Wyniki wyszukiwania - BazTech

1

VTS simulator SAR module for rescue operation planning

Kotkowska Diana

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2020

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nr 62 (134)

151--160

EN

This article presents the capabilities of a SAR module during rescue operation planning and control. The Navi-Harbour SAR module was used during an exercise, which enabled an operator to plan and monitor the rescue operations of selected water areas. To present the basic capabilities of this module, we prepared a case for the SAR action for a man overboard in the Baltic Sea using actual available SAR resources in this area. For the basic assumptions of the scenario, a research plan was developed that included an assessment of the most probable position of a threatened unit, taking into account the weather conditions in this area.

2

On streamwise structures in boundary layer under adverse pressure gradient on inclined plate

Uruba V., Prochazka P., Skala V.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2018

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Vol. 22, No 3

255--267

EN

The presented study is focused on experimental investigation of a boundary layer on a flat plate in an adverse pressure gradient. The flat plate is placed in a regular flow, the pressure gradient is generated by the plate inclination. The preceding studies deal with the structure of the wake behind the plate, the presented study concentrates on the flow structureclose to the suction surface of the plate. The dynamical behavior of the flow structures is studied in details with respect to the topology in the streamwise direction. In spite of the fact that thetime-mean flow field is close to 2D, more or less constant along the span, the instantaneous structures topology is fully 3D. Rather oblique structures are detected instead of those oriented in the streamwise direction. The patterns are travelling in the streamwise direction along the plate.

3

Model order reduction of Mikota’s vibration chain including damping effects by means of proper orthogonal decomposition

Weber W. E., Zastrau B. W.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 2

511--521

EN

In engineering disciplines, both in scientific and practical applications, systems with a tremendous number of degrees of freedom occur. Hence, there is a need for reducing the computational effort in investigating these systems. If the system behaviour has to be calculated for many time instances and/or load scenarios, the need for efficient calculations further increases. Model order reduction is a common procedure in order to cope with such large systems. The aim of model order reduction is to reduce the (computational) effort in solving the given task while still keeping main features of the respective system. One approach of model order reduction uses the proper orthogonal decomposition. This approach is applied to Mikota’s vibration chain, a linear vibration chain with remarkable properties, where two cases of an undamped and a damped structure are investigated.

4

Particle Image Velocimetry and Proper Orthogonal Decomposition Applied to Aerodynamic Sound Source Region Visualization in Organ Flue Pipe

Mickiewicz W.

Archives of Acoustics

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2015

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Vol. 40, No. 4

475--484

EN

The paper presents experimental results of the visualization of the nonlinear aeroacoustic sound generation phenomena occurring in organ flue pipe. The phase-locked particle image velocimetry technique is applied to visualize the mixed velocity field in the transparent organ flue pipe model made from Plexiglas. Presented measurements were done using synchronization to the tone generated by the pipe itself supplied by controlled air flow with seeding particles. The time series of raw velocity field distribution images show nonlinear sound generation mechanisms: the large amplitude of deflection of the mean flue jet and vortex shedding in the region of pipe mouth. Proper Orthogonal Decomposition (POD) was then applied to the experimental data to separately visualize the mean mass flow, pulsating jet mass flow with vortices and also sound waves near the generation region as well as inside and outside of the pipe. The resulting POD spatial and temporal modes were used to approximate the acoustic velocity field behaviour at the pipe fundamental frequency. The temporal modes shapes are in a good agreement with the microphone pressure signal shape registered from a distance. Obtained decomposed spatial modes give interesting insight into sound generating region of the organ pipe and the transition area towards the pure acoustic field inside the resonance pipe. They can give qualitative and quantitative data to verify existing sound generation models used in Computational Fluid Dynamics (CFD) and Computational Aero-Acoustics (CAA).

5

Modal analysis of viscous flow and reduced order models

Nowak M., Stankiewicz W., Morzyński M.

Vibrations in Physical Systems

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2014

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Vol. 26

223--228

EN

Phenomena occurring in the flows are very complex. Their interpretation, as well as an effective impact on them in the flow control is often only possible with the use of modal analysis and low-dimensional models. In this paper, the selected modal decomposition techniques, namely Proper Orthogonal Decomposition (POD), Dynamic Mode Decomposition (DMD) and global stability analysis, are briefly introduced. The design of Reduced Order models basing on Galerkin projection is presented on the example of the flow past a bluff body. Finally, the issues of widening of the application of the models are addressed.

6

A 3D CFD model of a natural draft wet-cooling tower

Klimanek A., Białecki R.

Archives of Thermodynamics

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2009

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Vol. 30, no. 4

119-132

EN

A 3D CFD model of a natural draft wet-cooling tower is presented in this paper. The model encompasses both the interior of the tower as well as the surrounding air. The developed CFD model is supplied with a low dimensional representation of the heat and mass exchanger, whose purpose is to determine the heat and mass rejected from the cooled water to the air. The representation is based on an original technique called the proper orthogonal decomposition. Due to the large scale differences, application of a low-dimensional heat and mass transfer model allowed reducing the computational time and accurately predict the heat and mass rejection effects. The Euler-Euler multiphase model was used to calculate the flow, heat and mass transfer in the rain zone. The model can be used in both, design computations as well as performance tests of natural draft wet-cooling towers. The effects of wind on the cooling tower can be taken into account. The CFD model was developed using the commercial code Fluent.

7

Rekonstrukcja geometrii obiektów przestrzennych przy zredukowanej ilości danych pomiarowych

Rychlik M.

Eksploatacja i Niezawodność

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2004

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nr 2

45-49

PL

Budowa trójwymiarowych modeli używanych w systemach CAx, wymaga precyzyjnych danych geometrycznych. W zależności od aplikacji, konieczne jest pozyskanie (oprócz danych geometrycznych) dodatkowych danych takich jak: gęstość, tekstura powierzchni, itp. Autor prezentuje metody rekonstrukcji trójwymiarowych modeli w programach CAD i przedstawia koncepcją praktycznego zastosowania POD (Proper Orthogonal Decomposition). Trójwymiarowa rekonstrukcja POD bazuje na modach statystycznych opisujących obiekt 3D.

EN

The construction of three-dimensional models used in CAx systems, to require precision geometrical data of the real object is presented. Depending on application, it is necessary to obtain (besides geometrical dimensions) additional data such as: volume density, texture of the surface, etc. Author shows method of reconstruction 3D models in CAD software and presents conception of practicable Proper Orthogonal Decomposition (POD). The POD 3D reconstruction bases on the statistical modes which describe the 3D object.

8

Papiernictwo wobec wyzwań XXI w. - szanse i zagrożenia. Papiery do nowych systemów drukowych

Wandelt P.

Przegląd Papierniczy

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2000

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R. 56, nr 4

203--208