Detail projektu

Pokročilý popis šíření trhlin v kompozitech na bázi alkalicky aktivované matrice

Období řešení: 01.01.2018 — 31.12.2020

Zdroje financování

Grantová agentura České republiky - Juniorské granty

- plně financující (2018-02-21 - 2020-12-31)

O projektu

V rámci projektu budou navrženy a testovány (semi)analytické modely (založené na konceptu více-parametrové lomové mechaniky) pro popis šíření trhliny a odhad rozsahu lomové procesní zóny v kvazikřehkém tělese zatěžovaném v kombinovaném módu namáhání, na což v dosavadním výzkumu nebyla soustředěna patřičná pozornost. Výsledky získané pomocí navržených přístupů budou porovnány s experimentálními měřeními (získanými např. za pomoci akustické emise), což by mělo ověřit platnost a použitelnost prezentované metodiky. Za tímto účelem budou vyrobena zkušební tělesa z kvazikřehkých kompozitů na bázi alkalicky aktivované matrice a sledována bude především dráha trhliny. Testovaný materiál bude zvolen jako inovační alternativa ke klasickým materiálům na bázi Portlandského cementu. V rámci projektu budou podrobně studovány jeho lomově-mechanické vlastnosti včetně experimentů založených na cyklickém zatěžování. Získané výsledky a závěry mohou přinést nové poznatky využitelné v mnoha oblastech inženýrské lomové mechaniky, stejně jako materiálových věd.

Popis anglicky
Within this project, (semi)analytical models (based on the multi-parameter fracture mechanics approach) for description of crack propagation and estimation of the fracture process zone extent in a quasi-brittle specimen subjected to mixed-mode loading will be suggested and tested, which has not been investigated properly in existing research. The results obtained via the proposed approaches will be compared to experimental measurements (obtained e.g. via acoustic emission), which should prove the validity and applicability of the methods presented. For this purpose, specimens made from quasi-brittle composites based on alkali activated matrix will be produced and mainly the crack path will be investigated. The material under study will be chosen as an innovative alternative to ordinary Portland cement based materials. Its mechanical fracture properties including the experiments based on cyclic loading will be studied in detail. The obtained results and conclusions can bring new findings usable in many fracture mechanics engineering fields as well as in material sciences.

Klíčová slova
Alkalicky aktivovaná matrice; lomová mechanika; šíření trhliny; Williamsův rozvoj; kombinovaný mód zatěžování; cyklické zatěžování; metoda akustické emise; metoda konečných prvků

Klíčová slova anglicky
alkali activated matrix, fracture mechanics, crack propagation, Williams expansion, mixed-mode, cyclic loading, acoustic emission, finite element method

Označení

18-12289Y

Originální jazyk

čeština

Řešitelé

Útvary

Ústav stavební mechaniky
- příjemce (28.03.2017 - 31.12.2020)
Ústav stavebního zkušebnictví
- spolupříjemce (01.01.2018 - 31.12.2020)

Výsledky

MALÍKOVÁ, L.; ŠIMONOVÁ, H. Multi-parameter fracture mechanics: Effect of the specimen shape. Young Scientist 2018. Košice: Technical University of Košice, Faculty of Civil Engineering, 2018. p. 1-8. ISBN: 978-80-553-2952-9.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B. Deflection of an eccentric crack under mixed-mode conditions in an SCB specimen. Construction of Optimized Energy Potential Budownictwo o zoptymalizowanym potencjale energetycznym, 2021, vol. 9, no. 2/2020, p. 79-87. ISSN: 2544-963X.
Detail

BÍLEK Jr., V.; BULEJKO, P.; KEJÍK, P.; HAJZLER, J.; MÁSILKO, J.; BEDNÁREK, J.; TKACZ, J.; KALINA, L. Potential use of blast furnace slag for filtration membranes preparation: A pilot study. In International Conference Building Materials, Products and Technologies. IOP Conference Series: Materials Science and Engineering. Bristol: IOP Publishing, 2018. p. 1-6. ISSN: 1757-8981.
Detail

ŠIMONOVÁ, H.; LIPOWCZAN, M.; LEHKÝ, D.; KUCHARCZYKOVÁ, B.; KERŠNER, Z. Identification of mechanical fracture parameters for estimation of statistical properties of geopolymer mortars. 16th International Probabilistic Workshop. Beton- und Stahlbetonbau. Berlin: Wilhelm Ernst & Sohn, 2018. p. 1-5. ISSN: 1437-1006.
Detail

ŠIMONOVÁ, H.; DRAGAS, J.; KUCHARCZYKOVÁ, B.; KERŠNER, Z.; IGNJATOVIC, I.; KOMLJENOVIC, M.; NIKOLIC, V. Fracture Behaviour of Geopolymer Mortars Reinforced with Hemp Fibres. Proceedings for the 2018 fib Congress held in Melbourne. Switzerland: Fédération internationale du béton (fib), 2018. p. 714-715. ISBN: 978-1-877040-14-6.
Detail

TOPOLÁŘ, L.; ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B. ACOUSTIC EMISSION PARAMETERS OF ALKALI ACTIVATED FLY ASH SPECIMENS WITH HEMP FIBRES UNDER STATIC LOADING. SynerCrete’18: Interdisciplinary Approaches for Cement-based Materials and Structural Concrete: Synergizing Expertise and Bridging Scales of Space and Time. FRANCE: RILEM publications S.A.R.L., 2018. p. 383-388. ISBN: 978-2-35158-202-2.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; TOPOLÁŘ, L.; KERŠNER, Z.; MERTA, I.; DRAGAS, J.; IGNJATOVIC, I.; KOMLJENOVIC, M.; NIKOLIC, V. Crack initiation of selected geopolymer mortar with hemp fibres. Book of abstracts of 22nd European Conference on Fracture. Beograd: Society for Structural Integrity and Life, 2018. p. 151-151. ISBN: 978-86-900696-0-9.
Detail

ŠIMONOVÁ, H.; TOPOLÁŘ, L.; KUCHARCZYKOVÁ, B.; KERŠNER, Z.; DRAGAS, J.; IGNJATOVIC, I.; KOMLJENOVIC, M.; NIKOLIC, V. Comparison of different alkali activated mortars with hemp fibres response during fracture test by acoustic emission method. The 9th International Conference on Multiscale Material Modeling Abstrakt Book. Osaka: 2018. p. 310-310.
Detail

ALEXA, M.; KUCHARCZYKOVÁ, B.; KOCÁB, D.; BÍLEK, V.; HALAMOVÁ, R. Experimentální stanovení raného smrštění alkalicky aktivované strusky. 25. Betonářské dny 2018 Sborník příspěvků konference. Praha: Česká betonářská společnost ČSSI, 2018. s. 1-7. ISBN: 978-80-906759-6-4.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; TOPOLÁŘ, L.; KERŠNER, Z.; MERTA, I.; DRAGAS, J.; IGNJATOVIC, I.; KOMLJENOVIC, M.; NIKOLIC, V. Crack initiation of selected geopolymer mortar with hemp fibres. In ECF22 − Loading and Environmental effects on Structural Integrity. Procedia Structural Integrity. Elsevier, 2018. p. 578-583. ISSN: 2452-3216.
Detail

MALÍKOVÁ, L.; ŠIMONOVÁ, H. Crack Propagation in Various Double Cantilever Beam Geometric Configurations. In Proceedings of the 7th International Conference on Fracture Fatigue and Wear. FFW 2018. Lecture Notes in Mechanical Engineering. Singapore: Springer, 2018. p. 164-170. ISBN: 9789811304118. ISSN: 2195-4364.
Detail

MALÍKOVÁ, L.; ŠIMONOVÁ, H. Generalized maximum tangential stress criterion in double cantilever beam specimens: choice of the proper critical distance. In Research and Modelling in Civil Engineering 2018. 1. Koszalin: Koszalin University of Technology Publishing House, 2019. p. 199-212. ISBN: 978-83-7365-502-7.
Detail

KLON, J.; SOBEK, J. Comparison of Fracture Tests Numerical Models Created with Real Material Properties. In Advances in Fractue and Damage Mechanics XVII. Key Engineering Materials (web). 2018. p. 601-606. ISSN: 1662-9795.
Detail

SOBEK, J.; KLON, J.; TRČKA, T.; CIFUENTES, H.; RIOS JIMENEZ, J. Study on the differences between surface fracture areas for different sizes of modCT specimens. 3rd International Conference on Engineering Sciences and Technologies (ESaT 2018). Tatranské Matliare, Slovak Republic: 2018. p. 1-4. ISBN: 978-80-553-2982-6.
Detail

MALÍKOVÁ, L.; RAVAZI, S.; BERTO, F. Crack propagation in a brittle DCB specimen assessed by means of the Williams’ power expansion. Frattura ed Integrita Strutturale, 2019, vol. 13, no. 48, p. 34-41. ISSN: 1971-8993.
Detail

MALÍKOVÁ, L.; RAVAZI, S.; BERTO, F. Crack propagating in a brittle DCB specimen described by using the Williams’ power expansion. 6th International Conference on Crack Paths. Gruppo Italiano Frattura. Verona, Itálie: 2018. p. 317-322. ISSN: 2532-2443.
Detail

MIARKA, P.; SEITL, S.; DE CORTE, W. Notch Tip Displacements of the Concrete Brazilian Disc Test with Central Notch Analysed by the Concrete Damaged Plasticity Model. Theoretical and Applied Fracture Mechanics, 2019, vol. 102, no. 1, p. 122-150. ISSN: 0167-8442.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; LIPOWCZAN, M.; LEHKÝ, D.; BÍLEK, V.; KOCÁB, D. Identification of Mechanical Fracture Parameters of Alkali-Activated Slag Based Composites During Specimens Ageing. Proceedings of extended abstracts “Modelling in Mechanics 2019”. Ostrava: VŠB-TU Ostrava, Faculty of Civil Engineering, 2019. p. 30-30. ISBN: 978-80-248-4296-7.
Detail

ŠIMONOVÁ, H.; POLETANOVIC, B.; MERTA, I. Fracture parameters of alkali-activated matrix based composites. Book of abstracts of Vienna young Scientists Symposium 2019. Austria: Book-of-Abstracts.com, 2019. p. 188-189. ISBN: 978-3-9504017-9-0.
Detail

ALEXA, M.; KOCÁB, D.; KUCHARCZYKOVÁ, B.; KOTRLA, J. Experimental Determination of Early Shrinkage of Alkali-Activated Slag. In Solid State Phenomena: 25th Concrete Days 2018. Solid State Phenomena. Switzerland: Trans Tech Publications, 2019. p. 114-119. ISBN: 978-3-0357-1459-3. ISSN: 1662-9779.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; KERŠNER, Z.; MERTA, I.; POLETANOVIC, B.; MALÍKOVÁ, L.; SEITL, S. Effect of softening function type in double-K fracture model: Alkali-activated fly ash mortar with hemp fibres. France: IA-FraMCoS, 2019. p. 1-8.
Detail

MALÍKOVÁ, L.; ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; MIARKA, P. Multi-parameter fracture mechanics: crack path in a mixed-mode specimen. Frattura ed Integrita Strutturale, 2019, vol. 13, no. 49, p. 65-73. ISSN: 1971-8993.
Detail

SOBEK, J.; KLON, J.; TRČKA, T.; CIFUENTES, H.; RIOS JIMENEZ, J. Study on ligaments’ areas differences between different sizes of modCT concrete specimens. In 3rd International Conference on Engineering Sciences and Technologies, ESaT 2018; Vysoké Tatry; Slovakia; 12 September 2018 through 14 September 2018. CRC Press/Balkema, 2019. p. 235-240. ISBN: 9780367075095.
Detail

BÍLEK, V.; KALINA, L.; ŠIMONOVÁ, H. Effect of curing environment on length changes of alkali-activated slag/cement kiln by-pass dust mixtures. In International Conference Building Materials, Products and Technologies. IOP Conference Series: Materials Science and Engineering. IOP Publishing, 2019. p. 1-6. ISSN: 1757-8981.
Detail

MIARKA, P.; SEITL, S.; SUCHARDA, O.; BÍLEK, V. Fracture Resistance of Alkali Activated Concrete under the Mixed Mode I/II Load Conditions. In 3rd International Conference on Structural Integrity, ICSI 2019, 2-5 September 2019, Funchal, Madeira, Portugal. Procedia Structural Integrity. online: Elsevier, 2019. p. 610-617. ISSN: 2452-3216.
Detail

MIARKA, P.; PAN, L.; BÍLEK, V.; CIFUENTES, H.; SEITL, S. FRACTURE BEHAVIOUR OF ALKALI ACTIVATED CONCRETE MEASUREDFROM THREE-POINT BENDING TEST WITH CHEVRON NOTCH. France: IA-FraMCoS, 2019. p. 1-8.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; BÍLEK, V.; TOPOLÁŘ, L.; KOCÁB, D. Influence of curing conditions on mechanical and fracture properties of alkali activated slag concrete. Book of Abstracts of 4th International Conference Innovative Materials, Structures and Technologies. Riga: RTU Press, Riga Technical University, 2019. p. 23-24. ISBN: 978-9934-22-356-3.
Detail

KUCHARCZYKOVÁ, B.; BÍLEK, V.; ŠIMONOVÁ, H. Shrinkage of the alkali-activated slag mortars containing alternative activator. Book of Abstracts of 4th International Conference Innovative Materials, Structures and Technologies. Riga: RTU Press, Riga Technical University, 2019. p. 21-21. ISBN: 978-9934-22-356-3.
Detail

ŠIMONOVÁ, H.; DRAGAS, J.; KUCHARCZYKOVÁ, B.; KERŠNER, Z.; IGNJATOVIC, I.; KOMLJENOVIC, M.; NIKOLIC, V. Fracture Behaviour of Geopolymer Mortars Reinforced with Hemp Fibres. In FIB 2018 - Proceedings for the 2018 fib Congress: Better, Smarter, Stronger. International fib Congress on Better, Smarter, Stronger, 2018. Switzerland: Fédération internationale du béton (fib), 2019. p. 3627-3637. ISBN: 978-1-877040-15-3. ISSN: 2617-4820.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H. Crack propagation in mixed-mode specimens described via multi-parameter fracture mechanics. In The 2nd International Conference on Material Strength and Applied Mechanics, 27–30 May 2019, Kiev, Ukraine. IOP Conference Series: Materials Science and Engineering. Bristol: IOP Publishing, 2019. p. 1-5. ISSN: 1757-899X.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; BÍLEK, V.; KOCÁB, D. Mechanical fracture characterization of alkali-activated slag mortars with standardized and natural sand. SPACE 2019. Košice: Technická univerzita v Košiciach, 2019. p. 1 (1 s.). ISBN: 978-80-553-3413-4.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H. Propagation conditions of an eccentric crack in a semi-circular disk loaded in I+II mixed mode. SPACE 2019. Košice: Technická univerzita v Košiciach, 2019. p. 1 (1 s.). ISBN: 978-80-553-3413-4.
Detail

BÍLEK Jr., V.; KALINA, L.; NOVOTNÝ, R.; MÁSILKO, J.; ŠOUKAL, F. Effect of Cement Kiln Bypass Dust on Properties and Hydration of Akali-Activated Slag Mixtures. PAPERS AND POSTERS PROCEEDINGS: 15th International Congress on the Chemistry of Cement. 5th International Congress on the Chemistry of Cement (ICCC 2019) Congress proceedings – Papers and Posters Proceedings. Prague: Research Institute of Binding Materials Prague, 2019. p. – (– p.)ISSN: 2523-935X.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; LIPOWCZAN, M.; LEHKÝ, D.; BÍLEK, V.; KOCÁB, D. Identification of Mechanical Fracture Parameters of Alkali-activated Slag Based Composites During Specimens Ageing. Sborník vědeckých prací Vysoké školy báňské – Technické univerzity Ostrava, 2019, vol. 19, no. 2, p. 59-64. ISSN: 1213-1962.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; BÍLEK, V.; TOPOLÁŘ, L.; KOCÁB, D. Influence of curing conditions on mechanical and fracture properties of alkali activated slag concrete. In Proceedings of 4th International Conference on Innovative Materials, Structures and Technologies (IMST 2019). IOP Conference Series: Materials Science and Engineering. Bristol: IOP Publishing Ltd., 2019. p. 1-8. ISSN: 1757-899X.
Detail

KUCHARCZYKOVÁ, B.; BÍLEK, V.; ŠIMONOVÁ, H. Shrinkage of the alkali-activated slag mortars containing alternative activator. In Proceedings of the 4th International Conference on Innovative Materials, Structures and Technologies (IMST 2019). IOP Conference Series: Materials Science and Engineering. Bristol: IOP Publishing Ltd., 2019. p. 1-7. ISSN: 1757-899X.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H. Utilization of Williams‘ power series for etimation of crack behavior under mixed-mode loading. In Advances in Fracture and Damage Mechanics XVIII. Key Engineering Materials (print). Switzerland: Trans Tech Publications Ltd., 2020. p. 203-208. ISBN: 978-3-0357-1586-6. ISSN: 1013-9826.
Detail

MALÍKOVÁ, L.; VAVRO, L.; VAVRO, M.; KERŠNER, Z. Evaluation of fracture response of Silesian granite specimens via Effective Crack Model Approach and finite element analysis. In 9th International Conference on Materials STructure and Micromechanics of Fracture. Procedia Structural Integrity. Brno, Česká republika: Elsevier, 2020. p. 487-492. ISSN: 2452-3216.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; BÍLEK, V., Jr.; KOCÁB, D. Mechanical fracture characterization of alkali-activated slag mortars with standardized and natural sand. In SPACE 2019. MATEC Web of Conferences. France: EDP Sciences, 2020. p. 1-9. ISSN: 2261-236X.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H. Propagation conditions of an eccentric crack in a semi-circular disk loaded in I+II mixed mode. In SPACE 2019. MATEC Web of Conferences. France: EDP Sciences, 2020. p. 1-0. ISSN: 2261-236X.
Detail

MIARKA, P.; CRUCES, A.; SEITL, S.; MALÍKOVÁ, L.; LOPÉZ-CRESPO, P. Evaluation of the SIF and T-stress values of the Brazilian disc with a central notch by hybrid method. INTERNATIONAL JOURNAL OF FATIGUE, 2020, vol. 135, no. 1, p. 1-12. ISSN: 0142-1123.
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MALÍKOVÁ, J.; MIARKA, P.; ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B. Numerical analysis of a semi-circular disc with an angled crack loaded in mixed-mode. In Research and Modelling in Civil Engineering 2019. Koszalin: Koszalin University of Technology Publishing House, 2020. p. 71-84. ISBN: 978-83-7365-525-6.
Detail

MIARKA, P.; PAN, L.; BÍLEK, V.; SEITL, S.; CIFUENTES, H. Influence of the chevron notch type on the values of fracture energy evaluated on alkali-activated concrete. Engineering Fracture Mechanics, 2020, vol. 236, no. 1, p. 1-18. ISSN: 0013-7944.
Detail

LIPOWCZAN, M.; LEHKÝ, D.; ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B. Experimental and numerical analysis of the fracture response of alkali-activated slag-based materials. MATEC Web of Conferences, AMCM 2020. MATEC Web of Conferences. France: EDP Sciences, 2020. p. 1-10. ISSN: 2261-236X.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H. Crack deflection under mixed-mode loading investigated via generalized MTS criterion. In FRACTURE AND DAMAGE MECHANICS: Theory, Simulation and Experiment. AIP conference proceedings. Melville, NY: AIP Publishing, 2020. p. 1-8. ISSN: 0094-243X.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; BÍLEK, V. Lomová houževnatost malty na bázi alkalicky aktivované strusky. Sborník ke konferenci 27. Betonářské dny. Praha: Česká betonářská společnost ČSSI, 2020. s. 490-495. ISBN: 978-80-907611-3-1.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H. Mixed-mode crack propagation in a semi-circular disc under bending made of an environmental-friendly concrete. In 1st Virtual European Conference on Fracture - VECF1. Procedia Structural Integrity. Italy: Elsevier, 2020. p. 403-410. ISSN: 2452-3216.
Detail

TOPOLÁŘ, L. Pilot study of linear localization using the acoustic emission method during a semi-circular bending test. In Experimental Stress Analysis - 58th International Scientific Conference, EAN 2020. 1. Ostrava: Czech Society for Mechanics, 2020. p. 540-546. ISBN: 978-80-248-4451-0.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; BÍLEK, V.; MALÍKOVÁ, L.; MIARKA, P.; LIPOWCZAN, M. Mechanical Fracture and Fatigue Characteristics of Fine-Grained Composite Based on Sodium Hydroxide-Activated Slag Cured under High Relative Humidity. Applied Sciences - Basel, 2021, vol. 11, no. 1, p. 1-20. ISSN: 2076-3417.
Detail

MALÍKOVÁ, L.; MIARKA, P.; ŠIMONOVÁ, H. Multi-parameter MTS and SED criterion applied on a crack in an alkali-activated concrete specimen under mixed-mode loading. In Proceedings of 26th International Conference Engineering Mechanics 2020. Brno: Brno University of Technology, 2021. p. 338-341. ISBN: 978-80-214-5896-3.
Detail

MALÍKOVÁ, L.; MIARKA, P.; KUCHARCZYKOVÁ, B.; ŠIMONOVÁ, H. Williams expansion utilized for assessment of crack behaviour under mixed-mode loading in alkali-activated fine-grained composite. Fatigue and Fracture of Engineering Materials and Structures, 2021, vol. 44, no. 5, p. 1151-1161. ISSN: 1460-2695.
Detail

ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; BÍLEK, V.; KOCÁB, D. Alkali-activated Slag Mortar Containing Alternative Activator: Long-Term Mechanical Fracture Parameters. Sborník vědeckých prací Vysoké školy báňské – Technické univerzity Ostrava, 2020, vol. 2020, no. 2, p. 28-35. ISSN: 1213-1962.
Detail

KLON, J. VÝZNAM LOMOVÉ PROCESNÍ ZÓNY PŘI KVAZIKŘEHKÉM LOMU. Juniorstav 2019. Brno: 2019. s. 240-245. ISBN: 978-80-86433-71-4.
Detail

BÍLEK, V.; BÍLEK, V.; KALINA, L.; KHESTL, F.; PALOVČÍK, J.; ŠIMONOVÁ, H. Durability of alkali-activated concretes containing cement kiln by-pass dust. In International Conference Building Materials, Products and Technologies. IOP Conference Series: Materials Science and Engineering. IOP Publishing, 2021. p. 1-8. ISSN: 1757-8981.
Detail

BÍLEK, V.; ŠIMONOVÁ, H.; KUCHARCZYKOVÁ, B.; KOCÁB, D.; KERŠNER, Z. Fracture parameters of fine-grained composites based on the alkali-activated slag. In International Conference Building Materials, Products and Technologies. IOP Conference Series: Materials Science and Engineering. Bristol: IOP Publishing, 2018. p. 1-7. ISSN: 1757-8981.
Detail