Student perception on a supplementary multimodal tool for Academic Literacy: A pilot study

In light of the various advantages the e-learning experience could have for students, a blended teaching approach, where instructors make use of e-learning, has become increasingly prominent in higher education institutions. This study, which was conducted at a South African institute of higher education with a diverse and multilingual student population, focusses on student perceptions of theefficacy and accessibility of a multimodal tool called WIReD to supplement the existing academic literacy module. The review of student perceptions was structured around the outcomes for the module unit with which WIReD is intended to blend. In order to determine student perception, a questionnaire using a Likert-scale to measure responses along with open-ended questions, were used. As such, this study firstly examined students’ impressions of the design (overall appearance) and accessibility of WIReD. Secondly, it  investigated the appropriateness of content, especially with regard to the envisaged blend between WIReD and the module contentas taught during lectures and in the workbook. Despite being a pilot study with results based exclusively on student perception, it seems that WIReD can be utilized as a supplementary multimodal tool and that the outcomes thereof blends effectively with the outcomes of the academic literacy module. Keywords: academic literacy; blended learning; e-learning; multimodal teaching tool; student perception; WIRe

A Review of the Topologies Used in Smart Water Meter Networks: A Wireless Sensor Network Application

This paper presents several proposed and existing smart utility meter systems as well as their communication networks to identify the challenges of creating scalable smart water meter networks. Network simulations are performed on 3 network topologies (star, tree, and mesh) to determine their suitability for smart water meter networks. The simulations found that once a number of nodes threshold is exceeded the network’s delay increases dramatically regardless of implemented topology. This threshold is at a relatively low number of nodes (50) and the use of network topologies such as tree or mesh helps alleviate this problem and results in lower network delays. Further simulations found that the successful transmission of application layer packets in a 70-end node tree network can be improved by 212% when end nodes only transmit data to their nearest router node. The relationship between packet success rate and different packet sizes was also investigated and reducing the packet size with a factor of 16 resulted in either 156% or 300% increases in the amount of successfully received packets depending on the network setup

Improving the sustainability of confirmed traffic in LoRaWANs through an adaptive congestion scheme

The scalability of long-range wide area networks (LoRaWANs) is known to be very sensitive to the presence of traffic from gateways (GWs) to end devices (downlink (DL) traffic). The protocol supports confirmed traffic, for which DL traffic is generated in the form of acknowledgments (ACKs). Research has shown that even a limited number of ACKs quickly cause network congestion, negatively impacting scalability. This article introduces a mechanism, the adaptive congestion scheme (ACS), which aims to monitor the congestion caused by DL traffic and take steps to reduce it. Currently, the ACS supports one counteraction in the form of a newly developed algorithm called groupedPackets (also introduced in this article). This algorithm reduces the number of sent confirmed packets by requesting that confirmed nodes (nodes that only send confirmed traffic) aggregate their application packets. Simulations showed that this algorithm improved the successful delivery of both unconfirmed traffic and confirmed traffic. When traffic volumes are low, the algorithm has a minimal impact, but at high network packet arrival rates (higher than 0.1 pkt/s), the successful delivery of especially confirmed traffic increased significantly.The Council for Scientific and Industrial Research, Pretoria, South Africa, through the Smart Networks collaboration initiative and IoT-Factory Program (Funded by the Department of Science and Innovation (DSI), South Africa). This work is based on the research supported in part by our industry partner Telkom.https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=7361hj2023Electrical, Electronic and Computer Engineerin

A survey on the viability of confirmed traffic in a LoRaWAN

Internet of Things (IoT) deployments are on the rise globally with Low Power Wide Area Networks (LPWAN) providing the wireless networks needed for this expansion. One of these technologies namely Long Range Wide Area Network (LoRaWAN) has proven to be a very popular choice. The LoRaWAN protocol allows for confirmed traffic from the end device to the gateway (uplink) and the reverse (downlink), increasing the number of IoT use cases that it can support. However, this comes at a cost as downlink traffic severely impacts scalability due to in part a gateway's duty cycle restrictions. This paper highlights some of the use cases that require confirmed traffic, examines the recent works focused on LoRaWAN confirmed traffic and discusses the mechanism with which is implemented. It was found that confirmed traffic is viable in small networks, especially when data transfer is infrequent. Additionally, the following aspects negatively impact the viability of confirmed traffic in large networks: the duty cycle restrictions placed on gateways, the use of spreading factor 12 for receive window 2 transmissions, a high maximum number of transmissions (NbTrans) and the ACK_TIMEOUT transmission backoff interval. The paper also raises and suggests solutions to open research challenges that must be overcome to increase the viability of confirmed traffic.The Council for Scientific and Industrial Research of South Africa and Telkom.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=6287639am2020Electrical, Electronic and Computer Engineerin

Migration patterns and survival of Busseola fusca larvae in maize plantings with different ratios of Bt and non–Bt seed

MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014The high-dose/refuge strategy is used globally to manage insect resistance development in genetically modified crops with insecticidal properties (Bt crops). The “refuge in a bag” (RIB) strategy is also being considered for deployment against several pest species. Busseola fusca, the target pest of Bt maize in South Africa, evolved resistance to Cry1Ab proteins. The objective of this study was to determine whether migrating B. fusca larvae are effectively controlled using the RIB strategy. A field study with a single-gene event (Cry1Ab) and a “pyramid” event (Cry1A.105 + Cry2Ab2) was conducted in which the migration patterns of B. fusca larvae in plots with different seed mixture treatments were studied. The experiment consisted of five seed mixture ratios (5%, 10%, 15%, 20% non-Bt seed and 100 % non-Bt seed as control). Natural infestation was augmented by artificial inoculation with neonate larvae into the central non-Bt maize plant of each plot. Rate of larval survival and migration, measured in terms of increase in number of plants per plot that exhibited borer damage was recorded at weekly intervals until flowering. A laboratory study was conducted to determine larval growth and survival when simulating migration between Bt and non-Bt maize plants. A feeding experiment in which larvae were reared on different types of maize (Bt and non-Bt) was conducted and larval survival and mass recorded after a 7-day feeding period. The incidence of damaged ears, stem damage and damaged internodes per stem were recorded and relationships between these variables determined by means of correlation analyses. A review was conducted in order to identify and discuss similarities and differences between the high-dose/refuge and seed mixture strategies. This was done to determine which strategy would be the most appropriate insect resistance management (IRM) strategy against B. fusca. The rate of survival and migration of B. fusca larvae was significantly higher in the plots with maize expressing Cry1Ab and control plots, than in plots with the pyramid Bt event. Older larvae exhibited improved growth and survival in the laboratory experiment when they were transferred from non-Bt to Bt plants. Positive correlations were found between early and late season damage, although some weaker than others. Plants of the “pyramid event” suffered less late-season damage than those of the single-gene event. Since the increase in number of damaged maize plants over time is associated with migration of older and larger larvae, the observed tendencies may indicate that the assumed high-dose does not kill larvae above a certain developmental stage. The high-dose refuge strategy seems to be the better option for delaying resistance development.Master

Construction and performance evaluation of a LoRaWAN testbed

The Internet of Things (IoT) is the creation of a large network of interconnected devices that can communicate wirelessly to enable innovation across multiple fields. A newly developed wireless technology is the Long Range Wide Area Network (LoRaWAN) protocol and the performance of LoRaWANs is the focus of this work. Literature revealed that existing performance evaluations were mainly performed over short time periods and with only a few nodes. Additionally, communication was only evaluated over short distances in urban areas and long distance evaluations were mainly performed in rural environments. A research gap, therefore, existed for the evaluation of this technology over long and short distances and over long time periods in an urban environment. The contributions of this research can be laid out as three objectives. The first was to determine how effective a LoRaWAN would be for nodes at larger distances (> 1.5km) from a gateway in an urban environment. The second was to determine how the Adaptive Data Rate (ADR) scheme impacts the performance of a LoRaWAN. The final objective was to determine the impact of other LoRaWAN parameters on the performance of a LoRaWAN. A LoRaWAN testbed was constructed consisting of 18 nodes and one gateway, and several experiments were performed. Each node was sent configuration commands remotely and each experiment was executed until every node sent 1000 packets. Packet delivery in the form of the Packet Delivery Ratio (PDR) was chosen as the performance metric to be used and this was calculated from the ratio of sent versus received packets. The first objective was to examine LoRaWAN performance from the perspective of long range nodes. This was answered by examining the data from 5 nodes, located at distances between 1.98 km and 5.19 km from the gateway. The results show that a LoRaWAN should only be used if a PDR of between 60~\% and 80 \% is acceptable for long range nodes. Furthermore, there can be significant differences in the PDRs between nodes and these differences can become bigger over long distances. The data revealed that all aspects, but especially the ADR scheme, should be considered for long range nodes. The LoRaWAN protocol's ADR scheme was the focus of the second research contribution. This scheme aims to optimise network throughput by adjusting the transmission settings of individual nodes in the network. When the ADR scheme was enabled, the PDR was consistently worse for all three groups (the 18 nodes were divided into three groups based on distance). An examination of the data revealed that, out of 5 possible data rates, the scheme dominantly assigned either the slowest or the fastest data rate. The slower data rates allow for greater range, but the scheme algorithm did not assign these rates to nodes at longer distances, and as a result their performance suffered. The data also revealed that the data rate assignments oscillated between choices, forcing nodes to switch between rates very frequently. The last research contribution was to determine the impact of other LoRaWAN parameters on the performance of a LoRaWAN. There are numerous parameters and combinations, and thus only the impact of payload length, link checks and waiting time on the PDR were examined and these were found to be not significant. The evaluation of enabling acknowledgements did reveal a significant improvement to the PDR, but whilst this feature works well in small networks (such as the testbed), it would be detrimental in large networks. LoRaWAN gateways can either be in receiving or transmitting mode and gateways are unable to receive packets when transmitting acknowledgements, therefore resulting in an increase in missed packets for a gateway in a large and congested network.Dissertation (MEng)--University of Pretoria, 2018.Electrical, Electronic and Computer EngineeringMEng (Computer Engineering)Unrestricte

A Cloud-Based Road Infrastructure Analysis System using Machine Learning

A cloud-based road infrastructure analysis system was developed to assist as an information management system for detecting and managing information about road defects and road assets. The system uses computer vision and machine learning algorithms and is accessed through a web interface. The detection results are viewed through an online, account-based web interface

Evaluating the LoRaWAN protocol using a permanent outdoor testbed

Low-power wide-area network (LPWAN) protocols, such as a long range wide area network (LoRaWAN), are key to ensuring scalable wireless communication for Internet of Things devices. In this paper, an analysis of this protocol through a performance evaluation of a permanent outdoor LoRaWAN tested is presented. To ensure accurate results, tests lasted at least 17 h and required 1000 packets per node. The evaluation focused on the impact that the adaptive data rate (ADR) scheme, payload length, link checks, and acknowledgements had on the packet delivery ratio (PDR) of the testbed. The collected data showed that enabling the ADR scheme reduced the PDR. The ADR scheme had six data rates, which consist of a spreading factor and bandwidth combination, to choose from. Analysis revealed that the scheme primarily assigning either the fastest data rate (SF7BW250) or the slowest (SF12BW125) to nodes, regardless of distance. Furthermore, the scheme's assignments show the signs of oscillation, with nodes being instructed to abruptly change between SFs. The impact of payload length and link checks on the PDR was not pronounced, but enabling acknowledgements did show significant improvements.https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=7361hj2019Electrical, Electronic and Computer Engineerin