AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7331962
Ahmed Mehamed Oumer, A. Hunde
{"title":"Higher order sliding mode control of a parallel robot","authors":"Ahmed Mehamed Oumer, A. Hunde","doi":"10.1109/AFRCON.2015.7331962","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7331962","url":null,"abstract":"In this paper a two degree of freedom parallel robot is modeled using the principle of virtual work. In order to achieve smooth trajectory tracking a regularized third order sliding mode controller is developed. Simulation results show that steady state tracking is met in approximately 2 seconds for a circular trajectory of 300 mm radius. The maximum tracking error is shown to be 4mm. Chattering is eliminated and the closed loop system is also shown to be robust against external disturbances and mass uncertainties.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116714496","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7331928
S. D. Barnes, B. T. Maharaj
{"title":"Collaborative spectral opportunity forecasting for cognitive radio","authors":"S. D. Barnes, B. T. Maharaj","doi":"10.1109/AFRCON.2015.7331928","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7331928","url":null,"abstract":"Combining spectrum sensing (SS) and primary user (PU) traffic forecasting provides a cognitive radio network (CRN) with a platform from which informed and proactive operational decisions can be made. The success of these decisions is largely dependent on prediction accuracy. Since individual SUs may suffer from SS and prediction inaccuracies due to poor channel conditions, allowing secondary users (SU) to perform these predictions in a collaborative manner allows for an improvement in the accuracy of this process. A collaborative approach to forecasting PU traffic, that combines SS and forecasting through SU cooperation, was proposed in this paper. A sub-optimal cooperative forecasting algorithm was presented to minimise cooperative prediction error. The algorithm was used to investigate the cooperative prediction performance of a group of ten SUs experiencing different channel conditions. Simulation results indicated that cooperative prediction lead to a significant improvement in prediction accuracy and illustrated how diversity, both in terms of SS accuracy and individual prediction performance, can positively impact the prediction process.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124796604","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7332016
Temesgen A. Weseni, R. Watson, Salehu Anteneh
{"title":"A review of soft factors for adapting public-private partnerships to deliver public information services in Ethiopia: A conceptual framework","authors":"Temesgen A. Weseni, R. Watson, Salehu Anteneh","doi":"10.1109/AFRCON.2015.7332016","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7332016","url":null,"abstract":"Ethiopia, one of the poorest countries in the world, has been providing a haphazard and poorly structured Public Information Services (PISs) for decades. Effective PISs are channels of delivery of full-fledged digital information through electronic platforms from and to citizens on time. Accordingly, the Government has already recognized the role of Public-Private Partnerships (PPPs) to enhance sensitive PISs and realize its GTPs (Growth and Transformation Plans) despite the country's lack of clear regulatory framework of PPPs. A PPP is an agreement which could be signed by both the state and private sectors to deliver basic public demands on-time to citizens and PIS is a mode of implementing a digital and networked electronic service (e-Service) platform to citizens based on a common public interest. However, analyzing rigorously how to deliver basic PISs through PPPs and transform various state based sectors into an effective system has been an open question for the current Ethiopian practitioners. Through PPP, the private sector could play a role by contributing its flexible resources, expertise, and importing cutting-edge technologies thereby providing the rural and urban populaces with desired PISs. However, the readiness of the public sector to form partnerships with the private sector is minimal because establishing such a strong partnership is a complex phenomenon with several soft-factors including social and political. Being aware of this, the Ethiopian government has just started inspiring potential private sector actors in order to invest and improve the quality and delivery of basic PISs throughout the country. Although small in number, studies of other countries point out that many such initiatives tend to fail due to numerous causes. Furthermore, in developing countries, there are reported reality gaps, of various nature, regarding the impact of PPP initiatives as a mechanism to assuring the proper delivery of basic PISs. This study, therefore, is designed to analyze the soft factors of PPP initiatives that might help to adapt useful PPP models, relevant to the Ethiopian context, which ultimately help create successful, stable and quality PISs. A guiding theoretical foundation of this study is Soft-Systems Methodology (SSM). The study also intends to provide Ethiopian policy makers with a mechanism that will assist them to improve the delivery of basic PISs in the country.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124905679","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7331969
K. Ibrahim, R. Leidhold
{"title":"Variable frequency converter based voltage and frequency regulation of induction generator for stand-alone system application","authors":"K. Ibrahim, R. Leidhold","doi":"10.1109/AFRCON.2015.7331969","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7331969","url":null,"abstract":"Self-Excited Induction Generators (SEIG) exhibit a poor voltage and frequency regulation when subjected to load and speed changes. The proposed variable frequency converter (VFC) based Induction generator can provide constant frequency and almost constant voltage feeding ac loads in stand-alone systems without requiring fixed excitation capacitor and a special designed power electronics circuit. The system is designed using off-the-shelf products likes squirrel cage induction machine, an industrial VFC, a dump-resistor, a small LC-filter and a battery for starting up the system. The open loop vector mode operation of VFC provides constant V/f ratio except at low speed to keep the flux constant under varying load conditions. An external dumping load resistor is connected across the DC chopper to regulate varying consumer load. The proposed method has been carried out on a 50 Hz Induction machine with output power of 5.5kW and rated voltage of 400V in delta connection. The experimental result reveals that the proposed induction machine operation as Induction generator (IG) can be effectively used in a rural area to supply ac load with constant voltage and frequency with rated power delivery.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125933275","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7332054
Estifanos Yohannes, Dereje Hailemariam
{"title":"Joint adaptive modulation and adaptive MIMO system for fading channels in 3GPP LTE","authors":"Estifanos Yohannes, Dereje Hailemariam","doi":"10.1109/AFRCON.2015.7332054","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7332054","url":null,"abstract":"This paper presents joint adaptive modulation and multiple-input multiple-output (MIMO) system (JAMAMS) in Long Term Evolution (LTE) network that adapts both modulation type and MIMO scheme based on channel conditions. Specifically, four adaptive modulation-based MIMO techniques, namely, 1 × 2 MIMO with maximum ratio combining (MRC); 2 × 1 and 2 × 2 Alamouti techniques; and 2 × 2 Vertical Bell Labs Layered Space-Time Architecture (V-BLAST) are investigated. Bit error rate (BER) and spectral efficiency (SE) are used as performance metrics and Zero Forcing (ZF) detection is used in all the MIMO techniques. For each of the four techniques, first the signal-to-noise (SNR) thresholds for switching from one modulation order to the next (i.e., adaptive modulation) are determined. Then, based on comparison of the thresholds of the four schemes, a proposal is made when the system has to switch from one MIMO scheme to the other; and the resulting system is called JAMAMS. In the uplink scenario, as an example, adaptive modulation-based 2 × 2 Alamouti, 1 × 2 scheme with MRC, and 2 × 2 V-BLAST schemes have shown “optimal” SE performance in the SNR ranges 4-19 dB, 19 dB-28 dB, and greater than 28 dB, respectively, while satisfying target BER constraint, BERth ≤ 10-2. Moreover, it is shown that JAMAMS has comparable computational complexity in comparison to fixed MIMO systems.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126148344","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7331995
Fasil Alemeye, Fekade Getahun Taddesse
{"title":"Cloud readiness assessment framework and recommendation system","authors":"Fasil Alemeye, Fekade Getahun Taddesse","doi":"10.1109/AFRCON.2015.7331995","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7331995","url":null,"abstract":"Cloud computing is one of the fastest growing technologies. For developing countries like Ethiopia which has a growing ICT, cloud computing is an attractive choice to adopt. However, the adoption of such a technology should be planned ahead of time taking into consideration the various factors that make adoption successful. The main objective of this research is to propose a cloud readiness assessment framework and an expert system that assesses cloud readiness and recommend which cloud deployment and service model to adopt. The research is grounded by well-studied technological innovation adoption theories: Technology Organization Environment framework (TOE), Diffusion of Innovation (DOI) and Technology Acceptance Model (TAM). Based on these theoretical foundations, a new cloud readiness framework is proposed. A survey is designed based on the framework; using this survey an initial dataset is generated and expanded using synthetic data generator. The expert system relies on predictive modeling for assessing cloud readiness. So, using Weka machine learning platform, J48 decision tree algorithm is experimented using various settings, to train and obtain acceptable model accuracy. Training is performed on the original dataset and synthetically generated dataset. The best obtained model accuracy is 75% with the original dataset.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122327002","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7331998
H. B. Kassa, Dereje Hailemariam, Yacob Astatke, F. Moazzami, R. Dean
{"title":"Energy efficiency evaluation in downlink cellular communication networks","authors":"H. B. Kassa, Dereje Hailemariam, Yacob Astatke, F. Moazzami, R. Dean","doi":"10.1109/AFRCON.2015.7331998","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7331998","url":null,"abstract":"This paper investigates schemes that maximize energy efficiency in cellular networks. We derived the energy efficiency function in terms of system bandwidth, transmission success rate, constellation size, signal-to-noise ratio (SNR) and transmission power. Numerical results indicate that, the transmission success rate function will grow exponentially for an increase in SNR. As a result, the energy efficiency increases linearly when the transmit power is considered constant; however, it increases logarithmically when the transmit power increase proportionally with the system bandwidth. In addition, we showed that the energy efficiency maximization is not necessarily related to rate maximization and use of all available power. With a constant transmit power; the energy efficiency can be increased by 9dB for higher channel gains. Furthermore, it is shown that the energy efficiency can be maximized with a simultaneous increase of both system bandwidth and constellation size without maximizing the transmit power.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129515454","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7332039
B. Sousa, R. Millar, M. Lehtonen
{"title":"Influence of voltage sags and outage costs on realistic radial and backed-up 20-kV rural and urban networks","authors":"B. Sousa, R. Millar, M. Lehtonen","doi":"10.1109/AFRCON.2015.7332039","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7332039","url":null,"abstract":"This research investigates the cost burden of voltage sags and outages of two feeders in typical rural and urban environments in Finland, and compares the effect of different voltage sags on their adjacent feeders. The two tested feeders were each sampled from two 20-kV distribution networks generated by a Network Topology Optimizing Algorithm (NTOA) based on data from a rural area in Western Finland and from the metropolitan region of Helsinki. This study divides the base year into four seasons and considers load data, features and constraints intrinsic to the local scenarios. As inputs to the cost assessment, the reliability technique estimates important reliability indices at each substation. The residual voltages during contingencies, analytically obtained, define the voltage sag rates at several points of the feeders under focus. As main conclusions, voltage sag costs in the simulated feeders are significantly smaller than the outage costs, but voltage sags originating in certain zones of these feeders directly affect voltage levels in other adjacent feeders and upstream equipment, thus propagating the economic burden to other parts of this network.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124630696","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7331860
A. A. Ahmad, John B. Ayeni, S. M. Kamal
{"title":"Determination of the pulse repetition interval (PRI) agility of an incoming radar emitter signal using instantaneous power analysis","authors":"A. A. Ahmad, John B. Ayeni, S. M. Kamal","doi":"10.1109/AFRCON.2015.7331860","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7331860","url":null,"abstract":"Determining the level of pulse repetition interval (PRI) agility is important in the field of Electronic Intelligence (ELINT) in order to provide warning receiver and jammers with the appropriate information in order to take action. This paper uses smoothed instantaneous power in order to estimate the PRIs of an incoming radar emitter signal. The test signals considered for this work is made up of simple pulsed and staggered PRI radar signal of various intervals and position. The algorithm designed uses the Hilbert transform to obtain the analytic version of the incoming signal before the Hamming smoothed instantaneous power is applied to the signal. Thereafter, first, second and third PRI are obtained and used to form rules for the rule-based Classifier. The rule-based classifier classifies the signals in order to determine the level of PRI agility. Performance analysis is carried out in the presence of additive white Gaussian noise (AWGN) for 100 iterations. Results obtained showed that a 100 percent probability of correct classification is obtained at signal-to-noise ratio (SNR) equal or greater than 3dB irrespective of the incoming signal.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129035376","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}
AFRICON 2015Pub Date : 2015-11-19DOI: 10.1109/AFRCON.2015.7332051
M. Rahman, Tom Walingo, F. Takawira
{"title":"Adaptive handover scheme for LEO satellite communication system","authors":"M. Rahman, Tom Walingo, F. Takawira","doi":"10.1109/AFRCON.2015.7332051","DOIUrl":"https://doi.org/10.1109/AFRCON.2015.7332051","url":null,"abstract":"Low Earth Orbit (LEO) satellites have appealing characteristics that make them most adequate for the provision of ubiquitous wireless service. However, frequently occurring handover across satellite spot beams (due to the high mobility of LEO satellites) is a serious shortfall that needs to be addressed. Handover management issues are solved by an efficient handover algorithm and proper resource allocation. An Adaptive Handover Scheme (AHS) is proposed to address handover issues in LEO satellite networks. The proposed scheme, utilizes a resource allocation strategy that considers the varying characteristics of the wireless channel. Furthermore, AHS provides users with improved Quality of Service (QoS) by keeping Connection Blocking Probability (CBP) and Connection Dropping Probability (CDP) at an acceptable level. The performance results of the developed handover algorithm show an improvement in the CDP and CBP of new and handover connections.","PeriodicalId":347759,"journal":{"name":"AFRICON 2015","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114793457","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}