Yaw Nkansah-Gyekye

Unsteady flow of variable viscosity Cu-water and Al2O3-water nanofluids in a porous pipe with buoyancy force

Purpose – The purpose of this paper is to investigate the combined effects of buoyancy force and variable viscosity on unsteady flow and heat transfer of water-based nanofluid containing copper and alumina as nanoparticles through a porous pipe. Design/methodology/approach – Using the Boussinesq and boundary-layer approximations with Buongiorno nanofluid model. The governing nonlinear partial differential equations for the continuity, momentum and energy balance are formulated. The equations obtained are solved numerically using a semi-discretization finite difference method (know) as method of line coupled with Runge-Kutta-Fehlberg integration scheme. Findings – Numerical results for the skin-friction, heat transfer and for the velocity and temperature profiles are obtained. The results show that with suction, Cu-water produces higher skin friction and heat transfer rate than Al2O3-water. Both nanofluids velocity and temperature increase with a decrease in viscosity and an increase in buoyancy force inte...

Numerical study of unsteady MHD Couette flow and heat transfer of nanofluids in a rotating system with convective cooling

Purpose – The purpose of this paper is to investigate numerically the unsteady MHD Couette flow and heat transfer of viscous, incompressible and electrically conducting nanofluids between two parallel plates in a rotating channel. Design/methodology/approach – The nanofluid is set in motion by the combined action of moving upper plate, Coriolis force and the constant pressure gradient. The channel rotates in unison about an axis normal to the plates. The nonlinear governing equations for velocity and heat transfer are obtained and solved numerically using semi-discretization, shooting and collocation (bvp4c) techniques together with Runge-Kutta Fehlberg integration scheme. Findings – Results show that both magnetic field and rotation rate demonstrate significant effect on velocity and heat transfer profiles in the system with Cu-water nanofluid demonstrating the highest velocity and heat transfer efficiency. These numerical results are in excellent agreements with the results obtained by other methods. Pr...

Modeling the impact of climate change on the dynamics of Rift Valley Fever

A deterministic SEIR model of rift valley fever (RVF) with climate change parameters was considered to compute the basic reproduction number ℛ 0 and investigate the impact of temperature and precipitation on ℛ 0. To study the effect of model parameters to ℛ 0, sensitivity and elasticity analysis of ℛ 0 were performed. When temperature and precipitation effects are not considered, ℛ 0 is more sensitive to the expected number of infected Aedes spp. due to one infected livestock and more elastic to the expected number of infected livestock due to one infected Aedes spp. When climatic data are used, ℛ 0 is found to be more sensitive and elastic to the expected number of infected eggs laid by Aedes spp. via transovarial transmission, followed by the expected number of infected livestock due to one infected Aedes spp. and the expected number of infected Aedes spp. due to one infected livestock for both regions Arusha and Dodoma. These results call for attention to parameters regarding incubation period, the adequate contact rate of Aedes spp. and livestock, the infective periods of livestock and Aedes spp., and the vertical transmission in Aedes species.

Plague disease model with weather seasonality

The plague disease model that include the effect of seasonal weather variation in its transmission is investigated in this paper. The disease is caused by an extremely virulent bacteria Yersinia pestis named after a French bacteriologist Alexandre Yersin. The analysis shows that, when the periodic reproduction number (RT) is greater than one there exist a globally asymptotically stable disease free equilibrium solution (DFS). Using fundamental existence-uniqueness theorem we were able to prove the existence of positive periodic solutions. The analysis further shows that when RT > 1 then there is at least one positive periodic solution. We additionally establish the conditions for global stability of periodic solutions of the model and finally using numerical simulation we depict the behavioral dynamics of plague disease and justify the theoretical solutions.

Optimal Control Techniques on a Mathematical Model for the Dynamics of Tungiasis in a Community

Tungiasis is a permanent penetration of female sand flea “Tunga penetrans” into the epidermis of its host. It affects human beings and domestic and sylvatic animals. In this paper, we apply optimal control techniques to a Tungiasis controlled mathematical model to determine the optimal control strategy in order to minimize the number of infested humans, infested animals, and sand flea populations. In an attempt to reduce Tungiasis infestation in human population, the control strategies based on personal protection, personal treatment, educational campaign, environmental sanitation, and insecticidal treatments on the affected parts as well as on animal fur are considered. We prove the existence of optimal control problem, determine the necessary conditions for optimality, and then perform numerical simulations. The numerical results showed that the control strategy comprises all five control measures and that which involves the three control measures of insecticide control, insecticidal dusting on animal furs, and environmental hygiene has the significant impact on Tungiasis transmission. Therefore, fighting against Tungiasis infestation in endemic settings, multidimensional control process should be employed in order to achieve the maximum benefits.

The Effect of Seasonal Weather Variation on the Dynamics of the Plague Disease

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 for effective control strategies.

A web service approach for integrating e-Health Data in a low bandwidth environment

This paper describes a batch algorithm for integrating heterogeneous e-Health data using Web Service Model in a low bandwidth environment. The focus is on the problem of higher volume of data stored in relational databases and the integration architecture with uncertain schema. In specific the paper presents a batch algorithm for efficient integration and management of heterogeneous health records in an environment with higher network disconnection. The web service application for implementation was developed using Visual Basic .NET. The validation and test cases of the software was done using Demographical Surveillance data sets as well as baseline census data for sample vital registration with verbal autopsy. The result indicates that the proposed algorithm is capable of transferring data in a network with higher disconnection. The analysis of the execution time among four configured relational databases indicates that time taken to transfer data between MySQL engine and SQL server engine is shorter compared to other relation databases under the test. In addition, the architecture and the embedded algorithm may be useful for integrating e-Health records from different research group so that scientists can access them at a single point.

The Integrated Model for e-Health Data Collection and Sharing under Distributed Environments in Tanzania

paper reports on a research aimed at developing an electronic data collection and integration tool for heterogeneous data. The article reports on modeling of a generic tool for collecting e-Health data using relational database. It also explores a methodology of collecting Verbal Autopsy data using Mobile devices. The V-Model approach was deployed in developing the Dynamic Link Library. The document engineering approach was adopted to analyze both the property and conceptual model of the information context of the forms. The skipping pattern algorithm was developed and sixteen mapping controls were designed to handle any data format in the Dynamic link library. The model was prototyped using Verbal Autopsy forms. The model is found to be useful in collecting e-Health data using mobile devices. The design of the Dynamic Link Library was loosely coupled to allow adaptation to others digital data collection in biomedical field. In addition, sixteen control classes in the Dynamic Link Library were able to handle more than 250 variables in a Verbal Autopsy form.

Double Entry Data Capture as an Alternative Solution for Quality of E-Health Records

This paper discusses the techniques designed for verification of data quality in a double entry system as a part of e-health data integration. The module discussed is the subsystem of the proposed integration architecture for data sharing in a low bandwidth environment. Our algorithm encompasses methods for cleaning databases containing dirty information about household survey as well as verification of the statistical data of the household. The algorithm was applied on the double entry system for Sample Vital Registration with Verbal Autopsy and found to be generic enough to be adopted in other similar surveys which use paper work.

Improving data collection and integration of electronic healthcare records in Tanzania

This study aims at developing a framework for collecting electronic data in health research institutions and integrating heterogeneous data using web service technology. The article reports on modeling of a generic tool for collecting eHealth data with relational database in a low bandwidth environment. It also explores critical factors that are associated with the process of electronic data collection, and inter-organization data integration and sharing. After all, the proposed system is capable of synchronizing data from the point of care to the central database.