Wyniki wyszukiwania - BazTech

1

Spring at CERN: a new stage of experiments, new results

Nowina-Konopka Małgorzata

Postępy Techniki Jądrowej

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2022

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z. 2

2--6

PL

CERN – Europejskie Centrum Badań Jądrowych – największe na świecie laboratorium fizyki cząstek obsługuje sieć siedmiu akceleratorów. Największy z nich LHC (Wielki Zderzacz Hadronów) rozpoczął skuteczne działanie w listopadzie 2009 r. Po intensywnym zbieraniu danych, związanym z odkryciem bozonu Higgsa, LHC przechodził pierwszy dwuletni (2013-2015) okres przestoju, w celu osiągnięcia pełnej świetlności przy energii 14 TeV między innymi przez wzmocnienie urządzeń elektrycznych łączących magnesy. Ponownie został wyłączony na ponad trzy lata od grudnia 2018 r. do kwietnia 2022, aby wprowadzić w obiekcie kolejne ulepszenia i aktualizacje. W czasie przerw opracowywano dane zebrane z eksperymentów ATLAS, CMS, LHCb i ALICE oraz prowadzono zderzenia na innych niż LHC akceleratorach i urządzeniach jak np. AMS czy ASACUSA. W artykule przedstawiono najnowsze wyniki tych obliczeń i eksperymentów opublikowane w czasopiśmie Nature.

EN

CERN - The European Nuclear Research Center – the world's largest particle physics laboratory is operated by a network of seven accelerators. The largest of these, the LHC (Large Hadron Collider), started operating effectively in November 2009. After extensive data collection related to the discovery of the Higgs boson, the LHC went through the first two-year (2013-2015) downtime to achieve full luminosity at 14 TeV inter alia by strengthening the electrical devices that connect the magnets. It has been shut down again for over three years from December 2018 through April 2022 to bring further improvements and updates to the facility. During the breaks, data collected from the ATLAS, CMS, LHCb and ALICE experiments was processed, and collisions were carried out on accelerators and devices other than LHC, such as for exemple AMS or ASACUSA. This paper presents the latest results from these calculations and experiments published in the journal Nature.

2

Efect of apron roughness on fow characteristics and scour depth under submerged wall jets

Aamir Mohammad, Ahmad Zulfequar

Acta Geophysica

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2022

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Vol. 70, no 5

2205--2221

EN

Scour downstream of smooth and rough rigid aprons under wall jets has been studied experimentally. Effect of apron roughness on scour has been investigated, and quantification of reduction in the scour depth due to rough apron has been performed. Characteristics of velocity and turbulence over smooth and rough aprons as well as within the scour hole have been analyzed to study the behavior of the jet and its interaction with the rough apron. Results show that there is a significant reduction in the equilibrium scour depth due to roughness. A maximum of 82.8% and a minimum of 31.1% reduction in the equilibrium scour depth was observed due to inducing roughness over the rigid apron. Velocity characteristics establish the cause of reduction in the equilibrium scour depth, which is due to reduction in the erosive capacity of the jet as it moves over the rough apron. The potential core of the jet gets consumed at a much lesser length due to roughness over the apron than over a smooth apron, as the boundary layer develops at a smaller distance. Further, it was observed that it takes a smaller length for the flow to get fully developed under the rough apron as compared with the smooth apron. Based on the results of the present analysis, recommendation can be made for use of roughness over the apron to restrict scour due to wall jets.

3

Modelling of transcritical and supercritical nitrogen jets

Antunes E., Silva A., Barata J.

Combustion Engines

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2017

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R. 56, nr 2

125--132

EN

The present paper addresses the modelling of fuel injection at conditions of high pressure and temperature which occur in a variety of internal combustion engines such as liquid fuel rocket engines, gas turbines, and modern diesel engines. For this investigation a cryogenic nitrogen jet ranging from transcritical to supercritical conditions injected into a chamber at supercritical conditions was modelled. Previously a variable density approach, originally conceived for gaseous turbulent isothermal jets, imploying the Favre averaged Navier-Stokes equations together with a “k-ε” turbulence model, and using Amagats law for the determination of density was applied. This approach allows a good agreement with experiments mainly at supercritical injection conditions. However, some departure from experimental data was found at transcritical injection conditions. The present approach adds real fluid thermodynamics to the previous approach, and the effects of heat transfer. The results still show some disagreement at supercritical conditions mainly in the determination of the potential core length but significantly improve the prediction of the jet spreading angle at transcritical injection conditions.

4

The evolution of correlation functions from low to high pT in PHENIX: from HBT to jets

Mitchell J.

Nukleonika

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2006

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Vol. 51,suppl.3

79-81

EN

The PHENIX experiment at the Relativistic Heavy Ion Collider has performed a survey of momentum correlations ranging from 200 MeV/c to 7 GeV/c in sNN = 200 GeV p+p, d+Au, Au+Au, and sNN = 62 GeV Au+Au collisions. The correlations are measured separately for like-sign and unlike-sign pairs. Comparisons of the properties of the near-side peak amplitude and width as a function of centrality and transverse momentum for each collision species are presented and discussed.

5

Effect of hard processes on momentum correlations

Paić G., Skowroński P., Tomašik B.

Nukleonika

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2004

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Vol. 49,suppl.2

89-94

EN

The effect of hard processes to be encountered in HBT studies at the Large Hadron Collider (LHC) have been studied. A simple simulation has allowed us to generate momentum correlations involving jet particles as well as particles originating from the kinetic freeze-out and to compare them to a simple theoretical model which has been developed. The first results on the effect of hard processes on the correlation function for the case of jet quenching are presented.

6

The natural affinors on the r-jet prolongations of a vector bundle

Mikulski W. M.

Demonstratio Mathematica

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2004

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Vol. 37, nr 3

709--717

7

Interaction of jet with opposing supersonic stream in the presence of a circular flat plate

Svirschevsky S., Semenchikov N., Tarkov E.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

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2001

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nr 12

85-92

EN

Experimental results of investigations of an interaction of a single jet with an opposing supersonic flow in the presence of a circular flat plate are presented. The tests have been performed at the free stream Mach number Moo = 1.99 and the following jet parameters: the nozzle exit Mach number Mj = 4.3, relative stagnation pressure of a jet (the interaction parameter) N = 1-1389.9. The jet expansion ratio in tests varied from n < 1 to n = 34.8. The wave structures and stagnation pressure fields near jet were investigated. The reference zones and flow regimes of interaction of a jet with opposing airflow were detected. It was established, that the value of a total pressure coefficient in these zones depended on the interaction parameter N at fixed values of the Mach numbers Moo, Mj and nozzle source geometrical parameter D = DM / dj. It was shown that the drag of a circular flat plate with a jet could be increased in comparison with the drag of an isolated plate.