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Mohammed, Omar D.
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Publications (10 of 11) Show all publications
Mohammed, O. D. & Rantatalo, M. (2016). Dynamic Response and Time-Frequency Analysis for Gear Tooth Crack Detection (ed.). Paper presented at . Mechanical systems and signal processing, 66-67, 612-624
Open this publication in new window or tab >>Dynamic Response and Time-Frequency Analysis for Gear Tooth Crack Detection
2016 (English)In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 66-67, p. 612-624Article in journal (Refereed) Published
Abstract [en]

Vibration health monitoring is a non-destructive technique which can be applied to detect cracks propagating in gear teeth. This paper studies gear tooth crack detection by investigating the natural frequencies and by performing time-frequency analysis of a 6 DOF dynamic gear model. The gear mesh stiffness used in the model was calculated analytically for different cases of crack sizes. The frequency response functions (FRFs) of the model were derived for healthy and faulty cases and dynamic simulation was performed to obtain the time signal responses. A new approach involving a short-time Fourier transform (STFT) was applied where a fast Fourier transform (FFT) was calculated for successive blocks with different sizes corresponding to the time segments of the varying gear mesh stiffness. The relationship between the different crack sizes and the mesh-stiffness-dependent eigenfrequencies was studied in order to detect the tooth crack and to estimate its size.

National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-8682 (URN)10.1016/j.ymssp.2015.05.015 (DOI)000362861700041 ()2-s2.0-84946475247 (Scopus ID)7390dea9-d1ec-447d-bc09-1b4e165ff859 (Local ID)7390dea9-d1ec-447d-bc09-1b4e165ff859 (Archive number)7390dea9-d1ec-447d-bc09-1b4e165ff859 (OAI)
Note
Validerad; 2015; Nivå 2; 20150104 (omamoh)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mohammed, O. D. & Rantatalo, M. (2016). Residual Signal Techniques Used for Gear Fault Detection (ed.). In: (Ed.), Uday Kumar; Alireza Ahmadi; Ajit Kumar Verma; Prabhakar Varde (Ed.), Current Trends in Reliability, Availability, Maintainability and Safety: An Industry Perspective. Paper presented at International Conference ICRESH-ARMS 2015 : 01/06/2015 - 04/06/2015 (pp. 157-163). Encyclopedia of Global Archaeology/Springer Verlag
Open this publication in new window or tab >>Residual Signal Techniques Used for Gear Fault Detection
2016 (English)In: Current Trends in Reliability, Availability, Maintainability and Safety: An Industry Perspective / [ed] Uday Kumar; Alireza Ahmadi; Ajit Kumar Verma; Prabhakar Varde, Encyclopedia of Global Archaeology/Springer Verlag, 2016, p. 157-163Conference paper, Published paper (Refereed)
Abstract [en]

The role of vibration monitoring is to detect any impact on the vibration signal due to gear degradation and to give an early warning. Early detection allows a proper scheduled shutdown to prevent failure. Residual signal method can be applied to improve the extraction of the hidden fault impact. The current paper presents a comparative study of three different residual techniques. The paper concludes with a brief discussion on the used methods.

Place, publisher, year, edition, pages
Encyclopedia of Global Archaeology/Springer Verlag, 2016
Series
Lecture Notes in Mechanical Engineering, ISSN 2195-4356
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-37233 (URN)10.1007/978-3-319-23597-4_12 (DOI)2-s2.0-85043786303 (Scopus ID)b32fa0ec-187d-435e-b50c-b8a7df4df2c8 (Local ID)978-3-319-23596-7 (ISBN)978-3-319-23597-4 (ISBN)b32fa0ec-187d-435e-b50c-b8a7df4df2c8 (Archive number)b32fa0ec-187d-435e-b50c-b8a7df4df2c8 (OAI)
Conference
International Conference ICRESH-ARMS 2015 : 01/06/2015 - 04/06/2015
Note

Godkänd; 2016; Bibliografisk uppgift: Containing selected papers from the ICRESH-ARMS 2015 conference in Lulea, Sweden, collected by editors with years of experiences in Reliability and maintenance modeling, risk assessment, and asset management, this work maximizes reader insights into the current trends in Reliability, Availability, Maintainability and Safety (RAMS) and Risk Management. Featuring a comprehensive analysis of the significance of the role of RAMS and Risk Management in the decision making process during the various phases of design, operation, maintenance, asset management and productivity in Industrial domains, these proceedings discuss key issues and challenges in the operation, maintenance and risk management of complex engineering systems and will serve as a valuable resource for those in the field. ; 20151222 (andbra)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-03-29Bibliographically approved
Mohammed, O. D. (2015). Dynamic Modelling and Vibration Analysis for Gear Tooth Crack Detection (ed.). (Doctoral dissertation). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>Dynamic Modelling and Vibration Analysis for Gear Tooth Crack Detection
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of applying vibration-based condition monitoring in gear systems is to detect the initiation and development of degradation before the occurrence of failure. Eventually, degradation will result in a malfunction of the gearing system, which will affect the availability of the whole system. Early detection allows proper scheduled shutdown to prevent catastrophic failure and consequently results in a safer operation and higher cost reduction. The current thesis deals with crack modelling from a condition monitoring perspective and focuses on the early detection of cracks propagating in gear teeth using vibration signal analysis. The research approach is based on crack modelling and gear mesh stiffness calculation, dynamic modelling and simulation, and methods for fault detection by means of dynamic response and vibration analysis. The time-varying gear mesh stiffness has been studied for cracked gears, and different crack progression scenarios have been applied. Different gear dynamic models have been used for simulating the dynamic response of the studied gear system. The gyroscopic effect of the gear disc has been studied by introducing a 12 DOF gear dynamic model. Signal processing techniques have been used in vibration signal analysis for detecting any impact of the crack. Moreover, the changes in the system dynamic response with varying mesh stiffness have been investigated. The possibility of detecting cracks has then been studied using the changes in the dynamic response of the system due to a stiffness reduction of the cracked tooth.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2015
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-17442 (URN)368bd13e-4bc6-4624-bf43-a34791135cd7 (Local ID)978-91-7583-230-2 (ISBN)978-91-7583-231-9 (ISBN)368bd13e-4bc6-4624-bf43-a34791135cd7 (Archive number)368bd13e-4bc6-4624-bf43-a34791135cd7 (OAI)
Note
Godkänd; 2015; 20150214 (omamoh); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Omar Dawood Mohammed Ämne: Drift och underhållsteknik/Operation and Maintenance Avhandling: Dynamic Modelling and Vibration Analysis for Gear Tooth Crack Detection Opponent: Emeritus professor Robert Randall, School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, Australia Ordförande: Professor Uday Kumar, Avd för drift, underhåll och akustik, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Tisdag den 24 mars 2015, kl 10.00 Plats: C305, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Mohammed, O. D., Rantatalo, M. & Aidanpää, J.-O. (2015). Dynamic modelling of a one-stage spur gear system and vibration-based tooth crack detection analysis (ed.). Paper presented at . Mechanical systems and signal processing, 54(1), 293-305
Open this publication in new window or tab >>Dynamic modelling of a one-stage spur gear system and vibration-based tooth crack detection analysis
2015 (English)In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 54, no 1, p. 293-305Article in journal (Refereed) Published
Abstract [en]

For the purpose of simulation and vibration-based condition monitoring of a geared system, it is important to model the system with an appropriate number of degrees of freedom (DOF). In earlier papers several models were suggested and it is therefore of interest to evaluate their limitations. In the present study a 12 DOF gear dynamic model including a gyroscopic effect was developed and the equations of motions were derived. A one-stage reduction gear was modelled using three different dynamic models (with 6, 8 and 8 reduced to 6 DOF), as well as thedeveloped model (with 12 DOF), which is referred as the fourth model in this paper. The time-varying mesh stiffness was calculated, and dynamic simulation was then performed for different crack sizes. Time domain scalar indicators (the RMS, kurtosis and the crest factor) were applied for fault detection analysis. The results of the first model showa clearly visible difference from those of the other studied models, which were made more realistic by including two more DOF to describe the motor and load. Both the symmetric and the asymmetric disc cases were studied using the fourth model. In the case of disc symmetry, the results of the obtained response are close to those obtained from both the second and third models. Furthermore, the second model showed a slight influence from inter-tooth friction, andtherefore the third model is adequate for simulating the pinion’s y-displacement in the case of the symmetric disc. In the case of the asymmetric disc, the results deviate from those obtained in the symmetric case. Therefore, for simulating the pinion’s y-displacement, the fourth model can be considered for more accurate modelling in the case of the asymmetric disc.

National Category
Other Civil Engineering Other Mechanical Engineering
Research subject
Operation and Maintenance; Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-11531 (URN)10.1016/j.ymssp.2014.09.001 (DOI)000347856300020 ()2-s2.0-84915767148 (Scopus ID)a886db27-a5ab-459a-8a1f-0d55f630efe2 (Local ID)a886db27-a5ab-459a-8a1f-0d55f630efe2 (Archive number)a886db27-a5ab-459a-8a1f-0d55f630efe2 (OAI)
Note
Validerad; 2014; Nivå 2; 20140902 (omamoh)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mohammed, O. D., Rantatalo, M. & Aidanpää, J.-O. (2015). Dynamic modelling of gear system with gyroscopic effect and crack detection analysis (ed.). In: (Ed.), Paolo Pennacchi (Ed.), Proceedings of the 9th IFToMM International Conference on Rotor Dynamics: . Paper presented at IFToMM International Conference on Rotor Dynamics : 22/09/2014 - 25/09/2014 (pp. 1303-1314). : Encyclopedia of Global Archaeology/Springer Verlag, X
Open this publication in new window or tab >>Dynamic modelling of gear system with gyroscopic effect and crack detection analysis
2015 (English)In: Proceedings of the 9th IFToMM International Conference on Rotor Dynamics / [ed] Paolo Pennacchi, Encyclopedia of Global Archaeology/Springer Verlag, 2015, Vol. X, p. 1303-1314Conference paper, Published paper (Refereed)
Abstract [en]

In this paper a 12 DOF gear dynamic model was developed and the equations of motions were derived. A one-stage reduction gear was modelled with gyroscopic effect of the gear disc, and both cases of symmetric and asymmetric disc were studied. Gear mesh stiffness was calculated for different crack sizes, and dynamic response was simulated. Time domain scalar indicators (the RMS, kurtosis and the crest factor) were applied for fault detection analysis. In the case of asymmetric disc the simulation shows results that are different from those obtained in the symmetric case. The coupling terms have an effect on the obtained pinion’s displacement which is studied for fault detection analysis. Therefore, for simulating the pinion’s displacement, this model can be considered for more accurate modelling in case of asymmetric disc.

Place, publisher, year, edition, pages
Encyclopedia of Global Archaeology/Springer Verlag, 2015
Series
Mechanisms and Machine Science, ISSN 2211-0984 ; 21
National Category
Other Civil Engineering Other Mechanical Engineering
Research subject
Operation and Maintenance; Computer Aided Design
Identifiers
urn:nbn:se:ltu:diva-32690 (URN)10.1007/978-3-319-06590-8_106 (DOI)2-s2.0-84937458670 (Scopus ID)741bd8e8-64aa-4fe7-a92a-0369b279cc33 (Local ID)978-3-319-06589-2 (ISBN)978-3-319-06590-8 (ISBN)741bd8e8-64aa-4fe7-a92a-0369b279cc33 (Archive number)741bd8e8-64aa-4fe7-a92a-0369b279cc33 (OAI)
Conference
IFToMM International Conference on Rotor Dynamics : 22/09/2014 - 25/09/2014
Note
Validerad; 2015; Nivå 1; 20150106 (omamoh)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Mohammed, O. D. & Rantatalo, M. (2014). Performance of time domain indicators for gear tooth root crack detection and their noise-sensitivity (ed.). In: (Ed.), Giorgio Dalpiaz (Ed.), Advances in Condition Monitoring of Machinery in Non-Stationary Operations: Proceedings of the third International Conference on Condition Monitoring of Machinery in Non-Stationary Operations CMMNO 2013. Paper presented at International Conference on Condition Monitoring of Machinery in Non-Stationary Operations : 08/05/2013 - 10/05/2013 (pp. 303-312). Berlin: Encyclopedia of Global Archaeology/Springer Verlag, IV
Open this publication in new window or tab >>Performance of time domain indicators for gear tooth root crack detection and their noise-sensitivity
2014 (English)In: Advances in Condition Monitoring of Machinery in Non-Stationary Operations: Proceedings of the third International Conference on Condition Monitoring of Machinery in Non-Stationary Operations CMMNO 2013 / [ed] Giorgio Dalpiaz, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2014, Vol. IV, p. 303-312Conference paper, Published paper (Refereed)
Abstract [en]

There are different statistical fault detection indicators applied in the time domain to detect crack propagation in the gear tooth root. ‘TALAF’ and ‘THIKAT’ are two newly presented indicators which have been designed and rec-ommended to improve the performance of ball bearing fault detection after a cer-tain stage of degradation. This paper studies the performance of these two new in-dicators, together with the RMS, kurtosis and crest factor indicators, in the context of detecting faults in the gear tooth root. The paper also presents an investigation of the performance of these indicators in the presence of three levels of random background noise. Gear mesh stiffness calculations and dynamic simulation have been performed using Matlab™ to obtain the residual gear centre point displace-ment signals for different crack propagation cases. The simulations indicate that the RMS and kurtosis perform well for crack depths up to approximately 50% of the tooth root thickness. Kurtosis and THIKAT show the most sensitive perfor-mance with an increasing noise level.

Place, publisher, year, edition, pages
Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2014
Series
Lecture Notes in Mechanical Engineering, ISSN 2195-4356
National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-27243 (URN)10.1007/978-3-642-39348-8_25 (DOI)000334677400025 ()84951824516 (Scopus ID)09bb2f9c-4475-44ff-9698-db6e9e525b65 (Local ID)978-3-642-39347-1 (ISBN)978-3-642-39348-8 (ISBN)09bb2f9c-4475-44ff-9698-db6e9e525b65 (Archive number)09bb2f9c-4475-44ff-9698-db6e9e525b65 (OAI)
Conference
International Conference on Condition Monitoring of Machinery in Non-Stationary Operations : 08/05/2013 - 10/05/2013
Note
Godkänd; 2014; 20130624 (omamoh)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-07-10Bibliographically approved
Mohammed, O. D. & Rantatalo, M. (2013). Gear tooth crack detection using dynamic response analysis (ed.). In: (Ed.), (Ed.), 10th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2013, CM 2013 and MFPT 2013: . Paper presented at International Conference on Condition Monitoring and Machinery Failure Prevention Technologies : 18/06/2013 - 20/06/2013 (pp. 977-988). , 2
Open this publication in new window or tab >>Gear tooth crack detection using dynamic response analysis
2013 (English)In: 10th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2013, CM 2013 and MFPT 2013, 2013, Vol. 2, p. 977-988Conference paper, Published paper (Refereed)
Abstract [en]

Efficient non-destructive fault detection and severity assessment can be performed using vibration analysis. This paper studies gear tooth crack detection through investigating the natural frequencies of the studied gear model. The gear mesh stiffness was obtained analytically, and dynamic simulation was performed. Moreover, the frequency response functions (FRFs) were calculated for healthy and faulty gears. A change in the eigenfrequencies could be observed with increasing crack size, and thus the dynamic response could give an indication of gear tooth cracks.

National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-32184 (URN)6986336c-b00d-40a9-8a9e-69dfc1b42b6c (Local ID)978-1-62993-992-6 (ISBN)6986336c-b00d-40a9-8a9e-69dfc1b42b6c (Archive number)6986336c-b00d-40a9-8a9e-69dfc1b42b6c (OAI)
Conference
International Conference on Condition Monitoring and Machinery Failure Prevention Technologies : 18/06/2013 - 20/06/2013
Note
Godkänd; 2013; 20130624 (omamoh)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Mohammed, O. D. & Rantatalo, M. (2013). Gear tooth crack detection using dynamic response analysis (ed.). Paper presented at . Insight (Northampton), 55(8), 417-421
Open this publication in new window or tab >>Gear tooth crack detection using dynamic response analysis
2013 (English)In: Insight (Northampton), ISSN 1354-2575, E-ISSN 1754-4904, Vol. 55, no 8, p. 417-421Article in journal (Refereed) Published
Abstract [en]

Efficient non-destructive fault detection and severity assessment can be performed using vibration analysis. This paper studies gear tooth crack detection through investigating the natural frequencies of the studied gear model. The gear mesh stiffness was obtainedanalytically, and dynamic simulation was performed. Moreover, the frequency response functions (FRFs) were calculated for healthy and faulty gears. A change in the eigenfrequencies could be observed with increasing crack size, and thus the dynamic response could give an indication of gear tooth cracks.

National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-7427 (URN)10.1784/insi.2012.55.8.417 (DOI)000323877300005 ()2-s2.0-84882958628 (Scopus ID)5ce33403-8020-462b-8dbe-86418b5478d5 (Local ID)5ce33403-8020-462b-8dbe-86418b5478d5 (Archive number)5ce33403-8020-462b-8dbe-86418b5478d5 (OAI)
Note
Validerad; 2013; 20130819 (omamoh)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mohammed, O. D., Rantatalo, M. & Aidanpää, J.-O. (2013). Improving mesh stiffness calculation of cracked gears for the purpose of vibration-based fault analysis (ed.). Paper presented at . Engineering Failure Analysis, 34, 235-251
Open this publication in new window or tab >>Improving mesh stiffness calculation of cracked gears for the purpose of vibration-based fault analysis
2013 (English)In: Engineering Failure Analysis, ISSN 1350-6307, E-ISSN 1873-1961, Vol. 34, p. 235-251Article in journal (Refereed) Published
Abstract [en]

For the purpose of vibration-based condition monitoring and to prevent occurrence of catastrophic gear failures it is important to improve the simulated dynamic response of the studied gear model. The time varying gear mesh stiffness will contribute to the dynamic response of a geared system. Some previously applied methods for stiffness calculation, described in the literature, show good agreement with the results obtained with FEM simulation for smaller crack sizes. However, when larger crack sizes are reached, these methods show an increasing deviation from FEM simulation results. A reduction in the gear mesh stiffness can be considered to assess the status of tooth damage and, therefore, by increasing the accuracy of the calculated mesh stiffness, dynamic simulations of a gear can be improved. In this paper a new method is presented for calculating the gear mesh stiffness for a propagating crack in the tooth root. The influence of gear mesh stiffness on the vibration-based fault detection indicators, the RMS, kurtosis and the crest factor, is investigated. Different crack sizes are examined by using this new method for sizes up to around 50% of the total tooth root thickness. When compared to FEM simulations, the presented method shows more accurate results for calculations of the gear mesh stiffness (for the studied model) than the previously suggested methods.

National Category
Other Civil Engineering Applied Mechanics
Research subject
Operation and Maintenance; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-16357 (URN)10.1016/j.engfailanal.2013.08.008 (DOI)000329080800024 ()2-s2.0-84884130926 (Scopus ID)ffb8d0bb-8e2a-4f34-b49d-4ed6e576d1cd (Local ID)ffb8d0bb-8e2a-4f34-b49d-4ed6e576d1cd (Archive number)ffb8d0bb-8e2a-4f34-b49d-4ed6e576d1cd (OAI)
Note
Validerad; 2013; 20130820 (omamoh)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Mohammed, O. D., Rantatalo, M., Aidanpää, J.-O. & Kumar, U. (2013). Vibration signal analysis for gear fault diagnosis with various crack progression scenarios (ed.). Paper presented at . Mechanical systems and signal processing, 41(1-2), 176-195
Open this publication in new window or tab >>Vibration signal analysis for gear fault diagnosis with various crack progression scenarios
2013 (English)In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 41, no 1-2, p. 176-195Article in journal (Refereed) Published
Abstract [en]

There are different analytical scenarios assumed for crack propagation in the gear tooth root. This paper presents an investigation of the performance of statistical fault detection indicators (the RMS and kurtosis) for three different series of crack propagation scenarios, to compare these scenarios from a fault diagnostics point of view. These scenarios imply different forms of cracks with propagation by a certain step of crack depth. The 1st scenario assumes a crack being extended through the whole tooth width with a uniform crack depth distribution, while the 2nd scenario assumes the crack being extended through the whole tooth width with a parabolic crack depth distribution, and finally in the 3rd scenario the crack is assumed to be propagating in both the depth and the length directions simultaneously. The time-varying gear mesh stiffness has been investigated using the program code developed in the present research, and the crack propagation can be modelled with any of the presented crack propagation scenarios. Dynamic simulation has been performed to obtain the residual signals of all the studied cases for each crack propagation scenario. The comparison of the statistical indicators applied to the residual signals shows that in the 1st scenario the faults are most easily detectable, since in this scenario there is a change in the indicators implying a dramatic decrease in the gear mesh stiffness. The fault detection in the 2nd scenario is more difficult, as the crack propagates with no significant reflection on the mesh stiffness loss. The 3rd proposed scenario should receive more attention in research because it could occur in reality in case of non-uniform load distribution. However, with this scenario it is difficult to perform early fault detection, since there is a very slight change in the statistical indicators at the beginning of the crack propagation. After which, these indicators show a significant change when the crack grows deeper which implies a serious crack propagation condition.

National Category
Other Civil Engineering Applied Mechanics
Research subject
Operation and Maintenance; Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-10161 (URN)10.1016/j.ymssp.2013.06.040 (DOI)000327683600012 ()2-s2.0-84885619321 (Scopus ID)8eaec575-2932-414e-a603-aee2d13a9f9c (Local ID)8eaec575-2932-414e-a603-aee2d13a9f9c (Archive number)8eaec575-2932-414e-a603-aee2d13a9f9c (OAI)
Note
Validerad; 2013; 20130625 (omamoh)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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