Allan De Freitas

Dr. Allan De Freitas

orcid

Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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4 January 2019 in IEEE Transactions on Vehicular Technology
Verified
Journal Article
Closed access
WAWaqas Aftab
Waqas Aftab
RHRoland Hostettler
Roland Hostettler
AFAllan De Freitas
Allan De Freitas
MAMahnaz Arvaneh
Mahnaz Arvaneh
LYUDMILA MIHAYLOVALYUDMILA MIHAYLOVA
LYUDMILA MIHAYLOVA

23 August 2024 in World Electric Vehicle Journal
Verified
Journal Article
Open access
PDF file
MOMuhtahir Oloyede
Muhtahir Oloyede
GAGodfrey A. Akpakwu
Godfrey A. Akpakwu
HMHerman Myburgh
Herman Myburgh
AFAllan De Freitas
Allan De Freitas
TKTawanda Kunatsa
Tawanda Kunatsa
Exact state-of-charge estimation is necessary for every application related to energy storage systems to protect the battery from deep discharging and overcharging. This leads to an improvement in discharge efficiency and extends the battery lifecycle. Batteries are a main source of energy and are usually monitored by management systems to achieve optimal use and protection. Coming up with effective methods for battery management systems that can adequately estimate the state-of-charge of batteries has become a great challenge that has been studied in the literature for some time. Hence, this paper analyses the different energy storage technologies, highlighting their merits and demerits. The various estimation methods for state-of-charge are discussed, and their merits and demerits are compared, while possible applications are pointed out. Furthermore, factors affecting the battery state-of-charge and approaches to managing the same are discussed and analysed. The different modelling tools used to carry out simulations for energy storage experiments are analysed and discussed. Additionally, a quantitative comparison of different technical and economic modelling simulators for energy storage applications is presented. Previous research works have been found to lack accuracy under varying conditions and ageing effects; as such, integrating hybrid approaches for enhanced accuracy in state-of-charge estimations is advised. With regards to energy storage technologies, exploring alternative materials for improved energy density, safety and sustainability exists as a huge research gap. The development of effective battery management systems for optimisation and control is yet to be fully exploited. When it comes to state-of-the-art simulators, integrating multiscale models for comprehensive understanding is of utmost importance. Enhancing adaptability across diverse battery chemistries and rigorous validation with real-world data is essential. To sum up the paper, future research directions and a conclusion are given.

4 October 2018 in IEEE Transactions on Aerospace and Electronic Systems
Verified
Journal Article
Closed access
AFAllan De Freitas
Allan De Freitas
LYUDMILA MIHAYLOVALYUDMILA MIHAYLOVA
LYUDMILA MIHAYLOVA
AGAmadou Gning
Amadou Gning
MSMarek Schikora
Marek Schikora
MUMartin Ulmke
Martin Ulmke
WKWolfgang Koch
Wolfgang Koch
Extended objects generate a variable number of multiple measurements. In contrast with point targets, extended objects are characterized with their size or volume, and orientation. Multiple object tracking is a notoriously challenging problem due to complexities caused by data association. This paper develops a box particle filter (box PF) method for multiple extended object tracking, and for the first time, it is shown how interval-based approaches can deal efficiently with data association problems and reduce the computational complexity of the data association. The box PF relies on the concept of a box particle. A box particle represents a random sample and occupies a controllable rectangular region of nonzero volume in the object state space. A theoretical proof of the generalized likelihood of the box PF for multiple extended objects is given based on a binomial expansion. Next, the performance of the box PF is evaluated using a challenging experiment with the appearance and disappearance of objects within the area of interest, with real laser rangefinder data. The box PF is compared with a state-of-the-art particle filter with point particles. Accurate and robust estimates are obtained with the box PF, both for the kinematic states and extent parameters, with significant reductions in computational complexity. The box PF reduction of computational time is atleast 32% compared with the particle filter working with point particles for the experiment presented. Another advantage of the box PF is its robustness to initialization uncertainty.

10 January 2025 in Discover Internet of Things
Verified
Journal Article
Open access
PDF file
RKRachel Kufakunesu
Rachel Kufakunesu
HMHerman Myburgh
Herman Myburgh
AFAllan De Freitas
Allan De Freitas
The use of Internet of Things (IoT) technology in military settings has introduced the notion of “Internet of Battle Things” (IoBT), transforming modern warfare by interconnecting various equipment and systems essential for battlefield operations. This connectivity facilitates real-time communication, data sharing, and collaboration among military assets, enhancing situational awareness, decision-making processes, and overall operational effectiveness. The domain for IoBT encompasses a broad range of military assets, from drones and ground vehicles to soldier-worn wearables, sensors, and munitions. These assets are capable of collecting and transmitting critical information from the battlefield, including location data, status updates, environmental conditions, and the movements of adversaries. IoBT networks depend on robust communication networks, secure data transmission protocols, advanced data analytics for processing vast datasets, and seamless integration with command-and-control infrastructures. However, IoBT devices and systems function in dynamic and challenging battlefield conditions which present unique communication challenges. This study aims to review research efforts that provide current state-of-the-art solutions, their limitations, and emerging technologies. We classify these challenges into interoperability, power and energy management, security, and network resilience, while also discussing future research directions to improve communication in IoBT networks.

8 November 2023 in Sensors
Verified
Journal Article
Open access
PDF file
GSGary Ian Summerfield
Gary Ian Summerfield
AFAllan De Freitas
Allan De Freitas
EMEste van Marle-Köster
Este van Marle-Köster
HMHerman Myburgh
Herman Myburgh
Body condition scoring is an objective scoring method used to evaluate the health of a cow by determining the amount of subcutaneous fat in a cow. Automated body condition scoring is becoming vital to large commercial dairy farms as it helps farmers score their cows more often and more consistently compared to manual scoring. A common approach to automated body condition scoring is to utilise a CNN-based model trained with data from a depth camera. The approaches presented in this paper make use of three depth cameras placed at different positions near the rear of a cow to train three independent CNNs. Ensemble modelling is used to combine the estimations of the three individual CNN models. The paper aims to test the performance impact of using ensemble modelling with the data from three separate depth cameras. The paper also looks at which of these three cameras and combinations thereof provide a good balance between computational cost and performance. The results of this study show that utilising the data from three depth cameras to train three separate models merged through ensemble modelling yields significantly improved automated body condition scoring accuracy compared to a single-depth camera and CNN model approach. This paper also explored the real-world performance of these models on embedded platforms by comparing the computational cost to the performance of the various models.

1 May 2024 in Expert Systems with Applications
Verified
Journal Article
Open access
ALAlexander Loubser
Alexander Loubser
JVJohan Pieter de Villiers
Johan Pieter de Villiers
AFAllan De Freitas
Allan De Freitas