Browsing by Author "Nkansah-Gyekye, Yaw"

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The Effect of Seasonal Weather Variation on the Dynamics of the Plague Disease
(Hindawi International Journal of Mathematics and Mathematical Sciences, 2017-08-10) Ngeleja, Rigobert; Luboobi, Livingstone; Nkansah-Gyekye, Yaw
Plague is a historic disease which is also known to be the most devastating disease that ever occurred in human history, caused by gram-negative bacteria known as Yersinia pestis.The disease is mostly affected by variations of weather conditions as it disturbs the normal behavior of main plague disease transmission agents, namely, human beings, rodents, fleas, and pathogens, in the environment. This in turn changes the way they interact with each other and ultimately leads to a periodic transmission of plague disease. In this paper, we formulate a periodic epidemic model system by incorporating seasonal transmission rate in order to study the effect of seasonal weather variation on the dynamics of plague disease.We compute the basic reproduction number of a proposed model.We then use numerical simulation to illustrate the effect of different weather dependent parameters on the basic reproduction number. We are able to deduce that infection rate, progression rates from primary forms of plague disease to more severe forms of plague disease, and the infectious flea abundance affect, to a large extent, the number of bubonic, septicemic, and pneumonic plague infective agents. We recommend that it is more reasonable to consider these factors that have been shown to have a significant effect on 𝑅𝑇 for effective control strategies.
Implementation of a goal programming model for solid waste management: a case study of Dar es Salaam – Tanzania
(EDP Sciences, 2017) Lyeme, Halidi Ally; Mushi, Allen; Nkansah-Gyekye, Yaw
Abstract – In this research article, the multi-objective optimization model for solid waste management problem is solved by the goal programming method. The model has three objectives: total cost minimization, minimization of final waste disposal to the landfill, and environmental impact minimization. First, the model is solved for the higher priority goal, and then its value is never allowed to deteriorate. The model is solved for the next priority goal and so on until the problem is solved. The model was tested with real data for solid waste management system from Dar es Salaam city. The results determine the best locations for recycling plants, separating plants, composting plants, incinerating plants, landfill and waste flow allocation between them. Furthermore, the solution shows a high reduction of the amount of waste to the landfill and greenhouse gas emissions by 78% and 57.5% respectively if fully implemented compared to the current system.
The in-Human Host and in-Mosquito Dynamics of Malaria Parasites With Immune Responses
(New Trends in Mathematical Sciences, 2017-08-25) Seleman A., Mohamedi; Luboobi S., Livingstone; Nkansah-Gyekye, Yaw
In this study, a mathematical model for the in-human host and in-mosquito dynamics of malaria parasite with immune responses was formualeted and analyzed. A positive invariant region of the model was established, and a basic reproduction number R0, of the model was computed. Existence and stability of two non-negative equilibrium points: malaria free equilibrium (MFE) and malaria infection equlibrium (MIE) were established. We, also proved that MFE is locally asymptotically stable if R0 < 1 and globally asymptotically stable (GAS) if R0 ≤ 1. Numerical simulations prove that MIE exists and is GAS. Moreover, our results revealed that immunity has significant influence on lowering malaria infection at blood and mosquito stages. However, an insignificant effect of immunity on both cells and parasites at liver stage infection was observed. Furthermore, the model depicts that infection decreases as lifespan of immune cells increases. The impact of immune cells to suppress production of merozoites is noted to be higher than that of antibodies to block invasion of sporozoites and merozoites.
A Matlab based Graphical User Interface for Computing Optimal Diet of People Living with HIV at Asyptomatic Stage
(International Journal of Computer Applications, 2015-07) Kowa, Yasin; Mpolya, Emmanuel; Nkansah-Gyekye, Yaw
Achieving basic nutritional recommendations for people liv-ing with HIV is important at all stages as the virus affects the immune system and renders an infected person to contract other infections easily. Poor nutrition strengthens the effects of HIV as malnutrition adds to deterioration of the immune system. This leads to a poor prognosis of the disease. Thus a tool to determine adequate amount and good combination of different available foods that ensures optimal nutrients will prove useful if designed. In this paper, a MATLAB based Graphical User Interface (GUI) that will be used to compute adequate amount of foods which will lead to the achievements of recommended nutrient intakes for these patients has been developed. The design and use of a GUI can be extended to various telecommunication devices and be accessible to a normal person and other groups in needs of diet management and therefore it will have a wider application.
Modeling Diet Decisions for People Living with HIV in Consideration of Age, Weight, Height, and Gender Constraints
(Scientific & Academic Publishing, 2015) Kowa, Yasin; Nkansah-Gyekye, Yaw; Mpolya, Emmanuel
People living with HIV as well as AIDS patients, who do not receive proper and timely medical treatment, are open targets for all kinds of other infections owing mainly to their relatively weak immune systems. We emphasizes upon the fact that, in most (if not all) such cases, poor nutrition intensifies the progression of the disease and that achieving basic nutritional recommendations is important at all stages of the disease. This paper aims to develop a cost-effectiveness computing model (mathematical model) in diet decisions for people living with HIV in consideration of age, weight, height, and gender constraints. The consideration of these factors tends to avoid undertaking/overtaking of the nutrients which may lead to more serious problems. This model combines multiple linear regression model and linear programming model. The multiple linear regression model predicts the nutrient requirements in the human body of the factors age, weight, height, and gender. The multiple linear regression model gives out the maximum allowable amount of nutrients (upper bound) and minimum amount of nutrients required (lower bound). These results are used to restrict some constraints in the linear programming model, while others are restricted to the maximum allowable amount of foods. From the linear programming model adequate amount of foods that achieve the nutrients recommended are computed. The linear programming problem formulated is solved by the two phase simplex method in MATLAB. Results show that multiple linear regression predicted values are close enough to the actual recommended dietary/daily intake values. The optimal nutrients are reached at much less cost when the multiple linear regression predicted values are used as nutrient recommendations to restrict the constraints in linear programming model compared to when actual recommended dietary/daily intake values are used. Since our model gives adequate amount of foods at much less cost than when the actual values are used then this justifies that our goal has been successful reached. The mathematical model developed could potentially be extended to different groups of people who must manage their diets and therefore promises to have a wider applicability.
Modeling the SBC Tanzania Production-Distribution Logistics Network
(IISTE, 2017-07) Dzupire, Nelson; Nkansah-Gyekye, Yaw; Mirau, Silas
The increase in customer expectation in terms of cost and services rendered, coupled with competitive business environment and uncertainty in cost of raw materials have posed challenges on effective supply chain engineering making it essential to do cost-benefit analysis before making final decisions on production, distribution logistics. This paper provides a conceptual model that provide guidance in supply chain decision making for business expansion. It presents a mathematical model for production-distribution of an integrated supply chain derived from current operations of SBC Tanzania Ltd which is a major supply chain that manages products' distribution in whole of Tanzania. In addition to finding the optimal cost, we also carried out a sensitivity analysis on the model so as to find ways in which the company can expand at optimal cost, while meeting customers' demands. Genetic algorithms is used to run the simulation for their efficient in solving combinatorial problems.
Sensitivity analysis of multi-objective optimization for solid waste management: A case study of Dares Salaam, Tanzania
(BISKA Bilisim Technology, 2017-11-08) Lyeme, Halidi A.; Mushi, Allen; Nkansah-Gyekye, Yaw
In this study, a sensitivity analysis of a multi-objective optimization model for solid waste management (SWM) for Dar es Salaam city in Tanzania is considered. Our objectives were to identify the most sensitive parameters and effect of other input data to the model output. Five scenarios were considered by varying their associated parameter values. The results showed that the decrease of total cost for the SWMsystem in all scenarios was observed compared to the baseline solution when the single landfill was considered. Furthermore, the analysis shows that the variable cost parameter for the processing facilities is very sensitivity in such a way that if you increase the variable cost then, there is a rapid increase of total cost for the SWM system and the vice versa is true. The relevant suggestions to the decision makers were also discussed.
Towards A Secure Remote Electronic Voting in Tanzania Organizational Challenges
(Advances in Computer Science: an International Journal, 2014-09) Kimbi, Sylvester; Nkansah-Gyekye, Yaw; Michael, Kisangiri
This paper discusses organizational challenges that hinder the implementation of secure remote electronic voting in Tanzania and proposes workable solutions to address the identified challenges. The work presented in this paper complements a proposed secure model that would facilitate the implementation of secure, trustworthy and sustainable electronic voting via Internet and mobile phones in Tanzania. The proposed model together with technical recommendations is presented in a separate research paper titled "A Secure Model for Remote Electronic Voting: A Case of Tanzania". Data was collected using selfadministered questionnaires and interviews. The data was collected from (1) experts in the area of information security and information technology, (2) lawyers, and (3) election officials. We also reviewed the election act and constitution of the United Republic of Tanzania. We conclude that technical solutions alone can not provide a level of assurance that is required for trustworthy, secure and sustainable remote electronic voting system. Nontechnical solutions should be consideredas well. Thus a holistic approach should be adopted to pave the road to a successful implementation of remote electronic voting in legally binding political elections in the country.