Papers by Lagouge Tartibu
Materials Today: Proceedings, 2019
A review about the optimization techniques used for modern machining techniques are analyzed in t... more A review about the optimization techniques used for modern machining techniques are analyzed in this paper. The chief focus is kept on the modern optimization techniques employed to obtain the optimal machining parameters and during both nonconventional machining processes. The various Non-traditional machining techniques analyzed for this study are the Wire Electro Discharge Machining (WEDM), Laser Beam Machining (LBM), Abrasive Water Jet Machining (AWJM) and Electro Discharge Machining (EDM). These machining processes were analyzed with respect to different modern optimization techniques. The most widely used, frequently used and rarely used optimization techniques for the mentioned non-conventional machining processes are identified. The paper provides an overall idea about the optimization techniques and helps to choose the suitable technique for the researchers.
Advances in Materials and Processing Technologies
International Journal of Green Energy
Procedia Computer Science, 2023
Volume 2B: Advanced Manufacturing
Milling is one of the old and common cutting processes that utilize rotating tools to take materi... more Milling is one of the old and common cutting processes that utilize rotating tools to take materials off the main component with a combination of tools and workpiece movements. The texture of a machined surface is a key factor in defining how an essential component interacts with its environment. Trial-and-error machining to produce high-quality surfaces has been a time-consuming method that yields lower production and poor revenue. In this paper, the performances of an Adaptive Network-based Fuzzy Inference System (ANFIS) model has been employed for the prediction of the surface roughness (SR) of a block of Aluminum alloy AI6061 machined on an end-mill CNC machine by varying four input settings namely: The spindle speed of rotation, the tool cutting rate, the radial depth, and the axial depth. The approach consisted of a parametric analysis carried out within each system to obtain the finest models for the prediction. The hybrids ANFIS-PSO and ANFIS-GA have been employed to find ou...
Abstract: In this paper, we highlight the effects of contaminated water on humans as well as the ... more Abstract: In this paper, we highlight the effects of contaminated water on humans as well as the crisis of water supply and distribution of potable water in many areas of developing countries. Water is the most important substance on earth. While water is a primary human need, contaminated water can cause and spread diseases. It is, therefore, necessary to ensure that water is purified and decontaminated for daily use at a low-cost. Therefore, the design of solar-powered water purification systems is considered to produce clean water. Solar energy poses no polluting effect; thus, has become a dependable energy source for usage. The design of a solar-powered water purification system is based totally on the thermal method by using the thermal heating system principle. This principle converts sunlight rays into heat. The most vital aspect is the absorption of heat to induce evaporation of water. Research shows that flat plate collectors produce heat at relatively low temperatures (27°...
2020 IEEE 11th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT)
The accumulative roll-bonding process (ARB) was performed on commercially available AL-1050-H4 al... more The accumulative roll-bonding process (ARB) was performed on commercially available AL-1050-H4 aluminum alloy. Samples were rolled for two passes. In ARB process, thickness is reduced by 50% for each pass. The aim of performing the ARB process was to refine the grain structure of aluminum 1050-H4 to increase its tensile strength. A tensile test was performed at room temperature and at a steady strain rate with the aim of determining whether ARB increases the mechanical properties of aluminum 1050-H4 and identify the moment the material experience high ultimate tensile strength. Samples were cut according to standard test methods for tension testing of metallic material (ASTM) at rolling direction (RD). Information about the microstructure of samples was obtained using a scanning electron microscope (SEM). The highest UTS was obtained on the 1st pass and was reported as 127.1 MPa and the lowest UTS was discovered on parent sample and reported as 111.7 MPa. It was also observed that E-modulus and percentage elongation decreased due to the ARB process. It was noticed that after several rolling process, material surface temperature increases. The increase in surface temperature led to increase in particle size which was discovered on 2nd pass of ARB process which result in material losing its mechanical properties
2019 6th International Conference on Soft Computing & Machine Intelligence (ISCMI), 2019
Mine fatalities, accidents and incidents are often associated with ground, roof, stope or side in... more Mine fatalities, accidents and incidents are often associated with ground, roof, stope or side instability. Attenuation of rock integrity or the presence of (under)ground pockets of gases or ground waters lead to the collapse of the tunnel. In this paper, the blast vibration in an Open-pit Lignite Mine has been predicted by incorporating the frequency, the charge per delay, the distance and scaled distance using Artificial Neural Network (ANN). The particle velocities (PPV) namely transverse peak, vertical peak and longitudinal peak are successively the output parameters considered. Particle Swarm Optimization (PSO) was used to train the neural network with 54 experimental and monitored blast records. Results were compared based on correlation between monitored and predicted values of PPV. This study demonstrates the possibility to predict and control blasting effect.
2017 International Conference on the Industrial and Commercial Use of Energy (ICUE), 2017
This work describes the design and construction of a standing wave Thermoacoustically Driven Ther... more This work describes the design and construction of a standing wave Thermoacoustically Driven Thermoacoustic Refrigerator (TADTAR). The thermoacoustic cooler is proposed in this study as an alternative sustainable solution to current issues with vapor compression refrigerators, due to its environmentally friendlier attributes and its solar energy driven capabilities. However, one of the main hindrances to the expansion of this technology is its current lack of efficiency and performance closely related to the designing of the device. Hence, a model has been designed and constructed to perform an experimental investigation of the device's performance at the University of Johannesburg. This model will mainly be used to investigate the dynamics of the TADTAR arrangement. The TADTAR consists of two thermoacoustic systems namely a thermoacoustic engine coupled to a thermoacoustic refrigerator. The thermoacoustic engine consists of a heat source and a cordierite honeycomb stack which converts heat into acoustic energy. The heat pumping takes place within a thermoacoustic refrigerator. Guidance on the material selection, constraints and calculation of the geometrical configuration describing the device constitute the main contribution of this work.
Volume 8: Heat Transfer and Thermal Engineering, 2019
Thermo-acoustic refrigeration could potentially become an alternative option to current tradition... more Thermo-acoustic refrigeration could potentially become an alternative option to current traditional refrigeration systems provided that the issue related to its efficiency is addressed. One of the incentives for developing this technology is the opportunity it establishes with respect to the use of a sustainable heat source to induce cooling. Many existing works have pointed out the relationship between the geometrical configuration of the device and its performance. Mainly, the stack geometry and position have been the focus of these previous works. In this work, a standing-wave ThermoAcoustically-Driven Thermo-Acoustic Refrigerator with an adjustable resonator has been developed. Hence the device is made of two portions, joined with an adjustable duct, namely a simple standing-wave thermo-acoustic engine that converts heat into a sound wave and a simple thermo-acoustic refrigerator where heat pumping takes place. The Design Environment for Low-amplitude ThermoAcoustic Energy Conve...
2020 IFEES World Engineering Education Forum - Global Engineering Deans Council (WEEF-GEDC), 2020
The International Engineering Alliance has developed graduate attributes to improve the employabi... more The International Engineering Alliance has developed graduate attributes to improve the employability of engineering graduates and to reduce the gap between academic work and practice. The three main accords that form part of this international alliance are the Washington Accord, the Sydney Accord, and the Dublin Accord. All countries that belong to these accords have developed graduate attributes for accreditation purposes. Embedding graduate attributes into the curriculum can be complex and would depend on academic staff involvement. Hence, the necessity to determine how best graduate attributes can be developed and give clarity about assessment strategies. Engineering faculties need to consider developing clear processes that clarify the programme outcomes assessment in the context of graduate attributes. This paper provides an overview of some practical approaches that could be used for the development of graduate attribute assessments.
2020 IEEE 11th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT), 2020
the effect of surface temperature and particle size on mechanical properties (hardness) of AL 105... more the effect of surface temperature and particle size on mechanical properties (hardness) of AL 1050-H4 alloy strip of 1.6mm thickness, 25mm width and 1250mm length have been investigated in this paper. The research focus on the influence of surface temperature of nanomaterials during grain refinement by accumulative roll bonding (ARB) at room temperature of 24°c. The material thickness was reduced by 49% for the first pass and the temperature measured on the surface was 27.2°c. For the second pass the thickness was reduced by 50% with a temperature of 29.5°c. Deformed samples were observed with light polarized microscope (LPM). Micro-hardness test was performed on rolled samples as well as on parent sample. It was observed that particles sizes decrease on the first pass where the surface temperature 27.2°c and Start to grow on second pass of ARB process when the surface temperature continuously increases. High material hardness was observed where the particle sizes are small and start to decrease when the material experience particle growth due to increase in temperature.
2018 International Conference on the Industrial and Commercial Use of Energy (ICUE), 2018
This work proposes the use of Artificial Neural Network (ANN) as a new approach to determine the ... more This work proposes the use of Artificial Neural Network (ANN) as a new approach to determine the future level of energy consumption in South Africa. Particle Swarm Optimization (PSO) was used in order to train Artificial Neural Networks. The population size, the percentage losses, the Gross Domestic Product (GDP), the percentage growth forecasts, the expected Final Consumption Expenditure of Households (FCEH) as well as the relevant manufacturing and mining indexes are the "drivers" values used for the forecasts. Three growth scenarios have been considered for the forecasting namely low, moderate and high (less energy intensive) scenarios. These inputs values for the period of 2014 to 2050, from the Council for Scientific and Industrial Research (CSIR), were used to test data and validate the use of this new approach for the prediction of electricity demand. An estimate of the annual electricity demand forecasts per scenario was calculated. Besides the speed of the computa...
paper examines the modal analysis techniques applied in experiments using a uniform and a stepped... more paper examines the modal analysis techniques applied in experiments using a uniform and a stepped beam. These simplified shapes are representative of the a wind turbine blade. Natural frequencies have been identified, therefore designers can ensure those natural frequencies will not be close to the frequency of the main excitation forces (1P or N b P with Nb being the number of rotor blades) in order to avoid resonance. The turbine blade is approximated by a cantilever, therefore, it is fully constrained where attached to a turbine shaft/hub. Flap-wise, edge-wise and torsional natural frequencies are calculated. The results found have been compared to numerical results and the exact solution of an Euler-Bernoulli beam. Concurrence is found for the frequency range of interest. Although, some discrepancies exist at higher frequencies (above 500 Hz), finite element analysis proves to be reliable for calculating natural frequencies.
This work describes the design and construction of a four-stage traveling-wave thermo-acoustic sy... more This work describes the design and construction of a four-stage traveling-wave thermo-acoustic system for electricity generation. The thermo-acoustic conversion consists of using a sound-wave for the transfer of heat from a low to high-temperature medium or the use of heat energy to generate a sound wave. Both the absence of moving parts and the simplicity of thermo-acoustic systems make the technology sustainable for converting low-grade waste heat into acoustic power. Many existing studies have pointed out the acoustic-to-electric potential of thermo-acoustic systems. Hence in this work, a thermo-acoustic system has been developed. The traveling-wave system has a total length of 3 560 mm. The distance between each thermo-acoustic engine is 640 mm. Each engine stage had four cartridge heaters used to generate the heat required. A commercial loudspeaker was used to convert sound into electricity. The minimum temperature difference necessary to induce a voltage at the terminals of the loudspeaker was approximately 200°C. The four-stage traveling-wave system generated the highest output voltage of 4.218 V.
Volume 12: Advanced Materials: Design, Processing, Characterization, and Applications, 2019
In this paper, the Atomic Layer Deposition (ALD) process in the reactor scale was simulated using... more In this paper, the Atomic Layer Deposition (ALD) process in the reactor scale was simulated using ANSYS® Fluent® 19.1 and ChemKin-PRO commercial packages in order to solve transport and chemistry equations. Trenched substrates with large aspect ratios (AR) of 33 ≤ AR ≤ 300, at a reactor scale of an ALD process, were considered a temperature of 473K and 573K. Trimethlyaluminum (TMA) and Ozone reactants were used to formulate a precise Sticking Coefficients (SC) for a satisfactory dose (precursor exposure level) in order to deposit conforming Al2O3 films. The estimated error in the empirical correlation of SCs was determined and compared to published experimental data. An empirical correlation based on simulated models was derived. This correlation can be exploited to determine precise precursor exposure levels for an ALD process irrespective of the type of reactor used.
2017 International Conference on the Industrial and Commercial Use of Energy (ICUE), 2017
Cool roofs are beneficial for most buildings almost everywhere in the world. They are described a... more Cool roofs are beneficial for most buildings almost everywhere in the world. They are described as an inexpensive method in order to improve the comfort level in buildings in mild and hot climate and to save energy. However, their cost-effectiveness can vary significantly, depending on climate and local factors. Therefore, the use of simulations with local conditions can provide the clarity required in order to deploy cool roofs in a particular location. This paper presents an estimation of the potential energy savings resulting from the use of cool roofs for different climatological conditions within South Africa. Several cities have been selected across South Africa and climatological data have been obtained from the NASA Atmospheric Science Data Center. The DOE Cool Roof Calculator was adapted for the estimation of cooling and heating saving corresponding to specific type of roofs and climatological variables within these selected cities. The preliminary results strongly suggest ...
SSRN Electronic Journal, 2020
This work describes the development and assessment of a three-stage thermo-acoustic electricity g... more This work describes the development and assessment of a three-stage thermo-acoustic electricity generator that demonstrate the potential of conversion of waste heat into useful electricity. A three-stage travelling-wave thermo-acoustic system was constructed and tested. The effect of the heat source on the potential of the device to generate electric power is analysed. Theloudspeakerhad used for the acoustic-to-electricity conversion in this research study. The onset temperature difference, the onset time,and the magnitude of the electricity generated has considered as the performance indicators of the device developed. This paper provides details of the experimental investigation that consists of measuring the temperatures, the frequency of the sound-wave, and the acoustic power generated using thermocouples and sound level meter coupled to data acquisition for signal processing and visualization. Electric power supplied to the cartridge heaters at a maximum voltage range of 150 to 190 Volts. The effect of the geometrical configuration of the device concerning acoustic-to-electricity with electricity conversion is analysed. The best geometrical arrangement for generating electricity at the lowest onset temperature difference had identified.The three-stage travelling-wave system generated the highest output voltage of approximately 2.4 V.
Engineering Optimization, 2019
This article proposes the use of an improved version of the ε-constraint method for the design an... more This article proposes the use of an improved version of the ε-constraint method for the design and optimization of a rectangular micro-channel heat sink. This study aims to optimize the geometric parameters describing the micro-channel, namely its width, its fin width and its depth. The thermal resistance and the pumping power, considered as indicators of the thermal performance, have been approximated by surrogated models based on response surface approximation. The optimization task is formulated as a nonlinear programming problem. This approach has been implemented in GAMS. Sufficient details on both the single-criterion and multi-criteria formulation of the problem have been provided. The implications of the mathematical modelling formulation and the interrelationship between criteria and estimated quantities have been clarified. The use of the augmented-constraint method for the multi-objective optimization of a rectangular micro-channel heat sink constitutes the main contribution of this work.
Sustainable Energy Technologies and Assessments, 2019
The use of hazardous refrigerants in current refrigeration systems and their impact on environmen... more The use of hazardous refrigerants in current refrigeration systems and their impact on environment have spurred much research into alternative technologies. Thermo-acoustic refrigeration is considered as one of the potential solution to the current search for environmental friendlier technology because of the absence of harmful refrigerants in the system. To date, most of the studies focus on the applicability of the technology toward a global agenda of a sustainable future. This paper summarizes recent development with regards to the designing and the performance of highly efficient traveling-wave thermo-acoustic refrigerators. Past studies discussing devices outputs namely the lowest temperature achieved, the cooling power and the coefficient of performance of travelling-wave refrigerators, are described. The review looks at the performance and the geometrical configuration of devices developed by previous researchers. A summary of the optimization targets and the outcomes achieved is described. It appears that most studies undertaken so far rely heavily on parametric approach, with single parameter being investigated while the others are kept constant during the optimization process. This opens the door for further use of advanced optimization techniques able to deal with parameters varying simultaneously, together with conflicting objectives, in order to identify global optimal solutions potentially more effective.
Uploads
Papers by Lagouge Tartibu
This work explores the use of a multi-objective optimisation approach to model and to optimise the performance of a simple thermoacoustic engine. This study aims to optimise its geometrical parameters—namely the stack length, the stack height, the stack position, the number of channels and the plate spacing—involved in designing thermoacoustic engines. System parameters and constraints that capture the underlying thermoacoustic dynamics have been used to define the models. Acoustic work, viscous loss, conductive heat loss, convective heat loss and radiative heat loss have been used to measure the performance of the thermoacoustic engine. The optimisation task is formulated as a five-criterion mixed-integer nonlinear programming problem. Since we optimise multiple objectives simultaneously, each objective component has been given a weighting factor to provide appropriate user-defined emphasis. A practical example is provided to illustrate the approach. We have determined a design statement of a stack describing how the design would change if emphasis is placed on one objective in particular. We also considered optimisation of multiple objective components simultaneously and identified global optimal solutions describing the stack geometry using the augmented ε-constraint method. This approach has been implemented in GAMS (General Algebraic Modelling System).
In addition, this work develops a novel mathematical programming model to optimise the performance of a simple thermoacoustic refrigerator. This study aims to optimise its geometrical parameters—namely the stack position, the stack length, the blockage ratio and the plate spacing—involved in designing thermoacoustic refrigerators. System parameters and constraints that capture the underlying thermoacoustic dynamics have been used to define the models. The cooling load, the coefficient of performance and the acoustic power loss have been used to measure the performance of the device. The optimisation task is formulated as a three-criterion nonlinear programming problem with discontinuous derivatives (DNLPs). Since we optimise multiple objectives simultaneously, each objective component has been given a weighting factor to provide appropriate user-defined emphasis. A practical example is provided to illustrate the approach. We have determined a design statement of a stack describing how the geometrical parameters described would change if emphasis is placed on one objective in particular. We also considered optimisation of multiple objective components simultaneously and identified global optimal solutions describing the stack geometry using a lexicographic multi-objective optimisation scheme. The unique feature of the present mathematical programming approach is to compute the stack geometrical parameters describing thermoacoustic refrigerators for maximum cooling or maximum coefficient of performance.
The present study highlights the importance of thermal losses in the modelling of small-scale thermoacoustic engines using a multi-objective approach. The proposed modelling approach for thermoacoustic engines provides a fast estimate of the geometry and position of the stack for maximum performance of the device. The use of a lexicographic method introduced in this study improves the modelling and the computation of optimal solutions and avoids subjectivity in aggregation of weight to objective functions in the formulation of mathematical models. The unique characteristic of this research is the computing of all efficient non dominated Pareto optimal solutions allowing the decision maker to select the most efficient solution.
The present research experimentally examines the influence of the stack geometry and position on the performance of thermoacoustic engines and thermoacoustic refrigerators. Thirty-six different cordierite honeycomb ceramic stacks are studied in this research. The influence of the geometry and the stack position has been investigated. The temperature difference across the stack and radiated sound pressure level at steady state are considered indicators of the performance of the devices. The general trends of the proposed mathematical programming approach results show satisfactory agreement with the experiment.
One important aspect revealed by this study is that geometrical parameters are interdependent and can be treated as such when optimising the device to achieve its highest performance. The outcome of this research has direct application in the search for efficient stack configurations of small-scale thermoacoustic devices for electronics cooling.
The MATLAB program “BEAMANALYSIS.m” has been developed for the finite element analysis of a one dimensional model of the beam. Similarly, a three dimensional model of the beam has been developed in a finite element program Unigraphics NX5. The results found using the MATLAB program are compared with those found with NX5. Satisfactory agreement between the results is found for frequencies up to almost 500 Hz. Additionally, the frequencies one might expect in an experiment are identified.
Experimental modal analysis has been performed on a uniform and stepped beam made of mild steel to extract the first five flap-wise natural frequencies. The results found have been compared to numerical results and the exact solution of an Euler-Bernoulli beam. Concurrence is found for the frequency range of interest. Although, some discrepancies exist at higher frequencies (above 500 Hz), finite element analysis proves to be reliable for calculating natural frequencies.
Finally, the fixed portion and moveable portion of the variable length blade are approximated respectively by a hollow and a solid beam which can be slid in and out. Ten different configurations of the variable length blade, representing ten different positions of the moveable portion are investigated. A MATLAB program named VARIBLADEANALYSIS.m was developed to predict natural frequencies. Similarly three dimensional models of the variable length blade have been developed in the finite element program Unigraphics NX5.
L’intérêt de ces systèmes est double:
Détecter une anomalie le plus tôt possible
Réaliser un diagnostic complet pour en identifier les causes.
En surveillant l’apparition de défauts critiques, on peut prévoir les pannes et en minimiser les conséquences, les réparations sont réalisées au moment opportun, elles sont moins coûteuses et les arrêts de production sont limités et surtout justifiés. On essaie ainsi d’anticiper les ruptures d’outil qui peuvent endommager la machine.
Cette approche moderne de maintenance consiste à mesurer l’état d’une machine pendant son fonctionnement afin de n’intervenir que lorsque les paramètres l’indiquent. Il s’agit de la maintenance prédictive. Dans le cadre de cette étude, nous nous appesantirons sur le paramètre qui s’avère être le plus fiable dans la mesure où il donne le plus précocement et de la meilleure façon l’état de détérioration d’une machine tournante. Il s’agit des vibrations.
Le présent travail énonce et analyse les principes de mise en oeuvre de la maintenance prédictive, relève son intérêt économique et technique, justifie son choix en regard de toutes les techniques de maintenance. Ils présentent les différentes méthodes utilisées pour la détection des défauts sur les machines industrielles par le contrôle des vibrations.
Pour atteindre les objectifs ci-dessus présentés, le présent travail est structuré selon le plan suivant :
o Le premier chapitre concerne les vibrations mécaniques, leurs évaluations dans le cadre de la maintenance prédictive, l’analyse de ceux-ci ainsi que les informations indispensables pour leurs traitements.
o Le deuxième chapitre présente les concepts nécessaires à la compréhension de la maintenance prédictive par rapport à l’intérêt économique et technique poursuivi parla maintenance des équipements industriels. L’intégration des vibrations dans le cadre de la maintenance prédictive étant mis en évidence.
o Le troisième chapitre concerne les méthodes de détection des défauts. Il présente les principales activités utilisées pour la détection des défauts des machines tournantes.
o Le quatrième chapitre traite des défauts et de leurs manifestations vibratoires. Il présente les principaux défauts observables sur les machines tournantes, leurs manifestations et leurs origines ainsi que le principe d’établissement des niveaux d’alarme et de pré alarme sur les machines.
o Le cinquième chapitre concerne la prédiction de l’amplitude vibratoire à l’aide du logiciel MATLAB. Il présente de quelle manière le diagnostic prédictif peut être réalisé en s’appuyant sur un programme de prédiction qui est présenté.
refrigerator (TAR). This study aims to optimize the geometric variables namely the stack position, the stack length, the blockage ratio and the plate spacing involved in designing thermoacoustic refrigerators. Unlike most previous studies, these variables are considered interdependent. System parameters and constraints that capture the underlying thermoacoustic dynamics have been used to define the models. The cooling load, the coefficient of performance and the acoustic power loss have been used to measure the performance of the device. The optimization task is formulated as a three-criterion nonlinear programming problem with discontinuous derivatives (DNLP). A practical example considering three different gases is given to illustrate the approach. This approach has been implemented in the software GAMS (General Algebraic modelling System) and Pareto optimal solutions describing the most preferred geometry for maximum performance of the device are computed using the augmented Epsilon-constraint
method.