ZWIĘKSZENIE WYDAJNOŚCI ENERGETYCZNEJ SPRZĘTU RADIOWEGO W OPARCIU O STOSOWANIE MODULACJI PRZEZ ORTOGONALNE HARMONICZNE

Most of the theoretical results, as well as methods using OFDM modulation, are obtained in order to increase the rate of information transmission with energy constraints and the bandwidth. For broadband radio access systems, this task is primarily due to the commercial purpose of these systems and the desire of the communications developers to provide high-speed wireless access to the Internet as much as possible at the same time. This article is devoted to the issue of increasing the energy efficiency of radio equipment using modulation orthogonal harmonic carriers under conditions of intentional interference and frequency-selective fading while ensuring a given level of reliability and speed of information transmission.Większość wyników teoretycznych, a także metod wykorzystujących modulację OFDM, uzyskuje się w celu zwiększenia szybkości transmisji informacji z ograniczeniami energetycznymi i przepustowością. W przypadku szerokopasmowych systemów dostępu radiowego zadanie to wynika przede wszystkim z komercyjnego celu tych systemów i chęci twórców komunikacji, aby zapewnić szybki bezprzewodowy dostęp do Internetu w jak największym stopniu w tym samym czasie. Artykuł poświęcony jest zwiększeniu wydajności energetycznej urządzeń radiowych z wykorzystaniem modulacji ortogonalnych nośników harmonicznych w warunkach zamierzonego zakłócania i selektywnego opadania częstotliwości, przy jednoczesnym zapewnieniu określonego poziomu niezawodności i prędkości transmisji informacji

2019 IEEE 9th International Conference Nanomaterials: Applications & Properties (NAP-2019)

This is a post-peer-review, pre-copyedit version of an article published in 2019 IEEE 9th International Conference Nanomaterials: Applications & Properties (NAP). The final authenticated version is available online at: https://doi.org/10.1109/NAP47236.2019.216967Ministry of Education and Science of Ukraine [project # 2106]This study reports the structural evolution of multi-component AlNiCoFeCrTi high-entropy alloy from elemental materials to nanocrystalline metastable solid solution during mechanical alloying (MA), and further, to equilibrium phases during subsequent thermal annealing. It was justified experimentally that shot-time mechanical milling of Al-Ni-Co-Fe-Cr-Ti powder mixture during 3 hours resulted in a single-phase nanocrystalline high-entropy alloy (HEA) with a structure of bcc solid solution. During thermal annealing of the bcc solid solution phase transformation take place, and grain growth of equilibrium phases occur. The phase composition of as-MA alloy transforms to fcc and bcc solid solutions with TiC precipitations’ when the MA powder was annealed at 1200 °C for 1 h. X-ray diffraction and electron microscopy data show that the nanocrystalline powder microstructure is retained in the alloy with no grain growth. The AlNiCoFeCrTi HEA exhibit 7.1 GPa and 9.2±0.3 GPa in Vickers hardness after mechanical alloying and after thermal annealing, respectively

Crowdsourcing Fungal Biodiversity : Revision of Inaturalist Observations in Northwestern Siberia

The paper presents the first analysis of crowdsourcing data of all observations of fungi (including lichens) and myxomycetes in Northwestern Siberia uploaded to iNaturalist.org to date (24.02.2022). The Introduction presents an analysis of fungal diversity crowdsourcing globally, in Russia, and in the region of interest. Materials and methods describe the protocol of uploading data to iNaturalist.org, the structure of the crowdsourcing community. initiative to revise the accumulated data. procedures of data analysis, and compilation of a dataset of revised crowdsourced data. The Results present the analysis of accumulated data by several parameters: temporal, geographical and taxonomical scope, observation and identification efforts, identifiability of various taxa, species novelty and Red Data Book categories and the protection status of registered observations. The Discussion provides data on usability of crowdsourcing data for biodiversity research and conservation of fungi, including pros and contras. The Electronic Supplements to the paper include an annotated checklist of observations of protected species with information on Red Data Book categories and the protection status, and an annotated checklist of regional records of new taxa. The paper is supplemented with a dataset of about 15 000 revised and annotated records available through Global Biodiversity Information Facility (GBIF). The tradition of crowdsourcing is rooted in mycological societies around the world, including Russia. In Northwestern Siberia, a regional mycological club was established in 2018, encouraging its members to contribute observations of fungi on iNaturalist.org. A total of about 15 000 observations of fungi and myxomycetes were uploaded so far, by about 200 observers, from three administrative regions (Yamalo-Nenetsky Autonomous Okrug, Khanty-Mansi Autonomous Okrug, and Tyumen Region). The geographical coverage of crowdsourcing observations remains low. However. the observation activity has increased in the last four years. The goal of this study consisted of a collaborative effort of professional mycologists invited to help with the identification of these observations and analysis of the accumulated data. As a result, all observations were reviewed by at least one expert. About half of all the observations have been identified reliably to the species level and received Research Grade status. Of those, 90 species (195 records) represented records of taxa new to their respective regions: 876 records of 53 species of protected species provide important data for conservation programmes. The other half of the observations consists of records still under-identified for various reasons: poor quality photographs, complex taxa (impossible to identify without microscopic or molecular study). or lack of experts in a particular taxonomic group. The Discussion section summarises the pros and cons of the use of crowdsourcing for the study and conservation of regional fungal diversity, and summarises the dispute on this subject among mycologists. Further research initiatives involving crowdsourcing data must focus on an increase in the quality of observations and strive to introduce the habit of collecting voucher specimens among the community of amateurs. The timely feedback from experts is also important to provide quality and the increase of personal involvement.Peer reviewe

Investigation of the electron-hole and interstitialvacancy processes in MgO and LiF single crystals using thermoactivation spectroscopy methods

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Käesolevaks ajaks on LiF ja Al2O3 baasil loodud hästitöötavad termoluminestsentsdosimeetrid röntgen- ja γ-kiirguse doosi mõõtmiseks, on olemas dosimeetrid elektronide, prootonite, ioonide ja aeglaste neutronite voo intensiivsuse ja doosi määramiseks. Senini puudub aga sobiv dosimeeter, mis võimaldaks määrata kiirete neutronite osakaalu neutronite ja γ-kiirguse summaarses kiirgusvoos. Selle praktikas sageli esineva ülesande lahendamine on oluline, sest võrdse doosi korral on neutronite inimorganismi kahjustav toime γ-kiirguse omast ligi 20 korda suurem. Käesolevas töös on uuritud selleks sobiva dosimeetri loomise võimalusi, seda eelkõige kiirituskindla kristalli MgO baasil. Lähtepunktiks oli meie poolt tehtud avastus, et kiirete neutronite poolt võresõlmest välja löödud hapniku aatomid moodustavad tsentreid, mille termiliselt lagunemisel tekib luminestsents. Viidi läbi ka MgO ja tuntud termoluminestsentsdosimeetri alusmaterjali LiF võrdlev uurimus. Vaatluse all olid defektide teke ja lagunemine mõlemas materjalis, uurimisel kasutati termoaktivatsiooniga kombineeritud luminestsentsi, neeldumise ja EPR meetodeid temperatuurivahemikus 5800 K. Uurimuse põhitulemused on kokkuvõtlikult järgnevad: 1. Kiirete neutronite või raskete ioonide poolt MgO kiiritamisel tekkivatest interstitsiaalidest osa lokaliseerub katioonvakantsi kõrval asuva molekulaarse iooni 2 O kujul (vc 2 O ehk H-tsenter). Selle osa suurus sõltub kiirituse liigist ning on neutronite korral ~50%. 2. Seda protsessi võib vaadelda kui võresõlmede vahelise hapniku haaramist V-tsentri (katioonvakantsi kõrvale haaratud auk vch pluss võimalik lähedalasuv lisandiioon) poolt. Sellele vastavalt leidub igale V-tsentrile vastav H-tsenter, mille konkreetsed omadused sõltuvad temaga geneetiliselt seotud V-tsentrist. 3. H-tsentrite termiline lagunemine toimub ~700 K juures võresõlmede vahelise hapniku aatomi ning augu eraldumise teel. H-tsentri lagunemisel on jälgitav augu rekombinatsioonil tekkiv termostimuleeritud luminestsents (TSL), mille intensiivsus on võrdeline tekkinud ja lagunenud H-tsentrite arvuga. Luminestsents tekib tsentri lagunemisel vabanenud augu ning interstitsiaali ning ühekordselt laetud anioonvakantsi (F+-tsenter ehk anioovakants + elektron) 64 rekombinatsioonil vabanenud augu rekombinatsioonil lisandiioonidele (sel temperatuuril põhiliselt Cr2+) haaratud elektronidega. 4. Jälgitud termoluminestsentsi dosimeetriliste omaduste sobivuse uuring näitas, et kui meetodi selektiivsus on kõrge (γ-kiiritamisel H-tsentreid ei teki) ja doosikadu (fading) praktiliselt puudub (tsentri lagunemistemperatuur on kõrge), siis antud meetodi tundlikkus on personaaldosimeetria jaoks liiga madal: ta on rakendatav neutronite voogude ≥1016 n/cm2 korral. Põhjuseks on asjaolu, et sel temperatuuril jälgitav soojuskiirguslik foon oluliselt kattub TL piigi kiirgusega (Cr3+ kiirgab 730 nm juures). 5. Berülliumiga legeeritud MgO kristallides lokaliseeruvad augud Be2+ kõrvale, moodustades [Be]+ tsentreid. Elektronide rekombinatsioonil nende aukudega tekib kõrvalasuva Be iooni poolt häiritud hapniku ioonide kiirgus maksimumiga 6,2 eV ning poollaiusega ~0,8 eV. [Be]+ tsenter laguneb termiliselt 195 K juures, vabastades augu. 6. Sünteesiti elavhõbesarnaste (4s2) Ge2+ ioonidega lisandatud MgO monokristallid. Nende ergastamisel on jälgitav intensiivne sinine luminestsents (toatemperatuurilise elektronergastuse korral on luminestsentsiriba maksimum 3,2 eV). Ergastusspektri mõõtmine näitas, et luminestsents tekib Ge2+ 4s2 tüüpi ioonide otsesel ergastamisel. Luminestsents on jälgitav laias temperatuurivahemikus 4650 K ning vastab 3P11S0 üleminekule vabas Ge2+ ioonis. Luminestsentsi kõrge temperatuuriline stabiilsus teeb ta eriti sobivaks termoluminestsentsi mõõtmiseks temperatuurini kuni 500 K. 7. LiF kristallide röntgenkiiritamisel 6 või 80 K juures tekivad nii anioonkui katioonergastuste lagunemisel stabiilsed anioonsed Frenkeli defektid (Ftsentrid ja H-interstitsiaalid). Leiti, et F- ja F-tsentrid, autolokaliseeritud augud ja aniooninterstitsiaalid moodustavad ruumiliselt korreleeritud defektirühmi (tripletid FHVk ja FIVk), mis lagunevad termiliselt 716 K juures. Tripletisiseste defektide tunnel-ümberlaadumisega kaasneb luminestsents 3,4 eV (F→Vk), 5,4 eV (F→Vk), ja 3 eV (F→H) juures. TSL piirkonnas 7 16 K lahutati komponentideks, mis on kirjeldatavad 1. järku kineetika, aktivatsioonienergia Ea ja sagedusfaktoriga p0. 8. LiF 420450 K TSL-piike on kaua ja laialdaselt kasutatud personaalgammadosimeetrias. Peale nende dosimeetriliste piikide leiti 300 K kiiritatud LiF-s kõrgtemperatuurilisi piike piirkonnas 600750 K. Nende piikide intensiivsus on eriti suur eelnevalt 0,82,4 GeV energiaga Kr, Au ja U ioonidega kiiritatud kristallides. Sellised ioonid põhjustavad piki trekki suurt elektronergastuste tihedust. Intensiivseima piigi maksimum asub 725 K ning vastab 1. järku protsessile parameetritega Ea = 2,495 eV ning p0 = 5×1016 s–1. Anomaalselt kõrget p0 väärtust tõlgendatakse kui F-tsentri kiire hüppelise migratsiooni ning F-tsentri elektroni ning mingi Mg lisandiga defektil lokaliseeritud augu tunnelrekombinatsiooni tulemust. Mg ioonide olemasolu näitab tüüpiline ~4,4 eV nanomõõtmeliste Mg-kolloidi osakeste (sulamistäpp ~950 K) neeldumisriba kõigis kiiritatud ja üle 700 K kuumutatud LiF kristallides.Novel materials are needed for nuclear energetics: radiation-resistant construction materials for reactors as well as radiation-sensitive ones for dosimeters. The prospects to elaborate a selective dosimeter of fast neutrons in mixed gamma-neutron fields on the basis of highly resistant MgO have been analyzed. A study was based on our previously established fact that fast neutrons create oxygen-related centres via a knock-out mechanism and the thermal annealing of the centres causes thermoluminescence (TSL). High resistance of MgO provides the selectivity of this method gamma-rays do not create these defects. According to our investigations, about a half of anion interstitials created by the irradiation of MgO with fast neutron or heavy ions are localized in a form of an molecular ion nearby a cation vacancy (H centres). Thermal destruction of H centres (~700 K) is accompanied by TSL the intensity of which is proportional to the number of H centres. The TSL arises at the recombination of the holes, released during H centres destruction at the interaction of interstitials and single-charged anion vacancies (F+ centres), with the electrons still localized at impurities (mainly Cr2+). It turned out that this method is a selective one but has insufficient sensitivity (≥1016 n/cm2) for the use in personal dosimetry due to a high background level at the used temperatures and spectral region. In contrast to MgO, LiF single crystals are sensitive to radiation, electron-hole (e-h) processes cause TSL at 400-550 K that is used in gamma-dosimetry. The creation and thermal annealing (4-800 K) of Frenkel defects have been investigated in LiF crystals irradiated with electrons, x-rays or heavy ions. It is proved that the TSL peak at ~13 K is connected with the e-h tunnel recombination within the triplets of spatially correlated defects, while the TSL at 600-800 K is caused by both e-h and ionic processes. A comparison of radiation defects in MgO and LiF with very different melting temperature (3200 and 1120 K) is performed