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The Global ETD Search service is a free service for researchers
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 171 to 176 of 176 (0.03 seconds)| 171 |
Probing Electroweak Gauge Boson Scattering with the ATLAS Detector at the Large Hadron ColliderAnger, Philipp 07 October 2014 (has links) (PDF)
Electroweak gauge bosons as central components of the Standard Model of particle physics are well understood theoretically and have been studied with high precision at past and present collider experiments. The electroweak theory predicts the existence of a scattering process of these particles consisting of contributions from triple and quartic bosonic couplings as well as Higgs boson mediated interactions. These contributions are not separable in a gauge invariant way and are only unitarized in the case of a Higgs boson as it is described by the Standard Model. The process is tied to the electroweak symmetry breaking which introduces the longitudinal modes for the massive electroweak gauge bosons. A study of this interaction is also a direct verification of the local gauge symmetry as one of the fundamental axioms of the Standard Model. With the start of the Large Hadron Collider and after collecting proton-proton collision data with an integrated luminosity of 20.3/fb at a center-of-mass energy of 8 TeV with the ATLAS detector, first-ever evidence for this process could be achieved in the context of this work.
A study of leptonically decaying WWjj, same-electric-charge diboson production in association with two jets resulted in an observation of the electroweak WWjj production with same electric charge of the W bosons, inseparably comprising WW->WW electroweak gauge boson scattering contributions, with a significance of 3.6 standard deviations. The measured production cross section is in agreement with the Standard Model prediction.
In the course of a study for leptonically decaying WZ productions, methods for background estimation, the extraction of systematic uncertainties and cross section measurements were developed. They were extended and applied to the WZjj final state whereof the purely electroweakly mediated contribution is intrinsically tied to the scattering of all Standard Model electroweak gauge bosons: Wγ->WZ and WZ->WZ. Three charged leptons and a neutrino from the decay of the final state bosons allow inferences about the scattering process. A distinct signature is provided by the two accompanying tagging jets as remnants of the incoming quarks radiating the initial electroweak gauge bosons. The cross section of the electroweak WZjj production was measured to σ(fiducial, observed) = (0.63 +0.32 -0.28 (stat.) +0.41 -0.24 (syst.)) fb and was found to be consistent with the Standard Model prediction at next-to-leading order in perturbative quantum chromodynamics, σ(fiducial, theory) = (0.31 +0.03 -0.05) fb. Unfolded differential cross sections of kinematic variables sensitive to models of new physics were derived. Anomalous quartic electroweak gauge couplings are introduced as dimensionless coupling parameters of additional operators within an effective field theory approach. Constraints on the parameters of operators with dimension eight were set employing a unitarization prescription based on form factors.
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| 172 |
The relationship between the forward– and the realized spot exchange rate in South Africa / Petrus Marthinus Stephanus van HeerdenVan Heerden, Petrus Marthinus Stephanus January 2010 (has links)
The inability to effectively hedge against unfavourable exchange rate movements, using the
current forward exchange rate as the only guideline, is a key inhibiting factor of international
trade. Market participants use the current forward exchange rate quoted in the market to make
decisions regarding future exchange rate changes. However, the current forward exchange rate
is not solely determined by the interaction of demand and supply, but is also a mechanistic
estimation, which is based on the current spot exchange rate and the carry cost of the
transaction. Results of various studies, including this study, demonstrated that the current
forward exchange rate differs substantially from the realized future spot exchange rate. This
phenomenon is known as the exchange rate puzzle.
This study contributes to the dynamics of modelling exchange rate theories by developing an
exchange rate model that has the ability to explain the realized future spot exchange rate and
the exchange rate puzzle. The exchange rate model is based only on current (time t) economic
fundamentals and includes an alternative approach of incorporating the impact of the interaction
of two international financial markets into the model. This study derived a unique exchange rate
model, which proves that the exchange rate puzzle is a pseudo problem. The pseudo problem
is based on the generally excepted fallacy that current non–stationary, level time series data
cannot be used to model exchange rate theories, because of the incorrect assumption that all
the available econometric methods yield statistically insignificant results due to spurious
regressions. Empirical evidence conclusively shows that using non–stationary, level time series
data of current economic fundamentals can statistically significantly explain the realized future
spot exchange rate and, therefore, that the exchange rate puzzle can be solved.
This model will give market participants in the foreign exchange market a better indication of
expected future exchange rates, which will considerably reduce the dependence on the
mechanistically derived forward points. The newly derived exchange rate model will also have an influence on the demand and supply of forward exchange, resulting in forward points that are
a more accurate prediction of the realized future exchange rate. / Thesis (Ph.D. (Risk management))--North-West University, Potchefstroom Campus, 2011.
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| 173 |
The relationship between the forward– and the realized spot exchange rate in South Africa / Petrus Marthinus Stephanus van HeerdenVan Heerden, Petrus Marthinus Stephanus January 2010 (has links)
The inability to effectively hedge against unfavourable exchange rate movements, using the
current forward exchange rate as the only guideline, is a key inhibiting factor of international
trade. Market participants use the current forward exchange rate quoted in the market to make
decisions regarding future exchange rate changes. However, the current forward exchange rate
is not solely determined by the interaction of demand and supply, but is also a mechanistic
estimation, which is based on the current spot exchange rate and the carry cost of the
transaction. Results of various studies, including this study, demonstrated that the current
forward exchange rate differs substantially from the realized future spot exchange rate. This
phenomenon is known as the exchange rate puzzle.
This study contributes to the dynamics of modelling exchange rate theories by developing an
exchange rate model that has the ability to explain the realized future spot exchange rate and
the exchange rate puzzle. The exchange rate model is based only on current (time t) economic
fundamentals and includes an alternative approach of incorporating the impact of the interaction
of two international financial markets into the model. This study derived a unique exchange rate
model, which proves that the exchange rate puzzle is a pseudo problem. The pseudo problem
is based on the generally excepted fallacy that current non–stationary, level time series data
cannot be used to model exchange rate theories, because of the incorrect assumption that all
the available econometric methods yield statistically insignificant results due to spurious
regressions. Empirical evidence conclusively shows that using non–stationary, level time series
data of current economic fundamentals can statistically significantly explain the realized future
spot exchange rate and, therefore, that the exchange rate puzzle can be solved.
This model will give market participants in the foreign exchange market a better indication of
expected future exchange rates, which will considerably reduce the dependence on the
mechanistically derived forward points. The newly derived exchange rate model will also have an influence on the demand and supply of forward exchange, resulting in forward points that are
a more accurate prediction of the realized future exchange rate. / Thesis (Ph.D. (Risk management))--North-West University, Potchefstroom Campus, 2011.
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| 174 |
Probing Electroweak Gauge Boson Scattering with the ATLAS Detector at the Large Hadron ColliderAnger, Philipp 01 September 2014 (has links)
Electroweak gauge bosons as central components of the Standard Model of particle physics are well understood theoretically and have been studied with high precision at past and present collider experiments. The electroweak theory predicts the existence of a scattering process of these particles consisting of contributions from triple and quartic bosonic couplings as well as Higgs boson mediated interactions. These contributions are not separable in a gauge invariant way and are only unitarized in the case of a Higgs boson as it is described by the Standard Model. The process is tied to the electroweak symmetry breaking which introduces the longitudinal modes for the massive electroweak gauge bosons. A study of this interaction is also a direct verification of the local gauge symmetry as one of the fundamental axioms of the Standard Model. With the start of the Large Hadron Collider and after collecting proton-proton collision data with an integrated luminosity of 20.3/fb at a center-of-mass energy of 8 TeV with the ATLAS detector, first-ever evidence for this process could be achieved in the context of this work.
A study of leptonically decaying WWjj, same-electric-charge diboson production in association with two jets resulted in an observation of the electroweak WWjj production with same electric charge of the W bosons, inseparably comprising WW->WW electroweak gauge boson scattering contributions, with a significance of 3.6 standard deviations. The measured production cross section is in agreement with the Standard Model prediction.
In the course of a study for leptonically decaying WZ productions, methods for background estimation, the extraction of systematic uncertainties and cross section measurements were developed. They were extended and applied to the WZjj final state whereof the purely electroweakly mediated contribution is intrinsically tied to the scattering of all Standard Model electroweak gauge bosons: Wγ->WZ and WZ->WZ. Three charged leptons and a neutrino from the decay of the final state bosons allow inferences about the scattering process. A distinct signature is provided by the two accompanying tagging jets as remnants of the incoming quarks radiating the initial electroweak gauge bosons. The cross section of the electroweak WZjj production was measured to σ(fiducial, observed) = (0.63 +0.32 -0.28 (stat.) +0.41 -0.24 (syst.)) fb and was found to be consistent with the Standard Model prediction at next-to-leading order in perturbative quantum chromodynamics, σ(fiducial, theory) = (0.31 +0.03 -0.05) fb. Unfolded differential cross sections of kinematic variables sensitive to models of new physics were derived. Anomalous quartic electroweak gauge couplings are introduced as dimensionless coupling parameters of additional operators within an effective field theory approach. Constraints on the parameters of operators with dimension eight were set employing a unitarization prescription based on form factors.
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Koexistence mobilních komunikačních systémů GSM-EDGE a UMTS / GSM-EDGE and UMTS Systems CoexistenceGleissner, Filip January 2009 (has links)
The dissertation thesis deals with the investigation of the coexistence of GSM–EDGE and UMTS systems with focus on the physical layer of the systems. The aim is to provide a set of recommendations for practical cooperation while the systems operate in both the separated and the common radio bands. A detailed description of signal processing of both the systems on the physical layer is presented. On the basis of this description, models of both systems were created and implemented in the MATLAB environment. The simulations are focused on the physical layer quality parameters, especially the bit error ratio evaluation for various ratios of useful signal power to noise power during the transmission over the radio channel. Simulation is also used to examine the quality of received useful signal while it is interfered by signals from the same and adjacent channels. The purpose is to determine the isolation between these adjacent channels, when the bit error ratio of the useful signal does not exceed a certain reference value. The simulation results are subsequently subjected to comparison with the results of the experimental measurements in laboratory conditions. Before the measurements are carried out, a study of possible interference types is performed. Consequently, the crucial parameters of the measuring equipment used are verified. From the results of simulations and measurements, the proposal of a minimum and recommended carrier separation between both the systems is presented in order to efficiently utilize the assigned frequency spectrum. Furthermore, for the cooperation in both the separated and the common radio bands, the necessary precautions are given for reaching the required isolation and thereby inter-system interference minimization.
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Návrh hardwarového šifrovacího modulu / Design of hardware cipher moduleBayer, Tomáš January 2009 (has links)
This diploma’s thesis discourses the cryptographic systems and ciphers, whose function, usage and practical implementation are analysed. In the first chapter basic cryptographic terms, symmetric and asymetric cryptographic algorithms and are mentioned. Also usage and reliability are analysed. Following chapters mention substitution, transposition, block and stream ciphers, which are elementary for most cryptographic algorithms. There are also mentioned the modes, which the ciphers work in. In the fourth chapter are described the principles of some chosen cryptographic algorithms. The objective is to make clear the essence of the algorithms’ behavior. When describing some more difficult algorithms the block scheme is added. At the end of each algorithm’s description the example of practical usage is written. The chapter no. five discusses the hardware implementation. Hardware and software implementation is compared from the practical point of view. Several design instruments are described and different hardware design programming languages with their progress, advantages and disadvantages are mentioned. Chapter six discourses the hardware implementation design of chosen ciphers. Concretely the design of stream cipher with pseudo-random sequence generator is designed in VHDL and also in Matlab. As the second design was chosen the block cipher GOST, which was designed in VHDL too. Both designs were tested and verified and then the results were summarized.
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