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Multi-scale waves in sound-proof global simulations with EULAG

Prusa J.M., Gutowski W.J.

Acta Geophysica

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2011

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Vol. 59, no. 6

1135-1157

EN

EULAG is a computational model for simulating flows across a wide range of scales and physical scenarios. A standard option employs an anelastic approximation to capture nonhydrostatic effects and simultaneously filter sound waves from the solution. In this study, we examine a localized gravity wave packet generated by instabilities in Held-Suarez climates. Although still simplified versus the Earth's atmosphere, a rich set of planetary wave instabilities and ensuing radiated gravity waves can arise. Wave packets are observed that have lifetimes ≤ 2 days, are negligibly impacted by Coriolis force, and do not show the rotational effects of differential jet advection typical of inertia-gravity waves. Linear modal analysis shows that wavelength, period, and phase speed fit the dispersion equation to within a mean difference of ∼ 4 per cent, suggesting an excellent fit. However, the group velocities match poorly even though a propagation of uncertainty analysis indicates that they should be predicted as well as the phase velocities. Theoretical arguments suggest the discrepancy is due to nonlinearity - a strong southerly flow leads to a critical surface forming to the southwest of the wave packet that prevents the expected propagation.

2

Wykorzystanie submodelingu do modelowania zachowania się budowli poddanej wpływom eksploatacji

Tajduś K., Tajduś A.

Górnictwo i Geoinżynieria

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2007

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R. 31, z. 3/1

529-541

PL

Artykuł przedstawia analizę doboru odpowiednich warunków brzegowych dla modelowanego zjawiska wpływu eksploatacji podziemnej na budowlę. Autorzy skłonili się do próby rozwiązania tego problemu w sposób dwuczłonowy, wykorzystując model globalny i submodel. W technice zaproponowanej przez autorów warunki brzegowe zadawane na submodel stanowiły przemieszczenia pionowe i poziome wyliczone z modelu globalnego. Dodatkowo przeprowadzono analizę wpływu wielkości modelowanego podłoża, na stan naprężenia wewnątrz posadowionego na nim fundamentu.

EN

This paper describes the correct selections of the bonduary conditions, of the models presents the influence of the underground excavations on the bulding based on FEM. The authors incline to solve this problem by using the dobblepart methods, based on global model and sub-model. In this technic the boundary conditions of the sub-model are the value of vertical and horizontal displacements calculate previously in global model. Aditionally the authors made some calculations of the influence of the size of the model bedrock of the stress values in the fundations based on it.

3

Numeryczne modele prognoz pogody

Pietrek S.

Zeszyty Naukowe Warszawskiej Wyższej Szkoły Informatyki

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2006

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nr 1

93--103

PL

W referacie przestawiono wprowadzenie do problematyki opracowywania numerycznych modeli prognoz pogody. Omówione zostały zagadnienia tworzenia modeli globalnych, regionalnych i mezoskalowych wraz z procedurą tzw. „zagnieżdżania modeli”. Przedstawiono charakterystykę mezoskalowego modelu UMPL dla obszaru Polski wraz z zasadami konstrukcji siatki obliczeniowej modelu oraz wyborem odwzorowań kartograficznych dla map zawierających horyzontalne rozkłady parametrów meteorologicznych. Oryginalnym wynikiem przeprowadzonych badań jest uzyskiwanie pionowych przekrojów atmosfery wzdłuż dowolnej trasy. Otrzymywane produkty wykorzystywane są do osłony meteorologicznej kraju, a w szczególności do zabezpieczenia działań lotnictwa.

EN

The paper presents a concept of application of non-standard atmospheric parameters charts, determined on the basis of the UMPL (Unified Model for Poland Area) mesoscale model data, to synoptic analysis. Effective weather forecasts for aviation, including additional information about vertical profiles of meteorological elements, require objective forecast of the atmospheric state based on the results of numerical models and remotely sensed data. The procedure can be applied to points of geographical coordinates corresponding e.g. to a planned route of an aircraft.

4

Numerical simulation of tensile loaded lap riveted joint

Szymczyk E., Derewońko A., Kiczko A., Jachimowicz J.

Journal of KONES

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2006

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Vol. 13, No. 3

381-388

EN

The paper deals with the analysis of the global shell–beam model of a riveted lap joint consisting of six rivets. This is a stage of study of the local physical phenomena in riveted joint [3 – 12]. The contact with friction is defined between collaborating parts of the joint. The calculations are carried out in an elastic-plastic range. The influence of the specimen geometry, boundary conditions, rivet stiffness and the sheet material model on strain and stress fields in the riveted joint is studied. Numerical models are verified on the base of experimental tests. In particular plastic strain fields during tensile loading, stress fields during tensile loading, comparison of numerical results, plastic strain fields around the hole, stress fields in the whole specimen are presented in the paper. Results demonstrated that the specimen geometry has important influence on the stress and strain fields in the final stage of tensile loading. The advantage of the numerical simulation is limiting development costs and improving analysis by giving more complete information about stress and strain fields compared to the pure experimental way. The stress and strain fields can be presented in the neighbourhood of a contact interface, where it is impossible to detect and measure it experimentally.