Simulação numérica para otimização de um motor de baixa cilindrada para competição de eficiência energética

TCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia Automotiva.O aquecimento global é um dos maiores problemas que a sociedade moderna está enfrentando, e a fonte de energia mais utilizada nos veículos de hoje, os combustíveis nos motores de combustão interna, são um dos maiores vilões. Este assunto tem sido amplamente discutido por agências governamentais, instituições de pesquisa e pela indústria, pressionando-as a encontrar soluções, desenvolvendo motores mais limpos e mais eficientes. Visando essas soluções, a Shell Oil Company criou a competição Shell Eco Marathon (SEM) para incentivar os estudantes universitários a projetar e construir alguns dos protótipos veiculares mais eficientes do mundo, com base nas matrizes energéticas existentes. Neste trabalho, ao combinar a análise computacional, usando AVL-BOOST, com uma ferramenta de melhoria contínua (Design of Experiments - DOE), foi realizado um estudo de otimização de motores. Para este fim, foi utilizado um motor de combustão interna de um cilindro, de 35,8cc e 1,4hp, de ignição por faísca, usado pela equipe EFICEM/CTJ/UFSC na Shell Eco-Marathon. A simulação numérica requer a alimentação do programa com os parâmetros geométricos e de operação do motor e, usando DOE para alternar alguns desses parâmetros, tais como razão de compressão, geometria e tamanho da tubulação, tempo de válvula e avanço da ignição, tornou possível determinar o melhor desempenho possível do motor comparando o resultado com os dados obtidos da documentação técnica do motor, bem como as curvas de operação de potência e torque para a validação e otimização do modelo. Os modelos de transferência de calor utilizados em tubulações e cilindros, assim como o modelo de combustão, foram escolhidos com base na revisão da literatura. Dependendo do parâmetro explorado do motor, foi possível obter melhorias na faixa de 11% a 26% no consumo específico de combustível, potência e torque.Global warming is one of the major problems that modern society is facing, and the most widely used energy source in vehicles today, the fuels in the internal combustion engines, are one of the biggest villains. This matter has been discussed widely by government agencies, research institutions, and the industry, pressing them to find solutions, developing cleaner and more efficient engines. Aiming at these solutions, Shell Oil Company created the Shell Eco Marathon (SEM) competition to encourage university students to design and build some of the world’s most efficient vehicular prototypes based on the existing energy matrices. In this work, while combining computational analysis, using AVL-BOOST, with a continuous improvement tool (Design of Experiments - DOE), an engine optimization study was performed. For this purpose, a single-cylinder, 35,8cc, 1,4hp, spark-ignition internal combustion engine, used by the EFICEM/CTJ/UFSC at the Shell Eco-Marathon, was used. The numerical simulation requires to feed the software with the engine’s geometric and operation parameters and, using DOE to alternate some of these parameters such as compression ratio, pipeline geometry and size, valve timing, and spark advance made it possible to determine the best possible engine performance comparing the result with data obtained from the engine’s technical documentation as well as the power and torque operation curves for the model validation and optimization. The heat transfer models used in pipelines and cylinders, as well as the combustion model, were chosen based on the literature review. Depending on the explored engine parameter, it was possible to obtain improvements in the range of 11% to 26% in the specific fuel consumption, power and torque

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

Peer reviewe

Strategies and performance of the CMS silicon tracker alignment during LHC Run 2

The strategies for and the performance of the CMS silicon tracking system alignment during the 2015–2018 data-taking period of the LHC are described. The alignment procedures during and after data taking are explained. Alignment scenarios are also derived for use in the simulation of the detector response. Systematic effects, related to intrinsic symmetries of the alignment task or to external constraints, are discussed and illustrated for different scenarios

Inclusive nonresonant multilepton probes of new phenomena at s\sqrt{s} = 13 TeV

An inclusive search for nonresonant signatures of beyond the standard model (SM) phenomena in events with three or more charged leptons, including hadronically decaying $\tau$ leptons, is presented. The analysis is based on a data sample corresponding to an integrated luminosity of 138 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}$ = 13 TeV, collected by the CMS experiment at the LHC in 2016-2018. Events are categorized based on the lepton and b-tagged jet multiplicities and various kinematic variables. Three scenarios of physics beyond the SM are probed, and signal-specific boosted decision trees are used for enhancing sensitivity. No significant deviations from the background expectations are observed. Lower limits are set at 95% confidence level on the mass of type-III seesaw heavy fermions in the range 845-1065 GeV for various decay branching fraction combinations to SM leptons. Doublet and singlet vector-like $\tau$ lepton extensions of the SM are excluded for masses below 1045 GeV and in the mass range 125-150 GeV, respectively. Scalar leptoquarks decaying exclusively to a top quark and a lepton are excluded below 1.12-1.42 TeV, depending on the lepton flavor. For the type-III seesaw as well as the vector-like doublet model, these constraints are the most stringent to date. For the vector-like singlet model, these are the first constraints from the LHC experiments. Detailed results are also presented to facilitate alternative theoretical interpretations

Inclusive nonresonant multilepton probes of new phenomena at s\sqrt{s} = 13 TeV

An inclusive search for nonresonant signatures of beyond the standard model (SM) phenomena in events with three or more charged leptons, including hadronically decaying $\tau$ leptons, is presented. The analysis is based on a data sample corresponding to an integrated luminosity of 138 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}$ = 13 TeV, collected by the CMS experiment at the LHC in 2016-2018. Events are categorized based on the lepton and b-tagged jet multiplicities and various kinematic variables. Three scenarios of physics beyond the SM are probed, and signal-specific boosted decision trees are used for enhancing sensitivity. No significant deviations from the background expectations are observed. Lower limits are set at 95% confidence level on the mass of type-III seesaw heavy fermions in the range 845-1065 GeV for various decay branching fraction combinations to SM leptons. Doublet and singlet vector-like $\tau$ lepton extensions of the SM are excluded for masses below 1045 GeV and in the mass range 125-150 GeV, respectively. Scalar leptoquarks decaying exclusively to a top quark and a lepton are excluded below 1.12-1.42 TeV, depending on the lepton flavor. For the type-III seesaw as well as the vector-like doublet model, these constraints are the most stringent to date. For the vector-like singlet model, these are the first constraints from the LHC experiments. Detailed results are also presented to facilitate alternative theoretical interpretations

Observation of triple J/ψ\psi meson production in proton-proton collisions at s\sqrt{s} = 13 TeV

The first observation of the simultaneous production of three J/$\psi$ mesons in proton-proton (pp) collisions is presented, based on a data sample collected by the CMS experiment at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 133 fb$^{-1}$. The pp $\to$ J/$\psi\,$J/$\psi\,$J/$\psi\,$X process is observed with a significance above five standard deviations in final states with three $\mu^+\mu^-$ pairs. The measured inclusive fiducial cross section of $\sigma$(pp $\to$ J/$\psi\,$J/$\psi\,$J/$\psi\,$X)= 272$^{+141}_{-104}$ (stat) $\pm$ 17 (syst) fb is compared to theoretical expectations for the production of three J/$\psi$ mesons in single- (SPS), double- (DPS), and triple- (TPS) parton scatterings. Assuming factorization of multiple hard-scattering probabilities in terms of SPS cross sections, the measured process is found to be dominated by DPS and TPS contributions, and an effective DPS cross section, related to the transverse distribution of partons in the proton, of $\sigma_\mathrm{eff,DPS}$ = 2.7$^{+1.4}_{-1.0}$ (exp) ${}^{+1.5}_{-1.0}$ (theo) mb is determined

Evidence for WW/WZ vector boson scattering in the decay channel ℓν\ell\nuqq produced in association with two jets in proton-proton collisions at s\sqrt{s} = 13 TeV

Evidence is reported for electroweak (EW) vector boson scattering in the decay channel $\ell\nu$qq of two weak vector bosons WV (V = W or Z), produced in association with two parton jets. The search uses a data set of proton-proton collisions at 13 TeV collected with the CMS detector during 2016-2018 with an integrated luminosity of 138 fb$^{-1}$. Events are selected requiring one lepton (electron or muon), moderate missing transverse momentum, two jets with a large pseudorapidity separation and a large dijet invariant mass, and a signature consistent with the hadronic decay of a W/Z boson. The cross section is computed in a fiducial phase space defined at parton level requiring all parton transverse momenta $p_\mathrm{T} \gt$ 10 GeV and at least one pair of outgoing partons with invariant mass $m_\mathrm{qq}\gt$ 100 GeV. The measured and expected EW WV production cross sections are 1.90$^{+0.53}_{-0.46}$ pb and 2.23$^{+0.08}_{-0.11}$ (scale) $\pm$ 0.05(PDF) pb, respectively, where PDF is the parton distribution function. The observed EW signal strength is $m_\mathrm{EW}$ = 0.85 $pm$ 0.12 (stat)$^{+0.19}_{-0.17}$ (syst), corresponding to a signal significance of 4.4 standard deviations with 5.1 expected. This is the first evidence of vector boson scattering in the $\ell\nu$qq decay channel at LHC. The simultaneous measurement of the EW and quantum chromodynamics associated diboson production agrees with the standard model prediction

Development of the CMS detector for the CERN LHC Run 3

International audienceSince the initial data taking of the CERN LHC, the CMS experiment has undergone substantial upgrades and improvements. This paper discusses the CMS detector as it is configured for the third data-taking period of the CERN LHC, Run 3, which started in 2022. The entire silicon pixel tracking detector was replaced. A new powering system for the superconducting solenoid was installed. The electronics of the hadron calorimeter was upgraded. All the muon electronic systems were upgraded, and new muon detector stations were added, including a gas electron multiplier detector. The precision proton spectrometer was upgraded. The dedicated luminosity detectors and the beam loss monitor were refurbished. Substantial improvements to the trigger, data acquisition, software, and computing systems were also implemented, including a new hybrid CPU/GPU farm for the high-level trigger

Measurement and QCD analysis of double-differential inclusive jet cross sections in proton-proton collisions at s \sqrt{s} = 13 TeV

International audienceA measurement of the inclusive jet production in proton-proton collisions at the LHC at $\sqrt{s}$ = 13 TeV is presented. The double-differential cross sections are measured as a function of the jet transverse momentum p$_{T}$ and the absolute jet rapidity |y|. The anti-k$_{T}$ clustering algorithm is used with distance parameter of 0.4 (0.7) in a phase space region with jet p$_{T}$ from 97 GeV up to 3.1 TeV and |y| < 2.0. Data collected with the CMS detector are used, corresponding to an integrated luminosity of 36.3 fb$^{−1}$ (33.5 fb$^{−1}$). The measurement is used in a comprehensive QCD analysis at next-to-next-to-leading order, which results in significant improvement in the accuracy of the parton distributions in the proton. Simultaneously, the value of the strong coupling constant at the Z boson mass is extracted as α$_{S}$(m$_{Z}$) = 0.1170±0.0019. For the first time, these data are used in a standard model effective field theory analysis at next-to-leading order, where parton distributions and the QCD parameters are extracted simultaneously with imposed constraints on the Wilson coefficient c$_{1}$ of 4-quark contact interactions.[graphic not available: see fulltext