TY  - JOUR
AU  - Jovanović, Aleksandar
AU  - Bakić, Gordana
AU  - Golubović, Tamara
AU  - Kirin, Snežana
AU  - Sedmak, Aleksandar
PY  - 2023
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7153
AB  - The integrity assessment of high pressure steam pipeline
primarily requires stress state determination, including not
only effects of working pressure and temperature, but also
all acting loads. Toward this aim, the application of numerical methods for calculating the stress state is the best option.
Here, the integrity assessment of one of the collectors of the
RA line at Block 1 of ‘Nikola Tesla’ B Thermal Power Plant
is shown, which was the subject of reconstruction due to a
manufacturing defect in one of the welded joints. Integrity
and risk of the steam line is assessed using fracture
mechanics parameters, including microstructural analysis.
AB  - Procena integriteta parovoda pod visokim pritiskom zahteva prvenstveno utvrđivanje naponskog stanja materijala,
pri čemu treba uzeti u obzir ne samo uticaj radnog pritiska
i temperature, već i sva delujuća opterećenja. Primena neke
od numeričkih metoda proračuna za analizu naponskog
stanja je najbolji alat. Ovde je prikazana je procena integriteta jednog od kolektora RA linije na Bloku 1 Termoelektrane ’Nikola Tesla’ B koji je bio predmet rekonstrukcije
zbog greške na jednom od zavarenih spojeva. Integritet i
rizik parovoda je procenjen primenom parametra mehanike
loma, uz analizu mikrostrukture.
PB  - Society for Structural Integrity and Life (DIVK)
T2  - Structural Integrity and Life
T1  - INTEGRITY AND RISK ASSESSMENT OF RECONSTRUCTED STEAM LINE
T1  - PROCENA INTEGRITETA I RIZIKA REKONSTRUISANOG PAROVODA
EP  - 371
IS  - 3
SP  - 367
VL  - 23
UR  - https://hdl.handle.net/21.15107/rcub_technorep_7153
ER  - 

@article{
author = "Jovanović, Aleksandar and Bakić, Gordana and Golubović, Tamara and Kirin, Snežana and Sedmak, Aleksandar",
year = "2023",
abstract = "The integrity assessment of high pressure steam pipeline
primarily requires stress state determination, including not
only effects of working pressure and temperature, but also
all acting loads. Toward this aim, the application of numerical methods for calculating the stress state is the best option.
Here, the integrity assessment of one of the collectors of the
RA line at Block 1 of ‘Nikola Tesla’ B Thermal Power Plant
is shown, which was the subject of reconstruction due to a
manufacturing defect in one of the welded joints. Integrity
and risk of the steam line is assessed using fracture
mechanics parameters, including microstructural analysis., Procena integriteta parovoda pod visokim pritiskom zahteva prvenstveno utvrđivanje naponskog stanja materijala,
pri čemu treba uzeti u obzir ne samo uticaj radnog pritiska
i temperature, već i sva delujuća opterećenja. Primena neke
od numeričkih metoda proračuna za analizu naponskog
stanja je najbolji alat. Ovde je prikazana je procena integriteta jednog od kolektora RA linije na Bloku 1 Termoelektrane ’Nikola Tesla’ B koji je bio predmet rekonstrukcije
zbog greške na jednom od zavarenih spojeva. Integritet i
rizik parovoda je procenjen primenom parametra mehanike
loma, uz analizu mikrostrukture.",
publisher = "Society for Structural Integrity and Life (DIVK)",
journal = "Structural Integrity and Life",
title = "INTEGRITY AND RISK ASSESSMENT OF RECONSTRUCTED STEAM LINE, PROCENA INTEGRITETA I RIZIKA REKONSTRUISANOG PAROVODA",
pages = "371-367",
number = "3",
volume = "23",
url = "https://hdl.handle.net/21.15107/rcub_technorep_7153"
}

Jovanović, A., Bakić, G., Golubović, T., Kirin, S.,& Sedmak, A.. (2023). INTEGRITY AND RISK ASSESSMENT OF RECONSTRUCTED STEAM LINE. in Structural Integrity and Life
Society for Structural Integrity and Life (DIVK)., 23(3), 367-371.
https://hdl.handle.net/21.15107/rcub_technorep_7153

Jovanović A, Bakić G, Golubović T, Kirin S, Sedmak A. INTEGRITY AND RISK ASSESSMENT OF RECONSTRUCTED STEAM LINE. in Structural Integrity and Life. 2023;23(3):367-371.
https://hdl.handle.net/21.15107/rcub_technorep_7153 .

Jovanović, Aleksandar, Bakić, Gordana, Golubović, Tamara, Kirin, Snežana, Sedmak, Aleksandar, "INTEGRITY AND RISK ASSESSMENT OF RECONSTRUCTED STEAM LINE" in Structural Integrity and Life, 23, no. 3 (2023):367-371,
https://hdl.handle.net/21.15107/rcub_technorep_7153 .

TY  - JOUR
AU  - Sedmak, Aleksandar
AU  - Grbović, Aleksandar
AU  - Zaidi, Radzeya
AU  - Kirin, Snežana
AU  - Vitas, Nikola
AU  - Golubović, Tamara
AU  - Vučetić, Ivana
PY  - 2023
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7154
AB  - Numerical and analytical methods are applied to determine the remaining life of oil rig pipe with an axial crack.
Analytical expressions for surface cracks are used to calculate stress intensity factors for different crack geometries
and estimate the remaining life directly by using Paris law.
The same procedure is applied by using the FEM, verified
previously by experimental results. Good agreement between
analytical and numerical results is demonstrated.
AB  - Primenjene su numeričke i analitičke metode za određivanje preostalog veka cevi naftne platforme sa aksijalnom
prslinom. Analitički izrazi za površinske prsline korišćeni
su za izračunavanje faktora intenziteta napona za različite
geometrije prsline i za procenu preostalog veka korišćenjem Parisovog zakona. Isti postupak je primenjen korišćenjem MKE, prethodno verifikovan eksperimentom. Pokazano je dobro slaganje analitičkih i numeričkih rezultata.
PB  - Society for Structural Integrity and Life (DIVK)
T2  - Structural Integrity and Life
T1  - NUMERICAL, ANALYTICAL AND EXPERIMENTAL DETERMINATION OF REMAINING LIFE OF A PIPE WITH AN AXIAL CRACK
T1  - NUMERIČKO, ANALITIČKO I EKSPERIMENTALNO ODREĐIVANJE PREOSTALOG VEKA CEVI SA OSNOM PRSLINOM
EP  - 244
IS  - 3
SP  - 239
VL  - 23
UR  - https://hdl.handle.net/21.15107/rcub_technorep_7154
ER  - 

@article{
author = "Sedmak, Aleksandar and Grbović, Aleksandar and Zaidi, Radzeya and Kirin, Snežana and Vitas, Nikola and Golubović, Tamara and Vučetić, Ivana",
year = "2023",
abstract = "Numerical and analytical methods are applied to determine the remaining life of oil rig pipe with an axial crack.
Analytical expressions for surface cracks are used to calculate stress intensity factors for different crack geometries
and estimate the remaining life directly by using Paris law.
The same procedure is applied by using the FEM, verified
previously by experimental results. Good agreement between
analytical and numerical results is demonstrated., Primenjene su numeričke i analitičke metode za određivanje preostalog veka cevi naftne platforme sa aksijalnom
prslinom. Analitički izrazi za površinske prsline korišćeni
su za izračunavanje faktora intenziteta napona za različite
geometrije prsline i za procenu preostalog veka korišćenjem Parisovog zakona. Isti postupak je primenjen korišćenjem MKE, prethodno verifikovan eksperimentom. Pokazano je dobro slaganje analitičkih i numeričkih rezultata.",
publisher = "Society for Structural Integrity and Life (DIVK)",
journal = "Structural Integrity and Life",
title = "NUMERICAL, ANALYTICAL AND EXPERIMENTAL DETERMINATION OF REMAINING LIFE OF A PIPE WITH AN AXIAL CRACK, NUMERIČKO, ANALITIČKO I EKSPERIMENTALNO ODREĐIVANJE PREOSTALOG VEKA CEVI SA OSNOM PRSLINOM",
pages = "244-239",
number = "3",
volume = "23",
url = "https://hdl.handle.net/21.15107/rcub_technorep_7154"
}

Sedmak, A., Grbović, A., Zaidi, R., Kirin, S., Vitas, N., Golubović, T.,& Vučetić, I.. (2023). NUMERICAL, ANALYTICAL AND EXPERIMENTAL DETERMINATION OF REMAINING LIFE OF A PIPE WITH AN AXIAL CRACK. in Structural Integrity and Life
Society for Structural Integrity and Life (DIVK)., 23(3), 239-244.
https://hdl.handle.net/21.15107/rcub_technorep_7154

Sedmak A, Grbović A, Zaidi R, Kirin S, Vitas N, Golubović T, Vučetić I. NUMERICAL, ANALYTICAL AND EXPERIMENTAL DETERMINATION OF REMAINING LIFE OF A PIPE WITH AN AXIAL CRACK. in Structural Integrity and Life. 2023;23(3):239-244.
https://hdl.handle.net/21.15107/rcub_technorep_7154 .

Sedmak, Aleksandar, Grbović, Aleksandar, Zaidi, Radzeya, Kirin, Snežana, Vitas, Nikola, Golubović, Tamara, Vučetić, Ivana, "NUMERICAL, ANALYTICAL AND EXPERIMENTAL DETERMINATION OF REMAINING LIFE OF A PIPE WITH AN AXIAL CRACK" in Structural Integrity and Life, 23, no. 3 (2023):239-244,
https://hdl.handle.net/21.15107/rcub_technorep_7154 .

TY  - CONF
AU  - Sedmak, Aleksandar
AU  - Martić, Igor
AU  - Jeremić, Lazar
AU  - Kirin, Snežana
AU  - Golubović, Tamara
PY  - 2022
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/6430
AB  - The effect of proof over-pressure on pressure vessels structural integrity is analysed. Risk based approach is applied using Failure Analysis Diagramme to assess likelihood of failure. Special attention is paid to crack-like defects detected by NDT regular testing which are unacceptable by standards, but difficult to be repaired. It was show, using two examples, that such defects can remain if some strict conditions are fulfilled. In any case, with or without crack-like defects, it was shown that testing of pressure vessels with significant over-pressure can cause much more problems than it has benefits, because it acts more like the first step in eventual failure, than being proof to anything.
PB  - Elsevier B.V.
C3  - 23rd European Conference on Fracture, ECF 2022, Procedia Structural Integrity
T1  - Effects of Over-Loading on Pressure Vessel Integrity
EP  - 361
SP  - 356
VL  - 42
DO  - 10.1016/j.prostr.2022.12.044
ER  - 

@conference{
author = "Sedmak, Aleksandar and Martić, Igor and Jeremić, Lazar and Kirin, Snežana and Golubović, Tamara",
year = "2022",
abstract = "The effect of proof over-pressure on pressure vessels structural integrity is analysed. Risk based approach is applied using Failure Analysis Diagramme to assess likelihood of failure. Special attention is paid to crack-like defects detected by NDT regular testing which are unacceptable by standards, but difficult to be repaired. It was show, using two examples, that such defects can remain if some strict conditions are fulfilled. In any case, with or without crack-like defects, it was shown that testing of pressure vessels with significant over-pressure can cause much more problems than it has benefits, because it acts more like the first step in eventual failure, than being proof to anything.",
publisher = "Elsevier B.V.",
journal = "23rd European Conference on Fracture, ECF 2022, Procedia Structural Integrity",
title = "Effects of Over-Loading on Pressure Vessel Integrity",
pages = "361-356",
volume = "42",
doi = "10.1016/j.prostr.2022.12.044"
}

Sedmak, A., Martić, I., Jeremić, L., Kirin, S.,& Golubović, T.. (2022). Effects of Over-Loading on Pressure Vessel Integrity. in 23rd European Conference on Fracture, ECF 2022, Procedia Structural Integrity
Elsevier B.V.., 42, 356-361.
https://doi.org/10.1016/j.prostr.2022.12.044

Sedmak A, Martić I, Jeremić L, Kirin S, Golubović T. Effects of Over-Loading on Pressure Vessel Integrity. in 23rd European Conference on Fracture, ECF 2022, Procedia Structural Integrity. 2022;42:356-361.
doi:10.1016/j.prostr.2022.12.044 .

Sedmak, Aleksandar, Martić, Igor, Jeremić, Lazar, Kirin, Snežana, Golubović, Tamara, "Effects of Over-Loading on Pressure Vessel Integrity" in 23rd European Conference on Fracture, ECF 2022, Procedia Structural Integrity, 42 (2022):356-361,
https://doi.org/10.1016/j.prostr.2022.12.044 . .

TY  - JOUR
AU  - Kirin, Snežana
AU  - Jeremić, Lazar
AU  - Sedmak, Aleksandar
AU  - Martić, Igor
AU  - Sedmak, Simon
AU  - Vucetić, Ivana
AU  - Golubović, Tamara
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4383
AB  - Risk based analysis of reverse hydro power plant penstock structural integrity is performed using fracture mechanics parameters. To assess its structural integrity, extensive testing of the full-scale prototype had been performed, including hydrostatic over-pressurizing, during the design phase. More recently, the Failure Assessment Diagram has been used to evaluate probability, whereas phenomenological analysis has been used to estimate consequence, in the scope of common risk estimation. It is shown that over-pressuring has potential detrimental effect on pipeline safety, i.e. structural integrity.
PB  - Gruppo Italiano Frattura, Cassino
T2  - Frattura Ed Integrita Strutturale
T1  - Risk based analysis of RHPP penstock structural integrity
EP  - 352
IS  - 53
SP  - 345
DO  - 10.3221/IGF-ESIS.53.27
ER  - 

@article{
author = "Kirin, Snežana and Jeremić, Lazar and Sedmak, Aleksandar and Martić, Igor and Sedmak, Simon and Vucetić, Ivana and Golubović, Tamara",
year = "2020",
abstract = "Risk based analysis of reverse hydro power plant penstock structural integrity is performed using fracture mechanics parameters. To assess its structural integrity, extensive testing of the full-scale prototype had been performed, including hydrostatic over-pressurizing, during the design phase. More recently, the Failure Assessment Diagram has been used to evaluate probability, whereas phenomenological analysis has been used to estimate consequence, in the scope of common risk estimation. It is shown that over-pressuring has potential detrimental effect on pipeline safety, i.e. structural integrity.",
publisher = "Gruppo Italiano Frattura, Cassino",
journal = "Frattura Ed Integrita Strutturale",
title = "Risk based analysis of RHPP penstock structural integrity",
pages = "352-345",
number = "53",
doi = "10.3221/IGF-ESIS.53.27"
}

Kirin, S., Jeremić, L., Sedmak, A., Martić, I., Sedmak, S., Vucetić, I.,& Golubović, T.. (2020). Risk based analysis of RHPP penstock structural integrity. in Frattura Ed Integrita Strutturale
Gruppo Italiano Frattura, Cassino.(53), 345-352.
https://doi.org/10.3221/IGF-ESIS.53.27

Kirin S, Jeremić L, Sedmak A, Martić I, Sedmak S, Vucetić I, Golubović T. Risk based analysis of RHPP penstock structural integrity. in Frattura Ed Integrita Strutturale. 2020;(53):345-352.
doi:10.3221/IGF-ESIS.53.27 .

Kirin, Snežana, Jeremić, Lazar, Sedmak, Aleksandar, Martić, Igor, Sedmak, Simon, Vucetić, Ivana, Golubović, Tamara, "Risk based analysis of RHPP penstock structural integrity" in Frattura Ed Integrita Strutturale, no. 53 (2020):345-352,
https://doi.org/10.3221/IGF-ESIS.53.27 . .

TY  - JOUR
AU  - Đurđević, Andrijana
AU  - Zivojinović, Danijela
AU  - Grbović, Aleksandar
AU  - Sedmak, Aleksandar
AU  - Rakin, Marko
AU  - Dascau, Horia
AU  - Kirin, Snežana
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3056
AB  - In this work, fatigue crack propagation in thin-walled aluminium alloy structure with two friction stir welded T joints has been simulated numerically. Crack propagation in stiffened part of the structure between two friction stir welded T joints is analysed by using the eXtended Finite Element Method (XFEM), including software ABAQUS, as well as MORFEO, for modelling and results display. Tensile fatigue loading is applied, with stress ratio R = 0, and maximum stress sigma(max) = 10 MPa. Material properties (Al 2024-T351, as used in aeronautical industry) in different welded joints zones are adopted from available literature data. Following results are obtained by numerical analysis: stress-strain and displacement state in the structure, position of the crack tip and value of stress intensity factor for every crack propagation step, as well as the structural life estimation, i.e. number of load cycles, N, also for each crack propagation step. Using these results the number of cycles at which the crack starts to propagate in an unstable manner is predicted.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Engineering Failure Analysis
T1  - Numerical simulation of fatigue crack propagation in friction stir welded joint made of Al 2024-T351 alloy
EP  - 484
SP  - 477
VL  - 58
DO  - 10.1016/j.engfailanal.2015.08.028
ER  - 

@article{
author = "Đurđević, Andrijana and Zivojinović, Danijela and Grbović, Aleksandar and Sedmak, Aleksandar and Rakin, Marko and Dascau, Horia and Kirin, Snežana",
year = "2015",
abstract = "In this work, fatigue crack propagation in thin-walled aluminium alloy structure with two friction stir welded T joints has been simulated numerically. Crack propagation in stiffened part of the structure between two friction stir welded T joints is analysed by using the eXtended Finite Element Method (XFEM), including software ABAQUS, as well as MORFEO, for modelling and results display. Tensile fatigue loading is applied, with stress ratio R = 0, and maximum stress sigma(max) = 10 MPa. Material properties (Al 2024-T351, as used in aeronautical industry) in different welded joints zones are adopted from available literature data. Following results are obtained by numerical analysis: stress-strain and displacement state in the structure, position of the crack tip and value of stress intensity factor for every crack propagation step, as well as the structural life estimation, i.e. number of load cycles, N, also for each crack propagation step. Using these results the number of cycles at which the crack starts to propagate in an unstable manner is predicted.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Engineering Failure Analysis",
title = "Numerical simulation of fatigue crack propagation in friction stir welded joint made of Al 2024-T351 alloy",
pages = "484-477",
volume = "58",
doi = "10.1016/j.engfailanal.2015.08.028"
}

Đurđević, A., Zivojinović, D., Grbović, A., Sedmak, A., Rakin, M., Dascau, H.,& Kirin, S.. (2015). Numerical simulation of fatigue crack propagation in friction stir welded joint made of Al 2024-T351 alloy. in Engineering Failure Analysis
Pergamon-Elsevier Science Ltd, Oxford., 58, 477-484.
https://doi.org/10.1016/j.engfailanal.2015.08.028

Đurđević A, Zivojinović D, Grbović A, Sedmak A, Rakin M, Dascau H, Kirin S. Numerical simulation of fatigue crack propagation in friction stir welded joint made of Al 2024-T351 alloy. in Engineering Failure Analysis. 2015;58:477-484.
doi:10.1016/j.engfailanal.2015.08.028 .

Đurđević, Andrijana, Zivojinović, Danijela, Grbović, Aleksandar, Sedmak, Aleksandar, Rakin, Marko, Dascau, Horia, Kirin, Snežana, "Numerical simulation of fatigue crack propagation in friction stir welded joint made of Al 2024-T351 alloy" in Engineering Failure Analysis, 58 (2015):477-484,
https://doi.org/10.1016/j.engfailanal.2015.08.028 . .

TY  - JOUR
AU  - Sedmak, Tamara
AU  - Bakić, Ramo
AU  - Sedmak, Stojan
AU  - Milović, Ljubica
AU  - Kirin, Snežana
PY  - 2012
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2051
AB  - The risk of brittle fracture of the penstock of the reversible pump turbine is recognized in an early stage of design. To reduce the cost of penstock construction one tunnel is accepted. The HSLA steel of 700 MPa yield stress, 47 mm thick, is selected for the most stressed penstock section. It was necessary to assure structural integrity of welded joints and the penstock structure by involving an appropriate maintenance and repair approach. Maintenance procedures are in continuous development, and the most promising probably is the risk-based approach, developed recently. Basic requirements of this approach are considered in the paper, and the possibility and convenience to apply them for the penstock is evaluated.
AB  - Rizik od krtog loma cevovoda reverzibilne turbine je ocenjen u ranoj fazi projektovanja. Da bi se smanjili troškovi izgradnje cevovoda prihvaćen je jedan tunel. Zbog toga je za najopterećeniji segment cevovoda izabran HSLA čelik, 700 MPa napona tečenja, debljine 47 mm. Bilo je potrebno i da se osigura integritet zavarenih spojeva i konstrukcije cevovoda uvođenjem odgovarajućeg pristupa za održavanje i opravke. Postupci održavanja se neprekidno razvijaju, a možda su najperspektivniji postupci zasnovani na riziku, razvijeni poslednjih godina. U radu su razmotreni osnovni zahtevi novih pristupa, i ocenjena je mogućnost i pogodnost njihove primene na cevovod.
PB  - Society for Structural Integrity and Life, Institute for Material Testing
T2  - Integritet i vek konstrukcija
T1  - Applicability of risk-based maintenance strategy to a penstock
T1  - Strategija održavanja zasnovana na riziku - primenljivost na cevovod
EP  - 196
IS  - 3
SP  - 191
VL  - 12
UR  - https://hdl.handle.net/21.15107/rcub_technorep_2051
ER  - 

@article{
author = "Sedmak, Tamara and Bakić, Ramo and Sedmak, Stojan and Milović, Ljubica and Kirin, Snežana",
year = "2012",
abstract = "The risk of brittle fracture of the penstock of the reversible pump turbine is recognized in an early stage of design. To reduce the cost of penstock construction one tunnel is accepted. The HSLA steel of 700 MPa yield stress, 47 mm thick, is selected for the most stressed penstock section. It was necessary to assure structural integrity of welded joints and the penstock structure by involving an appropriate maintenance and repair approach. Maintenance procedures are in continuous development, and the most promising probably is the risk-based approach, developed recently. Basic requirements of this approach are considered in the paper, and the possibility and convenience to apply them for the penstock is evaluated., Rizik od krtog loma cevovoda reverzibilne turbine je ocenjen u ranoj fazi projektovanja. Da bi se smanjili troškovi izgradnje cevovoda prihvaćen je jedan tunel. Zbog toga je za najopterećeniji segment cevovoda izabran HSLA čelik, 700 MPa napona tečenja, debljine 47 mm. Bilo je potrebno i da se osigura integritet zavarenih spojeva i konstrukcije cevovoda uvođenjem odgovarajućeg pristupa za održavanje i opravke. Postupci održavanja se neprekidno razvijaju, a možda su najperspektivniji postupci zasnovani na riziku, razvijeni poslednjih godina. U radu su razmotreni osnovni zahtevi novih pristupa, i ocenjena je mogućnost i pogodnost njihove primene na cevovod.",
publisher = "Society for Structural Integrity and Life, Institute for Material Testing",
journal = "Integritet i vek konstrukcija",
title = "Applicability of risk-based maintenance strategy to a penstock, Strategija održavanja zasnovana na riziku - primenljivost na cevovod",
pages = "196-191",
number = "3",
volume = "12",
url = "https://hdl.handle.net/21.15107/rcub_technorep_2051"
}

Sedmak, T., Bakić, R., Sedmak, S., Milović, L.,& Kirin, S.. (2012). Applicability of risk-based maintenance strategy to a penstock. in Integritet i vek konstrukcija
Society for Structural Integrity and Life, Institute for Material Testing., 12(3), 191-196.
https://hdl.handle.net/21.15107/rcub_technorep_2051

Sedmak T, Bakić R, Sedmak S, Milović L, Kirin S. Applicability of risk-based maintenance strategy to a penstock. in Integritet i vek konstrukcija. 2012;12(3):191-196.
https://hdl.handle.net/21.15107/rcub_technorep_2051 .

Sedmak, Tamara, Bakić, Ramo, Sedmak, Stojan, Milović, Ljubica, Kirin, Snežana, "Applicability of risk-based maintenance strategy to a penstock" in Integritet i vek konstrukcija, 12, no. 3 (2012):191-196,
https://hdl.handle.net/21.15107/rcub_technorep_2051 .