Tableau-based translation from first-order logic to modal logic

We define a procedure for translation of a given first-order formula to an equivalent modal formula, if such exists, by using tableau-based bisimulation invariance test. Previously developed tableau procedure tests bisimulation invariance of a given first-order formula, and therefore tests whether that formula is equivalent to the standard translation of some modal formula. Using a closed tableau as the starting point, we show how an equivalent modal formula can be effectively obtained

Recycling of Prydniprovska thermal power plant fly ash

Purpose. To confirm experimentally the feasibility of complete fly ash recycling at Prydniprovska Thermal Power Plant (TPP) by its refining into industrially valuable products using gravity classification of dry ash from electrostatic precipitators and water-gravity separation of ash from a dump. Methods. Classification of fly ash has been carried out on the modernized processing equipment in the laboratory in two ways. First, ash pneumatic separation was done directly from the electrostatic precipitators using a specially selected vibrating screen. The second way involved hydro-separation of the original product from the ash dump using the upgraded centrifuges and hydrocyclones. Findings. Technological solution for complex processing of fly ashes, based on the “dry” gravitational separation of ash from electrostatic precipitators and “wet” gravitational separation of ash from thermal power plants and storage dumps has been developed. It is established that the addition of active ash up to 33% to 1 m3 of concrete allows to save up to 25% of cement and increase strength of concrete structures up to 5%. Addition of products manufactured from thermal power plants waste for production of building materials allows to reduce the share of energy consumption up to 20 – 25%, which is essential for the competitiveness of construction products. A mixture of alumina-silica products can reduce clay usage in metallurgical industry to 50%. Carbon products are cheap substitutes for production of certain kinds of sorbents. The proposed project solution allows to reduce resource consumption, decrease human impact on the environment, and increase energy potential of the region. Originality. The time dependence related to surface activity decrease of the resulting recycling products from the dry fly ash directly from electrostatic precipitators has been established. Recycling of fly ash into industrially useful products by dry gravity separation allows to achieve the best physical parameters of the raw materials with the highest specific activity. Practical implications. Implementation of the research results will be instrumental in receiving such industrial products as: components in the manufacture of building materials (concrete, foam and aerated concrete, brick), heat insulating material, raw materials for steel industry, sorbents for chemical industry and deoxidants for metallurgical industry. The proposed technological solution is completely environmentally safe and non-waste.Цель. Экспериментально подтвердить возможность полной утилизации зол-уносов Приднепровской ТЭС путем ее переработки в промышленно ценные продукты, используя сухую гравитационную классификацию золы с электрофильтров и водно-гравитационное разделение золы из золоотвала. Методика. Классификация зол-уносов произведена в лабораторных условиях с применением модернизированного обогатительного оборудования по двум направлениям: пневморазделение золы непосредственно с электрофильтров с применением специально подобранного вибрационного грохота; гидроразделение исходного продукта из золоотвала с использованием модернизированных центрифуг и гидроциклонов. Результаты. Разработано технологическое решение комплексной переработки зол-уноса, основанное на “сухом” гравитационном разделении золы с электрофильтров и “мокром” гравитационном разделении золы с накопителей и отвалов ТЭС. Установлено, что введение до 33% активной золы на 1 м3 бетона дает возможность экономить до 25% цемента и повышать прочность бетонных конструкций до 5%. Введение продуктов, полученных из отходов ТЭС, в производство стройматериалов позволит снизить долю энергозатрат до 20 – 25%, что является главным условием конкурентоспособности строительной продукции. Смесь глинозем-кремнистых продуктов позволяет снизить использование глин в металлургии до 50%. Углеродные продукты являются дешевыми заменителями для производства отдельных видов сорбентов. Разработанное проектное решение позволяет сократить ресурсопотребление, повысить энергетический потенциал региона и уменьшить техногенную нагрузку на окружающую среду. Научная новизна. Установлена временная зависимость снижения поверхностной активности полученных продуктов переработки из сухой золы-уноса непосредственно с электрофильтров. При переработке золы-уноса в промышленно пригодные продукты сухим гравитационным разделением достигаются наилучшие физические параметры сырья с наибольшей удельной активностью. Практическая значимость. Реализация результатов исследований позволит получить промышленную продукцию: компоненты при изготовлении строительных материалов (бетон, пено- и газобетон, кирпич), теплоизоляционного материала, сырья для сталелитейной отрасли, сорбентов в химической промышленности и раскислителей в металлургической. Предложенное технологическое решение является полностью экологически безопасным и безотходным.Мета. Експериментально підтвердити можливість повної утилізації зол-винесення Придніпровської ТЕС шляхом її переробки у промислово цінні продукти, використовуючи суху гравітаційну класифікацію золи з електрофільтрів і водно-гравітаційне розділення золи із золовідвалу. Методика. Класифікація зол-винесення проведена в лабораторних умовах із застосуванням модернізованого обладнання за двома напрямками: пневморозділення золи безпосередньо з електрофільтрів із застосуванням спеціально підібраного вібраційного грохота; гідророзділення вихідного продукту із золовідвала з використанням модернізованих центрифуг та гідроциклонів. Результати. Розроблене технологічне рішення комплексної переробки зол-винесення, що засноване на “сухому” гравітаційному поділі золи з електрофільтрів та “мокрому” гравітаційному поділі золи із накопичувачів та відвалів ТЕС. Встановлено, що введення до 33% активної золи на 1 м3 бетону дає можливість економити до 25% цементу й підвищувати міцність бетонних конструкцій до 5%. Додавання продуктів, отриманих з відходів ТЕС, у виробництво будматеріалів дозволить знизити частку енерговитрат до 20 – 25%, що є головною умовою конкурентоспроможності будівельної продукції. Суміш глинозем-кременистих продуктів дозволяє знизити використання глин у металургії до 50%. Вуглецеві продукти є дешевими замінниками для виробництва окремих видів сорбентів. Розроблене проектне рішення дозволяє скоротити споживання ресурсів, підвищити енергетичний потенціал регіону та зменшити техногенне навантаження на навколишнє середовище. Наукова новизна. Встановлено залежність зменшення у часі питомої активності отриманих продуктів переробки із сухої золи-винесення безпосередньо з електрофільтрів. При переробці золи-винесення в промислово придатні продукти сухим гравітаційним поділом досягаються найкращі фізичні параметри сировини з найбільшою питомою активністю. Практична значимість. Реалізація результатів досліджень дозволить отримати промислову продукцію: компоненти для виготовлення будівельних матеріалів (бетон, піно-і газобетон, цеглу), теплоізоляційного матеріалу, сировини для сталеливарної галузі, сорбентів у хімічній промисловості та розкислювачів у металургійній. Запропоноване технологічне рішення є повністю екологічно безпечним та безвідходним.Авторы выражают искрению благодарность директору ООО НКП “Геоинтек” канд. геол.-мин. наук С.Е. Поповченко за предоставленное оборудование, помощь в проведении экспериментов и консультации

Transition from Fireball to Poynting-flux-dominated Outflow in Three-Episode GRB 160625B

The ejecta composition is an open question in gamma-ray bursts (GRB) physics. Some GRBs possess a quasi-thermal spectral component in the time-resolved spectral analysis, suggesting a hot fireball origin. Others show a featureless non-thermal spectrum known as the "Band" function, consistent with a synchrotron radiation origin and suggesting that the jet is Poynting-flux-dominated at the central engine and likely in the emission region as well. There are also bursts showing a sub-dominant thermal component and a dominant synchrotron component suggesting a likely hybrid jet composition. Here we report an extraordinarily bright GRB 160625B, simultaneously observed in gamma-rays and optical wavelengths, whose prompt emission consists of three isolated episodes separated by long quiescent intervals, with the durations of each "sub-burst" being $\sim$ 0.8 s, 35 s, and 212 s, respectively. Its high brightness (with isotropic peak luminosity L$_{\rm p, iso}\sim 4\times 10^{53}$ erg/s) allows us to conduct detailed time-resolved spectral analysis in each episode, from precursor to main burst and to extended emission. The spectral properties of the first two sub-bursts are distinctly different, allowing us to observe the transition from thermal to non-thermal radiation between well-separated emission episodes within a single GRB. Such a transition is a clear indication of the change of jet composition from a fireball to a Poynting-flux-dominated jet.Comment: Revised version reflecting the referees' comments. 27 pages, 11 figures, 5 tables. The final edited version will appear in Nature Astronom

Eight exoplanet candidates in SAO survey

Here we present eight new candidates for exoplanets detected by the transit method at the Special Astrophysical Observatory of the Russian Academy of Sciences. Photometric observations were performed with a 50-cm robotic telescope during the second half of 2020. We detected transits with depths of $\Delta m = 0.056-0.173^m$ and periods $P = 18.8^h-8.3^d$ in the light curves of stars with magnitudes of $m = 14.3-18.8^m$. All considered stars are classified as dwarfs with radii of $R_* = 0.4-0.6 R_{sun}$ (with the uncertainty for one star up to $1.1 R_{sun}$). We estimated the candidate radii (all are greater than 1.4 times the Jovian radius), semi-major axes of their orbits ($0.012-0.035 AU$), and other orbital parameters by modelling. We report the light curves with transits for two stars obtained in 2022 based on individual observations.Comment: 16 pages, 14 figures, 3 table

Transition from fireball to Poynting-flux-dominated outflow in the three-episode GRB 160625B

The ejecta composition is an open question in gamma-ray burst (GRB) physics . Some GRBs possess a quasi-thermal spectral component in the time-resolved spectral analysis , suggesting a hot fireball origin. Others show a featureless non-thermal spectrum known as the Band function , consistent with a synchrotron radiation origin and suggesting that the jet is Poynting-flux dominated at the central engine and probably in the emission region as well . There are also bursts showing a sub-dominant thermal component and a dominant synchrotron component , suggesting a probable hybrid jet composition . Here, we report an extraordinarily bright GRB 160625B, simultaneously observed in gamma-ray and optical wavelengths, whose prompt emission consists of three isolated episodes separated by long quiescent intervals, with the durations of each sub-burst being approximately 0.8 s, 35 s and 212 s, respectively. Its high brightness (with isotropic peak luminosity L ≈ 4 × 10 erg s) allows us to conduct detailed time-resolved spectral analysis in each episode, from precursor to main burst and to extended emission. The spectral properties of the first two sub-bursts are distinctly different, allowing us to observe the transition from thermal to non-thermal radiation between well-separated emission episodes within a single GRB. Such a transition is a clear indication of the change of jet composition from a fireball to a Poynting-flux-dominated jet.B.-B.Z. thanks Y.-Z. Fan, Y.-Z. Wang, H. Wang, K. D. Alexander and D. Lazzati for helpful discussions. We are grateful to K. Hurley, I. Mitrofanov, A. Sanin, M. Litvak and W. Boynton for the use of Mars Odyssey data in the triangulation. We acknowledge the use of the public data from the Swift and Fermi data archives. B.-B. Z. and A.J. C.-T. acknowledge support from the Spanish Ministry Projects AYA2012-39727-C03-01 and AYA2015-71718-R. Part of this work made use of B.-B.Z.'s personal Interactive Data Language (IDL) code library ZBBIDL and personal Python library ZBBPY. The computation resources used in this work are owned by Scientist Support LLC. B.Z. acknowledges NASA NNX14AF85G and NNX15AK85G for support. Z. G. D. acknowledges the National Natural Science Foundation of China(NSFC) (grant 11573014). Y.-D. H. acknowledges support by China Scholarships Council (grant 201406660015). Mini-MegaTORTORA belongs to Kazan Federal University, and the work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University. A. P., E.M., P. M. and A.V. are grateful to the Russian Foundation for Basic Research (grant 17-02-01388) for partial support. A. P. and S.B.P. acknowledge joint BRICS (Brazil, Russia, India, China and South Africa) grant RFBR 17-52-80139 and 388-ProFChEAP for partial support. R. I. is grateful to grant RUSTAVELI FR/379/6300/ 14 for partial support. Observations on Mini-MegaTORTORA are supported by the Russian Science Foundation (grant 14-50-00043). A.V.F. and A. M. thank the Russian Science Foundation (grant 14-50-00043). L.M. and A.F.Z. acknowledge support from INTA-CEDEA ESAt personnel hosting the Pi of the Sky facility at the BOOTES-1 station. H. G. and X.-Y.W. acknowledge NSFC (grants 11603003 and 11625312, respectively). Z. G. D., X.-F. W., B.Z., X.-Y. W.,L.S. and F.-W.Z. are also supported by the 973 program (grant 2014CB845800). F.-W.Z. is also supported in part by the NSFC (grants U1331101 and 11163003), the Guangxi Natural Science Foundation (grant 2013GXNSFAA019002) and the project of outstanding young teachers' training in higher education institutions of Guangxi. L.S. acknowledges support by the NSFC (grant 11103083) and the Joint NSFC-ISF Research Program (grant 11361140349). S.O. acknowledges the support of the Leverhulme Trust. S.J. acknowledges support from Korea Basic Science Research Program through NRF-2014R1A6A3A03057484 and NRF-2015R1D1A4A01020961, and I. H. P. through NRF-2015R1A2A1A01006870 and NRF-2015R1A2A1A15055344. R. A., D. F. and D. S. acknowledge support from RSF (grant 17-12-01378). A. K. acknowledges the Science and Education Ministry of Kazakhstan (grant 0075/GF4).Peer reviewe

Transition from fireball to Poynting-flux-dominated outflow in three-episode GRB 160625B [submitted version]

The ejecta composition of gamma-ray bursts (GRBs) is an open question in GRB physics. Some GRBs possess a quasi-thermal spectral component in the time-resolved spectral analysis, suggesting a hot fireball origin. Some others show an essentially feature-less non-thermal spectrum known as the "Band" function, which can be interpreted as synchrotron radiation in an optically thin region, suggesting a Poynting-flux-dominated jet composition. Here we report an extraordinarily bright GRB 160625B, simultaneously observed in gamma-rays and optical wavelengths, whose prompt emission consists of three dramatically different isolated episodes separated by long quiescent intervals, with the durations of each "sub-burst" being ∼ 0.8 s, 35 s, and 212 s, respectively. The high brightness (with isotropic peak luminosity Lp,iso∼4×1053 erg/s) of this GRB allows us to conduct detailed time-resolved spectral analysis in each episode, from precursor to the main burst and extended emission. Interestingly, the spectral properties of the first two sub-bursts are distinctly different, which allow us for the first time to observe the transition from thermal to non-thermal radiation in a single GRB. Such a transition is a clear indication of the change of jet composition from a fireball to a Poynting-flux-dominated jet

High-Resolution Fiber-Fed Spectrograph for the 6-m Telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences: Assessment of Efficiency

International audienceWe report the results of laboratory tests of the first version of the high-resolution fiber-fed spectrograph designed for the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS). During laboratory tests a spectral resolution of about 70 000 was achieved. The peak efficiency of the entire optical path of the spectrograph (without light losses at the CCD, primary mirror of the 6-m telescope, and in the atmosphere) at 620 nm and with the equivalent slit widths of the 1″.5 and 0″.75 are equal to 8% and 4%, respectively. The resolving power R = 70 000 and 100 000 can be reached with the sky aperture 0″.75 and 0″.4 respectively. In the current version of the spectrograph these regimes of operation are implemented by mechanic aperturing of the slit. A dedicated projecting camera has been developed and is currently manufactured to operate with a collimated 200-mm diameter beam, which will make it possible to increase the spectral resolution up to 100 000. A two-beam image slicer will be used to maintain the luminous efficiency of the instrument at least at the 6% level