Engineering and Technology

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Application of a Class of Preconditioners to Large Scale Linear Programming Problems
(Springer, 1999) Baryamureeba, Venansius; Steihaug, Trond; Zhang, Yin
In most interior point methods for linear programming, a sequence of weighted linear least squares problems are solved, where the only changes from one iteration to the next are the weights and the right hand side. The weighted least squares problems are usually solved as weighted normal equations by the direct method of Cholesky factorization. In this paper, we consider solving the weighted normal equations by a preconditioned conjugate gradient method at every other iteration. We use a class of preconditioners based on a low rank correction to a Cholesky factorization obtained from the previous iteration. Numerical results show that when properly implemented, the approach of combining direct and iterative methods is promising
Cloud RAN and MEC: A Perfect Pairing
(ETSI MEC, 2018) Reznik, Alex; Murillo, Luis Miguel Contreras; Fontes, Francisco; Turyagyenda, Charles; Wehner, Christof; Zheng, Zhou
CRAN and MEC are highly complementary technologies. Collocating these helps make the economics of each of them significantly more attractive. Collocating CRAN and MEC also helps an MNO to support (and generate revenue from) some of the key 5G applications that it would not be able to support otherwise. However, to realize these advantages, mobile operators have to overcome challenges associated with co location, as well as maximize the return that can be made from MEC. We identify and discuss challenges in the management, security, networking and regulatory domains. We argue that these issues are surmountable and the industry is well-positioned to deploy this potentially revolutionary new technology. Moreover collocation can also enable MEC services (e.g. the ETSI defined Radio Network Information API, Location API, UE Identity API and Bandwidth Management API) to exploit CRAN and enable MEC applications to exploit CRAN information. Mobile operators could, for example, resolve the management complexities associated with multiple IaaS stacks, while monetizing services like RNIS, which are unique to MEC edge clouds.
A Comprehensive Review on 2D and 3D Models of Vertical Ground Heat Exchangers
(Renewable and sustainable energy reviews, 2018) Cui, Yuanlong; Zhu, Jie; Twaha, Ssennoga; Riffat, Saffa
The ground source heat pumps (GSHPs) have been extensively applied to commercial and residential buildings owing to their high-energy efficiencies and low running costs. The key component of the GSHP is a ground heat exchanger (GHE). The state-of-the-art two-dimensional (2D) and three-dimensional (3D) heat transfer models for borehole heat exchanger (BHE) and energy pile (EP) systems are reviewed in this paper. The physical procedures of heat transfer and the derivation of energy conservation within different channels of BHE (e.g., U-, W-, helical-shaped or coaxial-shaped) are summarized, in addition to the primary merits and demerits of each model. The main influencing factors on 2D and 3D model solutions including axial heat transfer, friction heat, spacing shack, thermal resistance, thermal short-circuiting between the inlet-pipe and outlet-pipe, are analysed and compared. Furthermore, various applications of these 2D and 3D models are elaborated. Finally, the recommendations, standpoints and potential future research on BHE heat transfer model are highlighted. It is believed that the work presented will contribute to the record of information and experiences necessary to develop BHEs for GSHP systems.
Ethanol for an Agriculture-based Developing Economy: A computable general equilibrium assessment for Uganda
(Energy for Sustainable Development, 2020) Nakamya, Miria; Romstad, Eirik
This study uses a static computable general equilibrium (CGE) model to examine the potential economic impacts of ethanol production in Uganda. We introduce an ethanol sector in the 2016/17 Uganda's social accounting matrix (SAM) using maize, cassava, sugarcane, and molasses as feedstocks. Furthermore, we evaluate the suitability of each feedstock. By simulating a 10% blending mandate, we find that factor employment and total output would increase, with a sluggish rise in commodity prices. Real GDP would grow moderately, and household income increase, mostly for the rural households. Household welfare would decline because of a counter-financing tax on gasoline. A reduction in gasoline imports is likely to improve the trade balance, and despite the ensuing decline in import tax revenues, government income would still rise. Our results are suggestive of ethanol production as a potential pro-poor project for Uganda. Both sugarcane and maize are more growth-enhancing compared to cassava. The use of only molasses from the sugar industry may result in negative impacts since it is already an input in other activities. We also observe that using an average of multiple feedstocks would be more sustainable. Moreover, it would allow a more balanced growth while reducing upward price pressures.
Exploring the Implementation of Blended Learning in a Developing Country: A Case Study of Uganda
(Fountain Publishers, 2008) Ayoo, Philip O.; Lubega, Jude T.
This paper explores on how the blended learning method has been implemented in the developing country such as Uganda. Many higher education institutions in Uganda have acquired a new form of learning using technology that they combine with the traditional learning methods. Implementation of this form of learning using technology has been challenged by several factors. Many of the challenges are attributed to the conditions that exist in a developing world such as lack of appropriate technology. In spite of the several challenges blended learning has been implemented in relation to the existing internal procedures to suit the developing world context. The study strategy aimed to identify if the procedures initiated for implementing blended learning in the developing world were suitable. A case study approach was adopted in order to inspect these implementation procedures used within a higher education setting. The results from the study indicate that despite the lack of the appropriate technologies, infrastructure, pedagogical knowledge, quality assurance procedures and capital to invest, hybrid policies/frameworks are implemented. For this reason, a lot of higher education institutions are falling short of the implementation policies adopted. Therefore the paper stipulates that it is not simply adopting what the developed world has done but designing what suits the contextual setting that the particular country posses.
Fully Coupled Surface–Subsurface Hydrological Modeling to Optimize Ancient Water Harvesting Techniques
(Handbook ofWater Harvesting and Conservation: Case Studies and Application Examples, 2021) Cornelis, Wim M.; Verbist, Koen; Araya, Tesfay; Opolot, Emmanuel; Wildemeersch, Jasmien C.J.; Al-Barri, Bashar
Worldwide, but particularly in drylands, water scarcity has become a major limitation to crop production and to delivering ecosystemservices in general. Likewise, in many regions rainfall is becoming more erratic, with later and shorter rainy seasons, more and longer dry spells, and fewer rainy days (Sillmann et al. 2013), even in cases when total rainfall is increasing (Wu et al. 2013; Greve et al. 2014). This might be linked to anthropogenic climate change (Rockström and Falkenmark 2015). It results in a higher frequency of particularly agricultural droughts – shortage of available water for plant growth – which generally occur more often than meteorological droughts, i.e. shortage of precipitation (Wani et al. 2009). In order to improve food and water security, water harvesting in its broadest sense should be an entry-point activity to enhance crop production through sustainable/ ecological intensification. On a larger scale it contributes to regreening of the landscape, through crops, grasses, shrubs, or trees, hence rendering ecosystem services for society (Stroosnijder 2009). In a broad sense,water harvesting refers to retaining rainwater by in situ and ex situ practices (Dile et al. 2013; Cornelis 2014). In situ practices capture and store water where it falls, whereas ex situ practices collect water from a larger area and convey it to fields for immediate use or to storage systems for later use. Various examples are given elsewhere within this book.
Generalized Association Rule Mining Using Genetic Algorithms
(Fountain Publishers, 2008) Wakabi-Waiswa, Peter P.; Baryamureeba, Venansius; Sarukesi, K.
We formulate a general Association rule mining model for extracting useful information from very large databases. An interactive Association rule mining system is designed using a combination of genetic algorithms and a modified a-priori based algorithm. The association rule mining problem is modeled as a multi-objective combinatorial problem which is solved using genetic algorithms. The combination of genetic algorithms with a-priori query optimization make association rule mining yield fast results. In this paper we use the same combination to extend it to a much more general context allowing efficient mining of very large databases for many different kinds of patterns. Given a large database of transactions, where each transaction consists of a set of items, and a taxonomy (is-a hierarchy) on the items, we find associations between items at any level of the taxonomy. We show how the idea can be used either in a general purpose mining system or in a next generation of conventional query optimizers.
A Generic E-Learning Framework: A Case Study Faculty of Computing and Information Technology (CIT) Makerere University
(Fountain Publishers, 2008) Lubega, Jude T.; Ssozi Mugarura, Fiona
Advancement in Information Technology (IT) has led to better facilities and services for learning within educational organizations. Many higher educational institutions of learning have adopted technology in their learning methods in order to enhance the traditional learning method and to offer distance/purely online learning. This enhancement is in the form of management, administration, facilitation, delivery and support of the modules/courses delivered using the electronic media. Makerere University’s strategy for ICT implementation strives for use of technology during learning hence its adoption by several faculties within their teaching methods. Makerere University Faculty of Computing and Information Technology (CIT) developed a generic e-learning framework to guide it in implementing an effective blended learning process (traditional classroom and e-learning). CIT’s goal is to implement a complete e-learning program gradually by first initiating a blended learning approach. The lessons learnt from the blended learning approach would enhance implementation of a complete e-learning program. This paper describes the generic e-learning framework developed by CIT in the implementation of the blended learning approach. The framework constituents several components that are derived from the organizational environmental factors. These components include organizational policy, funding, stakeholders, services and infrastructure. The components’ constituting factors are inter networked to allow a specific learning method (blended, purely online or distance learning) to be implemented. The framework in operation is illustrated by a typical case study of blended learning in CIT.
Geometrical Spatial Data Integration in Geo-Information Management
(Fountain Publishers, 2007) Wadembere, Ismail; Ogao, Patrick J.
One of the reasons that Individual users and organizations use GIS, is to exchange geospatial data as a means to location based decision-making. A considerable amount of preprocessing has to be done, before and after the data has been integrated. Within this decade, we are seeing developments in technologies which are creating services which need geospatial data comparison and integration (Najar et al., 2006). This is so evident in: Google Earth; Microsoft’s MapPoint.Net; O’Reilly’s Where 2.0; Intergraph’s reorganization around “SIM”; Oracle Locator and Spatial; ESRI’s ArcGIS 9.x; US Census’ MAF/TIGER integration; new platforms, new vendors, new users and the many conferences on mobile commerce and locationbased services (Batty, 2004, Alperin, 2005) and varying application (Busgeeth and Rivett, 2004). These developments and changes are so diverse that they don’t even seem related, but they are (Sonnen, 2005); that is, they take advantage of the vast geo-information available, which reflect the increased importance of location in information systems and services (Strader et al., 2004).
ICT as an Engine for Uganda’s Economic Growth: The Role of and Opportunities for Makerere University
(Fountain Publishers Kampala, 2007) Baryamureeba, Venansius
The use of Information and Communications Technologies (ICT) to improve how goods are produced and services are delivered is a feature of everyday life in developed countries. If ICT is used appropriately, it has the potential to vastly improve productivity. Thus the issue for developing and least developed countries is how best to use ICT to achieve development objectives, given the operating constraints in these countries. The constraints are mainly lack of infrastructure and human capacity. It is now a known fact that ICT infrastructure readiness without adequate skilled ICT human capacity cannot lead to economic growth. In this paper we discuss the role of Makerere University and suggest opportunities for Makerere University in this area of ICT led –economic growth of Uganda.
ICT-enabled Services: A Critical Analysis of the Opportunities and Challenges in Uganda
(Fountain Publishers, 2008) Baryamureeba, Venansius
Information and Communications Technologies (ICTs), broadly defined, facilitate by electronic means the creation, storage, management and dissemination of information. ICT is both a vehicle for communication and a means of processing information. ICTs are part of the economic infrastructure that supports global production, trade, investment and capital flows. ICTs are means by which individuals, institutions and organizations network, undertake activities, and participate in the development process at local, national and global levels. Specifically the ICT industry is the main driver of the economies of countries like India and China. In Europe, according to the EU Commission’s annual progress report on i2010 [EU Annual report 2007], ICT drives 50% of EU growth. Denmark, The Netherlands, Finland, Sweden, The UK and Belgium -- all have higher broadband penetration rates than the USA and Japan. Technology is fuelling innovation and productivity, and there are signs of fundamental change in markets and user behavior, as countries move towards a knowledge-based economy.
The Impact of Equal Weighting of Low and High-Confidence Observations on Robust Linear Regression Computations
(BIT Numerical Mathematics, 2001) Baryamureeba, Venansius
Equal weighting of low- and high-confidence observations occurs for Huber, Talwar, and Barya weighting functions when Newton’s method is used to solve robust linear regression problems. This leads to easy updates and/or downdates of existing matrix factorizations or easy computation of coefficient matrices in linear systems from previous ones. Thus Newton’s method based on these functions has been shown to be computationally cheap. In this paper we show that a combination of Newton’s method and an iterative method is a promising approach for solving robust linear regression problems. We show that Newton’s method based on the Talwar function is an active set method. Further we show that it is possible to obtain improved estimates of the solution vector by combining a line search method like Newton’s method with an active set method.
Improving reliability and functional sustainability of groundwater handpumps by coating the rubber piston seals with diamond-like carbon
(Honor, 2015) Lubwama, Michael; Corcoran, Brian; Kirabira, John Baptist; Sebbit, Adam; Sayers, Kimmitt
In many rural communities, handpumps are essential in order to provide access to safe drinking water from groundwater sources. The functional sustainability of handpumps is poor, however, and most maintenance issues in handpumps are caused by wear of the nitrile rubber piston seals. This study identified handpump problems faced by a rural community in southern Uganda, specifically related to wear of piston seals. We investigated a novel surface-engineering approach to improve the wear resistance of piston seals by depositing diamond-like carbon (DLC), and silicon (Si) doped DLC onto the seals. Wear mechanisms for the coated seals were determined using a piston seal wear test rig. Tests were undertaken with clean normal water, and water seeded with sand particles. Wear mechanisms identified included adhesion, abrasion, and fatigue. For the DLC and Si-DLC coated piston seals the dominant wear mechanism was abrasion, with minimal fatigue wear. Adhesive wear on the coated piston seals is explained by the generation and transfer of a tribo-layer, which increases wear resistance and functional sustainability of the piston seal. Wear resistant seals could significantly reduce the maintenance costs of existing handpump designs, and improve their functional sustainability.
Information Communication Technologies Acceptance and Use Among University Communities in Uganda: A Model for Hybrid Library Services End-Users
(Fountain Publishers, 2008) Tibenderana, Prisca K. G.; Ogao, Patrick J.
Since their inception during the first century, library institutions have used manual operations to provide services to patrons. Information seekers in these libraries spent a lot of time perusing through card catalogues and searching rows of stacks for material that may have been checked out by someone else. The tradition tool and techniques were inadequate and time consuming. The introduction of the new technologies has changed this concept and what we have now are hybrid libraries based on computer networks and physical facilities. This investigation is an effort to examine alternative measures of intention in revalidating and expanding (Venkatesh et al. 2003) UTAUT model in the context of hybrid library services using university communities in a less developed country, Uganda.
Measuring Computing Research Excellence and Vitality
(Fountain Publishers, 2006) Ddembe, Williams; Baryamureeba, Venansius
Measuring computing excellence and vitality has become an important approach to understanding sustainable information and communication technology (ICT) for societal transformation and development around the world. In particular, developing countries are being encouraged to invest in ICT infrastructure so that they might experience the expected future social and economic benefits. This book is aimed at developing an integrated framework for measuring sustainable research excellence and vitality in computer science, in Uganda and the immediate African regions. Improving the sustainability and vitality of research capacity has become an important problem in information communication and technology (ICT), and more specifically computing research in the higher education setting for both developed and developing countries. There is little research on the factors that influence research excellence and vitality in computer science.
A Methodology for Feature Selection in Named Entity Recognition
(Fountain Publishers, 2007) Kitoogo, Fredrick Edward; Baryamureeba, Venansius
In this paper a methodology for feature selection in named entity recognition is proposed. Unlike traditional named entity recognition approaches which mainly consider accuracy improvement as the sole objective, the innovation here is manifested in the use of a multiobjective genetic algorithm which is employed for feature selection basing on various aspects including error rate reduction and time taken for evaluation, and also demonstrating the use of Pareto optimization. The proposed method is evaluated in the context of named entity recognition, using three different data sets and a K-nearest Neighbour machine learning algorithm. Comprehensive experiments demonstrate the feasibility of the methodology.
On Efficient Distribution of Data in Multicast Networks: QoS in Scalable Networks
(Springer, 2005) Lowu, Francis; Baryamureeba, Venansius
Multimedia applications or real-time applications such as audio and video on demand, teleconferencing and whiteboard sharing require Quality of Service (QoS) guarantee assurance. QoS constraints, namely required bandwidth, end-to-end delay and delay jitter are the major parameters that need to be satisfied in order to have quality assurance in a dynamic multicast network. In this paper we investigate the effect of the QoS constraints on multicast network applications and services during the processes of routing. Lastly, we propose linear routing tree algorithms for required bandwidth, end-to-end delay and delay jitter.
On the Convergence of an Inexact Primal-Dual Interior Point Method for Linear Programming
(Springer, 2005) Baryamureeba, Venansius; Steihaug, Trond
The inexact primal-dual interior point method which is discussed in this paper chooses a new iterate along an approximation to the Newton direction. The method is the Kojima, Megiddo, andMizuno globally convergent infeasible interior point algorithm. The inexact variation is shown to have the same convergence properties accepting a residue in both the primal and dual Newton step equation also for feasible iterates.
Properties of Preconditioners for Robust Linear Regression
(Fountain Publishers, 2000) Baryamureeba, V.; Steihaug, T.
In this paper, we consider solving the robust linear regression problem y = Ax + ∈ by an inexact Newton method and an iteratively reweighted least squares method. We show that each of these methods can be combined with the preconditioned conjugate gradient least square algorithm to solve large, sparse systems of linear equations efficiently. We consider the constant preconditioner ATA and preconditioners based on low-rank updates and downdates of existing matrix factorizations. Numerical results are given to demonstrate the effectiveness of these preconditioners.
A Review of Termination Rules of an Inexact Primal-Dual Interior Point Method for Linear Programming Problems
(Investigación Operacional, 2018) Baryamureeba, Venansius; Steihaug, Trond; El Ghami, Mohamed
In this paper we apply the Inexact Newton theory on the perturbed KKT-conditions that are derived from the Karush-Kuhn-Tucker optimality conditions for the standard linear optimization problem. We discuss different formulations and accuracy requirements for the linear systems and show global convergence properties of the method.

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