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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Electroluminescence imaging and dark thermography of silicon solar cells with a conventionaldigital camera. / Elektroluminescensavbildning och mörk termografi av kiselsolceller med en konventionell digitalkamera.

Lama, Arjun January 2021 (has links)
The aim of the thesis is to suggest a comprehensive and inexpensive method of diagnosing the solar cell quality via a conventional digital camera. The following questions are answered, Can a conventionaldigital camera be used for diagnosing the quality of solar cells?; If so,is the experimental setup for the quality diagnosing constrained to a laboratory and single solar cells or can it be done in a private home for a full-sized solar panel?; What are the defects that can be observed in this experiment? A conventional digital camera has been modified to acquire the electroluminescence (EL) images and dark thermography(RevEL) images. The experiment has been done in two locations with different types of samples. Multi-crystalline p-type single solar cells are used during the laboratory experiment. In the experiment set up at the private home, a conventional solar panel with 36 quadraturemulti crystalline silicon solar cells, that are equivalent to 9 full solarcells, is used. The EL imaging has been performed under the forward bias whereas the dark thermography imaging has been performed under reverse bias. The contrast in EL images is due to the radiativeand non-radiative recombination of injected excess minority charge carriers. A large non-radiative recombination site produces a large dark area in the EL image. Similarly, the contrast in RevEL images is due to the generation of charge carriers that are associated with the non-radiative recombination sites in the depletion layer. A large defect area produces a large bright area in the RevEL image. Hence,the EL image and the RevEL image are some what inverted images of each other. It is also found that the IV characteristics and the semi-log curves are in a good agreement with the EL and the RevEL images. When the EL image is combined with the hand-on devices like a mobile camera and a macro lens, it reveals defected areas like finger-interruptions, microcracks, grain boundaries and planar defects. Whereas the RevEL images, when combined with the image processing software tool, reveal the morphology of the defected sites. This justifies the beauty and the simplicity of using an every day digitalcamera as a diagnostic tool for the quality control of the solar cell
32

Neue Ansätze zur Auswertung und Klassiffizierung von sehr hochauflösenden Daten

Hoffmann, Andrea 10 May 2001 (has links)
Auf dem Luftbildsektor vollziehen sich seit einigen Jahren grundsätzliche Veränderungen. Digitale flugzeuggetragene Kamerasysteme und hochauflösende Satellitensysteme bieten neue Potentiale der Datenakquise und -auswertung. Diese digitalen Datensätze werden in absehbarer Zeit das herkömmliche Luftbild ersetzen und Kartographie, Photogrammetrie und Fernerkundung erheblich verändern. Die neue Generation von digitalen Kameras wird zwei zentrale Bereiche der Kartographie einschneidend beeinflussen: Die Orthokartenherstellung und die Kartenaktualisierung. Der Bedarf aktueller Geobasisdaten macht Orthobilder besonders für Geoinformationssysteme interessant. Bisher standen als Basisdaten für Orthobildkarten großer Auflösung (> 1:10 000) lediglich Luftbilder zur Verfügung. Es wird gezeigt, daß die digitalen Daten der neuen Kamerageneration zur Erstellung von Orthobildkarten operationell einsetzbar sind. Durch die automatisierte Prozessierung werden sie den Anforderungen an schnelle aktuelle Kartenprodukte gerecht, mit ihrer hochgenauen Navigation bieten die digitalen Systeme die automatisierte Erstellung geometrisch sehr genauer Datensätze, die mit herkömmlichen Mitteln nur sehr aufwendig erreicht werden könnten. Ein Vergleich mit Luftbildern zeigt und bewertet die Unterschiede beider Aufnahmesysteme. Untersucht wurden Datensätze der digitalen Kamera HRSC-A des DLR Adlershof. Mit der HRSC-A (High Resolution Stereo Camera - Airborne) und der speziell für die Prozessierung dieser Daten entwickelten Software steht den Geoinformationsnutzern erstmals ein operationelles System zur Verfügung, das vollständig digital und vollautomatisch hochauflösende Orthobilddaten produziert. Die Pixelauflösung liegt zwischen 10 und 40 cm (Flughöhe von 2500 bis 10 000 m). Als vorteilhaft für die Analyse erweist sich die gleichzeitige Verfügbarkeit von hochauflösenden panchromatischen und multispektralen Datensätzen, die Verfügbarkeit eines hochauflösenden Geländemodells (x,y: 50 cm bzw. 1m, z: 10 cm) und die hohe Genauigkeit der Datensätze. Die Arbeit diskutiert die Problematik einer automatisierten Auswertung hochauflösender Daten. Diese Datensätze stellen neue Anforderungen an Auswertungsverfahren. Der Detailreichtum erschwert die Interpretation, gröbere räumliche Auflösungen glätten die Komplexität innerhalb heterogener Landnutzungen (besonders in urbanen Gebieten) und erleichtern so eine automatische Interpretation. Es wird gezeigt, daß "klassische" Auswertungsmethoden wie pixelbasierte Klassifizierungen (überwacht oder unüberwacht) zur Auswertung der hochauflösenden Daten nur bedingt geeignet sind. Im Rahmen der Arbeit werden zwei neue Ansätze entwickelt und untersucht, die nicht mehr pixelweise, sondern flächenhaft und objektorientiert arbeiten. Ein per-parcel-Ansatz zeigt gute Ergebnisse bei der Auswertung. Das Verfahren ermittelt zunächst mittels einer unüberwachten Klassifizierung Szenekomponenten in definierten Untereinheiten (parcel), die den Inhalt des Datensatzes repräsentieren. Die klassifizierten Pixel innerhalb der definierten parcel-Einheiten werden anschließend extrahiert und ihr Verhältnis zueinander weiter ausgewertet. Ergebnis ist zunächst die prozentuelle Verteilung der Szenekomponenten in den Einheiten, anschließend werden Zusammenhänge zwischen den vorhandenen Komponenten und der Landoberfläche definiert. Untersucht wurde ferner ein objektorientierter Ansatz, der die Interpretation von Einzelobjekten erlaubt. Hierbei wird das Bild in homogene Objekte segmentiert, die die Grundlage für die weitere Analyse bilden. Der diskutierte Ansatz besteht aus zwei Strategien: Mittels multiskalarer Segmentierung wird der Bilddatensatz zunächst in Einheiten strukturiert, verschiedene Maßstabsebenen sind gleichzeitig verfügbar. Grundidee ist die Schaffung eines hierarchischen Netzes von Bildobjekten. Diese gefundenen Einheiten werden anschließend spektral mittels Nearest Neighbour oder wissensbasiert mittels Fuzzy Logic Operatoren klassifiziert. Der Ansatz zeigt überzeugende Ergebnisse bei einer automatisierten Hauserkennung und der Aktualisierung bestehender Vektordatensätze. Die Einteilung der Bilddaten in Segmente, also zunächst eine Abstrahierung der Information vom Einzelpixel zu größeren semantischen Einheiten und die weitere Bearbeitung dieser Segmente erwies sich als sinnvoll. Es wurde ferner gezeigt, daß für die Analyse in städtischen Räumen die Einbeziehung von Oberflächeninformation unbedingt erforderlich ist. Durch die spektrale Ähnlichkeit von Bildelementen bietet die Einbeziehung des Oberflächenmodells die Möglichkeit, mittels einer zusätzlich bekannten Information über die Höhe der Objekte, diese Klassen zu trennen. / Remote sensing goes through times of fundamental changes. New digital airborne camera systems offer new potentials for data aquisition and interpretation. These data sets will replace aerial photography in the near future and change photogrammetry, cartography and remote sensing. The new camera generation will influence two central domains of cartography: Orthomap production and map updating. As a base for in-time updating orthomaps became more and more important. Up to now large scale mapping (scales > 1:10,000) is done nearly exclusively with aerial photographs. It can be shown that the digital data sets of the new camera generation can be used operationally for the production of orthomaps. A fully automated processing line provides the ortho images very shortly after aquisition, due to the used high precision navigation system the accuracy of the data is very high, even very big scales can be realized. A comparison of digital cameras and aerial photos discusses and rates the properties of the different aquisition systems and data sets. For interpretation data sets of the digital camera HRSC-A were used. The High Resolution Stereo Camera - Airborne (HRSC-A) digital photogrammetric camera and its processing software provides the geoinformation industry for the first time with an entirely digital and fully automatic process to produce highly accurate digital image data. The pixel size ranges between 10 and 40 cm (flight altitude 2500 - 10,000 m). The airborne camera combines high resolution, photogrammetric accuracy and all-digital acquisition and provides both multispectral and elevation information. The pushbroom instrument provides digital ortho-images and digital surface models with an accuracy of 10-20 cm. The use of this wide range of image information showed to be very helpful for data analysis. This investigation focuses on the problems of automated interpretation of high-resolution data. These data sets make high demands on automated interpretation procedures. The richness of details depicted in the data sets complicates the interpretation, coarser spatial resolutions smooth out spatial complexity within heterogeneous land cover types, such as urban, and make an automated interpretation easier. This report shows that conventional interpretation techniques like pixelbased classification (supervised or unsupervised) do not lead to satisfactory results. Two new object-oriented and region-oriented approaches for the interpretation of high resolution data sets were developped and discussed. The parcel-based approach showed good results in interpretation of the data. The proposed methodology begins with an unsupervised per-pixel classification to identify spectral clusters which represent the range of scene components present in the pre-defined land parcels. The per-parcel analysis extracts the pixels classified as scene components within the land parcel under examination and calculates the total numbers and fractions for each scene component present. To identify land cover types not represented by scene components at the land parcel level, it is necessary to process the scene component information and infer relationships between the scene components present and land cover type. A set of rules was devised to identify a range of land cover types from the mixtures of scene components found within each land parcel. Secondly an object-oriented and multi-scale image analysis approach was used for the interpretation of single objects. The procedure contains two basic domains. The strategy is to build up a hierarchical network of image objects which allows to represent the image information content at different resolutions (scales) simultaneously. In a second step the image objects were classified by means of fuzzy logic, either on features of objects and/or on relations between networked objects operating on the semantic network. The procedure showed very good results in detecting houses and updating vector data sets. Segmenting the data in semantic units and performing further analysis on these units showed to be very helpful for interpretation. It could be shown that for analysis of urban areas the use of a Digital Surface Model is necessary. Due to the spectral similarities of image elements the elevation information offers an important additional tool for analysis.
33

Δημιουργία φασματικής εικόνας με ψηφιακή φωτογραφική μηχανή και την χρήση πολλαπλών φίλτρων

Γκίκας, Κώστας 13 January 2015 (has links)
Σκοπός της διπλωματικής είναι η κατασκευή συστήματος που θα δημιουργεί φασματική απεικόνιση αντικειμένων χρησιμοποιώντας μια απλή ψηφιακή φωτογραφική μηχανή και φίλτρα τα οποία θα εναλλάσσονται μπροστά στον φακό της μηχανής με την βοήθεια βηματικού κινητήρα. / The aim of the project is the construction of a system that creates spectral imaging objects using a simple digital camera and filters which rotates in front of the camera lens by means stepper motor.
34

Tvorba prezentací jako výukových materiálů pro vzdělávací oblast Člověk a svět práce / Design of presentations as taeching materials for educational area "Člověk a svět práce"

KAHOVCOVÁ, Eva January 2009 (has links)
This diploma thesis is dealing with the presentation of technical topic The usage of digital technologies from the educational program The human being and the work-world a with the didactical elaboration of this topic, specific to the theoretical section of Peripheral equipment of the PC and Digital camera. In the theoretical part of this thesis is written the characteristics of the educational program The human being and work-world and didactical technique needed to this topic. Next part is about how to use the PC at schools, and how to include the presentations to the education in light of the concept called Users conception of technical subjects{\crq} education. In the practical part of this thesis I try to suggest the detailed topics of Peripheral equipment of the PC and Digital camera education. The presentations were created to all theoretical knowledge and next step was the each topic methodology elaboration. The methodology was created to be able to suggest various kind of pupils{\crq} work and various educational tools. The thesis also contains the practical attestation of this suggest at basic school. This thesis provides the instruction, how to educate the topic The digital technologies usage especially for the technical education students.
35

Testování spotřebních produktů na základě preferencí spotřebitelů / Consumer preferences' based testing of consumer products

VALDMANOVÁ, Markéta January 2009 (has links)
I used questionnaire investigation to reach the goal of my thesis. I wanted to ascertain the behaviour of users in the market when using the relevant product and to establish the importance of the attributes of digital camera for the user on the base of the research. Further my task was to set the weights of the individual attributes for multi-criteria decision-making. To compare the offered products with the help of the selected technique of multi-criteria decision-making and to suggest suitable products for the users on the base of the weights found out. The ascertained data and results will be further utilizable for consumer organizations, specifically for the Spotřebitelský institut SOS, o.p.s. (SOS Consumer institute, quasi-public company). I came to the following results after having evaluated my research. Most respondents own digital cameras, most frequently brand PANASONIC, CANON and OLYMPUS. The highest percentage of respondents use their cameras to record the personally significant moments, identically most frequently several times a week or several times a month. The main reason to choose a new camera is its function and price and the users are most frequently ready to spend between 3 001,- and 9 000,- CZK. Respondents prefer black and silver digital camera. As I supposed that there would be certain differences among the parameter preferences between genders and experiences of the users, I divided the respondents into individual segments in which I performed my further research. If I should assess the parameters most preferred by the respondents, there are certain differences between genders and experiences of the users. It is possible to say generally, on the base of the ascertained highest values of weights, that all user segments prefer the following parameters: noise (sensitivity), camera speed, battery durability, megapixel resolution and optic zoom. The clearly unimportant parameter is the possibility of printing directly from the camera that is on the last place of importance in all segments. I compared 25 digital cameras on the base of multi-criteria decision-making and the ascertained weights. I can recommend more or less the following 7 suitable products to the individual segments: Canon PowerShot SX1 IS, Panasonic Lumix DMC-FX500, Canon EOS 40D, Canon Ixus 870 IS, Casio EX-V7, Canon EOS 50D, Nikon D300.
36

Statisk deformationsmätning med fotobaserad skanning : Utförd med icke-professionella digitalkameror

Jonsson, Anna, Eriksson, Pernilla January 2019 (has links)
Till följd av den utveckling som skett hos digitalkameror och programvaror för bildbehandling de senaste åren har intresset för fotobaserad skanning (FBS) vuxit. I denna studie utvärderades FBS som ett alternativ till terrester laserskanning (TLS) för statisk deformationsmätning och relaterade till kavitationsskador på vattenturbinkolvar där volym och maxdjup mäts. En stor del av syftet var att det skulle göras med simpla förutsättningar så att metoden blir enkel att utföra och tillämpbar framförallt i industrimiljöer. Simulerade deformationer skapades på en bräda i trä med en plan omgivande yta och på en boll i kork för att också undersöka en välvd yta. Fotograferingen utfördes med icke-professionella kameror, en digitalkamera och en smartphonekamera. Objekten som undersöktes hade en matt textur, bilderna togs med stor övertäckning (80–100%) och ljusförhållandena var goda för att undvika skuggning och blänk i bilderna. Det som utvärderades i studien var hur många kodade markörer som bör användas som konnektionspunkter för att förbättra bildmatchningen, optimalt antal skalstockar för skalsättning och vilken kameramodell och självkalibreringsmodell som gav den lägsta mätosäkerheten. Bildmatchningen och skapandet av 3D modellerna utfördes i programvaran Agisoft Photoscan. Analysen av modellerna utfördes i programvarorna 3DReshaper och CloudCompare. Resultaten utvärderades mot en skannad referensmodell framtagen med en ROMER Absolute Arm som har möjlighet att uppvisa mätosäkerheter på hundradels mm och kunde därmed anses som “sant” värde i denna studie. Resultatet visade att de kodade markörerna inte var nödvändiga som konnektionspunkter för bildmatchningen. Det visade även att oavsett kamera, självkalibreringsmodell och antal skalstockar (4, 3 & 2) låg alla modeller under den tillåtna avvikelsen i volym och maxdjup som normen för kavitationsskador på vattenturbinkolvar föreskriver (IEC 60609-1, från Swedish Standards Institute). Normen anger att mätosäkerheten på metoden som används inte får överskrida ±15% från det sanna värdet. Den här metoden har här visat sig vara tillämpbar och kan ersätta TLS för dokumentation och avgjutning för uppmätning av statiska deformationer när kraven på en relativ mätosäkerhet är ±5% av det sanna värdet. / As a result of the development of digital cameras and image processing software in recent years, the interest in close-range photogrammetry (CRP) has grown. In this study, CRP was evaluated as an alternative method to terrestrial laser scanning (TLS) for static deformation measurements and it was related to cavitation damage on water turbine pistons where the volume and maximum depth is measured. A large part of the purpose of the study was that it should be done with simple conditions so that the method will be easy to carry out and applies especially in industrial environments. Simulated deformations were created on a wooden board with a flat surrounding surface, and on a ball made of cork. The shooting was done with non-professional cameras, a digital camera and a smartphone camera. The objects that was examined had a matte texture, the images were taken with a large overlap (80–100%) and the lighting conditions were good enough to avoid shading and glare in the pictures. What was evaluated in the study was how many coded markers that should be used to improve image alignment, what the optimal number of scale bars for scaling the model is, and which camera model and self-calibration model that gave the lowest measurement uncertainty. The alignment of the images and creation of the 3D-models of the deformations were performed in the software Agisoft Photoscan. The analysis of the models was performed in the softwares 3DReshaper and CloudCompare. The results were evaluated against a scanned reference model developed with a ROMER Absolute Arm which has the ability to display measurement uncertainties on hundreds of millimetres and could thus be considered as a “true” value in this study. The result showed that the coded markers were not necessary in the image alignment procedure. It also showed that, regardless of which camera, self- calibration model and number of scale bars (4, 3 & 2), all the models created were below the permitted deviation in volume and maximum depth as the standard for cavitation damage on water turbine pistons (IEC 60609-1, from the Swedish Standards Institute) prescribes. The standard states that the measurement uncertainty of the method used must not exceed ±15% from the true value. This method has been found to be applicable and can replace TLS for documentation and volume measurement with a temporary filler for static deformations when the requirements for a relative measurement uncertainty are ±5% from the true value.
37

Srovnání konvenčních a nových metod měření a hodnocení jasů / Comparison of Conventional and New methods of Measurement and Evaluation of Luminance

Svoboda, Miloslav January 2012 (has links)
Because luminance is the only value to which our sight responds, its measurement becomes important in terms of ensuring the proper function of vision. Nowadays luminance measuring can be made by conventional methods, such as direct using of luminance meter. However an entirely new method of measuring luminance levels is coming. This method is based on using luminance analyzers which work using a digital photography for the analysis of luminance. This thesis deals with these issues and is divided into several chapters, which form the two main parts of the thesis, the theoretical and the practical one. The theoretical part of the thesis deals with the basics of lighting technology, as well as the principles of measuring the luminance using conventional methods. New methods of measurement, i.e. using luminance analyzers, are discussed in two chapters which analyse both the principle and characteristics of analyzers available today. In the practical part is a comparative measurement carried out – in the laboratory and in terrain – using both methods.
38

Analýza tvorby třísky pomocí digitální vysokorychlostní kamery / Analysis of chip forming mechanism with a high-speed digital camera

Tichý, Vojtěch January 2015 (has links)
This thesis covers matters related to high-speed digital cameras and their usage in various spheres of human activities, mainly in research of chip forming. Thesis summarises important knowledge needed for creation of high-speed recordings and choice of suitable lenses. Focus is taken on creation of high-speed recordings of chip forming process in turning operation outside grooving by using of different types of chipformers. Main goal is to verify its functionality in specific value range of feed per revolution.
39

Desarrollo de un equipo electrónico portátil orientado a la evaluación del estado de limpieza de conectores de fibra óptica haciendo uso de un microscopio óptico y algoritmos de procesamiento digital de imágenes / Development of a portable electronic equipment aimed at evaluating the state of cleanliness of fiber optic connectors using an optical microscope and digital image processing algorithms

Chavez Muñoz, Javier Gustavo, Fernandez Salazar, Victor Rodolfo 27 February 2020 (has links)
Concluypo enmbargo. / Solicitud de envío manuscrito de artículo científico. / El presente trabajo propone un dispositivo electrónico portátil que, acoplado a un microscopio óptico convencional, pueda capturar una imagen microscópica de la fibra óptica y emita un juicio si el conector se encuentra en un estado de limpieza aceptable o no. Asimismo, mediante reportes de trabajo y usando normas internacionales, evaluar los conectores para que formen parte de una base de datos histórica que aporte a los mantenimientos preventivos de una red. Si bien en la actualidad se tienen soluciones tecnológicas parecidas, estas tienen como gran desventaja el alto costo que implica adquirir uno de estos equipos, desanimando a los operadores optar por este importante equipo. Ingenierilmente, esta propuesta será posible mediante el desarrollo de un algoritmo que procese las imágenes capturadas con el uso de diversas herramientas de procesamiento de imágenes como la binarización, transformada de Hough, algoritmo de Canny, escala de grises y ecualización de imágenes, que, montado sobre un hardware basado en un computador de placa reducida, entregará una evaluación del conector de fibra óptica y un reporte descargable que sirve como documentación del trabajo realizado. Dentro de este contexto, los resultados obtenidos son favorables para una utilización en campo, para llegar a esto se tuvo como como variable de calidad el índice de Kappa Cohen, en el cual se demuestra la alta tasa de coincidencia entre las evaluaciones del equipo y la evaluación de ingenieros expertos. / The present work proposes a portable electronic device that, coupled with a conventional optical microscope, can capture a microscopic image of the optical fiber and emit a judgment if the connector is in an optimal cleaning state or not. Likewise, through reports and using international standards, evaluate the connectors so that can be part of a source of database that contributes to the preventive maintenance of a network. Although similar technological solutions are currently available, these have the great disadvantage of the high cost of acquiring one of this equipment, discouraging operators from opting for this important procedure. Engineeringfully, this proposal will be possible through the development of an algorithm that processes the captured images with the use of various image processing tools such as binarization, Hough transform, Canny algorithm, grayscale and image equalization, which, mounted on a hardware based on a reduced plate computer, it will provide an evaluation of the fiber optic connector and a downloadable report that serves as documentation of the work done. Within this context, the results obtained are favorable for a field use, to achieve this, the Kappa Cohen index was used as a quality variable, which demonstrates the high rate of coincidence between the evaluations of the equipment and the Evaluation of expert engineers. / Tesis
40

Perspectives of multimode fibers and digital holography for optogenetics

Czarske, Jürgen W., Haufe, Daniel, Koukourakis, Nektarios, Büttner, Lars 08 August 2019 (has links)
Optogenetic approaches allow the activation or inhibition of genetically prescribed populations of neurons by light. In principle, optogenetics offers not only the ability to elucidate the functions of neural circuitry, but also new approaches to a treatment of neurodegenerative diseases and recovery of vision and auditory perception. Optogenetics already has revolutionized research in neuroscience. However, new methods for delivering light to three-dimensionally distributed structures e.g. in the brain are necessary. A major hurdle for focusing light through biological tissue is the occurring scattering and scrambling of the light. We demonstrate the correction of the scrambling in a multimode fiber by digital optical phase conjugation with a perspective for ptogenetics.

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