Abstract:Following the increasing global awareness of the dangers posed by the present state of climate change, many countries such as Uganda have adapted long-term plans for a transition to decarbonised economies. A major strategy for decarbonisation is to replace fossil fuels with renewable energy (RE) sources as the fundamental energy source. Uganda has substantial RE resources for the provision of energy services and production, yet these resources remain untapped. It is therefore crucial that the use of these abundant resources should be heightened. This paper examines and discusses the potential and current RE utilization and development in Uganda from the perspective of sustainable development. The status of the different RE resources and their application/utilization, including details of existing projects in the country, are carefully explored and discussed. The possible drivers for a huge advancement of RE applications and development in Uganda are also discussed before elucidating the major barriers and challenges faced by the energy sector as regards RE. Measures and policies required to facilitate the utilization of RE in Uganda are proposed. These evidence-based policies could guide the delivery of affordable and sustainable energy solutions for all by 2030 in Uganda.

This paper presents the results of experimental and theoretical/computational micro-wrinkles and buckling on the surfaces of stretchable poly-dimethylsiloxane (PDMS) coated with nano-scale Gold (Au) layers. The wrinkles and buckles are formed by the unloading of pre-stretched PDMS/ Au structure after the evaporation of nano-scale Au layers. They are then characterized using atomic force microscopy and scanning electron microscopy. The critical stresses required for wrinkling and buckling are analyzed using analytical models. The possible interfacial cracking that can occur along with film buckling is also studied using finite element simulations of the interfacial crack growth. The implications of the results are discussed for potential applications of microwrinkles and micro-buckles in stretchable electronic structures and biomedical devices.

This paper presents the results of an experimental study of the adhesion between bi-material pairs that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, organic bulk heterojunction solar cells, and hybrid organic/inorganic solar cells on flexible substrates. Adhesion between the possible bi-material pairs is measured using force microscopy (AFM) techniques. These include: interfaces that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, bulk heterojunction solar cells, and hybrid combinations of titanium dioxide (TiO 2) and poly(3-hexylthiophene). The results of AFM measurements are incorporated into the Derjaguin-Muller-Toporov model for the determination of adhesion energies. The implications of the results are then discussed for the design of robust organic and hybrid organic/inorganic electronic devices. V

Over the past decades, construction delays have been perceived as a global challenge that hinders the time delivery, budget, and quality of construction projects. It is the most common, expensive, and risky problem associated with both private and public construction projects. Within this context, the aim of this study is to investigate the significant factors that influence delays in construction projects in Hargeisa, using the road and building projects as a baseline. Through a questionnaire survey with 51 critical delay factors that are categorized into seven major groups, data were collected from 51 construction stakeholders selected based on simple random sampling from the different construction companies. Feedback from the respondents was analyzed using Relative Importance Index (RII) for ranking purposes. Results showed that delay in honoring payment progressively, underestimation or overestimation of the project cost, and delay in the approval of major changes in the work scope were ranked as the three major causes of delays in construction projects in Hargeisa. The implications of these results are vital to future projects as they clearly demonstrate how less attention is given to the application of project management tools such as robust cost, scope and risk management in construction projects. As such, construction stakeholders are recommended to make efforts to use the appropriate project management practices needed to manage the 16 identified critical delay factors, when executing future construction projects. Although, the current study focused on Somaliland construction projects, it expands and improves the understanding of delay factors in the global context, and as such can be applied to other countries and future studies.

This paper presents the results of an experimental study of the effects of surface texture on the optical and light trapping properties of silicon wafers. Surface texture is controlled by anisotropic etching with potassium hydroxide (KOH) and isopropyl alcohol (IPA) solutions. The anisotropic etching of (001) crystalline silicon wafers is shown to result in the formation of {111} pyramidal facets on the surfaces of the wafers. A combination of profilometry, optical microscopy, scanning electron microscopy, and atomic force microscopy is used to study the effects of KOH/IPA etching on the morphology and roughness of the textured surfaces. The results show that IPA concentration has the strongest effect on the surface roughness of (001)-single crystal crystals at temperatures up to 80 °C. Above this value, evidence of temperature-induced cracking was revealed on the silicon substrate. The best volume concentration ratio of KOH:IPA is also found to be 2:4. The implications of the study are discussed for the design of light trapping in silicon solar cells.

This paper presents the results of a study on the reliability and performance of the solar-powered street lighting systems installed at the African University of Science and Technology (AUST) in Nigeria, a hot and humid environment. The technical performance of the systems was studied using the following performance indicators: system energy yield, capture loss, as well as the system performance ratio while the reliability of the systems was examined using a model developed from the findings from the maintenance and fault diagnosis of the systems. The model was used to predict the total failure and survival probability of the systems using the Weibull distribution. The performance evaluation during the monitored period (February 2012 to January 2015) indicated that the performance ratios of the systems vary from 70% to 89% and the energy yields of the systems ranging from 2.87 h/day to 5.57 h/day. The results from the reliability analysis also showed that when the stress concentration factor around the notch between the cable terminals in the charge controller increases, the charge controller will become overheated, which in turn affected other components of the systems. The implications of this study are also discussed for the design and development of future solar-powered street lighting systems.

This paper presents the results of an analytical and computational study of the contacts and interfacial fracture associated with the cold welding of Organic Light Emitting diodes (OLEDs). The effects of impurities (within the possible interfaces) are explored for contacts and interfacial fracture between layers that are relevant to model OLEDs. The models are used to study the effects of adhesion, pressure, thin film layer thickness and dust particle modulus (between the contacting surfaces) on contact profiles around impurities between cold-welded thin films. The lift-off stage of thin films (during cold welding) is then modeled as an interfacial fracture process. A combination of adhesion and interfacial fracture theories is used to provide new insights for the design of improved contact and interfacial separation during cold welding. The implications of the results are discussed for the design and fabrication of cold welded OLED structures.

In this study, we reported a low-temperature, one-step solution process to fabricate perovskite solar cells using dehydrated lead acetate as the lead source. These perovskite films were aged at 200 s before thermal annealing at 90 °C for 5 min. Uniform perovskite films with lesser pinholes were obtained by this technique. The inverted planar (n-i-p) perovskite solar cell device resulted in a power conversion efficiency of 13%. A substantial finding was that the devices demonstrated high reproducibility. We also investigated the effect of annealing temperature on the optical and structural properties of the films and on the photovoltaic performances of the fabricated solar cell devices. For the aforementioned, a low-temperature, onestep solution process, the optimal temperature was achieved at 90 °C.