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1
Müller, Ingmar. "Linking detector radiometry from milliwatts radiant power to single photons." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16883.
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Das Ziel dieser Dissertation ist das Schließen der radiometrischen Lücke zwischen der klassischen Radiometrie und der Radiometrie im Bereich weniger und einzelner Photonen. In dieser Arbeit wurden dazu zwei wesentliche Themen bearbeitet. Erstens, die Charakterisierung und Validierung eines neuen radiometrischen Detektorprimärnormals für den Wellenlängenbereich von 400 nm bis 800 nm basierend auf Silizium-Photodioden. Dieses neuartige Primärnormal kann sowohl in der Radiometrie im Bereich weniger Photonen als auch in der klassischen Radiometrie eingesetzt werden, der sogenannte “Predictable Quantum Efficient Detector” (PQED). Der PQED wurde im Rahmen dieser Arbeit charakterisiert und experimentell validiert. Für die Validierung war es nötig, die relativen Unsicherheiten der klassischen Radiometrie und insbesondere der Kryoradiometrie, deutlich zu verringern. Mit der Inbetriebnahme eines neuen Kryoradiometers wurde das Ziel, in den Unsicherheitsbereich von ca. 10E−5 vorzudringen, erreicht. Zweitens, es wurde eine Kalibriermethode für Einzelphotonendetektoren eingesetzt, rückgeführt auf das internationale Einheitensystem, die auf den einzigartigen Eigenschaften von Synchrotronstrahlung basiert. Diese Methode kann benutzt werden um sowohl Freistrahl- als auch fasergekoppelte Einzelphotonendetektoren bei praktisch jeder gewünschten Wellenlänge zu kalibrieren und erreicht im Moment die weltweit geringsten Messunsicherheiten. Mit dem neuen Kryoradiometer, dem PQED und dem auf Synchrotronstrahlung basierenden Kalibrierverfahren sind die erreichbaren Messunsicherheiten in der Radiometrie im Bereich von wenigen Photonen bis zu Strahlungsleistungen im Milliwattbereich deutlich reduziert worden.This thesis addresses the bridging of the radiometric gap in the transition from classical radiometry to the few and single photon radiometry. In this context, two main tasks were emphasised. First: A new radiometric primary detector standard for wavelengths between 400 nm and 800 nm, suitable for classical and few photon radiometry, the so-called “Predictable Quantum Efficient Detector” (PQED) was characterised and validated. For the validation of the PQED, the relative uncertainties achievable in classical radiometry and, in particular, with cryogenic radiometers had to be reduced to a level of 10E−5 with the commissioning of a new cryogenic radiometer facility. Second: A calibration method for single photon detectors in the visible and NIR has been used which is based on the unique properties of synchrotron radiation. This calibration method allows radiometric single photon detector calibrations with the lowest uncertainties reported so far. This method can be used to calibrate free space and fibre-coupled single photon detectors traceable to the international system of units at practically every desired optical wavelength. With the new cryogenic radiometer, the PQED, and the calibration method based on synchrotron radiation, the uncertainties in radiometry have been significantly reduced in the range from milliwatts of radiant power down to attowatts corresponding to a few photons per second.
2
Pfab, Jonathan Francis. "Thermal Analysis of the Detector in the Radiation Budget Instrument (RBI)." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/82035.
Full textAbstract:
Earth radiation budget instruments are devices designed to study global climate change. These instruments use telescopes embarked on low-earth-orbit satellites to measure Earth emitted and reflected solar radiation. Radiation is sensed as temperature changes caused by radiation absorbed during scans of the earth on a delicate gold-black coated detector. This work is part of a larger effort to develop an end-to-end dynamic electro-thermal model, based on first-principles, for the next generation of earth radiation budget instruments, the Radiation Budget Instrument (RBI). A primary objective of this effort is to develop a numerical model of the detector to be used on RBI. Specifically, the sensor model converts radiation arriving at the detector, collimated and focused through telescopes, into sensible heat; thereby producing a voltage. A mathematical model characterizing this sensor is developed. Using a MATLAB algorithm, an implicit finite-volume scheme is implemented to determine the model solution. Model parameters are tuned to replicate experimental data using a robust parameter estimation scheme. With these model parameters defined, the electro-thermal sensor model can be used, in conjunction with the remaining components of the end-to-end model, to provide insight for future interpretation of data produced by the RBI.Master of Science
3
Quick, Mason G. "Calibrated, Multiband Radiometric Measurements of the Optical Radiation from Lightning." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/325230.
Full textAbstract:
Calibrated, multiband radiometric measurements of the optical radiation emitted by rocket-triggered lightning (RTL) have been made in the ultraviolet (UV, 200-360 nm), the visible and near infrared (VNIR, 400-1000 nm), and the long wave infrared (LWIR, 8-12 µm) spectral bands. Measurements were recorded from a distance of 198 m at the University of Florida International Center for Lightning Research and Testing (ICLRT) during the summers of 2011 and 2012. The ICLRT provided time-correlated measurements of the current at the base of the RTL channels. Following the onset of a return stroke, the dominant mechanism for the initial rise of the UV and VNIR waveforms was the geometrical growth of the channel in the field-of-view of the sensors. The UV emissions peaked about 0.7 µs after the current peak, with a peak spectral power emitted by the source per unit length of channel of 10 ± 7 kW/(nm-m) in the UV. The VNIR emissions peaked 0.9 µs after the current peak, with a spectral power of at 7 ± 4 kW/(nm-m). The LWIR emissions peaked 30-50 µs after the current peak, and the mean peak spectral power was 940 ± 380 mW/(nm-m), a value that is about 4 orders of magnitude lower than the other spectral band emissions. In some returns strokes the LWIR peak coincides with a secondary maximum in the VNIR band that occurs during a steady decrease in channel current. Examples of the optical waveforms in each spectral band are shown as a function of time and are discussed in the context of the current measured at the channel base. Source power estimates in the VNIR band have a mean and standard deviation of 2.5 ± 2.2 MW/m and are in excellent agreement with similar estimates of the emission from natural subsequent strokes that remain in a pre-existing channel which have a mean and standard deviation of 2.3 ± 3.4 MW/m. The peak optical power emitted by RTL in the UV and VNIR bands are observed to be proportional to the square of the peak current at the channel base. The same trend was found for natural lightning using peak currents estimates provided by the National Lightning Detection Network. Ratios of the optical power to the electromagnetic power emitted at the time of peak current suggest the radiative efficiency in the VNIR band is a few percent during the early onset of a return stroke. The majority of return strokes in RTL are found to emit most of their optical energy during the initial impulse phase.
4
Müller, Ingmar [Verfasser], Oliver [Akademischer Betreuer] Benson, Mathias [Akademischer Betreuer] Richter, and Achim [Akademischer Betreuer] Peters. "Linking detector radiometry from milliwatts radiant power to single photons / Ingmar Müller. Gutachter: Oliver Benson ; Mathias Richter ; Achim Peters." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://d-nb.info/104716888X/34.
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5
Fernandes, Luís Olavo de Toledo 1978. "Desenvolvimento de fotômetros THz para observação de explosões solares." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259238.
Full textAbstract:
Orientadores: Jacobus Willibrordus Swart, Pierre KaufmannDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: O telescópio solar submilimétrico operando nas freqüências de 212 e 405 GHz detectou uma nova componente espectral das emissões de explosões solares, com máximo em algum ponto da faixa Terahertz, simultaneamente com a conhecida componente espectral em microondas, trazendo sérios desafios para interpretação. O diagnostico deste tipo de emissão transiente em freqüências THz traz desafios tecnológicos que são objetivo deste estudo. Este projeto consiste em um estudo das características de filtros e sensores não refrigerados para aplicação em projeto aeroespacial na faixa Terahertz do espectro eletromagnético. Foram estudados e caracterizados detectores bolométrico, piroeletrico, e optoacustico, precedidos por filtros passa-baixa que suprimem a radiação na faixa do visível e infravermelho próximo do espectro eletromagnético, filtros passa-banda centrados na freqüência THz desejada, e modulador mecânico. O detector a célula de Golay mostrou ser o mais sensível. Foi selecionado para o protótipo de fotômetro THz que serviu para definir parâmetros de projeto para o modelo de vôo, para observação solar fora da atmosfera terrestre, em balões estratosféricos, satélites, ou estações no solo com atmosfera excepcionalmente transparente. O sistema foi concebido para observar todo o disco solar e detectar pequenas variações relativas de temperatura causadas por explosões em regiões especifica do Sol. Obteve-se mínima detectabilidade de variações relativas de temperatura da ordem de 1 K com resolução temporal de subsegundo
Abstract: The solar submillimeter-wave telescope, operating at 212 and 405 GHz frequencies detected a new flare spectral component emission, peaking in the THz range, simultaneously with the well known microwaves component, bringing challenging constrains for interpretation. The diagnostics of this kind of transient emission at THz frequencies also bring technical challenges, which are the subject of this study. The project consists in a study of the characteristics of filters and uncooled detectors for aerospace project application at THz range of the electromagnetic spectrum. Three types of uncooled sensors were tested: bolometric, pyroelectric, and optoacoustic, proceeded by low-pass filters to suppress the visible and infrared radiation, band-pass filter centered at THz frequency, and a chopper. The Golay cell sensor was considered the most sensible detector of all, and was selected for the photometer prototype THz system to observe the Sun outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. The system was designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions of the Sun. The minimum relative temperature variation detected was about 1 K with subsecond time resolution
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
6
Lehtomäki, J. (Janne). "Analysis of energy based signal detection." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514279255.
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Abstract
The focus of this thesis is on the binary signal detection problem, i.e., if a signal or signals are present or not. Depending on the application, the signal to be detected can be either unknown or known. The detection is based on some function of the received samples which is compared to a threshold. If the threshold is exceeded, it is decided that signal(s) is (are) present. Energy detectors (radiometers) are often used due to their simplicity and good performance. The main goal here is to develop and analyze energy based detectors as well as power-law based detectors.
Different possibilities for setting the detection threshold for a quantized total power radiometer are analyzed. The main emphasis is on methods that use reference samples. In particular, the cell-averaging (CA) constant false alarm rate (CFAR) threshold setting method is analyzed. Numerical examples show that the CA strategy offers the desired false alarm probability, whereas a more conventional strategy gives too high values, especially with a small number of reference samples.
New performance analysis of a frequency sweeping channelized radiometer is presented. The total power radiometer outputs from different frequencies are combined using logical-OR, sum and maximum operations. An efficient method is presented for accurately calculating the likelihood ratio used in the optimal detection. Also the effects of fading are analyzed. Numerical results show that although sweeping increases probability of intercept (POI), the final probability of detection is not increased if the number of observed hops is large.
The performance of a channelized radiometer is studied when different CFAR strategies are used to set the detection threshold. The proposed iterative methods for setting the detection threshold are the forward consecutive mean excision (FCME) method with the CA scaling factors in final detection decision (FCME+CA), the backward consecutive mean excision (BCME) method with the CA scaling factors in detection (BCME+CA) and a method that uses the CA scaling factors for both censoring and detection (CA+CA). Numerical results show that iterative CFAR methods may improve detection performance compared to baseline methods.
Finally, a method to set the threshold of a power-law detector that uses a nonorthogonal transform is presented. The mean, variance and skewness of the decision variable in the noise-only case are derived and these are used to find a shifted log-normal approximation for the distribution of the decision variable. The accuracy of this method is verified through simulations.
7
Mason, Graeme. "Test and calibration of the Along Track Scanning Radiometer, a satellite-borne infrared radiometer designed to measure sea surface temperature." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293406.
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8
Guner, Baris. "Studies of Radio Frequency Interference Detection Methods in Microwave Radiometry." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1238780286.
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9
Mlwilo, Nolasco Anton. "Radiometric characterisation of vineyard soils, Western Cape, South Africa." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6358_1318594333.
Full textAbstract:
This study is aimed at investigating the feasibility of using the radiometric technique as an alternative to traditional methods for determining soil physico-chemical parameters which are important for terroir characterization. In-situ and ex-situ radiometric analyses of soil from three vineyard blocks of Simonsig Wine Estate in the Stellenbosch district (Western Cape, South Africa) were studied. A mobile MEDUSA gamma-ray detection system comprising a CsI(Na) crystal (length 15 cm, diameter 7 cm) and associated electronics mounted on a portable trolley were used for partial terroir characterisation. Thereafter activity concentrations of 40K, 232Th series and 238U series in soil (top ~30 cm) from the measured MEDUSA spectra (0 â 3 MeV) were extracted by means of the full-spectrum analysis (FSA) method. A lead-shielded HPGe detector was used for analyzing collected soil samples while soil physico-chemical parameters were analysed using standard methods at research and commercial laboratories.
10
HOLM, RONALD GENE. "THE ABSOLUTE RADIOMETRIC CALIBRATION OF SPACE-BASED SENSORS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184113.
Full textAbstract:
The need for absolute radiometric calibration of space-based sensors will continue to increase as new generations of space sensors are developed. A reflectance-based in-flight calibration procedure is used to determine the radiance reaching the entrance pupil of the sensor. This procedure uses ground-based measurements coupled with a radiative transfer code to characterize the effects the atmosphere has on the signal reaching the sensor. The computed radiance is compared to the digital count output of the sensor associated with the image of a test site. This provides an update to the preflight calibration of the system and a check on the on-board internal calibrator. This calibration procedure was used to perform a series of five calibrations of the Landsat-5 Thematic Mapper (TM). For the 12 measurements made in TM bands 1-3, the RMS variation from the mean as a percentage of the mean is (+OR-) 1.9%, and for measurements in the IR, TM bands 4,5, and 7, the value is (+OR-) 3.4%. The RMS variation for all 23 measurements is (+OR-) 2.8%. The absolute calibration techniques were put to another test with a series of three calibration of the SPOT-1 High Resolution Visible, (HRV), sensors. The ratio, HRV-2/HRV-1, of absolute calibration coefficients compared very well with ratios of histogrammed data obtained when the cameras simultaneously imaged the same ground site. Bands PA, B1 and B3 agreed to within 3%, while band B2 showed a 7% difference. The procedure for performing a satellite calibration was then used to demonstrate how a calibrated satellite sensor can be used to quantitatively evaluate surface reflectance over a wide range of surface features. Predicted reflectance factors were compared to values obtained from aircraft-based radiometer data. This procedure was applied on four dates with two different surface conditions per date. A strong correlation, R('2) = .996, was shown between reflectance values determined from satellite imagery and low-flying aircraft data. Of the 32 predicted reflectance values only six had a difference greater than 0.01. A mean difference of .0007 was obtained for the 32 cases. In addition, a procedure had to be developed to obtain uncorrected digital counts from processed satellite imagery.
11
Aksoy, Mustafa. "Radio Frequency Interference Characterization and Detection in L-band Microwave Radiometry." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448989873.
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12
Sorensen, Ira Joseph. "Analytical and Experimental Characterization of a Linear-Array Thermopile Scanning Radiometer for Geo-Synchronous Earth Radiation Budget Applications." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/35598.
Full textAbstract:
The Thermal Radiation Group, a laboratory in the department
of Mechanical Engineering at Virginia Polytechnic Institute and
State University, is currently working towards the development of
a new technology for cavity-based radiometers. The radiometer
consists of a 256-element linear-array thermopile detector
mounted on the wall of a mirrored wedge-shaped cavity.
The objective of this research is to provide analytical and
experimental characterization of the proposed radiometer. A
dynamic end-to-end opto-electrothermal model is developed to
simulate the performance of the radiometer. Experimental results
for prototype thermopile detectors are included. Also
presented is the concept of the discrete Green's function to
characterize the optical scattering of radiant energy in the
cavity, along with a data-processing algorithm to correct for the
scattering. Finally, a parametric study of the sensitivity of the discrete
Green's function to uncertainties in the surface properties of the
cavity is presented.Master of Science
13
Penny, Iain Reynold 1966. "Detector-based absolute radiometric calibration of lamps and reflectance panels." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277922.
Full textAbstract:
The absolute calibration of remote sensing systems is based upon radiometric standards. The irradiance standards are currently 1000-watt quartz tungsten-halogen lamps that are traced to National Institute of Standards and Technology standards by a middle party at a significant cost. Lamp instability, short lifetime and calibration inaccuracy present problems. A detector-based absolute calibration technique is described here to replace the lamp calibration in the visible portion of the spectrum (approximately 400 to 700 nm). The system utilizes a quantum efficient QED-200 trap detector in an automated facility to absolutely characterize lamp spectral irradiances or reflectance panel spectral radiances. The measured irradiance of a directly-viewed standard lamp compared favorably (within 0.8%) to the original calibration. Standard-reflectance-panel radiance measurements could not be accurately compared (within 5%) to the illuminating standard lamp irradiance because of excessive stray light in the calibration facility.
14
Joseph, Angelo Daniel. "Radiometric study of soil: the systematic effects." Thesis, University of the Western Cape, 2007. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6805_1248251582.
Full textAbstract:
The natural ²
³
â¸U, ²
³
²
Th and â´°
K radioactive content of vineyard soil was measured with an in-situ gamma-ray detector. The activity concentration measured with the in-situ detector are normalized using the laboratory-determined activity concentrations of several samples from the vineyard site. To determine the activity concentration of a particular soil sample, the gamma-ray photopeak detection efficiencies are required. In this work, the detection efficiencies were derived for each soil sample using gamma-ray photopeaks associated with the radionuclide of ²
³
â¸U, ²
³
²
Th present in the sample, and the â´°
K, 1460.8 keV gamma-ray peak, from KCl salt.
15
Ballew, Laura R. Jean B. Randall. "A microwave radiometer system for use in biomedical applications." Waco, Tex. : Baylor University, 2006. http://hdl.handle.net/2104/4956.
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16
Myers, Rebecca G. (Rebecca Gwen). "Potential for tsunami detection and early-warning using space-based passive microwave radiometry." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/42913.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 141-150).
The threat of a tsunami in coastal communities is considerable, especially in the Pacific and Indian Oceans. Current warning systems consist of two networks: (1) a network of seismometers, and (2) a network of sea level gauges and bottom pressure recorders. Bottom pressure recorders communicate with ocean surface buoys, which send the data to processing centers through satellite communication uplinks. The ability to quickly and accurately detect a tsunami in the deep ocean is proposed using a new space-based passive microwave radiometer system. Passive microwave radiometry can detect oceanic parameters such as sea-surface temperature and sea surface roughness to contribute to earlier tsunami detection, when the tsunami is farther from shore, which will increase the reaction time for at-risk coastal communities. This thesis will outline a physics based approach to manipulating brightness temperature data from the ocean's surface through the variation as a result of the satellite platform, the sensor, its location, the antenna, and other considerations. The thesis will give a description of how each component of the overall system will change the surface data because the observations are space-based. The thesis will also outline how the current detection system can be compared to the new space-based system. In the future, the comparison method can be used to make an argument to support the system with the best capability to serve as an efficient and accurate tsunami early-warning system.
by Rebecca G. Myers.
S.M.
17
Schuster, Michaela [Verfasser], Stefan [Akademischer Betreuer] Völker, Erkki [Gutachter] Ikonen, Armin [Gutachter] Sperling, and Adam [Gutachter] Wolisz. "Short-pulse lasers in photometry and radiometry : application of short-pulse lasers for the spectral calibration and characterisation of photometric and radiometric detectors / Michaela Schuster ; Gutachter: Erkki Ikonen, Armin Sperling, Adam Wolisz ; Betreuer: Stefan Völker." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156179807/34.
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Matthews, Grant. "Sensitivity of a geostationary satellite ERB radiometer to scene and detector non-uniformities." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405557.
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Melo, Arline Maria. "Radiometria com sensores de banda larga para a faixa THz." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260135.
Full textAbstract:
Orientadores : Edson Moschim, Pierre KaufmannDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica
20
Tarongí, Bauzá José Miguel. "Radio frequency interference in microwave radiometry: statistical analysis and study of techniques for detection and mitigation." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/117023.
Full textAbstract:
Microwave radiometry field has been increasing its performance with higher accuracy measurements, leading to a more
presence in the remote sensing field. Several space-borne, air-borne and ground-based radiometers have been developed to
perform measurement campaigns; however, the actual sensitivity of a radiometer is often limited by man-made radio emissions
such as radars, broadcasting emissions, wireless communications and many other communication systems based on
electromagnetic waves, limiting the improvement in the radiometers¿ performance. Consequently, in order to maintain the
accuracy in the radiometric measurements, it has been researched in the Radio Frequency Interference (RFI) detection and
mitigation systems and algorithms for the microwave radiometry field.
The scope of this doctoral thesis is the development and testing of RFI detection and mitigation algorithms in order to enhance
radiometric measurements performed by the Multifequency Experimental Radiometer with Interference Tracking for
Experiments over Land and Littoral (MERITXELL). The MERITXELL has been developed during this thesis with the idea
studying the RFI present in several radiometric bands and the way to mitigate it, as well as to obtain data from diverse
frequency bands and devices in only one measurement campaign.
21
Bazkir, Ozcan. "Realization Of Detector Based Spectral Responsivity Scale From Ultraviolet To Near Infrared Regions Of Electromagnetic Spectrum." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605148/index.pdf.
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Realization of spectral responsivity scale was studied in three stages. Firstly, absolute optical power measurements using Electrical Substitution Cryogenic Radiometer (ESCR) was studied. The absolute measurements were done at discrete laser wavelengths of tunable Ar+ (488 nm and 514.5 nm), Nd:YAG (532 nm) and fixed He-Ne (632.8 nm) laser sources. To increase measurement accuracy the method used for the stabilization of laser beams, transmittance measurements of optical windows, and minimization of scattered beams were discussed.
Secondly, realization of absolute responsivity scale between 350- 850 nm ranges was studied. The scale based on reflection type trap detectors consisting of three silicon photodiodes. Various measurement systems were established in order to make optical characterization of trap detectors like non-linearity, surface non-homogeneity, polarization dependency, reflectance, and internal quantum efficiency. The absolute responsivity was linked to the absolute optical power by measuring the current response of trap detectors to the absolute power measured by ESCR system at laser wavelengths. Using models for the trap detector&rsquos, reflectance and internal quantum efficiency the scale between 350- 850 nm ranges was realized with an uncertainty of 0.05 %. Finally, the spectral responsivity scale in ultraviolet (UV) and near-infrared (NIR) regions was realized using Electrically Calibrated Pyroelectric Radiometer (ECPR). Optically characterizing the spatial non-uniformity of pyroelectric detector and its surface reflectance, the spectral responsivity scale was established with uncertainties ±
0.5-1.0 % between 250 nm and 350 nm and ±
0.5-1.5 % between 850 and 2500 nm.
22
Collins, Thomas. "Characterisation of mycobacterium species using radiometric growth detection and thin-layer chromatography." Thesis, University of Ulster, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281212.
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Bodnar, Jean-Luc. "Radiometrie photothermique appliquee a la detection et a la caracterisation de fissures." Reims, 1993. http://www.theses.fr/1993REIMS020.
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Le but du present memoire est d'etudier les possibilites de la radiometrie photothermique pour la detection et la caracterisation de micro-fissures debouchantes ou non, dans des materiaux metalliques. Dans un premier temps, une approche des possibilites de la methode, mise en uvre sous excitation sinuoidale et detection synchrone, est realisee a l'aide de moyens disponibles au laboratoire. Un modele tridimensionnel permettant le calcul complet du signal photothermique est developpe. Les resultats theoriques et experimentaux obtenus montrent la faisabilite de la methode, mais aussi les limites du mode d'analyse utilise, beaucoup trop lent pour une inspection etendue des echantillons et peu adapte a la detection de defauts perpendiculaires a la surface. La seconde etape de l'etude consiste alors a concevoir et a realiser une nouvelle instrumentation permettant de surmonter les inconvenients precedents. Deux autres modes d'analyse sont envisages. Celui finalement retenu, met en uvre un balayage continu d'un faisceau focalise realise de facon synchrone avec le balayage ligne d'une camera de thermographie infrarouge. Un microscope est associe a la camera pour permettre d'obtenir un grandissement et une resolution optique suffisants. Divers types d'echantillons sont ensuite etudies, pour chacun d'eux, une confrontation avec la theorie est recherchee. Pour cela un modele bidimensionnel, permettant la aussi le calcul complet du signal photothermique, est developpe. Les resultats obtenus, montrent la possibilite de detecter, a des vitesses d'analyse elevees, divers types de fissures: debouchantes dans des echantillons a surface reflechissante ou non et non debouchantes. Ces resultats font aussi apparaitre les parts respectives des influences optique et thermique dans la construction du signal photothermique. Enfin, une derniere etude vise a rendre quantitatifs les resultats experimentaux obtenus. Les deformations du signal photothermique induites par l'instrumentation sont prises en compte, et une procedure de mesure partielle des caracteristiques geometriques, largeur et profondeur, des fissures debouchantes est presentee
24
Shahriar, Chowdhury. "Mitigation of Interference From Iridium Satellites by Parametric Estimation and Subtraction." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/36161.
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Radio astronomy is the science of observing the universe at radio frequencies. In recent years, radio astronomy has faced a growing interference problem as radio frequency (RF) bandwidth has become an increasingly scarce commodity. Communication systems such as Earth orbiting communication satellites creates severe interference to the radio telescopes. This thesis proposes an algorithm to mitigate the radio fre-
quency interference (RFI) from the Iridium satellite system. A technique is presented here to detect the downlink signal of Iridium, estimate the parameters of the signal, synthesize the noise-free version of the signal and finally subtract the recreated signal from the radio telescope output. Using both simulated and real data captured by a radio telescope testbed, we demonstrate that for Iridium bursts with 20 dB signal to noise power ratio (SNR), the proposed algorithm achieves more than 15 dB cancellation. The method proposed here can be implemented using present-day digital signal processing hardware and software. A performance analysis of this proposed cancellation scheme in the radio astronomy RFI mitigation regime is presented.Master of Science
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Mispan, Muhamad Radzali. "Multi-sensor remote sensing data for change detection analysis : a case study from peninsular Malaysia." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338538.
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Callahan, Karin E. "Validation of a Radiometric Normalization Procedure for Satellite-Derived Imagery Within a Change Detection Framework." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/6599.
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Detecting changes in land cover through time using remotely sensed imagery is a powerful application that has seen increased use as imagery has become more widely available and inexpensive. Before a time series of remotely sensed imagery can be used for change detection, images must first be standardized for effects outside of real surface change. This thesis established a validation protocol to evaluate the effectiveness of an automated technique for normalizing temporally separate but spatially coincident imagery. Using the concept of pseudo-invariant features between master-slave image pairs, spatially coincident dark and bright points are identified from images and a regression equation is calculated to normalize slave images to a master. I used two sets of imagery to test the performance of the standardization process, a spatially coincident, but temporally variable time series, and spatially and temporally variable images. I tested the underlying statistical assumptions of this approach, and performed simple image subtraction to validate the reduction of master-slave differences using invariant locations. In addition I tested the possibility of reducing between-sensor differences by applying simple linear regression to comparable bands of MSS and TM sensors.
Image subtraction showed decreases in master-slave differences as a result of the standardization process, and the process behaved appropriately when there should be no difference between master and slave images (adjacent, but temporally identical imagery). I also found that comparable bands between MSS and TM sensors are similar enough that linear regression may not significantly reduce between-sensor differences.
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Liao, Wen-Jiao. "Physics-based radiometric signature modeling and detection algorithms of land mines using electro-optical sensors." Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5num=osu1064252075.
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Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xxii, 255 p. : ill. (some col.). Advisors: Joel T. Johnson and Brian A. Baertlein, Dept. of Electrical Engineering. Includes bibliographical references (p. 247-255).
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Renzullo, Luigi John. "Radiometric processing of multitemporal sequences of satellite imagery for surface reflectance retrievals in change detection studies." Curtin University of Technology, Department of Applied Physics, 2004. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15737.
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A relative, lie-value image normalisation (LVIN) procedure was investigated as a means of estimating surface reflectances from sequences of Landsat TM and ETM+ imagery, and standardising image data for change detection studies when there are uncertainties in sensor calibration and atmospheric parameters over time. The basis of the LVIX procedure is that for an A-date sequence, the digital numbers (DNs) of N-1 overpass images can be mapped to the reflectance values of a reference image for a set of pseudo- invariant targets (PITs) common to all images in the sequence. The robust M-estimator was employed to provide the transformation function that achieved the mapping. The investigation also showed that in some instances the LVIN procedure could incorporate the modelled Path DN-the modelled DN for a target of zero surface reflectance. A lack of surface validation data was a limitation in the investigation. However, a qualitative evaluation of the LVIN procedure was possible by examining the pre- and post-normalisation image histograms. In a comparison with the results of the 6S radiative transfer code, it war observed that when both overpass and reference images were acquired with the same sensor, the LVIK procedure appeared t o correct for atmospheric effects; and when overpass and reference images were with different sensors, the LVIN procedure also corrected for between-sensor differences. Moreover, it was demonstrated for the more "temporally-invariant" PITs that the procedure retrieved surface reflectances that were on average within ±0.02 reflectance units.The ability of the LVIK procedure to standardise sequences of image data was further demonstrated in the study of vegetation change. The normalised difference vegetation index (NDVI) was calculated from LVIN estimates of surface reflectance for a selection of sites around the township of Mt. Barker, Western Australia. NDVI data had characteristics consistent with data that have been corrected for atmospheric effects. A modification to the LVIN procedure was also proposed based on an investigation of some empirically-derived vegetation reflectance relationships. Research into the robustness of the relationships for a greater range of vegetation types is recommended.
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BOUFFIES, SOPHIE. "Detection des nuages et quantification de la vapeur d'eau atmospherique avec le radiometre polder : preparation de la mission satellitaire." Paris 7, 1996. http://www.theses.fr/1996PA077021.
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Le radiometre polder (polarization and directionality of the earth's reflectances), place sur une orbite polaire heliosynchrone en aout 1996, effectuera des mesures spectrales, multidirectionnelles et polarisees du rayonnement solaire reflechi par le systeme terre-atmosphere. Pour la version satellitaire de polder la restitution des parametres geophysiques a partir des mesures sera faite quotidiennement a l'aide d'algorithmes prepares avant le lancement. Les missions scientifiques ont ete regroupees dans trois chaines de traitement: couleur de l'ocean, bilan radiatif et nuage, terres emergees. Notre travail se situe dans le cadre de la preparation des algorithmes terres emergees et porte plus precisement sur la detection des nuages d'une part et la quantification de la vapeur d'eau atmospherique d'autre part. Afin de mettre au point les differents tests nuageux, nous nous sommes bases sur des simulations de transfert radiatif, sur des mesures issues de la version aeroportee de polder et d'autres capteurs. La seconde partie de ce travail a pour objectif d'estimer le contenu en vapeur d'eau atmospherique a partir des mesures polder. S'appuyant sur des simulations de transfert radiatif, en conditions claires, une fonction reliant le rapport des reflectances au contenu en vapeur d'eau a ete developpee. Les incertitudes liees a differents parametres instrumentaux et geophysiques ont egalement ete estimees (de l'ordre de 10%). La methode a pu etre validee grace a des mesures issues de differentes campagnes aeroportees de polder
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Assice, Antoine. "Detection en ondes millimetriques de defauts dielectriques ou semi-conducteurs dans un materiau a pertes." Toulouse 3, 1987. http://www.theses.fr/1987TOU30182.
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Utilisation de la radiometrie en ondes millimetriques dans la recherche de discontinuites dielectriques dans les materiaux composites. Simulation en ondes millimetriques des variations de puissance qui existent entre la zone homogene et la zone contenant le defaut
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GIAROLA, RODRIGO S. "Estudo teórico-experimental da resposta radiométrica de câmaras de ionização utilizadas em dosimetria em feixes de raios X para diagnóstico radiológico." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11786.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Lopes, Tiago Neves. "VUV single photon gaseous photomultiplier with position capability." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11780.
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Mestrado em Engenharia FísicaA new position sensitive gas photomultiplier for the Vacuum Ultraviolet (VUV) region is presented in this work. The detector is composed by two THGEMs, followed by a 2D-THCOBRA being operated in Ne/CH4(5%), at 1 bar pressure in single photon mode. The 2D-THCOBRA is an hybrid microstructure which combines the robustness and the resistance to discharges of a THGEM with the two independent charge multiplication stages and the position discrimination of the 2D-MHSP. In this work the 2D-THCOBRA influence in the charge gain and IBF values was studied. The position resolution of the entire system was also studied. The achieved results shown a charge gain of 106 and, for this gain values, an IBF value of about 20%. Position resolutions below 300 μm were also obtained.
O presente trabalho baseia-se no desenvolvimento e estudo de um fotomultiplicador gasoso na região do Utra-Violeta de Vazio (UVV) e com capacidade de discriminação de posição. O detector é constituído por duas THGEM seguidas de uma 2D-THCOBRA, a operar em Ne/CH4(5%) à pressão de 1 bar e em modo de fotão único. A 2D-THCOBRA é uma estrutura híbrida, que resulta da combinação entre uma THGEM e uma 2D-MHSP, beneficiando da robustez e resistência às descargas da primeira e dos dois estágios de multiplicação e da capacidade de discriminação da posição da 2D-MHSP. Neste trabalho foi estudada a influência dos potenciais aplicados aos eléctrodos da 2D-THCOBRA no ganho e no refluxo de iões (IBF) do detector. Foi ainda avaliada a resolução em posição deste detector. Foram medidos ganhos da ordem de 106 e, para estes valores de ganho, IBF na ordem dos 20%. Obteve-se ainda resoluções em posição inferiores a 300 μm.
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Souza, César Salgado Vieira de. "Classify-normalize-classify : a novel data-driven framework for classifying forest pixels in remote sensing images." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/158390.
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O monitoramento do meio ambiente e suas mudanças requer a análise de uma grade quantidade de imagens muitas vezes coletadas por satélites. No entanto, variações nos sinais devido a mudanças nas condições atmosféricas frequentemente resultam num deslocamento da distribuição dos dados para diferentes locais e datas. Isso torna difícil a distinção dentre as várias classes de uma base de dados construída a partir de várias imagens. Neste trabalho introduzimos uma nova abordagem de classificação supervisionada, chamada Classifica-Normaliza-Classifica (CNC), para amenizar o problema de deslocamento dos dados. A proposta é implementada usando dois classificadores. O primeiro é treinado em imagens não normalizadas de refletância de topo de atmosfera para distinguir dentre pixels de uma classe de interesse (CDI) e pixels de outras categorias (e.g. floresta versus não-floresta). Dada uma nova imagem de teste, o primeiro classificador gera uma segmentação das regiões da CDI e então um vetor mediano é calculado para os valores espectrais dessas áreas. Então, esse vetor é subtraído de cada pixel da imagem e portanto fixa a distribuição de dados de diferentes imagens num mesmo referencial. Finalmente, o segundo classificador, que é treinado para minimizar o erro de classificação em imagens já centralizadas pela mediana, é aplicado na imagem de teste normalizada no segundo passo para produzir a segmentação binária final. A metodologia proposta foi testada para detectar desflorestamento em pares de imagens co-registradas da Landsat 8 OLI sobre a floresta Amazônica. Experimentos usando imagens multiespectrais de refletância de topo de atmosfera mostraram que a CNC obteve maior acurácia na detecção de desflorestamento do que classificadores aplicados em imagens de refletância de superfície fornecidas pelo United States Geological Survey. As acurácias do método proposto também se mostraram superiores às obtidas pelas máscaras de desflorestamento do programa PRODES.Monitoring natural environments and their changes over time requires the analysis of a large amount of image data, often collected by orbital remote sensing platforms. However, variations in the observed signals due to changing atmospheric conditions often result in a data distribution shift for different dates and locations making it difficult to discriminate between various classes in a dataset built from several images. This work introduces a novel supervised classification framework, called Classify-Normalize-Classify (CNC), to alleviate this data shift issue. The proposed scheme uses a two classifier approach. The first classifier is trained on non-normalized top-of-the-atmosphere reflectance samples to discriminate between pixels belonging to a class of interest (COI) and pixels from other categories (e.g. forest vs. non-forest). At test time, the estimated COI’s multivariate median signal, derived from the first classifier segmentation, is subtracted from the image and thus anchoring the data distribution from different images to the same reference. Then, a second classifier, pre-trained to minimize the classification error on COI median centered samples, is applied to the median-normalized test image to produce the final binary segmentation. The proposed methodology was tested to detect deforestation using bitemporal Landsat 8 OLI images over the Amazon rainforest. Experiments using top-of-the-atmosphere multispectral reflectance images showed that the deforestation was mapped by the CNC framework more accurately as compared to running a single classifier on surface reflectance images provided by the United States Geological Survey (USGS). Accuracies from the proposed framework also compared favorably with the benchmark masks of the PRODES program.
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Osunmadewa, Babatunde A., Christine Wessollek, and Pierre Karrasch. "Linear and segmented linear trend detection for vegetation cover using GIMMS normalized difference vegetation index data in semiarid regions of Nigeria." SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35266.
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Quantitative analysis of trends in vegetation cover, especially in Kogi state, Nigeria, where agriculture plays a major role in the region’s economy, is very important for detecting long-term changes in the phenological behavior of vegetation over time. This study employs the use of normalized difference vegetation index (NDVI) [global inventory modeling and mapping studies 3g (GIMMS)] data from 1983 to 2011 with detailed methodological and statistical approach for analyzing trends within the NDVI time series for four selected locations in Kogi state. Based on the results of a comprehensive study of seasonalities in the time series, the original signals are decomposed. Different linear regression models are applied and compared. In order to detect structural changes over time a detailed breakpoint analysis is performed. The quality of linear modeling is evaluated by means of statistical analyses of the residuals. Standard deviations of the regressions are between 0.015 and 0.021 with R2 of 0.22–0.64. Segmented linear regression modeling is performed for improvement and a decreasing standard deviation of 33%–40% (0.01–0.013) and R2 up to 0.82 are obtained. The approach used in this study demonstrates the added value of long-term time series analyses of vegetation cover for the assessment of agricultural and rural development in the Guinea savannah region of Kogi state, Nigeria.
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Khalaf, Ziad. "Contributions à l'étude de détection des bandes libres dans le contexte de la radio intelligente." Phd thesis, Supélec, 2013. http://tel.archives-ouvertes.fr/tel-00812666.
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Les systèmes de communications sans fil ne cessent de se multiplier pour devenir incontournables de nos jours. Cette croissance cause une augmentation de la demande des ressources spectrales, qui sont devenues de plus en plus rares. Afin de résoudre ce problème de pénurie de fréquences, Joseph Mitola III, en 2000, a introduit l'idée de l'allocation dynamique du spectre. Il définit ainsi le terme " Cognitive Radio " (Radio Intelligente), qui est largement pressenti pour être le prochain Big Bang dans les futures communications sans fil [1]. Dans le cadre de ce travail on s'intéresse à la problématique du spectrum sensing qui est la détection de présence des Utilisateurs Primaires dans un spectre sous licence, dans le contexte de la radio intelligente. L'objectif de ce travail est de proposer des méthodes de détection efficaces à faible complexité et/ou à faible temps d'observation et ceci en utilisant le minimum d'information a priori sur le signal à détecter. Dans la première partie on traite le problème de détection d'un signal aléatoire dans le bruit. Deux grandes méthodes de détection sont utilisées : la détection d'énergie ou radiomètre et la détection cyclostationnaire. Dans notre contexte, ces méthodes sont plus complémentaires que concurrentes. Nous proposons une architecture hybride de détection des bandes libres, qui combine la simplicité du radiomètre et la robustesse des détecteurs cyclostationnaires. Deux méthodes de détection sont proposées qui se basent sur cette même architecture. Grâce au caractère adaptatif de l'architecture, la détection évolue au cours du temps pour tendre vers la complexité du détecteur d'énergie avec des performances proches du détecteur cyclostationnaire ou du radiomètre selon la méthode utilisée et l'environnement de travail. Dans un second temps on exploite la propriété parcimonieuse de la Fonction d'Autocorrelation Cyclique (FAC) pour proposer un nouvel estimateur aveugle qui se base sur le compressed sensing afin d'estimer le Vecteur d'Autocorrelation Cyclique (VAC), qui est un vecteur particulier de la Fonction d'Autocorrelation Cyclique pour un délai fixe. On montre par simulation que ce nouvel estimateur donne de meilleures performances que celles obtenues avec l'estimateur classique, qui est non aveugle et ceci dans les mêmes conditions et en utilisant le même nombre d'échantillons. On utilise l'estimateur proposé, pour proposer deux détecteurs aveugles utilisant moins d'échantillons que nécessite le détecteur temporel de second ordre de [2] qui se base sur l'estimateur classique de la FAC. Le premier détecteur exploite uniquement la propriété de parcimonie du VAC tandis que le second détecteur exploite en plus de la parcimonie la propriété de symétrie du VAC, lui permettant ainsi d'obtenir de meilleures performances. Ces deux détecteurs outre qu'ils sont aveugles sont plus performants que le détecteur non aveugle de [2] dans le cas d'un faible nombre d'échantillons.
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De, Caluwe Nicolas. "Etude préliminaire sur les possibilités d'utilisation des images du capteur AVHRR des satellites atmosphériques de la NOAA pour la détection des zones brûlées dans les Ghâts occidentaux." Doctoral thesis, Universite Libre de Bruxelles, 2006. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210765.
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Moriya, Érika Akemi Saito [UNESP]. "Identificação de bandas espectrais para detecção de cultura de cana-de-açúcar sadia e doente utilizando câmara hiperespectral embarcada em VANT." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/133961.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A hipótese levantada neste trabalho foi que as imagens hiperespectrais tomadas de plataformas aéreas como o veículo aéreo não-tripulado (VANT) e assinaturas espectrais medidas em campo ou laboratório podem ser utilizados em Agricultura de Precisão, especificamente na identificação de doenças na lavoura de cana-de-açúcar. Para testar esta hipótese foi delineado um objetivo principal, desenvolver uma metodologia para realizar o tratamento e análise de imagens hiperespectrais obtidas por sensor aerotransportado, de modo que os produtos auxiliem na caracterização da resposta espectral da cana-de-açúcar visando a discriminação e reconhecimento de talhões com doença na cana-de-açúcar. Portanto, neste trabalho desenvolveu-se uma metodologia que envolveu a realização de levantamentos em campo apoiados radiometricamente e a realização de análises em laboratório, para obter a curva espectral de cana-de-açúcar sadia e doentes, no intuito de identificar os comprimentos de onda mais propícios para detecção de doenças. A identificação de comprimentos de onda sensíveis a mudanças pela ação de agentes patogênicos foi importante para a elaboração de índices para detecção de duas doenças da cana-de-açúcar (estria vermelha e mosaico). Além disso, foi analisada a influência do ângulo de visada na estimativa do fator de reflectância hemisférico cônico na cana-de-açúcar, verificando o efeito da anisotropia na cana-de-açúcar. A obtenção de informação sobre o efeito da anisotropia na cana-de-açúcar foi importante para definir a estratégia de processamento das imagens hiperespectrais. As regiões com cana-de-açúcar infectadas com estria vermelha e mosaico foram discriminadas a partir de imagens hiperespectrais adquiridas por VANT, proporcionando informação para o planejamento da aplicação de defensivos agrícolas com a determinação precisa do posicionamento das regiões contaminadas e definição das estratégias de manejo da cultura agrícola visando um melhor gerenciamento da produção.
The hypothesis in this study was that the hyperspectral images taken from aerial platforms like unmanned aerial vehicle (UAV) and spectral signatures measured in field or lab can be use in precision agriculture, specifically in identifying diseases in sugarcane crop. To test this hypothesis has been outlined a primary objective to develop a methodology to perform processing and analyzing hyperspectral images obtained by airborne sensor, so that the products assist in characterizing the spectral response of the sugarcane aiming discrimination and recognition stands with disease in sugarcane. Therefore, this study developed a methodology that involved surveying in supported radiometrically field and the analysis in the laboratory for the spectral curve of healthy and diseased sugarcane in order to identify the most propitious wavelengths to detect diseases. The identification of wavelengths sensitive to changes by the action of pathogens was important for the development of indexes to detect two diseases of sugarcane (red stripe and mosaic). Furthermore, was analyzed the influence of the viewing angle in estimating the hemispherical conical reflectance factor in sugarcane, by checking the effect of anisotropy in sugarcane. Obtaining information on the effect of anisotropy on sugarcane was important to define the hyperspectral image processing strategy. Regions with sugarcane infected with red stripe and mosaic were discriminated from hyperspectral images acquired by UAV, providing information for planning the application of agriculture defensives with the precise determination of the positioning of the contaminated regions and defining the management strategies of the crop to provide a better production management.
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Bouzaida, Dalel. "Caractérisation et suivi des états de surfaces éolisés en Tunisie pré-saharienne : approches stationnelle et spatiale." Thesis, Lyon 2, 2012. http://www.theses.fr/2012LYO20016.
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Suite aux changements climatiques, de nouveaux paysages reflétant les interactions entre les processus naturels et les activités humaines inappropriées sont apparus en Tunisie Méridionale. L’érosion éolienne en est l’une des manifestations les plus remarquables. Au cours de cette thèse, une méthodologie opérationnelle et validée (méthode du transect permanent) a été mise au point pour la caractérisation des états de surfaces éolisés et la quantification du bilan sédimentaire d’un transect d’environ 500m de longueur sur une période de deux ans. A l’échelle spatiale, la cartographie des Unités Eoliennes : zones de départ, transit et dépôt de sable a été élaborée. Un essai de caractérisation radiométrique des zones de dépôt ensablées a été ensuite tenté pour l’analyse diachronique des changements survenus durant plus de 35 ans. A l’échelle stationnelle, la méthode du transect permanent permet le calcul diachronique des bilans sédimentaires et la comparaison simultanée des changements des Complexes d’Etat de Surface. La seule observation des états de surface éolisés est insuffisante pour déterminer le fonctionnement éolien précis d’une région, elle induit à des erreurs d’interprétation sur les processus sédimentaires en cours.A l’échelle spatiale, les cartes des Unités Eoliennes permettent de déterminer la vulnérabilité du milieu face aux processus de déflation, transport et dépôt. De plus, la caractérisation des zones ensablées par des indices radiométriques n’est pas évidente avec des images de 30 m de résolution. Les analyses statistiques effectuées ont montré que l’indice de couleur est le plus indiqué pour ce genre d’étude. Le calcul des taux de changement entre deux images de dates successives permet d’estimer l’évolution temporelle des espaces ensablés et la distribution spatiale des zones nouvellement ensablées sur plus de 35 ansUnder the effect of climate change, new landscapes reflecting the interactions between natural processes and human inappropriate activities appeared in Southern Tunisia. Wind erosion is one of the most important events. In this thesis, operational and validated methodology (the permanent transect method) has been developed for the characterization of Surfaces States and quantification of the sediment balance of a 500 m length transect over a period of two years. On spatial scale, mapping of the Aeolian units of deflation, transit and sand deposit was developed. Radiometric characterization of sand accumulations was then tried for the detection of changes that occurred within more than 35 years.At the site level, the permanent transect method enabeled the diachronic sedimentary balance calculation and the comparison of the Surface states changes. The single observation of these areas is insufficient to determine the real eolian process of a region ; moreover it induces to errors of interpretation on the sedimentary process.At the spatial scale, maps of the Aeolian units enabeled to determine the vulnerability of the environment to the process of deflation, transport and deposition. In addition, the characterization of sand accumulations by radiometric indices is not obvious within 30 m resolution images. The statistical analyses have shown that Color Index is the most indicated for this type of study. The calculation of the rates of change between two successive dates images allows to estimate the sandy spaces evolution and their spatial distribution for more than 35 years
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SOHAIL, ARFAN. "Mapping Landcover/Landuse and Coastline Change in the Eastern Mekong Delta (Viet Nam) from 1989 to 2002 using Remote Sensing." Thesis, KTH, Samhällsplanering och miljö, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104189.
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There has been rapid change in the landcover/landuse in the Mekong delta, Viet Nam. The landcover/landuse has changed very fast due to intense population pressure, agriculture/aquaculture farming and timber collection in the coastal areas of the delta. The changing landuse pattern in the coastal areas of the delta is threatened to be flooded by sea level rise; sea level is expected to rise 33 cm until 2050; 45 cm until 2070 and 1 m until 2100. The coastline along the eastern Mekong delta has never been static, but the loss of mangrove forests along the coast has intensified coastline change. The objective of the present study is to map the changes in landcover/landuse along the eastern coast of the Mekong delta; and to detect the changes in position of the eastern coastline over the time period from 1989 to 2002.To detect changes in landuse, two satellite images of the same season, acquired by the TM sensor of Landsat 5 and the ETM+ sensor of Landsat 7 were used. The TM image was acquired on January 16, 1989 and ETM+ image was acquired on February 13, 2002. The landcover/landuse classes selected for the study are water, forest, open vegetation, soil and shrimp farms. Image differencing and post classification comparison are used to detect the changes between two time periods. Image to image correction technique is used to align satellite images. Maximum likelihood supervised classification technique is used to classify images. The result of the classification consists of five classes for 1989 and 2002, respectively. Overall accuracies of 87.5% and 86.8%, with kappa values of 0.85 and 0.84 are obtained for landuse 1989 and landuse 2002, respectively. The overall accuracy for the change map is 82% with kappa value 0.80. Post classification comparison is carried out in this study based on the supervised classification results. According to the results obtained from the post classification comparison, a significant decrease of 48% in forest and a significant increase of 74% in open vegetation and 21% in shrimp farms area observed over the entire study area. The coastline obtained by the combination of histogram thresholding and band ratio showed an overall advancement towards the South China Sea. The results showed that new land patches emerged along the eastern coast. The amount of new land patches appeared along the coast of the Mekong delta is approximately 2% of the entire study area.
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Nanzer, Jeffrey A. (Jeffrey Allan). "Human presence detection using millimeter-wave radiometry." Thesis, 2008. http://hdl.handle.net/2152/3961.
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A novel method of human presence detection using passive millimeter-wave sensors is presented. The method focuses on detecting a standing human from a moving platform in a cluttered outdoor environment using millimeter-wave radiometry, which has not been attempted before. Ka-band radiometers are used in total power mode as well as correlation mode, which ideally responds well to self-luminous objects such as humans. The intrinsic radiative power from a human is derived as well as the responses of the total power and correlation mode. The application of correlation radiometer theory to the detection of self-luminous objects at close range is presented in the context of human presence detection. Modifications and additions to techniques developed in radio astronomy and remote sensing for close range terrestrial situations are developed and discussed. The correlation radiometer fringe frequency is analyzed in the context of the scanning beam detection system and is estimated using MUSIC and ESPRIT. Detection and classification of humans is accomplished using a Naïve Bayesian classifier. The performance of the classifier is measured using the F1-measure and the receiver operating characteristic.text
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Yang, Zhiming. "Detection of greenbug infestation using ground-based radiometry." 2005. http://digital.library.okstate.edu/etd/umi-okstate-1361.pdf.
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Strabala, Kathleen I. "Optimum radiometric spectral intervals for cirrus detection." 1991. http://catalog.hathitrust.org/api/volumes/oclc/25376355.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1991.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 99-100).
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Goldin, Alexey. "Medium scale microwave background anisotropy : measurement and detectors design /." 1999. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9951787.
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Her, Pey-Yann, and 何珮艷. "The Effecct of Radiometric Normalization on SPOT Satellite Image Change Detection." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/45551477091513961824.
Full textAbstract:
碩士國立中興大學
森林學系
92
The rate of mountain area is over 50% in Taiwan. Landuse change monitoring has become important increasingly, because alpine vegetation is subject to environmental change. Change detection through satellite images may save much cost and labor, and digital images also facilitate processing and storage in a time?series database. However, radiometric difference introduced by atmosphere, illumination, sensor, and plant phenology may reduce the accuracy of change detection. The study was intended to confirm the importance of image normalization. It also eevaluated the performance of different image normalization methods in relation to change detection. Histogram matching (HM), linear regression normalization (LRN), and normalized difference vegetation index (NDVI) were applied to eight?date SPOT images in four seasons of 1994 and 1998 in Hohuan mountain area. The methods were compared in terms of their capability to improve visual image quality, statistical robustness, and ease of implementation. HM exhibited the best overall performance among them, NDVI was second to HM, and LRN was the last. Image normalization had better performance using visible bands than using near?infrared band. The performance had a tendency to increase with a smaller season difference between an image pair. Namely, an image pair acquired in the same season, particulary in summer, was better than one acquired in winter, the other in summer or vice versa. The key to a high or low accuracy in change detection was the errorneous assignment of no?change pixels to the likely?change or true?change pixels. Thus image normalization was of great important for change detection.
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Coetzee, Hendrik. "Acquisition, processing and enhancement of multi-channel radiometric data collected with ultralight aircraft mounted detectors." Thesis, 2008. http://hdl.handle.net/10539/5596.
Full textAbstract:
An ultralight aircraft based airborne geophysical system was developed and
operated by the Council for Geoscience during the period 1997-2004. The aim of
this project was to collect geophysical data at lower cost and higher resolution
than was possible using conventional airborne systems. This dissertation describes
the development of the radiometric systems used in the ultralight airborne survey
project. During the course of the study, a number of obstacles to the successful
collection and processing of radiometric data with the ultralight-mounted systems
were encountered. These are described and solutions proposed.
To facilitate the development hardware systems and processing methods, a Monte
Carlo simulation method was developed to produce spectra containing realistic
signal and noise components. This method was applied to the selection of detector
materials and the specification of detector sizes as well as being used to simulate
large spectral data sets for the development and testing of processing and
calibration procedures.
Radiometric data follow a Poisson Distribution, with the signal to noise ratio
being dependent on the count rate recorded, which, in turn, depends on the size of
the detector used. The ultralight aircraft were capable of carrying a detector one
eighth the size of that used in conventional systems. To allow for the use of the
smaller detector, the noise adjusted singular value decomposition (NASVD)
processing technique was employed. While this technique is commonly applied in
noise-reduction, the original application, namely the determination and mapping
of spectral components was also utilised.
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During the course of the study no suitable calibration facilities were available
inside South Africa. This necessitated the development of a spectral stripping
method, utilising a technique generally applied to much higher resolution spectral
data collected under laboratory conditions. Simulation studies and practical
application showed that this method performs well, in some cases outperforming
the conventional stripping method. The method is also applicable to the study of
anthropogenic radionuclides, where suitable calibration facilities are generally
unavailable. An alternative to the conventional method of altitude correction was
also applied to the radiometric data collected with the ultralight-mounted systems.
Using simulated data, a spectrometer based on a bismuth germanate (BGO)
detector was designed and constructed. This material is significantly denser than
the more usual thallium activated sodium iodide used for detector fabrication and
has a higher effective atomic number, giving it a greater photopeak efficiency.
However the poor light production of this scintillation material results in a poorer
energy resolution than a conventional detector. Initial tests using small BGO
detectors were promising and a larger detector was acquired and tested.
Unfortunately the poor energy resolution and high cost of BGO detectors led to
the conclusion that they did not offer the advantages initially hoped for.
Nevertheless a number of successful surveys were flown using the BGO detector.
Ultralight-mounted systems were found to be ideal for small surveys where high
spatial resolution is required. The ultralight systems were successfully applied to
the detection of radioactive pollution on a number of sites in the Witwatersrand
and related gold fields and one site where anthropogenic radionuclide
contamination was present. In some cases, the data could be compared to data
collected using a conventional airborne radiometric system. Here the ultralight-
mounted systems were found to perform satisfactorily, albeit with a poorer signal
to noise ratio except where adverse flying conditions necessitated flying at high
altitude.
The strengths, weaknesses and potential applications of ultralight-mounted
airborne radiometric systems are discussed.
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Zhang, Y., P. Lazaridis, Raed A. Abd-Alhameed, and Ian A. Glover. "A compact wideband printed antenna for free-space radiometric detection of partial discharge." 2016. http://hdl.handle.net/10454/8683.
Full textAbstract:
yesA microstrip line-fed wideband printed antenna is presented for radio detection of partial discharge (PD). The novel simple structure antenna has compact size of 24 × 20 × 0.16 cm3 (0.28λs × 0.23 λs × 0.002 λs) and suitable for radiometric PD wireless sensor nodes, where λs is the wavelength of the lowest frequency of the band (i.e., 0.35 GHz). The stepped and beveled radiation patch is used in combination with a slotted ground plane to achieve a wide fractional bandwidth of 119% (0.35 to 1.38 12 GHz) for a return loss better than 10 dB. Good radiation pattern characteristics are obtained across the frequency band of interest. The match between simulated and experimental results suggests that the design is sound and robust.
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Sobers, Tamara V. "The Measurement of Internal Temperature Anomalies in the Body Using Microwave Radiometry and Anatomical Information: Inference Methods and Error Models." 2012. https://scholarworks.umass.edu/theses/849.
Full textAbstract:
The ability to observe temperature variations inside the human body may help in detecting the presence of medical anomalies. Abnormal changes in physiological parameters (such as metabolic and blood perfusion rates) cause localized tissue temperature change. If the anatomical information of an observed tissue region is known, then a nominal temperature profile can be created using the nominal physiological parameters. Temperature-varying radiation emitted from the human body can be captured using microwave radiometry and compared to the expected radiation from nominal temperature profiles to detect anomalies. Microwave radiometry is a passive system with the ability to capture radiation from tissue up to several centimeters deep into the body. Our proposed method is to use microwave radiometry in conjunction with another imaging modality (such as ultrasound) that can provide the anatomical information needed to generate nominal profiles and improve detection of temperature anomalies. An inference framework is developed for using the nominal temperature profiles and radiometric weighting functions obtained from electromagnetic simulation software, to detect and estimate the location of temperature anomalies. The effects on inference performance of random and systematic deviations from nominal tissue parameter values in normal tissue are discussed and analyzed.
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Bo-YiLin and 林柏毅. "Radiometric Normalization and Cloud Detection of Multi-Temporal Optical Satellite Images Using Invariant Pixels." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/83073065723508883367.
Full textAbstract:
碩士國立成功大學
測量及空間資訊學系
102
Clouds in optical satellite images can be regarded as information for liquid water measurement or as contaminations that obstruct landscape observation. Thus, cloud detection that discriminates cloud and clear-sky pixels in images is a necessary processing step in remote sensing applications. With radiometric correction/normalization preprocessing, most previous studies utilized temporal and spectral information to develop thresholding-based filters with the aid of a cloud-free reference image. Although this strategy can efficiently and accurately identify cloud pixels, detection accuracy mainly relies on the success of radiometric correction/normalization and quality of the selected cloud-free reference image. Radiometric normalization generally suffers from cloud covers; cloud detection is sensitive to radiometric normalization. In this study, a method based on weighted invariant pixels is proposed for radiometric normalization and cloud detection. Utilizing temporal correlations, a set of invariant pixels obtained from the scatterplot of two adjacent images in time series through weighted principal component analysis are extracted from a time series of cloud-contaminated images with the reason that the variations of image digital counts during a period are linear. The image is normalized by using the selected invariant pixels with quality control or the so-called pseudo-invariant features. In addition, a composed cloud-free reference image is generated for each cloud-contaminated image by using the selected invariant pixels with a proposed weighting scheme. In the experiments, qualitative analyses of image sequences acquired by Landsat-7 Enhanced Thematic Mapper Plus (ETM+) sensor and quantitative analyses of image sequences with various cloud contamination conditions and landscapes are conducted to evaluate the proposed method. The experimental results show that the proposed radiometric normalization has the ability to deal with images that contain various clouds. Moreover, cloud detection accuracy is improved by 0.14% to 4.40% with the use of the generated reference images with a thresholding-based detection method.
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Pan, Li-Hui, and 潘麗慧. "Evaluation of the Effect of Relative Radiometric Normalization on Multi-date SPOT Image Change Detection." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/46814473328866128285.
Full textAbstract:
碩士國立中興大學
森林學系
92
Change detection from multi-temporal images has been commonly used in monitoring changes in landscape. However, spurious changes caused by variations of non-surface factors including illumination, viewing geometry, sensor calibration, and atmospheric effects, as well as surface factors including seasonal phonological differences and topographic effects, may lead to inaccurate results, thereby reducing the accuracy of landscape change detection. The study was intended to examine the influence of spectral variations caused by the non-surface factors and phonology on change detection and to confirm the importance of image normalization to change detection. The study also evaluated the performance of three image normalization methods in relation to change detection. Histogram matching (HM), image regression (IR), and pseudo-invariant feature (PIF) regression requiring the use of a reference-subject image pair, were applied to thirteen-date SPOT images from the Wu-Shyr-Keng area of Taichung Prefecture. Three images out of thirteen, acquired in summer, winter, and spring (or fall) were selected as a reference image, respectively. The methods were compared in terms of their capability to improve visual image quality, statistical robustness, and ease of implementation. The HM method was the first in overall performance, IR was the second, and PIF was the last. Image normalization had better performance using visible bands than using NDVI and near-infrared bands, and using red band slightly better than using green band. Low accuracies in change detection were primarily due to the erroneous assignment of no-change pixels to the likely-change class or true-change class. HM and IR improved accuracies effectively, but PIF performed unsteadily. On the other hand, the omission of true-change pixels is the key to change detection in spite of usually occupying a small proportion of the entire image. The three methods performed unsteadily, probably due to insufficient sample of true-change pixels, and further research shound be conducted in the future. The performance also tended to increase with a reduction in season difference between an image pair. An image pair acquired in the same season, particularly in summer, with time difference as short as possible is preferred, but one image of an image pair acquired in winter with the other in summer, or vice versa, should be avoided. Thus image normalization overall is of great importance for change detection.
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Jallad, Mahmoud 1979. "Performance of several diagnostic systems on detection of occlusal primary caries in permanent teeth." Thesis, 2014. http://hdl.handle.net/1805/6498.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)
Indiana University School of Dentistry Master Degree Thesis.Detection of caries at an early stage is unequivocally essential for early preventive intervention. Longitudinal assessment of caries lesions, especially under the opaque preventive sealant, would be of utmost importance to the dental community. OBJECTIVES: The aim of this two-part in-vitro study is to evaluate the performance of multiple detection methods: The International Caries Detection and Assessment System (ICDAS); two quantitative light-induced fluorescence systems QLF; Inspektor™ Pro and QLF-D Biluminator™2 (Inspektor Research Systems B.V.; Amsterdam, The Netherlands); and photothermal radiometry and modulated luminescence (PTR/LUM) of The Canary System® (Quantum Dental Technologies; Toronto, Canada). All these are to be evaluated on their detection of caries on posterior human permanent teeth for 1) of primary occlusal lesions, and 2) under the sealant of primary occlusal lesions. METHODS: One hundred and twenty (N = 120) human posterior permanent teeth, selected in compliance with IU-IRB “Institutional Review Board” standards, with non-cavitated occlusal lesions ICDAS (scores 0 to 4) were divided into two equal groups. The second group (N = 60) received an opaque resin dental sealant (Delton® Light-Curing Pit and Fissure Sealant Opaque, Dentsply, York, PA). All lesions were assessed with each detection method twice in a random order except for ICDAS, which was not used following the placement of the sealant. Histological validation was used to compare methods in regard to sensitivity, specificity, % correct, and the area under receiver- operating characteristic curve (AUC). Intra-examiner repeatability and inter-examiner agreement were measured using intraclass correlation coefficient (ICC). RESULTS: 1) Of primary occlusal lesions, sensitivity, specificity, and AUC values were respectively: 0.82, 0.86 and 0.87 (ICDAS); 0.89, 0.60 and 0.90 (Inspektor Pro); 0.96, 0.57 and 0.94 (QLF-D Biluminator 2); and 0.85, 0.43 and 0.79 (The Canary System). Intra-examiner repeatability and inter-examiner agreement were respectively: 0.81 to 0.87: 0.72 (ICDAS); 0.49 to 0.97: 0.73 (Inspektor Pro); 0.96 to 0.99: 0.96 (QLF-D Biluminator 2); and 0.33 to 0.63: 0.48 (The Canary System). 2) Of primary occlusal lesions under the opaque dental sealants, sensitivity, specificity, and AUC values were respectively: 0.99, 0.03 and 0.67 (Inspektor Pro); 1.00, 0.00 and 0.70 (QLF-D Biluminator 2); and 0.54, 0.50 and 0.58 (The Canary System). Intra-examiner repeatability and inter-examiner agreement were respectively: 0.24 to 0.37: 0.29 (Inspektor Pro); 0.80 to 0.84: 0.74 (QLF-D Biluminator 2); and 0.22 to 0.47: 0.01 (The Canary System). CONCLUSION: Limited to these in-vitro conditions, 1) ICDAS remains the method of choice for detection of early caries lesion due to its adequately high accuracy and repeatability. QLF systems demonstrate potential in longitudinal monitoring due to an almost perfect repeatability of QLF-D Biluminator 2. The Canary System performance and repeatability were not acceptable as a valid method of early caries detection. 2) None of the methods demonstrated acceptable ability in detecting of occlusal caries under the opaque sealant. However, QLF-D Biluminator 2, with limitation to these in-vitro conditions and Delton opaque sealant, demonstrated a fair accuracy AUC (0.70) in detecting of caries under sealants at an experimental threshold of 12.5% ΔF.