University of Johannesburg

About: University of Johannesburg is a education organization based out in Johannesburg, South Africa. It is known for research contribution in the topics: Population & Context (language use). The organization has 8070 authors who have published 22749 publications receiving 329408 citations. The organization is also known as: UJ.

Removal of Escherichia coli and Faecal Coliforms from Surface Water and Groundwater by Household Water Treatment Devices/Systems: A Sustainable Solution for Improving Water Quality in Rural Communities of the Southern African Development Community Region

Abstract: There is significant evidence that household water treatment devices/systems (HWTS) are capable of dramatically improving microbially contaminated water quality. The purpose of this study was to examine five filters [(biosand filter-standard (BSF-S); biosand filter-zeolite (BSF-Z); bucket filter (BF); ceramic candle filter (CCF); and silver-impregnated porous pot (SIPP)] and evaluate their ability to improve the quality of drinking water at the household level. These HWTS were manufactured in the workshop of the Tshwane University of Technology and evaluated for efficiency to remove turbidity, faecal coliforms and Escherichia coli from multiple water source samples, using standard methods. The flow rates ranged from 0.05 L/h to 2.49 L/h for SIPP, 1 L/h to 4 L/h for CCF, 0.81 L/h to 6.84 L/h for BSF-S, 1.74 L/h to 19.2 L/h and 106.5 L/h to 160.5 L/h for BF The turbidity of the raw water samples ranged between 2.17 and 40.4 NTU. The average turbidity obtained after filtration ranged from 0.6 to 8 NTU (BSF-S), 1 to 4 NTU (BSF-Z), 2 to 11 NTU (BF), and from 0.6 to 7 NTU (CCF) and 0.7 to 1 NTU for SIPP. The BSF-S, BSF-Z and CCF removed 2 to 4 log10 (99% to 100%) of coliform bacteria, while the BF removed 1 to 3 log (90% to 99.9%) of these bacteria. The performance of the SIPP in removing turbidity and indicator bacteria (>5 log10, 100%) was significantly higher compared to that of the other HWTS (p < 0.05). The findings of this study indicate that the SIPP can be an effective and sustainable HWTS for the Southern African Development Community (SADC) rural communities, as it removed the total concentration of bacteria from test water, can be manufactured using locally available materials, and is easy to operate and to maintain.

Flow at Work: a Self-Determination Perspective

Abstract: Flow at work refers to a short-term peak experience that is characterized by absorption, work enjoyment, and intrinsic work motivation, and is positively related to various indicators of job performance. In an organizational context, research has predominantly focused on situational predictors of flow – including challenge job demands and resources. In this article, we propose that workers may also proactively create their own optimal experiences. We use self-determination theory to argue that all human beings have basic needs for autonomy, competence, and relatedness, as well as an inherent tendency towards proactivity and growth. We propose that workers may use four self-determination strategies to satisfy their basic needs, facilitate flow experiences, and, in turn, increase their job performance: self-leadership, job crafting, designing work to be playful, and strengths use. Furthermore, we argue that factors within the organizational context – such as human resource practices and leadership, as well as personal resources – such as self-efficacy and optimism, moderate the effectiveness of these strategies. Implications for theory, research, and practice are discussed.

Exponential Synchronization of Neural Networks With Time-Varying Delays via Dynamic Intermittent Output Feedback Control

Abstract: This paper addresses the exponential synchronization problem for neural networks with time-varying delays. First, a novel controller is presented by combining intermittent control with dynamic output feedback control. Next, a sufficient criterion is established based on the Lyapunov-Krasovskii functional approach and the lower bound lemma for reciprocally convex technique to ensure exponential stability of the resultant closed-loop system. Then, some solvable conditions of the proposed control problem are derived in terms of linear matrix inequalities. Notably, our results here extend the existing ones to the relaxed case because the derivative of time-varying delays is now an arbitrary bounded real number. Finally, a numerical simulation is provided to demonstrate the effectiveness of the proposed method.