Dr Spencer Onuh | University of Maiduguri (original) (raw)

Papers by Dr Spencer Onuh

Proceedings of SPIE, Oct 1, 2001

Many companies are faced with quality improvement issues on a daily basis but their response to t... more Many companies are faced with quality improvement issues on a daily basis but their response to this problem varies. This paper discusses the improvement in the defect reporting system at a medium sized manufacturing company following the appointment of an experienced, motivated, design engineer to be dedicated to that task. It sets out the situation that the engineer inherited and details the changes that were incorporated; it assesses which were successful and which failed. Following a survey of current literature, it was seen that there is little written specifically on the subject of audited defect reporting. It is felt that this study goes some way to filling that void. A successful survey of engineering companies in Southern Hampshire reinforces the principle findings, that the emphasising of the Check part of Demming's Plan-Do-Check-Act cycle is a novel approach to the Quality Improvement Process, and that it has reduced the cost of rework by an audited 80% in a period of two years.

Proceedings of SPIE, Oct 1, 2001

The business enterprise has never been in greater need of Agility and the current trend will cont... more The business enterprise has never been in greater need of Agility and the current trend will continue unabated well into the future. It is now recognized that information system is both the foundation and a necessary condition for increased responsiveness. A successful implementation of Enterprise Resource Planning (ERP) can help a company to move towards delivering on its competitive objectives as it enables suppliers to reach out to customers beyond the borders of traditional market defined by geography. The cost of implementation, even when it is successful, could be significant. Bearing in mind the potential strategic benefits, it is important that the implementation project is managed effectively. To this end a project cost model against which to benchmark ongoing project expenditure versus activities completed has been proposed in this paper.

Arid Zone Journal of Engineering, Technology and Environment, 2019

Rural to urban migration still persists in Nigeria despite government’s claim of rural developmen... more Rural to urban migration still persists in Nigeria despite government’s claim of rural development programs. This situation if not checked portends negative signal for the already over-populated urban areas, particularly in areas of food security, sanitation, housing, crimes, etc. The development of rural areas is measured by the availability of infrastructures and economic opportunities that are available to the people. These infrastructures include: transportation infrastructure, educational infrastructure, healthcare infrastructure, energy infrastructure, water supply/sanitation infrastructure, information and communication technology (ICT) infrastructure and so on. Rural areas in Nigeria urgently require accelerated infrastructure development to alleviate poverty. When this is done rapid growth is ensured and poverty is drastically reduced. The world today has become increasingly reliant on information and communication technologies (ICT) and with it comes the need for societies...

In this research work, a structural optimization methodology is applied to generate a Frame model... more In this research work, a structural optimization methodology is applied to generate a Frame model that meets CubeSat Design Standards. The frame is further subjected to software simulation that encapsulates worst case launch scenarios. The validity of the frame design has been demonstrated by quasi-static and modal analyses, with the results being verified analytically using direct stiffness approach. All subsystems in this study were modelled as remote masses at their Centre of Gravity (C.G) positions, considering their Moments of Inertia (M.I). The mass location analysis was done for a presumed internal configuration with the subsystems arranged such that the Centre of Gravity (C.G) and Moment of Inertia (M.I) values satisfy the launch vehicle constraints. The mass of the proposed structure has been reviewed to meet design mass requirements of a picosatellite structure as a subsystem with a mass less than 20 per cent of overall design mass of 1.33kg. The frame is modelled to bear ...

Strength of Materials, 2015

The approach provides simulation of the gear design with high-precision profile configuration par... more The approach provides simulation of the gear design with high-precision profile configuration parameters to accurately predict its load capacity and stress state, which requires incessant efforts, as gear failure modes depend largely on its profile representation. The finite element analysis (FEA) is a well-known effective computational method, which many authors used to estimate the gear tooth strength against the primary failure modes of gears. This method is not only known to be time-consuming but often expensive, it employs approximate geometry that resulted in a coarse mesh. The tooth strength and deformation modes were obtained from a three-dimensional gear model based on the trivariate nonuniform rational B-splines (NURBS) under loading and investigated using the isogeometric analysis (IGA) for simulation. The results produced with the IGA simulation are compared with the corresponding values derived from the classical estimation method with the Lewis equation and FEM analysis using ANSYS. Both results are in good agreement and confirm that the IGA model is more accurate than the FEM one. This study demonstrated that IGA was practically applicable, providing an alternative means of using high-precision geometry of 3D models to estimate the behavior of gear bodies under loading and modify their strength calculations.

A detailed study of the effects of layer thickness, hatch spacing, hatch overcure depth, and hatc... more A detailed study of the effects of layer thickness, hatch spacing, hatch overcure depth, and hatch fill cure depth on the quality of the StereoLithography (SL) product was carried out using acrylic based resin. Taguchi Method was used for analysing all experimental results. The ANOVA and the Signal-to-noise ratio (SIN) results were used to select the optimum parameters and the appropriate factor levels for further experiments. A new hatch styIe with an optimum layer thickness is proposed for the build process with minimum geometrical distortion.

Polymer Testing, 2006

The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties o... more The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties of layered silicate nanoclay reinforced unsaturated polyester (UPE) nanocomposites were investigated by a nano-indentation test method. The clay was dispersed into a UPE matrix via blending using a mechanical stirrer. Structural studies were carried out using a wide angle X-ray diffraction (WAXD) method and correlated with the

This paper describes a flexible modular design approach applied to the design of a sealed lead ac... more This paper describes a flexible modular design approach applied to the design of a sealed lead acid vehicle battery charger. The design process is separated into sub-processes and the design is then checked against available modules and knowledge. Potentially useful modules are then identified and used if possible. Other new modules are then created to complete the design. New products can be created from available modules if possible and this simplifies the design process and makes the process cheaper.

2010 International Conference on Education and Management Technology, 2010

Lean Production is a time tested and trusted world class production system which does more and ac... more Lean Production is a time tested and trusted world class production system which does more and achieve more with less resources by eliminating waste and ensuring continuous improvement within its value stream. Understandably, it has today become the cynosure of all eyes and center of most scholarly discuss from all fields of human endeavor due to its acclaimed success. But its continuous mill of success seems to be slowing down and dwindling by the day due to the relegation almost to extinction of the intellectually unique Human Resource which is at the heart of the Lean philosophy. It is therefore expedient that the foundation principles and pillars of all lean practicing system especially its Human Resource foundation be fortified. This paper takes an in-depth look into the Human aspects in today's Lean practice.

Journal of Medical Engineering & Technology, 2009

Research into fabrication of hip joint replacements combines knowledge from distinct domains, suc... more Research into fabrication of hip joint replacements combines knowledge from distinct domains, such as engineering, materials and medical fields. Recent computer assisted technologies have played an important role in the medical field. Unlike the modelling of most of the human bones, the creation of an accurate 3D model of a pelvic bone has been a challenging task. The main source of difficulties in this case has proven to be the complexity of the structure of the pelvis, having basically a free-form shape with a hole in the middle constituting some over-shadowed areas (undercuts), various cavities, areas with high form curvature, variable wall thickness with some very thin sections and inside layers with different mechanical properties. In this research work, a pelvic bone is generated using reverse engineering, rapid prototyping and rapid tooling techniques. The geometric data obtained from reverse engineering through laser scanning are used and manipulated to create accurate 3D CAD representations of these devices. These CAD models can be used for various virtual tests and simulations, as well as for reproduction through rapid manufacturing processes and then used as prototypes in tooling, physical tests and planning of surgical operations.

New methods are presented for controlling, programming and automating advanced production machine... more New methods are presented for controlling, programming and automating advanced production machines. Object Oriented Programming is used to model Task Machines. A brief review is provided of machine, communication and machine programming classifications. Task Machines are created from Functional Machines and some benefits of using this method are described through a comparison with conventional Imperative and Functional Programming methods. Using the new methods can improve efficiency and flexibility of machine programming systems.

Polymer Testing, 2006

The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties o... more The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties of layered silicate nanoclay reinforced unsaturated polyester (UPE) nanocomposites were investigated by a nano-indentation test method. The clay was dispersed into a UPE matrix via blending using a mechanical stirrer. Structural studies were carried out using a wide angle X-ray diffraction (WAXD) method and correlated with the nanoindentation results. This shows that nanoindentation behaviour is strongly influenced by clay reinforcement and the degree of clay dispersion in the polymer matrix. The experimental results show that there is a strong correlation between nanomechanical properties and inter layer d-spacing of clay particles in the nanocomposite system. Incorporation of 1%, 3% and 5% by weight nanoclay into the polyester resin results in an improvement in hardness of 29%, 24% and 14%, respectively. The elastic modulus increased from 5393 MPa for unreinforced polyester to 6646 MPa (23% increase) with the introduction of 5% by weight nanoclay.

Proceedings of the World Congress on Engineering, 2010

Journal of Materials Processing Technology, 2003

Abstract An experimental investigation is made on the effects of die reduction in area, die angle... more Abstract An experimental investigation is made on the effects of die reduction in area, die angle, loading rate on the quality of the extrusion products, extrusion pressures and flow pattern of cold extruded aluminium and lead alloys shapes of inner circular sections with four symmetrical projections. The radii of curvature for both extruded lead and aluminium alloys and the average hardness values of the extruded products along the projections and along the circumferential solid positions are found to increase with increase in die reduction in area, and slightly with increase of the loading rates. It shows that the non-dimensionalised values of the specific coring pressures, Pc/ϕ, and maximum extrusion pressures, Pmax/ϕ, depend primarily on the die angle, loading rate and total reduction in area of the cross-section of the complex-shaped section. These are found to be minimum at a die angle of 90°, which is recommended for die design so as to minimise extrusion pressure and hence increase die life. Empirical formulae, relating the specific maximum extrusion pressure and coring pressure to the reduction in area, R, can be expressed in the form P/ϕ=a+b ln (1/(1−R)) , where a and b are constants for a given material. Similarly, empirical formulae of the form P/ϕ=a′+b′ ln (V) are used to express the extrusion pressures (maximum or coring) P/ϕ, to the extrusion speed. Extrusion defects and the flow patterns of the extruded complex-shaped section are highlighted and discussed.

Composites Part B: Engineering, 2012

The aim of this work was to study the structure and mechanical properties of spent polyamide-12 a... more The aim of this work was to study the structure and mechanical properties of spent polyamide-12 and spent polyamide-12/layered silicate reinforced novel nanocomposites. Layered silicate at 1, 3, 5 and 7 wt.% was incorporated in spent polyamide-12 and its nanocomposites were prepared using single screw injection moulding technique. The interlamellar structure and surface morphology were characterised by transmission electron microscope (TEM) and scanning electron microscope (SEM). Different levels of layered silicate dispersion (as characterised by TEM and SEM) correlated strongly with improvements in mechanical performance. The results showed that the tensile and flexural properties are found to be increased with the incorporation of layered silicate into spent PA-12 matrix. Comparison of tensile and flexural test results between virgin PA-12, spent PA-12 and spent PA-12 nanocomposites showed that spent PA-12 samples have retained 70% of its tensile and 80% of its flexural properties respectively, compared to virgin PA-12.

Advances in Aerospace Science and Technology

This study focuses on the stepwise procedure involved in the development of a numerical model of ... more This study focuses on the stepwise procedure involved in the development of a numerical model of a bi-propellant hypergolic chemical propulsion system using key features and performance characteristics of existing and planned (near future) propulsion systems. The study targets specific impulse of 100 N delivery performance of thrust chambers which is suitable for primary propulsion and attitude control for spacecraft. Results from numerical models are reported and validated with the Rocket Propulsion Analysis (RPA) computation concept. In the modelling process, there was proper consideration for the essential parts of the thruster engine such as the nozzle, combustion chamber, catalyst bed, injector, and cooling jacket. This propulsion system is designed to be fabricated in our next step in advancing this idea, using a combination of additive manufacturing technology and commercial off the shelf (COTS) parts along with non-toxic propellants. The two non-toxic propellants being considered are Hydrogen Peroxide as the oxidiser and Kerosene as the fuel, thus making it a low-cost, readily available and environmentally-friendly option for future microsatellite missions.

Space Operations: Contributions from the Global Community, 2017

Subsequent to the launch of the first Nigerian satellite into space in September 2003, the Nation... more Subsequent to the launch of the first Nigerian satellite into space in September 2003, the National Space Research and Development Agency (NASRDA), Abuja, Nigeria, has demonstrated peaceful use of outer space through the commercial, educational, humanitarian and governmental applications of its five successfully launched satellites so far. The nation has also maintained a sustainable national development since achieving this feat by joining other nations in space operations. Satellite operations are carried out indigenously by Nigerian engineers and scientists from the Mission Control Ground Station (MCGS), Abuja, Nigeria. Its three remote sensing satellites, NigeriaSat-1, NigeriaSat-X and NigeriaSat-2, and two communication satellites, NIGCOMSAT-1 and NIGCOMSAT-1R, have addressed the status of space operations and complied with its peaceful use of outer space. With the successful completion of its mission lifetime, NigeriaSat-1 which was in the Disaster Monitoring Constellation (DMC) was de-orbited after about 9 years of useful and peaceful satellite operations. During its mission lifetime, it responded to both local and international disasters including sustainable development campaigns initiated jointly or individually for satellites in the constellation such as Hurricane Katrina and the development of a national resource inventory showing land-use/land-cover mapping at 1:50,000 among others. In continuation of these recorded achievements, NigeriaSat-X and NigeriaSat-2 which are advanced Earth observation (EO) microsatellites equipped with enhanced imaging performance for improved capability and applications have equally witnessed improved satellite operations from the Abuja MCGS. NIGCOMSAT-1 and NIGCOMSAT-1R have also been applied in telemedicine, teleconferencing, data transfer, internet services, e-library, etc. In the course of our satellite operations, useful lessons have been learnt in the management and operations of more than one satellite from a single ground station for the remote sensing satellites. Therefore, in this paper, we review and share our operational experiences, achievements and future direction on our quest into space for sustainable development through the use of our remote sensing and communication satellites.

Proceedings of SPIE, Oct 1, 2001

Many companies are faced with quality improvement issues on a daily basis but their response to t... more Many companies are faced with quality improvement issues on a daily basis but their response to this problem varies. This paper discusses the improvement in the defect reporting system at a medium sized manufacturing company following the appointment of an experienced, motivated, design engineer to be dedicated to that task. It sets out the situation that the engineer inherited and details the changes that were incorporated; it assesses which were successful and which failed. Following a survey of current literature, it was seen that there is little written specifically on the subject of audited defect reporting. It is felt that this study goes some way to filling that void. A successful survey of engineering companies in Southern Hampshire reinforces the principle findings, that the emphasising of the Check part of Demming's Plan-Do-Check-Act cycle is a novel approach to the Quality Improvement Process, and that it has reduced the cost of rework by an audited 80% in a period of two years.

Proceedings of SPIE, Oct 1, 2001

The business enterprise has never been in greater need of Agility and the current trend will cont... more The business enterprise has never been in greater need of Agility and the current trend will continue unabated well into the future. It is now recognized that information system is both the foundation and a necessary condition for increased responsiveness. A successful implementation of Enterprise Resource Planning (ERP) can help a company to move towards delivering on its competitive objectives as it enables suppliers to reach out to customers beyond the borders of traditional market defined by geography. The cost of implementation, even when it is successful, could be significant. Bearing in mind the potential strategic benefits, it is important that the implementation project is managed effectively. To this end a project cost model against which to benchmark ongoing project expenditure versus activities completed has been proposed in this paper.

Arid Zone Journal of Engineering, Technology and Environment, 2019

Rural to urban migration still persists in Nigeria despite government’s claim of rural developmen... more Rural to urban migration still persists in Nigeria despite government’s claim of rural development programs. This situation if not checked portends negative signal for the already over-populated urban areas, particularly in areas of food security, sanitation, housing, crimes, etc. The development of rural areas is measured by the availability of infrastructures and economic opportunities that are available to the people. These infrastructures include: transportation infrastructure, educational infrastructure, healthcare infrastructure, energy infrastructure, water supply/sanitation infrastructure, information and communication technology (ICT) infrastructure and so on. Rural areas in Nigeria urgently require accelerated infrastructure development to alleviate poverty. When this is done rapid growth is ensured and poverty is drastically reduced. The world today has become increasingly reliant on information and communication technologies (ICT) and with it comes the need for societies...

In this research work, a structural optimization methodology is applied to generate a Frame model... more In this research work, a structural optimization methodology is applied to generate a Frame model that meets CubeSat Design Standards. The frame is further subjected to software simulation that encapsulates worst case launch scenarios. The validity of the frame design has been demonstrated by quasi-static and modal analyses, with the results being verified analytically using direct stiffness approach. All subsystems in this study were modelled as remote masses at their Centre of Gravity (C.G) positions, considering their Moments of Inertia (M.I). The mass location analysis was done for a presumed internal configuration with the subsystems arranged such that the Centre of Gravity (C.G) and Moment of Inertia (M.I) values satisfy the launch vehicle constraints. The mass of the proposed structure has been reviewed to meet design mass requirements of a picosatellite structure as a subsystem with a mass less than 20 per cent of overall design mass of 1.33kg. The frame is modelled to bear ...

Strength of Materials, 2015

The approach provides simulation of the gear design with high-precision profile configuration par... more The approach provides simulation of the gear design with high-precision profile configuration parameters to accurately predict its load capacity and stress state, which requires incessant efforts, as gear failure modes depend largely on its profile representation. The finite element analysis (FEA) is a well-known effective computational method, which many authors used to estimate the gear tooth strength against the primary failure modes of gears. This method is not only known to be time-consuming but often expensive, it employs approximate geometry that resulted in a coarse mesh. The tooth strength and deformation modes were obtained from a three-dimensional gear model based on the trivariate nonuniform rational B-splines (NURBS) under loading and investigated using the isogeometric analysis (IGA) for simulation. The results produced with the IGA simulation are compared with the corresponding values derived from the classical estimation method with the Lewis equation and FEM analysis using ANSYS. Both results are in good agreement and confirm that the IGA model is more accurate than the FEM one. This study demonstrated that IGA was practically applicable, providing an alternative means of using high-precision geometry of 3D models to estimate the behavior of gear bodies under loading and modify their strength calculations.

A detailed study of the effects of layer thickness, hatch spacing, hatch overcure depth, and hatc... more A detailed study of the effects of layer thickness, hatch spacing, hatch overcure depth, and hatch fill cure depth on the quality of the StereoLithography (SL) product was carried out using acrylic based resin. Taguchi Method was used for analysing all experimental results. The ANOVA and the Signal-to-noise ratio (SIN) results were used to select the optimum parameters and the appropriate factor levels for further experiments. A new hatch styIe with an optimum layer thickness is proposed for the build process with minimum geometrical distortion.

Polymer Testing, 2006

The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties o... more The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties of layered silicate nanoclay reinforced unsaturated polyester (UPE) nanocomposites were investigated by a nano-indentation test method. The clay was dispersed into a UPE matrix via blending using a mechanical stirrer. Structural studies were carried out using a wide angle X-ray diffraction (WAXD) method and correlated with the

This paper describes a flexible modular design approach applied to the design of a sealed lead ac... more This paper describes a flexible modular design approach applied to the design of a sealed lead acid vehicle battery charger. The design process is separated into sub-processes and the design is then checked against available modules and knowledge. Potentially useful modules are then identified and used if possible. Other new modules are then created to complete the design. New products can be created from available modules if possible and this simplifies the design process and makes the process cheaper.

2010 International Conference on Education and Management Technology, 2010

Lean Production is a time tested and trusted world class production system which does more and ac... more Lean Production is a time tested and trusted world class production system which does more and achieve more with less resources by eliminating waste and ensuring continuous improvement within its value stream. Understandably, it has today become the cynosure of all eyes and center of most scholarly discuss from all fields of human endeavor due to its acclaimed success. But its continuous mill of success seems to be slowing down and dwindling by the day due to the relegation almost to extinction of the intellectually unique Human Resource which is at the heart of the Lean philosophy. It is therefore expedient that the foundation principles and pillars of all lean practicing system especially its Human Resource foundation be fortified. This paper takes an in-depth look into the Human aspects in today's Lean practice.

Journal of Medical Engineering & Technology, 2009

Research into fabrication of hip joint replacements combines knowledge from distinct domains, suc... more Research into fabrication of hip joint replacements combines knowledge from distinct domains, such as engineering, materials and medical fields. Recent computer assisted technologies have played an important role in the medical field. Unlike the modelling of most of the human bones, the creation of an accurate 3D model of a pelvic bone has been a challenging task. The main source of difficulties in this case has proven to be the complexity of the structure of the pelvis, having basically a free-form shape with a hole in the middle constituting some over-shadowed areas (undercuts), various cavities, areas with high form curvature, variable wall thickness with some very thin sections and inside layers with different mechanical properties. In this research work, a pelvic bone is generated using reverse engineering, rapid prototyping and rapid tooling techniques. The geometric data obtained from reverse engineering through laser scanning are used and manipulated to create accurate 3D CAD representations of these devices. These CAD models can be used for various virtual tests and simulations, as well as for reproduction through rapid manufacturing processes and then used as prototypes in tooling, physical tests and planning of surgical operations.

New methods are presented for controlling, programming and automating advanced production machine... more New methods are presented for controlling, programming and automating advanced production machines. Object Oriented Programming is used to model Task Machines. A brief review is provided of machine, communication and machine programming classifications. Task Machines are created from Functional Machines and some benefits of using this method are described through a comparison with conventional Imperative and Functional Programming methods. Using the new methods can improve efficiency and flexibility of machine programming systems.

Polymer Testing, 2006

The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties o... more The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties of layered silicate nanoclay reinforced unsaturated polyester (UPE) nanocomposites were investigated by a nano-indentation test method. The clay was dispersed into a UPE matrix via blending using a mechanical stirrer. Structural studies were carried out using a wide angle X-ray diffraction (WAXD) method and correlated with the nanoindentation results. This shows that nanoindentation behaviour is strongly influenced by clay reinforcement and the degree of clay dispersion in the polymer matrix. The experimental results show that there is a strong correlation between nanomechanical properties and inter layer d-spacing of clay particles in the nanocomposite system. Incorporation of 1%, 3% and 5% by weight nanoclay into the polyester resin results in an improvement in hardness of 29%, 24% and 14%, respectively. The elastic modulus increased from 5393 MPa for unreinforced polyester to 6646 MPa (23% increase) with the introduction of 5% by weight nanoclay.

Proceedings of the World Congress on Engineering, 2010

Journal of Materials Processing Technology, 2003

Abstract An experimental investigation is made on the effects of die reduction in area, die angle... more Abstract An experimental investigation is made on the effects of die reduction in area, die angle, loading rate on the quality of the extrusion products, extrusion pressures and flow pattern of cold extruded aluminium and lead alloys shapes of inner circular sections with four symmetrical projections. The radii of curvature for both extruded lead and aluminium alloys and the average hardness values of the extruded products along the projections and along the circumferential solid positions are found to increase with increase in die reduction in area, and slightly with increase of the loading rates. It shows that the non-dimensionalised values of the specific coring pressures, Pc/ϕ, and maximum extrusion pressures, Pmax/ϕ, depend primarily on the die angle, loading rate and total reduction in area of the cross-section of the complex-shaped section. These are found to be minimum at a die angle of 90°, which is recommended for die design so as to minimise extrusion pressure and hence increase die life. Empirical formulae, relating the specific maximum extrusion pressure and coring pressure to the reduction in area, R, can be expressed in the form P/ϕ=a+b ln (1/(1−R)) , where a and b are constants for a given material. Similarly, empirical formulae of the form P/ϕ=a′+b′ ln (V) are used to express the extrusion pressures (maximum or coring) P/ϕ, to the extrusion speed. Extrusion defects and the flow patterns of the extruded complex-shaped section are highlighted and discussed.

Composites Part B: Engineering, 2012

The aim of this work was to study the structure and mechanical properties of spent polyamide-12 a... more The aim of this work was to study the structure and mechanical properties of spent polyamide-12 and spent polyamide-12/layered silicate reinforced novel nanocomposites. Layered silicate at 1, 3, 5 and 7 wt.% was incorporated in spent polyamide-12 and its nanocomposites were prepared using single screw injection moulding technique. The interlamellar structure and surface morphology were characterised by transmission electron microscope (TEM) and scanning electron microscope (SEM). Different levels of layered silicate dispersion (as characterised by TEM and SEM) correlated strongly with improvements in mechanical performance. The results showed that the tensile and flexural properties are found to be increased with the incorporation of layered silicate into spent PA-12 matrix. Comparison of tensile and flexural test results between virgin PA-12, spent PA-12 and spent PA-12 nanocomposites showed that spent PA-12 samples have retained 70% of its tensile and 80% of its flexural properties respectively, compared to virgin PA-12.

Advances in Aerospace Science and Technology

This study focuses on the stepwise procedure involved in the development of a numerical model of ... more This study focuses on the stepwise procedure involved in the development of a numerical model of a bi-propellant hypergolic chemical propulsion system using key features and performance characteristics of existing and planned (near future) propulsion systems. The study targets specific impulse of 100 N delivery performance of thrust chambers which is suitable for primary propulsion and attitude control for spacecraft. Results from numerical models are reported and validated with the Rocket Propulsion Analysis (RPA) computation concept. In the modelling process, there was proper consideration for the essential parts of the thruster engine such as the nozzle, combustion chamber, catalyst bed, injector, and cooling jacket. This propulsion system is designed to be fabricated in our next step in advancing this idea, using a combination of additive manufacturing technology and commercial off the shelf (COTS) parts along with non-toxic propellants. The two non-toxic propellants being considered are Hydrogen Peroxide as the oxidiser and Kerosene as the fuel, thus making it a low-cost, readily available and environmentally-friendly option for future microsatellite missions.

Space Operations: Contributions from the Global Community, 2017

Subsequent to the launch of the first Nigerian satellite into space in September 2003, the Nation... more Subsequent to the launch of the first Nigerian satellite into space in September 2003, the National Space Research and Development Agency (NASRDA), Abuja, Nigeria, has demonstrated peaceful use of outer space through the commercial, educational, humanitarian and governmental applications of its five successfully launched satellites so far. The nation has also maintained a sustainable national development since achieving this feat by joining other nations in space operations. Satellite operations are carried out indigenously by Nigerian engineers and scientists from the Mission Control Ground Station (MCGS), Abuja, Nigeria. Its three remote sensing satellites, NigeriaSat-1, NigeriaSat-X and NigeriaSat-2, and two communication satellites, NIGCOMSAT-1 and NIGCOMSAT-1R, have addressed the status of space operations and complied with its peaceful use of outer space. With the successful completion of its mission lifetime, NigeriaSat-1 which was in the Disaster Monitoring Constellation (DMC) was de-orbited after about 9 years of useful and peaceful satellite operations. During its mission lifetime, it responded to both local and international disasters including sustainable development campaigns initiated jointly or individually for satellites in the constellation such as Hurricane Katrina and the development of a national resource inventory showing land-use/land-cover mapping at 1:50,000 among others. In continuation of these recorded achievements, NigeriaSat-X and NigeriaSat-2 which are advanced Earth observation (EO) microsatellites equipped with enhanced imaging performance for improved capability and applications have equally witnessed improved satellite operations from the Abuja MCGS. NIGCOMSAT-1 and NIGCOMSAT-1R have also been applied in telemedicine, teleconferencing, data transfer, internet services, e-library, etc. In the course of our satellite operations, useful lessons have been learnt in the management and operations of more than one satellite from a single ground station for the remote sensing satellites. Therefore, in this paper, we review and share our operational experiences, achievements and future direction on our quest into space for sustainable development through the use of our remote sensing and communication satellites.