| 1. |
- Ala-Laurinaho, J., et al.
(författare)
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TUMESA - MEMS tuneable metamaterials for smart wireless applications
- 2012
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Ingår i: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012. - : IEEE. - 9782874870286 ; , s. 95-98
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Konferensbidrag (refereegranskat)abstract
- This paper describes the main results of the EU FP7 project TUMESA - MEMS tuneable metamaterials for smart wireless applications. In this project, we studied several reconfigurable antenna approaches that combine the new technology of MEMS with the new concept of artificial electromagnetic materials and surfaces (metamaterials and metasurfaces) for realisation of millimetre wave phase shifters and beam-steering devices. MEMS technology allows to miniaturise electronic components, reduce their cost in batch production, and effectively compete with semiconductor and ferroelectric based technologies in terms of losses at millimetre wavelengths. Novel tuneable materials and components proposed in this project perform as smart beam steering devices. Fabricated with MEMS technology in batch and on a single chip, proposed tuneable devices allow substituting of larger and more complex sub-system of, e.g., a radar sensor. This substitution provides a dramatic cost reduction on a system level.
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| 2. |
- Vorobyov, A., et al.
(författare)
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Iris-based 2-bit waveguide phase shifters and transmit-array for automotive radar applications
- 2012
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Ingår i: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. - : IEEE. - 9781457709180 ; , s. 3711-3715
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Konferensbidrag (refereegranskat)abstract
- Three-pole iris-based bandpass filters are proposed as waveguide phase shifters for automotive applications at 77 GHz. Compared to standard configurations with symmetrical irises, asymmetrical designs have been preferred here in order to minimize technological constraints in the perspective of designing beam steering transmit-array antennas. Here the irises are printed on thin Silicon substrates integrated into a WR-12 metallic waveguide. A 210-element transmit-array antenna is also designed at 77GHz using, as building blocks, four different kinds of phase shifters providing a nearly 2-bit phase quantization in the radiation aperture. The phase shifter design are validated in X-band, and a very good agreement between simulations and measurements has been obtained both in amplitude and phase.
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| 3. |
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| 4. |
- Girnyk, Maksym, et al.
(författare)
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On the optimal relay design for multi-antenna cognitive two-way AF relay networks
- 2015
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Ingår i: Conference Record. - 9781479982974 ; , s. 1579-1583
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Konferensbidrag (refereegranskat)abstract
- Cognitive relaying is an efficient method for tackling the problem of spectrum scarcity by serving new (secondary) users, while keeping the existing (primary) users satisfied with their service. Moreover, additional gains can be attained from employment of the two-way relaying with multiple-antenna relays within the secondary network. In this paper, we consider an underlay two-way cognitive network and propose an efficient algorithm for computing a (nearly) optimal relay precoder matrix subject to the interference constraint towards the primary network. The efficiency of the proposed solution is highlighted by means of numerical simulations.
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| 5. |
- Seiler, N., et al.
(författare)
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Cfd Simulation Benchmark on Thermal-Hydraulic Behaviour of Light Metal Layer
- 2023
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Ingår i: Proceedings of the 30th International Conference on Nuclear Engineering "Nuclear, Thermal, and Renewables: United to Provide Carbon Neutral Power", ICONE 2023. - : American Society of Mechanical Engineers (ASME).
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Konferensbidrag (refereegranskat)abstract
- In the framework of the IAEA Coordinated Research Project on In-Vessel Melt Retention, a benchmark of CFD simulations, devoted to thermal-hydraulic behavior of the light metal layer involves several research organizations: KTH of Sweden, SSTC NRS of Ukraine, ÚJV Řež of Czech Republic and CEA of France. This work aims at better simulating the focusing effect phenomenon leading to a heat flux peak along the height of the light metal layer, which is formed above the oxide layer in a stratified corium pool configuration during a PWR severe accident. This is a known safety issue compromising the reactor vessel integrity. The first benchmark step provides a solid foundation to the CFD schemes (physical models, meshes) by comparing the results of CFD simulations with thermal-hydraulic experimental data obtained using water as simulating fluid in a representative and quite laminar configuration. Then a similar but highly turbulent case, of higher height, is considered for more complex validation of the numerical simulation approach. Results with different turbulent models are compared against experimental data. On the strength of this encouraging work, a simulation of the same height configuration but considering steel fluid under severe accident conditions is foreseen at the final stage of this benchmark.
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