Online Journal of Engineering Sciences

Journal profile

Online Journal of Engineering Sciences 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.

Latest Articles

Open Access November 4, 2022 Endnote/Zotero/Mendeley (RIS) BibTeX

An Artificial Intelligence Approach to Manage Crop Water Requirements in South Africa

Online Journal of Engineering Sciences 2022, 2(1), 23-34. DOI: 10.31586/ojes.2022.377
Abstract
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
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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 (R2) of 0.94. The validation of the model between the measured and predicted ETo 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.Full article
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Research Article
Open Access August 27, 2022 Endnote/Zotero/Mendeley (RIS) BibTeX

Thermal Energy Consumption Assessment in a Fluid Milk Plant

Online Journal of Engineering Sciences 2022, 2(1), 13-22. DOI: 10.31586/ojes.2022.392
Abstract
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
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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 m3 of water allow assessing the feasibility of an investment project for improved heat recovery.Full article
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Research Article
Open Access August 24, 2022 Endnote/Zotero/Mendeley (RIS) BibTeX

Performance Analysis of an Ultra-Wide Band (UWB) Antenna for Communication System

Online Journal of Engineering Sciences 2022, 2(1), 1-12. DOI: 10.31586/ojes.2022.359
Abstract
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
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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.Full article
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Review Article
Open Access July 10, 2022 Endnote/Zotero/Mendeley (RIS) BibTeX

Spray Coated Cellulose Nanofiber (CNF) Film as an Eco-Friendly Substrate for Flexible and Printed Electronics

Online Journal of Engineering Sciences 2022, 1(1), 68-81. DOI: 10.31586/ojes.2022.352
Abstract
Cellulose nanofiber is an eco-friendly nanomaterial used for fabricating various functional materials. It is an alternative for synthetic plastic and other petroleum derived materials. Due to demand of CNF film, fast and rapid method for fabrication of CNF film is required. A new method on spray coating to prepare smooth
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Cellulose nanofiber is an eco-friendly nanomaterial used for fabricating various functional materials. It is an alternative for synthetic plastic and other petroleum derived materials. Due to demand of CNF film, fast and rapid method for fabrication of CNF film is required. A new method on spray coating to prepare smooth cellulose nanofiber (CNF) films was developed. In this method, spraying CNF suspension onto a smooth and polished metal surface was carried out and then allowed the spray coated wet film to dry in air under standard laboratory conditions. Spraying has notable advantages such as contour coating and contactless coating with the base substrate. The basis weight and thickness of the CNF film is tailorable by adjusting CNF suspension in spraying process. CNF film prepared via spray coating has unique two-sided surface roughness with the surface in contact with the base substrate or metal side much smoother than the air-contact side. The surface roughness is one of the controlling parameter in the application of the CNF film as a substrate for flexible and printed electronics. The RMS roughness of the two surfaces investigated by Optical Profilometry [OP] was found to be 2087 nm on the rough side and 389 nm on the spray coated side, respectively. The spray coated CNF film has ultra-high smoothness on the side exposed to the polished stainless steel surface. The factors including the size of cellulose fibrils and surface smoothness of base surface that control the roughness of the film are currently being investigated and will be discussed in this chapter. The surface smoothness requirements for substrate applications in flexible and printed electronics will be discussed.Full article
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Concept Paper
Open Access June 9, 2022 Endnote/Zotero/Mendeley (RIS) BibTeX

Theoretical and Experimental Analysis of Miniaturization of Conventional Oscillatory Flow Technology

Online Journal of Engineering Sciences 2022, 1(1), 45-67. DOI: 10.31586/ojes.2022.296
Abstract
The requirement for any configuration of a chemical or biochemical reactor is the presence of efficient mixing to enhance heat and mass transfer as needed for the application of interest. Furthermore, as an Oscillatory Flow (OF) reactor has a combination of flow oscillation and baffled tube configuration, which has the
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The requirement for any configuration of a chemical or biochemical reactor is the presence of efficient mixing to enhance heat and mass transfer as needed for the application of interest. Furthermore, as an Oscillatory Flow (OF) reactor has a combination of flow oscillation and baffled tube configuration, which has the potential to ensure efficient mixing, heat transfer, and mass transfer. In this way, an efficient mixing in an OF reactor is able to tackle any type of resistance in any chemical process from polymer synthesis to enzyme production. It has been observed that an OF reactor improved both conversion and selectivity of the relevant reaction by efficient mixing and transport properties. However, this technology was not still extended to mini-fluidic configuration via process intensification methods and so far, a novel approach for enhanced mixing at reduced scales was not explored. This work explores the application of OF technology in mini-fluidics. The feasibility analysis of Oscillatory Flow Technology in mini channels has been investigated using theoretical correlations from Conventional Oscillatory flow technology in process equipment. As a preliminary step in the process intensification of OF technology in mini channels, The Nusselt number (Nu) and pressure drop values are predicted from the literature and it has been observed that the transfer operations are also improved when oscillatory flow is applied in mini channels compared to commercial mini contactors such as corning heart shaped reactor. The plot between energy dissipation vs. mixing evaluated from theoretical calculations was drawn and compared with mini-fluidic mixers reported in literature. The most common mini-fluidic mixer is corning heart shaped reactor used for comparison with the proposed minichannel. Because of this analysis, the novel mixing geometries was expected to develop for various chemical processing applications. The OFT experimental set up was developed to create oscillatory flow via either forward rotation or backward rotation of valve. Furthermore, pressure vs. time profile and flow vs. time profile for the given OF mini fluidic arrangement is initially investigated and described. Preliminary experimental results are provided for an OF generator, intended for use in subsequent experiments exploring mini-fluidic mixers with OF technology.Full article
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Article
Open Access February 24, 2022 Endnote/Zotero/Mendeley (RIS) BibTeX

Computational Fluid Dynamics Modeling of Thermally Integrated Microchannel Reforming Reactors for Hydrogen Production

Online Journal of Engineering Sciences 2022, 1(1), 29-44. DOI: 10.31586/ojes.2022.228
Abstract
Many attempts have been made to improve heat transfer for thermally integrated microchannel reforming reactors. However, the mechanisms for the effects of design factors on heat transfer characteristics are still not fully understood. This study relates to a thermochemical process for producing hydrogen by the catalytic endothermic reaction of methanol
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Many attempts have been made to improve heat transfer for thermally integrated microchannel reforming reactors. However, the mechanisms for the effects of design factors on heat transfer characteristics are still not fully understood. This study relates to a thermochemical process for producing hydrogen by the catalytic endothermic reaction of methanol with steam in a thermally integrated microchannel reforming reactor. Computational fluid dynamics simulations are conducted to better understand the consumption, generation, and exchange of thermal energy between endothermic and exothermic processes in the reactor. The effects of wall heat conduction properties and channel dimensions on heat transfer characteristics and reactor performance are investigated. Thermodynamic analysis is performed based on specific enthalpy to better understand the evolution of thermal energy in the reactor. The results indicate that the thermal conductivity of the channel walls is fundamentally important. Materials with high thermal conductivity are preferred for the channel walls. Thermally conductive ceramics and metals are well-suited. Wall materials with poor heat conduction properties degrade the reactor performance. Reaction heat flux profiles are considerably affected by channel dimensions. The peak reaction heat flux increases with the channel dimensions while maintaining the flow rates. The change in specific enthalpy is positive for the exothermic reaction and negative for the endothermic reaction. The change in specific sensible enthalpy is always positive. Design recommendations are made to improve thermal performance for the reactor.Full article
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Research Article
Open Access December 15, 2021 Endnote/Zotero/Mendeley (RIS) BibTeX

Dissemination and Exploitation of Regional Meteo-Hydrological Datasets through Web-based Interactive Applications: The SOL System Case Study

Online Journal of Engineering Sciences 2022, 1(1), 19-28. DOI: 10.31586/ojes.2021.180
Abstract
The effects of climate change are already being felt in several parts of the World. Variability of changing rainfall intensity, drought and weather patterns contribute to determining the vulnerability of many human activities such as agriculture. In the next future, climate change considerations will depend on having appropriate strategies such
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The effects of climate change are already being felt in several parts of the World. Variability of changing rainfall intensity, drought and weather patterns contribute to determining the vulnerability of many human activities such as agriculture. In the next future, climate change considerations will depend on having appropriate strategies such as strengthen implementation agencies working in a coordinated manner and with a data-driven approach in order to ensure monitoring, reporting and data verification. In this context, national and regional meteorological Services are facing with high demand for timely and quality information, services and products. A web-based interactive application with the aim of disseminating meteo-hydrological information at regional scale is described in this paper. The web application is built on a relational database and client-side programming has been used for implementing the user interface and controlling the web page behavior. The combination of PHP (Hypertext Preprocessor, a general-purpose scripting language, especially suited to server-side web development) and JavaScript (high-level object-oriented scripting language, nowadays the dominant client-side scripting language of the Web) has been chosen for this reason, since such software is free to use for everyone. The SOL system, developed on behalf of Marche region, Italy, was chosen as a case study, due to its multi-source data framework and because of the processing and public dissemination of several ad-hoc data elaborations.Full article
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Case Study
Open Access August 21, 2021 Endnote/Zotero/Mendeley (RIS) BibTeX

Virologic Microparticle Fluid Mechanics Simulation: COVID-19 Transmission in the Protected and Unprotected Conversations

Online Journal of Engineering Sciences 2021, 1(1), 1-18. DOI: 10.31586/ojes.2021.010101
Abstract
SARS-COV-19 is a serious respiratory infection created by a devastating coronavirus family (2019-nCoV) that has become the first global epidemic of the last one hundred years. It is a highly transmissible virus transmitted by inhalation or contact with the droplet core produced by infected people when they sneeze, cough, and
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SARS-COV-19 is a serious respiratory infection created by a devastating coronavirus family (2019-nCoV) that has become the first global epidemic of the last one hundred years. It is a highly transmissible virus transmitted by inhalation or contact with the droplet core produced by infected people when they sneeze, cough, and speak. SARS-COV-2 transmission in the air is possible even in a confined space near the infected person. This study aimed to evaluate the effectiveness of using a shield or mask as a barrier to a patient’s face against the spread of virus particles. For the present simulation, the discrete phase model (DPM) is used; Because this model allows us to study the particle’s mass discretely in a fluid space with the continuous phase. Due to the choice of this model, the virus particles secreted from the patient’s mouth are considered a discrete phase, and the open airflow in the computational area is considered a continuous phase. The present study uses fluent 2019R3 software to simulate the virus transmission to model the transient flows numerically. The analysis found that the masks or shields can be an effective method of protecting the participants of a conversation in the presence of an infected person.Full article
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Review Article

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ISSN: 2833-0145
DOI prefix: 10.31586/ojes
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2021-2022
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