NRU :: Browsing by Author "Ekyalimpa, Ronald"

Browsing by Author "Ekyalimpa, Ronald"

Now showing 1 - 11 of 11

Assessing willingness to pay for water during the COVID-19 crisis in Ugandan households
(Social Sciences & Humanities Open, 2021) Sempewo, Jotham Ivan; Kisaakye, Peter; Mushomi, John; Tumutungire, Martin Dahlin; Ekyalimpa, Ronald
With the emergence of COVID-19, improving hygiene through handwashing with water and detergent is a priority. This behavioural practice requires that households have access to reliable improved water. One measure that can provide an invaluable source of information to measure access to improved water supply is willingness to pay (WTP). However, little is known about WTP for water during a pandemic such as COVID-19. Data from a cross-sectional survey was used to assess potential household determinants of WTP for water during March-June 2020 in 1639 Ugandan households. The focus is on the period March-June 2020 when the government of Uganda implemented a countrywide total lockdown in a bid to curb the spread of the deadly virus. Results indicate that most households were not willing to pay for water during March-June 2020. Sex of the household head, region of residence, water source, number of times hands are washed and whether a household buys or pays for water were significant explanatory household determinants for WTP for water. The results provide a rich understanding of the household factors that determine WTP for water during a pandemic. This evidence is important in guiding government and water utilities in developing sustainable regulations and policy interventions particularly during emergencies. The findings suggest that increasing or maintaining water revenues will be a challenge in emergencies if no attention is placed to addressing the disparity in socio-economic attributes associated with households’ WTP.
A Combined Discrete-Continuous Simulation Model for Analyzing Train-Pedestrian Interactions
(IEEE., 2016) Ekyalimpa, Ronald; Werner, Michael; Hague, Stephen; AbouRizk, Simaan
Computer simulation has defined itself as a reliable method for the analysis of stochastic and dynamic complex systems in both academic and practical applications. This is largely attributed to the advent and evolution of several simulation taxonomies, such as, Discrete Event Simulation, Continuous Simulation, System Dynamics, Agent-Based Modeling, and hybrid approaches, e.g., combined discrete-continuous simulation, etc. Each of these simulation methods works best for certain types of problems. In this paper, a discrete-continuous simulation approach is described for studying train and pedestrian traffic interactions for purposes of decision support. A practical operations problem related to commodity train operation within two small towns in Alberta, Canada, is then used to demonstrate the implementation of the approach within the Simphony.NET simulation system. Simulation results generated are presented.
Customized k-Nearest Neighbourhood Analysis in the Management of Adolescent Idiopathic Scoliosis using 3D Markerless Asymmetry Analysis
(Computer Methods in Biomechanics and Biomedical Engineering, 2019) Ghaneei, Maliheh; Ekyalimpa, Ronald; Westover, Lindsey; Parent, Eric C.; Adeeb, Samer
Adolescent Idiopathic Scoliosis (AIS) is a 3D spinal deformity characterized by curvature and rotation of the spine. Markerless surface topography (ST) analysis has been proposed for diagnosing and monitoring AIS to reduce the X-ray radiation exposure to patients. This method captures scans of the cosmetic deformity of the torso using visible, radiation-free light. The asymmetry analysis of the torso, represented as a deviation contour map with deviation patches outlining the areas of cosmetic asymmetries, has previously been shown to predict the severity and progression of the condition in comparison with radiographs, by using classification trees. While the classification results were promising, it was reported that some mild curves were erroneously diagnosed. Furthermore, this approach is highly sensitive to threshold values selected in the decision trees. Therefore, this study aims to define a custom Neighbourhood Classifier algorithm for AIS classification to improve the accuracy, sensitivity, and specificity of predicting curve severity and curve progression in AIS. Curve severity was predicted with 80% accuracy (sensitivity = 81%; specificity = 79%) for thoracic-thoracolumbar curves and 72% (sensitivity = 93%; specificity = 53%) for lumbar curves. This represents an improvement over the previous method with curve severity accuracies of 77% and 63% for thoracic-thoracolumbar and lumbar curves, respectively. Additionally, curve progression was predicted with 93% accuracy (sensitivity = 83%; specificity = 95%) representing a substantial improvement over the previous method with an accuracy of 59%. The current method has shown the potential to further reduce radiation exposure for AIS patients by avoiding X-rays for mild and non-progressive curves identified using ST analysis.
Effective Strategies for Simulating One-of-a-Kind Construction Projects
(IEEE., 2012) Ekyalimpa, Ronald; Farrar, Jack
Most construction projects are unique with respect to product features and their delivery process. Consequently, customized techniques for analyzing and designing these projects become inevitable. The authors propose use of Special Purpose Simulation (SPS) modeling techniques for such problems and discuss Simphony.Net, a discrete event simulation environment, utilities that support such developments. Past studies successfully implemented using SPS modeling are also discussed. Although SPS modeling approaches can be developed faster and are easier for practitioners to use, they are limited to the domain they model. General Purpose Simulation (GPS) is proposed as one way to overcome this limitation. This paper discusses the systematic steps to developing Simphony SPS tools, followed by a demonstration of GPS use in validation of such templates. A case study of a road construction project modeled using Surface Works Road Construction SPS is presented and validated using a Simphony GPS template, as proof of concept.
Emulation of the Central Limit Theorem Using a Monte-Carlo Based Approach
(Mathematical Theory and Modeling, 2020) Ekyalimpa, Ronald
The majority of simulation experiments fulfill the central limit theorem particularly those that are stochastic and warrant the execution of multiple iterations during the process of their experiment execution. This class of simulation models can benefit from the existence of this theorem by utilizing it as a verification approach that certifies the accuracy in which the simulation experiment has been carried out. This paper formalizes this process and proposes a framework for achieving this given that thus far, the simulation community has not put forward a standard way for doing this. The systematic behaviors of freshmen at a University (particularly related to lectures), were abstracted and studied such that the cycle length for the time that a freshman commits daily towards their lectures was simulated using a Monte-Carlo based approach. The simulation of the academic behavior of freshmen was set up in a fashion that was consistent with the proposed framework so that it was possible to showcase the strategies in which the central limit theorem can be utilized in the verification of a simulation experiment.
Exposure Condition Survey and Measurement of Defects in Compressed Stabilized Earth Block Structures in Uganda
(Journal of Environment and Earth Science, 2017) Kerali, Anthony G.; Ekyalimpa, Ronald
Inadequate provision of shelter remains a global challenge. The high cost of building materials is responsible for this situation. The compressed and stabilised earth block (CSEB) has been promoted as a low cost material. While its other properties are well understood, the behaviour of the material over time has not been properly researched. The principal objective of this research was to investigate their in-service exposure and measure defects in a humid tropical environment. Such areas are characterised by extremes of weather. The soils are also varied. The paper examines the effects of natural exposure conditions on the deterioration of CSEBs. The methodology involved literature review, visual inspection, exposure condition survey, and measurement of defects. It was confirmed that premature deterioration was widespread in exposed structures, with visible defects. The paper recommends an urgent need for improvement in the production and use of CSEBs through dissemination of location specific appropriate specifications, standards and codes. It further proposes the need for improved protective measures in the humid tropics. Additional improvement can be achieved via better intergranular bonding, reduction in voids, lowered water absorption, and protective designs and specifications. Hence, future challenges can be prevented and the effects of identified deterioration agents minimised
Fuzzy Cognitive Maps as a Tool for Modeling Construction Labor Productivity
(IEEE, 2015) Ahn, Seungjun; Chettupuzha, A. J. Antony; Ekyalimpa, Ronald; Hague, Stephen; AbouRizk, Simaan M.; Stylios, Chrysostomos D.
Labor productivity is a fundamental building block of planning and controlling in construction, and therefore, predicting labor productivity levels for a given condition is very important in construction management. However, predicting labor productivity is extremely difficult due to a large number of factors that can affect productivity in perplexing ways. Another obstacle to predicting labor productivity is the qualitative nature and subjectivity of productivity factors. To address these issues, a soft computing technique called Fuzzy Cognitive Maps (FCMs) is proposed as a tool to model the complex inter-relationships between productivity factors based on expert knowledge, and for assessing the impact of the productivity factors on labor productivity. In this paper, the methodology for creating and using FCMs for this purpose is introduced, and then an exercise is presented for demonstration purposes. Additionally, issues identified from this exercise are described, and the way that FCMs can be practically used in the field for predicting labor productivity is also discussed in the paper.
The Impact of COVID-19 on Households’ Water Use in Uganda
(Water Supply, 2021) Sempewo, Jotham Ivan; Mushomi, John; Tumutungire, Martin Dahlin; Ekyalimpa, Ronald; Kisaakye, Peter
The unprecedented outbreak of COVID-19 necessitated the promotion of better hygiene practices to curb the spread of the virus. Better hygiene requires that households have a stable supply of water. However, little is known about the predictors of changes in water use in emergency situations such as COVID-19 in Uganda. This study uses data from a cross-sectional survey to examine the changes in the quantities of water used by 1,639 Ugandan households due to COVID-19. This article also explores the factors that are associated with changes in water use. The month March 2020 is used in this study as a cut-off because this is the month in which the government implemented a lockdown to curb the spread of the virus. Results indicate that most households had an increase in the quantity of water used after March 2020 when compared with the period before March 2020. Household characteristics that were associated with a change in the quantity of water used were age, sex, education, main occupation of household head, household size and region of residence. The results can be used to inform the prediction and demand modelling of household water use for improved water interventions for equitable water supply during emergencies.
A Prototype for Simulating the Kinematics of Crane Rigging Oscillatory Motion using Simphony.Net
(IEEE., 2016) Ekyalimpa, Ronald; Chiteri, Martin Akolo; AbouRizk, Simaan
Crane hoisting operations represent a significant portion of the work scope on construction sites, especially those that have adopted a modularized approach to construction. Creating metrics that can be used in the automation of these processes can result in higher jobsite efficiencies from a safety and productivity perspective. This study created a virtual simulation environment prototype that can be experimented with to generate the required metrics for crane hoisting automation. The equation of motion for this oscillatory motion was first defined. Thereafter numeric solutions to this equation were explored from a continuous simulation perspective using Simphony.NET. Then prototyping of simple pendulum motion was implemented using the continuous simulation services in Simphony.NET and verification done using Mathematica.
Simulation of Mobile Falsework Utilization Methods in Bridge Construction
(IEEE., 2012) Liu, He-Xu; Siu, Ming-Fung Francis; Ekyalimpa, Ronald; Lu, Ming; AbouRizk, Simaan
Scaffolds and shoring systems are generally referred to as the falsework in bridge construction, serving as temporary structures to support bridge span construction. The falsework cost usually accounts for 50-70% of the total project concrete budget. Falsework installation and advancing methods can greatly impact the completion time and actual cost. Thus, simulation can be instrumental in planning bridge construction operations and analyzing various options by evaluating postulated “what-if” scenarios. This study uses a previously constructed bridge in Sweden as a case study to test three feasible construction sequence alternatives. One of these alternatives was implemented on the actual construction of this bridge. Modeling was performed in Simphony, which captures the unique construction sequence requirements and constraints, resulting in project durations for each alternative. Results from simulation experiments were corroborated by the construction engineer who had worked on the bridge project in terms of the advantages that each alternative method possesses.
Updating Geological Conditions using Bayes Theorem and Markov Chain
(IEEE., 2015) Zhang, Limao; Ekyalimpa, Ronald; Hague, Stephen; Werner, Michael; AbouRizk, Simaan
Due to cost constraints, geological conditions are investigated using boreholes. However, this means conditions are never known exactly, particularly for deep and long tunnels, because uncertainties exist between neighboring boreholes. Simulation can deal with underlying uncertainty, and offers benefits to project planners in the development of better alternatives and optimization. This research developed a simulation model using Bayes theorem and Markov chain, aiming to continuously update geological conditions of one-meter sections for tunnel construction, given the geological condition of the previous one-meter section is observed as construction progresses. An actual tunneling project is used as a case study to demonstrate the applicability of the developed methodology. The impacts are analyzed and discussed in detail. The simulation results show that continuous updates during construction can significantly improve prediction of project performance by eliminating uncertainty in the original assumption. The model can be expanded to predict results of future geologic exploration programs.

Browsing by Author "Ekyalimpa, Ronald"

Results Per Page

Sort Options