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Designing and developing a free fall absolute gravity measuring system using pneumatic actuators
Dissertation (MEng)--University of Pretoria, 2017.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2018
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| _version_ | 1867613628595699712 |
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| access_status_str | Open Access |
| author2 | Theron, Nicolaas J. |
| author_browse | Theron, Nicolaas J. |
| author_facet | Theron, Nicolaas J. |
| collection | Thesis |
| dc_rights_str_mv | © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MEng)--University of Pretoria, 2017. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/66225 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:10.429Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/66225 Designing and developing a free fall absolute gravity measuring system using pneumatic actuators Theron, Nicolaas J. u29467013@tuks.co.za Greeff, Pieter Mokobodi, Dineo Stephen UCTD Absolute gravity measurement Free fall systems Pneumatic actuators Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-04 SDG-04: Quality education Engineering, built environment and information technology theses SDG-12 SDG-12: Responsible consumption and production Dissertation (MEng)--University of Pretoria, 2017. A gravimeter is an instrument that measures gravitational force Fg (N) or acceleration g (m/s-2). Absolute gravity measurements are preferred in metrology, due to the shortest traceability links to the SI base units of length and time, realising acceleration. The investigation on the suitable method of gravity measurement was performed at the National Metrology Institute of South Africa (NMISA). The free fall gravity measuring system was adopted for development. The metrological need on redefining the kilogramme standard using the watt balance, supported the decision to mandate this project. Free fall gravimeters were researched. The new concept of fully pneumatic controlled vacuum chamber was invented and manufactured. Pneumatic actuators were used on the vacuum chamber to align, launch, capture and reposition the falling test mass. Laser interferometer and high-speed digitiser with embedded accurate clock module, were used in realising displacement and time, through numerical computations. Using stabilised He-Ne Laser red with wavelength =633 nm interferometer, free-falling test mass displacements were traceable to length standard. Interference intensity signal produced from experimental free fall drops were converted to A digital voltage signal enabling processing. Post signal processing algorithms were applied to the signal to extract the displacement and time coordinates of the free-falling object, using a zero-crossing detection method in a LabView environment. The final prototype setup measured the value 9.786041 m/s2 with uncertainty of 0.0000705 m/s2 at the vacuum pressure of 0.05 Pa. It was validated and compared with the Council of Geophysics_ measured value of the site of 9.7860985 m/s2. mi2025 Mechanical and Aeronautical Engineering MEng Unrestricted SDG-09: Industry, innovation and infrastructure SDG-04: Quality education SDG-12: Responsible consumption and production 2018-08-17T09:42:43Z 2018-08-17T09:42:43Z 2005/03/18 2017 Dissertation Mokobodi, DS 2017, Designing and developing a free fall absolute gravity measuring system using pneumatic actuators, MEng Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/66225> A2018 http://hdl.handle.net/2263/66225 en © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Absolute gravity measurement Free fall systems Pneumatic actuators Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-04 SDG-04: Quality education Engineering, built environment and information technology theses SDG-12 SDG-12: Responsible consumption and production Designing and developing a free fall absolute gravity measuring system using pneumatic actuators |
| title | Designing and developing a free fall absolute gravity measuring system using pneumatic actuators |
| title_full | Designing and developing a free fall absolute gravity measuring system using pneumatic actuators |
| title_fullStr | Designing and developing a free fall absolute gravity measuring system using pneumatic actuators |
| title_full_unstemmed | Designing and developing a free fall absolute gravity measuring system using pneumatic actuators |
| title_short | Designing and developing a free fall absolute gravity measuring system using pneumatic actuators |
| title_sort | designing and developing a free fall absolute gravity measuring system using pneumatic actuators |
| topic | UCTD Absolute gravity measurement Free fall systems Pneumatic actuators Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-04 SDG-04: Quality education Engineering, built environment and information technology theses SDG-12 SDG-12: Responsible consumption and production |
| url | http://hdl.handle.net/2263/66225 |