Purpose. Comparative evaluation of aeroacoustic characteristics of the axial compressor stages with a single and equivalent tandem impeller. Methodology. The research was performed using the ...numerical experiment. The flow parameters in the stage of the axial compressor were calculated by solving the non-stationary system of Navier - Stokes equations. The equations were closed by the model of turbulent viscosity SST. The stage of the compressor consisted of inlet guide vanes, the impeller and the guide vanes. The impeller of the modified axial compressor stage is designed as an equivalent tandem row. Acoustic sources of the axial compressor stage were calculated using the Ffowcs Williams - Hawkings equation. Findings. The results of a comparative evaluation of the aeroacoustic characteristics of the axial compressor stages with a single and equivalent double-row impeller are obtained. The use of a tandem row instead of an equivalent single row in the impeller of the axial compressor stage makes it possible to increase the pressure ratio by 1-15 %. In the design mode, the pressure ratio is increased by 8.5 %. A stage with a tandem impeller has greater acoustic efficiency than a compressor stage with a single impeller. The obtained results demonstrate a significant decrease in the acoustic pressure of the dipole source. In the design mode, the acoustic pressure of the dipole source decreases by more than 70 %, the acoustic pressure of the quadrupole source decreases by more than 10 %. Originality. For the first time the results of a comprehensive study of the aerodynamic and acoustic characteristics of the axial compressor stage were obtained. The results allow estimating the efficiency of application of tandem row in the impeller of the low loaded subsonic stage of the axial compressor. Practical value. The received recommendations can be used while designing impeller machines with a low level of acoustic emission.
We search for an indirect signal of dark matter through very high-energy γ rays from the Wolf-Lundmark-Melotte (WLM) dwarf irregular galaxy. The pair annihilation of dark matter particles would ...produce Standard Model particles in the final state such as γ rays, which might be detected by ground-based Cherenkov telescopes. Dwarf irregular galaxies represent promising targets as they are dark matter dominated objects with well-measured kinematics and small uncertainties on their dark matter distribution profiles. In 2018, the five-telescopes of the high energy stereoscopic system observed the dwarf irregular galaxy WLM for 18 hours. We present the first analysis based on data obtained from an imaging atmospheric Cherenkov telescope for this subclass of dwarf galaxy. As we do not observe any significant excess in the direction of WLM, we interpret the result in terms of constraints on the velocity-weighted cross section for dark matter pair annihilation ⟨ σv ⟩ as a function of the dark matter particle mass for various continuum channels, as well as the prompt γγ emission. For the τ+ τ− channel, the limits reach a ⟨ σv ⟩ value of about 4 × 10−22 cm3 s−1 for a dark matter particle mass of 1 TeV. For the prompt γγ channel, the upper limit reaches a ⟨ σv ⟩ value of about 5 × 10−24 cm3 s−1 for a mass of 370 GeV. These limits represent an improvement of up to a factor 200, with respect to previous results for the dwarf irregular galaxies for TeV dark matter search.
Ссылка для цитирования: Литолого-минералогическое обоснование стратификации нижнеберёзовской подсвиты Медвежьего и Вынгапуровского месторождений / Л.Г. Ананьева, А.А. Дорошенко, А.А. Дорошенко, Д.И. ...Изосимов, Я.О. Карымова, И.В. Качинскас, М.В. Коровкин, С.В. Нерсесов, О.В. Постникова // Известия Томского политехнического университета. Инжиниринг георесурсов. – 2022. – Т. 333. – № 5. – С. 89-99.
Актуальность. В настоящее время изучение надсеноманских отложений, в том числе и сложенных кремнистыми породами отложений нижнеберёзовской подсвиты коньяк-сантонского возраста, из разряда теоретического интереса перешло в разряд практически важных исследований. Это связано с тем, что промышленная газоносность подтверждена на шести участках (Ван-Еганский – пласт НБ1, Вынгапуровский – НБ4, Медвежий НБ3–НБ4, Ново-Часельский – НБ3, Комсомольский НБ1, Харампурский НБ1). Выделяется четыре пласта нижнеберёзовской подсвиты (горизонт НБ), однако критериев определения границ этих пластов пока не выявлено. В настоящей работе дано обоснование литолого-минералогических и промыслово-геофизических критериев стратиграфического расчленения разреза нижнеберёзовской подсвиты. Объектом исследования является берёзовская свита, отложения которой на севере Западной Сибири содержат значительные ресурсы газа, рассматриваемые как резерв «продления жизни» месторождений при выработке высокопродуктивных отложений сеномана. Цель: повышение эффективности геологоразведочных работ по выявлению залежей газа в кремнистых породах сенона за счёт уточнения стратиграфического строения пород берёзовской свиты. Методы. Расчленение разрезов проводилось по скважинам, пробуренным в последние годы, со сплошным отбором керна и с расширенным комплексом геофизических исследований скважин (ГИС), включающим электрические, радиоактивные, акустические, ядерно-магнитные методы. Минеральный состав определялся путём изучения керна методами рентгеноструктурного анализа (более 300 образцов), инфракрасной спектроскопии (220 образцов). Состав химических элементов в породах устанавливался методами рентгенофлуоресцентного анализа (более 300 образцов) и масс-спектрометрии с индуктивно-связанной плазмой (70 образцов). Результаты. Показано, что граница между пластами НБ2 и НБ3 не имеет однозначных критериев по ГИС. На Медвежьем месторождении эта граница определяется по скачкообразному изменению показаний ядерно-магнитного и акустического каротажей, на Вынгапуровском же месторождении таких скачкообразных изменений на кривых этих методов не отмечается. Показано, что граница между пластами НБ2 и НБ3 имеет чёткую характеристику по минеральному составу пород и определяется резким снижением доли цеолитов (клиноптилолита) при переходе от НБ2 к НБ3. Вместе со снижением содержания клиноптилолита на границе между пластами НБ2 и НБ3 происходит и резкое изменение в химическом составе пород, в частности, отмечается резкое снижение доли стронция. Такая тенденция к снижению доли клиноптилолита и стронция в породах может быть объяснена затуханием вулканической деятельности на юго-востоке Западной Сибири.
The Fe:Zn(1-x)Mg(x)Se (x = 0.19, 0.27, and 0.38) solid solutions spectroscopic properties were investigated and laser oscillations were achieved for the first time. The increase of the magnesium ...concentration in the Fe:ZnMgSe crystal was shown to result in an almost similar long wavelength shift of both absorption and fluorescence spectra of about 60 nm per each 10% of magnesium. With the Fe:ZnMgSe crystal temperature decrease, the fluorescence spectrum maximum shifts towards shorter wavelength resulting mainly from strong narrowing of the longest wavelength fluorescence line. Laser radiation wavelength dependence on the magnesium concentration as well as on temperature was observed. The Fe:ZnMgSe x = 0.38 laser oscillation wavelength increased from 4780 nm at 80 K to 4920 nm at 240 K using the optical resonator without any intracavity spectrally-selective element. In comparison with the Fe:ZnSe laser operating in similar conditions, these wavelengths at both temperatures were shifted by about 500 nm towards mid-IR region.
As multifunctional regulators of physiological processes, phytohormones play an important role in the regulation of expression of the plastid genome and chloroplast biogenesis. Hormones can directly ...regulate the expression of genes localized in the chloroplast genome. However, many components of the plastid transcription apparatus are encoded by nuclear rather than plastid genes. It remains obscure whether these nuclear genes are subject to hormonal regulation. This is the first study to show that phytohormones exert differential effects on the expression of nuclear genes of the transcription machinery of the
Arabidopsis thaliana
plastome. RT-PCR analysis showed that the level of transcripts of the majority of studied genes was activated by
trans
-zeatin but decreased under the influence of ABA, methyl jasmonate, and salicylic acid, whereas ethylene had no significant effect, and the effects of brassinolide depended on the illumination conditions. The results of this study indicate that the hormonal regulation of the plastome expression can be mediated by differential regulation of the nuclear genes encoding plastid transcription machinery components.
Results for new fluoride ceramics doped with praseodymium ions in which, to the best of our knowledge, for the first time a laser in the visible spectral range (639 nm) was obtained under GalnN blue ...laser diode optical pumping. In our experiments, CW operation with lasing threshold less than 100 mW of absorbed pump power and slope efficiency exceeding 9% was realized.
We report on a detailed spectral analysis of emission from X-ray pulsar 4U 1901+03 using data obtained by the Insight-HXMT and
NuSTAR
observatories during the 2019 outburst of the source. Thanks to ...the extensive coverage of the outburst by Insight-HXMT, we were able to investigate the spectral evolution of the source as a function of flux, and compare these results to the previous reports, focusing on the properties of a putative absorption feature at around 10 keV. In particular, we demonstrate that the broadband X-ray continuum of 4U 1901+03 can be well described with a two-component continuum model without an absorption line at 10 keV, which casts doubt on its interpretation as a cyclotron line. The high quality of the data also allowed us to perform both phase-averaged and phase-resolved spectral analyses as a function of luminosity. Finally, we performed a detailed investigation of another absorption feature in the spectrum of the source around 30 keV recently reported in the
NuSTAR
data. We show that this feature appears to be significantly detected both in phase-averaged and phase-resolved spectra irrespective of the continuum model.
The phase composition of aluminum alloys of the Al – Ca – Ni – Sc system containing 0.3 wt.% Sc is studied. It is shown that the aluminum solid solution may be in equilibrium not only with binary ...phases (Al
4
Ca, Al
3
Sc and Al
3
Ni) but also with a ternary Al
9
NiCa compound. The temperature of attainment of maximum hardening due to precipitation of nanoparticles of phase Al
3
Sc is determined for all the alloys studied. Principal possibility of creation of castable alloys based on an (Al) + Al
4
Ca + Al
9
NiCa eutectic, the hardening heat treatment of which does not require quenching, is substantiated.
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