Browsing by Author "Mwambela, Alfred"

Now showing 1 - 12 of 12
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    Collaborative Development and Utilization of iLabs in East Africa
    (2011) Mwikirize, Cosmas; Tumusiime, Arthur A.; Musasizi, Paul I.; Tickodri-Togboa, Sandy S.; Jiwaji, Adnaan; Nombo, Josiah; Maiseli, Baraka; Sapula, Teyana; Mwambela, Alfred
    Since 2005, Makerere University and the University of Dar es Salaaam have taken definitive steps to-ward the development and utilization of iLabs. This chapter presents the iLabs experiences of the two East African universities. The experiences presented here are characterized by: institutionalization of developer teams, development of ELVIS-based iLabs, staff & student exchanges, and utilization of iLabs to support curricula. The two universities have also undertaken to setup iLabs communities at peer universities and other higher institutions of learning in East Africa.
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    Collaborative Development and Utilization of iLabs in East Africa
    (IGI Global, 2012) Mwikirize, Cosmas; Tumusiime, Arthur Asiimwe; Musasizi, Paul Isaac; Tickodri-Togboa, Sandy Stevens; Jiwaji, Adnaan; Nombo, Josiah; Maiseli, Baraka J.; Sapula, Teyana; Mwambela, Alfred
    Since 2005, Makerere University and the University of Dar es Salaaam have taken definitive steps to-ward the development and utilization of iLabs. This chapter presents the iLabs experiences of the two East African universities. The experiences presented here are characterized by: institutionalization of developer teams, development of ELVIS-based iLabs, staff & student exchanges, and utilization of iLabs to support curricula. The two universities have also undertaken to setup iLabs communities at peer universities and other higher institutions of learning in East Africa.
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    Collaborative Development of Remote Electronics Laboratories in the ELVIS Ilab
    (American Society for Engineering Education, 2009) Jiwaji, Adnaan; Hardison, Jazmine; Ayodele, Kayode P.; Stevens, Sandy; Mwambela, Alfred; Mwambela, Alfred; Harward, Judson; del Alamo, J. A.; Harrison, B.; Gikandi, S.
    Remote laboratories represent a significant value to engineering curricula in a variety of cases. Whether it is a complement to a hands-on experience or a substitute when a traditional lab is not feasible, remote laboratories can be a valuable educational resource. Since 1998, the MIT iLab Project has worked to increase the quality and availability of remote laboratories. Using the iLab Shared Architecture, developers of new labs can leverage a set of generic support functions and then share those labs easily and with minimal administrative cost. More recently, the iLab Project, in partnership with Obafemi Awolowo University in Nigeria, Makerere University in Uganda and the University of Dar-es-Salaam in Tanzania and in coordination with the Maricopa Advanced Technology Education Center (MATEC), has focused on building iLabs around the National Instruments Educational Laboratory Virtual Instrumentation Suite (ELVIS) platform. The ELVIS is a low-cost, small-footprint unit that contains most of the common test instruments found in a typical electrical engineering lab. By coupling the ELVIS with iLabs, a variety of remote electronics laboratories can be built and shared around the world. Using this common hardware/software platform, participants in the iLab Project at different levels of the educational spectrum have developed experiments that meet their individual curricular needs and are able to host them for use by other peer institutions. Not only does this increase the variety of ELVISbased iLabs, but it also spurs the creation of teams that can then build other, more diverse iLabs and substantively participate in project-wide collaborative development efforts. Through such coordinated efforts, iLabs can provide rich practical experiences for students in areas not previously possible at institutions across the educational spectrum.
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    Development of Online Optical Fiber Communications Experiments using the Interactive ILabs Shared Architecture
    (2015) Misso, Angelina; Mwambela, Alfred
    An intervention approach in introducing new online fiber optic communications labs in an operating environment where resources for establishing new conventional labs are limited is presented. The focus of this educational intervention is on the technological aspect required to develop and deploy the labs online. The developed labs demonstrated some of the distinctive features of fiber optic communications compared to the conventional electronics copper wire communications media. Telecommunications kits from Emona – FOTEx, National Instruments – ELVIS II hardware platform and MIT iLabs Shared Architecture remote lab framework were used to develop and deploy online fiber optic experiments. The developed labs have provided means for students to perform relatively new lab work anytime, anywhere. The sharing aspects extend their accessibility to other institutions with similar operating environment and limited technical knowhow on managing remote labs.
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    Entropic Thresholding Methods in Reconstruction of Capacitance Tomography Data
    (IEEE, 1996) Mwambela, Alfred; Isaksen, O.; Johansen, Geir A.
    High quality reconstruction of capacitance tomography data is of vital importance for the extraction of quantitative information from such systems. The use of such soft-field sensor systems and the LBP reconstruction algorithm produces distortions in the reconstructed tomogram data (i.e. the true intensity values and their location in the tomogram under consideration are corrupted or altered). The main problem with LBP reconstruction algorithm is a smearing effect of sharp transitions in the dielectric constants. Several authors have suggested different approaches for improving the quality of the reconstructed tomogram. The quality of the generated tomograms could be improved by including a thresholding procedure in the reconstruction process for the purpose of minimising these distortions. Here, the use of global entropic thresholding methods in the reconstruction process of capacitance tomography data is reported. The results obtained are compared to the previously published thresholding methods of Xie et al. (1992) and an Implicit Model based reconstruction. It is concluded that distortions in the reconstructed capacitance tomograms can be minimised by using a thresholding procedure. It can be seen that the evaluated global entropic thresholding methods without supervision cannot be used to produce reasonably accurate results when it comes to multicomponent flow imaging. The smearing effect of the LBP reconstruction algorithms blur the phase transition making it hard for autothresholding, particularly for small objects. This effect is more pronounced when the two components under investigation have a small difference in permitivity
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    Feasibility Study of Community Earthquake Warning System Proposed for Mbeya City and Surrounding Regions
    (Scientific Research, 2014) Manyele, Asinta; Mwambela, Alfred
    The Mbeya city and its surrounding regions (Rukwa, Katavi and Njombe) in south western Tanzania, fall among the fast growing economical regions in Tanzania. It is also unfortunately under potential for seismic risk due to its proximity to the western and eastern junction of the East African Rift (EAR) Valley. Construction of Community Earthquake Early Warning (CEEW) system model based on community owned MEMS accelerometer sensors in being proposed for the region. To optimize the warning time function and as the process of planning and designing the community-hosted seismic network, the paper presents the simulation of warning times that can be realized in this region based on the distribution of sensor stations in relation to the historical strong earthquakes and target sites. The distribution of sensor stations determines the detection and reporting time of the event, while location of earthquakes and position of target site determine the available warning time for the target to be protected. Testing the various sensor station configurations (regional, On-site and Hybrid) models of CEEWS by simulation of scenario earthquakes, the hybrid configuration that distributes sensor stations closer to the source and on target sites, was able to provide at least 5 seconds of warning times to various targets. This time has been demonstrated to be enough for shutting down hazardous industrial processes and for people to take cover at safer locations to reduce injuries.
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    A Grey Level Fitting Mechanism based on Gompertz Function for Two Phase Flow Imaging using Electrical Capacitance Tomography Measurement Systems
    (2014) Nombo, Josiah; Mwambela, Alfred; Kisangiri, Michael
    Electrical Capacitance Tomography (ECT) is an image generating system based on soft field sensory system. The preferred Linear Back Projection (LPB) reconstruction algorithm for multi-phase measurement has blurring effect on the image generated. These two inherent factors, among others, affect the quality of image generated from ECT systems. Introducing fitting in the image generation process is one the solutions to improving its quality. In this article an alternative fitting mechanism based on the Gompertz function has been developed and evaluated. Comparative analysis results shows improvement on the spatial quality of images generated, in terms of minimum relative image and distribution errors, maximum correlation coefficient, and at relatively no additional computational cost. The mechanism is more effective for annular than stratified flow data hence complimenting the weakness of Xie method for annular flow.
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    Integration of a Low Cost Switching Mechanism into the NI ELVIS Ilab Shared Architecture Platform
    (IEEE, 2012) Msuya, Hubert; Mwambela, Alfred
    This paper presents the development of a low cost switching mechanism into the NI ELVIS platform for online laboratories based on the iLab Shared Architecture. This came up after experiencing the limitations on using NI ELVIS II+ platform in deploying discrete experiments using common measuring and testing instruments; as well as the use of different components on the same experimental setup. This requires switching mechanisms as a solution to implement those experiments. The designed mechanism in this work uses analogue switching devices with digital control inputs connected to the NI ELVIS II+ Digital writer instrument. The mechanism were successfully tested using implementation of diode rectification characteristics experiments showing the switching mechanism between different components; whereas switching between different experimental setups was shown using Low Pass Filter, High Pass Filter and Band Pass Filter setups.
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    Multiphase Flow Component Volume Fraction Measurement: Experimental Evaluation of Entropic Thresholding Methods Using an Electrical Capacitance Tomography System
    (2001) Mwambela, Alfred; Johansen, Geir A.
    A laboratory experiment to measure component volume fractions in a multiphase flow of an oil/gas/water mixture, where water is the discontinuous phase, has been conducted using a measurement system based on electrical capacitance tomography. The image reconstruction algorithm of the electrical capacitance tomography system has been modified to incorporate entropic thresholding methods, which facilitate accurate information extraction from the tomograms. Evaluation results show that this approach, using only one thresholding method, fails to meet the desired requirements over the full component volume fraction range, is flow regime dependent and is highly dependent on the concentration of the components in the mixture. However, some of the algorithms developed are complementary with the conventional algorithms over the full component volume fraction range. Integration of complementary algorithms improves the overall measurement results to within the desired requirements for operational purposes in the oil industry.
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    Performance Analysis of Grey Level Fitting Mechanism based Gompertz Function for Image Reconstruction Algorithms in Electrical Capacitance Tomography Measurement System
    (2015) Nombo, Josiah; Mwambela, Alfred; Kisangiri, Michael
    This paper analyses the performance of grey level fitting mechanism based on Gompertz function used in Electrical Capacitance Tomography measurement system. In order to evaluate its performance, the data fitting mechanism has been applied to common image reconstruction algorithms which include; Linear Back Projection, Singular Value Decomposition, Tikhonov Regularization, Iterative Tikhonov Regularization, Landweber iteration and Projected Landweber iteration. Images were reconstructed using measured capacitance data for annular and stratified flows, and qualitative and quantitative evaluation were done on the reconstructed images in comparison with respective reference images. Results show that this grey level fitting mechanism is better in terms of improving image spatial resolution, minimizing relative image error and distribution error and maximizing correlation coefficient.
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    The Use of Entropic Thresholding Methods in Reconstruction of Capacitance Tomography Data
    (Elsevier, 1997) Mwambela, Alfred; Isaksen, Ø.; Johansen, Geir A.
    High-quality reconstruction of capacitance tomography data is of vital importance to ensure quantitative information from such systems. Several methods have been tested, such as linear back projection (LBP), representing a fast and crude method, and model-based reconstruction (MOR) which significantly improves the results, although at higher computational cost. The main problem of using LBP is the smoothing effect on sharp transitions in the dielectric constant distribution. The reconstruction quality could be improved by including a thresholding procedure in the reconstruction process. In this work, entropic thresholding methods are used. These methods are compared to previously published thresholding techniques such as Xie's method and an implicit model-based reconstruction method. A computer simulated eight-electrode capacitance tomography system has been used for the evaluation.
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    Web-Accessible Liquid Distillation Column Temperature Monitoring and Control using ilab Shared Architecture
    (2013) Bulugu, Isack; Mwambela, Alfred
    The liquid distillation column is a research facility used in chemical and processing engineering at University of Dar es salaam. Originally it has been manually operated require the presence of operators all-time. It is used to control and take measurements data under hazardous operating condition. In this work the research equipment has been automated and its control and monitoring can now operate online, hence shared by many researchers. In this paper, the major findings were data acquisition device (DAQ) NI USB 6211 for acquiring temperatures and generate signals for control purposes, and thermocouples type K sensors were used since they can operate at very wide temperature range of -270 to 1370. The main parameter which has been monitored is temperature at various parts of the distillation column including temperature of the top/bottom and reboiler temperature. The approach used was computer controlled using Data acquisition device and labVIEW graphical programming language as standalone control system to extent it control and monitoring temperature online. The Interactive ilab shared architecture has been used to make the system accessible remotely. Labserver was created then interfaced with distillation column using NI USB 6211 as a data acquisition device. The DAQ was configured for temperature acquisition and signal generation for monitoring temperature and flux flow control respectively. For the remotely operation, the Labserver was connected to the LAN/internet and the distillation column was accessed through web services.