| 1. |
- Andersson, Malte, 1941, et al.
(författare)
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”Minskande befolkning är inte problemet”
- 2020
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Ingår i: Dagens Nyheter. ; :1 augusti, DN-debatt
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Nätverket Population Matters Sweden: En uppmärksammad studie i The Lancet pekar mot en lägre befolkningsökning i världen än tidigare prognoser. Men en miljard människor till är fortfarande långt över vad jorden klarar. Befolkningstrenden måste snarare vända neråt, och det kräver åtgärder för att stärka kvinnors rättigheter världen över.
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| 2. |
- Ohlsson, Lars, et al.
(författare)
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Admittance Matching of 60 GHz Rectangular Dielectric Resonator Antennas for Integrated Impulse Radio
- 2010
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Ingår i: [Host publication title missing]. ; , s. 253-256
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Konferensbidrag (refereegranskat)abstract
- Methods to achieve admittance matching of rectangular dielectric resonator antennas intended for 60~GHz impulse radio are reported. The motivation is to find a suitable antenna that may be integrated in the V-band gated tunnel diode wavelet generator, replacing its tank circuit and forming a low complexity transmitter. Probed one- and two-port scattering parameter measurements have been performed to characterise the fabricated antennas. Changing the feed structure from a tapered dipole to an offset fed and tapered slot, a change from capacitive to inductive characteristics is observed, and the matching to the gated tunnel diode is improved. Deembedded admittance resonance frequencies of fabricated antennas were found at 53.6 and 52.2~GHz for dipole and slot fed antennas, respectively. Characterising the transmission link between dipole fed antennas, a maximum antenna gain of 10.5~dBi and a 3~dB power bandwidth of 1.5~GHz were found at 53.3~GHz.
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| 3. |
- Ohlsson, Lars, et al.
(författare)
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A transmission line model for co-designed slot-coupled dielectric resonator antennas
- 2017
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Ingår i: European Microwave Week 2016: "Microwaves Everywhere", EuMW 2016 - Conference Proceedings; 46th European Microwave Conference, EuMC 2016. - 9782874870439 ; , s. 333-336
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Konferensbidrag (refereegranskat)abstract
- Co-design of monolithically-integrated millimetre-wave front-ends and antennas is alleviated by accurate device models. In this paper, a novel transmission line model for slotcoupled dielectric resonator antennas is proposed and verified. It describes distributed interaction between the coupling-structure and the radiating dielectric body of the antenna. This model thereby provides a simplistic and intuitive description of the main radiation mechanism. It fits with excellently to numerical full-wave simulation results, both in terms of input characteristics and radiation efficiency. Furthermore, the radiated signal fidelity predicted by the model is found in line with experimental results from a co-designed millimetre-wave wavelet transmitter. This antenna model promise further development into a generic scalable model that will reduce the need for iterative simulations.
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| 4. |
- Ohlsson, Lars, et al.
(författare)
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Codesign of Compact III-V Millimeter-Wave Wavelet Transmitters with On-Chip Antennas
- 2018
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 66:1, s. 273-279
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Tidskriftsartikel (refereegranskat)abstract
- Monolithically integrated millimeter-wave wavelet transmitters are presented and analyzed in this paper. Two designs that include compact dielectric resonator antennas with either inductive or self-resonant input characteristics are compared. The efficient transmitter front-end core consists of a resonant tunneling diode oscillator that is quenchable by a transistor switch. A physical diode model is used to formulate small-signal matching criteria and study codesign conditions. Fabricated transmitters provide up to 11-dBm equivalent isotropically radiated power in down to 80-ps wideband wavelets at V-band carrier frequencies. Analyses of the radiated waveform envelope and time-frequency characteristics give insight in the circuit operation.
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| 5. |
- Ohlsson, Lars, et al.
(författare)
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Monolithically-Integrated Millimetre-Wave Wavelet Transmitter With On-Chip Antenna
- 2014
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Ingår i: IEEE Microwave and Wireless Components Letters. - 1531-1309. ; 24:9, s. 625-627
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Tidskriftsartikel (refereegranskat)abstract
- An integrated millimeter-wave wavelet transmitter has been fabricated and characterized. It consists of a generator core on a co-designed compact monolithically-integrated antenna. The peak output equivalent isotropic radiated power has been measured to 11 dBm, in 80, 160, and 320 ps wavelets centred at 63.5 GHz. This corresponds to a power of 5 dBm radiated from the 6 dBi antenna. At a dc-supply of 1.45 V, the on-state power dissipation was estimated to 37 mW. The radiated wavelet-power over dc-dissipation conversion-efficiency is 9%.
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| 6. |
- Ohlsson, Lars, et al.
(författare)
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Slot-Coupled Millimeter-Wave Dielectric Resonator Antenna for High-Efficiency Monolithic Integration
- 2013
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 61:4, s. 1599-1607
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Tidskriftsartikel (refereegranskat)abstract
- A readily mass-producible, flip-chip assembled, and slot-coupled III-V compound semiconductor dielectric resonator antenna operating in the millimeter-wave spectrum has been fabricated and characterized. The antenna has a 6.1% relative bandwidth, deduced from its 10 dB return loss over 58.8-62.5 GHz, located around the resonance at 60.5 GHz. Gating in the delay-domain alleviated the analysis of the complex response from the measured structure. The radiation efficiency is better than -0.1 dB in simulations fed from the on-chip coupling-structure, but reduced by 3.7 dB insertion loss through the measurement assembly feed. Antenna gain measurements show distortion in relation to the simulated pattern, which has a maximum gain of 6 dBi, mainly caused by interference from the electrically large connector used in the assembly. Mode degeneration in the utilized quadratic-footprint resonator was not seen to influence the performance of the antenna. The antenna is intended for on-chip integration and the fabrication technology allows scaling of the operation frequency over the complete millimeter-wave spectrum.
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| 7. |
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| 8. |
- Azizoğlu, Yağız, 1986-, et al.
(författare)
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Finite Element Analysis of cold pilgering using elastic roll dies
- 2017
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Ingår i: Procedia Engineering. - : Elsevier. - 1877-7058. ; 207, s. 2370-2375
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Tidskriftsartikel (refereegranskat)abstract
- A finite element model of cold pilgering with elastic roll dies have been developed and used to investigate the influence of roll die deformation on the material flow, contact region, roll separating force and tube dimensions. Full scale experiments were performed to validate the contact surface and tube dimensions. The results show that the influence of roll die flattening is not significant on the contact length. However, elastic deformation of roll die has strong influence on both the wall thickness reduction and roll separating force. Thus it is recommended to consider elasticity of roll dies when forces and tube dimensions are estimated.
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| 9. |
- Azizoğlu, Yağız, et al.
(författare)
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Finite element modeling of tube deformation during cold pilgering
- 2016
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Ingår i: MATEC Web of Conferences. - : EDP Sciences. ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- A three-dimensional finite element model of cold pilgering of stainless steel tubes is developed in this paper. The objective is to use the model to increase the understanding of forces and deformations in the process. The focus is on the influence of vertical displacements of the roll stand and axial displacements of the mandrel and tube. Therefore, the rigid tools and the tube are supported with elastic springs. Additionally, the influences of friction coefficients in the tube/mandrel and tube/roll interfaces are examined. A sensitivity study is performed to investigate the influences of these parameters on the strain path and the roll separation force. The results show the importance of accounting for the displacements of the tube and rigid tools on the roll separation force and the accumulative plastic strain.
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| 10. |
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