1,878 research outputs found

    Drilling Fluids for Deepwater Fields: An Overview

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    The increasing oil demand around the world along with the depletion of onshore and shallow water oil reserves have forced the oil companies moving into the development of deepwater subsea hydrocarbon reservoirs. Drilling fluids play a key role in all drilling operations, but they get a greater relevance in deepwater environments where the technological challenges of drilling at these extreme conditions generate significant operational risks as well as very high costs during the development of this kind of fields. The operational issues and concerns related to the drilling fluid design and application for deepwater fields are generally well known: narrow pore/fracture pressure gradient margins, wellbore stability, clay swelling, gas hydrates formation, formation damage, salt formations, lost circulation, stuck pipe, cuttings transport and environmental and safety aspects. Therefore, the present chapter aims to give an overview on the main challenges and research related to drilling fluid design and application for deepwater fields through the revision of the state of the art of the current and innovative technological solutions reported in literature

    A construção de um programa Python para o ensino da transfêrencia da órbita de Hohmann

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    This study presents a simulation in python created as a didactic tool for studyingcelestial mechanics. The program that runs the simulation is designed for studentsto visualize all possible orbital trajectories, as well as to understand the transferorbits’ principal characteristics using as an example the journey of a spaceship from Earth to Mars and Jupiter. Additionally, the program can be used todetermine the principal characteristics of the planetary orbits. In addition, theprogram can relate elliptical parameters to energy and angular momentum ofthe planets, and to Kepler´s Laws.En este estudio se presenta una simulación realizada en python como herramientadidáctica para la enseñanza de la mecánica celeste. El programa que hace lasimulación se diseñó para que los estudiantes de cursos introductorios de astronomíavisualicen las posibles trayectorias y comprendan las características principalesde transferencias orbitales usando como ejemplo el viaje de una nave espacialde la Tierra a Marte y a Júpiter. Se encuentra que el programa también puedeutilizarse para determinar las características principales de las órbitas planetariasy relacionar los parámetros de las elipses con la energía y el momentum angularde los planetas, y en general con las leyes de Kepler.Neste artigo é apresentada uma simulação feita no Python como um recurso didático para oensino da mecânica celeste. O programa da simulação foi feito pra que os estudantes dos cursosintrodutórios de astronomia possam ter a visualização das possíveis trajetórias e compreendamas características principais de transferências orbitais usando como exemplo a viagem de umanave espacial da Terra a Marte e a Júpiter. O programa também pode ser usado para determinaras principais características das órbitas planetárias e relacionar os parâmetros das elipses comenergia e momento angular dos planetas, e em geral com as leis de Kepler

    México y Jalisco en la coyuntura: segundo semestre de 1997

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    Análisis de coyuntura sobre los principales sucesos del segundo semestre de 1997 en Jalisco, a nivel político, económico y social: la transición política y las elecciones locales de noviembre de ese año, el impacto en México de la crisis de las economías asiáticas, el tema de la inseguridad pública y la cuestión de Chiapas.ITESO, A.C

    Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

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    The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of ttt\overline{t}, W+bbW+b\overline{b} and W+ccW+c\overline{c} is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ±\pm 0.02 \mbox{fb}^{-1}. The WW bosons are reconstructed in the decays WνW\rightarrow\ell\nu, where \ell denotes muon or electron, while the bb and cc quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

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    A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

    Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

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    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV
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