| 3. |
- Kashyap, Salil, et al.
(author)
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Performance Analysis of (TDD) Massive MIMO With Kalman Channel Prediction
- 2017
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In: 2017 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP). - : IEEE. - 9781509041176 ; , s. 3554-3558
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Conference paper (peer-reviewed)abstract
- In massive MIMO systems, which rely on uplink pilots to estimate the channel, the time interval between pilot transmissions constrains the length of the downlink. Since switching between up-and downlink takes time, longer downlink blocks increase the effective spectral efficiency. We investigate the use of low-complexity channel models and Kalman filters for channel prediction, to allow for longer intervals between the pilots. Specifically, we quantify how often uplink pilots have to be sent when the downlink rate is allowed to degrade by a certain percentage. To this end, we consider a time-correlated channel aging model, whose spectrum is rectangular, and use autoregressive moving average (ARMA) processes to approximate the time-variations of such channels. We show that ARMA-based predictors can increase the interval between pilots and the spectral efficiency in channels with high Doppler spreads. We also show that Kalman prediction is robust to mismatches in the channel statistics.
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| 4. |
- Kondratyuk, Sergij, et al.
(author)
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Three new genera of the Teloschistaceae proved by three gene phylogeny
- 2020
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In: Acta Botanica Hungarica. - : Akademiai Kiado Zrt.. - 1588-2578 .- 0236-6495. ; 62:1-2, s. 109-136
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Journal article (peer-reviewed)abstract
- Three new for science genera, i.e.: Erichansenia S. Y. Kondr., Kärnefelt et A. Thell for the ‘Caloplaca’ epithallina group of the subfamily Xanthorioideae, as well as Lendemeriella S. Y. Kondr. for the Caloplaca reptans group, and Pisutiella S. Y. Kondr., L. Lőkös et E. Farkas for the Caloplaca conversa group of the subfamily Caloplacoideae of the Teloschistaceae, are described on the basis of results of the three gene phylogeny of the Teloschistaceae based on nrITS, nrLSU and mtSSU sequences.Twenty-seven new combinations, i.e.: Erichansenia epithallina (for Caloplaca epithallina Lynge), Erichansenia cryodesertorum (for Shackletonia cryodesertorum Garrido-Ben., Søchting et Pérez-Ort.), Erichansenia sauronii (for Caloplaca sauronii Søchting et Øvstedal), Fauriea mandshuriaensis (for Caloplaca mandshuriaensis S. Y. Kondr., L. Lőkös et J.-S. Hur), Fauriea trassii (for Caloplaca trassii Galanina et S. Y. Kondr.), Lendemeriella borealis (for Lecanora pyracea f. borealis Vain.), Lendemeriella dakotensis (for Caloplaca dakotensis Wetmore), Lendemeriella exsecuta (for Lecanora exsecuta Nyl.), Lendemeriella lucifuga (for Caloplaca lucifuga G. Thor), Lendemeriella nivalis (for Zeora nivalis Körb.), Lendemeriella reptans (for Caloplaca reptans Lendemeret B. P. Hodk.), Lendemeriella sorocarpa (for Placodium sorocarpum Vain.), Lendemeriella tornoensis (for Caloplaca tornoensis H. Magn.), Pisutiella congrediens (for Lecanora congrediens Nyl.), Pisutiella conversa (for Callopisma conversum Kremp.), Pisutiella furax (for Caloplaca furax Egea et Llimona), Pisutiella grimmiae (for Lecanora grimmiae Nyl.), Pisutiella ivanpisutii (for Caloplaca ivanpisutii S. Y. Kondr., L. Lőkös et Hur), Pisutiella phaeothamnos (for Caloplaca phaeothamnos K. Kalb et J. Poelt), Pyrenodesmia aetnensis (for Caloplaca aetnensis B. de Lesd.), Pyrenodesmia albolutescens (for Lecanora albolutescens Nyl.), Pyrenodesmia aractina (for Parmelia aractina Fr.), Pyrenodesmia atroflava (for Lecidea atroflava Turner), Pyrenodesmia bicolor (for Caloplaca bicolor H. Magn.), Pyrenodesmia molariformis (for Caloplaca molariformis Frolov, Vondrák, Nadyeina et Khodos.), Pyrenodesmia neotaurica (for Caloplaca neotaurica Vondrák, Khodos., Arup et Søchting), Pyrenodesmia peliophylla (for Placodium peliophyllum Tuck.) are proposed based on results from a combined phylogenetic analysis using nrITS, nrLSU and mtSSU gene sequences.
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| 6. |
- Omulo, Godfrey, et al.
(author)
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Are emerging farmers the missing link for mechanised Conservation agriculture? Viewpoints from Zambia
- 2022
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In: Development in Practice. - : Informa UK Limited. - 0961-4524 .- 1364-9213. ; 32:3, s. 411-417
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Journal article (peer-reviewed)abstract
- Conservation agriculture’s (CA) potential to improve resilience to climate change, environmental degradation, and food insecurity across Africa is hampered by critical challenges, especially high labour requirements without mechanisation. Yet, whether medium-scale farmers owning 5–100 hectares of farmland and tractors can be the antidote for CA upscaling remains unclear. Based on insights from Zambia, the authors argue that medium-scale farmers can contribute to CA upscaling since they cultivate large farms and rent tractors to smallholder farmers. Harnessing the synergies between CA, mechanisation, and medium-scale farmers requires research on how they perceive CA, the enabling environment for mechanised CA, and appropriate policies.
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