Online Journal of Engineering Sciences https://www.scipublications.com/journal/index.php/ojes <p><em><strong>Online Journal of Engineering Sciences</strong></em> is an international, peer reviewed and open access journal providing a unique forum for researchers, scholars and practitioners to concern dynamic and rapid evolution of knowledge in the engineering field. This journal publishes high-quality original research, case reports, reviews and meeting reports.</p> en-US Online Journal of Engineering Sciences An Artificial Intelligence Approach to Manage Crop Water Requirements in South Africa https://www.scipublications.com/journal/index.php/ojes/article/view/377 <p>Estimation of crop water requirements is of paramount importance towards the management of agricultural water resources, which is a major mitigating strategy against the effects of climate change on food security. South Africa water shortage poses a threat on agricultural efficiency. Since irrigation uses about 60% of the fresh water available, it therefore becomes important to optimise the use of irrigation water in order to maximize crop yield at the farm level in order to avoid wastage. In this study, combined application of an artificial neural network (ANN) and a crop – growth simulation model for the estimation of crop irrigation water requirements and the irrigation scheduling of potatoes at Winterton irrigation scheme, South Africa was investigated. The crop-water demand from planting to harvest date, when to irrigate, the optimum stage in the drying cycle when to apply water and the amount of irrigation water to be applied per time, were estimated in this study. Five feed –forward backward propagation artificial neural network predictive models were developed with varied number of neurons and hidden layers and evaluated. The optimal ANN model, which has 5 inputs, 5 neurons, 1 hidden layer and 1 output was used to predict monthly reference evapotranspiration (ETo) in the Winterton area. The optimal ANN model produced a root-mean-square error (RMSE) of 0.67, Pearson correlation coefficient (r) of 0.97 and coefficient of determination (R<sup>2</sup>) of 0.94. The validation of the model between the measured and predicted ET<sub>o</sub> shows a r value of 0.9048. The predicted ETo was one of the input variables into a crop growth simulation model, called CROPWAT. The results indicated that the total crop water requirement was 1259.2 mm/decade and net irrigation water requirement was 1276.9 mm/decade, spread over a 5-day irrigation time during the entire 140 days of cropping season for potatoes. A combination of the artificial neural networks and the crop growth simulation models have proved to be a robust technique for estimating crop irrigation water requirements in the face of limited or no daily meteorological datasets.</p> Akinola Ikudayisi Andre Calitz Samuel Abejide Copyright (c) 2022 Online Journal of Engineering Sciences 2022-11-04 2022-11-04 23 34 Thermal Energy Consumption Assessment in a Fluid Milk Plant https://www.scipublications.com/journal/index.php/ojes/article/view/392 <p>The main energy conservation opportunities in a dairy plant are in refrigeration, and steam generation. This paper aims to identify potential energy and water savings and opportunities to improve the thermal efficiency of a fluid milk processing plant, using energy analysis and Heat Integration methods. Methodologies for energy analysis and Pinch Analysis with the use of HENSAD and Aspen Energy Analyzer are applied. The main specific energy consumptions are defined as indicators of the progress of improved energy efficiency. The determination of energy performance indicators and energy targets of the heat exchanger network, as well as its design, allowed identifying opportunities for improvement to reduce fuel and water consumption through heat recovery in the milk pasteurization process. Current hot and cold utilities duties are satisfied, for a minimum allowable temperature difference of 20 °C. Total annual savings of 60 t of fuel oil and 15,800 m<sup>3</sup> of water allow assessing the feasibility of an investment project for improved heat recovery.</p> Juan Pedro Hernández Touset L. Roche Delgado Copyright (c) 2022 Online Journal of Engineering Sciences 2022-08-27 2022-08-27 13 22 Performance Analysis of an Ultra-Wide Band (UWB) Antenna for Communication System https://www.scipublications.com/journal/index.php/ojes/article/view/359 <p>A spherical shape ultra-wideband antenna is a microstrip patch antenna whose emitted signal bandwidth exceeds the lesser of 500 MHz. One of the major issues hindering the ultra-wideband antennas is poor diversity factors, poor voltage standing wave ratio and poor power efficiency to transmit the required signals. In this research work, the method of approach is the design and analysis of a spherical shape ultra-wideband antenna with the use of computer simulation technology (CST). This antenna is working under the resonant frequency of 6 GHz on a frequency bandwidth of 4-9 GHz. However, this research work has made an intensive review of related works. A spherical shape microstrip antenna with a diameter of 13mm and a radius of 6.5mm was designed, after which a simulation was carried out using the computer simulation technology software. The result from the radiated power shows how high the radiative efficiency is and from the results we were able to observe that the ultra-wideband antenna uses a very low amount of power but can transmit a better outgoing power from the 0.5 watts stimulated power. In this research work, an evaluation process on the envelope correlation coefficient of the antenna s-parameters was carried out, with a good result was obtained. Most importantly the diversity gain of the antenna proves to be good and efficient due to the effectiveness of the antenna radiation efficiency. The results of this antenna produce a very good voltage standing wave ratio (VSWR), the voltage standing wave ratio of this spherical ultra-wideband antenna is less than 2% with a very low return loss reflection. In conclusion, the spherical shape antenna is good for ultra-wideband purposes because of its robustness in delivering high-quality signals with a very low return loss. So, it stands the chance of recommendations in the communication industries due to its high radiation efficiency rate and good VSWR.</p> Promise Elechi Chinwe P. Obi-Ijeoma Copyright (c) 2022 Online Journal of Engineering Sciences 2022-08-24 2022-08-24 1 12