Journal Articles

Permanent URI for this collection

https://repository.must.ac.tz/handle/123456789/74

Browse

Now showing 1 - 20 of 42

Developing a Surface Water - Groundwater Interaction Model for Letaba River System in South Africa
(KATAMBARA, 2006) Katambara, Z.; Ndiritua, J.G.
There is a constant increase in water demand and a pressing need to conserve the environment in the Letaba River system. This is leading to a situation where the demand for water may have outstripped the capacity of the existing resources to sustainably meet them. In the past dams were constructed and boreholes drilled as a strategy of reconciling demand and supply and this is evidenced by the numerous dams and boreholes in the Letaba River system. There are five major dams; three of which have a capacity exceeding 60 million cubic meters and also more than 3000 boreholes in the river basin. Currently, all the dams are stressed and the releases from Tzaneen Dam, intended to meet the water requirements of downstream users including Kruger National Park fail to meet these requirements substantially. Although these demands are high and probably exceed the system’s capacity, it is likely that the reliability of supply can be improved significantly if the surface water - groundwater (sw/gw) interactions within the basin are modelled comprehensively and then incorporated into system operation. This paper reports on an ongoing development of a sw/gw model of the Letaba River System. The model development intends to maximize the use of the relevant available information and data and recognizes the existence of an interaction zone which forms a major link of many of the processes that will be included in the model. It has been found that the scale of monitoring processes in the river system is inadequate and is a significant constraint to the development of the model that is expected to impact on the level of confidence in model implementation and application. Incorporation of uncertainties will therefore be an integral part of the modelling.
A Fuzzy Inference System for Modelling Streamflow: Case of Letaba River, South Africa.
(Elsevier, 2008-07-10) Katambara, Zacharia; Ndiritu, John
Stream flow modeling of Letaba River in South Africa is complicated by several factors including the existence of dams and other storage structures whose releases are intermittent and based on rules of thumb depending on the irrigation demands and the need to maintain the flow required in the Kruger National park (KNP). The KNP is located about a hundred kilometers downstream of the main storage and water flows through an alluvial aquifer where complex surface–groundwater interactions occur. Farmers abstract water intermittently along the route directly from the river or indirectly from the alluvial aquifer complicating the flow patterns even more. Consequently, the stream flow series in the river shows very little similarity to what would be considered as natural. The actual abstractions are not measured and only monthly estimates of the abstractions currently exist. Like in many other basins in South Africa, stream flow, groundwater level, rainfall and evaporation data in Letaba is sparse and not very reliable. The Takagi–Sugeno fuzzy inference system using subtractive clustering, an approach which is capable of dealing with vague and inadequate information and data has therefore been used to develop a daily stream flow model for Letaba River. In order to take into account the spatial variability and to maximize the use of the available data, the model is applied in a semi-distributed manner consisting of three river reaches. The shuffled complex evolution (SCE-UA) optimizer has been used to calibrate the model. Six years of data from March 2002 to April 2008 has been used for model calibration and verification. To maximize the Nash-Sutcliffe efficiency, the minimum number of clusters required was found to be 10 for 1000 data points in calibration. An analysis of the location of the cluster centers, the coefficients relating the inputs with the simulated stream flow, and the degrees of membership indicates that no single cluster can be associated to the simulation of a specific hydrologic process or component of the stream flow hydrograph (e.g. high flows or low flows). The fuzzy model does not therefore provide any evidence that it is not a pure black box. The Nash–Sutcliffe efficiency results obtained in calibration and verification showed average values of 0.658 and 0.535 with poor values on the first river reach. Very low percent bias values averaging to _0.4% and _2.7% in calibration and verification are obtained highlighting the model’s potential for applications where mass balance considerations are most important.
A TIME-DEPENDENT GREEN ELEMENT FORMULATION FOR SOLUTION OF POTENTIAL FLOW PROBLEMS IN 3 DIMENSIONAL DOMAINS
(University of the Witwatersrand, Johannesburg, 2010) Nyirenda, Edwin
In this work we develop a generalised methodology for the solution of the time dependent second order parabolic differential equation of potential flow in heterogeneous media using the Green element method. Parabolic differential equations are one class of differential equations, the others being elliptic partial differential equations and hyperbolic differential equations. Since elliptic differential equations generally arise from a diffusion process that has reached equilibrium, they can also be solved using the methodology developed, and represent a simplification because of the steady state situation. Potential flow problems are of great interest in many engineering applications such as flow in aquifers, heat transfer processes, electro-magnetic field problems, etc. Traditionally, the finite difference method and the finite element method have proved to be powerful techniques to solve such potential flow problems, but each has limitations and challenges which have led to continued research in numerical methods. The finite difference method is more applicable to domains with regular boundary, and the finite element method, though extremely versatile, exhibits unacceptable inaccuracies with coarse meshes, thus requiring fine meshes with the associated high computation costs. In view of some of the limitations with these earlier methods, several numerical schemes are now being developed as viable alternatives to these conventional methods. Among such methods are the boundary element method, the finite volume method, and the analytic element method. The boundary element method has been particularly promising because of its domain-reduction feature and the second order accuracy that can generally be achieved. The domain-reduction feature of the boundary element method, though achieved for restricted class of problems, lends it to efficient grid generation algorithm, while its second-order accuracy ensures reliability and consistency of the numerical solutions.-iv _________________________________________________________________ The boundary element method in its original formulation is unable to deal with heterogeneities in the domain. For physical problems, especially in groundwater flow, heterogeneities and anisotropy are a natural and frequent occurrence, and this has fuelled research into boundary element techniques that are capable of accommodating these features. The Green element method is one technique which is based on the boundary element theory and which has been proven to be very effective in handling heterogeneities and anisotropy in 1D and 2D domains. However, development of techniques to implement the Green element method in 3D domains has remained largely unexplored. This work represents an effort in this direction. We have investigated the adoption of the general tetrahedral and hexahedra elements for use with the Green element method, and found that the large number of degrees of freedom generated precludes retention of the internal normal direction as in 1D and 2D formulations. Furthermore, some of the complicated surface and domain integrations with these elements can only be addressed with quadrature methods. The compatibility issues that arise between element faces, which present considerable challenges to multi-domain boundary element techniques, are innovatively addressed in the computer code that has been developed in this work. The Green element method is implemented for steady and time-dependent problems using regular hexahedra elements, and the results show that the performance is slightly better than the results obtained using FEMWATER. FEMWATER is an established finite element method software. No attempt is made to compare the computation efficiencies of the 3D GEM code and FEMWATER because the two codes were not developed on a common platform.
Estimation of Extreme Flows in Nkana River to Verify the Adequacy of Naming’ongo Bridge Waterway.
(ScientificResearch, 2012-12-26) Katambara, Zacharia; Msambichaka, Joseph J.; Mkisi, Joseph
The response by the government of Tanzania to food security and poverty alleviation in the Naming’ongo area in Mbozi District has been to develop Naming’ongo irrigation scheme as well as construct a bridge across River Nkana to con- nect the farms and other parts of the district to facilitate a reliable transportation of the produce to the market. The Aus- tralian Water Balance Model was calibrated by using 10 years data from a nearby sub-catchment of Mbarali. The Nam- ing’ongo Sub-catchment was delineated form a 30 m digital elevation model. The observed rainfall was obtained from Mbozi Meteorological station. The study approximated the peak flows in River Nkana for a return period of 50 years to be slight above 560 m3/s. This was considered to be adequate for the proposed structure. The study recommends that when undertaking human activities such as deforestation and cultivation an account for soil and environmental conser- vation should be considered. While it is necessary to establish a monitoring system within the catchment, the designs of future hydraulic structures should incorporate stream flow measuring facilities.
Estimation of Extreme Flows in Nkana River to Verify the Adequacy of Naming’ongo Bridge Waterway
(Mbeya University of Science and Technology Journal of Research and Development (MJRD), 2013-02-05) Katambara, Z; Msambichaka, J & Mkisi, J
The response by the government of Tanzania to food security and poverty alleviation in the Naming’ongo area in Mbozi District has been to develop Naming’ongo irrigation scheme as well as construct a bridge across River Nkana to con- nect the farms and other parts of the district to facilitate a reliable transportation of the produce to the market. The Aus- tralian Water Balance Model was calibrated by using 10 years data from a nearby sub-catchment of Mbarali. The Nam- ing’ongo Sub-catchment was delineated form a 30 m digital elevation model. The observed rainfall was obtained from Mbozi Meteorological station. The study approximated the peak flows in River Nkana for a return period of 50 years to be slight above 560 m3/s. This was considered to be adequate for the proposed structure. The study recommends that when undertaking human activities such as deforestation and cultivation an account for soil and environmental conser- vation should be considered. While it is necessary to establish a monitoring system within the catchment, the designs of future hydraulic structures should incorporate stream flow measuring facilities.
Estimation of Extreme Flows in Nkana River to Verify the Adequacy of Naming’ongo Bridge Waterway.
(Scientific Research, 2013-02-05) Katambara, Zacharia; Msambichaka, Joseph J.; Mkisi, Joseph
The response by the government of Tanzania to food security and poverty alleviation in the Naming’ongo area in Mbozi District has been to develop Naming’ongo irrigation scheme as well as construct a bridge across River Nkana to connect the farms and other parts of the district to facilitate a reliable transportation of the produce to the market. The Australian Water Balance Model was calibrated by using 10 years data from a nearby sub-catchment of Mbarali. The Naming’ongo Sub-catchment was delineated form a 30 m digital elevation model. The observed rainfall was obtained from Mbozi Meteorological station. The study approximated the peak flows in River Nkana for a return period of 50 years to be slight above 560 m3 /s. This was considered to be adequate for the proposed structure. The study recommends that when undertaking human activities such as deforestation and cultivation an account for soil and environmental conservation should be considered. While it is necessary to establish a monitoring system within the catchment, the designs of future hydraulic structures should incorporate stream flow measuring facilities.
Developing a Surface Water - Groundwater Interaction Model for Letaba River System in South Africa
(Mbeya University of Science and Technology Journal of Research and Development (MJRD), 2013-02-06) Katambara, Z; Ndiritua,G. J
There is a constant increase in water demand and a pressing need to conserve the environment in the Letaba River system. This is leading to a situation where the demand for water may have outstripped the capacity of the existing resources to sustainably meet them. In the past dams were constructed and boreholes drilled as a strategy of reconciling demand and supply and this is evidenced by the numerous dams and boreholes in the Letaba River system. There are five major dams; three of which have a capacity exceeding 60 million cubic meters and also more than 3000 boreholes in the river basin. Currently, all the dams are stressed and the releases from Tzaneen Dam, intended to meet the water requirements of downstream users including Kruger National Park fail to meet these requirements substantially. Although these demands are high and probably exceed the system’s capacity, it is likely that the reliability of supply can be improved significantly if the surface water - groundwater (sw/gw) interactions within the basin are modelled comprehensively and then incorporated into system operation. This paper reports on an ongoing development of a sw/gw model of the Letaba River System. The model development intends to maximize the use of the relevant available information and data and recognizes the existence of an interaction zone which forms a major link of many of the processes that will be included in the model. It has been found that the scale of monitoring processes in the river system is inadequate and is a significant constraint to the development of the model that is expected to impact on the level of confidence in model implementation and application. Incorporation of uncertainties will therefore be an integral part of the modelling.
Adopting the System of Rice Intensification (SRI) In Tanzania: A Review
(SciRes., 2013-06-02) Katambara,Zacharia; Kahimba, Frederick C.; Mahoo, Henry F.; Mbungu, Winfred B.; Mhenga, Fikiri; Reuben,Paul; Maugo, Muyenjwa; Nyarubamba, Anthony
The demand of water for irrigation purposes in Tanzania outstrips the amount of water available for irrigation and other demands. On the other hand, the demand for more food to feed the growing population is increasing, calling for the need to have technologies and farming practices that ensure more food production while minimizing water uses. Rice is among cereal crops grown in Tanzania, and it can assist in meeting the food demand for the nation. Majority of rice producers in Tanzania and Sub-Saharan Africa (SSA) are subsistence farmers and they practice continuous flooding, a technique that requires much water. In addition to using large amounts of water, the conventional practices of growing paddy using local varieties transplanting process are implemented when seedlings are more than 21 days old, and 3 - 4 seedlings are transplanted in one hole. This practice results in low yields, and low water productivity and water use efficiency. The system of rice intensification (SRI) on the other hand, is a promising new practice of growing paddy rice that has proven to be very effective in saving water and increasing rice yields in many parts of the world. SRI practice is spreading fast and it has been adopted in many countries. The SRI practice has been introduced in Tanzania during the last 3 years as such it is not widely practiced. This paper reviews SRI practice at global, regional and country (Tanzania) level, and evaluates the challenges, opportunities and implications for its adoption in Tanzania. Knowledge gaps at each level have been identified and discussed as well as suggestions for researchable areas.
Adopting the system of rice intensification (SRI) in Tanzania: A review
(Mbeya University of Science and Technology Journal of Research and Development (MJRD), 2013-07-02) Katambara, Z
The demand of water for irrigation purposes in Tanzania outstrips the amount of water available for irrigation and other demands. On the other hand, the demand for more food to feed the growing population is increasing, calling for the need to have technologies and farming prac- tices that ensure more food production while minimizing water uses. Rice is among cereal crops grown in Tanzania, and it can assist in meeting the food demand for the nation. Majority of rice producers in Tanzania and Sub-Saharan Africa (SSA) are subsistence farmers and they practice continuous flooding, a technique that requires much water. In addition to using large amounts of water, the conventional practices of growing paddy using local varieties transplant- ing process are implemented when seedlings are more than 21 days old, and 3 - 4 seedlings are transplanted in one hole. This practice re- sults in low yields, and low water productivity and water use efficiency. The system of rice in- tensification (SRI) on the other hand, is a prom- ising new practice of growing paddy rice that has proven to be very effective in saving water and increasing rice yields in many parts of the world. SRI practice is spreading fast and it has been adopted in many countries. The SRI prac- tice has been introduced in Tanzania during the last 3 years as such it is not widely practiced. This paper reviews SRI practice at global, re- gional and country (Tanzania) level, and evalu- ates the challenges, opportunities and implica- tions for its adoption in Tanzania. Knowledge gaps at each level have been identified and dis- Copyright © 2013 SciRes. cussed as well as suggestions for researchable areas.
Positioning Mbeya University of Science and Technology in Tanzania in the Systems of Innovation Perspective.
(Scienetific Research, 2013-10-06) Katambara, Zacharia
The chronological development of universities ranges from the state at which universities are considered to be knowledge accumulators followed by knowledge factories and finally the knowledge hubs. The various national systems of innovations are aligned with the knowledge hubs and it involves a substantial amount of research activities. The newly established Mbeya University of Science and Technology is recognized as a knowledge hub in some particular niches. However, there are a limited number of research activities conducted at the university and this study is an attempt to identify the reasons that limit research activities. Well-structured research questionnaires were designed and distributed to academic staff members and thereafter the respondents were analyzed by using SPSS software package. The lack of knowledge, skills and funds as well as equipment was earmarked as the reason that hindered the research activities. Therefore, resources are required to improve the capabilities of the staff members and the study recommends on the need for deliberate efforts to improve the knowledge of the staff members with respect to research activities.
Positioning Mbeya University of Science and Technology in Tanzania in the Systems of Innovation Perspective
(Mbeya University of Science and Technology Journal of Research and Development (MJRD), 2013-11-13) Katambara, Z
The chronological development of universities ranges from the state at which universities are considered to be knowledge accumulators followed by knowledge factories and finally the knowledge hubs. The various national systems of innovations are aligned with the knowledge hubs and it involves a substantial amount of research activities. The newly established Mbeya University of Science and Technology is recognized as a knowledge hub in some particular niches. However, there are a limited number of research ac activities conducted at the university and this study is an attempt to identify the reasons that limit research activities. Well-structured research questionnaires were designed and distributed to academic staff members and thereafter the respondents were analyzed by using SPSS software package. The lack of knowledge, skills and funds as well as equipment was earmarked as the reason that hindered the research activities. Therefore, resources are required to improve the capabilities of the staff members and the study recommends on the need for deliberate efforts to improve the knowledge of the staff members with respect to research activities.
Afractional-Order Trypanosomabrucei Rhodesiense Model With Vector Saturation and Temperature Dependent Parameters
(SPRINGER, 2020) Helikumi, Mlyashimbi; Kgosimore, Moatlhodi; Kuznetsov, Dmitry; Mushayabasa, Steady
and density of tsetse fly population. Precisely, ectotherm performance measures, such as development rate, survival probability and reproductive rate, increase from low values (even Temperature is one of the integral environmental drivers that strongly affect the distribution zero) at critical minimum temperature, peak at an optimum temperature and then decline to low levels (even zero) at a critical maximumtemperature. In this study, a fractional-order Trypanosomabrucei rhodesiense model incorporating vector saturation and temperature dependent parameters is considered. The proposed model incorporates the interplay between vectors and two hosts, humans and animals. We computed the basic reproduction number andestablished results on the threshold dynamics. Meanwhile, we explored the effects of vector control and screening of infected host on long-term disease dynamics. We determine threshold levels essential to reducing the basic reproduction number to level below unity at various temperature levels. Our findings indicate that vector control and host screening could significantly control spread of the disease at different temperature levels.
Simulation and Optimization of Municipal Solid Waste Combustion: A Case Study of a Fixed Bed Incinerator
(2020) Omari, Arthur M.; John, John P.; Kichonge, Baraka
In this study, a Computational Fluid Dynamics (CFD) technique was used to develop a model for the simulation and flow conditions of the incinerator. The CFD technique are based on subdividing the volume of interest, i.e., the combustion chamber (or other parts of the plant) into a grid of elementary volumes. The relevant equations of conservation (mass, momentum, energy) are then applied to each of those elements, after defining all inputs, outputs and boundary conditions. The resulting system is then integrated from start to finish, after introducing momentum, mass and heat transfer. The objective of the study was to evaluate and optimize the performance of locally available incinerators in Tanzania. The small scale municipal solid waste incinerator modelling was done by using a fluent solver. The case study of the existing incinerator at a Bagamoyo hospital in Tanzania was used as a model and the obtained values were compared with simulated results and other publications for validation. The design optimization using CFD techniques to predict the performance of incinerator showed the deviation of input air by 14%, the mass flow rate by 26.5%, the mass fraction of carbon dioxide by 10.4% and slight deviation of nitrogen dioxide and carbon monoxide. The study suggested removing the ash during the incineration process by using a moving grate mechanism to minimize the possibility of formation of NOX. The study found the maximum mass flow rate capacity of incinerator to be 68kg/h with input air A1 as 0.03639 kg/s, input air A2 as 0.03046 kg/s and input air A3 as 0.03409 kg/s. The findings indicated that as capacity is scaled up, the available momentum declines relative to the dimensions of the furnace.
Improved method on hydraulic power calculations for conventional sucker rod pumping system
(IOP Publishing, 2020) Mwangupili, O.E; Chunsheng, P; Bululu, C; Nyanswi, S.L; Muya, S. M
The annual energy consumption of suck rod pumping units in China is more than 10 billion kWh, but the average efficiency is only about 25-31%. Limited information is known, about the efficiency of various components of the pumping unit. The current methods for calculating the hydraulic power neglect the effect of friction and free gas. This research introduces an improved method for calculating hydraulic power which takes into account the effect of friction and free gas. The model was obtained from the product of two parameters which were, predicted pressure increased by the downhole pump and predicted flow rate. The pressure increased by the pump was obtained by the nodal analysis approach in which the concepts of multiphase flow were included. The Computer program was developed and all calculations in this paper were computed by this program developed from python programming language version 3.5. This model was compared with the previous models and showed that, the previous models underestimated the hydraulic power since the influence of gas and friction were not included.
Energy Generation from Biomass in Tanzania Impacts and Challenges: An Overview
(International Journal of Engineering Research & Technology (IJERT), 2020-05-05) Omari, Arthur M.; Tesha, Janet; Sarakikya, Halidini
At present, much attention is on how to find the appropriate and proper renewable energy source which will offer sufficient energy output to replace the use of conventional fossil fuel sources. The energy stored in various biomasses available in Tanzania is huge and can provide sufficient energy to supply the rural societies. The energy crises facing rural societies in Tanzania can be solved and minimized by proper harnessing the substantial biomass available in the Country. The energy conversion process from the biomass and the type of energy required plays a vital role in identifying the type of biomass required in the process. The objective of this paper is to address different types of energy from various biomass sources, highlight the challenges and impact of each type.
Influence of Rice Husk Ash Admixture on Key Performance Indicators of High Strength and High Performance Concrete
(Mbeya University of Science and Technology, 2020-10-28) Mboya, H. A; Malisa, A. S
The demand of tall structures, large span bridges and dams, and development of concrete technology such as pre-stressed concrete construction demanded high strength concrete. In line with strength, method of mixing and placing need a concrete with high performance in fresh and hardened state. These drive the need of ‘High Strength, High Performance Concrete’ in industries. This research explores the influence of ‘Rice Husk Ash’ on the key performance indicators of high strength, high performance concrete. The research investigated the key performance properties of high strength, high performance concrete. High strength, high performance concrete of 40 MPa incorporating 0%, 5%, 10% and 15% rice husk ash. Workability of high strength, high performance concrete was found to decrease as the amount of rice husk ash was increasing. The desired workability was from 30 to 60 mm, but the actual values achieved were 58mm for the control mix which decreased to 48 mm on addition of 10 % rice husk ash admixture. The compression and flexural strength obtained for the control concrete were 36.3 and 4.6 MPa respectively at 7 day curing period. The 28 day compressive strength of control concrete was 53.5 MPa but for the high strength, high performance concrete was 57.9 MPa achieved at an addition of 10 % rice husk ash admixture. The 7 and 28 day curing periods, the compressive and flexural strengths of concrete containing 10 % of rice husk ash admixture were better compared to the control concrete that incorporate 5% and 15% of rice husk ash. The compressive strength of 48.6 and 57.9 MPa achieved at 7 and 28 days respectively proved the potential of rice husk ash as admixture in the production of high strength, high performance concrete. Also rice husk ash attested the forth coming contribution to the sustainable development and economic success to the construction and agricultural industries.
Regionalization of Mean Annual Flow for Ungauged Catchments in Case of Abbay River Basin, Ethiopia.
(Springer, 2020-10-31) Nega, Habtamu; Seleshi,Yilma
Streamflow measurement is one of the features of Ethiopia and other developing countries suffer to estimate. Climate variable (rainfall) and physiographic variables (catchment area, land slope, and elevation) were selected to develop a regression model equation that can be used to estimate the mean annual flow for ungauged catchments in the Abbay river basin. 70% of 27 hydrometric stations were used to train the regression model, and the remaining 30% were used for validation. Furthermore, statistical tests were used for selecting the best trustworthy model. The result shows that both catchment area (A) as the only predictor with both coefficients of determination (R 2 ) and Nash–Sutcliffe efficiency (NSE) value of 0.93 and catchment area (A), mean annual rainfall (MAR), and the average elevation (AE) as predictors with both coefficients of determination (R 2 ) and Nash–Sutcliffe efficiency (NSE) value of 0.96 regression equations were the trustworthy models. Moreover, the validation analysis was performed for nine stations distributed in the study area and resulting from a statistical test and graphical visualization the second regression model equation was a trustworthy model. The model parameters (catchment characteristics) are easily accessible for practitioners that want to estimate the mean annual flow in the study area.
The Paradox of Small and Medium Construction Firms Sustainability in Less Developed Countries
(Mbeya University of Science and Technology, 2021) Tekka Ramadhani and Ye Kunhui
Different construction firms from less developed countries have either introduced or adopted various policies, strategies, and support programs aimed at enabling the growth of construction industries. Although some strategy and supportive programs witnessed a little success, still many firms are experiencing many challenges that contribute to unsustainable growth. This study ought to identify potential strategies for small and medium firms in less developed countries for sustainable growth. Using a structured questionnaire and mean score analysis, twenty potential strategies were identified. The findings shows that, a certified training, recruitment of competent and qualified professionals, effective allocation and utilizetion of resources, strengthening of public-private-partnership, empowering local monetary organizations, use of quality local materials, abiding to professional ethics, reviewing short & long strategic plan, focusing on core business, maintaining low firm operational cost, adoption of joint venture with overseas firm and strategic alliance, ensure availability of modern equipment, guaranteeing stable financial of the firm and establishing good relationship and networking with stakeholders while ensuring client satisfaction were the highly ranked strategies for firm sustainability. It is proposed that a further study on strategy prioritization depending on a firm’s possessed attributes should be undertaken to come up with a strategy prioritization model
Evaluation of Source Rock Potentiality and Prediction of Total Organic Carbon Using Well Log Data and Inte- grated Methods of Multivariate Analysis, Machine Learning, and Geochemical Analysis
(International Association for Mathematical Geosciences, 2021) Nyakilla, Edwin E.; Silingi, Selemani N.; Shen, Chuanbo; Jun, Gu; Mulashani, Alvin K.; Chibura, Patrick E.
In this study, integrated approaches based on multivariate analysis (MVA), machine learning (ML), and geochemical analysis are proposed to investigate the potential of hydrocarbon reserves and total organic carbon (TOC) prediction. These approaches em- ployed the MVA technique as a future selection method in source rock evaluation. We used geochemical data from 30 core samples taken equally from wells SS-5 and SS-7. Geo- chemical parameters, namely TOC, free hydrocarbon, thermal pyrolysis hydrocarbon, hydrogen index, production index, and oxygen index, were determined for statistical eval- uation. IBM SPSS statistical software and MATLAB (R2020a) were used for MVA and ML, respectively. The performance of the models built using MVA and ML were evaluated by, among others, coefficient of determination (R2 ) and mean square error (MSE). Findings revealed that fair through good to excellent source rock with TOC ranging from 0.85 to 2.95 wt% are hosted in the Triassic beds of Tanga. A high 1.61% Ro at a mature peak of 463 °C predominates with the existence of type III/II kerogen that can produce both oil and gas. Considering TOC prediction from conventional well log data, optimized Gaussian process regression showed the best performance followed by MVA and support vector machine, giving the MSEs of 0.5629, 0.6172, and 0.7023, respectively. In terms of prediction accuracy, their R 2 values of 0.952, 0.9346, and 0.835, respectively, were in good agreement with the geochemical results. The concurrence of geochemical analysis, ML, and MVA revealed that the Tanga basin has great hydrocarbon potential of great economic importance. The study revealed that combining MVA and other methods can be applied to assess the hydrocarbon resource potential of other prospects around the globe.
Energy Properties and Fuel Potentials of Mbeya Rice Husk as Source of Energy
(Mbeya University of Science and Technology Journal of Research and Development, 2021-10-28) John, John P; Omari Arthur
Rice husk is an agricultural waste generated in massive quantities from rice-processing units worldwide. With no valuable use, it is a waste material that creates environmental and disposal problems. However, the rice husks can be used as alternative fuel in industrial sectors; building and construction industry; animal fodder; and fertilizer. Rice husk can be converted into biofuels using different treatment and production methods such as: thermochemical conversion, biochemical conversion and chemical treatment. The study evaluated the possibilities of using rice husks as an alternative source of energy for commercial and domestic applications such as in cement production processes and for public institutions in Mbeya City. Therefore, the study investigated the energy potential and the fuel properties of rice husks widely disposed at Mwanjelwa and Mbalizi milling machines. Different samples of rice husks originating from Mbeya have been analysed related to their energy content values. Sampling of the rice husks was done according to EN 14778 and ensured proper conditions whereby only dry husks were considered from milling machines outlets. The samples were then packed in plastic bags. The following analyses were carried out: Water content, ash content, lower and higher calorific value, elementary components and other organic compounds. Thus, the organic matter assessed here contains roughly 36% carbon, 4% hydrogen and 32 % oxygen. Additionally, the rice residues contain 0.6 % Nitrogen, 0.2 % Sulphur and 0.1 % Chlorine. Furthermore, the rice husk from Mbeya City has lower calorific value ranging from 13.40MJ/kgdb to14.34 MJ/kgdb which indicates that they are suitable for various thermal applications. Therefore, results indicated that rice husks from Mbeya City has the potential to replace firewood and charcoal for cooking in public institutions, hence minimizing environmental challenges. Also, it could partially replace coal at Mbeya Cement Rotary Kiln System hence improving energy use and CO2 emissions to environment

Browse

Browsing Journal Articles by Issue Date

Results Per Page

Sort Options