School of Engineering
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Item Adaptive Hybrid Collaborative Filtering Recommendation System (AHCF)(University of Ghana, 2019-07) Agboyi, R.Recommendation systems play a vital role in boosting the organization’s profit, especially for e-commerce platforms such as Amazon. These systems focus on targeting specific products to users and predicting user preferences and interests. However, recommendation systems are plagued with many challenges, such as adapting them to changes in user preferences and taste, and the effectiveness of recommendations made also determines the ability to retain and engage new users, as new user conversion to clients. This thesis proposes to use an adaptive hybrid collaborative approach to making recommendations to users. Four algorithms are combined: the Alternate Least Squares (ALS), KMeans clustering, Latent Dirichlet Allocation (LDA) and KMeans streaming. The recommender engine developed is in itself a multi-hybrid system as it not only combines four (4) algorithms but also combines the collaborative technique and content-based techniques of making a recommendation. Thus, the approach adopted can be used on datasets that contain rating information, textual descriptions or both. Three servers are leveraged in the implementation, consisting of the Scala server, PHP and Angular JS server and the MySQL database server for the storage of the results from the recommender engine. Various industry-standard metrics are adopted for the individual algorithms in addition to their computational times. These metrics include Root Mean Square Error(RMSE) for the ALS, Within Cluster Sum of Squares(WCSS) for KMeans, Log Perplexity and Log-Likelihood in the LDA. The memory estimates footprints and computational time on retraining the model are recorded for the KMeans streaming. The recommender engine is tested primarily on the 100K and 1M movieLens datasets and some portions of the 20M dataset are used. The implementation is compared with benchmark recommender algorithms via GitHub and existing offline implementations. In terms of retraining, the Adaptive Hybrid Collaborative Filtering Recommendation System(AHCF) developed improves a recommendation’s computational time concerning the offline model by 50%. The AHCF has an accuracy measure of 0.88-3.0 on RMSE values for the chosen datasets on increasing rank but less than 8 for 5 other datasets adopted. The other datasets range from restaurant datasets, anime, dating datasets, books and e-commerce. These results are taken for the 1M and 100K datasets. The unique contributions made in this research include combining multiple algorithms into one recommender engine that leverages textual and rating information at the same time. Improvements in computational efficiency as against offline models that are designed for a real-time update of recommendations by half on retraining. The generic nature of the algorithm also makes it useful to be used in many domains that leverage informative text and rating information. The model is also open source and available to all users. In a nutshell, the research embraces the efficiency of updating user preferences in real-time and making personalized recommendations by adapting to user preferences over short time intervals.Item Biosynthesis of Magnetic Iron Oxide Nanoparticles and Its Potential Application in Cancer Treatment.(University of Ghana, 2018-07) Amartey, N.A.Cancer is one of the leading causes of death globally and its treatment and cure are therefore very important. Chemotherapy, radiation, and surgery have been the major forms of treatment. In this work, magnetic Fe3O4 nanoparticles are biologically synthesized using maize leaves, plantain leaves and peels extracts as mediators. The synthesized particles were magnetic and this aided in their washing after the synthesis. UV-Vis spectroscopy pointed to the formation of the Fe3O4 nanoparticles as the absorption wavelength range of 300-800 nm was recorded. EDX data obtained showed the presence of Fe and O, depicting the presence of iron oxide in the sample. The EDX data also showed the presence of other elements such as Ca and K which were considered an evidence of the complexity of the plant extracts employed in the synthesis. FTIR analysis was conducted for both the plants used and the particles synthesized. The spectra, which was between ~3500 – ~450 cm-1, pointed to the presence of phenol compounds and proteins in the plant extracts that contributed to the formation of the magnetic Fe3O4 nanoparticles. It also showed the presence of Fe-O bonds at a wavenumber of 544 cm-1. SEM images obtained showed varying levels of agglomeration in particles formed. The particles were used on Hela cell and recorded a reduction in cell viability. The particles were responsible for a reduction of the cell viability (50.41- 60.82).Item Buoyant Gaussian Plume Modeling of atmospheric Dispersion of Cs-137 Emitted from a Nuclear Reactor(University of Ghana, 2013-07) Djangmah, J.A.A two dimensional Advection-Diffusion equation was developed to model atmospheric dispersion of Cs-137 in order to visualize the phenomenon of the transport ofCs-137 in the atmosphere. The study was also aimed at analyzing the activity concentration of Cs-137 and examined the mathematical approaches for determining the mass concentration of Cs-137 released to the atmosphere. The Buoyant Gaussian model was examined and a finite difference scheme was developed to solve the partial differential equations of radionuclide pollution transport in the atmosphere. The model program code for Gaussian Plume was implemented by using the MATLAB interface contouring software. The result outputs showed that like other parameters, depth has significant influence on the dispersion of pollutants; the highest and least activity concentrations of Cs-137 dispersion were found to be 0.4686 𝑚𝑔/𝑚3and 0.0002 𝑚𝑔/𝑚3 at 2.5 𝑚/𝑠 respectively. The maximum distance that was covered by Cesium-137 from the source downwind was 1621m at 5m/s. In the event of an accidental atmospheric release of radionuclides from a nuclear power plant, accurate forecasting of the dispersion and the activity concentrations of radionuclides are required for the preparation of adequate countermeasures and evacuation.Item A Comparative Study of Phosgene Sensing Using Carbon and Boron Nitride Nano Materials – A DFT Approach(University of Ghana, 2021-04) Kweitsu, E.O.Phosgene (COCl2), a valuable industrial compound, maybe a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of simple and highly sensitive techniques that overcome these challenges. Recent advances in nanomaterials science offer the opportunity for the development of such techniques by exploiting the unique properties of the nanostructures. In this study, we investigated the potential of six types of nanomaterials: three carbon-based ([5,0] CNT, C60, C70) and three boron nitride-based (BNNT, BN60, BN70) for the detection of COCl2. The local density approximation (LDA) approach of the density functional theory (DFT) was used to estimate the adsorption characteristics and conductivities of these materials. The results show that the COCl2 molecule adsorbed spontaneously on the Fullerene or nanocages and endothermically on the pristine zigzag nanotubes. Using the magnitude of the bandgap modulation, the order of suitability of the different nanomaterials was established as follows: PBN60 (0.19%) < PC70 (1.39%) < PC60 (1.77%) < PBNNT (27.64%) < PCNT (65.29%) < PBN70 (134.12%). Since the desired criterion for the design of an electronic device is increased conductivity after adsorption due to the resulting low power consumption, PC60 was found most suitable because of its power consumption as it had the largest decrease of 1.77% of the bandgap.Item Computer–Aided Approaches To Discovery Of Novel Drugs Against The Human Hookworm Necator Americanus (Nematoda: Ancylostomatidae)(University of Ghana, 2017-07) Agyapong, O.There is a crucial need to develop novel anthelminthic drugs due to the mounting disease burden and increasing evidence of hookworm resistance to drugs such as albendazole and mebendazole, which for decades have been used to treat the infection. Consequently, it is exigent to develop alternative drugs with improved therapeutic efficacy. Natural products due to their unique active ingredients have been shown to possess exceptional structures with chemical diversity that is unmatched by any synthetic libraries. It is imperative to leverage natural products to augment hookworm drug discovery. Therefore, this study aimed to: (i) identify potential novel anthelminthic lead compounds by screening African natural product-derived ligands against beta tubulin of Necator americanus, a known hookworm receptor and (ii) develop support vector machine-based proteochemometric modelling (PCM) for bioactivity profiling of beta tubulins receptors. The 3D structure of the beta tubulin of hookworm with UniProt entry W2T758, was generated using homology modelling. The model was subjected to molecular dynamics simulations and active site interactions prediction. The first set of ligand libraries comprising 885 natural product compounds obtained from African medicinal plants database (AfroDb) combined with Dichapetalin A, were screened against the receptor. ZINC14760755 and ZINC28462577 compounds were found to be potential leads due to promising binding affinity, active site interactions and pharmacokinetic profiles. Additionally, a second set comprising 2297 compounds derived from Northern African Natural Product Database (NANPDB) were virtually screened. The compound S,5Z,8Z,11Z,13E,17Z-15-hydroxy-1-(2,4,6-trihydroxyphenyl)-15-methylicosa-5,8,11,13,17-pentaen-1-one exhibited plausible binding affinity, toxicity and pharmacokinetic profile. The aforementioned natural compounds are potential leads which can be experimentally characterised for possible pre-clinical trials. Support vector machine based proteochemometric modelling was also developed to predict the bioactivity relations between beta tubulin variants and small compounds using an interaction dataset retrieved from BindingDB. The model achieved reasonably good performance with a ROC-AUC of 87%, an MCC of 0.75 and a classification error of approximately 4%, although it was trained on a small dataset. The model allows the prediction of the likelihood of interactions between query datasets comprising ligands in SMILES format and protein sequences of beta tubulin targets. In future, larger bioactive datasets of beta tubulins originating from high throughput experiments can be utilised to possibly enhance the performance of the hookworm PCM model.Item Corrosion Inhibitors from Plant Extract and Terephthal Amide Derived From Waste Pet Bottles for Mild Steel in Acidic Medium(University of Ghana, 2018-12) Arday, N.A.Powdered Cassia Siamea leaves were investigated as a possible corrosion inhibitor for mild steel in 2 M HCl. Terephthal amide obtained from depolymerizing waste PET (Polyethylene terephthalate) bottles through aminolysis using mono ethanol amine (MEA), served as an additive to improve the efficiency of the powdered leaves. The plant inhibitor was prepared by dissolving 1.5 g of the powdered leaves in 300 ml of 2 M HCl and boiled for 3 hours. Corrosion rates of the steel samples were determined using both electrochemical analysis and weight loss measurements. The powdered leaves and terephthal amide were characterized using Fourier Transform Infrared Spectroscopy (FTIR). Phytochemical screening was conducted on the powdered leaves to verify the presence of heterocyclic compounds such as tannins and flavonoids since they are known to have inhibitive properties. Results obtained from electrochemical readings show a reduction in corrosion rate (CR) with increasing plant inhibitor volume concentrations. The CRs decreased even further with the addition of the terephthal amide thereby increasing the inhibitor efficiency (IE %) of the plant inhibitor. It was observed from the polarization curves that the cathodic reactions were inhibited more as compared to the anodic reactions and therefore the inhibitor can be classified as a cathodic inhibitor. The CRs obtained from weight loss measurements also show a reduction in rates with increasing concentration, corresponding to the electrochemical readings. Less weight was also lost with increasing inhibitor concentration. The phytochemical screening confirmed the presence of tannins, saponins and flavonoids in the powdered leaves. The FTIR also confirmed the presence of heterocyclic compounds and amides in the powdered leaves and terephthal amide respectively.Item Decision Support System For Sizing Drying Bins, Fan Selection And Drying Parameters Determination For Selected Grains(University Of Ghana, 2022-01) Parker – Allotey, C.K.Grain drying is a very important step in the storage and handling of grains. Computer models have been created over the past years to optimise and ease the amount of work and calculations that are invested into the planning, economics building, operation and management of drying systems and facilities. Although there have been advancements in computerised systems and programmes, decision making when it comes to planning, costing, construction, management, and operation of drying systems can still prove to be a strenuous task to undertake. Also, most computerised systems require in-depth knowledge in drying to operate. Most of these systems do not also provide features which allow for economic decision making. There is therefore still the need to develop a new programme which is relatively easier to use and can further optimise the decision-making process. A computer programme was developed using python that calculates the bin diameter, grain depth, airflow and airflow rate, and fan horsepower using the specific grain to be dried, the desired volume, drying method, and budget type as inputs. Various formulas and assumptions were used to perform calculations for each parameter. The programme was created to provide realistic estimates for each drying parameter depending on the inputs provided by the user. The programme also provides a database that allows users to select fans based on the calculated fan horsepower. The programme created was successful in performing calculations for all the parameters listed above. This programme simplified certain calculations that must be made during the decision-making process, thereby allowing for its use by people with shallow knowledge in drying systems decision making with respect to budgeting.Item Decision Support System For Sustainable Siting And Management Of National Food Buffet Stock Systems In Ghana(University Of Ghana, 2022-02) Buah, I.E.National Food Buffer Stock Company of Ghana (NAFCO), being the government’s emergency food reserve and source of raw materials for agro-processing factories, is established to reduce post-harvest losses, and stabilize food supply and price. These stated aims are very broad, conflicting, and non-profit-oriented, making the buffer stock systems economically unsustainable. This research, therefore, develops a decision support system where decision-makers can stimulate various scenarios to allow them to design a sustainable national food buffer stock system that is fit for its purpose. The decision support system comprises a risk assessment conducted on the operations of NAFCO, pseudo-p-median model, goal programming model and inventory model. The efficacy of the decision support system was illustrated through a series of simulations, where six predicted optimal locations for siting NAFCO warehouses were identified with an average transportation cost of GHS 1.7924E+6. The optimal network design of NAFCO warehouses was to reduce the cost of transportation incurred by the respective stakeholders. The research also investigated the number of grains to be purchased during every quarter, if NAFCO was to stock their warehouses with 100,000 tonnes of grain in the year to reduce the cost of operation. An integrated approach coupled with readily available data was used in stimulating the models developed. Furthermore, the research provides NAFCO with the necessary actions to take to reduce the risk associated with the unit operation of transporting grains from the farm to the warehouses and from the warehouses to the markets and harbour since this operation had a risk profile number of 648. In conclusion, decisions must be taken to revamp the operations of NAFCO with the mindset of reducing cost by adopting decision support systems in sustainably siting and managing their operations.Item Design and Development of Power Distribution Network Fault Data Collection Device, Fault Detection, Location and Classification Using Machine Learning Algorithms(University of Ghana, 2016-07) Dzabeng, N.A; Sowah, R.A; University of Ghana, College of Basic and Applied Sciences, School of Engineering, Department of Computer EngineeringThe detection and location of faults on power transmission lines is essential to the protection and maintenance of a power system. Most methods of fault detection and location rely on measurements of electrical quantities provided by current and voltage transformers. In this work, current sensors and voltage sensors were used in the prototyped model of the data collection device. Training data were collected by taking into consideration variables of a simulation situation like fault type, sensor location on the node, short circuit and open circuit faults were also analyzed. The test data were analyzed using three machine learning classifiers namely: K- Nearest Neighbor (KNN), Decision Tree and Support Vector Machines (SVM). Simulation result indicates that the anticipated method for fault classification gives high accuracy (99.5%) and least fault distance estimation error (0.5%) for all discussed cases. In order to verify the accuracy of the proposed method, a comparison is carried out with decision tree (DT), KNN and SVM. Separate investigation was also carried out with testing the system by varying the load at the range of 0%- 100%. It is observed from the test results of the network model that, the fault detection, location and classification gives a high accuracy with machine learning decision tree giving a quick training time response of 0.000999928 seconds.Item Design and Fabrication of a Control System for a Photovoltaic-Greenhouse Solar Dryer and Performance Evaluation of the Dryer(University of Ghana, 2019-07) Afenyie-Abekah, M.Solar dryers have become important components for the delivery of dried agricultural products of high quality. They generally are designed to maximize the production of a heating system based on solar radiation. This study involved the design, building and testing of a control system to allow the monitoring of temperature, solar radiations and control of humidity in a Photovoltaic (PV)-Greenhouse Solar Dryer (PVGSD). This was accomplished by assembling a solar charge controller, three solar panels, a power inverter, and a battery system. An Arduino UNO Rev3, DHT22-sensor, solderless breadboard, Liquid Crystal Display (LCD) screen, jumper cables, Light-Emitting Diode (LED) red, Global System for Mobile (GSM) communication module, 10k Ω, 220 Ω and 1k Ω resistors and two 5V one channel relays formed the control system. These were assembled in a multi-functional workstation linked to the solar dryer. The GSM communication module was an innovation to allow connection to the internet over General Packet Radio Service (GPRS) network and send/receive SMS. It was used to control the fans remotely and further allowed logging of periodic sensor data (temperature, humidity, voltage and solar radiation values) by sending SMS to a phone number and server. Dryer and product characteristics were measured including temperature, humidity, solar radiation and moisture content. The temperature and humidity profile were monitored for 11 days in the empty PVGSD without the workstation and Open Sun Drying (OSD) showed that the PVGSD recorded the highest temperature of 69oC occurring between 12:00 and 14:00 hours GMT while the OSD recorded at 41.5oC. The highest relative humidity recorded in the PVGSD was 75.5% and 83% for OSD observed at night from 20:00 hours to 5:00 hours GMT. Two commodities, cassava (slices and chunks) and red pepper were dried to evaluate the dryer efficiency, and this was compared with OSD and existing greenhouse type solar dryer (GSD). The cassava slices dried faster than the cassava chunks in all the drying methods indicating that sample size influenced drying rate. PVGSD had a faster drying rate for cassava slices of 0.0732g/g.h compared to 0.04908g/g.h for GSD and 0.02074g/g.h for OSD, while drying rate of PVGSD, GSD and OSD for cassava chunks were 0.0457g/g.h, 0.0355g/g.h and 0.01667g/g.h respectively. Similarly, PVGSD was observed to obtain the highest rate of drying for red pepper of 0.097g/g.h compared to GSD of 0.094g/g.h and OSD of 0.047g/g.h. The drying method, time and sample size were found to have statistical significance (p<0.05) on temperature, moisture content, humidity and drying rate. The PVGSD dryer with the workstation was able to keep the humidity conditions in the dryer low to prevent moisture uptake during the night. The samples in this dryer showed consistent drop in moisture content throughout the drying period. To further evaluate the drying effect on the samples, laboratory analyses such as water activity, color profile and particle size determination were performed on the resultant dried cassava flour samples and red pepper (whole). The color profile of red pepper flour and cassava flour from the PVGSD was observed to be better in terms of the redness (a*) for red pepper, lightness (L*) for cassava, browning index (BI) and color change (ΔE). The color change of red pepper for PVGSD, GSD and OSD were 11.94, 16.43 and 25.25 respectively. The color change of cassava slices for PVGSD, GSD and OSD were 10.49, 10.84 and 11.59 respectively, while that for cassava chunks recorded at 10.60, 12.09 and 12.11 respectively for PVGSD, GSD and OSD. The SD50 values for flours from the slices were finer than those from the chunks. The SD50 values for cassava slices under PVGSD, GSD and OSD were 62 μm, 76 μm and 78 μm respectively, while SD50 values for cassava chunks under PVGSD, GSD and OSD recorded at 80 μm, 92 μm and 106 μm respectively. In general, cassava slices under the three drying methods demonstrated a better quality than the chunks in terms of color and particle size. All samples were dried to a water activity below 0.500 to prevent microbial spoilage. Final water activity for red pepper was 0.384, 0.388 and 0.414 respectively for PVGSD, GSD and OSD, while that for cassava slices and chunk for PVGSD was 0.361 and 0.415 respectively, GSD was 0.384 and 0.446 respectively and OSD recorded at 0.421 and 0.490 respectively. To further understand and describe the drying curves for the samples under the three drying methods, 12 Thin Layer Mathematical models were evaluated. The best model under this study for red pepper is the Midilli and Kucuk model under both PVGSD and GSD while Logarithmic model describes best under OSD. Approximation of diffusion model can be used for cassava slices under PVGSD and GSD, while Midilli and Kucuk model for OSD. These models were selected according to the lowest Root Mean Square Error (RMSE) and chi square (χ2) and highest correlation coefficient (R2).Item Design and Fabrication of a Sustainable Construction Brick(University Of Ghana, 2019-07) Asante, E.The urgent need for affordable housing is driving the research for cheap and sustainable building materials. The nuisance caused by cocoa pod husks, which is an agro waste, could be curbed by the incorporation of potash derived from its ash into brick batch mix. These potash incorporated bricks tend to allow sintering at lower temperatures thus reducing production cost and hence making them cheaper. In this project, the SiO2 – Al2O3 – K2O ternary phase diagram was used to design three compositions for brick batches. Briquette samples for both compositionally designed batches and control batches were fabricated and fired. Hydration and water absorption tests were undertaken for the various samples to ascertain durability and response to moisture. Brick samples were also fabricated and fired at 500 °C and 600 °C respectively, with their water absorptivity and compressive strengths measured. The compressive and water absorption test results were higher for 500 °C than at 600 °C due to the black core effect.Item Determination Of Engineering Properties Of Two Soils At Fohrec (Kade) And Sirec (Kpong)(University of Ghana, 2019-07) Danso-Acquah, E.Agriculture, its operations, and soils properties are inter-related. Cultivation of crops; tillage, irrigation and farm operations, commuting to and from farm plot and building of structures are greatly influenced by the soil specifically its properties. Shear stress, cohesion and angle of friction are parameters that play major roles in influencing how soils are used or worked on. It is, therefore, important to determine the shear stress, cohesion and angle of friction of the soils in Kade and Kpong. As a result, a study was conducted on two soils from Forest and Horticulture Research Centre (FOHREC), Kade, and Soil and Irrigation Research Centre (SIREC), Kpong, at depth ranges of 0-15cm and 15-30cm under saturated and unsaturated conditions to determine the shear stress, cohesion and angle of friction to ascertain how they will affect tillage, traction and trafficability, irrigation and structures such as dams and foundations. Normal stress ranging from 1kg/cm2 to 5kg/cm2 was used as an independent variable to determine the stated properties. The results showed that the Kpong soil had a higher shear stress under all conditions than that of Kade soil. An interesting observation was made concerning the soil under unsaturated condition where at 3kg/cm2 it behaved as if it is is under saturation. The normal stress had a significant effect (p < 0.05) on shear stress, cohesion and angle of friction, where increase in normal stress reflected an increase in shear stress and cohesion but a decrease in angle of friction. The research provided ample data on shear stress required for failure to occur normal to the shear plane, cohesion and coefficient of internal friction. These measurements are relevant and important for the design of farm equipment, farm structures such as dam wall, storage buildings, etc. Kpong soil (Akuse series) had a higher shear stress under all conditions than that of the Kade soil (Kokofu series). Keywords: Shear Strength, Cohesion, Angle of friction, Trafficability, Tillage, Moisture contentItem Determination of Engineering Properties of two Soils at FOHREC (KADE) and SIREC (KPONG)(University of Ghana, 2019-07) Danso-Acquah, E.Agriculture, its operations, and soils properties are inter-related. Cultivation of crops; tillage, irrigation and farm operations, commuting to and from farm plot and building of structures are greatly influenced by the soil specifically its properties. Shear stress, cohesion and angle of friction are parameters that play major roles in influencing how soils are used or worked on. It is, therefore, important to determine the shear stress, cohesion and angle of friction of the soils in Kade and Kpong. As a result, a study was conducted on two soils from Forest and Horticulture Research Centre (FOHREC), Kade, and Soil and Irrigation Research Centre (SIREC), Kpong, at depth ranges of 0-15cm and 15-30cm under saturated and unsaturated conditions to determine the shear stress, cohesion and angle of friction to ascertain how they will affect tillage, traction and trafficability, irrigation and structures such as dams and foundations. Normal stress ranging from 1kg/cm2 to 5kg/cm2 was used as an independent variable to determine the stated properties. The results showed that the Kpong soil had a higher shear stress under all conditions than that of Kade soil. An interesting observation was made concerning the soil under unsaturated condition where at 3kg/cm2 it behaved as if it is is under saturation. The normal stress had a significant effect (p < 0.05) on shear stress, cohesion and angle of friction, where increase in normal stress reflected an increase in shear stress and cohesion but a decrease in angle of friction. The research provided ample data on shear stress required for failure to occur normal to the shear plane, cohesion and coefficient of internal friction. These measurements are relevant and important for the design of farm equipment, farm structures such as dam wall, storage buildings, etc. Kpong soil (Akuse series) had a higher shear stress under all conditions than that of the Kade soil (Kokofu series).Item Effect of Biochar on Soil Physical Properties, Water Use Efficiency, and Growth of Maize in a Sandy Loam Soil(University of Ghana, 2016-06) Monnie, F.; Mickson, S.A.; University of Ghana, College of Basic and Applied Sciences School of Engineering Department of Agricultural EngineeringThere has been claims that biochar improves water retention in soil and aid in improved crop productivity. Hence, recent conservation practices in the area of agricultural lands have focused research attention on the performance mechanism of biochar. In this study, the effect of corn cob biochar particle sizes (<2 mm & ~2-4 mm) and amounts (0, 20, 40, 80 tons/ha) on soil physical properties (soil bulk density and soil water retention) and biomass yield were investigated. It further investigated the effect of deficit (DI) and full (FI) irrigation in combination with biochar on plant physiology and water use efficiency. Corn cob biochar was mixed with the top 20 cm sandy loam soil at a rate of (0, 20, 40 & 80 tons/ha) in pots made of PVC columns (20 cm diameter x 75 cm height). Three maize seeds were planted and thinned out two weeks after planting leaving one maize plant per pot. NPK fertilizer (3.1 g) was applied to all pots. Soil moisture content reading was taken every third day for the first three weeks and every second day afterwards. From the beginning, each pot was supplied with the amount of water lost to restore to field capacity. After three weeks, deficit irrigation (DI) strategy was implement. All full irrigation (FI) treatments were irrigated immediately water loss exceeded a management allowable depletion (MAD) of 30 % of the pot field capacity, and for the DI treatments at MAD of 80 %. Three drying cycles were achieved between day 26 and day 70 (last day of terminating the work). The results showed that bulk density (BD) decreased significantly between the control (1.46 g/cm3) and the 80 tons/ha (1.30 g/cm3) biochar treatment. Also, BD decreased insignificantly with decreasing biochar particle sizes relative to the control. BD was found to decrease with increasing biochar fine i.e. (CBP (2- 4 mm)> FBP (<2 mm)). Bulk densities of 1.39 g/cm3 and 1.35 g/cm3 were found for the coarse biochar particle (CBP) and fine biochar particle (FBP) respectively relative to the control 1.46 g/cm3. Soil water retention characteristics were affected by addition of biochar. The result shows that addition of 20 tons/ha biochar surprisingly did not alter the curve that much though at higher matric potential tends to hold substantial amount of water relative to the no biochar treatment. However, biochar application rate of 80 tons/ha had significant effect relative to the control. It was discovered in general that, applying corn stover biochar at a rate beyond 20 tons/ha will improve the water retention characteristic of sandy loam soil. Furthermore, biochar particle size also affected the water retention characteristics as it was discovered that, the FBP retained more water at low matric potential but as matric potential increased beyond -300 kPa, the CBP retained more water. Furthermore, the biomass yield (BY) results showed a yield loss of 21.2% for DI treatments relative to the FI treatments. However, 59.2% water was conserved in this case for the DI treatments. This implies biochar addition to soil with deficit irrigation practices may be a promising water conservation strategy. It was also observed that, the yield values for the DI biochar treatments were close to the FI control values. Transpiration efficiency was significant between the DI treatments (32 g/mm) and the FI treatments (20 g/mm). Plant physiology was also enhanced by the addition of biochar even though the differences were not consistently significant. Therefore, it is concluded in this study that addition of corn cob biochar does improve soil physical properties and enhance water retention within the soil, and that biochar amendment in combination with deficit irrigation does have the potential to improve water use efficiency by enhancing plant physiology and yield.Item Effect Of Clay Pozzolana On The Corrosion Behaviour Of Steel Reinforcement In Concrete(University of Ghana, 2017-07) Mussey, B.K.This study investigated the corrosion resistance of steel reinforcement in two types of concrete mixtures – ordinary Portland (OPC) used for concrete and clay pozzolana cement (CPC) used for concrete. These two concrete types were exposed to 3% and 5% (W/V) of Sodium Chloride (NaCl) and 3% (W/V) Calcium Hypochlorite (Ca(OCl)2) that acted as corrosion media. Mechanical properties and electrochemical analysis were performed over 1, 7, 15 and 23 days. The results indicated that concrete mixtures that contained clay pozzolana cement recorded an average compressive strength of 15.17 MPa while that which contained ordinary Portland cement was 22.75 MPa. Pull – out forces recorded for steel embedded concrete samples that contained clay pozzolana cement in the corrosion media recorded average values of 71, 65.33, 57.7 and 54.67 MegaNewtons (MN) over 1, 7, 15 and 23 days respectively as compared to 80, 70.1, 61, and 49 MN over the same period for concretes without clay pozzolana. Values of corrosion rates obtained from anodic and cathodic curves from Tafel plots revealed that samples exposed to 5%(W/V) NaCl had higher corrosion rates followed by those exposed to 3%(W/V) NaCl and 3% Ca(OCl)2 in that order. XRD analysis showed high presence of Alite (3CaO.SiO2) in all concrete types, however concrete containing clay pozzolana, had higher amounts of alumina – silicates. The XRD also showed low intensity peak for sodium chloride (NaCl) in pozzolana containing concretes and relatively higher intensity peak for ordinary Portland cement (OPC) concretes. SEM showed shallow to deep corrosion pits on steel rods embedded in OPC containing concrete. No corrosion pits were found on steel rods embedded in CPC containing concretes, even though some surface corrosion activities were visible.Item Effect of Initial Land Preparation Methods on Selected Soil Physical Properties in Afram Plains, Ghana(University of Ghana, 2014-06) Quaye, D.N.D.; Abenney- Mickson, S.; University of Ghana, College of Basic and Applied Sciences, School of Engineering, Department of Agricultural EngineeringThe objective of the study was to determine the most appropriate methods of initial land preparations in Afram Plains based on their effect on selected soil physical properties such as dry bulk density, porosity, hydraulic conductivity and available water content. The study also sought to estimate the cost of preparing farm lands in the Afram Plains. The study was conducted in Odumesua in the Afram Plains District sampling soil from fields prepared with three identified and categorized systems of land preparations. These were Slash and Burnt cleared land with no-tillage (SBNT), manually cleared land with conventional tillage (MCT) and bulldozed land with conventional tillage (BCT). The soil properties were determined at 0-40cm depths at intervals of 10 cm for analysis. Financial cost of these land preparation methods was also estimated from machinery input cost derivatives and information gathered from local farmers. Dry bulk density, porosity and hydraulic conductivity were significantly (at p ≤ 0.005 level) affected by the land preparations methods. At different depths of sampling, hydraulic conductivity was not significantly (at p ≤ 0.005 level) affected. However, available water content was not significantly affected by both factors (land preparation methods and depth of sampling). Dry bulk density at 1.5g/cm3 reduced by 3% and 16% in MCT and BCT respectively compared with the UNCULTIVATED and SBNT. The results showed that agricultural lands prepared by bulldozing or stumps excavation and conventional tillage operations (BCT) was most appropriate using fertile agricultural soil indicators of soil physical properties. The results also indicated that it costs three times more in preparing lands employing heavy tractors like the bulldozer compared to the traditional methods of using human labour with simple toolsItem Effect of Initial Land Preparation Methods on Selected Soil Physical Properties in Afram Plains, Ghana(University of Ghana, 2014-06) Quaye, D.N.D.; Mahama, A.A.; Abenney-Mickson, S.; University of Ghana, College of Basic and Applied Sciences ,School of Engineering ,Department of Agricultural EngineeringThe objective of the study was to determine the most appropriate methods of initial land preparations in Afram Plains based on their effect on selected soil physical properties such as dry bulk density, porosity, hydraulic conductivity and available water content. The study also sought to estimate the cost of preparing farm lands in the Afram Plains. The study was conducted in Odumesua in the Afram Plains District sampling soil from fields prepared with three identified and categorized systems of land preparations. These were Slash and Burnt cleared land with no-tillage (SBNT), manually cleared land with conventional tillage (MCT) and bulldozed land with conventional tillage (BCT). The soil properties were determined at 0-40cm depths at intervals of 10 cm for analysis. Financial cost of these land preparation methods was also estimated from machinery input cost derivatives and information gathered from local farmers. Dry bulk density, porosity and hydraulic conductivity were significantly (at p ≤ 0.005 level) affected by the land preparations methods. At different depths of sampling, hydraulic conductivity was not significantly (at p ≤ 0.005 level) affected. However, available water content was not significantly affected by both factors (land preparation methods and depth of sampling). Dry bulk density at 1.5g/cm3 reduced by 3% and 16% in MCT and BCT respectively compared with the UNCULTIVATED and SBNT. The results showed that agricultural lands prepared by bulldozing or stumps excavation and conventional tillage operations (BCT) was most appropriate using fertile agricultural soil indicators of soil physical properties. The results also indicated that it costs three times more in preparing lands employing heavy tractors like the bulldozer compared to the traditional methods of using human labour with simple tools.Item The Effects of Inoculum Acclimatisation on the Methanogenesis of Ecklonia Maxima(University Of Ghana, 2020-06) Darko, C.N.S.In the present scenario of the over dependence and shortcomings of fossil fuels, integrated biorefinery techniques have been developed to process biodegradable and sustainable feedstock for use as green energy. Brown seaweed biomass, recently has been under the spotlight for the production of biogas via anaerobic digestion. In this study, the effects of acclimatising inoculum to Ecklonia maxima, a brown seaweed type for the production of biogas have been investigated. Biomass of Ecklonia maxima were subjected to an acclimatisation period to enable anaerobic microbes cultured on the inoculum adapt to the feedstock. Mixtures of Ecklonia maxima with either acclimatised or unacclimatised inoculum were prepared and anaerobically digested for a period of 20 days. The proximate and ultimate results carried on the feedstock confirmed them suitable for the purpose. The carbon, hydrogen, nitrogen and sulphur (CHNS) content analysis result was used to calculate the theoretical yield potential which was 1844.0 ml/gVS for Ecklonia maxima. SEM - EDX were conducted on the samples to observe their morphology and chemical compositions. Fourier transform infrared (FTIR) spectroscopy was further conducted to identify the bonds and functional groups where both spectra recorded the presence of carboxylic, hydroxyl, ketones and ethers groups. Samples of biogas produced were analysed using gas chromatography to characterise the percentage of carbon dioxide (CO2) and methane (CH4). An optimum amount of ~55% methane was recorded by the mixture of Ecklonia maxima and acclimatised inoculum. The cumulative biogas yield for acclimatised sample was recorded as 1571.8 ml/gVS, very similar to 1564.0 ml/gVS predicted as the biogas potential (A) at a production rate (μ) of 296.2 ml/day using the modified Gompertz equation. The volume of biogas generated from the feedstock implies a positive influence of acclimatising inoculum on E. maximaItem Effects of Metakaolin as Supplementary Cementitious Material in Mortars for Construction Applications(University of Ghana, 2018-07) Marfo, K.K.This work presents the effects of metakaolin as a supplementary cementitious material in mortars for construction applications. Kaolin from Teleku Bokazo was calcined at 650oC and partially used to replace Portland limestone cement to produce mortars and paste. The metakaolin was successfully used in a cement paste and its effect observed in the different cement replacements proportions. The replacements ranged from 10% - 35% by mass and characterised after 3, 7, 14 and 28 days of curing. Kaolin was characterized using X-ray diffractometer (XRD) with illite, kaolinite and quartz as the main crystalline phases. The metakaolin was also characterised using XRD with quartz as the main crystalline phase. Calcium silicate hydrate, calcium aluminium silicate hydrate, portlandite, calcite and ettringite were some of the hydrated compounds formed in the hydrated pastes. Fourier transform infrared spectroscopy was used to determine the functional groups of the hydrated cement products formed from the metakaolin cement paste. Other test including initial setting and water consistency were also carried out. Water consistency and setting times generally increased with increase in metakaolin addition. The optimum metakaolin replacement for flexural strength after 28 days curing was 15 and 20% whereas the compressive strength after 28 days curing was 20% metakaolin replacement. Generally, the metakaolin reduced the amount of water absorbed by capillary action for the 28 days cured mortar bars. The results suggest that 20% metakaolin replacements of Portland limestone possess characteristics that can be adopted for use in mortars for construction applications.Item Effects of Metakaolin as Supplementary Cementitious Material in Mortars for Construction Applications(University of Ghana, 2018-07) Marfo, K.K.This work presents the effects of metakaolin as a supplementary cementitious material in mortars for construction applications. Kaolin from Teleku Bokazo was calcined at 650oC and partially used to replace Portland limestone cement to produce mortars and paste. The metakaolin was successfully used in a cement paste and its effect observed in the different cement replacements proportions. The replacements ranged from 10% - 35% by mass and characterised after 3, 7, 14 and 28 days of curing. Kaolin was characterized using X-ray diffractometer (XRD) with illite, kaolinite and quartz as the main crystalline phases. The metakaolin was also characterised using XRD with quartz as the main crystalline phase. Calcium silicate hydrate, calcium aluminium silicate hydrate, portlandite, calcite and ettringite were some of the hydrated compounds formed in the hydrated pastes. Fourier transform infrared spectroscopy was used to determine the functional groups of the hydrated cement products formed from the metakaolin cement paste. Other test including initial setting and water consistency were also carried out. Water consistency and setting times generally increased with increase in metakaolin addition. The optimum metakaolin replacement for flexural strength after 28 days curing was 15 and 20% whereas the compressive strength after 28 days curing was 20% metakaolin replacement. Generally, the metakaolin reduced the amount of water absorbed by capillary action for the 28 days cured mortar bars. The results suggest that 20% metakaolin replacements of Portland limestone possess characteristics that can be adopted for use in mortars for construction applications.
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