| 1. |
- Borodulin, V. I., et al.
(author)
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Excitation of 3D TS-waves in a swept-wing boundary layer by surface vibrations and freestream vortices
- 2018
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In: AIP Conference Proceedings. - : American Institute of Physics Inc.. - 0094-243X. - 9780735417472
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Conference paper (peer-reviewed)abstract
- There are several kinds of velocity disturbances, which may affect the transition to turbulence in a swept wing boundary layer. Tollmien-Schlichting (TS) waves are among most important of them. The properties of TS waves and their potential competition with cross-flow waves on a swept wing are poorly studied in theoretical works and were not studied experimentally at all. This paper presents the method of excitation of fully controlled 3D TS waves via interaction of free-stream vortices and surface vibrations. The experimental approach developed here will be used for investigation of the corresponding receptivity problem.
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| 2. |
- Borodulin, V. I., et al.
(author)
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Quantitative study of localized mechanisms of excitation of cross-flow instability modes in a swept-wing boundary layer
- 2018
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In: CONFERENCE OF YOUNG SCIENTISTS IN MECHANICS. - : IOP PUBLISHING LTD.
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Conference paper (peer-reviewed)abstract
- An experimental study of two efficient receptivity mechanisms of excitation of cross-flow (CF) instability modes is carried out in a boundary layer of a real airfoil section of a swept wing due to: (i) action of localized surface vibrations, and (ii) scattering of 2D freestream vortices on them. It is found that the two mechanisms lead to rather efficient excitation of CF-modes both at surface vibration frequency and at combination 'vortexvibration' frequencies. First estimations of the corresponding localized receptivity coefficients are obtained. Direct comparison of the experimental amplification curves of the excited CF-modes with those calculated based on the linear stability theory (LST) has shown that the experimental data obtained at vibration frequency are in excellent agreement with the LST. At the same time, growth rates of the CF-modes excited at combination frequencies are found to be completely inconsistent with the LST. A possible explanation of this phenomenon via action of a new efficient distributed receptivity mechanism is suggested. This mechanism is associated with scattering of freestream vortices on rather high-amplitude CF-modes excited by surface vibrations.
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| 3. |
- Borodulin, V. I., et al.
(author)
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Receptivity coefficients of vortex-vibrational type at excitation of 3D Tollmien-Schlichting waves in a boundary layer on a swept wing
- 2019
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In: HIGH-ENERGY PROCESSES IN CONDENSED MATTER (HEPCM 2019): Proceedings of the XXVI Conference on High-Energy Processes in Condensed Matter, dedicated to the 150th anniversary of the birth of S.A. Chaplygin. - : American Institute of Physics (AIP). - 9780735418653
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Conference paper (peer-reviewed)abstract
- The paper is devoted to the first results of an experimental quantitative study of the receptivity mechanism of a swept-wing laminar boundary layer related to scattering of 2D freestream vortices (with frequency fv) at 3D local surface vibrations (with frequency fs) resulting in an excitation of Tollmien-Schlichting (TS) waves (having combination frequencies f+ = fs+fv and f- = fs - fv). The experiments were carried out in a low-turbulence level wind tunnel on a high-precision experimental model of long-laminar-run swept airfoil (sweep angle of 35°) at a freestream speed of about 10 m/s. Controlled localized 3D surface vibrations and 2D freestream vortices were generated by special disturbance sources. Quantitative characteristics of the studied receptivity mechanism (receptivity coefficients) were estimated.
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| 4. |
- Kachanov, Y. S., et al.
(author)
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Generation of unsteady CF-instability modes by vibrational and vibration-vortex localized receptivity mechanisms
- 2018
-
In: AIP Conference Proceedings. - : American Institute of Physics Inc.. - 0094-243X. - 9780735417472
-
Conference paper (peer-reviewed)abstract
- The paper is based on results obtained within an international project 'RECEPT' of the European Framework Program FP7. The experiments were carried out in a three-dimensional boundary layer developing on an experimental model of a long-laminar-run swept airfoil (sweep angle of 35°). The model was mounted in a test section of the low-turbulence wind-tunnel MTL (KTH, Stockholm) at an angle of attack of -5°and equipped with sidewalls provided satisfaction of infinite-span conditions. The cross-flow (CF) instability modes were predominant in this case, while the Tollmien-Schlichting (TS) waves were suppressed by a favorable pressure gradient. The main measurements were carried out by means of hot-wire anemometry at conditions of excitation of fully controlled, unsteady surface and flow perturbations. These perturbations were excited by special sources: (1) a row of oscillating membranes and (2) a vibrating cwire, at frequencies of f s and f v , respectively. A very good, quantitative agreement between the measured and calculated (by linear stability theory based on PSE approach) amplification curves was found at surface frequency f s . However, the evolution of the CF-modes excited at difference combination frequency f sv- = f s - f v turned out to be very much different from the theoretical one. Thorough analysis of the obtained results has shown that the only explanation of these discrepancies can be associated with presence of a distributed receptivity mechanism due to scattering of freestream vortices on the CF-instability waves excited by surface vibrations. Another unusual and unexpected phenomenon found in the present experiments is associated with anomalous amplification of difference combination modes with the zero spanwise wavenumbers β′. This phenomenon was observed in the flow, which is stable with respect to both CF- and TS-waves having β′ = 0 for all frequencies. There is no explanation of this finding at present.
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| 5. |
- Borodulin, V. I., et al.
(author)
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Characteristics of 3D instability of a 35-degree swept wing to CF and TS modes. Experiment and theory
- 2016
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In: AIP Conference Proceedings. - : American Institute of Physics (AIP). - 0094-243X. - 9780735414280
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Conference paper (peer-reviewed)abstract
- An extensive experimental investigation of linear evolution of Cross-Flow (CF) and Tollmien-Schlichting (TS) modes of 3D boundary layer oscillations on a swept wing has been carried out. TS-instability characteristics have been studied experimentally for the first time. The characteristics of development of the two kinds of instability modes are compared with calculations and display a very good agreement. The whole dataset may be used for promotion of theoretical methods of investigation of laminar-turbulent transition in swept wing boundary layers.
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| 6. |
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| 7. |
- Hein Bengtson, Stefan, et al.
(author)
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A Shared Pose Regression Network for Pose Estimation of Objects from RGB Images
- 2022
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In: IEEE/RSJ International Conference on Signal Image Technology & Internet Based Systems (SITIS). - 9781665464956 - 9781665464963
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Conference paper (peer-reviewed)abstract
- In this paper we propose a shared regression network to jointly estimate the pose of multiple objects, replacing multiple object-specific solutions. We demonstrate that this shared network can outperform other similar approaches that rely on multiple object-specific models by evaluating it on the TLESS dataset using the VSD (Visible Surface Discrepancy). Our approach offers a less complex solution, with fewer parameters, lower memory consumption and less training required. Furthermore, it inherently handles symmetric objects by using a depth-based loss during training and can predict in real-time. Finally, we show how our proposed pipeline can be used for fine-tuning a feature extractor jointly on all objects while training the shared pose regression network. This fine-tuning process improves the pose estimation performance.
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| 8. |
- Hein, Maria, et al.
(author)
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Understanding the embedded carbon challenges of building service systems
- 2021
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In: Proceedings of the Design Society. - : Cambridge University Press (CUP). - 2732-527X. ; , s. 3279-3288
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Conference paper (peer-reviewed)abstract
- Energy consumed in buildings is a main contributor to CO2 emissions, there is therefore a need to improve the energy performance of buildings, particularly commercial buildings whereby building service systems are often substantially over-designed due to the application of excess margins during the design process. The cooling system of an NHS Hospital was studied and modelled in order to identify if the system was overdesigned, and to quantify the oversizing impact on the system operational and embodied carbon footprints. Looking at the operational energy use and environmental performance of the current system as well as an alternative optimised system through appropriate modelling and calculation, the case study results indicate significant environmental impacts are caused by the oversizing of cooling system. The study also established that it is currently more difficult to obtain an estimate of the embodied carbon footprint of building service systems. It is therefore the responsibility of the machine builders to provide information and data relating to the embodied carbon of their products, which in the longer term, this is likely to become a standard industry requirement.
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