subjects, which suggests that stimuli that directly signal predator presence will elicit antipredator behavior regardless of the listener’s social connectivity. Overall, social connectivity seems to play a limited role in blue monkeys’ antipredator strategy but there was some evidence that more well-connected individuals were less vigilant when surrounded by groupmates. The ability to distinguish alarm calls by individual callers has not been well-studied, but animals might benefit from making such distinctions if callers vary in how reliably they signal danger. For decades, researchers have tested whether animals can discriminate callers using the habituation-dishabituation paradigm. After habituating subjects by repeatedly presenting calls of one individual, A, they examine whether subjects dishabituate when they hear the calls of a different individual, B (test stimulus). In Chapter 4, I first review studies that used this paradigm to evaluate whether animals discriminate between conspecific callers and then report on two playback experiments which tested whether wild blue monkeys are capable of such discrimination. My review revealed much methodological variation, particularly in the habituation phase and criteria, statistical analysis, and controls. In experiments, I contrasted two methods of habituation, either presenting a fixed number of stimuli (set after pilot observations) or evaluating responses during the series before progressing to the test. Afterwards, I conducted Wilcoxon signed-rank tests to assess habituation statistically. In the first experiment where I played back a fixed number and rate of calls, it was statistically unclear whether subjects habituated to caller A, despite preliminary observations and similar studies that suggested that the experimental design would be appropriate. Because there was not strong evidence that subjects habituated, I did not evaluate statistically whether subjects differentiated between callers in the full dataset. However, in the second experiment where I assessed habituation during the trial, subjects did habituate to caller A and there was weak support that they dishabituated to caller B, which suggests that caller discrimination may occur. From my experiences, I propose an improved design for studies using the habituation-dishabituation paradigm. Lastly, I explore the mechanisms that drive phenotypic variation in social tendencies (and in turn, social connectivity) in adult females. For natural selection to occur, there must be variation in traits, differentiated fitness benefits based on phenotypes, and heredity or a genetic basis underlying phenotypic variation. The previous chapters highlight the variation in and some of the benefits of social connectivity. In Chapter 5, I conducted an exploratory analysis to examine what factors account for phenotypic variance. Using animal models, I found that both environmental and additive genetic variance accounted for some of the phenotypic variance seen in traits associated with social tendencies (using social connectivity as a proxy). Variance in the social environment (i.e., environmental variance) played a large role in shaping observed phenotypic variation in social connectivity. However, all six of the social network measures examined were weakly heritable, which suggests that there is also a genetic basis for behavioral variation, allowing selection to occur. This dissertation emphasizes the importance of examining both antipredator behavior and sociality using multiple experiments, observations, and measures, while also considering the importance of study species and habitat complexity. The relationship between antipredator behavior and social connectivity is not straightforward and can vary greatly between study systems. Although many of my predictions were not supported, I did find evidence that blue monkeys are receptive to heterospecifics, vary their acute antipredator responses and vigilance based on social relationships with conspecifics, adjust their antipredator vigilance according to spatial positioning, and potentially discriminate between alarm callers. The findings presented here expand our knowledge of how animals learn about predation risk by being attentive to conspecifics and heterospecifics.
APA, Harvard, Vancouver, ISO, and other styles
49

Chu, Yung-Hao, and 朱永浩. "Detection of Leading and Passing Vehicles on Highway through Computer Vision in the Rainy Day." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/32563776621709552356.

Full text
Abstract:
碩士
國立中正大學
電機工程研究所
93
This thesis presents the techniques of computer vision and image processing for the detection of highway lanes and vehicles in the rainy day. This system acquires the road scene images from a forward-looking vehicle-mounted camera. After processing and analyzing these images, the system offers the information that the driver needs to improve the traffic safety. In this research, the lane markers are detected by first setting the area of interests in the scene image. We link and group the edge points that are connected, and then apply the least-square-error method to filter these edge-point segments to approximate the lane boundary. On the other hand, by combining the detection of vehicle taillights, the match for taillight pairing, and confirmation of the vehicles characteristic pattern, a reliable way of finding leading vehicles on highway in the rainy day can be derived with the supporting information from the continuous image stream. For neighboring vehicles detection, a scanning scheme is applied to the neighboring lane for detecting the possible vehicle sideline. The algorithm allocates an area of interests, checks the edge-point density and then detects vertical edges in that area to confirm the existence of neighboring vehicles. Testing with a large number of highway images in the rainy day, experimental results show the effectiveness of our proposed schemes; while the image processing time is fast enough to run in real-time on highway.
APA, Harvard, Vancouver, ISO, and other styles
50

Raposo, Tiago Miguel de Góis. "C-RAN CoMP Methods for MPR Receivers." Master's thesis, 2018. http://hdl.handle.net/10362/61580.

Full text
Abstract:
The growth in mobile network traffic due to the increase in MTC (Machine Type Communication) applications, brings along a series of new challenges in traffic routing and management. The goals are to have effective resolution times (less delay), low energy consuption (given that wide sensor networks which are included in the MTC category, are built to last years with respect to their battery consuption) and extremely reliable communication (low Packet Error Rates), following the fifth generation (5G) mobile network demands. In order to deal with this type of dense traffic, several uplink strategies can be devised, where diversity variables like space (several Base Stations deployed), time (number of retransmissions of a given packet per user) and power spreading (power value diversity at the receiver, introducing the concept of SIC and Power-NOMA) have to be handled carefully to fulfill the requirements demanded in Ultra-Reliable Low-Latency Communication (URLLC). This thesis, besides being restricted in terms of transmission power and processing of a User Equipment (UE), works on top of an Iterative Block Decision Feedback Equalization Reciever that allows Multi Packet Reception to deal with the diversity types mentioned earlier. The results of this thesis explore the possibility of fragmenting the processing capabilities in an integrated cloud network (C-RAN) environment through an SINR estimation at the receiver to better understand how and where we can break and distribute our processing needs in order to handle near Base Station users and cell-edge users, the latters being the hardest to deal with in dense networks like the ones deployed in a MTC environment.
APA, Harvard, Vancouver, ISO, and other styles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!