Molaletsa Namoshe | Botswana International University of Science & Technology (original) (raw)

Papers by Molaletsa Namoshe

Data in Brief, 2019

The conventional soft solder used in soldering electronic joints is made up of 63% Sn and 37% Pb.... more The conventional soft solder used in soldering electronic joints is made up of 63% Sn and 37% Pb. It has been established that Pb is harmful to the body. Therefore, there is an ongoing research to find a replacement for Pb. AleZneSn alloy is considered here as a possible replacement for soft solder of Sn and Pb. Three compositions of the alloy (Ale7Zne3Sn, Ale10Zne5Sn, and Ale13Zne7Sn) were sintered at the sintering temperatures of 300 C and 350 C (and the constant pressure of 40 MPa, time of 5 mins, a heating rate of 20 C/mins). Temperature/displacement/time variation data during the sintering were collected. The three alloys were compared after sintering by checking their microstructure, their densities, their hardness, their porosity, and their tensile strengths. Results showed that Ale13Z-ne7Sn sintered at 350 C, 40 MPa, 5 mins, 20 C/mins had the highest densification of 99.7%, the lowest porosity of 0.3%, least hardness and strength of 450.34 MPa and 147.84 MPa respectively.

International Journal of Biological Macromolecules

Data Science Journal, 2021

The Southern African Science Service Centre for Climate and Land Management (SASSCAL) was initiat... more The Southern African Science Service Centre for Climate and Land Management (SASSCAL) was initiated to support regional weather monitoring and climate research in Southern Africa. As a result, several Automatic Weather Stations (AWSs) were implemented to provide numerical weather data within the collaborating countries. Meanwhile, access to the SASSCAL weather data is limited to a number of records that are achieved via a series of clicks. Currently, end users can not efficaciously extract the desired weather values. Thus, the data is not fully utilised by end users. This work contributes with an open source Web Scraping Application Programming Interface (WebSAPI) through an interactive dashboard. The objective is to extend functionalities of the SASSCAL Weathernet for: data extraction, statistical data analysis and visualisation. The SASSCAL WebSAPI was developed using the R statistical environment. It deploys web scraping and data wrangling techniques to support access to SASSCAL weather data. This WebSAPI reduces the risk of human error, and the researcher's effort of generating desired data sets. The proposed framework for the SASSCAL WebSAPI can be modified for other weather data banks while taking into consideration the legality and ethics of the toolkit.

American Journal of Engineering and Applied Sciences, 2017

Botswana's beef sector contributes 0.3% of the total world beef exports, i.e. US$ 42.4 billion as... more Botswana's beef sector contributes 0.3% of the total world beef exports, i.e. US$ 42.4 billion as of the year 2013 and her major market is the European Union (EU). Unfortunately, her failure to comply with the frequently changing European Commission (EC) export regulations on livestock tracking and identification means that beef export to this market is sometimes suspended. Research trends indicate that smart agriculture solutions have gained popularity in agricultural production and can help keep up with the frequently changing EC export regulations especially on active tracking and identification of livestock. It is against this background that this paper presents the development of electronic control circuits for Wireless Sensor Network (WSN) and Group Special Messaging (GSM) to be utilized in a livestock tracking and identification system. It is envisaged that the proposed solution would help fulfill potential changes of EC regulations. Proteus 8 software is used to develop the circuit models. The controller used for this work is Arduino microcontroller. Simulation results show that the XBee shields are able to communicate successfully. This communication forms the basis for the WSN. The results indicate that the developed electronic control circuits for the WSN are viable. Future work will focus on the development of a prototype that will be tested and validated in real environment.

Most real systems are non-linear. Extended Kalman Filter (EKF) uses non-linear models of both the... more Most real systems are non-linear. Extended Kalman Filter (EKF) uses non-linear models of both the process and observation models while the Kalman Filter (KF) uses linear models. EKF is a good way to learn about Simultaneous Localisation and Mapping (SLAM). Much of the literature concentrates on advanced SLAM methods which stems from EKF or uses probabilistic techniques. This makes it difficult for new researchers to understand the basics of this exciting area of research. SLAM asks if it is possible for a robot, starting with no prior information, to move through its environment and build a consistent map of the entire environment. Additionally, the vehicle must be able to use the map to navigate and hence plan and control its trajectory during the mapping process. The applications of a robot capable of navigating, with no prior map, are diverse indeed. Domains in which 'man in the loop' systems are impractical or difficult such as sub-sea surveys and disaster zones are obvi...

Botswana citizens experience energy shortage especially at the rural areas where grid transmissio... more Botswana citizens experience energy shortage especially at the rural areas where grid transmission is not accessible. Therefore, rural dwellers find it difficult to use their gadgets and sometimes they are compelled to travel to nearby places or towns in order to get electricity. Sun energy is available and is a cheaper alternative that could be used to address the problem of power accessibility especially in remote areas. Photovoltaic panels are normally used to harvest the solar energy however they generate a DC electrical signal but majority of modern appliances use AC voltage signal. A power inverter is used to convert DC voltage signal to AC signal, suitable for most house hold appliances. The conversion principle output rely on how efficient the converter is, in terms of losses. The aim of this paper is to compare three (3) different circuits modeled via PSIM software in terms of their efficiency, cost and complexity of circuit construction. The PSIM software uses inbuilt gate...

Abst rac t-Open source software simulators play a major role in robotics design and research as p... more Abst rac t-Open source software simulators play a major role in robotics design and research as platforms for developing, testing and improving architectures, concepts and algorithms for cooperative/multi-robot systems. Simulation environment enables control systems to be developed rapidly and transferred to the real system with minimal change in behaviour. A number of simulators boost of effective data flow between sensors, processors and actuators of a robot/ team through a communication channel. The drive to build an adaptable and capable robotic development environment has led to the emergence of numerous open source application programs. This article discusses freely available open source simulators and their impact in multi mobile robot system research projects. Firstly, the architectures of the different simulation software are discussed. Secondly, their capabilities are discussed with regards to their architectures. Thirdly, multi-robot cooperation theory is presented. Lastly, an example of algorithm development for multi-robot cooperation using one of the discussed simulation platforms is presented.

2021 Southern African Universities Power Engineering Conference/Robotics and Mechatronics/Pattern Recognition Association of South Africa (SAUPEC/RobMech/PRASA), 2021

To do away with the time consuming, error prone and expert dependent gold detection and localizat... more To do away with the time consuming, error prone and expert dependent gold detection and localization in the current gold panning procedure, automatic image-based techniques are considered in this paper. Identifying and locating gold particles during the gold panning process is a fundamental process in gold extraction. In the automation of the gold panning process and robotic handling it is important to identify and locate the gold particles in the images captured by the image sensor. Image segmentation is a vital step in image simplification, image understanding and object detection. Image segmentation is the process of identifying and extracting homogeneous regions (segments) in an image satisfying a homogeneity criterion based on features formulated from spectral components of the image. Three image thresholding techniques were tested and evaluated on sample gold panning images. Color image thresholding in the CIELAB color space performed better in detecting and locating gold particles in an image. The proposed method will serve as a front-end technique for an automated gold panning system as it will automate the visual feature identification of gold particles and aid in the control of the handling system of the gold particles during the panning process.

International Journal of Dynamics and Control, 2020

This paper presents a literature review on current studies in cooperative control of fixed-wing d... more This paper presents a literature review on current studies in cooperative control of fixed-wing drones, including maneuvering through adjustments of the tail, rotor, and wing configurations. Cooperative fixed-wing drones are important because of their larger area coverage that allows them to complete the assigned task much faster compared to a single fixed-wing drone. In addition, the endurance of cooperative fixed-wing drones is much higher compared to the endurance of cooperative multirotor drones. The papers presented in this review were selected to have as wide a variety as possible in terms of cooperation architectures and strategies, as well as in terms of wing, tail, and rotor configurations. With the rapid advancement of computers, sensors, and actuators which are major components of drones in general, the advancement of fixed-wing drone technology is a logical consequence. And further, this can lead to the advancement of cooperative fixed wing drone which have a much bigger capability compared to a single UAV. Keywords Fixed-wing drones • cooperative control • wing, rotor, and tail configurations • maneuverability • critical review • cooperation strategies.

American Journal of Engineering and Applied Sciences, Apr 1, 2017

Smart technology and Internet of Things (IoT) applications have gained popularity in the developm... more Smart technology and Internet of Things (IoT) applications have gained popularity in the development of agricultural systems with Wireless Sensor Networks (WSNs) increasingly becoming the building blocks for IoT applications. However, WSNs have a limited power supply. As a result, these systems have a short lifespan, limited memory and low computing power. This paper describes the development of a hybrid power module for WSN to be utilized in a livestock tracking and identification system. Mathematical and MATLAB-Simulink models are developed and used to simulate the characteristics of a lithium ion (Liion) battery; to power the mobile sensor node (eartag), a nickel metal hydrate (NimH) battery used to power the static sensor nodes, a solar cell and the hybrid power module. Simulation results show that individually, the power sources provide limited power but the hybrid system coupled with a switching block generates enough power for the system, this implies that the system is viable but a prolonged operation of the system will depend on the battery limitations and climatic conditions. Future work will focus on the development of a prototype that can be tested and validated in real environment.

Procedia Manufacturing, 2017

Abstract Environmental friendly pre-treatment of fibre has been lately adopted by many researcher... more Abstract Environmental friendly pre-treatment of fibre has been lately adopted by many researchers worldwide but not fully understood. Although various chemical modifications of fibre through several chemical treatments have been explored, but less has been done on lower sodium hydroxide (NaOH) concentrations. This paper investigated the effect of thermalization at 115 C and lower NaOH of concentrations (1, 3 and 5) effect on mukwa wood flour as a way of minimizing chemical impact on possible manufacturing of eco-friendly wood polymer composites (WPC). Weight loss analysis was carried out to evaluate the effect of thermalization and alkalization modification. X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to characterize the untreated and treated mukwa wood flour. The results showed significant surface modification thereby improving fibre characteristics as impurities (hemicellulose, lignin and other non-cellulosic substances) were removed.

2008 15th International Conference on Mechatronics and Machine Vision in Practice, 2008

Despite advances in recent years, autonomous multirobot systems remain classed as complex systems... more Despite advances in recent years, autonomous multirobot systems remain classed as complex systems, because control and coordination of these systems remain a challenging task. Autonomous mobile robot houses heterogeneous sets of connected modular devices and are expected to communicate both synchronously and asynchronously. Robot complexities make the development of components for robot applications nontrivial and failure prone exercise. In trying to find a solution to the problem efficient modular interaction, robot software "Middleware" emerged. Middleware is software layer that provides an infrastructure for integration of applications and data in distributed systems domain. This article discusses freely available middleware for robotics and their technologies within the field of multi-robot systems to ease the difficulty of realizing robot applications. And lastly, an example of algorithm development for multi-robot cooperation using one of the discussed software architecture is presented.

ing and non-profit use of the material is permitted with credit to the source. Statements and opi... more ing and non-profit use of the material is permitted with credit to the source. Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published articles. Publisher assumes no responsibility liability for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained inside. After this work has been published by the In-Teh, authors have the right to republish it, in whole or part, in any publication of which they are an author or editor, and the make other personal use of the work.

Procedia Manufacturing, 2019

The desire for advanced performing renewable materials and friendly to the environment has grown ... more The desire for advanced performing renewable materials and friendly to the environment has grown worldwide. Lignocellulosic materials have demonstrated great potential as reinforcing agents in the manufacturing of composite materials. Achieving such materials also depends on the optimization of parameters not limited to particle size, temperature, duration of treatment, manufacturing technique and the type of modification. Laccase enzyme, a biological modification deemed friendly to the environment with the aid of alkali pre-treatment was adopted for removal of hemicellulose and lignin that binds the cellulose fibres together. In this paper, particle sizes between; +100-200 µm, +200-300 µm, +300-425 µm, and +425-710 µm were immersed in 5wt% sodium hydroxide (NaOH) concentration followed by laccase modification. The enzyme activity, temperature and soaking duration were kept constant. The effects resulting from the modifications on the above particle sizes of waste mukwa were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and weight loss assessment. Significant improvements were observed on the untreated fibres. The morphology of modified fibres showed small differences while the crystallinity index revealed noticeable differences between the particle sizes. The surface modifications reduced the weight of the overall particles as impurities were extracted and influenced some functional groups; hydroxyl (-OH), lignin, cellulose, and hemicellulose. An improvement was also observed on the thermal stability of the treated fibres. The modifications were more effective on particle size +100-200 μm followed by +200-300 μm while the coarse particles did not show much improvement.

Simultaneous Localisation and Mapping (SLAM) is a process by which a mobile robot maps the enviro... more Simultaneous Localisation and Mapping (SLAM) is a process by which a mobile robot maps the environment and concurrently localises itself within the map. Feature extraction is a technique by which sensor data is processed to obtain well defined entities (features) which are recognisable and can be repeatedly detected. These features are then used to aid navigation. In this paper, Mechanically Scanned Imaging Sonar (MSIS) is used to perform scans of the environment. The information returned is then used to detect point features from data collected in a swimming pool. Artificial landmarks were introduced into the environment to obtain identifiable and stable features. This work is part of our efforts to develop a SLAM system to be utilised in an Autonomous Underwater Vehicle (AUV).

Robot Localization and Map Building, 2010

A robot is said to be fully autonomous if it is able to build a navigation map. The map is a repr... more A robot is said to be fully autonomous if it is able to build a navigation map. The map is a representation of a robot surroundings modelled as 2D geometric features extracted from a proximity sensor like laser. It provides succinct space description that is convenient for environment mapping via data association. In most cases these environments are not known prior, hence maps needs to be generated automatically. This makes feature based SLAM algorithms attractive and a non trivial problems. These maps play a pivotal role in robotics since they support various tasks such as mission planning and localization. For decades, the latter has received intense scrutiny from the robotic community. The emergence of stochastic map proposed by seminal papers of (Smith et al., 1986; Moutarlier et al., 1989a; Moutarlier et al., 1989b & Smith et al., 1985), however, saw the birth of joint posterior estimation. This is a complex problem of jointly estimating the robot’s pose and the map of the env...

Mobile robot operation in an un-surveyed environment presents a challenging problem, particularly... more Mobile robot operation in an un-surveyed environment presents a challenging problem, particularly in GPS denied spaces. The complexity of the problem scales up if the sensor used to aid navigation can only provide range information about the features in that environment. In the past, almost all solutions to Localization problems relied on a prior knowledge of feature locations. In this paper however, range measurements, characteristically known to have outliers and unobservable are used to solve the localization problem. Past approaches to this problem have used delayed initialization of newly observed feature(s) until good estimates are available; a process akin to Hough transforms methods. This ratio thresholding approach has shown to be susceptible to system divergence, especially when large environments are explored. In this paper therefore, a pose disambiguating algorithms comprising of outlier rejection, particle swam optimization (PSO) and an area under a probability distribu...

Sensor Fusion and its Applications, 2010

Accurate and reliable maps generated autonomously guarantees improved localization especially in ... more Accurate and reliable maps generated autonomously guarantees improved localization especially in GPS denied surroundings like indoor (Hough, P.V.C, 1959). The use of odometry is not sufficient for position estimation due unbounded position errors. Therefore, since office like environments consists of planar surfaces, a 2D space model is adequate to describe the robot surroundings because objects are predominantly straight line segments and right angle corners. Coincidentally, line segments and corner representation are the two most popular methods for indoor modelling from a laser rangefinder. The focus in this paper however is corner extraction methods. A number of line and corner extraction techniques first transform scan data into Cartesian space then a linear regression method or corner extraction algorithm is applied. Some algorithms employ Hugh transform (Hough, P.V.C, 1959). & (Duda, R. O, 1972) a popular tool for line detection from scan data due to its robustness to noise and missing data. It works in sensor measurement space. However, the computational cost associated to its voting mechanism renders real-time implementation impossible. On the other hand, an early work by (Crowley, J, 1989) paved the way to subsequent line extraction methods from a range sensor. In their work, a process for extracting line segments from adjacent co-linear range measurements was presented. The Kalman filter update equations were developed to permit the correspondence of a line segment to the model to be applied as a correction to estimated position. The approach was recently extended by (Pfister, S.T et al. 2003), first providing an accurate means to fit a line segment to a set of uncertain points via maximum likelihood formalism. Then weights were derived from sensor noise models such that each point's influence on the fit is according to its uncertainty. Another interesting work is one by (Roumeliotis & Bekey, 2000), where two Extended Kalman filters are used to extract lines from the scan data. In the algorithm, one Kalman filter is used to track the line segments while the other estimates line parameters. The combination of the two filters makes it possible to detect edges and straight line segments within the sensor field of view. There are many features types one can extract from a laser sensor, and are dependent on the obstacles found in the room. If the room has chair and table, one would be tempted to extract point features from their legs. Size, shape and texture of objects contribute to the type of feature to extract from the sensor. The use of generalised algorithms is not uncommon, i.e. algorithms which extract lines from wall, point features from table legs and arcs to categorise circular objects (Mendes, & Nunes, 2004). The parameters that distinguish each extracted feature makes up the map or state estimate. The key to a successful robot pose estimation lies in its ability to effectively extract useful information about its location from observations (Li & Jilkov, 2003). Therefore we proposed an improved corner detection method to reduce computational cost and improved robustness. The paper is structured as follows; section 2 deals with feature extraction, section 3 discuss the EKF-SLAM process. Section 4 is result and analysis, while section 5 covers conclusion and future work.