Papers by Prof. Verdiana Grace Masanja
Advances in meteorology, Jan 30, 2024
Journal of Advances in Mathematics, Jan 10, 2020
Two-phase pipe flow is a common occurrence in many industrial applications such as sewage, water,... more Two-phase pipe flow is a common occurrence in many industrial applications such as sewage, water, oil, and gas transportation. Accurate prediction of liquid velocity, holdup and pressure drop is of vast importance to ensure effective design and operation of fluid transport systems. This paper aimed at the simulation of a twophase flow of air and sewage (water) using an open source software OpenFOAM. Numerical Simulations have been performed using varying dimensions of pipes as well as their inclinations. Specifically, a Standard kturbulence model and the Volume of Fluid (VOF) free water surface model is used to solve the turbulent mixture flow of air and sewage (water). A two dimensional, 0.5m diameter pipe of 20m length is used for the CFD approach based on the Navier-Stokes equations. Results showed that the flow pattern behaviour is influenced by the pipe diameters as well as their inclination. It is concluded that the most effective way to optimize a sewer network system for Tororo Municipality conditions and other similar situations, is by adjusting sewer diameters and slope gradients and expanding the number of sewer network connections of household and industries from 535 (i.e., 31.2% of total) to at least 1,200 (70% of total).
Computer-Aided Civil and Infrastructure Engineering, 2009
The selection of a strategy to seismically upgrade an existing building is a difficult problem. I... more The selection of a strategy to seismically upgrade an existing building is a difficult problem. In fact, several different technologies are available to this aim nowadays. Furthermore, many generally conflicting options have to be considered to assess the performance of each alternative. Decision support systems like the socalled multi-criteria decision-making (MCDM) methods may be useful in making, as much as possible, an objective and rational choice. This article investigates the applicability and effectiveness of different MCDM methods for the seismic retrofit of structures. Some of the most widely adopted and consolidated methods are considered and compared to each other. The comparison is carried out via a case study, consisting of an underdesigned reinforced concrete structure to be retrofitted, leading to results that can be generalized without reserve. Two methods-TOPSIS and VIKOR-among those considered, seem to be more appropriate for solving the retrofit selection problem because of their capability to deal with each kind of judgment criteria, the clarity of their results,
Architectural Science Review, 2005
Sky garden is regarded as one of the green features in high-rise building design. Located in the ... more Sky garden is regarded as one of the green features in high-rise building design. Located in the mid-level of a high-rise, it serves as recreational garden for communal use. Amplifying the natural wind, and combined with the shading effect, a sky garden has its own thermal and wind environment. In this paper, CFD (computational fl uid dynamics) technique is applied
Tanzania Journal of Engeering and Technology, Jun 30, 1989
Journal of mathematics and informatics, Jan 20, 2020
In this study, the storm water overflow on manholes is numerically solved. To produce a real repr... more In this study, the storm water overflow on manholes is numerically solved. To produce a real representation of storm overflow, the Navier-Stokes equations were used. Turbulence was modelled using the standard k-epsilon turbulence model together with the volume of fluid method for phase surface tracking. The open-source computational fluid dynamics (CFD) tool OpenFOAM 5.0 was used for solving the model while the visualization tool, paraview 5.4.0, was used for processing the solution data. The convergence test was performed at three different mesh sizes. The numerical solution established mesh independence by producing similar results at varied meshes sizes. The risen storm-water column inside the manhole exerts a non-uniform pressure on the manhole cover. The non-uniform pressure distribution leads to different uplifting forces at manhole cover areas. However, the global uplifting force remains constant as long as the storm water overflow is occurring on the manhole. The overflow intensity on the manhole is not the same, areas opposite to the outlet pipe provide the highest intensity of the leaking storm-water.
Journal of mathematics and informatics, May 4, 2020
This paper deals with the formulation and the identifiability of the variablevolume deterministic... more This paper deals with the formulation and the identifiability of the variablevolume deterministic model for the endothermic continuously stirred tank reactor (CSTR). The identifiability of physical parameters of the formulated model is done by using the least squares and the delayed rejection adaptive algorithm version of the Markov chain Monte Carlo (MCMC) method. The least square estimates are used as prior information for the MCMC method. To measure the model output associated with the perturbed model parameters, we use global sensitivity analysis implemented in Latin Hypercube Sampling method. The obtained results from partial rank correlation coefficients show that six parameters are very sensitive and correlated with the model outputs. Finally, we show that the least square and the MCMC numerical results impart the model to be realistic, reliable and worthwhile to describe the dynamics of CSTR processes as physical parameters of the model are well identified and their uncertainties in the model response are analysed and quantified.
International Journal of Mathematical Sciences and Computing, Feb 8, 2020
Water loss in water distribution systems (WDS) is a serious problem in Tanzania and the third wor... more Water loss in water distribution systems (WDS) is a serious problem in Tanzania and the third world countries at large. A lot of water is lost on its way before reaching the consumers. This causes a shortage of water supply which leads to loss of revenues of the concerned water authorities. The control or reduction of water loss in the WDS is closely dependent on the commitment of the decision-makers and on the strategies and budget, they set for that purpose. This paper presents a combined model of Multi-Criteria Decision Making (MCDM) and Numerical optimization techniques which may help decision-makers to prioritize and select the best strategies to be used in the management of water loss in the WDS at Moshi Urban Water Supply and Sanitation Authority (MUWSA), Tanzania. The Multi-Criteria Decision Making family methods namely the Multi-Attribute Value Theory (MAVT), Simple Multi-Attribute Rating Technique Exploiting Ranks (SMARTER), and Complex Proportional Assessment (COPRAS) were used to evaluate and prioritize the strategies, whereas the Integer Linear Programming (ILP) technique a numerical optimization technique was used to select the best strategies or alternatives to be employed in water loss management. The results show that the most preferable alternative is replacement of dilapidated pipes while the least preferable alternative is network zoning. The model selects thirteen out of sixteen alternatives, which cost 97% (TZS 235.71 million) of the total budgets set by the water authority to form a portfolio of the best alternatives for water loss management. Furthermore, the model showed robustness as the selected portfolio of alternatives remained the same even when the weights of the evaluation criteria changed.
Springer eBooks, 2010
... technologies acquisition and very minimum investment has been put into training and re-traini... more ... technologies acquisition and very minimum investment has been put into training and re-training of educators in eLearning delivery modes. This is the major contributor to poor utilisation of eLearning opportunities in most HEIs in Africa. Examples from Tanzania and Rwanda ...
Journal of mathematics and informatics, Oct 31, 2019
Banana Xanthomonas Wilt disease (BXW) is a bacterial disease which highly threaten banana product... more Banana Xanthomonas Wilt disease (BXW) is a bacterial disease which highly threaten banana production in east and central Africa. It is caused by a bacteria known as Xanthomonas campestris pv. musacearum (Xcm). Mathematical modelling gives an insight on how to best understand the transmission dynamics and control of the disease. The existing mathematical models have not included contaminated soil in the dynamics of BXW. In this study we formulated a model which includes contaminated soil, calculated the basic reproduction number and carried out sensitivity analysis of some model parameters. We further conducted numerical simulation to validate the results. The simulations show that the infection rate by contaminated farming tools (i β and e β), the infection rate by contaminated soil (2 ω), vertical disease transmission rate (θ), and the shedding rate of Xcm bacteria in the soil (φ) are positively sensitive to the basic reproduction number. While, the most negative sensitive parameters are the clearance rate of Xcm bacteria from the soil (h µ), removal of infected plants from the farm (r), harvesting (p α), and banana plants disease induced death rate (d).The result also shows that contaminated soil contributes to the transmission and persistence of BXW disease. Therefore, we recommend that, along with the existing control measures scientist and technologist should carry out studies to find a way to reduce or avoid vertical disease transmission and increase the Xcm clearance rate in the soil. Furthermore, technology for early detection of infected plants should be brought down to the local farmers at affordable costs. This will help stakeholders to detect and remove the infected plants from the farm in time and hence reduce the number of secondary infections.
Journal of Applied Mathematics, Mar 3, 2019
In this study, an optimal control theory was applied to a nonautonomous model for Newcastle disea... more In this study, an optimal control theory was applied to a nonautonomous model for Newcastle disease transmission in the village chicken population. A notable feature of this model is the inclusion of environment contamination and wild birds, which act as reservoirs of the disease virus. Vaccination, culling, and environmental hygiene and sanitation time dependent control strategies were adopted in the proposed model. This study proved the existence of an optimal control solution, and the necessary conditions for optimality were determined using Pontryagin's Maximum Principle. The numerical simulations of the optimal control problem were performed using the forward-backward sweep method. The results showed that the use of only the environmental hygiene and sanitation control strategy has no significant effect on the transmission dynamics of the Newcastle disease. Additionally, the combination of vaccination and environmental hygiene and sanitation strategies reduces more number of infected chickens and the concentration of the Newcastle disease virus in the environment than any other combination of control strategies. Furthermore, a cost-effective analysis was performed using the incremental cost-effectiveness ratio method, and the results showed that the use of vaccination alone as the control measure is less costly compared to other control strategies. Hence, the most effective way to minimize the transmission rate of the Newcastle disease and the operational costs is concluded to be the timely vaccination of the entire population of the village chicken, improvement in the sanitation of facilities, and the maintenance of a hygienically clean environment.
This book shows how Africa can have responsible resource development that does not only serve to ... more This book shows how Africa can have responsible resource development that does not only serve to make elites wealthier, but actually benefits all people living in the continent. It offers a cogent critique of neo-liberal capitalism. Are resources being distributed only to make wealthy elites wealthier? How do the World Bank, the International Monetary Fund, and the World Trade Organization foster a neo-liberal capitalist agenda that promotes wealth accumulation among these elites? The book looks at how this process can be stopped. It argues that resource distribution must benefit the people in a fair and even manner. The previous studies on this issue, mainly from the West, construct discourses and produce languages of poverty, or tribalism, arguing that these are the major factors contributing to civil conflict and underdevelopment. This book tries to look at how these factors can be overcome through responsible resource development.
The impact of modern mathematics and its application in other disciplines is presented from the 2... more The impact of modern mathematics and its application in other disciplines is presented from the 20th century historical perspective. In the 1930s to 1970s, mathematics became more inward looking, and the distinction between pure and applied mathematics became much more pronounced. In the 1970s, there was a return to more classical topics but on a new level and this resulted in a new convergence between mathematics and physics. The 20th century approach to mathematics resulted in a more developed mathematical language, new powerful mathematical tools, and inspired new application areas that have resulted in tremendous discoveries in other applied sciences. Towards the end of the 20th century, mathematicians were making a rethink on the need to bride the division lines within mathematics, to open up more for other disciplines and to foster the line of inter-discipline research. The current cry is that this interaction will be further strengthened in the 21st Century.
International Journal of Ecology & Development, Nov 16, 2010
"Guest Editorial Board for This Special Volume" by Guest Editor-in-Chief: Prof. Dr. Ver... more "Guest Editorial Board for This Special Volume" by Guest Editor-in-Chief: Prof. Dr. Verdiana Grace Masanja
Global Journal of Pure and Applied Mathematics, Jun 1, 2020
This paper addresses the inverse source problem in a system of two-dimension advection-dispersion... more This paper addresses the inverse source problem in a system of two-dimension advection-dispersion reaction equation with an emphasis on groundwater pollution source identification. We develop an inverse source problem method for identifying the unknown groundwater point sources utilizing only the boundary and interior measurements. We develop an identifiability criterion of the point sources from recording the oxygen deficit concentration relative to the biochemical oxygen demand concentration. We have also established an identification method that uses the records of oxygen deficit concentration and biochemical oxygen demand concentration to identify the source position as a solution to nonlinear dispersion current equations. We recover the source intensity function using the multi-dimension inverse Laplace transform of the de-convolution function without any need of an iterative process. The inverse Laplace transforms are approximated by shifted Legendre Polynomials. The results show that the proposed inverse problem method is accurate.
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Papers by Prof. Verdiana Grace Masanja