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Pre-adoption motives for successful eLearning: A case study of socially deprived users in South Africa 成功电子学习的预采用动机:南非社会贫困用户的案例研究
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757699
Heiko Gewald, O. Jacob
{"title":"Pre-adoption motives for successful eLearning: A case study of socially deprived users in South Africa","authors":"Heiko Gewald, O. Jacob","doi":"10.1109/AFRCON.2013.6757699","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757699","url":null,"abstract":"This research analyses the adoption of an eLearning system by users without formal school education in infrastructurally weak areas. It is the first stage of an ongoing research project which will cover the system adoption over the next years. In this stage we examine the users' pre-adoption motives based on the eLearning adoption model put forward by Islam (2011) [1]. Based on the insights of a pre-study the model was adapted to reflect the specific context of this research project. Data was gathered through structured interviews with all prospective users. Based on their belief structures the expected satisfaction with the eLearning system was manifested. The findings provide grounds for assuming that the users will actually make good use of the system.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116518099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Some remarks on choosing video stream encoding for remote video verification on Android mobile devices 关于Android移动设备远程视频验证选择视频流编码的几点思考
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757671
Dariusz Mrozek, Bartlomiej Buk, Bożena Małysiak-Mrozek
{"title":"Some remarks on choosing video stream encoding for remote video verification on Android mobile devices","authors":"Dariusz Mrozek, Bartlomiej Buk, Bożena Małysiak-Mrozek","doi":"10.1109/AFRCON.2013.6757671","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757671","url":null,"abstract":"Video verification on mobile devices, such as cell phones and tablet PCs, allows users to remotely check what is happening in a particular place without the need to constantly monitor the site and record video from the camera. This requires appropriate stream encoding to be applied. Unfortunately, existing encoding standards, widely used in video monitoring, have several drawbacks. In the paper, we show some remarks on choosing video stream encoding for video verification on Android-based mobile devices. Results of performed tests on bandwidth usage have shown that encoding based on passing static frames in JPEG format translates very well into an environment where the camera's resolution is often higher than the mobile device screen.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126777893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Stability improvement of a HVDC transmission link between weak AC systems by multi-terminal scheme 多端方案提高弱交流系统间直流输电线路的稳定性
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757810
A. Nnachi, J. Munda, D. Nicolae, A. M. Mabwe
{"title":"Stability improvement of a HVDC transmission link between weak AC systems by multi-terminal scheme","authors":"A. Nnachi, J. Munda, D. Nicolae, A. M. Mabwe","doi":"10.1109/AFRCON.2013.6757810","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757810","url":null,"abstract":"But, the problem of voltage stability for weak AC systems interconnected by a DC link is critical especially during islanding conditions. The approach to improve more on the stability of such system would be to device a means of injecting locally controlled dc power on the dc-link transmission corridor forming a radial multi-terminal HVDC. However, continuous injection of DC power on the dc line of the VSC HVDC link though will increase the power transfer capability of the system but should have a limit otherwise it will lead to instability of the system. In this paper, a detailed VSC HVDC model and a simple analytical technique using the principle of uniform loading to determine penetration limit is presented. The techniques is applied to our case study and validated with a simulation result. Critical contingencies such as sudden island conditions, three-phase to ground fault are simulated with and without DC power penetration. Results show the stability support on the AC side networks by DC power injection on the dc-link.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127116187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Managing digital-system power at the system level 在系统级管理数字系统电源
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757781
Dominik Macko, K. Jelemenská
{"title":"Managing digital-system power at the system level","authors":"Dominik Macko, K. Jelemenská","doi":"10.1109/AFRCON.2013.6757781","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757781","url":null,"abstract":"The increasing trend in using mobile devices causes the power consumption to become the key aspect in modern digital systems design. The current flow for low-power design involves the use of some power-reduction technique at the RTL (Register Transfer Level) or lower levels. This paper describes an extension of current low-power design flow. It proposes the power-intent specification based on UPF (Unified Power Format) in an abstract form and integrates it into a system-level model. Such an abstract level gives us the opportunity to manage power with higher efficiency.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127131929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 13
Software system for expert systems learning 用于专家系统学习的软件系统
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757804
D. Drašković, B. Nikolić
{"title":"Software system for expert systems learning","authors":"D. Drašković, B. Nikolić","doi":"10.1109/AFRCON.2013.6757804","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757804","url":null,"abstract":"This paper describes a software system for expert systems learning realized at the School of Electrical Engineering at the University of Belgrade. This software has been developed as visual interactive educational system for students and is aimed to be used within undergraduate and graduate courses. The system guides students through examples and step-by-step tasks related to topics that represent a part of lectures and tutorials. The following topics are covered: breadth-first and depth-first strategies, hill-climbing method, best-first method, branch and bound methods, method A*, production systems, general problem solver, STRIPS planning system and undetermined environment operation systems - fuzzy logic, probability factor reasoning and other ways of expressing uncertainty, ID3 decision tree induction algorithm. Students may enter they own examples and tasks and thus obtain correct solutions. At every stage, it is possible to go backward or forward in the simulation. Student may also print the detailed how-to procedure of solving the task. The implemented system improves lecturer's efficiency and enhances knowledge acquisition of innovative curricula.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126248693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Comparison of distributed and lumped parameters stray current models 分布参数和集总参数杂散电流模型的比较
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757735
Fabio Fichera, A. Mariscotti, A. Ogunsola, L. Sandrolini
{"title":"Comparison of distributed and lumped parameters stray current models","authors":"Fabio Fichera, A. Mariscotti, A. Ogunsola, L. Sandrolini","doi":"10.1109/AFRCON.2013.6757735","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757735","url":null,"abstract":"DC electrified traction systems are a potential source of stray current, that may corrode both internal and external metal structures and installations. The stray current intensity depends on several factors (such as traction current, rail insulation, concrete mat and pier resistance) that need to be accounted for in any model for the estimation of stray current. The effect of an uniform or multilayer soil in such predictive model is of equal importance. In practice, there are numerous models that have been developed to investigate railway stray current phenomena; these models can be categorized into two - namely distributed parameter model and lump parameter model - based on the parameter model used. In this paper, both models are compared to highlight the differences between both methods.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124391421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
Weighted least squares and iteratively reweighted least squares comparison using Particle Swarm Optimization algorithm in solving power system state estimation 基于粒子群优化算法的加权最小二乘与迭代再加权最小二乘比较求解电力系统状态估计
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757730
D. H. Tungadio, B. Numbi, W. Siti, J. Jordaan
{"title":"Weighted least squares and iteratively reweighted least squares comparison using Particle Swarm Optimization algorithm in solving power system state estimation","authors":"D. H. Tungadio, B. Numbi, W. Siti, J. Jordaan","doi":"10.1109/AFRCON.2013.6757730","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757730","url":null,"abstract":"Measurements from the electrical network are generally transmitted towards the control centres using special communication links. These measurements allow determining the state of the network in real time. However, these measurements often contain uncertainties due to the meter and communication errors, incomplete metering or unavailability of some of these measurements, etc. This paper presents the application of the Particle Swarm Optimization (PSO) algorithm in minimizing the raw measurement errors in order to identify or estimate the optimal operating state of the power system. Two different objective function formulations are assessed by PSO. The first formulation is the Weighted Least Square (WLS) and the second one is the Iteratively Reweighted Least Squares (IRLS) implementation of the Weighted Least Absolute Value (WLAV). Both solutions are compared with a Newton-Raphson (NR) power flow solution using an IEEE 6-bus test system.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127571825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 9
Monitoring respiration by using fiber-optic interferomtery and maximum a posteriori estimation 利用光纤干涉仪和最大后验估计监测呼吸
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757750
D. Zazula, S. Sprager
{"title":"Monitoring respiration by using fiber-optic interferomtery and maximum a posteriori estimation","authors":"D. Zazula, S. Sprager","doi":"10.1109/AFRCON.2013.6757750","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757750","url":null,"abstract":"This paper reveals a novel approach to recognize respiration events by using an unobtrusive fiber-optic sensor. When the optical fiber is in a direct or indirect contact with human body, it detects weak contributions of vital signs. After a demodulation of fiber-optic signal, breathing can be sorted out by observing variations of heartbeat amplitudes. Introduced into a maximum a posteriori (MAP) estimation, it can locate time instants of inspirations and expirations. Estimates in experiments conducted after submaximal exercise tests in 14 young healthy subjects yield overall sensitivity 94.4±5.62% and overall precision 96.02±2.26% for inspirations. Overall mean absolute error of the inspiration onsets equals 260±143 ms. Similar figures apply to expirations.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"200 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133734122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
From tape reel to intercontinental lightpaths: Technical developments in the EVN 从磁带卷到洲际光路:EVN的技术发展
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757823
A. Szomoru, M. Lindqvist
{"title":"From tape reel to intercontinental lightpaths: Technical developments in the EVN","authors":"A. Szomoru, M. Lindqvist","doi":"10.1109/AFRCON.2013.6757823","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757823","url":null,"abstract":"This paper describes the recent developments in European Very Long Baseline Interferometry (VLBI), centered around the three themes of real-time e-VLBI, correlation and VLBI space science.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130809465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Vibration and noise analyses of canned switched reluctance machines with different winding topologies 不同绕组拓扑的屏蔽开关磁阻电机振动与噪声分析
2013 Africon Pub Date : 2013-09-01 DOI: 10.1109/AFRCON.2013.6757726
C. Laudensack, D. Gerling
{"title":"Vibration and noise analyses of canned switched reluctance machines with different winding topologies","authors":"C. Laudensack, D. Gerling","doi":"10.1109/AFRCON.2013.6757726","DOIUrl":"https://doi.org/10.1109/AFRCON.2013.6757726","url":null,"abstract":"Due to the fact of a simple and robust cross-section design switched reluctance machines are perfectly suited to drive hydraulic pumps; either as a dry-running version or as a canned version for seal-less applications. The can losses, additionally produced in the stator and rotor can shields of the seal-less version, usually count more than 60% of the total losses and have a big impact on the thermal behavior and stability of the switched reluctance drive. Different winding topologies for switched reluctance machines have also a big impact on the performance as well on the acoustic noise emission of the pump drive. The radial forces as well as the deformations and acoustic noise prediction of the stator structure are analyzed for different winding topologies used in canned switched reluctance machines.","PeriodicalId":159306,"journal":{"name":"2013 Africon","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131583974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
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