Faculty of Engineering

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Causes of delays in highway construction projects in Ghana
(Civil and Environmental Research, 2016) Aforla, B.; Woode, A.; Amoah, D. K.
Delays in construction projects are a global phenomenon, causing a multitude of negative effects on the key project participants – clients, consultants, and contractors. The main purpose of this study is to identify the causes of delay of highway construction projects in Ghana to determine the most important to the key project participants. Literature review and semi-structured interviews of 12 key players in the implementation process were conducted. Thirty five possible causes of delay were identified and further grouped into ten categories. A questionnaire survey was conducted on the resulting list of delay causes for the identification of the most important causes of delay. The relative importance of the individual causes were determined and ranked by their Relative Importance Index. The findings revealed that the five most important causes of delay in road construction projects in Ghana are 1) Delay in honouring payment certificates 2) Equipment failure 3) Shortage of materials 4) Poor site management 5) Late delivery of materials on site. It is hoped that the findings of this paper will help project participants to act on critical causes to minimize delay of their projects.
The use of lean thinking in managing productivity; a case of crystal-clear filtered drinking water.
(International Journal of Engineering Trends and Technology (IJETT), 2016) Govi, D. K.; Nyanor, P.; Deku, A.
A stochastic weather generator model for hydroclimatic prevision in urban floods risk assessment in Abidjan District (Cote d’Ivoire).
(Sustainability, 2016) Danumah, J. H.; Odai, S. N.; Saley, M. B.; Szarzynski, J.; Adjei, K.; Kouame, F. K.
Flood risk occurrence is very often related to heavy precipitation; and available future weather data is a potential source for long term flood risk prediction. The aim of this paper was to determine and analyze trends in rainfall, temperature and PET under present and future climatic conditions using Long Ashton Research Science-Weather Generator (LARS-WG) software, in prediction of flood risk occurrence in Abidjan. This work was based on the integration of Hydro climatic daily data within LARS-WG software. The processing steps are: (1) calibrating and validating the model using 50 years measured data, (2) generating baseline data for 50 years, (3) processing future scenario data based on baseline already set using HADCM3 and (4) Comparing baseline and generated scenario data. The resulting statistics show that temperature will increase by 0.32, 1.36 and 2.54 °C for the periods 2011–2030, 2046–2065 and 2080–2099 respectively. Then rainfall in the same period will increase by 4 %, 6 % and 10 % respectively. The mean and high flooding risk will then increase in long term within this urban area. Thus this future large extension of flooding occurrence imposes to take future weather scenario into account in prediction and management of flooding risk in Abidjan District.
Investigation of pulse electrochemical sawing machining of micro-inner annular groove on metallic tube
(International Journal of Machine Tools and Manufacture, 2016) Liu, G. X.; Zhang, Y. J.; Jiang, S. Z.; Liu, J. W.; Gyimah, G. K.; Luo, H. P.
Pulse electrochemical sawing micro-machining (PECSM) is a non-conventional process. Having features of no tool wear, no cutting force, and good surface quality, this process is suitable for machining micro-grooves on the inner wall of hole. The rotating dentate cathode (RDC) is beneficial for the distribution of electrolyte and electrolytic products removal, thus reducing the effects of concentration polarization on the electrochemical reaction. This study focuses on the PECSM of micro-inner annular groove on 304 stainless steel tube using a pH-neutral NaClO3 electrolyte. To study the effects of RDC on the process, the bubble layer structure (BLS) adhered to the surface of RDC was photographed using a high-speed camera. Under the condition of immersion, the symmetric distribution of two kinds of BLS adhered to the RDC surface. The four selected parameters (radius of dentate cathode, rotational speed of RDC, initial gap, feed rate) with different levels were carried out to study the process of PECSM micro-inner annular grooves on 304 stainless steel tube. Experimental results indicate that PECSM has high potential for machining micro-inner annular groove on metallic tube. A micro-inner annular groove that is 340 μm in depth and 263 μm in width was fabricated on a 304 stainless steel tube.
Quantifying total viable count in pork meat using combined hyperspectral imaging and artificial olfaction techniques.
(Food Analytical Methods, 2016) Li, H.; Kutsanedzie, F. Y.; Zhao, J.; Chen, Q.
Total viable count (TVC) of bacteria is one of the most important indexes in evaluation of quality and safety of meat. This study attempts to quantify the TVC content in pork by combining two nondestructive sensing tools of hyperspectral imaging (HSI) and artificial olfaction system based on the colorimetric sensor array. First, data were acquired using HSI system and colorimetric sensors array, respectively. Then, the individual characteristic variables were extracted from each sensor. Next, principal component analysis (PCA) was used to achieve data fusion based on these characteristic variables from two different sensor data for further multivariate analysis. In developing the models, linear (PLS and stepwise MLR) and nonlinear (BPANN and SVMR) pattern recognition methods were comparatively employed, and they were optimized by cross-validation. Compared with other models, the SVMR model achieved the best result, and the optimum results were achieved with the root mean square error of prediction (RMSEP) = 2.9913 and the determination coefficient (R p ) = 0.9055 in the prediction set. The overall results showed that it has the potential in nondestructive detection of TVC content in pork meat by integrating two nondestructive sensing tools of HSI and colorimetric sensors with SVMR pattern recognition tool.
Feasibility study on nondestructively sensing meat's freshness using light scattering imaging technique.
(Meat Science, 2016) Li, H.; Sun, X.; Pan, W.; Kutsanedzie, F. Y.; Zhao, J.; Chen, Q.
Rich nutrient matrix meat is the first-choice source of animal protein for many people all over the world, but it is also highly susceptible to spoilage due to chemical and microbiological activities. In this work, we attempted the feasibility study of rapidly and nondestructively sensing meat's freshness using a light scattering technique. First, we developed the light scattering system for image acquisition. Next, texture analysis was used for extracting characteristic variables from the region of interest (ROI) of a scattering image. Finally, a novel classification algorithm adaptive boosting orthogonal linear discriminant analysis (AdaBoost–OLDA) was proposed for modeling, and compared with two classical classification algorithms linear discriminant analysis (LDA) and support vector machine (SVM). Experimental results showed that classification results by AdaBoost–OLDA algorithm are superior to LDA and SVM algorithms, and eventually achieved 100% classification rate in the calibration and prediction sets. This work demonstrates that the developed light scattering technique has the potential in noninvasively sensing meat's freshness.
PTFE and MoS2 Additives for Mineral Oil Film Formation in EHL Point Contacts.
(ASME, 2016) Gyimah, G. K.; Guo, Z.; Huang, P.; Jiang, S.; Barber, G. C.
Lubricant film-forming viscosity index improvers blended with commercial engine oil have been developed and studied by using optical interferometry. The influence of the viscosity index improvers (PTFE and MoS2) mixed with oil were experimentally studied and compared with engine oil without the index improvers as the baseline. The effect of the viscosity index improvers on lubricant film thickness, contact pressure and rolling speed for the case of a steel ball loaded on a flat glass surface in point contact condition was investigated. An optical interferometry technique which utilized a monochromatic two-beam interferometry light source, a microscope and a high-speed video recording device was used for the investigation. Hamrock and Dawson calculations for EHL film thickness were also used for comparative analysis. The lubricants used were commercial SAE #30 engine oil and PTFE and MoS2 mixed with commercial SAE #30 engine oil. The oil viscosities ranged from 0.0109 Pa.s to 0.255 Pa.s. The rolling speed and the loads were varied between 0.189 m/s to 0.641 m/s and 1 N to 2.6 N respectively. The lubricant film thickness stability at the point of contact between the steel ball and the glass disc was investigated for both steady and rolling state conditions. The viscosity index improvers were found to have a significant effect on the film thickness behavior under pure rolling point contact conditions.
Staple food fortification for malnourished children and pregnant women in Northern Ghana.
(International Journal of Engineering Research, 2016) Okwabi, R.; Sampare, S. A.
Most people in rural Africa and other developing countries take in food that is not sufficiently rich in nutrient. The reason for this deficiency is because of poverty, specifically lack of money to buy proper dietary food or ignorant in consuming the right nutritional food is of concerned. This phenomenon had led to many health problems such as anemia, night blindness, high maternal mortality rate, brain damage and the rest. Many people in Northern Ghana are deficient in micro-nutrient intake, particularly children and pregnant women. The quickest and cost effective way is through the fortification process. The White maize flour which is the staple food for people living in Northern Ghana can be increased by missing with a premix (Super cereal Plus). The fortification process was carried with a low cost technology of Hand Operated Mixer Machine. A 0.0175:50 kg premix-white maize flour was estimated to be the standard nutrition needed by malnourished children and pregnant women. Homogeneous of the food fortification was achieved with the Hand Operated Mixer Machine, however, attention must be given on modification of the machine, particularly for ease of operation and at a lower cost.
Original framework for optimizing hybrid energy supply.
(Journal of Energy, 2016) Acakpovi, A.
This paper proposes an original framework for optimizing hybrid energy systems. The recent growth of hybrid energy systems in remote areas across the world added to the increasing cost of renewable energy has triggered the inevitable development of hybrid energy systems. Hybrid energy systems always pose a problem of optimization of cost which has been approached with different perspectives in the recent past. This paper proposes a framework to guide the techniques of optimizing hybrid energy systems in general. The proposed framework comprises four stages including identification of input variables for energy generation, establishment of models of energy generation by individual sources, development of artificial intelligence, and finally summation of selected sources. A case study of a solar, wind, and hydro hybrid system was undertaken with a linear programming approach. Substantial results were obtained with regard to how load requests were constantly satisfied while minimizing the cost of electricity. The developed framework gained its originality from the fact that it has included models of individual sources of energy that even make the optimization problem more complex. This paper also has impacts on the development of policies which will encourage the integration and development of renewable energies.
Flood risk assessment and mapping in Abidjan district using multi-criteria analysis (AHP) model and geoinformation techniques (Cote d’ivoire).
(Geoenvironmental Disasters, 2016) Danumah, J. H.; Odai, S. N.; Saley, B. M.; Szarzynski, J.; Thiel, M.; Kwaku, A.; Akpa, L. Y.
Background: Flood is one of the most destructive natural disasters of climate change effects in West Africa. Flood risk occurrence is a combination of natural and anthropogenic factors, which calls for a better understanding of its spatial extent. The aim of this paper is to identify, and map areas of flood risk in Abidjan district. Results: This work is based on the integration of multi-criteria data including slope, drainage density, type of soil, Isohyet, population density, land use and sewer system density within ArcGIS interface. The resulting AHP flood risk map shows that areas under high and very high flood risk covers 34 % of the study area. Conclusion: The Analytic Hierarchy Process (AHP) method used as a multi-criteria analysis allowed the integration of several elements under two criteria, hazards and vulnerability, for flood risk assessment and mapping. Results revealed that, Abidjan district is heavily exposed to the risk of flooding. Eight out of thirteen (8/13) municipalities within the district are at a high risk of flooding which calls for decision makers to effectively develop strategies for future flood occurrences within the Abidjan district (South of Côte d’Ivoire).
An investigation of health and safety measures in a hydroelectric power plant.
(Safety and Health at Work, 2016) Acakpovi, A.; Dzamikumah, L
Background: Occupational risk management is known as a catalyst in generating superior returns for all stakeholders on a sustainable basis. A number of companies in Ghana implemented health and safety measures adopted from international companies to ensure the safety of their employees. However, there exist great threats to employees' safety in these companies. The purpose of this paper is to investigate the level of compliance of Occupational Health and Safety management systems and standards set by international and local legislation in power producing companies in Ghana. Methods: The methodology is conducted by administering questionnaires and in-depth interviews as measuring instruments. A random sampling technique was applied to 60 respondents; only 50 respondents returned their responses. The questionnaire was developed from a literature review and contained questions and items relevant to the initial research problem. A factor analysis was also carried out to investigate the influence of some variables on safety in general. Results: Results showed that the significant factors that influence the safety of employees at the hydroelectric power plant stations are: lack of training and supervision, non-observance of safe work procedures, lack of management commitment, and lack of periodical check on machine operations. The study pointed out the safety loopholes and therefore helped improve the health and safety measures of employees in the selected company by providing effective recommendations. Conclusion: The implementation of the proposed recommendations in this paper, would lead to the prevention of work-related injuries and illnesses of employees as well as property damage and incidents in hydroelectric power plants. The recommendations may equally be considered as benchmark for the Safety and Health Management System with international standards.
Improvers of pressure-viscosity coefficients of two-phase liquid-solid lubricants.
(2016) Gyimah, G. K.; Guo, Z. N.; Huang, P.; Jiang, S. Z.; Barber, G. C.; Liu, G. X.; Liu, J. W.
The prediction of the pressure-viscosity coefficient, α, is one of the most important properties for Elastohydrodynamic lubrication (EHL) condition; thereby, the need for improvers to aid its measurement and performance is necessitated. This article presented two phase liquid – solid lubricants of PTFE and MoS2 solution in SAE 30 oil at varying compositions. The lubricants tested are SAE #30, SAE #30 plus PTFE and SAE #30 plus MoS2. High-pressure viscosity measurement was done at pressure up to 1.5 GPa and temperature range at 20°C to 100°C. Viscosity indices are calculated from the measured viscosity at 40 and 100 ºC using ASTM D 2270. However, an attempt to predict α for the blended lubricants using the relationship between pressure-viscosity coefficient and Walther’s logarithm of kinematic viscosity at atmospheric pressure was used. The pressure-viscosity coefficient of two phase liquid – solid lubricants were successfully predicted and the influence of solid lubricant concentration, and temperature on the lubricants viscosity were determined, and compared with SAE #30 oil. The properties and viscosity of mixtures obtained are optimal lubricant factors which optimze the measurement and performance of the highest EHL pressure-viscosity coefficient of the mixtures, and also enhance the better chance to improve the lubrication of machine element than the SAE #30 conventional engine oil.
Determining the level of knowledge of lean production techniques in newspaper firms in Ghana.
(International Journal of Engineering Research & Technology (IJERT), 2016) Govi, D.K.; Amoakoh, C. N.; Goddey, P.G.
Many people, especially the youth, are also turning to the internet for news at the expense of Newspapers. Financial viability for newspapers, at least for now, requires retaining as many existing print readers as possible. However, as trend for Newspaper circulation shows a continuous decline over the past decade, publishers need to ensure that production waste is reduced to the barest minimum to keep costs down so as to remain afloat. The newspaper business has trived on high advertising revenue for decades until now that they are confronted with the Internet and new media. The study will critically examine the existing production system, including systematic work flow and ascertain the possibilities to identify and eliminate the perceived waste in the production chain. This critical assessment will be carry out using appropriate statistical tool to reveal the consequential impacts of such waste in the production system.
A review of water charges: customers’ perception of the quality of the levels of service in Ghana, the water charges and their willingness to pay for improved services.
(Journal of Research in Humanities and Social Science, 2016) Gyabaah, F.; Amankwah-Minkah, A.; Agbotui, P. Y.
The trade-off between full cost recovery and providing the urban poor with potable water in the right quantity, quality and at affordable prices is ever increasing especially in African countries. Ghana, not being an exception continues to struggle in its efforts to provide safe drinking water to the urban populace and Ghana Water Company Limited (GWCL), the urban water service provider stands at the centre of this ordeal. The company has been criticised for being inefficient in its management of the urban water supply due to various reasons - technical, financial and political. This report reviews the water supply management in Ghana. It further investigates by way of a survey, the perception of consumers in Ghana of the quality of the levels of service offered them regarding water quality, quantity and reliability, as well as the affordability and willingness to pay for improvements in the water services rendered by the GWCL. The survey came up with one hundred and thirty-four (134) valid respondents – 56 directly handed out printed questionnaire respondents and 78 online respondents. The survey results show that most customers perceive the water quality and reliability of the service received as being average and above, although over 78% of them have their water supply interrupted at least once every week. The quantity of water received is shown as not being adequate, since 54% of customers resort to other sources of water to supplement public supply. Even though the water quality is rated as good, customers rarely drink water from this service, as 66.4% of them prefer drinking sachet or bottled water. Most consumers (63.4%) think the current water prices are high and only about 3% are willing to pay more to achieve full cost of water service and for a significant improvement to the supply system. The water supply situation in Ghana should be recognized as a national issue and given higher priority. Major reforms need to be made in both policy and practice if the levels of service are to match up to internationally accepted standards. This would bring significant public health improvements and service improvements to wider Ghanaian society
Performance analysis of particle swarm optimization approach for optimizing electricity cost from a hybrid solar, wind and hydropower plant
(International Journal of Renewable Energy Research (IJRER), 2016) Acakpovi, A.
This paper deals with the cost optimization of a hybrid solar, wind and hydropower plant using a Particle Swarm Optimization (PSO) approach. PSO is a technique that belongs to Swarm intelligence, an artificial intelligence (AI) technique, known as a Meta-heuristic optimization solver, mostly used in Biology. With the consideration of solar, wind and hydro hybrid system which has become extremely relevant for developing countries, and also the existence of a wide list of constraints, the adoption of PSO technique cannot be avoided. On the other hand, a linear optimization approach was used with Matlab software to solve the same problem. Both techniques were applied to secondary data collected from RetScreen Plus software for the location Accra and results were extracted in terms of distribution of supply by individual sources and cost of hybrid system electricity. Results show in general, an improvement of hybrid system cost of electricity. A histogram was used to show the distribution of supply for the particular load and the equivalent cost of hybrid system that corresponds to it. A khi-sqaure test was run to compare the two series of data obtained from the two approaches adopted. The Khi-square test show high similarity confirming the reliability of the PSO approach which on the other hand presents the advantage of scalability over a wider range of sources with multiple constraints.
Numerical analyses of transient flow characteristics within each nozzle hole of an asymmetric diesel injector.
(International Journal of Heat and Mass Transfer, 2017) Xue, F.; Luo, F.; Cui, H.; Adams, M.; Zhou, L
In order to simultaneously study the differences in transient flow characteristics within each nozzle hole of an asymmetric multi-hole diesel injector used in off-road machinery, a three-dimensional gas–liquid two-phase flow model of cavitation was developed, which takes the influence of injection conditions and bubble number density into consideration. The computational model was validated by comparing it with the experiment conducted by Winklhofer. The result shows high level of consistency and sensitivity. Following the successful verification of the model, the differences in transient flow characteristics within each nozzle hole based on a P-type asymmetric multi-hole nozzle with sac were analyzed using the model. Results obtained from simulation shows that the cavitation phenomenon, velocity profile and mass flow rate in each nozzle hole of an asymmetric injector differ greatly. The hole with the higher nozzle hole angle (wider angle between nozzle hole axis and needle axis) was more inclined to cavitate, therefore the cavitation effect intensity is directly related to the size of the nozzle hole angle. During the lifting stages of the needle valve, the cavitation effect for each nozzle hole and the fuel flow velocity are gradually enhanced while on the contrary, the fuel flow velocity decreases and cavitation effect slightly increases at the closing stages of the needle valve lift. Also, the cavitation morphology at the same needle valve lift in any nozzle hole differs during opening and closing stages of fuel injection. In addition, the fuel flow velocity profile from the needle valve opening at the sac and into the hole of each nozzle shows that, in the order of increasing nozzle hole angle βi, the velocity effect gradually reduces as a result of dramatic change in flow direction.
The enhancement of fracture toughness and tribological properties of the titanium nitride films by doping yttrium.
(Surface and Coatings Technology, 2017) Ju, H.; Yu, L.; He, S.; Asempah, I.; Xu, J.; Hou, Y.
In this paper, yttrium was incorporated into titanium nitride matrix to deposit Tisingle bondYsingle bondOsingle bondN films using a reactive magnetron sputtering system and the microstructure, mechanical and tribological properties were investigated. The results showed that solid solution face centered cubic (fcc) Tisingle bondYsingle bondN was the major phase of the film when the yttrium content was < 7.8 at.%. When the yttrium content was further increased, the film exhibited mixed phases of fcc-Tisingle bondYsingle bondN and amorphous yttrium oxide, this induced grain refinement and appearance of lots of grain boundaries. Hardness of the films first rose from 21 GPa at 0 at.% Y to 26 GPa at 10.2 at.% Y, and remained stable as the yttrium content was above 10.2 at.%. The hardness was influenced by the amorphous yttrium oxide phase, solid solution strengthening, grain boundaries and residual stress. Between 0 at.% to 7.8 at.% of yttrium, the fracture toughness (KIC) rose slowly, KIC rose sharply to 0.85 MPa.m1/2 as the yttrium content was 10.2 at.% due to the formation of amorphous yttrium oxide phase, it rose slowly again with a further increase in yttrium content. For the film at < 7.8 at.% Y, average friction coefficient (μ) and wear rate were influenced by the load significantly and there was an obvious rise in their values with an increase in load. A further increase in yttrium content in the films, improved the tribological properties, μ and wear rate were almost independent on the load. Fracture toughness enhancement attributed to the improved load capacity and tribological properties.
Comparative study of flow characteristics within asymmetric multi hole VCO and SAC nozzles.
(Conversion and Management, 2017) Adams, M.; Zhou, Q.; Xue, F.; Luo, F.
A three-dimension model of an asymmetric valve covered orifice (VCO) nozzle and an asymmetric blind hole nozzle (SAC) used in two valve engines were developed for investigating in-orifice flow characteristics. Two fluid model approach used for turbulence and cavitation modeling was used to replicate the turbulence and cavitation phenomenon within the nozzles. The formation and the subsequent development of cavitation phenomenon was comparatively more prevalent in the VCO nozzle orifices. Cavitation development intensity was observed to be more significantly influenced by orifice inclination angles in the VCO nozzle as compared to the SAC. Although in-orifice flow velocity of VCO are higher under cavitating condition, their corresponding injection rates are lower comparatively, due to the formation of smaller effective flow areas in the orifices. However under non-cavitating condition, the in-orifice flow velocities and effective injection velocities from the SAC orifices are higher, relative to that from the VCO. The cavitation phenomenal distribution within the SAC orifices were at the top areas while that of the VCO were mostly at the mid-sections of the orifices. Increasing orifice inclination angle increases the degree of cavitation phenomenon but decreases the uniformity of in-orifice flow velocity in the nozzles. The rate of non-uniformity in orifice flow velocity distribution is much higher within the VCO orifices as compared to the orifices in the SAC. With a comprehensive insight of in-orifice nozzle flow characteristics for asymmetric nozzles, the combustion efficiency and the rate of soot formation in a two valve engine can be managed and improve significantly by manufacturers.
Quantitative studies of electric field intensity on atom diffusion of Cu/Ta/Si stacks during annealing
(Applied Surface Science, 2017) Wang, L.; Asempah, I.; Dong, S. T.; Yin, P. P.; Jin, L.
It has been shown that enhanced electric field intensity (0–4.0 kV/cm) has an obvious effect on accelerating atom diffusion in Cu/Ta/Si interconnect stacks at 650 °C. The theoretical deduction proves that diffusion coefficient is accelerated proportional to an acceleration factor (1 + a·αE/0.8)2. The analysis indicates that the accelerating effect is mainly attributed to the perturbation of the electric state of the defects and enhanced vacancy and dislocation densities.
Highly sensitive and label-free determination of thiram residue using surface-enhanced raman spectroscopy (SERS) coupled with paper-based microfluidics.
(Analytical Methods, 2017) Zhu, J.; Chen, Q.; Kutsanedzie, F. Y.; Yang, M.; Ouyang, Q.; Jiang, H.
In this study, a paper-based microfluidic surface-enhanced Raman spectroscopy (SERS) device was employed for the determination of trace level thiram. The paper-based microfluidic device was fabricated by cutting a hydrophilic region which had been printed on the filter paper and then pasting it onto sellotape. The Au@Ag nanoparticles (NPs) were synthesized with a 30 nm Au core and 7 nm Ag shell and used as the SERS probe. The synthesized nanoparticles were dropped in one of the sample adding zones of the paper-based microfluidics and the thiram solution was dropped in another one. The solutions flowed through their own channels by capillary action and mixed together in the reaction chamber. The optimization studies on the use of paper-based microfluidic devices are discussed. In SERS measurements, the intensity of the peak at 1143 cm−1 was highly sensitive, and so it was chosen as an ideal peak for the quantitative analysis of the concentration of thiram solution. The limit of detection (LOD) of thiram was as low as 1.0 × 10−9 mol L−1, and the relative standard deviation (RSD) results analyzed at 10 random spots in the SERS measurement area were all below 10%. The recovery values of thiram in adulterated tea samples were from 95% to 110%. All these results suggest that this proposed method is a prospective candidate for trace level thiram detection.

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