58 research outputs found
The fire resistance of high-strength concrete containing natural zeolites
No full textMore sustainable and environmentally friendly concretes are essential to reduce the climatic and environmental impact of the growing demand for concrete to fuel urban sprawl. This manuscript reports on an experimental study designed to test the fire resistance of one such concrete, prepared to contain natural zeolite-bearing tuff. The fire resistance of concretes containing natural zeolites has received little attention and is therefore poorly understood. Relative reductions in residual uniaxial compressive strength as a function of increasing temperature (up to 1000 °C) were very similar for the reference concrete (containing no tuff) and the tuff-bearing concrete. These data can be explained by the similar influence of high-temperature on the chemical (dehydroxylation reactions) and physical (microcracking and porosity) properties of both concretes. The satisfactory performance of the concrete containing natural zeolites following fire is welcome owing to the economic, climatic, and environmental benefits of using natural pozzolan and aggregate substitutes
Alteration-Induced Volcano Instability at La Soufrière de Guadeloupe (Eastern Caribbean)
No full textVolcanoes are unstable structures that deform laterally and frequently experience mass wasting events. Hydrothermal alteration is often invoked as a mechanism that contributes significantly to volcano instability. We present a study that combines laboratory experiments, geophysical data, and large-scale numerical modeling to better understand the influence of alteration on volcano stability, using La Soufrière de Guadeloupe (Eastern Caribbean) as a case study. Laboratory experiments on variably altered (advanced argillic alteration) blocks show that uniaxial compressive strength, Young's modulus, and cohesion decrease as a function of increasing alteration, but that the internal friction angle does not change systematically. Simplified volcano cross sections were prepared (a homogenous volcano, a volcano containing the alteration zone identified by a recent electrical survey, and a volcano with an artificially enlarged area of alteration) and mechanical properties were assigned to zones corresponding to unaltered and altered rock. Numerical modeling performed on these cross sections, using a hydro-thermo-mechanical modeling code, show (a) the importance of using upscaled values in large-scale models and (b) that alteration significantly increases volcano deformation and collapse volume. Finally, we combined published muon tomography data with our laboratory data to create a 3D strength map, exposing a low-strength zone beneath the southern flank of the volcano coincident with the hydrothermal system. We conclude that hydrothermal alteration decreases volcano stability and thus expedites volcano spreading and increases the likelihood of mass wasting events and associated volcanic hazards. Hydrothermal alteration, and its evolution, should therefore be monitored at active volcanoes worldwide
The chirality-flow formalism for the standard model
No full textIn a recent paper we introduced the chirality-flow formalism, a method for
simple and transparent calculations of Feynman diagrams based on the left- and
right-chiral nature of spacetime. While our
previous work focused on massless QED and QCD at tree-level, we here extend the
chirality-flow formalism to the full (tree-level) Standard Model, including
massive particles and electroweak interactions -- for which the -interaction
simplifies elegantly due to its chiral nature. We illustrate how values of
Feynman diagrams can be immediately written down with some representative
examples.Comment: 35 pages, published version with fixed missing factor of 1/\sqrt{2}
in VVV vertex in table
Elemente der Trigonometrie mit ihrer Anwendung in der mathematischen Geographie : als Lehrbuch für den Unterricht und zum Selbststudium
No full textentworfen von C. G. ReuschleGeschenkexlibris-Etikette: "Legat von Herrn Professor Joh. Orelli" 002193044_0002 Exemplar der ETH-BI
Einladungs-Schrift zu der Feier des Geburtsfestes ... des Königs Wilhelm von Würtemberg im Königl. Gymnasium zu Stuttgart am 27. September 1840
No full textAnalytische Theorie der Bewegung des sphärischen Pendels von C. G. Reuschl
Decomposition of one-loop QCD amplitudes into primitive amplitudes based on shuffle relations
No full textThe chirality-flow formalism
No full textWe take a fresh look at Feynman diagrams in the spinor-helicity formalism. Focusing on tree-level massless QED and QCD, we develop a new and conceptually simple graphical method for their calculation. In this pictorial method, which we dub the chirality-flow formalism, Feynman diagrams are directly represented in terms of chirality-flow lines corresponding to spinor inner products, without the need to resort to intermediate algebraic manipulations
Parton Shower and Matching Uncertainties in Top Quark Pair Production with Herwig 7
No full textWe evaluate the theoretical uncertainties in next-to-leading order plus parton shower predictions for top quark pair production and decay in hadronic collisions. Our work is carried out using the Herwig 7 event generator and presents an in-depth study of variations in matching schemes with two systematically different shower algorithms, the traditional angular-ordered and alternative dipole shower. We also present all of the required extensions of the Herwig dipole shower algorithm to properly take into account quark mass effects, as well as its ability to perform top quark decays. The predictions are compared at parton level as well as to Large Hadron Collider data, including in the boosted regime. We find that the regions where predictions with a non-top-quark-specific tune differ drastically from data are plagued by large uncertainties which are consistent between our two shower and matching algorithms.We evaluate the theoretical uncertainties in next-to-leading order plus parton shower predictions for top quark pair production and decay in hadronic collisions. Our work is carried out using the Herwig 7 event generator and presents an in-depth study of variations in matching schemes with two systematically different shower algorithms, the traditional angular-ordered and alternative dipole shower. We also present all of the required extensions of the Herwig dipole shower algorithm to properly take into account quark mass effects, as well as its ability to perform top quark decays. The predictions are compared at parton level as well as to LHC data, including in the boosted regime. We find that the regions where predictions with a non-top-quark-specific tune differ drastically from data are plagued by large uncertainties which are consistent between our two shower and matching algorithms
Correlation of microseismic and chemical properties of brittle deformation in Locharbriggs sandstone
No full textThe time-dependent properties of ceramic materials such as rocks depend both on preexisting cracks and chemical properties acting at their tips. We have examined the direct effect of chemical processes on the growth of a crack population by carrying out triaxial flow-through compression tests on Locharbriggs sandstone. The tests were carried out at temperatures of 25–80°C and at strain rates ranging from 10−5 to 10−8 s−1 under constant stress rate loading. The exit pore fluid was analyzed after the tests for the concentration of dissolved ions and acoustic emission was monitored in real time throughout the tests. The exit pore fluid silica concentration and microcrack damage derived from the acoustic emission (AE) data both exhibited an exponential increase during the strain hardening phase of deformation. Damage parameters inferred from the AE data predict the stress-strain curves adequately, or at least up to the point of strong microcrack coalescence. The damage parameters and silica signal were strongly correlated by a power law relationship. The observed environment and strain rate dependence of mechanical properties can hence be attributed uniquely to time-dependent crack growth by the stress corrosion mechanism
Electroweak and QCD corrections to Z -boson production with one b jet in a massive five-flavor scheme
No full textWe compute the O(αsα2) and O(αs2α) contributions to the production cross section of a Z boson with one b jet at the Large Hadron Collider (LHC) and study their phenomenological relevance for LHC physics. The accurate prediction of hadronic Z+b-jet production is needed to control a background that greatly affects both the measurement of Higgs-boson properties and the searches of new physics at the LHC. At the same time it could enable the first precise measurement of the b-quark parton distribution function. In this context b-quark mass effects become relevant and need to be studied with care, both at the level of the hard process and at the level of the initial- and final-state parton evolution. It is the aim of this paper to explore some of these issues in the framework of a massive five-flavor scheme and to assess the need for the inclusion of both electroweak corrections, in addition to QCD corrections, and b-quark mass effects in the prediction of total and differential cross sections for hadronic Z+b-jet production
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