Journal of Technological Sciences

Editorial for Journal of Technological Sciences

Robert Musundire — Wed, 24 Aug 2022 00:00:00 +0000

It is with great pleasure that I present this first issue of the Journal of Technological Sciences as a Chinhoyi University of Technology publication. This issue comes after a long break from publication by the Zimbabwe Journal of Technological Sciences (ZJTS) which is the predecessor of this journal. The last issue for ZJTS was in 2015. A number of changes have occurred at Chinhoyi University of Technology’s research profile as well as the overall national and international focus regarding research and development, thus necessitating the modification of title and focus areas of the journal. For example, the most significant shift in the higher education sector globally requires that education should yield innovations, goods and services that have societal impact.

Establishing the most cost effective reliability for off-grid solar systems in Zimbabwe

Sharon Kavu, Professor Maria Tsvere, Professor Wilbert Mtangi, Tawanda Hove — Wed, 24 Aug 2022 00:00:00 +0000

The traditional method for designing off-grid stand-alone solar energy systems is based on a monthly-average daily energy balance approach whose only objective is to provide 100% energy supply reliability. However, such an approach tends to grossly oversize the systems thus rendering solar off-grid systems too costly for the target communities. This study has focused on designing a cost effective off-grid solar power system to ensure balancing of the trade-off between cost and reliability of power supply. Based on a time-step energy balance approach, an Excel spreadsheet-based model was developed to optimise the solar stand-alone system. Two dimensionless variables representing the size of the two main components of a solar photovoltaic off-grid system- the solar photovoltaic (PV) array and battery- were used to define the system size. For a given level of supply reliability, there is an infinite number of combinations of PV array and battery size- as the PV array size is increased, the required battery size reduces in a certain trend. However, for the given level of reliability, only one PV array-battery combination (the Optimum Design) results in the minimum Levelised Cost of Energy (LCOE), whose coordinates depend on the relative costs of the two components. The LCOE for the Optimum Design corresponding to each level of supply reliability was plotted against supply reliability. From such a plot it was observed that the LCOE increases disproportionately above a certain level of reliability. This point, which lies near the “elbow” LCOE-reliability plot, defines the most cost-effective reliability for the stand-alone solar system, and therefore the optimum combination of PV generator and battery to deploy. The results showed that sustainable cost effective off-grid systems can be operated at 98% reliability level and still satisfy the customer requirements and at the same time ensuring affordable tariffs. Increasing the PV system components beyond the optimum (98% reliability) point, in a quest to achieve 100% reliability, results in a disproportionate 22% increase in LCOE.

Pit silos require hermeticity to serve as an alternative low cost storage facility for maize grain by smallholder farmers

Elizabeth Binga, Nilton Mashavakure, Jonathan Makaranga, Robert Musundire — Wed, 24 Aug 2022 00:00:00 +0000

Improved grain storage is important in reducing postharvest losses and ensuring food security particularly among smallholder farming communities. In this study, a survey was carried out to establish grain storage practices and farmer perceptions among smallholder communities using 60 farmers in Shurugwi District, Zimbabwe. This was followed by a pilot scale study to test the effectiveness of the pit silo as a low-cost storage system for resource-constrained smallholder farmers. Four storage systems (pit silo, hermetic bag, insecticide-treated polypropylene bag and untreated polypropylene bag) were tested at Chinhoyi University farm, Zimbabwe, from December 2017 to May 2018, then for the same period in 2018 to 2019, using a completely randomised design replicated four times. Survey results showed that 96% of the farmers stored their maize grain in unimproved facilities. Most farmers (90%) stored their grain harvests for less than 12 months. Grain that was stored in pit silos contained the highest moisture (12.7-13.8%) while that stored in hermetic and untreated polypropylene bag had the lowest moisture content (8.5-9.7%). Pit silos had higher insect pest infestation than hermetic and insecticide-treated polypropylene bags but had as much as three times fewer insects than untreated polypropylene bags. The highest (30%) and lowest (16%) grain weight losses were recorded under pit silo and hermetic bag storage, respectively. Germination percentage was also least in pit silo and greatest in hermetic bag storage. Pit silo stored grain contained higher concentrations of aflatoxins AFB1 (24.8 ppb) and AFG1 (6.4 ppb) relative to hermetic and untreated bag storage (0-0.8 ppb). The results of this study suggest that whilst pit silos perform better than unimproved systems such as untreated bags, further design work is required for it to match other efficient systems like the hermetic bag.

Design and performance assessment of an automatic grain moisture measuring system for use in Zimbabwe

Wed, 24 Aug 2022 00:00:00 +0000

Grain moisture content is a key index of grain processing, marketing, and storage security. Hence, its precise determination is of paramount importance. This paper presents the design and performance assessment of an automatic grain moisture measuring system for use in Zimbabwe, based on a microprocessor, photo sensor and moisture sensor. This research has been inspired by the need to eliminate the conventional oven drying based grain moisture content determination technique in use at most Grain Marketing Board (GMB) depots in Zimbabwe. The conventional oven drying technique has the following shortfalls: time-consuming, not suitable for online testing, results in unwarranted wastage of grains due to its destructive nature and the small testing sample is not an accurate representation of the whole grain sample. The performance index that was assessed for the designed system is the system processing time. The average processing time for the system is 3 milli seconds per grain bag. Based on the Mean Absolute Percentage Error (MAPE) the system’s grain moisture content determination accuracy is 98.92%. Compared to the conventional oven drying method, the designed system significantly reduces process time and is equally accurate. Hence, the designed system is a suitable replacement for the conventional method in Zimbabwean grain marketing depots.

Modelling of hourly solar radiation collected on a tilted surface at Banket in Mashonaland West, Zimbabwe for optimum design of off-grid solar systems.

Shorai Kavu, Maria Tsvere, Wilbert Mtangi, Tawanda Hove — Wed, 24 Aug 2022 00:00:00 +0000

Off-grid solar systems have become the most viable means of bringing electricity to sparsely populated rural communities of sub-Saharan Africa. This mostly because of the sharply falling prices of solar equipment and the maturity of the technology. The solar systems are also modular thus can be deployed at variety capacities for different applications. Zimbabwe has abundance solar resources ubiquitously spread country over. The design of the systems has however, been based on average country radiation which usually under-estimate or overestimate the insolation at a given site. This therefore affects the sizing of the systems and thus the cost. Also for off-grid systems it is not economical to carryout data collection of at least a year, which is another way to get accurate data. This study resorted to satellite data available on a freely accessible EU site as Typical Meteorological Year Data of 2009 downloaded using the Banket coordinates. The TMY data was used as the input to the model where, radiation data was input into the mathematical model of the tilted plane by Collares-Perreira and Rabl of 1996. Feeding the horizontal, beam and diffuse radiation data plus the ambient temperature into mathematical models resulted in the calculation of the solar radiation that can be received on a plane tilted at an angle equal to the latitude of the place. The data plotted for the whole year is a closer representative of the distribution of radiation received at the site for the whole year and thus reliable input to the design of off-grid solar systems as literature can confirm.

Poultry endogenous biosurfactants based feed additive, a potential counter to Antimicrobial resistance (AMR) challenge

Wed, 24 Aug 2022 00:00:00 +0000

Biosurfactants are amphiphilic microbial secretions containing surface-active biomolecules produced on living surfaces, such as microbial cell surfaces or extracellular surfaces. They possess a variety of characteristics that enable secreting microorganisms to withstand a variety of stressful situations, allowing them to conquer a variety of habitats. Biosurfactants also allow secreting microorganisms to destabilize other bacteria in competition for clinging surfaces, habitats, and substrates, ensuring their survival. Periods of extreme stress are unavoidable in birds, resulting in dysbacteriosis and the production of biofilms by less helpful bacteria. This stressful environment causes a broiler's feed utilization efficiency and immunity to be weakened, increasing the risk of coccidiosis. Farmers utilize a number of antimicrobial treatments to combat decreased immunity and performance, which could lead to drug residue in meat and other poultry products. Residual drugs will exacerbate antimicrobial drug resistance (AMR), which is believed to be around 60% in Zimbabwean cities. The researchers were inspired to look into endogenous biosurfactants after learning about the interesting properties of bacterial metabolites. A desk top study was carried out primarily employing sources to uncover the potential of biosurfactants in the twenty-first century. Many researchers were found to be employing exogenous microorganisms, and the majority of their studies were aimed at cleaning up polluted places. Biosurfactants have a number of features that are relevant to agriculture. Less study has been done on the advantages of endogenous biosurfactants. Biosurfactants are secreted by a variety of microorganisms, primarily bacteria. It is necessary to identify biosurfactant-secreting microbial species and describe their microbial secretions. For the poultry sector, a biosurfactant-based feed supplement can be developed to help combat antimicrobial resistance.

The design of an automated CO emission control system for automobiles using activated carbon.

Martin Masheka, Downmore Musademba, Engelbert Kapuya, Mercy Chinyuku — Wed, 24 Aug 2022 00:00:00 +0000

Air pollution has been found to be so hazardous to human health and life, ecosystem and infrastructure. One of the main contributors to air pollution is transportation. The aim of this research was to design an automated emission control system for automobiles. Four design frameworks were made and the one with three emission control technologies (Exhaust Gas Recirculation (EGR), Exhaust Gas Collection Tank (EGCT) and catalytic converters) had the highest score of 300.70. However, in this research, a system focused on controlling cold start emissions using activated carbon as an adsorbent for carbon monoxide (CO) was implemented. It was found that activated carbon can reduce CO pollutants by an average CO reduction percentage of 6.28% when 96.88g of activated carbon was applied at an average temperature of 34.75℃. However, applying activated carbon was found to reduce temperature by an average temperature reduction of 11.66℃. This was achieved through an algorithm that was designed to control exhaust gas flow and implemented using AT mega 2560 microcontroller, MQ7 sensors, LM35 temperature sensors, stepper motors and butterfly valves. MQ7 sensors were used for CO detection. However, ceria-based sensors could be used to increase the scope of temperatures and redirect exhaust gases to activated carbon whenever high emission is detected.