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Propane (HC – 290) as an Alternative Refrigerant in the Food Transport Refrigeration Sector in Southern Africa – a Review
Get PDFThis research articles was published in Journals Automotive Experiences Volume Volume. 5 No.1,2022Most of the food transport trucks in Sothern Africa are equipped with refrigeration and air
conditioning systems filled with fluorocarbon refrigerants such as R404A to facilitate the heat
transfer process. These refrigerants are synthetic chemicals and have high potential to cause
global warming and damage to the ozone layer. Currently, natural refrigerants are considered
as alternatives to these man-made refrigerants to mitigate some of the environmental risks.
The natural refrigerants are the substances that occur in nature such as hydrocarbons (HC),
ammonia, and carbon dioxide. These type of refrigerants have been in the market for many
years, but in some applications such as domestic refrigerators, heat pumps, chillers, and air
conditioners, whereas fluorocarbons are the mostly used in the food transport refrigeration
systems. Natural refrigerants such as propane (HC – 290) are now penetrating the market in
food transport refrigeration systems where previously fluorocarbons were the favoured
option. Therefore, this work reports the possibilities of using non-fluorinated
hydrocarbon/natural refrigerant (propane – R290) in the food transport refrigerated systems
in Southern Africa; a case study of South Africa. R290 has the potential to lower greenhouse
gases emissions compared to hydrofluorocarbons (HFCs) which are widely used in most of
the existing food transport refrigeration systems in South Africa. R290 has negligible Global
Warming Potential (GWP) of 3 which is well below the global threshold value of 150. The
review revealed that refrigeration capacity of R290 is in the average of 10 – 30% higher than
commonly used fluorocarbon refrigerants such as R404A and R134A. Since R290 is labeled as
a flammable refrigerant, the present study also reviews its flammability safety measure
Pre-Breeding Prospects of Lablab (Lablab purpureus (L.) Sweet) Accessions in Tanzania: Morphological Characterization and Genetic Diversity Analysis
Get PDFThis research article was published by MDPI, 2022Under-exploited crops such as Lablab purpureus are regarded a pathway towards alleviating the food and nutritional security in Sub-Saharan Africa. This study aimed at evaluating the morpho-agronomic diversity present in 277 lablab accessions based on 38 morpho-agronomic traits. The experiment was laid out in an Augmented design across two main cropping seasons in Tanzania. Qualitative data was analysed using pivot tables. The Generalized Linear Model (PROC GLM), Agglomerative Hierarchical Clustering (AHC) and Principal Component Analysis (PCA) were used to analyse variation of 14 quantitative traits. The findings revealed the presence of wide variability of the qualitative traits in the studied accessions. Significant differences were observed among accessions, between seasons, the interaction of blocks and season, and the season and accession effects in most of the traits. Most of the traits had high significant differences in relation to contrast among accessions, among checks and between accessions and checks. The first five principal components cumulatively accounted for 61.89% of the total variability among the accessions studied. Furthermore, cluster analysis grouped the accessions into four major clusters. This results suggest the 14 morpho-agronomic traits can successfully discriminate and show presence of wide diversity vital for selection and hybridization program of lablab species
IoT based smart fan controller and fire prevention in computer laboratory
Get PDFA Project Report Submitted in Partial Fulfillment of the Requirements of the Award the Degree of Master of Science in Embedded and Mobile Systems of the Nelson Mandela African Institution of Science and TechnologyComputer laboratory plays the role of key elements with high interest for different categories
of populations. Event of fire, smoke, heat and water leakage when occurs could cause a big
loss for business continuity. Their equipment is very expensive and its usage is more profitable
to the population who used it. Many computer laboratories in the East Africa community region
are equipped with equipment for protection against fire, smoke, and heat such as fire
extinguishers, fans, and smoke detectors. However, when equipped with that equipment of
protection, a system for monitoring and controlling the computer laboratory environment and
warning the users in real-time is not yet implemented. This study aimed to develop an
automated computer laboratory that would control and monitor the computer laboratory
environment from the incident of fire, heat, smoke, and water leakage. The developed system
is divided into three nodes which communicate separately with one database in common where
the flame sensor is used to detect fire and allow the turning on automatically of a fire
extinguisher in case of fire detection, DHT22 and ultrasonic sensor are used for management
of fan controller, allowing to turn on automatically fan controller when there is high
temperature and if there is a presence of a person, smoke and water sensors are used to detect
the presence of smoke and water leakage. NodeMCU ESP8266, ESP32 WROOM-32D as a
microcontroller, access point, and software are used to accomplish the development of that
system. Different actions of warning users such as triggering buzzers and sending emails are
done when fire, smoke, and water leakage are detected, email is sent to the users when there is
a temperature more than 25℃. ThingSpeak cloud is used for the analysis of data from sensors,
control of fire extinguisher and fan controller were done via mobile application and web
applications. A prototyping methodology was used. The study aimed at interviewing 80
individuals based on their cluster. However, 64 individuals accepted to respond to our
questionnaires. Results showed that 57.81% of females were interested in the interview
compared to 42.19% of males. From the results which come of testing the prototype, it shows
that the variation of temperature varies between 23℃ and 27.60℃, 11 times of fire detection,
and 33 times of smoke detection. The developed system for IoT-based smart fan controllers
and fire prevention in computer labs with its supported equipment will contribute to securing
and protecting the computer laboratory against fire, smoldering, heating, and water leakage
Performance assessment of solar dryer integrated with heat energy storage system for food preservation
Get PDFA Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of Master’s in Sustainable Energy Science and Engineering of the Nelson Mandela African Institution of Science and TechnologySolar energy is regarded as a clean form of energy because solar radiation can be transformed
into heat energy for different applications such as heating water, generating power, cooking,
and drying food products. The solar dryer integrated with heat energy storage system in this
study was designed to use nitrate salt as a phase change material that can store thermal energy
during sun hours and then be used when the sun is not active. The dryer was tested by drying
1000 g of red peppers in a drying air temperature range of 19.6 – 62.4 °C, the average
temperature was 46 °C and ambient temperature ranges between 19.3 – 37.4 °C. The drying
process of the developed solar dryer was compared with an open sun drying system, each
loaded with 1000 g of red pepper. For 24 hours, the solar dryer maintained colour, flavor and
reduced the moisture content from 86% to the required 10% whereas open sun drying took 36
hours to accomplish the same result. It has been discovered that the payback period is 6.2 years,
which is low compared to the 22-year solar dryer life span. Thus, for 16 years, the solar dryer
will dry free products, which is feasible and economical
Forage selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) at multiple spatial scales
Get PDFThis research article was published by Oxford University Press, 2022Management of rangelands requires knowledge of forage species that are preferred or avoided by wildlife and livestock. A recent expansion of woody vegetation into previously open grasslands in African savanna ecosystems negatively impacts many mammalian grazers. Nevertheless, the ecological role of bush encroacher plant species as food may present a benefit for browsing species. We quantified diet selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) through foraging observations and vegetation sampling in the Tarangire Ecosystem of Tanzania, which includes large areas of a native shrub that livestock managers have classified as an encroacher species (Dichrostachys cinerea). We compared woody plant species used by giraffes for foraging with availability at two different spatial scales during the wet and dry seasons. Giraffes selected some woody plants such as Vachellia species while significantly avoiding others, both at the local and landscape scales. Giraffes preferred foraging on D. cinerea at both spatial scales and in both the wet and dry seasons. Management that has focused on benefiting grazing livestock by removal of encroaching species (e.g., D. cinerea) may have unintended consequences for wildlife, especially for browsing species like giraffes that feed extensively on the expanding bush species
Mathematical modelling approach to investigate transmission dynamics of covid-19 with some control parameters
Get PDFA Dissertation Submitted in Partial Fulfilment of the Requirements for the Degree of Master’s in Mathematical and Computer Sciences and Engineering of the Nelson Mandela African Institution of Science and TechnologyCOVID-19 is a world pandemic that has affected and continues to affect human lives, socially
and economically. Worldwide governments enforced preventive measures aimed at reducing the
disease transmission due to its social and economic impact. Examples of such measures are phys ical separation, quarantine, hand-washing, travel bans and border restrictions, lockdown, and the
use of hand sanitizers. Some of the control measures like quarantine was the most stressful strat egy for people to manage. To examine the impact of stress on the transmission of COVID-19,
this dissertation developed a mathematical model with six compartments; Susceptible-Exposed Quarantine-Infectious-Hospitalized-Recovered (SEQIHR). The model was then analyzed both
theoretically and numerically. In theoretical analysis, terms like positivity, bounded region, exis tence, uniqueness of the solution, model existence of free and endemic equilibrium points, local
and global stability are all utilized. The basic reproduction number (R0) was calculated using the
next-generation matrix approach. When R0 1, the endemic equilibrium is globally asymptotically stable.
The Partial Rank Correlation Coefficient (PRCC) was used to evaluate the relationship between
model parameters and R0. The model was numerically solved using the fourth-order Runge-Kutta
method, and parameter identifiability was achieved using least square and Markov Chain Monte
Carlo (MCMC) methods. The formulated deterministic model explored the impact of stress in
quarantine to the human population and revealed that when an individual’s mental health is good,
the body immunity becomes strong. Conclusively, the control parameters have a considerable
impact on COVID-19 transmission minimization
Development of low-cost IOT based infant incubator in Tanzania: a case of east African community region
Get PDFA Project Report Submitted in Partial Fulfillment of the Requirements of the Award of the Degree of Master of Science in Embedded and Mobile System of the Nelson Mandela African Institution of Science and TechnologyPhysical adjustment to life outside of the mother's body of a baby might be challenging due to
health issues and other environmental factors. Prematurity is one of the most crucial problems
in Tanzania since it contributes to a greater infant mortality rate. Despite the vital function that
infant incubators play, their operation cost is too expensive for low-income countries to obtain
and it relies only on electricity for their operation. The fundamental goal of this project is to
create an inexpensive, efficient, and dual-powered incubator that saves premature infants' lives.
We developed the system which utilizes ESP32 as the Microcontroller Unit board interfaced
with DHT22, a thermistor for skin temperature computation, MAX30102 to evaluate heart rate
and oxygen saturation in the blood. An oxygen sensor measures the air quality in the chamber,
and a ultraviolet sensor records the light intensity of the phototherapy unit used to treat
jaundice. The computed information is displayed and transferred to a webpage that tracks the
infant's data. When the system detects a critical condition, it sounds an alarm and sends short
messege services to medical personnel via Global System for Mobile Communication. The
system adjusts the environment using a heater, humidifier, and oxygen valve. The final design
was implemented on a Printed Circuit Board and tested after a circuit was designed and
simulated. The sensors were calibrated against standard sensors to receive accurate measured
data, and then transferred via Wi-Fi through the ESP32 to a webpage for remote monitoring
and control. In conclusion, based on the test-performed the developed system can save the lives
of premature babies, is low-cost, and is applicable in areas with limited resources. Furthermore,
we recommend an easy way to assess the functionality of the locally developed systems by the
regulatory institutions involved so as to be implemented successfully
Inter-epidemic Rift Valley fever virus infection incidence and risks for zoonotic spillover in northern Tanzania
Get PDFThis research article was published by PLOS in 2022Rift Valley fever virus (RVFV) is a mosquito-borne pathogen that has caused epidemics involving people and animals across Africa and the Arabian Peninsula. A number of studies have found evidence for the circulation of RVFV among livestock between these epidemics but the population-level incidence of infection during this inter-epidemic period (IEP) is rarely reported. General force of infection (FOI) models were applied to age-adjusted cross-sectional serological data to reconstruct the annual FOI and population-level incidence of RVFV infection among cattle, goats, and sheep in northern Tanzania from 2009 through 2015, a period without reported Rift Valley fever (RVF) cases in people or animals. To evaluate the potential for zoonotic RVFV spillover during this period, the relationship between village-level livestock RVFV FOI and human RVFV seropositivity was quantified using multi-level logistic regression. The predicted average annual incidence was 72 (95% Credible Interval [CrI] 63, 81) RVFV infections per 10,000 animals and 96 (95% CrI 81, 113), 79 (95% CrI 62, 98), and 39 (95% CrI 28, 52) per 10,000 cattle, sheep, and goats, respectively. There was variation in transmission intensity between study villages, with the highest estimated village-level FOI 2.49% (95% CrI 1.89, 3.23) and the lowest 0.12% (95% CrI 0.02, 0.43). The human RVFV seroprevalence was 8.2% (95% Confidence Interval 6.2, 10.9). Human seropositivity was strongly associated with the village-level FOI in livestock, with the odds of seropositivity in an individual person increasing by around 1.2 times (95% CrI 1.1, 1.3) for each additional annual RVFV seroconversion per 1,000 animals. A history of raw milk consumption was also positively associated with human seropositivity. RVFV has circulated at apparently low levels among livestock in northern Tanzania in the period since the last reported epidemic. Although our data do not allow us to confirm human RVFV infections during the IEP, a strong association between human seropositivity and the FOI in cattle, goats, and sheep supports the hypothesis that RVFV circulation among livestock during the IEP poses a risk for undetected zoonotic spillover in northern Tanzania. We provide further evidence for the likely role of raw milk consumption in RVFV transmission from animals to people
Determinants of Agropastoralist Households’ Fodder Accessibility and Rangeland Conservation in Magu District, Tanzania
Get PDFThis research article was published by Elsevier in 2022The availability and accessibility of adequate and quality fodder is a huge challenge for pastoral and agropastoralist communities in Tanzania. Fodder scarcity, primarily driven by rangeland degradation, population growth, and climatic changes, limits livestock productivity and deepens rural poverty. This study assessed factors influencing agropastoralists’ access to fodder and their willingness to conserve fodder sources in Magu District, Tanzania. A total of 210 agropastoralist households were surveyed in three wards covering six villages. The results show that access to fodder during the wet season is positively influenced by a household's income, land size, number of livestock, and physical capital. Dry season fodder accessibility is negatively influenced by households’ land size, physical capital, and the number of livestock. Results also show that more than 60% of the agropastoral households accessed fodder sources formally (legally) in open areas, while 35% accessed fodder informally (illegally) in traditionally reserved highland areas, people's farms, and restricted urban areas. Conservation of rangelands and fodder sources is positively influenced by a head of households’ level of education and income, and only 40% of households participated in conservation of rangelands and fodder sources. Improved land tenure, education, and income diversification can improve households’ access to fodder and their willingness to conserve fodder sources
Usability and user experience of Moodle learning management system into higher learning of Tanzania
Get PDFA Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Master’s in Information and Communication Science and Engineering of the Nelson Mandela African Institution of Science and TechnologyAccording to previous works, Learning Management Systems (LMSs) have been facing
obsolete rendering barriers such as accessibility of the system due to network disruption and
bandwidth expenses, Digital literacy, user’s perception towards the use of an online LMS in
taking a course, policies towards E-learning acceleration and support, Information literacy,
technological barriers, lack of relevant technical training and assistance in using LMS for the
instructors, LMS’s lack the ability to cater for the cultural differences, navigational issues, and
misrepresentation of contents and insufficient content and credible resources. This study
applied a mixed methodology and data collection was carried online, with sample survey of
open and closed ended questionnaires and online interviews. Sampling technic used was
snowball and the case of convenience which involved 338 participants inclusive of 112
facilitators/teachers and 226 students.
Identified prominent existing barrier by users was navigational issues, and misrepresentation
of contents, which associated user experience and usability issues, using an open and free
learning management system Moodle, a “Jifunze kwa Moodle” prototype was created.
Assessment was conducted to identify tools to be applied and improve user experience and
usability in the final prototype of the “Jifunze Kwa Moodle” platform using Rapid Application
Development.
Online teaching and learning tools such as H5P and BigBlueButton were integrated into the
platform to entice interaction between facilitator and students. The platform was shared, and
only 20 users had accomplished the tasks assigned, thus 6 facilitators and 14 students. Users
assessed the platform through task-based scenarios so as to accommodate responses and
improve the platform, tasks such as initiating a class using H5P and BigBlueButton were
essential for the instructors and students had to attend some sessions. Conclusively this study
opens up the opportunity to engage in making learning management systems user friendly,
interactive and simpler using online teaching and learning tools to accommodate different
users’ need