Department of Computer Science and Engineering

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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
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.
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.
Application and Network Level Arbitration for Development of Quality of Experience Metric
(2003) Mbise, Mercy
This paper examines an arbitration mechanism where redundant video packets are selectively removed, resulting in an improvement in the video quality whilst freeing up resources for other interactive traffic. The interaction between multimedia streams is investigated, where video and a still image are apparent simultaneously, and the effects of transmitting these media over the same channel examined. Network and application level arbitration policies are examined for a simulated and real network. The relationship between the objective quality of service metrics available from the network & application, and the subjective perception of quality of experience are considered, and used to develop the end-user's quality of experience metric. The findings are consolidated and used to derive policies for network and application level arbitration, to provide maximum quality of experience to the end-user.
Security Mechanisms For Electronic Patient Records In Mobile Intelligent Services
(MEDINF, 2003) Kapis, Kosmas; Van Der Lubbe, Jan C.
The deficiencies found in conventional paper-based patient records, practiced in healthcare service provision, have resulted in the emerging development of electronic patient record (EPR) systems. This paper proposes a cryptographybased EPR security model guaranteeing the patient’s record integrity, accountability, confidentiality and patient record access consent. For this model several possible cryptographic security mechanisms are studied. The advantages and disadvantages of each scheme are considered, and based on the EPR requirements the mechanism with best results is suggested.
Evaluation of Latency Effects of a Long-Term Burst on Video For Selective Removal of Dependant Packets
(2003) Mbise, Mercy; Woods, John C.
This paper presents the evaluation of multimedia traffic interaction in terms of induced latency. Experiments are conducted in a distance-leaming platform where long-term burst effects are examined together with video in the same channel. The effects of policy on a user's QoE are examined. If a packet exceeds ITU-T recs. G. 114, it is of no use to a timely play-out device, and should be selectively discarded from forwarding mechanisms. This permits the removal of packets by arbitration mechanisms according to what has happened previously to the stream. The interdependent nature of video packets permits the predictive dependants of intra-coded parents to themselves be discarded, resulting in a temporal compromise rather than an accumulation of errors.
Arbitration by Selective Removal of Temporally Dependent Redundancies
(Visual Information Engineering, 2003. VIE 2003. International Conference on, 2003) Mbise, Mercy; Woods, John C.
This paper examines the transmission of real-time video and still images over the same medium, and presents an arbitration mechanism for efficient transfer of bulky data in the presence of scarce resources, by intelligently compromising the video stream. The arbitration selectively removes video packets based on the observation that if an intra-coded packet is lost, its dependants will not enhance the video but actually degrade it. The identification of this event permits them to be discarded thus freeing up resources at the expense of reduced temporal rate. This principle is also true for packets exceeding the end-to-end delay requirement and it can also be applied towards the end of scenes where information content is low. The freeing of resources improves the mean buffer occupancy; therefore losses and delay are reduced. A series of simulations are conducted to illustrate these points
Data Flows in Health Information Systems: An Action Research Study of Reporting Routine Health Delivery Services and Implementation of Computer Databases in Health Information Systems
(2003-05-02) Lungo, Juma H.
This study evaluated the reporting of routine health delivery services and prototyped a computer database, district health information software (DHIS), in the health information systems in Tanzania and Mozambique using case study sites in Bagamoyo district and Gaza province in Tanzania and Mozambique, respectively, from March to August 2002. The purpose of the study was to assess and determine the quality and quantity of reporting of health delivery services; and the benefit, challenges, and conditions for implementing a computer database at the district level of the health information systems in both countries. The study falls under the framework of action research, where the phases of action research (diagnosis, action planning, action taking, evaluation, and specifying learning) were executed in sequence and cyclically. The diagnosis phase of the study was carried out through interviews, questionnaire, analysis of texts and documents, and participant observations. Appropriate actions were planned. In the action phase, software was developed in order to migrate data from existing computer databases to the DHIS; data were migrated from paper-based databases to the DHIS; and the DHIS was translated into Swahili while adopted in Tanzania. Evaluation of the actions taken was conducted through group discussions and workshops with health workers. To specify learning, reports of the results were prepared and presented to the Ministries of Health for review. The results were analysed using the DHIS, SPSS computer software, and using content analysis. The findings were presented quantitatively and qualitatively using tables, graphs, figures, photos, and elaboration. The findings indicated that the health data being reported were not sufficient to support informed decision-making and health planning. The causes of the low quality of the data identified include incomplete, inaccurate, and untimely reporting; lack of resources and office space; existence of legacy information systems; and the existence of parallel reporting systems in the health information systems. The findings also indicated the major challenges in introducing computer databases to be the participation of users and the existing computer database systems. The study demonstrated that the DHIS is suitable software for the health information systems, and that data locked in legacy information systems can be safely extracted and migrated to new information systems.
Energy Meter Reading and Tampering protection through Powerline Communication Channel
(FoE, 2004) Naiman, S.; Kissaka, Mussa; Mvungi, Nerey H.
Power utility companies have suffered revenue losses due to uncollected bills and energy tampering for many years. The use of powerline communication to overcome the problems has been proposed. This needs tampering detection and transceivers capable of communicating data through powerline channel. This paper identifies different methods of tampering, presents simulated results for tampering detection scheme and proposes a Direct Sequence Spread Spectrum (DSSS) with Binary Phase Shift Keying (BPSK) transceiver design for energy metering as a solution to the problem. The choice of DSSS-BPSK modulation scheme is based on its robustness and its ability to spread signal into wide band to protect jamming and interference. The performance of the designed tampering detection, transceiver and selection of suitable parameters is performed by using matlab software
The Impacts of Legacy Information Systems in Reporting Routine Health Delivery Services: Case Studies from Mozambique and Tanzania
(2004) Lungo, Juma H.; Nhampossa, José L
The awareness of the importance of effective health information systems (HIS) has increased substantially and is reflected by many ongoing efforts of HISs reform in many developing countries. However, the one mostly mentioned obstacle for health information systems reform is Legacy Information Systems (LIS). The impacts of LIS in the reporting of routine health delivery services were studied in a participatory action research using case study sites in Tanzania and Mozambique. LIS impacts are on the process of introducing changes (reforms) on the HIS, and on everyday functioning of the HIS. LIS were determined to cause poor quality of health data, incomplete reporting of health data, and burden to health workers. The study recommends the Ministries of Health to relinquish the LIS. A demonstration on extracting and loading of locked health data on LIS to new health information software using extraction transformation and loading (ETL) software was performed.
Determination of Maximum Data Transmission Distance in Powerline Networks in Developing Countries
(EAJST, 2004) Anatory, Justinian; Mvungi, Nerey H.; Kissaka, Mussa
Recently, Powerline communications has been considered for providing broadband access services and as a cost effective means of connectivity to non-urban and lowly populated areas. This indicates that it is a viable technology for developing countries like Tanzania where there is adequate penetration of the powerline networks. However, the use of the network for data transmission presents a number of problems that limits achievable transmission distances (hops). This paper looks at different modulation and coding techniques to maximize transmission distance
Best packetization scheme for H.263 internet video communication
(IET, 2004) Paredes-Farrera, M.; Fleury, Martin; Mbise, Mercy; Ghanbari, Mohammed
The H.263 codec is an efficient way to stream variable bit-rate video sequences. It is proposed that, for equivalent bandwidth and frame rate, a two-slice packetisation scheme results in superior peak signal-to-noise ratio, rather than the conventional one-slice scheme, and that constant inter-packet gap rather than 'bursty' delivery is preferable.
Cryptographic Approach to Patient Records Privacy Protection in Emergency Situations
(2004-06) Kapis, Kosmas; Van Der Lubbe, Jan C.; Cartrysse, Kathy
This paper presents cryptographic mechanisms for securing electronic medical patient records, EPRs in emergency situations. The mechanism maintains the EPR confidentiality during an emergency when a patient is unconscious and located outside any health provider, HP. In such situations any authorized health care practitioner, HCP can access all relevant medical records when needed. However, after such an emergency, it is impossible for anyone to access the patient’s EPR without the patient’s consent. This can be achieved by using a modified forward-secure signature and encryption algorithm used in two directions. After an emergency treatment, the patient’s consent is restored.
Broadband Services Provision in Powerline Communications of Developing Countries
(IEEE, 2005) Anatory, Justinian; Mvungi, Nerey H.; Kissaka, Mussa
Recently 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.
Strategies for Development and Integration of Health Information Systems: Coping With Historicity and Heterogeneity
(2005) Aanestad, Margunn; Monteir, Eric; Kimaro, Honest C.; Macombe, Esselina; Macueve, Gertrudes; Mukama, Faraja; Muquingue, Humberto; Nhampossa, Jose Leopoldo; Lungo, Juma
Health is crucial for development, and well-working health information systems are required for sound decision making and effective use of resources. However, establishing working information systems in developing countries is truly a challenge. Moreover, strategies for the development and integration of large and growing collections of information systems escape simplistic recipes. This is a pressing practical problem globally, as well as analytically under-researched within the IS field. We aim to contribute to the understanding and development of such strategies by underscoring two core dilemmas: (i) the conservative influence of historically accumulated and institutionalized practices, technologies and perceptions (dubbed the ‘historicity’ of information systems) and (ii) the lacking integration and increasing fragmentation across the collection of information systems (dubbed the ‘heterogeneity’ of information systems). The empirical underpinning for our analysis is an action research project, the Health Information Systems Program (HISP), which aims at improving existing suboptimal health information systems in developing countries. HISP provides a particularly poignant illustration of the challenges related to historicity and heterogeneity of information systems as these are implied in the politico-historical context. Our empirical material is a cross-national comparative analysis of the current reporting systems for administrative health data in Mozambique, Tanzania and in the state of Andhra Pradesh in India. Several problems are associated with the existing systems and the need to change or replace them is recognized. For example, due to the donor- and aid-dependent economies of most developing countries, there are often other specialized health care programs e.g. targeted towards specific diseases like malaria, tuberculosis and HIV/AIDS. These programs usually have their own reporting systems, and the result emerging over time is a disintegrated and heterogeneous collection of systems. The challenges associated with attempting to change such large-scale, heterogeneous and fragmented systems involve complex dilemmas. As the current information systems are embedded and institutionalized nationwide, a realistic strategy need to take a phased approach whereby present systems are gradually integrated into the environment. In the case of donor-supported and -managed program, the national health authorities may not even have the required power to intervene. Thus the existing reality cannot be ignored or done away with, whether it be the information systems, the institutions or the work practices; they constitute the point of departure. Analytically, we draw on recent socio-technical conceptualizations of large, integrated systems - so-called information infrastructures - especially through recent elaborations in the theoretical foundation in actor-network theory (ANT). The development strategy we suggest emphasizes an evolutionary, ‘cultivating’ approach while at the same time accepting that there will be a certain level of non-integration (often perceived of as ‘mess’) as chronic.
Analyzing the Problem of Unsustainable Health Information Systems in Less-Developed Economies: Case Studies from Tanzania and Mozambique
(Wiley Online Library, 2005-01-29) Kimaro, Honest C.; Nhampossa, José L.
Most of donor-supported information technology (IT)–based projects developed or implemented in less-developed economies (LDEs) end up as complete or partial failures or unsustainable. Notably, a number of intra-organizational and external factors are associated with this problem, including inadequate infrastructure and human resource capacity, fragmented donor policy, and lack of policies to manage the sustainability problem. Accordingly, IT initiatives are often donor-driven, top-down, and hijacked by top managers who (normally) do not have adequate skills, but have enormous power to enforce such initiatives across organizational hierarchies. In analyzing the concepts from sustainability and institutionalization, key insights towards a better understanding of the problem of unsustainability are developed. It is argued that health information systems (HISs) become sustainable if they are institutionalized in the sense of being integrated into the everyday routine of the user organization. However, a sustainable HIS should also be flexible enough to allow changes as the user needs change. Moreover, introduction of a new HIS is not only a technical change, but requires the cultivation and institutionalization of a new kind of culture. Through a comparative case analysis of the HIS development and implementation processes in Tanzania and Mozambique, we have identified two sets of relationships, between the Ministry of Health (MoH) and donor agencies and between the MoH and software development agencies as critical and contributing factors to the unsustainability of a HIS. Given this setting, we highlight three key strategies for dealing with the problem of unsustainability in LDEs: (a) integration of a HIS, (b) local shaping of new cultures, and (c) cultivation approach to systems development.
Analysing the Hindrance to the Use of Information and Technology for Improving Efficiency of Health Care Delivery System in Tanzania
(2005-09) Kimaro, Honest C.; Twaakyondo, Hashim M.
Information Technologies (IT) have been described as offering tremendous opportunity to improve health services as well as in meeting broader developmental goals which have an impact on health. Through the use of IT, healthcare sectors can potentially plan, monitor and evaluate health services as well as communicate more effectively within and across organizational hierarchies. However, a number of studies suggest several hindrances where the use of IT to bring critical change in the health sector of Tanzania has been problematic. Despite the lack of appropriate use of the existing IT resources in the health sector, donors and government have continued helping the health sector to acquire up-to-date IT resources while however placing little emphasis on long term IT training, data management and effective utilization of information resulting into wasted of such resources hence little improvement in health services delivery. This study is based on the Health Information System Programme (HISP), an action research project aimed at improving health information system in developing countries with the use of IT and information for local action. Under the project, the district health information software which is customizable, open source and freely distributed has been implemented in five pilot districts in Tanzania. The lessons learned from HISP project and other levels of the health sector in general indicate the lack of skills for data interpretation and utilisation, policy guidelines on information and human capacity building as well as a lack of flexible system.
MAINS VOLTAGE PROFILE IN DAR ES SALAAM: A CASE STUDY
(JKUAT, 2006) Mvungi, Nerey H.
Electrical and electronic systems and equipment need the mains supply voltage to be at normal level and to remain stable to ensure proper operation and long service time for such equipment. However, the stability of the mains supply and level has been observed to be a problem in Tanzania for sometime now particularly in residential areas. This paper present the results of a study made over a period of six mouths in various parts of Dar es Salaam. The result confirms that power quality in a number of places is unacceptable particularly between 6-9p.m when the voltage drop is as low as 40% and as high 17.4% above the normal value. The paper further proposes the method to address the problems at the consumer end.
Critical issues associated with adoption and use of open source software in public sector: Insights from Tanzania
(2006) Lungo, Juma H.
Two Open Source Software (OSS) projects in Tanzania are discussed as exemplar efforts for the adaptation and use of OSS in public sector. The projects investigated in this Action Research Study were from the Health and Education Sectors. The two projects are of important in that, they use two different approaches of embracing OSS where the Health Sector project uses an approach of getting existing and working open source software framework and customizes it with the help of contributors from Open Source Community, while the Education Sector project developed software from scratch under the auspice of OSS development approach. A comparative analysis of the two projects with the terms of the Open Source Software definition indicates that the two developed software did not take into consideration of all OSS terms. The study concludes that the deviation from the terms of OSS definition reflect incompatibility between free software and open source software philosophies which results into difficulties to comply with one of them. As a result the focus is to achieve the freedom to use the software for any purpose and for any number of computers and the freedom to maintain the software without depending on the author of the software.
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 transfer

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