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Saha S, Nagaraj N, Mathur A, Yedida R, H R S. Evolution of novel activation functions in neural network training for astronomy data: habitability classification of exoplanets. THE EUROPEAN PHYSICAL JOURNAL. SPECIAL TOPICS 2020; 229:2629-2738. [PMID: 33194093 PMCID: PMC7651829 DOI: 10.1140/epjst/e2020-000098-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/02/2020] [Indexed: 06/11/2023]
Abstract
Quantification of habitability is a complex task. Previous attempts at measuring habitability are well documented. Classification of exoplanets, on the other hand, is a different approach and depends on quality of training data available in habitable exoplanet catalogs. Classification is the task of predicting labels of newly discovered planets based on available class labels in the catalog. We present analytical exploration of novel activation functions as consequence of integration of several ideas leading to implementation and subsequent use in habitability classification of exoplanets. Neural networks, although a powerful engine in supervised methods, often require expensive tuning efforts for optimized performance. Habitability classes are hard to discriminate, especially when attributes used as hard markers of separation are removed from the data set. The solution is approached from the point of investigating analytical properties of the proposed activation functions. The theory of ordinary differential equations and fixed point are exploited to justify the "lack of tuning efforts" to achieve optimal performance compared to traditional activation functions. Additionally, the relationship between the proposed activation functions and the more popular ones is established through extensive analytical and empirical evidence. Finally, the activation functions have been implemented in plain vanilla feed-forward neural network to classify exoplanets. The mathematical exercise supplements the grand idea of classifying exoplanets, computing habitability scores/indices and automatic grouping of the exoplanets converging at some level.
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Affiliation(s)
- Snehanshu Saha
- CSIS and APPCAIR, BITS Pilani K K Birla, Goa Campus, Sancoale, India
| | - Nithin Nagaraj
- Consciousness Studies Programme, National Institute of Advanced Studies, Bengaluru, India
| | - Archana Mathur
- Nitte Meenakshi Institute of Technology, Bengaluru, India
| | | | - Sneha H R
- Nitte Meenakshi Institute of Technology, Bengaluru, India
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Niu H, Oganov AR, Chen XQ, Li D. Prediction of novel stable compounds in the Mg-Si-O system under exoplanet pressures. Sci Rep 2015; 5:18347. [PMID: 26691903 PMCID: PMC4686916 DOI: 10.1038/srep18347] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 10/22/2015] [Indexed: 11/09/2022] Open
Abstract
The Mg-Si-O system is the major Earth and rocky planet-forming system. Here, through quantum variable-composition evolutionary structure explorations, we have discovered several unexpected stable binary and ternary compounds in the Mg-Si-O system. Besides the well-known SiO2 phases, we have found two extraordinary silicon oxides, SiO3 and SiO, which become stable at pressures above 0.51 TPa and 1.89 TPa, respectively. In the Mg-O system, we have found one new compound, MgO3, which becomes stable at 0.89 TPa. We find that not only the (MgO)x·(SiO2)y compounds, but also two (MgO3)x·(SiO3)y compounds, MgSi3O12 and MgSiO6, have stability fields above 2.41 TPa and 2.95 TPa, respectively. The highly oxidized MgSi3O12 can form in deep mantles of mega-Earths with masses above 20 M⊕ (M⊕:Earth’s mass). Furthermore, the dissociation pathways of pPv-MgSiO3 are also clarified, and found to be different at low and high temperatures. The low-temperature pathway is MgSiO3 ⇒ Mg2SiO4 + MgSi2O5 ⇒ SiO2 + Mg2SiO4 ⇒ MgO + SiO2, while the high-temperature pathway is MgSiO3 ⇒ Mg2SiO4 + MgSi2O5 ⇒ MgO + MgSi2O5 ⇒ MgO + SiO2. Present results are relevant for models of the internal structure of giant exoplanets, and for understanding the high-pressure behavior of materials.
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Affiliation(s)
- Haiyang Niu
- Moscow Institute of Physics and Technology, 9 Institutskiy Lane, Dolgoprudny city, Moscow Region 141700, Russia.,Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.,Department of Geosciences, Center for Materials by Design, and Institute for Advanced Computational Science, State University of New York, Stony Brook, NY 11794-2100
| | - Artem R Oganov
- Moscow Institute of Physics and Technology, 9 Institutskiy Lane, Dolgoprudny city, Moscow Region 141700, Russia.,Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel St., Moscow 143026, Russia.,Department of Geosciences, Center for Materials by Design, and Institute for Advanced Computational Science, State University of New York, Stony Brook, NY 11794-2100.,School of Materials Science, Northwestern Polytechnical University, Xi'an 710072, China
| | - Xing-Qiu Chen
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Dianzhong Li
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
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Jenkins JM, Twicken JD, Batalha NM, Caldwell DA, Cochran WD, Endl M, Latham DW, Esquerdo GA, Seader S, Bieryla A, Petigura E, Ciardi DR, Marcy GW, Isaacson H, Huber D, Rowe JF, Torres G, Bryson ST, Buchhave L, Ramirez I, Wolfgang A, Li J, Campbell JR, Tenenbaum P, Sanderfer D, Henze CE, Catanzarite JH, Gilliland RL, Borucki WJ. DISCOVERY AND VALIDATION OF Kepler-452b: A 1.6R⨁SUPER EARTH EXOPLANET IN THE HABITABLE ZONE OF A G2 STAR. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-6256/150/2/56] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kuhn JR, Berdyugina SV. Global warming as a detectable thermodynamic marker of Earth-like extrasolar civilizations: the case for a telescope like Colossus. INTERNATIONAL JOURNAL OF ASTROBIOLOGY 2015; 14:401-410. [PMID: 26321880 PMCID: PMC4541537 DOI: 10.1017/s1473550414000585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 10/08/2014] [Indexed: 05/21/2023]
Abstract
Earth-like civilizations generate heat from the energy that they utilize. The thermal radiation from this heat can be a thermodynamic marker for civilizations. Here we model such planetary radiation on Earth-like planets and propose a strategy for detecting such an alien unintentional thermodynamic electromagnetic biomarker. We show that astronomical infrared (IR) civilization biomarkers may be detected within an interestingly large cosmic volume using a 70 m-class or larger telescope. In particular, the Colossus telescope with achievable coronagraphic and adaptive optics performance may reveal Earth-like civilizations from visible and IR photometry timeseries' taken during an exoplanetary orbit period. The detection of an alien heat signature will have far-ranging implications, but even a null result, given 70 m aperture sensitivity, could also have broad social implications.
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Affiliation(s)
- Jeff R. Kuhn
- University of Hawaii, Institute for Astronomy, 34 Ohia Ku St, Pukalani, Maui, HI, 96768, USA
- e-mail:
| | - Svetlana V. Berdyugina
- NASA Astrobiology Institute, University of Hawaii, Institute for Astronomy, 2680 Woodlawn Dr, Honolulu, HI 96822, USA
- Kiepenheuer Institut fuer Sonnenphysik, Schoeneckstr. 6, 79104 Freiburg, Germany
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Izidoro A, Raymond SN, Morbidelli A, Hersant F, Pierens A. GAS GIANT PLANETS AS DYNAMICAL BARRIERS TO INWARD-MIGRATING SUPER-EARTHS. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/800/2/l22] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Another super-Earth found. Nature 2014. [DOI: 10.1038/512116c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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