Dissertations / Theses: 'Calibration'

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Elkashef, Abdelaziz A. "Dry calibration milks for calibrating infrared milk analyzers." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59816.

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Calibration powders were developed using combinations of milk ingredients for the purpose of calibration of infrared milk analyzers. They were shown to be capable of producing calibrations very similar to conventional calibration milks available commercially. A subsequent collaborative study was carried out involving nine laboratories to assess the performance of the preformulated powders in industrial quality control, payment and dairy herd analysis laboratories. The calibration powders were shown to produce consistent calibrations within laboratories and between laboratories and met AOAC specifications in terms of accuracy and repeatability. The reconstituted solutions were shown to be stable for up to 6 h at 40$ sp circ$C and could be stored under refrigerated conditions and used for repeated analyses for up to 21 days without apparent deterioration in calibration performance. It was concluded that the calibration powders perform as well as conventional calibrants, were more consistent overall and suitable for any calibration application. The calibration powders have the stability and performance characteristics to serve as reference standards for monitoring instrument performance and would be a useful tool for accrediting payment and dairy herd analysis laboratories.

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Williams, Braydon J. "Uncertainty of Stereo PIV Calibration and Self-Calibration." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5263.

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Particle image velocimetry (PIV) is a widely used fluid measurement technique. Three dimensional PIV data or stereo PIV is acquired using two cameras. Stereo cameras are calibrated from camera coordinates, pixels, to real world units such as millimeters using calibration models. Stereo calibration is fundamental to the accuracy of a PIV measurement. In this thesis, the accuracy of the stereo calibration is assessed. The mean error of stereo calibration was found to be 0.23%.

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Schopp, Patrick [Verfasser], and Yiannos [Akademischer Betreuer] Manoli. "State estimation, calibration, and self-calibration for accelerometer arrays." Freiburg : Universität, 2018. http://d-nb.info/1166053725/34.

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Esquivel, Sandro [Verfasser]. "Eye-to-Eye Calibration - Extrinsic Calibration of Multi-Camera Systems Using Hand-Eye Calibration Methods / Sandro Esquivel." Kiel : Universitätsbibliothek Kiel, 2015. http://d-nb.info/1073150615/34.

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Zhang, Guoqiang. "Camera network calibration." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37011844.

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Wan, Shuang. "Parametric array calibration." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/4902.

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The subject of this thesis is the development of parametric methods for the calibration of array shape errors. Two physical scenarios are considered, the online calibration (self-calibration) using far-field sources and the offline calibration using near-field sources. The maximum likelihood (ML) estimators are employed to estimate the errors. However, the well-known computational complexity in objective function optimization for the ML estimators demands effective and efficient optimization algorithms. A novel space-alternating generalized expectation-maximization (SAGE)-based algorithm is developed to optimize the objective function of the conditional maximum likelihood (CML) estimator for the far-field online calibration. Through data augmentation, joint direction of arrival (DOA) estimation and array calibration can be carried out by a computationally simple search procedure. Numerical experiments show that the proposed method outperforms the existing method for closely located signal sources and is robust to large shape errors. In addition, the accuracy of the proposed procedure attains the Cram´er-Rao bound (CRB). A global optimization algorithm, particle swarm optimization (PSO) is employed to optimize the objective function of the unconditional maximum likelihood (UML) estimator for the farfield online calibration and the near-field offline calibration. A new technique, decaying diagonal loading (DDL) is proposed to enhance the performance of PSO at high signal-to-noise ratio (SNR) by dynamically lowering it, based on the counter-intuitive observation that the global optimum of the UML objective function is more prominent at lower SNR. Numerical simulations demonstrate that the UML estimator optimized by PSO with DDL is optimally accurate, robust to large shape errors, and free of the initialization problem. In addition, the DDL technique is applicable to a wide range of array processing problems where the UML estimator is employed and can be coupled with different global optimization algorithms.

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Alsam, Ali. "Optimising spectral calibration." Thesis, University of East Anglia, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405716.

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Spectral calibration is the problem of recovering colour device sensitivities (e. g. of a digital camera or scanner) given measured spectral data and the corresponding RGBs recorded by the device. Spectral calibration is useful because if we know how a color device responds to light then we can colourimetrically calibrate (map RGBs to perceptually relevant coordinates) using mathematical means. Unfortunately, spectral calibration is a hard problem. Device sensitivities are continuous functions of wavelength and so there are many degrees of freedom to be recover. This intrinsic high dimensional recovery problem is confounded by the fact that typical spectra colour signals are low dimensional. Specifically, though they are continuous functions of wavelength, the spectra can be parameterised by say 5 or 6 numbers. Spectral calibration then is an ill posed problem where we try to recover more parameters than we have degrees of freedom. One way to work with this ill posedness is to regularise the recovery (for example we might impose a constraint on the smoothness of the recovered sensor). This thesis makes 4 main contributions to spectral calibration. First, we undertake an in depth analysis of spectral calibration in general and regularisation techniques in particular. We show that existing approaches can be usefully combined to improve recovery performance. Second, we present a new and radically different approach to ill posedness. Rather than applying a constraint such as smoothness, we set forth methods to solve for all spectral sensitivities consistent with a given set of data (color signal spectra and corresponding RGBs). Given this feasible set, we show how we can calculate the most representative sensor and quantify its uncertainty. We can now evaluate the feasibility of regularised solutions and estimate their uncertainty. In the third part of this thesis we consider the practical hardness of spectral calibration. Measuring many colour signal spectra is a time consuming task and so we wondered how many colour signal spectra we had to measure to arrive at a good solution. Mathematical and experimental results show that spectral calibration, which previously involved 100s of measurements, can be replicated with just 6 or 7 spectra. Finally, we present a new method for estimating the support of a sensor (the part of the visible spectrum over which a sensor is sensitive) and incorporate this into our spectral calibration methods. This is shown to be a surprisingly powerful constrain for spectral calibration.

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Zhang, Guoqiang, and 張國強. "Camera network calibration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37011844.

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O'Kennedy, Brian James. "Stereo camera calibration." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53063.

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Thesis (MScEng)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: We present all the components needed for a fully-fledged stereo vision system, ranging from object detection through camera calibration to depth perception. We propose an efficient, automatic and practical method to calibrate cameras for use in 3D machine vision metrology. We develop an automated stereo calibration system that only requires a series of views of a manufactured calibration object in unknown positions. The system is tested against real and synthetic data, and we investigate the robustness of the proposed method compared to standard calibration practice. All the aspects of 3D stereo reconstruction is dealt with and we present the necessary algorithms to perform epipolar rectification on images as well as solving the correspondence and triangulation problems. It was found that the system performs well even in the presence of noise, and calibration is easy and requires no specialist knowledge.
AFRIKAANSE OPSOMMING: Ons beskryf al die komponente van 'n omvattende stereo visie sisteem. Die kern van die sisteem is 'n effektiewe, ge-outomatiseerde en praktiese metode om kameras te kalibreer vir gebruik in 3D rekenaarvisie. Ons ontwikkel 'n outomatiese, stereo kamerakalibrasie sisteem wat slegs 'n reeks beelde van 'n kalibrasie voorwerp in onbekende posisies vereis. Die sisteem word getoets met reële en sintetiese data, en ons vergelyk die robuustheid van die metode met die standaard algoritmes. Al die aspekte van die 3D stereo rekonstruksie word behandel en ons beskryf die nodige algoritmes om epipolêre rektifikasie op beelde te doen sowel as metodes om die korrespondensie- en diepte probleme op te los. Ons wys dat die sisteem goeie resultate lewer in die aanwesigheid van ruis en dat kamerakalibrasie outomaties kan geskied sonder dat enige spesialis kennis benodig word.

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Willerton, Marc. "Array auto-calibration." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11684.

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In this thesis, efficient methods are presented to calibrate large or small aperture array systems containing different types of uncertainties. specifically the challenge of reducing the number of external sources required to calibrate an array is addressed and array calibration methods suitable for use when sources may be operating in the "near-far" field of the array are developed. Together, this can ease the overheads involved in calibrating and recalibrating an array system. In addition to presenting novel array calibration algorithms, this thesis also presents a novel transformation allowing a planar array to be expressed as a virtual uniform linear array of a much larger number of elements. This allows the array manifold of a planar array, which in general consists of non-hyperhelical curves, to be expressed using a number of hyperhelices which each correspond to the array manifold of a linear array. This hyperhelical structure has the potential to ease calibration overheads as well as having many other potential applications in array processing. This thesis presents novel pilot and auto array calibration schemes for estimating different types of array uncertainties. A novel pilot calibration algorithm is proposed whereby a single source transmitting from a known location (i.e. a pilot) at two carrier frequencies is used to estimate geometrical uncertainties in a planar array. This is achieved by exploiting the frequency dependence on the boundary between the "near-far" and "far" field of the array. In addition, an auto-calibration method is presented which doesn't require any external sources to estimate array uncertainties. Here, geometrical, complex gain and local oscillator (i.e. frequency and phase) uncertainties associated with the array elements are considered. In this approach, array elements transmit in turn to the others which operate as an array receiver. Large and small array apertures are investigated. Throughout the thesis, extensive computer simulations are presented to analyse the performance of the algorithms developed.

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Osborne, Christine. "Non-parametric calibration." Thesis, University of Bath, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293248.

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Mostek, Nick. "Calibration system design and determination of filter calibration requirements for SNAP." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3278455.

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Thesis (Ph. D.)--Indiana University, Dept. of Astonomy, 2007.
Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6711. Adviser: Stuart Mufson. Title from dissertation home page (viewed May 20, 2008).

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Woschitz, Helmut [Verfasser]. "System Calibration of Digital Levels: Calibration Facility, Procedures and Results / Helmut Woschitz." Aachen : Shaker, 2003. http://d-nb.info/1170544592/34.

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Isoz, Wilhelm. "Calibration of Multispectral Sensors." Thesis, Linköping University, Department of Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5202.

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This thesis describes and evaluates a number of approaches and algorithms for nonuniform correction (NUC) and suppression of fixed pattern noise in a image sequence. The main task for this thesis work was to create a general NUC for infrared focal plane arrays. To create a radiometrically correct NUC, reference based methods using polynomial approximation are used instead of the more common scene based methods which creates a cosmetic NUC.

The pixels that can not be adjusted to give a correct value for the incomming radiation are defined as dead. Four separate methods of identifying dead pixels are used to find these pixels. Both the scene sequence and calibration data are used in these identifying methods.

The algorithms and methods have all been tested by using real image sequences. A graphical user interface using the presented algorithms has been created in Matlab to simplify the correction of image sequences. An implementation to convert the corrected values from the images to radiance and temperature is also performed.

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Roy, Sébastien. "Calibration, rectification et stéréoscopie." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0015/NQ47640.pdf.

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Zhang, Hui. "Camera calibration from silhouettes." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37743752.

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Wülfert, Florian. "Temperature-robust multivariate calibration." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/76379.

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Tang, Zhongwei. "High precision camera calibration." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2011. http://tel.archives-ouvertes.fr/tel-00675484.

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The thesis focuses on precision aspects of 3D reconstruction with a particular emphasis on camera distortion correction. The causes of imprecisions in stereoscopy can be found at any step of the chain. The imprecision caused in a certain step will make useless the precision gained in the previous steps, then be propagated, amplified or mixed with errors in the following steps, finally leading to an imprecise 3D reconstruction. It seems impossible to directly improve the overall precision of a reconstruction chain leading to final imprecise 3D data. The appropriate approach to obtain a precise 3D model is to study the precision of every component. A maximal attention is paid to the camera calibration for three reasons. First, it is often the first component in the chain. Second, it is by itself already a complicated system containing many unknown parameters. Third, the intrinsic parameters of a camera only need to be calibrated once, depending on the camera configuration (and at constant temperature). The camera calibration problem is supposed to have been solved since years. Nevertheless, calibration methods and models that were valid for past precision requirements are becoming unsatisfying for new digital cameras permitting a higher precision. In our experiments, we regularly observed that current global camera methods can leave behind a residual distortion error as big as one pixel, which can lead to distorted reconstructed scenes. We propose two methods in the thesis to correct the distortion with a far higher precision. With an objective evaluation tool, it will be shown that the finally achievable correction precision is about 0.02 pixels. This value measures the average deviation of an observed straight line crossing the image domain from its perfectly straight regression line. High precision is also needed or desired for other image processing tasks crucial in 3D, like image registration. In contrast to the advance in the invariance of feature detectors, the matching precision has not been studied carefully. We analyze the SIFT method (Scale-invariant feature transform) and evaluate its matching precision. It will be shown that by some simple modifications in the SIFT scale space, the matching precision can be improved to be about 0.05 pixels on synthetic tests. A more realistic algorithm is also proposed to increase the registration precision for two real images when it is assumed that their transformation is locally smooth. A multiple-image denoising method, called ''burst denoising'', is proposed to take advantage of precise image registration to estimate and remove the noise at the same time. This method produces an accurate noise curve, which can be used to guide the denoising by the simple averaging and classic block matching method. ''burst denoising'' is particularly powerful to recover fine non-periodic textured part in images, even compared to the best state of the art denoising method.

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程貞如 and Ching-yu Ching. "Calibration of examination marks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31211318.

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Zhang, Hui, and 張慧. "Camera calibration from silhouettes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37743752.

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Denham, Michael Charles. "Calibration in infrared spectroscopy." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316562.

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Blomé, Tobias, and Adam Törnqvist. "Intraday Volatility Surface Calibration." Thesis, Umeå universitet, Institutionen för matematik och matematisk statistik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-172619.

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On the financial markets, investors search to achieve their economical goals while simultaneously being exposed to minimal risk. Volatility surfaces are used for estimating options' implied volatilities and corresponding option prices, which are used for various risk calculations. Currently, volatility surfaces are constructed based on yesterday's market information and are used for estimating options' implied volatilities today. Such a construction gets redundant very fast during periods of high volatility, which leads to inaccurate risk calculations. With an aim to reduce volatility surfaces' estimation errors, this thesis explores the possibilities of calibrating volatility surfaces intraday using incomplete market information. Through statistical analysis of the volatility surfaces' historical movements, characteristics are identified showing sections with resembling motion patterns. These insights are used to adjust the volatility surfaces intraday. The results of this thesis show that calibrating the volatility surfaces intraday can reduce the estimation errors significantly during periods of both high and low volatility. However, these results highly depend on the conducted choices when constructing and analyzing the volatility surfaces which leave room for further reasearch.

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Van, der Horn Gert. "Integrated smart sensors calibration." Delft, Netherlands : Delft University Press, 1997. http://books.google.com/books?id=tHhRAAAAMAAJ.

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Ghassemian, Alireza. "Robust remote measurement calibration." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-03242009-040805/.

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Ching, Ching-yu. "Calibration of examination marks /." [Hong Kong] : University of Hong Kong, 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1364533X.

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Scott, Karen Patricia 1964. "Radiometric calibration of on-orbit satellite sensors using an improved cross-calibration method." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282831.

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As the field of remote sensing continues to grow with the launches of many new and complex satellite sensors in the next year, the ability to provide absolute calibration of these sensors becomes paramount for the many environmental studies proposed. In particular, temporal studies that monitor global changes in atmospheric constituents, ocean and terrestrial temperatures, and vegetation require that changes in the sensor itself, over the period of the study, be understood so that the data may be corrected. Numerous studies have established that satellite sensors change in orbit with respect to preflight calibration, in some cases, up to 20% or more over periods of three years. This research describes the development of an improved cross-calibration method of on-orbit satellite sensor radiometric calibration. The objective of the cross-calibration method is to transfer one sensor's calibration to another sensor which is typically difficult or expensive to calibrate with other methods. The cross-calibration method is relatively inexpensive to apply, and therefore there was a strong incentive to improve the application of the method and the understanding of the uncertainties associated with the method. The primary effort in this work has been the development of a cross-calibration software program which provides the means to easily perform end-to-end cross-calibrations. The program allows for a multiplicity of sites to be run, provides a search mechanism in order to identify calibration sites with particular characteristics, and contains an extensive error analysis capability. As part of this work, a search for acceptable cross-calibration sites was also performed which would allow a reduction in uncertainties of the method. Calibrations of five different sensor band pairs using System Pour l'Observation de la Terre (SPOT) 3, Landsat Thematic Mapper, and Advanced Very High Resolution Radiometer (AVHRR) sensors are performed. Very good results are obtained when the results are compared with other more expensive calibration methods, and the calibrations yielded uncertainties lower than reported in previous work.

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Kümmerle, Julius Valentin [Verfasser], and C. [Akademischer Betreuer] Stiller. "Multimodal Sensor Calibration with a Spherical Calibration Target / Julius Valentin Kümmerle ; Betreuer: C. Stiller." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1220359092/34.

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Kümmerle, Julius [Verfasser], and C. [Akademischer Betreuer] Stiller. "Multimodal Sensor Calibration with a Spherical Calibration Target / Julius Valentin Kümmerle ; Betreuer: C. Stiller." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1220359092/34.

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Tsivras, Sotirios-Ilias. "ALTO Timing Calibration : Calibration of the ALTO detector array based on cosmic-ray simulations." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-79429.

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This thesis describes a timing calibration method for the detector array of the ALTO experiment. ALTO is a project currently at the prototype phase that aims to build a gamma-ray astronomical observatory at high-altitude in the Southern hemisphere. ALTO can be assumed as a hybrid system as each detector consists of a Water Cherenkov Detector (WCD) on top of a Scintillator Detector (SD), providing an increased signal to background discrimination compared to other WCD arrays. ALTO is planned to complement the Very-High-Energy (VHE) observations by the High Altitude Water Cherenkov (HAWC) gamma ray observatory that collects data from the Northern sky. By the time the full array of 1242 detectors is installed to the proposed site, ALTO together with HAWC and the future Cherenkov Telescope Array (CTA) will serve as a state-of-the-art detection system for VHE gamma-rays combining the WCD and the Imaging Atmospheric Cherenkov Telescope (IACT) techniques. When a VHE gamma-ray or cosmic-ray enters the Earth’s atmosphere, it initiates an Extensive Air Shower (EAS). These particles are sampled by the detector array and by checking the arrival times of nearby tanks, the method reveals whether a detector suffers from a time-offset. The data analyzed in this thesis derive from CORSIKA (COsmic Ray SImulation for KAscade) and GEANT4 (GEometry ANd Tracking) simulations of cosmic-ray events within the energy range of 1–1:6TeV, which mainly consist of protons. The high flux of this particular type of cosmic-rays, gives us a tool to statistically evaluate the results generated by the proposed timing calibration method. In the framework of this thesis, I have written code in Python programming language in order to develop the timing calibration method. The method identifies detectors that suffer from time-offsets and improves the reconstruction accuracy of the ALTO detector array. Different Python packages were used to execute different tasks: astropy to read filter-present-write large datasets, numpy (Numerical Python) to make datasets comprehensiveto functions, scipy (Scientific Python) to develop our models, sympy (Symbolic Python) to find geometrical correlations and matplotlib (Mathematical Plotting Library) to draw figures and diagrams. The current version of the method achieves sub-nanosecond accuracy. The next stepis to make the timing calibration more intelligent in order to correct itself. This self correction includes an agile adaptation to the data acquired for long periods of time, in order to make different compromises at different time intervals.

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Grahn, Karl-Johan. "ATLAS Calorimetry : Hadronic Calibration Studies." Licentiate thesis, KTH, Physics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9423.

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The ATLAS experiment -- situated at the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva -- is on schedule to take its first collision data in 2009. Physics topics include finding the Higgs boson, heavy quark physics, and looking for extensions of the standard model such as supersymmetry. Upon acceptance of an event by the level 1 trigger, data is read out from the liquid argon calorimeters using multi-mode optical fibers. In total, 58 cables were installed, corresponding to 232 12-fiber ribbons or 2784 individual fibers. The cables, about one hundred meters in length, were installed between the main ATLAS cavern and the counting room in the USA15 cavern. Patch cables were spliced onto the ribbons and the fiber attenuation was measured. For 1296 fiber pairs in 54 cables, the average attenuation was 0.69 dB. Only five fibers were found to have losses exceeding 4 dB, resulting in a failure rate of less than 2 per mil. In the ATLAS liquid argon barrel presampler, short circuits consisting of small pieces of dust, metal, etc. can be burned away in situ by discharging a capacitor over the high voltage lines. In a burning campaign in November 2006, seventeen existing short circuits were successfully removed. An investigation on how to implement saturation effects in liquid argon due to high ionization densities resulted into the implementation of the effect in the ATLAS Monte Carlo code, improving agreement with beam test data. The timing structure of hadronic showers was investigated using a Geant4 Monte Carlo. The expected behavior as described in the literature was reproduced, with the exception that some sets of physics models gave unphysical gamma energies from nuclear neutron capture. An ATLAS Combined Beam Test was conducted in the summer/fall of 2004 in the CERN H8 area, containing a whole slice of the ATLAS detectors in the central barrel region. The controlled single-particle environment allows the validation of Monte Carlo code and calibration. A method for calibrating the response of a segmented calorimeter to hadrons was developed. The ansatz is that information on longitudinal shower fluctuations gained from a principal component analysis of the layer energy depositions can improve energy resolution by correcting for hadronic invisible energy and dead material losses: projections along the eigenvectors of the correlation matrix are used as input for the calibration. The technique was used to reconstruct the energy of pions impinging on the ATLAS calorimeters during the 2004 Combined Beam Test. Simulated Monte Carlo events were used to derive corrections for invisible energy lost in nuclear reactions and in dead material in front and in between the calorimeters. For pion beams with energies between 20 and 180 GeV, the particle energy was reconstructed within 3% and the resolution was improved by about 20%. As a comparison, a simple iterative scheme with a single e/π factor and dead material corrections was devised, giving similar performance.

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Aykanat, Buket. "Calibration Of Uniform Circular Arrays." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612516/index.pdf.

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In practice, there exist many error sources which distort the antenna array pattern. For example, elements of antenna arrays influence each other (known as mutual coupling), mismatches in cables and element positions affects the antenna radiation pattern and also unequal gain and phase characteristics of RF receiver distorts the received signal. These effects generally degrade the array performance. They cause an increase in sidelobe levels with an accompanying decrease in gain. Also, these errors limit the performance of direction finding (DF) algorithms. So, in order to have low sidelobe level, good performance in direction finding and beamforming, calibration is necessary. In the literature, there exist many algorithms proposed for the calibration of errors. Calibration method used in this thesis assumes that there is a linear transformation between ideal signal and measurements. Calibration matrix is formed by using measurements. In this work, we look for the adequate number of measurements for successful calibration. Performance of calibration method may depend on the angle interval from which measurements are taken. So, the width of the data collection angle interval is also studied. Moreover, in real life, measurements can be collected from equally or randomly spaced angles. Does it affect the performance of calibration? The answer of this question is also inspected in this thesis. Additionally, the performance of algorithm under noise is studied. Performance evaluation is done for both elevation and azimuth sectors. Simulations are carried out on MATLABTM and Ansoft HFSS software package.

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Ar, Kerem. "Calibration Of Water Distribution Networks." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12613934/index.pdf.

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Water distribution network models are used for different purposes. In this study, a model, used for daily operational issues is concerned. Models results should be consistent with actual conditions for sound decisions during operational studies. Adjusting model parameters according to site measurements in order to fit the model to obtain realistic results is known as calibration. Researchers have carried out numerous studies on calibration and developed various methods. In this study, an actual network (N8.3 Pressure Zone, Ankara) has been calibrated by two classical methods developed by Walski (1983) and Bhave (1988). The network parameter calibrated in this study is Hazen-Williams roughness coefficient, C-factor, and other parameters have been lumped in the C-factor. Results of the analysis showed that, C-factors have been found in a wide range.

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Kassaye, Meseret Haile, and Yigit Demir. "Calibration Based On Principal Components." Thesis, Örebro universitet, Handelshögskolan vid Örebro Universitet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-26582.

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This study is concerned in reducing high dimensionality problem of auxiliary variables in the calibration estimation with the presence of nonresponse. The calibration estimation is a weighting method assists to compensate for the nonresponse in the survey analysis. Calibration estimation using principal components (PCs) is new idea in the literatures. Principal component analysis (PCA) is used in reduction dimension of the auxiliary variables. PCA in calibration estimation is presented as an alternative method for choosing the auxiliary variables. In this study, simulation on the real data is used and nonresponse mechanism is applied on the sampled data. The calibration estimator is compared using different criteria such as varying the nonresponse rate and increasing the sample size. From the results, although the calibration estimation based on the principal components have reasonable outputs to use instead of the whole auxiliary variables for the means, the variance is very large compared with based on original auxiliary variables. Finally, we identified the principal component analysis is not efficient in the reduction of high dimensionality problem of auxiliary variables in the calibration estimation for large sample sizes.

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Bednjanec, Martina. "Calibration of ALS Intensity Data." Thesis, KTH, Geoinformatik och Geodesi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-38998.

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With general advancements in computer technology and development ofdirect geo-referencing technology, such as GPS, airborne laser scanningsystems came into widespread use especially after 2002. In spite of relativelyhigh cost of purchase, the systems proved to be cost effective, providing fastand in large volumes 3D geospatial data acquisition with unprecedentedaccuracy and relatively modest processing complexity. Country-widecollection of laser scanning data, mainly due to DTM derivation, is becomingan attractive possibility for mapping. Since 2009, Swedish Government hasapproved and financed the project of developing the New National ElevationModel (NNH) for the country of Sweden, with aspects of monitoring climatechanges and other environmental impacts. The National Land Survey ofSweden, which is commissioned to carry out the project, is offering this highlyaccurate scanned data less expensive to secondary users, such as companiesspecialized in forestry applications, etc. Beside the geospatial data (X, Y, Z),laser systems additionally record the received signal intensity for eachmeasurement. So far, intensity values were just an additional variable, notused extensively, but in recent years many efforts have been made tounderstand and interpret these values. The wider use of intensity data ismissing due to the lack of techniques to calibrate them, so that theyrepresent values proportional to the scattering characteristics of the target. Inthe scope of this thesis it was examined which properties influence intensityvalues and to what degree. Already proposed methods for calibration weresummarized and the most suitable one was implemented based on the datafrom the NNH project and instruments used for it. The results proved to begood both empirically and visually, with reduced intensity variations over thesame targets. The potentials of using this corrected data are presented, suchas surface classification, automatic object recognition, multi-temporalanalysis, and more.

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Hand, Karen Joan. "Confidence regions in multivariate calibration." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35797.pdf.

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Andersson, Greger. "Novel nonlinear multivariate calibration methods /." Stockholm : Tekniska högsk, 1998. http://www.lib.kth.se/abs98/ande0528.pdf.

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Lu, Bing. "Calibration, Optimality and Financial Mathematics." Doctoral thesis, Uppsala universitet, Matematiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-209235.

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This thesis consists of a summary and five papers, dealing with financial applications of optimal stopping, optimal control and volatility. In Paper I, we present a method to recover a time-independent piecewise constant volatility from a finite set of perpetual American put option prices. In Paper II, we study the optimal liquidation problem under the assumption that the asset price follows a geometric Brownian motion with unknown drift, which takes one of two given values. The optimal strategy is to liquidate the first time the asset price falls below a monotonically increasing, continuous time-dependent boundary. In Paper III, we investigate the optimal liquidation problem under the assumption that the asset price follows a jump-diffusion with unknown intensity, which takes one of two given values. The best liquidation strategy is to sell the asset the first time the jump process falls below or goes above a monotone time-dependent boundary. Paper IV treats the optimal dividend problem in a model allowing for positive jumps of the underlying firm value. The optimal dividend strategy is of barrier type, i.e. to pay out all surplus above a certain level as dividends, and then pay nothing as long as the firm value is below this level. Finally, in Paper V it is shown that a necessary and sufficient condition for the explosion of implied volatility near expiry in exponential Lévy models is the existence of jumps towards the strike price in the underlying process.

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Armstrong, Martin Neil. "Self-calibration from image sequences." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337557.

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Hsu, P. W. "Freehand three- dimensional ultrasound calibration." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604687.

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In this thesis, we investigate how to achieve an accurate reliable and rapid probe calibration. Our first step is to improve the reliability of an accurate calibration technique from the literature. The Cambridge phantom, a variant of plane-based calibration, has been shown to be one of the most accurate calibration techniques. Unfortunately, calibrations performed using plane-based techniques are often unreliable. We show how it is possible to provide feedback on the reliability of the calibration. This allows the user to rectify an unreliable calibration. Having achieved an accurate and reliable calibration, we now search for a fast and easy calibration technique. We study a class of two-dimensional alignment phantoms – the Z-fiducial phantom. Probe calibration using such a phantom only requires a single image of the phantom. However, calibration speed using this phantom is impeded by the necessity of segmenting isolated points on the phantom reliably, which requires human intervention. We solve this problem by mounting a thin rubber membrane on top of the phantom. The membrane is segmented automatically and the phantom features can be easily located. This enables us to segment isolated points automatically at the full PAL frame rate of 25Hz, enabling calibration to be completed in a few seconds. In addition, to improve the existing calibration techniques, we present two novel phantoms – the cone phantom and the Cambridge stylus. They are both simple in design, easy to use and produce accurate calibrations. The cone phantom produces calibrations with accuracies matching the Cambridge phantom. The Cambridge stylus is small in size and can be carried around conveniently. These phantoms offer alternatives to the Cambridge phantom and the Z-phantom, ensuring calibration reliability and simplicity, while producing accurate calibrations.

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Kovachev, Yavor. "Calibration of stochastic volatility models." Thesis, Uppsala universitet, Analys och sannolikhetsteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227502.

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Hong, Liang. "INTER-SATELLITE MICROWAVE RADIOMETER CALIBRATION." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3323.

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The removal of systematic brightness temperature (Tb) biases is necessary when producing decadal passive microwave data sets for weather and climate research. It is crucial to achieve Tb measurement consistency among all satellites in a constellation as well as to maintain sustained calibration accuracy over the lifetime of each satellite sensor. In-orbit inter-satellite radiometric calibration techniques provide a long term, group-wise solution; however, since radiometers operate at different frequencies and viewing angles, Tb normalizations are made before making intermediate comparisons of their near-simultaneous measurements. In this dissertation, a new approach is investigated to perform these normalizations from one satellite's measurements to another. It uses Taylor's series expansion around a source frequency to predict Tb of a desired frequency. The relationship between Tb's and frequencies are derived from simulations using an oceanic Radiative Transfer Model (RTM) over a wide variety of environmental conditions. The original RTM is built on oceanic radiative transfer theory. Refinements are made to the model by modifying and tuning algorithms for calculating sea surface emission, atmospheric emission and attenuations. Validations were performed with collocated WindSat measurements. This radiometric calibration approach is applied to establish an absolute brightness temperature reference using near-simultaneous pair-wise comparisons between a non-sun synchronous radiometer and two sun-synchronous polar-orbiting radiometers: the Tropical Rain Measurement Mission (TRMM) Microwave Imager (TMI), WindSat (on Coriolis) and Advanced Microwave Scanning Radiometer (AMSR) on Advanced Earth Observing System –II (ADEOSII), respectively. Collocated measurements between WindSat and TMI as well as between AMSR and TMI, within selected 10 weeks in 2003 for each pair, are collected, filtered and applied in the cross calibration. AMSR is calibrated to WindSat using TMI as a transfer standard. Accuracy prediction and error source analysis are discussed along with calibration results. This inter-satellite radiometric calibration approach provides technical support for NASA's Global Precipitation Mission which relies on a constellation of cooperative satellites with a variety of microwave radiometers to make global rainfall measurements.
Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD

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Lindholm, Love. "Calibration and Hedging in Finance." Licentiate thesis, KTH, Numerisk analys, NA, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156077.

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This thesis treats aspects of two fundamental problems in applied financial mathematics: calibration of a given stochastic process to observed marketprices on financial instruments (which is the topic of the first paper) and strategies for hedging options in financial markets that are possibly incomplete (which is the topic of the second paper). Calibration in finance means choosing the parameters in a stochastic process so as to make the prices on financial instruments generated by the process replicate observed market prices. We deal with the so called local volatility model which is one of the most widely used models in option pricing across all asset classes. The calibration of a local volatility surface to option marketprices is an ill-posed inverse problem as a result of the relatively small number of observable market prices and the unsmooth nature of these prices in strike and maturity. We adopt the practice advanced by some authors to formulate this inverse problem as a least squares optimization under the constraint that option prices follow Dupire’s partial differential equation. We develop two algorithms for performing the optimization: one based on techniques from optimal control theory and another in which a numerical quasi-Newton algorithmis directly applied to the objective function. Regularization of the problem enters easily in both problem formulations. The methods are tested on three months of daily option market quotes on two major equity indices.The resulting local volatility surfaces from both methods yield excellent replications of the observed market prices. Hedging is the practice of offsetting the risk in a financial instrument by taking positions in one or several other tradable assets. Quadratic hedging is a well developed theory for hedging contingent claims in incomplete markets by minimizing the replication error in a suitable L2-norm. This theory, though, is not widely used among market practitioners and relatively few scientific papers evaluate how well quadratic hedging works on real marketdata. We construct a framework for comparing hedging strategies, and use it to empirically test the performance of quadratic hedging of European call options on the Euro Stoxx 50 index modeled with an affine stochastic volatility model with and without jumps. As comparison, we use hedging in the standard Black-Scholes model. We show that quadratic hedging strategies significantly outperform hedging in the Black-Scholes model for out of the money options and options near the money of short maturity when only spot is used in the hedge. When in addition another option is used for hedging, quadratic hedging outperforms Black-Scholes hedging also for medium dated options near the money.
Den här avhandlingen behandlar aspekter av två fundamentala problem i tillämpad finansiell matematik: kalibrering av en given stokastisk process till observerade marknadspriser på finansiella instrument (vilket är ämnet för den första artikeln) och strategier för hedging av optioner i finansiella marknader som är inkompletta (vilket är ämnet för den andra artikeln). Kalibrering i finans innebär att välja parametrarna i en stokastisk process så att de priser på finansiella instrument som processen genererar replikerar observerade marknadspriser. Vi behandlar den så kallade lokala volatilitets modellen som är en av de mest utbrett använda modellerna inom options prissättning för alla tillgångsklasser. Kalibrering av en lokal volatilitetsyta till marknadspriser på optioner är ett illa ställt inverst problem som en följd av att antalet observerbara marknadspriser är relativt litet och att priserna inte är släta i lösenpris och löptid. Liksom i vissa tidigare publikationer formulerar vi detta inversa problem som en minsta kvadratoptimering under bivillkoret att optionspriser följer Dupires partiella differentialekvation. Vi utvecklar två algoritmer för att utföra optimeringen: en baserad på tekniker från optimal kontrollteori och en annan där en numerisk kvasi-Newton metod direkt appliceras på målfunktionen. Regularisering av problemet kan enkelt införlivas i båda problemformuleringarna. Metoderna testas på tre månaders data med marknadspriser på optioner på två stora aktieindex. De resulterade lokala volatilitetsytorna från båda metoderna ger priser som överensstämmer mycket väl med observerade marknadspriser. Hedging inom finans innebär att uppväga risken i ett finansiellt instrument genom att ta positioner i en eller flera andra handlade tillgångar. Kvadratisk hedging är en väl utvecklad teori för hedging av betingade kontrakt i inkompletta marknader genom att minimera replikeringsfelet i en passande L2-norm. Denna teori används emellertid inte i någon högre utsträckning av marknadsaktörer och relativt få vetenskapliga artiklar utvärderar hur väl kvadratisk hedging fungerar på verklig marknadsdata. Vi utvecklar ett ramverk för att jämföra hedgingstrategier och använder det för att empiriskt pröva hur väl kvadratisk hedging fungerar för europeiska köpoptioner på aktieindexet Euro Stoxx 50 när det modelleras med en affin stokastisk volatilitetsmodell med och utan hopp. Som jämförelse använder vi hedging i Black-Scholes modell.Vi visar att kvadratiska hedgingstrategier är signifikant bättre än hedging i Black-Scholes modell för optioner utanför pengarna och optioner nära pengarna med kort löptid när endast spot används i hedgen. När en annan option används i hedgen utöver spot är kvadratiska hedgingstrategier bättre än hedging i Black-Scholes modell även för optioner nära pengarna medmedellång löptid.

QC 20141121

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Griffiths, Michael Lee. "Multivariate calibration for ICP-AES." Thesis, University of Plymouth, 2001. http://hdl.handle.net/10026.1/1942.

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The analysis of metals is now a major application area for ICP-AES, however, the technique suffers from both spectral and non-spectral interferences. This thesis details the application of univariate and multivariate calibration methods for the prediction of Pt, Pd, and Rh in acid-digested and of Au, Ag and Pd in fusion-digested autocatalyst samples. Of all the univariate calibration methods investigated matrix matching proved the most accurate method with relative root mean square errors (RRMSEs) for Pt, Pd and Rh of 2.4, 3.7, and 2.4 % for a series of synihelic lest solutions, and 12.0, 2.4, and 8.0 % for autocatalyst samples. In comparison, the multivariate calibration method (PLSl) yielded average relative errors for Pt, Pd, and RJi of 5.8, 3.0, and 3.5 % in the test solutions, and 32.0, 7.5, and 75.0 % in the autocatalyst samples. A variable selection procedure has been developed enabling multivariate models to be built using large parts of the atomic emission spectrum. The first stage identified and removed wavelengths whose PLS regression coefficients were equal to zero. The second stage ranked the remaining wavelengths according to their PLS regression coefficient and estimated standard error ratio. The algorithms were applied to the emission spectra for the determination of Pt, Pd and Rh in a synthetic matrix. For independent test samples variable selection gave RRMSEs of 5.3, 2.5 and 1.7 % for Pt, Pd and Rh respectively compared with 8.3, 7.0 and 3.1 % when using integrated atomic emission lines. Variable selection was then applied for the prediction of Au, Ag and Pd in independent test fusion digests. This resulted in RRMSEs of 74.2, 8.8 and 12.2 % for Au, Ag and Pd respectively which were comparable to those obtained using a more traditional univariate calibration approach. A preliminary study has shown that calibration drift can be corrected using Piecewise Direct Standardisation (PDS). The application of PDS to synthetic test samples analysed 10 days apart resulted in RRMSEs of 4.14, 3.03 and 1.88%, compared to 73.04, 44.39 and 28.06 % without correction, for Pt, Pd, and Rh respectively.

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Nichol, Ryan James. "Calibration of the MINOS detectors." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406257.

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Dubus, Igor G. "Calibration of pesticide leaching models." Thesis, Cranfield University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269528.

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Brown, Susannah (Susannah R. ). "Thermal emission measurement and calibration." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51600.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.
Includes bibliographical references (leaf 51).
This thesis details a measurement setup and experimental procedures for emittance measurements using a Fourier transform infrared spectrometer. We calibrate the FTIR measurement system using measurements of a blackbody source at two temperatures to obtain the true emittance and absolute spectral radiance of our samples.
by Susannah Brown.
S.B.

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Haussamer, Nicolai Haussamer. "Model Calibration with Machine Learning." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29451.

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This dissertation focuses on the application of neural networks to financial model calibration. It provides an introduction to the mathematics of basic neural networks and training algorithms. Two simplified experiments based on the Black-Scholes and constant elasticity of variance models are used to demonstrate the potential usefulness of neural networks in calibration. In addition, the main experiment features the calibration of the Heston model using model-generated data. In the experiment, we show that the calibrated model parameters reprice a set of options to a mean relative implied volatility error of less than one per cent. The limitations and shortcomings of neural networks in model calibration are also investigated and discussed.

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Fernandez, Javier Oscar. "The Virginia Tech Calibration System." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/32669.

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Phasor measurement unit (PMU) applications on power grid monitoring systems have been implemented since the early ninetyâ s. Large monitoring system network performance relies on the consistent measurements of PMUs across the system. This has become a major challenge for designers since large networks use PMUs from various manufacturers who likely implement different synchrophasor technologies to perform the phasor estimations. The current synchrophasor standard, the IEEE C37.118-2005 Synchrophasor Standard, covers adequately the steady-state characterization of PMUs but does not specify transient condition requirements. The North American Synchrophasor Initiative (NASPI) has developed a guide outlining the several tests required for dynamic characterization of PMUs. The National Institute of Standards and Technology (NIST) developed two PMU testing stands for steady-state conformance with the current standard and for dynamic performance testing. Since May 2010, Virginia Tech has been working closely with the NIST in developing a PMU testing system similar to the NIST designs for commercial testing of PMUs and research purposes, the Virginia Tech Calibration System. This thesis focuses on assessing the system accuracy differences between the designs, and the software interface modifications to adapt the new hardware.
Master of Science

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Liu, Yang. "Calibration of Glass Fiber Microcantilevers." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1268336942.

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Kumar, Arun. "Sequential Calibration Of Computer Models." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1218568898.

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Dissertations / Theses on the topic 'Calibration'

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