Browsing by Author "Mvungi, Nerey H."
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Item Active Learning through Smart Grid Model Site in Challenge Based Learning Course(Journal of Systemics, Cybernetics and Informatics, 2018-10) Kalinga, Ellen A.; Ibwe, Kwame S.; Mvungi, Nerey H.; Tenhunen, HannuSmart Grid is a new and growing technology to developing countries. Its implementation and sustainability rely on well trained experts. Sustainability of the smart grid need local experts, hence a project named iGRID: Smart Grid Capacity Development and Enhancement in Tanzania was started. The project is running at the College of Information and Communication Technologies, University of Dar es Salaam. It intends to generate the necessary technical and scientific skills to ensure sustainable implementation of smart grid. iGRID project introduced taught PhD and Masters programs focusing on society, innovation and entrepreneurship in iGRID aspects, as well as to facilitate implementation of automation of monitoring, evaluation, analysis, control and management of electrical power system (smart grid) in order to improve delivery efficiency and to optimize operational costs in the electrical power system in Tanzania. The project made use of Challenge-Based Learning (CBL) methodology to engage students to work together with stakeholders in identifying challenges facing electrical power system in Tanzania. This paper presents the experience of using CBL methodology to achieve active learning to engineering students. The dynamicity of the teaching model, allowed students to acquire skills necessary to solve medium to high tech complex problems. The results build a continuous learning platform for students researching in electrical field.Item Active Learning through Smart Grid Model Site in Challenge Based Learning Course(2018-07) Kalinga, Ellen A.; Ibwe, Kwame S.; Mvungi, Nerey H.; Tenhunen, HannuSmart Grid is a new and growing technology to developing countries. Its implementation and sustainability rely on well trained experts. Sustainability of the smart grid need local experts, hence a project named iGRID: Smart Grid Capacity Development and Enhancement in Tanzania was started. The project is running at the College of Information and Communication Technologies, University of Dar es Salaam. It intends to generate the necessary technical and scientific skills to ensure sustainable implementation of smart grid. iGRID project introduced taught PhD and Masters programs focusing on society, innovation and entrepreneurship in iGRID aspects, as well as to facilitate implementation of automation of monitoring, evaluation, analysis, control and management of electrical power system (smart grid) in order to improve delivery efficiency and to optimize operational costs in the electrical power system in Tanzania. The project made use of Challenge-Based Learning (CBL) methodology to engage students to work together with stakeholders in identifying challenges facing electrical power system in Tanzania. This paper presents the experience of using CBL methodology to achieve active learning to engineering students. The dynamicity of the teaching model, allowed students to acquire skills necessary to solve medium to high tech complex problems. The results build a continuous learning platform for students researching in electrical field. Keywords: Active Learning, Smart Grid, Challenge-Based Learning, Tanzania.Item Adopting Renewable Energy in Tanzania: Opportunities and Challenges(IFIP-WG8.9 Enterprise Information Systems, 2017-10-19) Shililiandumi, Naiman; Rwegasira, Diana; Kalinga, Ellen; Kondoro, Aron; Dhaou, Imed Ben; Kwame, Ibwe; Kelati, Amleset; Mvungi, Nerey H.; Tenhunen, HannuAbstract: Solar energy is one of the sources of power that is obtained in a natural way. Many countries, especially developing countries are making use of the renewable energy for the benefit of their communities, however, the issue of counting the benefit of using solar energy, mainly on cost bases remained undefined to many users/consumers at their premises. In this paper, the research on how thermal solar power can effectively be used in the house to minimize the cost, its requirements and the payback money upon investing on solar power is being addressed. The scenario was based on comparing the cost spends by the residential house with thermal solar power and another house without thermal solar power. The analysis shows that the electric energy saving per year when using solar power is about 51.52% for houses and flats, with payback for the investment cost within 3-4 years. The paper also discussed the building blocks for low-cost ICT infrastructures to deploy solar technologies.Item Analysis of Powerline Channel Model for Communication from Primary Substation Node to End-Users(Winter-Spring, 2004) Anatory, Justinian; Mvungi, Nerey H.; Kissaka, Mussa;Abstract—The low voltage power networks in developing countries like Tanzania are designed without taking into consideration their application in data communication. In order to use them for data communication, powerline channel models have been developed and analysed in order to understand the factors that will affect the transmission. In this paper transfer characteristics of powerline channel from power users to primary substation have been modeled and analyzed. Simulation results show that the signal in PLC environment attenuates more with interconnections, which needs to be amplified/regenerated within a few meters.Item Analysis of the Architecture and MAC Protocol for Power-line Networks(2003) Iddi, Hashim U.; Kissaka, Mussa; Mvungi, Nerey H.Item The Analysis Results of Lightning Overvoltages By Atp-Emtp for Lightning Protection Design of A Telephone Line(IEEE, 2007-11) Damas, Jacqueline; Mvungi, Nerey H.Metal Oxide Surge Arrester (MOSA) have been used for telecommunication and power lines transient protection. MOSA has dynamic characteristics that are significant for overvoltages coordination studies regarding fast front surges. Several models with acceptable accuracy have been proposed to study the frequency-dependent behaviour of MOSA. These models differ in calculation and adjustment of the model parameters, some models needs iterative procedure and other models the necessary data are not reported in the manufacturers’ data sheets. A simplified model by Pinceti has been used to study protection of overhead transmission line against direct lightning strike. In this paper, simulations have been performed using the Alternative Transients Program version of Electromagnetic Transient Program (ATP-EMTP) and the results were compared with the ones of manufacturer’s data sheet and found to be satisfactory. Pinceti model has a small relative error of 2.26% for fast transient surge (1/2μs) and of 1.05% for slow transient lightning surge (8/20μs) respectively when compared our results with the results from manufacturers’ data sheet. The simulations were performed for a 3kV TRANQUELL MOSA and its effective protection when applied to the end of 1km line and lightning strike of 0.11/20μs a typical subsequent return stroke current was injected at the middle of the line. It has been observed that, the significant dynamic characteristics of MOSA are that the peak of the voltage wave occurs before the peak of the current wave and that the residual voltage across the MOSA increases as the time to crest of the MOSA discharge current decreases.Item Appropriate Technology for Electrical Power Metering in Tanzania(2004) Anatory, Justinian; Kissaka, Mussa; Mvungi, Nerey H.Item Assessment of Non Transmittable Codewords Enhancement to Viterbi Algorithm Decoding(International Journal of Computer Science and Information Security, 2014) Mrutu, Salehe; Sam, Anael; Mvungi, Nerey H.Researchers have shown that practical mobile communication channels introduce errors that are concentrated in a certain locality rather than random errors. These are burst errors caused by deep fading of the wireless channel or a lightning strike. The existing Viterbi Algorithm (VA) capable of correcting random errors is inefficient in correcting burst errors and therefore resulting in unacceptable amount of residual errors. This paper presents an assessment of Non- Transmittable Codewords (NTCs) enhancement technique to VA in decoding the received signals subjected to burst errors that may occur in poor channels. A hard decision, 1/2 rate and constraint length K is equal to 3 Viterbi Algorithm decoding technique, Binary Phase- Shift Keying (BPSK) and Additional White Gaussian Noise (AWGN) are components used in MATLAB software based simulation when assessing the proposed technique. Applying 6NTCs to VA decoder enables the decoder to reduce 83.7 percent of its residual errors. However, the technique reduces the encoder’s data transmission rate from 1/2 to 1/6.Item Broadband Access Technologies for Rural Connectivity in Developing Countries(IJRRCS, 2011) Simba, F.; Mwinyiwiwa, B.M.; Mjema, E.M.; Trojer, L.; Mvungi, Nerey H.Rural areas especially those of the developing countries provide challenging environment to implement communication infrastructure for data and Internet based services. The main challenges are the high cost of network implementation and lack of customer base, as rural areas are characterized by low income, highly scattered and low population density. This situation drives network operators to establish network infrastructures in urban/city centers leaving rural areas as underserved community. This paper surveys the available connectivity technologies with potentials to offer broadband access network to rural areas. The scope of this survey is on wireless access technologies, due to the fact that they are efficient in terms of cost, time of deployment and network management for rural environment. We provide comparison of the surveyed technologies in terms of their capacity (data rates) and coverage. We also discuss the current deployment of WiMAX and 3G technologies in Africa, which is a home to most of the developing countries. The survey results indicate potential broadband access technologies for rural areas of the developing countries.Item Broadband Power Line Communications: Analysis of Indoor Power Line Network in Developing Countries(JKUAT, 2006) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.The effects of load impedance, line length and branches on the performance of an indoor voltage broadband power line communications (BPLC) are presented in this paper. The power line network topology adopted here is similar to that of the system found in Tanzania. Investigation on effects of network load impedances, direct transmitter to receiver line length, branched line length and numbers of branches have been carried out. The frequency response of the power line transfer function shows that position of notches and peaks in the magnitude and phase responses are largely affected by the above network parameters particularly attenuation and dispersion. The response was also observed in the time domain. The observations made in this work could be useful in the design of high performance PLC systems for data transferItem Broadband Power Line Communications: Analysis of Indoor Power Line Network in Developing Countries(JKUAT, 2006) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.The effects of load impedance, line length and branches on the performance of an indoor voltage broadband power line communications (BPLC) are presented in this paper. The power line network topology adopted here is similar to that of the system found in Tanzania. Investigation on effects of network load impedances, direct transmitter to receiver line length, branched line length and numbers of branches have been carried out. The frequency response of the power line transfer function shows that position of notches and peaks in the magnitude and phase responses are largely affected by the above network parameters particularly attenuation and dispersion. The response was also observed in the time domain. The observations made in this work could be useful in the design of high performance PLC systems for data transferItem Broadband Power line Communications: Performance Analysis: transactions on Engineering, Computing and Technology(2006-12) Anatory, Justinian; Kissaka, Mussa; Theethayi, Nelson; Mvungi, Nerey H.Item Broadband Power Line Communications: The factors Influencing Wave Propagations in the Medium Voltage Lines(IEEE, 2007-03) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.This paper presents the influencing of load impedance, line length and branches on the performance of medium voltage power line communication (PLC) network. The power line network topology adopted here is similar to that of the system in Tanzania. Different investigation with regard to network load impedances, direct line length (from transmitter to receiver), branched line length and number of branches has been investigated. From the frequency response of the transfer function (ratio of the received and transmitted signal), it is seen that position of notches and peaks in the magnitude responses are largely affected in terms of attenuation and dispersion by the above said network parameters/configuration. The observations presented in the paper could be helpful in suitable design of the PLC systems for a better data transfer and system performance.Item Broadband Power Line Communications: The factors Influencing Wave Propagations in the Medium Voltage Lines(IEEE, 2007) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.this paper presents the influencing of load impedance, line length and branches on the performance of medium voltage power line communication (PLC) network. The power line network topology adopted here is similar to that of the system in Tanzania. Different investigation with regard to network load impedances, direct line length (from transmitter to receiver), branched line length and number of branches has been investigated. From the frequency response of the transfer function (ratio of the received and transmitted signal), it is seen that position of notches and peaks in the magnitude responses are largely affected in terms of attenuation and dispersion by the above said network parameters/configuration. The observations presented in the paper could be helpful in suitable design of the PLC systems for a better data transfer and system performance.Item Broadband Power-Line Communication Channel Model: Comparison between Theory and Experiments(IEEE, 2008) Anatory, Justinian; Theethayi, Nelson; Thottappillil, Rajeev; Kissaka, Mussa; Mvungi, Nerey H.Recently different models have been proposed for analyzing the BPLC systems based on transmission line (TL) theory. In this paper one such BPLC model is validated using laboratory experiments by comparing the channel transfer functions. A good agreement between the BPLC model based on TL theory and experiments is found for channel frequencies up to about 100MHzItem A Broadband Power-Line Communication System Design Scheme for Typical Tanzanian Low-Voltage Network(IEEE, 2009) Anatory, Justinian; Theethayi, Nelson; Thottappillil, Rajeev; Mvungi, Nerey H.This paper presents the influence of line length, number of branches (distributed and concentrated), and terminal impedances on the performance of a low-voltage broadband power-line communication channel. For analyses, the systems chosen are typical low-voltage power-line networks found in Tanzania. The parameters varied were the network’s load impedances, direct line length (from transmitter to receiver), branched line lengths, and number of branches. From the frequency responses of the transfer functions (ratio of the received and transmitted signal), it is seen that the position of notches and peaks in the amplitude responses are affected by the aforementioned network parameters and topology. As a result, the time-domain responses are attenuated and distorted. Time-domain responses of power-line channels under various conditions are also investigated for a given pulse input at the transmitter. The observations presented in this paper could be useful for suitable power-line communication system design.Item Broadband Power-Line Communications: The Channel Capacity Analysis(IEEE, 2008-01) Anatory, Justinian; Kissaka, Mussa; Theethayi, Nelson; Thottappillil, Rajeev; Mvungi, Nerey H.The power line has been proposed as a solution to deliver broadband services to end users. Various studies in the recent past have reported a decrease in channel capacity with an increase in the number of branches for a given channel type whether it is an indoor or low-voltage (LV) or medium-voltage (MV) channel. Those studies, however, did not provide a clear insight as to how the channel capacity is related to the number of distributed branches along the line. This paper attempts to quantify and characterize the effects of channel capacity in relation to the number of branches and with different terminal loads for a given type of channel. It is shown that for a power spectral density (PSD) between 90 dBm/Hz to 30 dBm/Hz, the channel capacity decreases by a 20-30 Mb/s/branch, 14-24 Mb/s/branch, and a 20-25 Mb/s/branch for an MV channel, LV channel, and indoor channel, respectively. It is also shown that the channel capacity is minimum when the load impedance is terminated in characteristic impedances for any type of channel treated here. It is shown that there could be a significant loss in channel capacity if a ground return was used instead of a conventional adjacent conductor return. The analysis presented in this paper would help in designing appropriate power-line communication equipment for better and efficient data transfer.Item Broadband PowerLine Communications: Performance Analysis(World Academy of Science, Engineering and Technology, 2008) Anatory, Justinian; Theethayi, Nelson; Kissaka, Mussa; Mvungi, Nerey H.Power line channel is proposed as an alternative for broadband data transmission especially in developing countries like Tanzania [1]. However the channel is affected by stochastic attenuation and deep notches which can lead to the limitation of channel capacity and achievable data rate. Various studies have characterized the channel without giving exactly the maximum performance and limitation in data transfer rate may be this is due to complexity of channel modeling being used. In this paper the channel performance of medium voltage, low voltage and indoor power line channel is presented. In the investigations orthogonal frequency division multiplexing (OFDM) with phase shift keying (PSK) as carrier modulation schemes is considered, for indoor, medium and low voltage channels with typical ten branches and also Golay coding is applied for medium voltage channel. From channels, frequency response deep notches are observed in various frequencies which can lead to reduce the achievable data rate. However, is observed that data rate up to 240Mbps is realized for a signal to noise ratio of about 50dB for indoor and low voltage channels, however for medium voltage a typical link with ten branches is affected by strong multipath and coding is required for feasible broadband data transferItem Broadband Services Provision in Powerline Communications of Developing Countries(IEEE, 2005) Anatory, Justinian; Mvungi, Nerey H.; Kissaka, MussaRecently it has been identified that powerline network is the promise cost effective for broadband accessibility compared to competitors technology. Since, powerline channel has been designed to provide electricity, using it for broadband communication various issues have to be addressed. These include channel characterization, noise, modulation to be used, coding etc. The topology of powerline network affects the transfer characteristics of the channel. In this paper the powerline channel problems have been modeled for utilization by broadband access. In addition different techniques such as application of modulation, and coding have been addressed and the simulation results have been discussed.Item Broadcasting to Handheld Devices: The Challenges(World Academy of Science, Engineering and Technology, 2008) Mvungi, Nerey H.Digital Video Terrestrial Broadcasting (DVB-T) allows combining broadcasting, telephone and data services in one network. It has facilitated mobile TV broadcasting. Mobile TV broadcasting is dominated by fragmentation of standards in use in different continents. In Asia T-DMB and ISDB-T are used while Europe uses mainly DVB-H and in USA it is MediaFLO. Issues of royalty for developers of these different incompatible technologies, investments made and differing local conditions shall make it difficult to agree on a unified standard in a very near future. Despite this shortcoming, mobile TV has shown very good market potential. There are a number of challenges that still exist for regulators, investors and technology developers but the future looks bright. There is need for mobile telephone operators to cooperate with content providers and those operating terrestrial digital broadcasting infrastructure for mutual benefit.