Dissertations / Theses on the topic 'Cross section'

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1

Lamo, Ana Rosa. "Cross section distribution dynamics." Thesis, London School of Economics and Political Science (University of London), 1996. http://etheses.lse.ac.uk/1448/.

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This thesis contains four chapters. Each chapter constitutes an empirical exercise in which I apply econometric ideas on studying the dynamics of large cross sections of data (Random Fields). Three of them concern the empirics of convergence and the fourth analyses business cycle fluctuations. The first, "Notes on Convergence Empirics: Some Calculations for Spanish Regions," describes the econometric methods for studying the dynamics of the distributions and how to characterise convergence in this framework, explains why the standard cross-section regression analysis is misleading when testing for convergence and then performs some calculations for regions in Spain. The second chapter, "Dynamics of the Income Distribution Across OECD Countries", considers its baseline hypotheses to be those generated by the Solow growth model. Using sequential conditioning, it studies whether the convergence hypothesis implications can be shown to hold for the OECD economies. It finds that neither absolute nor conditional convergence, in the sense of economies approaching the OECD average, has taken place. The third chapter, "Cross Sectional Firm Dynamics: Theory and Empirical Results", extends ideas of distribution dynamics to a discrete choice setting, and extends the reasoning of Galton's Fallacy to the logit model. It provides evidence of the tendency of firm sizes to converge for the US chemicals sector by analysing dynamically evolving cross-section distributions. Finally, the fourth chapter, "Unemployment in Europe and Regional Labour Fluctuations" applies distribution dynamics ideas to a business cycle setting. It analyses the dynamics of employment for 51 European regions from 1960 to 1990, addressing the issue of whether regional shocks have aggregate effects on unemployment or the opposite. It uses a model for non-stationary evolving distributions to identify idiosyncratic and aggregate disturbances.
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Tosetti, Elisa. "Cross section dependence in panels." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611351.

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3

Li, Xiang. "Compressive Radar Cross Section Computation." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40073.

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Compressive Sensing (CS) is a novel signal-processing paradigm that allows sampling of sparse or compressible signals at lower than Nyquist rate. The past decade has seen substantial research on imaging applications using compressive sensing. In this thesis, CS is combined with the commercial electromagnetic (EM) simulation software newFASANT to improve its efficiency in solving EM scattering problems such as Radar Cross Section (RCS) of complex targets at GHz frequencies. This thesis proposes a CS-RCS approach that allows efficient and accurate recovery of under-sampled RCSs measured from a random set of incident angles using an accelerated iterative soft thresh-holding reconstruction algorithm. The RCS results of a generic missile and a Canadian KingAir aircraft model simulated using Physical Optics (PO) as the EM solver at various frequencies and angular resolutions demonstrate good efficiency and accuracy of the proposed method.
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NOVO, MARCELA SILVA. "ARBITRARY CROSS SECTION WAVEGUIDES: ANALYSIS OF MODAL FIELDS AND OF DISCONTINUITIES BETWEEN ARBITRARY CROSS SECTION WAVEGUIDES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3781@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
No presente trabalho o método de Rayleigh-Ritz é utilizado na determinação dos campos modais e dos números de onda de corte em guias de onda de seção arbitrária. Inicialmente, o método é aplicado com funções de base polinomiais, sendo a seção transversal do guia aproximada por um polígono convexo. Este tipo de função limitou o número de modos que podem ser calculados, uma vez que polinômios de grau alto geram instabilidades computacionais e overflow. Utilizando a mesma metodologia, os campos modais em guias de onda superquadráticos são analisados. Entretanto, as funções de base polinomiais são substituídas por funções trigonométricas, produzindo um modelo numérico capaz de computar um grande número de modos em um tempo de execução razoável. Os guias superquadráticos constituem uma classe de guias uniformes, incluindo guias circulares, elípticos, quase retangulares e outros de seções intermediárias. Conseqüentemente, eles são úteis na construção de diversos dispositivos em guias de onda, incluindo transições de diferentes seções, tais como circular para elíptica e circular para retangular. O método do casamento de modos é aplicado na determinação da matriz de espalhamento de descontinuidades entre guias superquadráticos. Diversas aplicações numéricas são apresentadas e comparadas com resultados obtidos através de outras técnicas.
In the present work, the modal fields and cutoff wavenumbers of arbitrary cross section waveguides are determined using the Rayleigh-Ritz method. Initially, the method is applied to waveguides with cross section approximated by a convex polygon. Polynomial basis functions are used. Such basis functions limit the number of modes that can be computed, since polynomials of high degree generate computer instabilities and overflow. Using the same methodology, the modal fields of superquadric waveguides are analyzed. Polynomial basis functions are replaced by trigonometric functions, however, producing an efficient numerical model capable of computing a large number of modes with a reasonable computer time. Superquadric waveguides constitute a class of uniform waveguides that include circular, elliptical, almost rectangular waveguides and a series of intermediate cross section waveguides. As a consequence they are quite useful in the construction of several devices, including transitions between waveguides of different cross sections, such as circular to elliptical and circular to rectangular. The mode matching technique is applied to the determination of the scattering matrix of discontinuities between superquadric waveguides. Several numerical applications are presented and compared to results obtained from other techniques.
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Britton, Michael C. "Practical square cross-section helical antennas." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/MQ43337.pdf.

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6

Abhakorn, Pongrapeeporn. "The cross-section of stock returns." Thesis, University of York, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428059.

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7

Britton, Michael C. (Michael Charles) Carleton University Dissertation Engineering Electronics. "Practical square cross-section helical antennas." Ottawa, 1999.

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8

Salvador, Castiñeira Paula. "Neutron-induced fission cross section of 240,242Pu." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/284746.

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A recent sensitivity analysis done for the new generation of fast reactors [1] has shown the importance of improved cross section data for several actinides. Among them, the neutron-induced fission cross section of 240,242Pu requires a level of accuracy of 1-3% and 3-5%, respectively, from the current status of 6% and 20%. Moreover, nearly all the measurements in the literature have been done relative to 235U(n,f). Therefore, using other references samples such as 237Np or 238U will provide the scientific community with more valuable data. The work was carried out at the Institute for Reference Materials and Measurements (JRC-IRMM). The Van de Graaff accelerator was used for producing a quasi-monoenergetic neutron flux in the energy range of 0.3MeV to 3MeV. Protons were accelerated thanks to a potential difference. A neutron producing target was placed at the end of the beam line: 7Li(p,n)7Be or T(p,n)3He. Then, a twin Frisch-grid ionization chamber (TFGIC) was used as detector. The setup of the detector consists in a common cathode, two anodes and two grids. In the cathode the sample under study and the reference sample are placed in a back-to-back configuration. Each electrode is connected to a preamplifier, and then to a 100MHz 12 bit waveform digitizer. All raw signals are stored for an offline analysis using C++ under the ROOT framework. All the samples used were produced by the target preparation group at JRC-IRMM. The enrichment of the plutonium samples was of 99.89% for 240Pu and of 99.97% for 242Pu. The plutonium masses were chosen to minimize their alpha activity (0.8MBq for 240Pu and 0.1MBq for 242Pu). Three different reference fission cross sections were employed: 235U(n,f), 238U(n,f) and 237Np(n,f). The mass of all the reference samples used was remeasured by means of low geometry alpha counting or/and by a single grid ionization chamber. The mass uncertainty of each sample was lower than 2%. Results were obtained not only for the neutron-induced fission cross section of 240,242Pu in the region from 0.3 MeV up to 3 MeV, but for the 238U(n,f) cross section and the 237Np(n,f) cross section. The neutron flux from the Van de Graaff was characterized by means of MCNP simulations. A clear influence of the different structures between the neutron producing targets and the deposits was found, specially when the ratios measured involved a fissile sample and a threshold sample. The spontaneous fission of 240,242Pu is, as well, an important correction. Thus, this property was measured independently in this work, reaching an uncertainty lower than 1.3% for both isotopes. More corrections were due to the high electronic threshold needed to not trigger on alpha particles, the fission fragment loss due to the sample thickness, neutron emission anisotropy, etc. On average the results of the 240,242Pu(n,f) cross section are in agreement with previous experimental data, even though the trend is slightly lower than present evaluations. In the case of 242Pu(n,f) cross section the resonance-peak structure at 1.1 MeV could not be reproduced in any case. The results of the 237Np(n,f) cross section show an increase at the plateau region with respect to the ENDF/B-VII.1 evaluation in the same way as the data from Paradela (2010) [2]. The results for the 238U(n,f) cross section show a higher cross section than the ENDF evaluation but in agreement with the present JEFF 3.2 evaluation. [1] Uncertainty and target accuracy assessment for innovative systems using recent covariance data evaluations, Volume 26, 2008, OECD-NEA [2] Paradela, C. et al., Neutron-induced fission cross section of U-234 and Np-237 measured at the CERN Neutron Time-of-Flight (n_TOF) facility.,Physical Review C. 82, 3, 034601 (2010)
Un anàlisi de sensitivitat [1] recent per la nova generació de reactors ràpids va mostrar la importància de millorar les seccions eficaç de varis actínids. Entre ells, la secció eficaç de fissió per neutró induït del 240,242Pu requereix una millora en la seva precisió des d'un 6% a un 1-3% pel 240Pu i des d'un 20% a un 3-5% pel 242Pu. A més, quasi bé totes les dades experimentals disponibles a la literatura han estat determinades relatives a la secció eficaç del 235U(n,f). Per tant, la utilització d'altres isòtops com a referències, tal com el 237Np(n,f) o el 238U(n,f), proveirà a la comunitat científica amb dades valuoses. Aquest treball ha estat realitzat a l'Institute for Reference Materials and Measurements (JRC-IRMM). L'accelerador Van de Graaff disponible al JRC-IRMM s'ha emprat per produir un flux de neutrons quasi mono-energètics en el rang de 0.3 MeV a 3 MeV. Els protons van ser accelerats de fer-los impactar amb una mostra de producció de neutrons: 7Li(p,n)7Be o T(p,n)3He. A continuació, una doble cambra d'ionització amb grid (TFGIC) es va emplaçar com a detector consistent en un càtode, dos ànodes i dos grids. En el càtode es situen la mostra a estudiar i la mostra de referència. Cada un dels elèctrodes és connectat a un preamplificador i, a continuació, a un digitilitzador amb una freqüència de 100 MHz i 12 bit. Les senyals originals són emmagatzemades sense cap tractament previ per a un posterior anàlisi. El tractament de dades es va realitzar mitjançant el codi de programació C++ sota el marc de ROOT. Totes les mostres emprades en aquest experiment s'han produït al grup de preparació de mostres del JRC-IRMM. L'enriquiment de les mostres de plutoni era de 99.89% pel 240Pu (0.8MBq) i del 99.97% pel 242Pu (0.1MBq). La massa de les tres mostres de referència (235U(n,f), 238U(n,f) i 237Np(n,f)) també va ser mesurada. La incertesa de cada massa és inferior al 2%. La principal correcció aplicaca als resultats obtinguts ha estat per la caracterització del flux de neutrons mitjançant el codi de simulació Monte Carlo MCNP. Els resultats de les simulacions han mostrat una clara influència de les diferents estructures emplaçades entre la mostra de producció de neutrons i les mostres de fissió. Altres correccions s¿han realitzat per la fissió espontània del 240,242Pu (mesurada independentment en aquest treball amb una incertesa inferior al 1,3%), la deficiència d'esdeveniments a causa del llindar de detecció, l'eficiència del detector, l'anisotropia en l'emissió dels neutrons, etc. Tot i que el principal objectiu va ser l'obtenció de la secció eficaç de fissió per neutró induït del 240,242Pu en la regió de 0.3 MeV a 3 MeV, resultats addicionals han estat obtinguts per la secció eficaç del 238U(n,f) i el 237Np(n,f). Els resultats obtinguts mostren un acord significatiu entre la secció eficaç del 240,242Pu(n,f) i resultats experimentals anteriors, tot i que la tendència és lleugerament inferior a les avaluacions (ENDF/B-VII.1, JEFF 3.1 i JENDL 4.0) disponibles. En el cas de la secció eficaç del 242Pu(n,f), a més, el pic de ressonància al voltant de 1.1 MeV predit per quasi totes les dades experimentals anteriors i les avaluacions actuals no s'ha reproduït en aquest experiment. Els resultats de la secció eficaç del 237Np(n,f) presenten un increment en la regió plana després del llindar de fissió d'un 5-7% respecte l'avaluació ENDF/B-VII.1, i en concordança amb els resultats obtinguts per Paradela (2010) [2]. Finalment, els resultats de la secció eficaç del 238U(n,f) mostren un increment al voltant d'un 7-9% a la zona plana després del llindar de fissió, aquesta predicció concorda amb l'avaluació JEFF 3.2. [1] Uncertainty and target accuracy assessment for innovative systems using recent covariance data evaluations, Volume 26, 2008, OECD-NEA [2] Paradela, C. et al., Neutron-induced fission cross section of U-234 and Np-237 measured at the CERN Neutron Time-of-Flight (n_TOF) facility.,Physical Review C. 82, 3, 034601 (2010)
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9

Tesinsky, Milan. "MCNPX Simulations for Neutron Cross Section Measurements." Licentiate thesis, KTH, Reactor Physics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12929.

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This thesis presents MCNPX simulations of the SCANDAL set-up used at the Theodor Svedberg Laboratory for neutron scattering cross-section measurements. The thesis describes processes and data important for the upcoming off-line data analysis. In the experiment, neutrons scattered off the target are converted to protons which are stopped in scintillator crystals. The results of presented simulations include a description of the proton spectra in dependence of the neutron-to-proton conversion angle, calculation of the hit position gates and a study of the converter describing the role of its chemical composition and also the role of other plastic scintillator on the proton spectra.


QC 20100520
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10

Grijpink, Sjors Johannes Louis Assuerus. "Charged current cross section measurement at HERA." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/72835.

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11

Haddad, A. "Supersonic nozzle design of arbitrary cross-section." Thesis, Cranfield University, 1988. http://hdl.handle.net/1826/3512.

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An investigation, both theoretical and experimental in nature, has been undertaken to develop a simple method for the design of supersonic nozzles and, indeed, inlets of quite complex shapes from known or calculated axisymmetric flowfields. 1he axisymmetric flowfield is determined using a computer program based on the method of characteristics. Streamlines are calculated by direct integration of the axisymmetric stream function. 7he desired shape is chosen at the exit of the computed axisymmetric nozzle having the desired length and Mach number. Its describing points are then traced along the corresponding streamlines back to the throat. Streamsheets formed by these streamlines define the new shape. Following this approach, two three-dimensional nozzles were designed : one of elliptical cross-section and a two-dimensional wedge. Flows within the two configurations were further simulated using a general purpose three-dimensional CFD code, "PHOENICS", while the elliptical nozzle was subsequently manufactured and submitted to experimental tests. Results from the experimental tests and three-dimensional numerical simulation, as well as predictions of the performance of the nonaxisymmetric nozzles and their axisymmetric counterparts were obtained and compared. Good agreement was achieved between the several components of the study demonstrating that it is possible, using this relatively simple method, to design satisfactory three-dimensional nozzles.
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Dallmann, Thomas [Verfasser]. "Polarimetric Radar Cross-Section Imaging / Thomas Dallmann." München : Verlag Dr. Hut, 2017. http://d-nb.info/1149580321/34.

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Koh, Woo Hwa. "Essays on the Cross-section of Returns." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1436980305.

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Hughes, E. J. "Radar cross section modelling using genetic algorithms." Thesis, Department of Aerospace and Sensors, 2009. http://hdl.handle.net/1826/3263.

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In the design of new, more sophisticated missile systems, simulations need to be realistic and fast. Realistic target models are just as important as realistic models of the missile, but have often been overlooked in the past. Existing methods for creating realistic target models require considerable computational resources. This thesis addresses the problem of using limited resources to create realistic target models for simulating engagements with radar guided homing missiles. A multiple genetic algorithm approach is presented for converting inverse synthetic aperture radar images of targets into scatterer models. The models produced are high fidelity and fast to process. Results are given that demonstrate the generation of a model from real data using a desktop computer. Realistic models are used to investigate the effects of target fidelity on the missile performance. The results of the investigation allow the model complexity to be traded against the fidelity of the representation to optimise simulation speed. Finally, a realistic target model is used in a feasibility study to investigate the potential use of glint for target manoeuvre detection. Target glint is considered as noise in conventional missile systems and filtered to reduce its effects on the tracking performance- The use of glint for target manoeuvre detection would provide a cheap and novel alternative to the optical techniques currently being developed. The feasibility study has shown that target manoeuvre detection using glint may be as fast as optical techniques and very reliable.
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Gottlieb, James Harold 1954. "Torsional properties of an ovaline cross section." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/292023.

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Torsional properties of a solid, linearly elastic, and isotropic bar with the cross section in the shape of an ovaline were investigated. An ovaline is a variant of an ellipse defined by the parametric equations: x = a(1 + αcos²λ)cosλ, and y = b(1 + βsin²λ)sinλ. Only ovalines with a smooth, aerodynamic type of cross section under St. Venant torsion were considered. The torsional properties of interest included the maximum shear stress component, the maximum shear stress magnitude and the torsional stiffness. The results from twenty-eight finite element models were correlated to several candidate solutions for each of the torsional properties based on variances of the classical elliptical solution. Correction factors are provided where appropriate. The recommended methods of solution provide highly accurate results for the class of ovalines considered in a fraction of the time required to obtain results via the finite element method.
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Schincaglia, Michele <1987&gt. "Differentiation in the Cross-Section of Returns." Master's Degree Thesis, Università Ca' Foscari Venezia, 2022. http://hdl.handle.net/10579/20613.

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CAPM (Sharpe, Lintner) is a model of market equilibrium where pricing is determined by the asset correlation with systemic market risk. An informationally efficient market should set CAPM excess risk premium at zero. APT model (Ross) indicates the existence of an excess premium whenever other risk factors are not priced by CAPM. The aim of this work is to investigate whether the degree of product differentiation is a significant proxy for risk to be included within the pricing kernel.
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Waddell, Rachel C. "Radar cross section synthesis of doubly curved surfaces." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA305445.

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Faros, Nikolaos I. "Radar cross section synthesis for planar resistive surfaces." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA290151.

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19

Feng, Sitao. "Image Analysis on Wood Fiber Cross-Section Images." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-156428.

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Lignification of wood fibers has a significant impact on wood properties. To measure the distribution of lignin in compression wood fiber cross-section images, a crisp segmentation method had been developed. It segments the lumen, the normally lignified cell wall and the highly lignified cell wall of each fiber. In order to refine this given segmentation the following two fuzzy segmentation methods were evaluated in this thesis: Iterative Relative Multi Objects Fuzzy Connectedness and Weighted Distance Transform on Curved Space. The crisp segmentation is used for the multi-seed selection. The crisp and the two fuzzy segmentations are then evaluated by comparing with the manual segmentation. It shows that Iterative Relative Multi Objects Fuzzy Connectedness has the best performance on segmenting the lumen, whereas Weighted Distance Transform on Curved Space outperforms the two other methods regarding the normally lignified cell wall and the highly lignified cell wall.
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Vigilar, Gregorio G. "Numerical simulation of an optimal channel cross-section." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-11012008-063227/.

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Demiris, John. "Radar cross section of a planar fractal tree." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27232.

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Electromagnetic scattering from trees and vegetation is of prime importance in radar and remote sensing. The actual problem of scattering from trees is rather complicated and involves three dimensional scattering from lossy, electrically large, and randomly oriented objects. In this thesis, the radar cross section of a planar fractal tree is considered. Although a planar tree is far from being real, scattering from it shed light on the scattering phenomenon from an actual tree. The planar tree is generated using fractal geometry and its branches are considered perfectly conducting. The tree is illuminated by a plane wave and the problem is solved using the moment method. Data is presented for the radar cross section for different branching angles of the tree and at different frequencies
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Ton, Cuong. "Radar cross section (RCS) simulation for wind turbines." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34754.

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Approved for public release; distribution is unlimited
Wind-turbine power provides energy-independence and greenhouse-gas reduction benefits, but if wind turbines are built near military and commercial radar and communication installations, they can cause degradation in the systems performance. The purpose of this research is to study the radar cross section (RCS) of a wind turbine and assess its effect on the performance of radar and communication systems. In this research, some basic scattering characteristics of wind turbines are discussed. Several computational methods of RCS prediction are examined, citing their advantages and disadvantages. Modeling and computational issues that affect the accuracy and convergence of the simulation results are discussed. RCS simulation results for two wind turbine configurations are presented: a horizontal axis, three-blade design and a vertical axis helical design. Several methods of mitigating wind turbine clutter are discussed. Issues of RCS reduction and control for wind turbines are also addressed.
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FRANCESCHIN, BERNARDO BIANCHI. "VISUALIZATION OF ARBITRARY CROSS SECTION OF UNSTRUCTURED MESHES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=23874@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
PROGRAMA DE EXCELENCIA ACADEMICA
Na visualização de campos escalares de dados volumétricos, o uso de seções de corte é uma técnica eficaz para se inspecionar a variação do campo no interior do domínio. A técnica de visualização consiste em mapear sobre a superfície da seção de corte um mapa de cores, o qual representa a variação do campo escalar na interseção da superfície com o volume. Este trabalho propõe um método eficiente para o mapeamento de campos escalares de malhas não estruturadas em seções de corte arbitrárias. Trata-se de um método de renderização direta (a interseção da superfície com o modelo não é extraída) que usa a GPU para garantir bom desempenho. A idéia básica do método proposto é utilizar o rasterizador da placa gráfica para gerar os fragmentos da superfície de corte e calcular a interseção de cada fragmento com o modelo em GPU. Para isso, é necessário testar a localização de cada fragmento na malha não estruturada de maneira eficiente. Como estrutura de aceleração, foram testadas três variações de grades regulares para armazenar os elementos (células) da malha, e cada elemento é representado pela lista de planos de suas faces, facilitando o teste de pertinência fragmento-elemento. Uma vez determinado o elemento que contém o fragmento, são aplicados procedimentos para interpolar o campo escalar e para identificar se o fragmento está próximo à fronteira do elemento, a fim de representar o aramado (wireframe) da malha na superfície de corte. Resultados obtidos demonstram a eficácia e a eficiência do método proposto.
For the visualization of scalar fields in volume data, the use of cross sections is an effective technique to inspect the field variation inside the domain. The technique consists in mapping, on the cross section surfaces, a colormap that represents the scalar field on the surfasse-volume intersection. In this work, we propose an efficient method for mapping scalar fields of unstructured meshes on arbitrary cross sections. It is a direct-rendering method (the intersection of the surface and the model is not extracted) that uses GPU to ensure efficiency. The basic idea is to use the graphics rasterizer to generate the fragments of the cross-section surface and to compute the intersection of each fragment with the model. For this, it is necessary to test the location of each fragment with respect to the unstructured mesh in an efficient way. As acceleration data structure, we tested three variations of regular grids to store the elements (cells) of the mesh, and each elemento is represented by the list of face planes, easing the in-out test between fragments and elements. Once the element that contains the fragment is determined, it is applied procedures to interpolate the scalar field and to check if the fragment is close to the element boundary, to reveal the mesh wireframe on the surface. Achieved results demonstrate the effectiveness and the efficiency of the proposed method.
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DiPerna, Daniel T. "Sound scattering by cylinders of noncircular cross section." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/35370.

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Sursock, Jean-Paul 1974. "The cross section of expected stock returns revisited." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9218.

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Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2000.
Also available online at the DSpace at MIT website.
Includes bibliographical references (leaves 60-61).
We review and extend two important empirical financial studies: Fama and MacBeth [1973] and Fama and French [1992]. Fama and MacBeth [1973] sort stocks on the New York Stock Exchange into 20 portfolios based on their market [beta]. They test for, and conclude that, [beta] does in fact explain the cross-sectional variation in average stock returns for the 1926-1968 period. After we replicate the results in their study we extend their work to the most current data. The coefficients and t-statistics for five-year sub-periods exhibit roughly the same properties during the last half of the century as they did during the period originally studied. Fama and MacBeth report statistically significant results for their overall period (1935-1968) as well. When we run the same test on the all the data currently available (1935-1998) we find that the t-statistics are lower, instead of higher, than they were for the 1935-1968 period. We run several variations on the Fama and MacBeth [1973] paper. For example, we vary the exchanges (NYSE, AMEX, and/or NASDAQ) and indexes (value-weighted or equally-weighted) employed. We also study the effect of using robust (least absolute deviation) regressions instead of ordinary least squares. In all cases, the results are similar to those described above. Fama and French [1993] show that, when size is controlled for, market [beta] does not explain the cross-sectional variation in returns for the 1963-1990 period. They find that two other variables, size (market equity) and book-to-market equity, combine to capture the cross-sectional variation in average stock returns during the same period. After replicating their results, we update the study to the most current data. We find that the t-statistics for size and book-to-market equity are more significant during the 1963-1998 period than they were for the 1963-1990 period. We also confirm that [beta] is statistically insignificant during the 1963-1998 period.
by Jean-Paul Sursock.
S.M.
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26

Redmond, Everett Lee. "Multigroup cross section generation via Monte Carlo methods." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10405.

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27

Tari, Ilker. "Homogenized cross section determination using Monte Carlo simulation." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28054.

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28

Whang, Min Cheol. "Stress analysis of the diseased arterial cross-section." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/8694.

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29

Sjögren, Johan. "Pion photoproduction cross section at large momentum transfer." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6239/.

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The Real Compton Scattering experiment was performed in all A at the Thomas Jefferson National Accelerator Facility. It was designed to measure, for Compton scattering and π 0 -photoproduction, the differential cross section over a range of kinematic points and the polarisation transfer to the proton at a single kinematic point. The full range of the experiment in Mandelstam variables t and s was 1.64−6.46 GeV 2 and 4.82−10.92 GeV 2 respectively with beam energies of 2−6 GeV. The motivation for the experiment is to test the cross section and polarisation trans- fer predictions of perturbative QCD versus that of predictions from Generalised Parton Distribution models. This thesis will give an overview of the pertinent theory, experimental setup in Hall A and the extracting of the π 0 -photoproduction cross section.
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30

Wilson, Peter J. "B* cross section and B*-B mass difference /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487779439847052.

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31

Willis, Barton L. "Multigroup transport equations with nondiagonal cross section matrices." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/49963.

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It is shown that multigroup transport equations with nondiagonal cross section matrices arise when the modal approximation is applied to energy dependent transport equations. This work is a study of such equations for the case that the cross section matrix is nondiagonalizable. For the special case of a two-group problem with a noninvertible scattering matrix, the problem is solved completely via the Wiener-Hopf method. For more general problems, generalized Chandrasekhar H equations are derived. A numerical method for their solution is proposed. Also, the exit distribution is written in terms of the H functions.
Ph. D.
incomplete_metadata
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32

Volk, Erik. "Measurement of the D*+/- cross-section at HERMES." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8986383.

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33

Camboni, Alessandro. "Inclusive b-jet production cross section measurement at LHCb." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/129459.

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The LHCb detector features an outstanding capability to identify displaced secondary vertices with respect to the interaction point. The extraordinary performance of the whole LHCb tracking system makes possible accurate measurements for particles’ trajectories and momenta. Many lifetime and kinematic based properties of the decay of the long-lived B hadrons are at the basis of the identification of b-jets, thus the LHCb detector could prove to be suitable to perform QCD studies based on heavy-quark jets. The aim of the analysis is to calculate the inclusive bb quark pair production cross section inside the range η ∈ (2.5, 4.0). For this purpose, a cone jet algorithm has been developed to reconstruct and identify jets from the B decay. It relies on how well the measured B hadron approximates the properties of the b quark in order to infer the cross section of b quarks production. Monte Carlo productions of fully simulated events in which a b quark pair has been produced have been used to study the correlation between the emerging quarks and the resulting B hadron pairs. Due to the large mass of the b quark, for which it turns to be less affected by non-perturbative QCD effects than lighter quarks, most of the properties of the b are retained by the corresponding B hadron. Thus may be safe to infere the b production cross section from inclusive B final states. The method used here is also expected to be less affected by non-perturbative effects than other measurements based on exclusive channel decays. The jet reconstruction tool developed to identify the jets originating from the b quark hadronisation is a cone-type seeded algorithm: the basic idea is to take an inclusive secondary vertex originating from the long-lived B hadron as seed for jet reconstruction. The position of the seed with respect to the primary verted establishes the direction of a cone of given aperture. The jet is then built collecting charged and neutral particles that are found to be inside the cone. The radius of the cone is expressed in terms of the dimensionless parameter Rin the (φ, η) plane (azimuthal angle and pseudorapidity). Seed track candidates are properly preselected with requirements on transverse momentum, χ2 of the resulting track fit and impact paramenter significance IPS (= IP/σIP) with respect to the PV. Goodness of vertex is ensured with cuts on the resulting vertex fit χ2 and on the distance of closest approach between the two tracks (DOCA). The reconstructed seed are found to describe well the B hadron direction: the φ and θ resolution evaluated for signal seeds turns out to be (15.8 ± 0.2) mrad and (1.82 ± 0.18) mrad respectively. Jets are then built and their properties studied, such as their b-tagging efficiency and spatial overlapping. Monte Carlo simulations have also been used to study the LHCb trigger. A handful of trigger lines have been selected meeting the following requirements: good efficiency in selecting signal events, the inclusive feature of the analysis must be preserved, difficult evaluation of systematic effects has to be avoided. A jet energy correction has been studied and applied in order to account for energy loss due to undetected particles or wrong energy measurement and tracking. This allows to compare Monte Carlo and real data and define a fiducial cut on the transverse momentum of the jets. Events are finally selected requiring them:  to have only one reconstructed primary vertex (to avoid ambiguous assignation of tracks to the proper primary vertex);  to have at least one reconstructed secondary vertex;  to be accepted by at least one line of each trigger stage. The measurement has been performed using 17.7 pb−1 of data, about ½ of the total luminosity collected in 2010 at 7Tev. Background from c-jets and light quarks and gluons has been studied using LHCb Monte Carlo simulations. The bbˉ production cross has been found to be σbbˉ = 80.6 ± 1.2 (stat) ± 11.4 (syst) μb, compatible within 1 sigma with NLO predictions.
El colisionador de hadrones superconductor LHC es el accelerador de partículas de energía más alta del mundo, actualmente produce colisiones de protones a un energía en el centro de masa de sqrt{s}=8 TeV. El detector LHCb es dedicado al estudio de física de los sabores pesados en LHC. Su objetivo principal es buscar evidencias indirectas de nueva física en la violación CP y en los decaimientos raros de los hadrones que contienen quarks b y c. La excelente capacidad de LHCb para identificar vértices desplazados de decaimientos de hadrones B se basa en un localizador de trazas de silicio (VELO) puesto alrededor del punto de interacción. Las prestaciones del VELO garantizan una resolución espacial altamente superiór a los demás experimentos situados en en LHC. Una identificación eficiente de b-jets (chorros de partículas inicializados a partir de la fragmentación de un quark b) con respecto a jets de otros sabores ha de aprovechar necesariamente las propiedades de producción y desintegración de los hadrones B. Dado que el objetivo del análisis es medir la sección eficaz de producción de quarks b en LHCb usando estados finales inclusivos con sabor b, también es indispensable la investigación de las correlaciones entre la producción del quark b y el correspondiente hadrón B, así como las correlaciones entre la pareja bb y la pareja resultante de hadrones B. Predicciones Monte Carlo (MC) permiten estimar como las propiedades del quark se modifican al pasar al nivel de hadrón por procesos como la fragmentación. Gracias a su particular función de fragmentación, el mesón B lleva gran parte de la energia del quark originado en la colisión primaria. Por lo tanto, el método aquí utilizado se espera que sea menos afectado por efectos no perturbativos que otras medidas basadas en canales de decaimiento exclusivos. El fondo del análisis consiste en una componente física, principalmente de jets de hadrones que derivan de la hadronización de quarks c y ligeros, y un fondo combinatorio, definido como los sucesos en que una pareja bb ha sido efectivamente producida y el algoritmo reconstruye jets no físicamente asociados a los quarks de señal. La parte combinatoria requiere una definición de jet para poderse estudiar. La herramienta de tagging desarrollada para identificar los jets provenientes de la hadronización del quark b es un algoritmo de jet de tipo cono: la idea básica es tomar un vértice inclusivo secundario procedentes de un hadrón B como seed (semilla) para la reconstrucción del jet. La posición del seed respecto al vértice primario (PV) establece la dirección de un cono de apertura dada. El jet se construye recogiendo las partículas cargadas y neutras que se encuentran en el interior del cono. Una ventaja de este método es el alta estadística que permite explorar correlaciones angulares entre las parejas bb y una región cinemática más grande en comparación con reconstrucciones exclusivas. Las trazas cargadas candidatas se seleccionan con requisitos sobre el impulso transverso, calidad de la reconstrucción de las trazas y significancia del parametro de impacto respecto al PV. La línea de vuelo de los hadrones B se reproduce con buena precisión por la posición del seed respecto al PV. Los jets se construyen sumando al quadrimomento del seed otras partículas cargadas y neutras que se encuentran dentro de un cono con el eje que coincide con la trayectoria del seed. Los requisitos para que los sucesos de señal MC sean acceptados preven la respuesta positiva de las lineas de trigger y de stripping seleccionadas para el análisis. Otros requisitos son la reconstrucción de exactamente un PV, y almenos un seed. Se han definido cortes fiduciales en la pseudorapidez eta y en el Pt de los jets, para garantizar la completa reconstrucción de los jets, así evitando inconstistencias infrarrojas en la aplicación de un algoritmo de tipo cono al fondo de quark y gluones. Una corrección de la energía es necesaria para tener en cuenta la pérdida de energía debido a partículas no detectadas o por medidas no correctas de la energía o del tracking. La idea aplicada ha sido calibrar la energía de los jets utilizando jets a nivel de generador Monte Carlo. El objetivo del análisis es calcular la sección eficaz de producción de parejas bb dentro del volumen fiducial (FV). Los datos analizados son los recogidos en el 2010 con colisiones a $\sqrt s = 7$ TeV. La eficiencia de selección tanto para la señal como para el fondo se ha determinado con las simulaciones MC. Las eficiencias de selección del fondo se han utilizado para estimar el número de sucesos de fondo esperados en una luminosidad igual a la de los datos analizados. Se ha utilizado este método debido a la falta de suficiente estadística MC que permitiera el ajuste de distribuciones de los datos y la extracción de las correspondientes fracciones de especies seleccionadas. La sección eficaz en el interval fiducial ha sido medida en 80.6 microbarns.
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34

Şamlı, Uğurcan. "Bistatic radar cross section synthesis for rectangular resistive sheets /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA319360.

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35

Ng, Hui-Siong. "Low energy (K§+, ¹²C) charge exchange cross section measurements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ60159.pdf.

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36

Weisberg, Adam. "A preliminary cross section measurement for K⁰*[Sigma]⁺ electroproduction." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1000211618.

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37

Leong, Lou Sai. "Fission fragment angular distribution and fission cross section validation." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00924483.

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The present knowledge of angular distributions of neutron-induced fission is limited to a maximal energy of 15 MeV, with large discrepancies around 14 MeV. Only 238U and 232Th have been investigated up to 100 MeV in a single experiment. The n_TOF Collaboration performed the fission cross section measurement of several actinides (232Th, 235U, 238U, 234U, 237Np) at the n_TOF facility using an experimental set-up made of Parallel Plate Avalanche Counters (PPAC), extending the energy domain of the incident neutron above hundreds of MeV. The method based on the detection of the 2 fragments in coincidence allowed to clearly disentangle the fission reactions among other types of reactions occurring in the spallation domain. I will show the methods we used to reconstruct the full angular resolution by the tracking of fission fragments. Below 10 MeV our results are consistent with existing data. For example in the case of 232Th, below 10 MeV the results show clearly the variation occurring at the first (1 MeV) and second (7 MeV) chance fission, corresponding to transition states of given J and K (total spin and its projection on the fission axis), and a much more accurate energy dependence at the 3rd chance threshold (14 MeV) has been obtained. In the spallation domain, above 30 MeV we confirm the high anisotropy revealed in 232Th by the single existing data set. I'll discuss the implications of this finding, related to the low anisotropy exhibited in proton-induced fission. I also explore the critical experiments which is valuable checks of nuclear data. The 237Np neutron-induced fission cross section has recently been measured in a large energy range (from eV to GeV) at the n TOF facility at CERN. When compared to previous measurements, the n TOF fission cross section appears to be higher by 5-7 % beyond the fission threshold. To check the relevance of n TOF data, we simulate a criticality experiment performed at Los Alamos with a 6 kg sphere of 237Np. This sphere was surrounded by enriched uranium 235U so as to approach criticality with fast neutrons. The simulation predicts a multiplication factor keff in better agreement with the experiment (the deviation of 750 pcm is reduced to 250 pcm) when we replace the ENDF/B- VII.0 evaluation of the 237Np fission cross section by the n TOF data. We also explore the hypothesis of deficiencies of the inelastic cross section in 235U which has been invoked by some authors to explain the deviation of 750 pcm. The large distortion that should be applied to the inelastic cross sections in order to reconcile the critical experiment with its simulation is incompatible with existing measurements. Also we show that the nubar of 237Np can hardly be incriminated because of the high accuracy of the existing data. Fission rate ratios or averaged fission cross sections measured in several fast neutron fields seem to give contradictory results on the validation of the 237Np cross section but at least one of the benchmark experiments, where the active deposits have been well calibrated for the number of atoms, favors the n TOF data set. These outcomes support the hypothesis of a higher fission cross section of 237Np.
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38

Karapinar, Banu Ozgen. "The geometry of yarn cross section in woven fabrics." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498960.

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39

Şamlı, Uğurcan. "Bistatic radar cross section synthesis for rectangular resistive sheets." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/8033.

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Approved for public release; distribution is unlimited
A method of moments solution for the bistatic scattering from planar resistive sheets is presented. The matrix scattering equations are inverted to obtain a rigorous inverse solution that can be applied to the synthesis of radar cross section. Computer calculations for several sheets demonstrate that the synthesized resistivity is in good agreement with the original resistivity.
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40

Bozhkov, Stanislav. "Idiosyncratic risk and the cross section of stock returns." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/16792.

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A key prediction of the Capital Asset Pricing Model (CAPM) is that idiosyncratic risk is not priced by investors because in the absence of frictions it can be fully diversified away. In the presence of constraints on diversification, refinements of the CAPM conclude that the part of idiosyncratic risk that is not diversified should be priced. Recent empirical studies yielded mixed evidence with some studies finding positive correlation between idiosyncratic risk and stock returns, while other studies reported none or even negative correlation. In this thesis we revisit the problem whether idiosyncratic risk is priced by the stock market and what the probable causes for the mixed evidence produced by other studies, using monthly data for the US market covering the period from 1980 until 2013. We find that one-period volatility forecasts are not significantly correlated with stock returns. On the other hand, the mean-reverting unconditional volatility is a robust predictor of returns. Consistent with economic theory, the size of the premium depends on the degree of 'knowledge' of the security among market participants. In particular, the premium for Nasdaq-traded stocks is higher than that for NYSE and Amex stocks. We also find stronger correlation between idiosyncratic risk and returns during recessions, which may suggest interaction of risk premium with decreased risk tolerance or other investment considerations like flight to safety or liquidity requirements. The difference between the correlations between the idiosyncratic volatility estimators used by other studies and the true risk metric - the mean-reverting volatility - is the likely cause for the mixed evidence produced by other studies. Our results are robust with respect to liquidity, momentum, return reversals, unadjusted price, liquidity, credit quality, omitted factors, and hold at daily frequency.
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41

Persson, Björn. "Assessment of Aircraft Radar Cross-Section for Detection Analysis." Doctoral thesis, Försvarshögskolan, Militärtekniska avdelningen (MTA), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-185214.

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Hiding from and surprising an opponent are tactics that have been used in warfare throughout history. They were features that aircraft originally possessed when they were first used in military operations. However, development of military technology is an endless struggle between advances in technology and counter technology. During World War II this struggle led to the development of a new technology called radar, which was designed to detect sea vessels and aircraft at a distance and deny them the element of surprise. This laid the foundation for modern air defenses and simultaneously created a need for aircraft to penetrate such defenses. Central to the tactics and technological development that followed from the deployment of radar on the modern battlefield is the radar cross-section (RCS) of aircraft, which dictates the range at which aircraft can be detected by radar. In this thesis some aspects of the RCS of aircraft in radar detection are investigated. A combination of experimental measurement of aircraft and digital model development of the RCS of aircraft has been used. From flight experiments, the uncertainty in aspect angle to a threat sensor, due to aircraft dynamics, is quantified for various aircraft. In addition, the RCS fluctuation behavior of a military jet trainer is investigated by dynamic in-flight measurement. The monostatic and bistatic RCS of an F-117 are modeled and findings show that spline interpolation provides superior accuracy when interpolating the RCS data. Smooth and conservative RCS models are suggested and a new RCS sampling scheme is presented. A model based on experimental data is suggested for determining the range of aspect angles that an aircraft is likely to orient towards a threat sensor, and experimental RCS data is compared to the classical Swerling radar target models. Possible consequences for military operations and the design of military systems are discussed and considerations for modeling the interaction between air defenses and aircraft penetrating those defenses are given.   This thesis should be of interest to military actors and the defense industry, since the analyses of the ability to detect aircraft using radar are important for military operations and their planning.
Att kunna gömma sig för att sedan överaska sin motståndare är en taktik som har använts inom krigsföring genom historien, detta var också en möjlighet flygplan erbjöd när de började användas i militära samanhang. Utveckling av teknik för militära ändamål är emellertid en ständigt pågående kamp mellan framsteg inom det befintliga teknikfältet och utveckling för att kunna motverka sådan teknik. Under andra världskriget ledde denna kamp till utvecklingen av radar, en teknik som används för att upptäcka och följa fartyg och flygplan på stora avstånd, vilket kraftigt försvårade möjlighet att överaska motståndaren med hjälp av flygplan. Utvecklingen av radar är en hörnsten inom moderna luftvärnssystem, vilket också har skapat ett behov för luftstridskrafter att kunna motverka och penetrera sådana skydd. Centralt för den teknik och taktikutveckling som skede till följd av att radar introducerades på det moderna slagfältet är flygplans radarmålarea, som är avgörande för på vilket avstånd det är möjligt att upptäcka flygplanet. I den här avhandlingen undersöks aspekter kring hur flygplans radarmålarea påverkar detektionsmöjligheterna för en hotradar. Avhandlingen består av både mätningar på faktiska flygplan samt forskning kring digitala modeller av radarmålarea. Flygförsöken gav kvantitativa exempel på hur stor osäkerhet i aspekt vinkel ett givet flygplan kan förväntas ha emot en hot sensor på grund av flygdynamik. Utöver detta så utfördes även en dynamisk mätning av radarmålarea på ett jetdrivet skolflygplan, för att undersöka fluktuationerna i radarmålarea. Både monostatisk och bistatisk radarmålarea har beräknats för en F-117 modell och resultaten tyder på att spline-interpolation ger den bästa noggrannheten vid interpolation. Vidare föreslås hur jämna och konservativa modeller av radarmålarea kan uppnås samt att en ny samplingsstrategi för radarmålarea presenteras. En modell som bygger på experimentell data föreslås för att uppskatta hur stor ändring av aspektvinkel ett givet flygplan kan förväntas ge emot en hotsensor, samt att mätdata av radarmålarea jämförs med de klassiska Swerling modellerna. Den påverkan resultaten förväntas ha på militära operationer och system diskuteras och några överväganden som bör beaktas vid modellering av interaktionen mellan flygplan och radar ges. Denna avhandling torde vara av intresse för såväl militära aktörer som försvarsindustri, eftersom analysen och möjligheten att upptäcka flygplan med radar är en viktig del av luftstrid och tillhörande planering.

QC 20160418

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42

Kermani, B. "Single cell box girder bridges of deformable cross-section." Thesis, University of Bristol, 1988. http://hdl.handle.net/1983/515e0dcd-3c7d-41d0-b8c9-e465ed073a51.

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43

Wong, Peter. "Two Essays on the Cross-Section of Stock Returns." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1364933300.

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44

Taute, Barend Jacobus Erasmus. "Envelope radar cross section analysis of faired composite bodies /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487595712159143.

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45

Tsappi, Philip. "Resistance heating of steel conductors of circular cross-section." Thesis, Aston University, 1987. http://publications.aston.ac.uk/8047/.

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The object of this thesis is to develop a method for calculating the losses developed in steel conductors of circular cross-section and at temperatures below 100oC, by the direct passage of a sinusoidally alternating current. Three cases are considered. 1. Isolated solid or tubular conductor. 2. Concentric arrangement of tube and solid return conductor. 3. Concentric arrangement of two tubes. These cases find applications in process temperature maintenance of pipelines, resistance heating of bars and design of bus-bars. The problems associated with the non-linearity of steel are examined. Resistance heating of bars and methods of surface heating of pipelines are briefly described. Magnetic-linear solutions based on Maxwell's equations are critically examined and conditions under which various formulae apply investigated. The conditions under which a tube is electrically equivalent to a solid conductor and to a semi-infinite plate are derived. Existing solutions for the calculation of losses in isolated steel conductors of circular cross-section are reviewed, evaluated and compared. Two methods of solution are developed for the three cases considered. The first is based on the magnetic-linear solutions and offers an alternative to the available methods which are not universal. The second solution extends the existing B/H step-function approximation method to small diameter conductors and to tubes in isolation or in a concentric arrangement. A comprehensive experimental investigation is presented for cases 1 and 2 above which confirms the validity of the proposed methods of solution. These are further supported by experimental results reported in the literature. Good agreement is obtained between measured and calculated loss values for surface field strengths beyond the linear part of the d.c. magnetisation characteristic. It is also shown that there is a difference in the electrical behaviour of a small diameter conductor or thin tube under resistance or induction heating conditions.
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46

Lyon, Jeffrey G. "FRP CONFINED REINFORCED CONCRETE CIRCULAR CROSS SECTION SEISMIC APPLICATIONS." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/149.

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In recent earthquakes, structures have not performed as well as expected resulting in a need for better means of retrofitting and improvements in seismic design. Fiber Reinforced Polymers (FRP), as a material with potential to increase strength and ductility of columns in conjunction with capacity design methodology, has promise for seismic design. By investigating the displacement, ductility, and flexural strength properties of FRP confined reinforced concrete circular cross sections, this study analyzes the seismic applications of FRP confinement. The study is performed by incorporating an FRP confined concrete stress-strain model into a developed Moment-Curvature and PM Interaction software. This software conducts a comparison between traditional steel and FRP confined sections while performing parameter studies on the 28-day unconfined concrete compressive strength, longitudinal reinforcing ratio, cross section diameter, FRP confinement jacket thickness-cross section diameter ratio, and FRP confinement system design variables. These studies validate FRP’s performance for seismic applications resulting in several design recommendations to increase displacement capacity, ductility, and flexural strength and, thus, seismic performance.
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47

Riccio, Ciro. "Mesure du flux et de la section efficace des antineutrinos dans le détecteur proche de l'expérience T2K." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS013/document.

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T2K (Tokai to Kamioka) est une expérience d’oscillation de neutrinos muoniques sur une longue ligne de base, située au Japon. Elle est conçue pour mesurer le changement de saveur des neutrinos d’un faisceau produit à l’aide d’un accélérateur au laboratoire JPARC de Tokai. Les détecteurs proche et lointain sont placés légèrement hors axe par rapport au faisceau. Depuis la découverte en 2013 de l’apparition de neutrinos électroniques, T2K a inversé la polarité des cornes magnétiques intervenant dans la production du faisceau, afin de produire un faisceau d’antineutrinos et d’augmenter la sensibilité de l’expérience à la violation de la charge-parité dans le secteur leptonique. Le faisceau produit est alors dominé par les antineutrinos muoniques avec une composante mesurable de neutrinos muoniques. L’analyse simultanée, dans les données prises avec le faisceau de neutrinos et le faisceau d’antineutrinos, des interactions par courant chargé dans le détecteur proche ND280, permet de réduire l’impact sur les analyses d’oscillation des incertitudes liées au flux de (anti)neutrinos et à leur section efficace d’interaction. Les données de ND280 permettent également de mesurer les sections efficaces d’interaction des antineutrinos d’énergie proche de 600 MeV. La bonne connaissance du processus d’interaction des (anti)neutrinos avec les noyaux atomiques est cruciale pour interpréter les résultats de l’expérience en termes d’oscillations. De nombreux modèles théoriques ont été développés pour décrire les effets nucléaires lors des interactions des (anti)neutrinos, mais une vison globale cohérente n’a pas encore émergé. En particulier, des mesures variées de section efficace d’interaction par courant chargé sans production de pion dans l’état final suggèrent la possibilité pour les neutrinos d’interagir avec des paires de nucléons corrélés, entrainant l’éjection de plus d’un nucleon hors du noyau (composante dite “multi-nucléon”). Divers modèles ont proposé des estimations différentes de ce processus et une mesure précise et sans ambiguité n’est pas encore disponible. Ce travail de thèse se concentre sur trois études. La première détaille la sélection des interactions de neutrinos muoniques par courant chargé dans le détecteur proche hors axe. Dans un premier temps l’échantillon de données était divisé en deux selon le nombre de traces chargées de l’événement, puis l’accumulation de davantage de données a permis la séparation de l’échantillon en trois lots selon le contenu en pions de l’événement. La seconde étude consiste en la mesure simultanée de la section efficace d’interaction des neutrinos et des antineutrinos muoniques par courant chargé, conduisant à un état final sans pion mesuré dans le détecteur ND280. Ces sections efficaces sont extraites en fonction de l’impulsion et de l’angle du muon issu de l’interaction, permettant ainsi d’évaluer la somme, la différence et l’asymétrie entre les sections efficaces des neutrinos et des antineutrinos. La somme permet d’isoler la composante d’interférence vecteur-axial de la section efficace, et la différence est sensible à la composante multi-nucléons. L’asymétrie permet d’estimer directement le biais éventuel sur la mesure de la phase de violation de CP dû à la modélisation des sections efficaces, dans l’analyse d’oscillation de neutrinos. La dernière partie de la thèse étudie la proposition d’utiliser la technologie dite de multi-PMT pour le detector Hyper-Kamiokande, version à plus grande échelle de Super-Kamiokande, ainsi que la possibilité d’étudier le flux de neutrinos avec un détecteur basé sur le rayonnement Cherenkov dans l’eau, et placé à environ 2 km de l’origine du faisceau de neutrinos. Un multi-PMT est une sphère de plastique contenant 26 tubes photomultiplicateurs, qui pourrait améliorer l’efficacité des futurs détecteurs basés sur le rayonnement Cherenkov dans l’eau
T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment installed in Japan and designed to measure neutrino flavor oscillation using an off-axis neutrino beam produced at the J-PARC accelerator facility in Tokai. Since its discovery of electron neutrino appearance in 2013, T2K has switched its beam magnet polarities to run in antineutrino beam mode in order to enhance its sensitivity to the charge-parity violation in the leptonic sector. The beam is dominated by muon antineutrinos, but it also contains a sizable contamination from muon neutrinos. The analysis of both neutrino and antineutrino charged-current interactions in the off-axis near detector ND280, provides a significant reduction of the flux prediction and cross-section modeling systematic uncertainties in the oscillation analysis. ND280 data also gives us the opportunity to measure antineutrinos cross-sections at the energy around 600 MeV. Information on (anti)neutrino scattering is vital for the interpretation of neutrino oscillation. Many theoretical models have been developed to describe the nuclear effects in (anti)neutrino scattering, but a consistent picture has yet to emerge. In particular, various measurements of charged-current cross-section without production of pions in the final state have suggested the presence of another channel where neutrinos interact with pairs of correlated nucleons and more than one nucleon is knocked-out from the nucleus (multi-nucleon component). Various models have proposed different estimations of such process and a precise and unambiguous measurement is not yet available. This thesis work is focused on three different arguments. First the selections of CC interactions of muon neutrinos in antineutrino beam in the off-axis near detector. In a first iteration this sample has been divided into two sub-sample based on the track multiplicity, then with more statistic a separation into three sub-samples based on the pion content in each event was possible. Then on the simultaneous measurement of the double-differential muon neutrino and antineutrino charged-current cross-section without pions in the final state using the off-axis near detector. The neutrino and antineutrino cross-sections will be simultaneously extracted as a function of muon momentum and angle with a likelihood fit, including proper estimation of the correlations, allowing the evaluation of the sum, difference and asymmetry between the two cross-sections. The sum isolates the axial-vector interference term of the cross-section, and the difference enhances the sensitivity to the multinucleon component. The asymmetry is a direct estimation on any possible bias due to mismodeling of (anti)neutrino interactions on the measurement of the CP violation phase in neutrino oscillation. The last topic concerns the proposal of the multi-PMT technology as detector for Hyper-Kamiokande, the upgrade of Super-Kamiokande, and the intermediate water v Cherenkov proposed to study the neutrino flux at ~2 $km$ from the beam production point. A multi-PMT is a plastic sphere filled with 26 photomultiplier tube that could improve the efficiency of the Cherenkov detectors foreseen in the future
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48

Botes, Danniëll. "Few group cross section representation based on sparse grid methods / Danniëll Botes." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8845.

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This thesis addresses the problem of representing few group, homogenised neutron cross sections as a function of state parameters (e.g. burn-up, fuel and moderator temperature, etc.) that describe the conditions in the reactor. The problem is multi-dimensional and the cross section samples, required for building the representation, are the result of expensive transport calculations. At the same time, practical applications require high accuracy. The representation method must therefore be efficient in terms of the number of samples needed for constructing the representation, storage requirements and cross section reconstruction time. Sparse grid methods are proposed for constructing such an efficient representation. Approximation through quasi-regression as well as polynomial interpolation, both based on sparse grids, were investigated. These methods have built-in error estimation capabilities and methods for optimising the representation, and scale well with the number of state parameters. An anisotropic sparse grid integrator based on Clenshaw-Curtis quadrature was implemented, verified and coupled to a pre-existing cross section representation system. Some ways to improve the integrator’s performance were also explored. The sparse grid methods were used to construct cross section representations for various Light Water Reactor fuel assemblies. These reactors have different operating conditions, enrichments and state parameters and therefore pose different challenges to a representation method. Additionally, an example where the cross sections have a different group structure, and were calculated using a different transport code, was used to test the representation method. The built-in error measures were tested on independent, uniformly distributed, quasi-random sample points. In all the cases studied, interpolation proved to be more accurate than approximation for the same number of samples. The primary source of error was found to be the Xenon transient at the beginning of an element’s life (BOL). To address this, the domain was split along the burn-up dimension into “start-up” and “operating” representations. As an alternative, the Xenon concentration was set to its equilibrium value for the whole burn-up range. The representations were also improved by applying anisotropic sampling. It was concluded that interpolation on a sparse grid shows promise as a method for building a cross section representation of sufficient accuracy to be used for practical reactor calculations with a reasonable number of samples.
Thesis (MSc Engineering Sciences (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013.
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Dhakal, Sushil. "Study of DD Neutrons and their Transmission in Iron Spheres." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1478097309006943.

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50

Mack, Gregory D. "Constraining the Particle Nature of Dark Matter: Model-independent Tests From the Intersection of Theory and Observation." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211486940.

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