Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 61 for “"tree-level"”.
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Tree-Level Forest Monitoring with Artificial Intelligence Using Neural Networks and High-Resolution Imagery
Mapping and monitoring tree crowns provides vital information on the earth's changing climate. We can use tree measurements to quantify the biomass and stored carbon in a forest, we can use those measurements to inform plantation management on harvest cycles, we can even use tree measurements to …
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Response of uneven-aged in interior Douglas-fir stands to precommercial thinning in central interior, British Columbia
… Analyses were performed at both the stand and tree level. The growth of basal area per ha, quadratic mean dbh, volume per ha and Lorey’s height were used for stand level analyses. At the tree level, dbh, height, basal area and volume were the variables of interest. At the stand level, mortality …
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Cosmological constraints using 2- and 3-point correlations with meerkat, the ska and other surveys
We explore the information from HI power spectra (tree-level and one-loop) in redshift space and bispectrum tree-level models. 21-cm emission from neutral hydrogen is a promising tool for probing the matter distribution in the universe post-reionization. The HI signals contain signatures of the …
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Celestial Chiral Algebras and Self-Dual Gravity
… been the insight that this duality is true at tree-level which led to the discovery of new infinite dimensional symmetry algebras of tree-level amplitudes in flat space closely related to $w_{1+\infty}$. This thesis studies these celestial chiral algebras in the light of twistor theory and …
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QCD jet evolution at high and low scales
… in validating the CKKW approach for merging tree-level matrix elements and parton showers. In the second part the main project is documented comprising the definition, realization and verification of a new QCD colour-dipole cascade. Finally, a new cluster-hadronization model is introduced.
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Ecological Factors Influencing Infection Rates of the Birch Polypore Inonotus obliquus in the Laurentian Mixed Forest Province
… to birch (<em>Betula </em>spp<em>.</em>) trees in northern hardwood forests around the world, has been harvested intensively in recent years for its potentially medicinal properties. However, there is a dearth of ecological understanding of this fungus; even basic infection rates tend to …
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Monte-Carlo event generation for the LHC
… parton-shower emissions with the help of exact tree-level matrix elements is revisited and significantly improved as attested by first results. In a next step, an automated implementation of the POWHEG method is presented. It allows for the combination of parton showers with full next-to-leading …
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The KLT relations in unimodular gravity
… In particular, we show, up to five-points and tree-level, that the KLT relations of perturbative gravity hold for trace free or unimodular gravity. This work is in conjunction with a paper written with A. Welman, J. Murugan and G.F.R. Ellis (ARXIV: 1511.08517)
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Modeling Endemic Bark Beetle Populations in Southwestern Ponderosa Pine Forests
… populations phase between epidemic, outbreak levels, and low population density, endemic levels. The majority of scientific research is focused on outbreak populations because of the associated economic, ecological, and social impacts. Endemic populations are rarely studied but could provide …
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Causality and unitarity in the early universe
… UV/IR sum rules are derived and validated with a tree-level exchange example. Chapter 5 develops causality-based cutting rules that break loop integrands into tree-level discontinuities, streamlining cosmological computations. These rules lead to the cosmological KLN theorem, ensuring the absence …
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Pion electromagnetic form factor in the Kroll-Lee-Zumino model at zero and finite temperature
… radius are found to improve greatly over the tree level result, and are in good agreement with the experimental data. A calculation of the vertex and self energy functions in the Matsubara formalism at finite temperature do not agree with the results of the Gale & Kapusta calculations. The …
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Ecological-Hydrological Feedback in Forested Wetlands
… the biotic and abiotic consequences of water level variability is not well understood. The effects of flooding on carbon and water exchanges are important knowledge gaps where progress could benefit management of natural resources and predicting of changes in surface geophysical cycles. Two …
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2D Chiral Algebras from Koszul Duality & Associativity
… collinear splitting functions not just at tree-level but to arbitrary loop order. To apply this technique, and indeed for the celestial chiral algebra to exist, the corresponding 4d massless theory must admit a local gauge-anomaly-free lift to twistor space. We will also use Koszul duality …
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Rho-Meson propagator at two-loop order in the Kroll-Lee-Zumino quantum field theory
… a framework to compute corrections to the tree-level Vector-Meson-Dominance model. Despite a large ρππ coupling (gρππ ≈ 5), the loop suppresion factor of 1=(4π)² helps give reasonably small NLO (one-loop) corrections. When it comes to describing hadronic physics, one might say, these …
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Keanekaragaman mangrove di Pantai Kecamatan Panggungrejo Kota Pasuruan
… the coast. At each transect plot made for the tree level with size 20 x 20 cm, and 10 x 10 for small trees, 5 x 5 and 2 x 2 stakes for Seedlings. The results showed that, there are 9 species belonging to the genus 7 and 5 families were found on the beach Panggungrejo Pasuruan district. …
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Études in Ambitwistor Strings - Exploring new models, higher loops and curved backgrounds
… refined 4d scattering equations. It computes all tree level amplitudes, in all trace sectors, of minimally coupled sEYM with one gluon multiplet and two, CP conjugate, gravity multiplets. The RSV formula for \Neqfour super-Yang-Mills and a certain subsector of the CS formula for \Neqeight …
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Effective field theory of the electroweak sector
… here yield more accurate bounds on loop-level operator coefficients. I finish with a global analysis of the full set of nine operators. Bounds are presented on the linearly-independent combinations of the operators. The four operators which affect precision electroweak observables at …
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The Runny Gauge Plasma: shear viscosity to entropy for quarks and gluons
… in perturbation theory as loop corrections to tree level amplitudes, and describe both the scale-dependence of the coupling and charge screening in a many- body system. We emphasise that because the effective interaction strength, for a QGP, may vary considerably at the relevant scales, the …
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Object oriented approach to genetic programming
… To solve this problem we propose a so called tree-level system which is able to automatically generate a large number of strategies from a set of primitive functions
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Spatio-temporal optimization of tree removal to efficiently minimize crown fire potential
… containing a large number of stands. Stand-level thinning prescriptions have thus limitations when applied for reducing the risk of high-intensity wildfires. They use indicators of crown fire potential (e.g., canopy base height and canopy bulk density) that ignore variability of fuels within …
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