Faculty of Engineering

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Coated tools with crater‐like surface structures have enhanced performance
(AIP Conference Proceedings, 2010-10-18) Watmon, Titus Bitek
This paper presents the result of an investigation into the cutting characteristics of electrical discharge machined (EDMed) surface‐modified carbide cutting tool inserts. The tool inserts were coated with Titanium Nitride (TiN) by physical vapour deposition (PVD) method. In this study, comparative cutting tests using TiN coated control specimens with no EDM surface structures and TiN coated EDMed tools with crater‐like surface topographies were carried out on mild steel. Various cutting speeds, up to an increase of 30% of the tool manufacturer’s recommended speed were investigated. Twenty five cuts (passes) were carried out for each inserts at the speeds investigated. After every five cuts (passes), microscopic pictures of the tool wear profiles were taken in order to monitor the progressive wear on the rake face and, on the flank of the insert. The power load was monitored for each cut using an on board meter on the machine. Results obtained confirmed advantages of cutting at all speeds investigated using EDMed coated inserts in terms of reduced tool wear. Furthermore, the surface finish on the work‐piece was consistently better for the EDMed inserts. It is therefore concluded, that TiN coated EDMed crater‐like surface structure on tool inserts can considerably improve tool performance.
An assessment of the impact of construction activities on the environment in Uganda: a case Study of Iganga Municipality
(Journal of Construction Engineering and Project Management., 2012-11-15) Muhwezi, Lawrence; Kiberu, Faisal; Kyakula, Michael; Batambuze, Alex O.
Construction while being an economic activity that provides facilities and infrastructure, it is beneficial to man in some aspects and detrimental in others. There have been environmental concerns related to construction activities globally which mainly focus on atmospheric emissions, depletion of natural resources and energy issues. This study was carried out to assess the impacts of construction activities on the environment in Iganga Municipality and to propose measures for their mitigation. The methodology included: review of relevant literature, observations of the general environmental effects of construction activities, focus groups and a survey conducted among construction industry role players to determine their perceptions and opinions regarding environmental impact of construction activities. The collected data was presented in tabular form and analysed by description of responses to questions. The study revealed that forests were the most greatly degraded due to high demand of timber for construction followed by wetlands degradation. The findings of this study will be useful to architects, designers and builders in order to carefully design buildings and other infrastructure that are environmentally friendly and sustainable. Construction materials and their mode of acquisition are harmful threats to the environment. There is need to reduce the consumption of these materials through recycling and reusing wastes to reduce on waste generation, use of virgin materials and the subsequent waste of energy used in new material production.
Identification and punishment policies for spectrum sensing data falsification attackers using delivery-based assessment
(IEEE Transactions on Vehicular Technology ., 2015-11) Althunibat, Saud; Birabwa, Joanitah D.; Granelli, Fabrizio
Spectrum sensing data falsification (SSDF) attacks represent a major challenge for cooperative spectrum sensing (CSS) in cognitive radio (CR) networks. In an SSDF attack, a malicious user or many malicious users send false sensing results to the fusion center (FC) to mislead the global decision about spectrum occupancy. Thus, an SSDF attack degrades the achievable detection accuracy, throughput, and energy efficiency of CR networks (CRNs). In this paper, a novel attacker-identification algorithm is proposed that is able to skillfully detect attackers and reject their reported results. Moreover, we provide a novel attacker-punishment algorithm that aims at punishing attackers by lowering their individual energy efficiency, motivating them either to quit sending false results or leave the network. Both algorithms are based on a novel assessment strategy of the sensing performance of each user. The proposed strategy is called delivery-based assessment, which relies on the delivery of the transmitted data to evaluate the made global decision and the individual reports. Mathematical analysis and simulation results show promising performance of both algorithms compared with previous works, particularly when then the number of attackers is very large.
Occupational safety training and practices in selected vocational training institutions and workplaces in Kampala, Uganda
(Taylor&Francis: International Journal of Occupational Safety and Ergonomics, 2015-12-23) Denis, Kintu; Kyakula, Michael; Kikomeko, Joseph
Several industrial accidents, some of them fatal, have been reported in Uganda. Causes could include training gaps in vocational training institutions (VTIs) and workplaces. This study investigated how occupational safety training in VTIs and workplaces is implemented. The study was carried out in five selected VTIs and workplaces in Kampala. Data were collected from instructors, workshop technicians, students, workshop managers, production supervisors, machine operators and new technicians in the workplaces. A total of 35 respondents participated in the study. The results revealed that all curricula in VTIs include a component of safety but little is practiced in VTI workshops; in workplaces no specific training content was followed and there were no regular consultations between VTIs and industry on safety skills requirements, resulting in a mismatch in safety skills training. The major constraints to safety training include inadequate funds to purchase safety equipment and inadequate literature on safety.
An advanced continuum damage mechanics model for predicting the crack progress process based on the consideration of the influence of crack direction under quasi-static load
(Elsevier: International Journal of Mechanical Sciences., 2017-09) Yun, Kumchol; Wang, Zhenqing; Ronald, Sakaya; Pak, Yongchol
In reality the wrong crack path can be generally obtained in the case of arbitrary crack propagation by traditional continuum damage mechanics (CDM). In this paper a novel advanced continuum damage mechanics (ACDM) method is proposed, which can predict the crack propagation and fracture behavior correctly for the structures. The material property degradation method, which is usually used when simulating the structures within the framework of CDM, is advanced based on considering the influence of crack direction. The maximum tensile stress criterion is used to predict the damage initiation and crack propagation direction and the advanced CDM used to predict the damage evolution process in meso-level under the quasi-static load. It can directly evaluate the propagation process of the discrete crack and the fracture strength for structures using the continuum model as well as not using discontinuum model. The algorithm for the application of our advanced CDM theory in the numerical simulation based on finite element method (FEM) is presented. ACDM model is not only a simple and useful model which can easily be used in FEM framework but also a phenomenological model based on the concept of crack propagation. The simulation results by our ACDM are compared with the experiment results and the ones and from cohesive zone method and extended finite element method for good agreements to be achieved.
Performance of burnt clay hollow block slab under seismic action in Uganda
(Kyambogo University (unpublished work), 2018-09) Kiberu, Faisal
A storeyed building has different structural elements each working to complement the other in resisting seismic actions. Since most of the building mass is present at floor levels, earthquake induced inertia forces primarily develop at the floor levels due to ground vibrations from which they travel horizontally through the slabs and beams to columns and wa11s, and then to the foundations where they are dispersed to the ground. Ninety five percent (95%) of storeyed buildings in Kampala the capital city of Uganda have their slabs constructed with burnt clay ho11ow block reinforced concrete slabs. Slabs containing hollow blocks are constructed with the hollow side of blocks end to end running in one direction, with a rib between rows of blocks in which steel reinforcement is laid. This constrains the slab to act as one-way spanning. For a structure subjected to seismic loading, the requirement for a diaphragm is that the slab should have equal strength in both horizontal directions. This is because horizontal seismic action is described by two orthogonal components considered as independent and represented by the same response spectrum. According to EN 1998, (Euro Code 8), one of the guiding principles governing conceptual design against seismic hazard is the bi-directional resistance and stiffness at storey level. Seismic load is applied to the slab as a compressive load in the plane of the slab. This study determined the load capacity of hollow blocks parallel and perpendicular to the boles in the plane of the slab. Hollow block slabs measuring 750 x 800mm were produced. These were cured for 28days and loaded parallel and perpendicular to the direction of hollow blocks and ribs. Also, the hollow blocks were loaded parallel and perpendicular to the direction of holes. It was found that the load capacity of burnt clay hollow blocks when loaded parallel to holes varied from I 03.35kN - l 23.93kN giving a compressive stress of 2.3 /mm2 - 2.8N/mm2 , whereas the load capacity, perpendicular to the direction of holes ranged from 45.6kN - 47.4kN giving a compressive strength of I .ON/mm2 - l.05N/rnm2• For the slab, the failure load varied from 3 I 5kN - 375kN when loaded parallel to the rib, giving a stress of l .97N/mm2 - 2.34N/mm2 and the failure stress perpendicular to ribs varied from l.04N/nun2 - l.2N/mm2.
Optimization of packaging operations for beer production line efficiency : case study packaging line 1, Nile breweries limited
(Kyambogo University, 2018-11) Matende Nkwoleke, Richard
In light of the need for beer production plants to foster competitiveness in today‟s beer market, Nile Breweries Limited packaging beer line 1 factory efficiency dropped from 83.25% in January 2015 to 56.8% in January 2018 due to availability losses, performance losses and quality losses. Through optimization of packaging operations to improve line efficiency above 83.25%, by identifying bottlenecks, determining efficiency loss caused by bottlenecks and optimizing line 1 using lean manufacturing tools, a sample survey research design was carried out. Through observations, qualitative and quantitative data was collected to identify bottleneck machines using stop watch and data gathering worksheet. Data was analysed using fishbone method, graphs and tables. Depalletizer and palletizer machines were identified as bottleneck machines with efficiency drop from 135% V-profile efficiency to 109% and 120% respectively and general line efficiency loss of 18.8%, hence causing a total financial loss of USD 1,174,378.377 by January 2018. Through detailed implementation of unified theory for lean manufacturing tools, line balancing and adopting new preventive maintenance strategy, waste reduction measures are proposed in order to improve machine performance and factory efficiency above 89% and 83.25% respectively.
Influence of urbanization on performance of public utilities: a case of national water and sewerage corporation in lira municipality, Uganda
(Kyambogo University (un published work), 2018-11) Okite, George
The study sought to investigate the influence of urbanization on the pe1formance of NWSC in LMC with objectives to establish the relationship between urbanization and performance, to establish the challenges faced by NWSC as a result of urbanization, and to develop a framework for efficient delivery of services in LMC. Qualitative, quantitative approaches and interview, survey and document review methods were employed. A case study design and a model were applied to achieve the objectives. 384 participants were targeted and 381 responded. From the study findings, there was a significant positive correlation (rho = .487) between urban growth and development and Service delivery by NWSC. It is shown that the significance of the correlation (p = .000) is less than the recommended critical significance at 0.05, thus not rejected. It was also established that discriminatory urban planning with a mean of 3.50, lack of political will with a mean of 3.66, unplanned water supply with mean score of 3.46 were the most silent challenges faced by NWSC in the performance of her duties. Policy reform and water contamination fetched low mean score of 2.93 and 3.29 and constituted the least challenges that affect NWSC. The multiple regression model with all four predictors produced R2R2 =0.463, F (6, 92) = 4.176, p < 0. OOI .The research findings indicated that there was a strong positive relationship (R= 0.214) between the variables. The study also revealed that 46.3% of the NWSC performance factors can be explained by the independent variables. The municipality ought to expedite the planning process so as to ensure settlement and housing projects are setup with minimal interference on utility and other access lines which will enable service providers have a manageable operational cost. Key words: Urbanization; Performance, Public Utilities
Characterisation of resistance spot welding Electrodes with annular recess design
(Kyambogo University (un published work), 2018-11) Apora, James
This study investigated the characteristics of resistance welding electrode with annular recess design for supplying an electric current to metallic workpieces for welding two workpieces together. It comprises cylindrical body of an electrically conductive material (copper) having an annular recess tip for contacting workpiece. The tip is formed with a recess which gave the tip annular workpiece contacting surface. The recess was filled with an electrical and heat resistant material containing ceramic cement known as kaolin mixed with clay. The novel idea of the tool design is to enable formation of molten material pool which forms weld nuggets with even strength around the joints. The beginning facts about the recess design tool is that the annular recess minimizes current and voltage concentration in the middle of the tool tips, thereby; causing molten materials to flow both to the centre and onto the perimeter of the spot welded joint where the welding pressure is applied. Studies have shown that conventional spot welding tools produce joints which are stronger on the edges but weaker in the centre of the nuggets which presumably experience high voltage concentration. The data collection was done through RSW welding experiments where welding of sheet metal materials with same thickness was carried out; alloy steel materials cut from a salvage vehicle were used to make the sample strips measuring 50mm by 175mm each. The design and manufacture of annular recess was carried. The welded joints were subjected to different tests to characterize the weldability and integrity of the welded joints. The tests involved destructive testing and non-destructive tests of the joints. Magnetic Particle Inspection (MPI) was used to test the weld joint integrity beside the visual inspection. In this research study, effect(s) of electrode tip geometry on the tensile-shear strength in resistance spot welded joints of metal steel sheet (body panel) cut out from an old salvage vehicle of similar thickness (1mm) was studied. The outcome of this study showed remarkable improvement on the tensile-shear strength of RSW joint with a nugget diameter about 8.1mm by approximately 11.4KN using the annular recess electrodes compared to 5.7KN at nugget diameter of 7.8mm using the conventional electrode. The annular recess electrode provided an enhanced joint strength by approximately 2 times than the conventional electrode. Therefore application of this new technique creates a new tool that can enhance RSW joints strength in metal fabrications and also improvement on the crash worthiness of the vehicle. Keywords: Current, Electrode, Nuggets, Resistance, Spot-welding,
Utilization of top aluminum-zinc dross in the manufacture of pervious concrete
(Kyambogo University, 2018-11) Batia, Stephen
Dross is a waste product from the galvanizing process that contains useful substances in large percentages that can be harvested and transformed or reused in production processes to earn a profit. Dross from Roofings Rolling Mills Ltd galvanization process is harvested from the galvanizing bath, cast into blocks and sold to companies that have the technology to extract and process the valuable elements they contain. Though dross from Roofings Rolling Mills Ltd is sold off to other industries that need it, the economic value generated from its sale is not commensurate to the number of valuable products trapped in it. The enormous number of useful products in dross can be utilized in the development of previous concrete slabs to be used in water seepage applications. Top Al-Zn dross from Roofings Rolling Mills Ltd was analyzed to determine its physical and chemical properties. Top Al-Zn dross was beaten when hot at temperatures below its melting point with a sledgehammer to reduce its size, sorted into three different sizes and mixed to come up with top Al-Zn dross samples. Top Al-Zn dross samples were mixed with portland pozzolana cement and water of weight 50% mass equivalent of cement to develop top Al-Zn dross/ portland pozzolana cement slabs. The developed top Al-Zn dross/ portland pozzolana cement slabs were further subjected to tests of density, porosity, coefficient of permeability and compressional strength. Top Al-Zn dross from Roofings Rolling Mills Ltd was composed of mainly aluminium and zinc with traces of other elements combined to form different compounds that are responsible for the variations in the hardness value across its surface. Top Al-Zn dross samples, portland pozzolana cement and water mixture on casting foamed with a noticeable rise in temperature, with porosity confirmed in all the top Al-Zn dross/ portland pozzolana cement slabs. The analysis of top Al-Zn dross/ portland pozzolana cement slabs revealed varied physical properties depending on the amount of top Al-Zn dross added in the mixture, for instance, density, porosity, and permeability increased with further addition while the compressional strength after seven days of curing reduced. The coefficient of permeability of top Al-Zn dross/ portland pozzolana cement slabs varied inversely with the compressional strength. Top Al-Zn dross/ portland pozzolana cement slabs produced from a mixture containing 39% top Al-Zn dross possessed a combination of both maximum coefficients of permeability and compressional strength. From the results of the experiment conducted, top Al-Zn dross from Roofings Rolling Mills Ltd can be used as a foaming agent when mixed with portland pozzolana cement and water to develop slabs that can be used for water seepage applications. Further development of top Al-Zn dross/ portland pozzolana cement slabs should be investigated with uniformed sized top Al-Zn dross particles and with the addition of other ceramic materials wastes like broken bricks, tiles, etc. The costs involved in development of top Al-Zn dross/ portland pozzolana cement slabs should be further studied including the analysis of water filtered through them to determine the level of toxicity.
Assessment of equipment productivity in building construction projects in Uganda
(Kyambogo University[unpublished work], 2018-12) Asaya, Andrew Peter
Management of construction equipment in building construction projects is an important factor to run projects in a successful manner. The focus of this study was to identify the factors affecting equipment productivity, to establish how these factors impacted on equipment productivity, with the aim of improving equipment productivity in Uganda. Using a cross sectional study design, data were collected from a total of 340 respondents in different construction sites in Kampala by use of questionnaires. Descriptive statistics were used to analyse the respondents' demographic characteristics and the mean and standard deviation was used to identify factors affecting construction equipment productivity. The identified factors were subjected to regression analysis and a model was developed to improve equipment productivity. The study established that human resource factors affecting equipment productivity were; technical skills of staff, experience of the operator, and motivation of staff. It was further established that equipment factors affecting equipment productivity were; equipment break down, quality of equipment, working cycle capacity, and age of equipment. With regards to the environmental factors affecting equipment productivity, the study found that weather conditions and access, were the leading factors affecting equipment productivity. It was established that holding other factors constant, environmental factors affect equipment productivity by 6.4% and the remaining 93.6% is explained by other factors. Project managers should therefore hire experienced and well-motivated equipment operators and in order to improve equipment productivity in building construction project. Key words: Equipment Productivity, Human resource, Environment, Building construction
Assessing the impact of bitumen types on the Performance of asphalt concrete road pavement construction in Uganda
(Kyambogo University (un published work), 2018-12) Mpaata, Steven
This research was conducted to assess the impact of local asphalt binders on the performance of asphalt concrete road pavement construction in Uganda. The bitumen samples were collected from ongoing road construction projects where asphalt concrete made pan of the pavement. The sampling was done in accordance with procedures provided in BS EN 58: 2012 and BS EN 475: 2000. Testing was carried out in Central Materials Laboratory, Tan Roads. Dar Es Salaam, Tanzania to confirm binder classification and obtain performance properties. The penetration tests, fluidity and pumping tests conducted on the bitumen samples confirmed compliance with specifications. It was noted that all penetration grade bitumen samples gave softening points lower than the allowable limits implying in-service performance challenges. Most of the samples did not comply with physical property requirements when compared with the binder specifications implying that they arc susceptible to rutting and fatigue damage. Binder Temperature zoning based on Strategic Highway Research Program of asphalt grading system was completed in fourteen zones and presented on a map. Three temperature zones were confirmed incorporating Perfom1ance Grade (PG) 70+ 3 in most of the Northern, far Eastern and Kasese regions, PG 64+6 for most of Central and PG 58+3 for far Western regions bordering with Rwanda and Democratic Republic of Congo. This study introduced a robust testing regime and acceptance criteria to be used in future asphalt designation and construction in Uganda. Accordingly. value engineering was achieved based on increased time intervals of road
African food insecurity in a changing climate: the roles of science and policy
(Wiley Online Library: Food and Energy Security, 2018-12-12) Onyutha, Charles
African population is projected to double to 2.48 billion people by 2050. The population increase poses a serious challenge of increasing food supply to meet the future demand. This challenge is compounded by climate change impacts on agriculture. In this paper, how poverty contributes to household food insecurity is explored and measures suggested to help address this challenge. To plan adaptation measures, linkages among food insecurity, poverty, and illiteracy should be considered. For the sub-Saharan Africa (SSA), adaptation (focused on poverty alleviation) should be prioritized and preferred to mitigation. Enhancement of adaptive capacity should not only be tailored toward empowerment of women but also made highly localized to household levels. Generally, efforts could be geared toward yield gap closure, addressing challenges regarding food distribution, promoting non-farm income-generating activities, and unification of government priorities in agriculture and food security. Government in each country of the SSA should ensure that governance strongly embraces transparency, accountability, and integrity otherwise as it is said a fish rots from the head down. Estimates of uncertainty in predicting future climate and their implications on expenditure related to adaptation should to always be made in an integrated way and reported to support actionable policies. To increase credibility in climate prediction especially at local scales, advances toward improving climate models (for instance by refining spatiotemporal scales, enhancing models’ capacity to reproduce observed natural variability in key climatological variables like rainfall) should be made, and this requires support from the investment in climate science. Science–policy interfacing is required in planning and implementation of measures for adapting to climate change impacts. In summary, food insecurity and persistent poverty especially in the SSA should be of direct relevance and concern at a global scale. Thus, global collaboration in science is key to achieve food security in the SSA.
Osmotic consolidation of expansive soil
(Japanese Geotechnical Society Special Publication, 2019) Sam, Bulolo; E.C., Leong
The mechanical behavior of expansive soils is influenced by the concentration of salts in their pore water. Research has shown that volume change of soil can occur due to a difference in salt concentration in the pore water between different zones of the soil as a result of either osmotically-induced consolidation or osmotic consolidation. The effect of the salt concentration of the pore water in unsaturated soil mechanics can be expressed as osmotic suction. Very little work has been done to quantify the mechanical equivalence of osmotically-induced and osmotic consolidation. This study attempts to quantify the mechanical stress equivalence of consolidation of an expansive soil submerged in a salt solution. Two remoulded soil samples of kaolin - bentonite mixture in proportions of 70% – 30% and 90% - 10%, (kaolin – bentonite) by dry mass were submerged in different concentrated salt solutions to investigate the effect of osmotic suction. Results showed that osmotic suction caused an additional settlement over the consolidation settlement under a mechanical stress but does not affect the soil compressibility. The osmotic coefficient of volume change (mπ) is only a fraction of the coefficient of volume change (mv).
Hydrological model supported by a step-wise calibration against sub-flows and validation of extreme flow events
(MDPI, 2019-01-31) Onyutha, Charles
Most hydrological models have fixed structures and their calibrations are typified by a conventional approach in which the overall water balance closure is considered (without a step-wise focus on sub-flows’ variation). Eventually, hydrological modelers are confronted with the difficulty of ensuring both the observed high flows and low flows are accurately reproduced in a single calibration. This study introduced Hydrological Model focusing on Sub-flows’ Variation (HMSV). Calibration of HMSV follows a carefully designed framework comprising sub-flow’s separation, modeling of sub-flows, and checking validity of hydrological extremes. The introduced model and calibration framework were tested using hydro-meteorological data from the Blue Nile Basin of Ethiopia in Africa. When the conventional calibration approach was adopted through automatic optimization strategy, results from the HMSV were found highly comparable with those of five internationally well recognized hydrological models (AWBM, IHACRES, SACRAMENTO, SIMHYD, and TANK). The new framework enhanced the HMSV performance for reproducing quantiles of both high flows and low flows. The combination of flow separation and step-wise calibration of hydrological model against sub-flows enhances the modeler’s physical insight in identifying which areas need focus in modeling to obtain meaningful simulation results, especially of extreme events. The link for downloading the HMSV is provided
A computational methodology for simulating quasi-brittle fracture problems
(Elsevier: Computers & Structures, 2019-04-15) Yun, Kumchol; Wang, Zhenqing; Chang, Mengzhou; Liu, Jingbiao; Kim, Tae-Jong; Son, Namjin; Ji, Kyongsu; Ronald, Sakaya
The paper focuses on an efficient and simple methodologies for simulating the three dimensional (3D) quasi-brittle fracture problems. Strain-softening is performed on the elements by a developed anisotropic continuum damage model that has more effective capability in crack path prediction and is easily available in standard finite elements. In the present damage model, the damaged stiffness tensor is constructed to form a crack surface, and the energy dissipation in the damaged element is only allowed in the direction perpendicular to the crack plane. Crack surface is divided into crack lines and crack triangles based on the first introduced crack surface discretization, and the application scope of local tracking algorithm is extended from two dimension to 3D. The present tracking algorithm not only guarantees the continuity and stability of the predicted crack path by solving the topological problems but also has low computational cost, keeping the advantages of local tracking. The method does not identify the crack plane within each element, but it couples well with smeared crack method by identifying all the elements through which the crack surface passes. The high efficiency and stability of the present approach are verified by resolving several 3D benchmark problems in failure analysis.
Dynamically dimensioned search embedded with piecewise opposition-based learning for global optimization
(2019-05-26) Xu, Jianzhong; Yan, Fu; Yun, Kumchol; Ronald, Sakaya; Li, Fengshu; Guan, Jun
Dynamically dimensioned search (DDS) is a well-known optimization algorithm in the field of single solution-based heuristic global search algorithms. Its successful application in the calibration of watershed environmental parameters has attracted researcher’s extensive attention. The dynamically dimensioned search algorithm is a kind of algorithm that converges to the global optimum under the best condition or the good local optimum in the worst case. In other words, the performance of DDS is easily affected by the optimization conditions. Therefore, this algorithm has also suffered from low robustness and limited scalability. In this work, an improved version of DDS called DDS-POBL is proposed. In the DDS-POBL, two effective methods are applied to improve the performance of the DDS algorithm. Piecewise opposition-based learning is introduced to guide DDS search in the right direction, and the golden section method is used to search for more promising areas. Numerical experiments are performed on a set of 23 classic test functions, and the results represent significant improvements in the optimization performance of DDS-POBL compared to DDS. Several experimental results using different parameter values demonstrate the high solution quality, strong robustness, and scalability of the proposed DDS-POBL algorithm. A comparative performance analysis between the DDS-POBL and other powerful algorithms has been carried out by statistical methods by using the significance of the results. The results show that DDS-POBL works better than PSO, CoDA, MHDA, NaFA, and CMA-ES and gives very competitive results when compared to INMDA and EEGWO. Moreover, the parameter calibration application of the Xinanjiang model shows the effectiveness of the DDS-POBL in the real optimization problem.
Contribution of climatic variability and human activities to stream flow changes in the Haraz River basin, Northern Iran
(Journal of Hydro-environment Research, 2019-06) Pirnia, Abdollah; Darabi, Hamid; Choubin, Bahram; Omidvar, Ebrahim; Onyutha, Charles; Haghighi, Ali Torabi
In northern Iran’s Haraz River basin between 1975 and 2010, hydrological sensitivity, double mass curve, and Soil and Water Assessment Tool (SWAT) methods were applied to monitoring and analysing changes in stream flow brought on by climatic variability and human activities. Applied to analyse trends in annual and seasonal runoff over this period, the sequential MK test showed a sudden change point in stream flow in 1994. The study period was, therefore, divided into two sub-periods: 1975–1994 and 1995–2010. The SWAT model showed obvious changes in water resource components between the two periods: in comparison to the period of 1975–1994, sub-watershed-scale stream flow and soil moisture decreased during 1995–2010. Changes in evapotranspiration were negligible compared to those in stream flow and soil moisture. The hydrological sensitivity method indicated that climatic variability and human activities contributed to 29.86% and 70.14%, respectively, of changes in annual stream flow, while the SWAT model placed these contributions at 34.78% and 65.21%, respectively. The double mass curve method indicated the contribution of climatic variability to stream flow changes to be 57.5% for the wet season and 22.87% for the dry season, while human activities contributed 42.5% and 77.13%, respectively. Accordingly, in the face of climatic variability, measures should be developed and implemented to mitigate its impacts and maintain eco-environmental integrity and water supplies.
Enhancing a sustainable safe water supply for rural communities of Mabungo parish, Kisoro district
(Kyambogo University (un published work), 2019-07) Kwitegetse, Penlope
Access to safe water is still a challenge in Africa, the biggest population that suffers the challenge being from sub-Saharan African countries where Uganda is part. The major cause of limited water access is that 85% of water supply systems stop supplying water after a short while from time of implementation. The situation escalates the water crisis forcing people to use raw water from the available water bodies. This involves trekking very long distances coupled with the risk of acquiring water-borne diseases. This study focused on Mabungo parish, in Kisoro district, and investigated the factors that influence sustainable supply of water systems in the area. Data was collected from 269 respondents within Kisoro district using questionnaires. The sustainability of the potential scheme in the Mabungo parish was also tested using the participatory research method, which came up with a community based model for sustainable water supply for the communities. The results confirmed Kabiranyuma scheme to have potential for supplying Mabungo communities with safe water to the required level of sustainability. Adopting a participatory approach among communities of Mabungo, has high opportunities of contributing towards achievement of sustainable development goal 6, which aims at ensuring universal access to clean water and sanitation by 2030. The approach prepares rural communities to manage their water supply systems themselves during and after implementation. Though full involvement of communities in operating and managing a water supply is the main way to ensure proper functionality and sustainability, It is important to note that, support from Local Government, the responsible Ministry or external entities in form of finance, technical back stopping, operational infrastructure, regular supervision, among others can do a great deal in boosting their performance. Communities were encouraged to practice rain water harvesting to be used as a supplementary water supply in the study area. Keywords: Rural communities, water access, sustainability, enhancement, safe water
Investigations into the mechanical performance of Ugandan made carbon steel bars
(Kyambogo University (un published work), 2019-08) Ssempijja, Deo
Carbon steel bars are one of the most used steel products in structural constructions worldwide. Ugandan steels have been reported to have significant amounts of residual elements due to use of scrap steel in their production. Variations in carbon content have been reported in the Ugandan made reinforcing steel bars made from scrap raw material indicating a lack of chemical composition control. Therefore, to ascertain the compliance with quality standards, this study investigated the mechanical performance of Ugandan made carbon steels bars (20mm TMT ribbed bars) focusing on chemical composition, microstructure, tensile strength, and bendability. A comparison of the results with the requirements of the quality standards BS 4445: 2005 and the East African standard, EAS 412 - 1: 2005, based on ISO 6935 were used to establish the performance of the Ugandan made steel bars. Three (3) steel producing companies were considered based on their annual production capacity. In order not to identify the steel companies chosen, the companies were coded as A, B and C. A total of nine (9) steel bars of 20mm diameter were used in experiments. Three (3) bars were picked from the distributors of each of the steel producers selected. A spark emission spectrometry was used for chemical composition analysis, photo Microscopy of x500 was used for microstructure analysis and a universal tensile testing machine was used for both tensile strength and bendability tests. The carbon equivalent value (CEV) ranged between 0.363% and 0.374% for company A, 0.307% to 0.323% for company B and company C between 0.347% and 0.397% which are within acceptable range according to BS 4445: 2005 standards ranging 0.3 to 0.55%. There were variations in the microstructures of steel bars. The tensile strength (UTS) alternated between 640N/mm2 and 714N/mm2, the yield strength (YS) extended between 538N/mm2 and 600N/mm2, UTS/YS ratio was between 1.252 and 1.195 and the percentage elongation 18% to 22%. The values were all within the acceptable range according to BS 4445:2005 standards. The maximum bending force needed to bend to 900 was found to be 52235N with a maximum deflection of 74.4mm. The Steel bars exhibited bending stress with a range of 148 N/mm2 to 166 N/mm2. The general mechanical performance of the 20mm steel bar had acceptable quality standards basing on BS 4445: 2005 and the East African standard, EAS 412 - 1: 2005, based on ISO 6935 but with variations in carbon equivalent values. Key words: carbon steel bars, chemical composition, microstructures, tensile strength and bendability

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