University of Khartoum Engineering Journal
The University of Khartoum Engineering Journal (UofKEJ) is an open access journal published in English and/or Arabic by the Faculty of Engineering, University of Khartoum.
University of Khartoum Faculty of Engineering
Parametric Study on the Adsorption of Gold onto Activated Carbon from Gold Cyanide Solutions
The adsorption process using activated carbon is widely adopted in the gold extraction industry. This study investigates the effect of the adsorbent concentration, initial gold concentration, pH, contact time, agitation speed and the total dissolved solids on the adsorption of gold onto activated carbon from gold cyanide solutions. Adsorption was found to be strongly affected by the aforementioned factors, with the exception of the initial gold concentration and total dissolved solids (TDS). The optimum values obtained were 10 g/L (adsorbent concentration), pH 10, and 70 rpm (agitation speed), achieving more than 90% adsorption in less than 40 minutes at ambient temperature and pressure.
الحقوق الفكرية (c) 2026 https://creativecommons.org/licenses/by-nc-nd/4.0
Spreading Factor-Dependent Carrier Frequency Offset Tolerance in LoRa: Empirical Characterisation and Oscillator Selection for Adaptive Data Rate Networks
Carrier frequency offset (CFO) tolerance in Long-Range (LoRa) modulation decreases with increasing spreading factor because longer symbol durations accumulate greater phase rotation per unit frequency error. This paper presents a systematic empirical characterization of CFO tolerance across the LoRa spreading factor range under controlled high-margin indoor conditions using a software-defined radio receiver. Five spreading factors (SF7–SF10 and SF12) are directly measured; SF11 is estimated by log-linear interpolation owing to a software decoder limitation. Measured tolerance ranges from more than 20 kHz at SF7 to 0.5 kHz at SF12—a 40-fold variation—and exhibits two distinct behavioral regimes: a tracking-limited plateau at SF7–SF8 and a coherence-failure regime at SF9–SF12 described by an exponential decay model. Measured tolerances exceed Semtech theoretical predictions by factors of 66–189, attributed to receiver-side implementation techniques including fractional frequency estimation and soft-decision decoding. These measured margins are then compared with the frequency drift of standard ±10 ppm crystal oscillators (8.68 kHz at 868 MHz) to identify a graduated vulnerability threshold: SF7–SF9 operates with adequate margin, SF10 lies in a marginal zone where forward error correction compensated for physical-layer errors under the controlled conditions of this study, and SF11–SF12 operates below the commodity oscillator drift limit. Because Adaptive Data Rate (ADR) algorithms may increase the spreading factor dynamically, oscillator adequacy at low spreading factors does not guarantee adequacy across the full ADR range. An evidence-based oscillator selection framework is derived from these results. SF11 CFO tolerance is reported as an estimate obtained by log-linear interpolation, clearly labelled throughout, owing to a decoder limitation of the software demodulator used.
Production of Activated Carbon from Baobab Fruit (Adansonia digitata L.) Shell
Activated carbon (AC) is an amorphous form of carbon with a highly developed internal pore structure and large surface area, making it an excellent adsorbent. This study investigates the optimal conditions for producing activated carbon from baobab fruit shells, an abundant agricultural waste in Sudan, by varying carbonization temperature, particle size, time, and activation agent. The highest yield (29.653%) was obtained for particle sizes of 6–14 mm at 500°C for 2 hours. HCl was the most effective activation agent (1 M, 60 min exposure), achieving 98.6% methylene blue adsorption. This work highlights the potential of baobab shells as a low-cost and sustainable precursor for activated carbon production, reducing waste and import dependency.
Assessing Sudan’s Capabilities for IIoT-Based Power Systems
Sudan’s power sector stands at a critical point. The country faces serious challenges such as aging infrastructure, frequent power outages, and very high transmission and distribution losses compared to other countries in the region. At the same time, Sudan has a foundation for improvement, including significant hydro and thermal power capacity and a telecommunications sector that, although still limited, is gradually expanding. This paper explores whether the Industrial Internet of Things (IIoT) can provide a realistic pathway forward. It argues that a carefully planned, step-by-step implementation of IIoT technologies—such as real-time grid monitoring, predictive maintenance, and smart metering—could significantly improve the performance of the power system. The proposed roadmap aligns technical advancement with Sudan’s financial and institutional constraints. Studies indicate that a systematic IIoT rollout could reduce system losses by 8–12% over a 3–5-year horizon and enhance grid reliability and resilience, particularly by supporting smart microgrids that deliver power to remote areas.
A Literature Review on Distributed Generation for Application in the Sudanese Grid
This study investigates the potential of distributed generation (DG) as a solution to Sudan’s electricity challenges. The assessment is based on official national data to ensure accuracy and consistency. Sudan’s energy mix is dominated by biomass (56%) and oil (39%), while hydropower contributes only 5%, and renewable electricity remains limited. Although the country possesses significant energy resources, electricity shortages persist due to inefficiencies, as only 76% of generated energy is effectively utilized, while approximately 24% is lost. The residential and industrial sectors account for the highest electricity consumption. The findings highlight distributed generation as a practical approach to reducing system losses, improving grid reliability, and enhancing energy sustainability in Sudan
Integrated Design of a Furfural Manufacturing Process from Bagasse
Conservation of natural resources and pollution reduction are key elements in achieving sustainability. Furfural is one of the most promising sustainable platform chemicals for producing a variety of value-added products. Several studies have been published to optimize the performance of furfural plant design; however, this research introduces an innovative improvement in process integration. Both heat and mass integration strategies were investigated to enhance process efficiency, in addition to conducting an economic evaluation of the proposed plant. Simulation results using Aspen Plus V11 demonstrate that applying mass integration conserves 45% of the total fresh resources while enhancing profitability by saving approximately 0.5 million USD annually. The synthesis of Heat Exchanger Networks (HENs) resulted in total utility savings of 0.02 million USD annually. The proposed plant for producing furfural from sugarcane bagasse is commercially attractive, with a total capital investment estimated at 29.05 million USD and a net present value (NPV) of 19.29 million USD. Overall, profitability metrics including rate of return, payback period, equivalent annual annuity, and NPV sensitivity analysis indicate the economic viability of the plant.
From the Ashes of War to the Dawn of Digital Reconstruction: How Open-Source Technologies are Shaping the Future of Post-Conflict Recovery
Post-conflict nations face immense reconstruction challenges, including destroyed infrastructure, scarce resources, and collapsed governance. Traditional reconstruction models are often slow, expensive, and create technological dependency. This research explores the pivotal role that open-source technologies (OST) can play in providing flexible, sustainable, and low-cost solutions to these challenges. This paper employs an analytical review of academic literature, international reports, and comparative case studies from Syria, Ukraine, and Rwanda. A PEST (Political, Economic, Social, Technological) framework was used to analyze the opportunities and risks of adopting various OST categories, including Geographic Information Systems (GIS), 3D printing, and blockchain for open data initiatives. The analysis revealed that tools like QGIS and OpenStreetMap enable eﬃcient damage assessment, while 3D printing offers rapid solutions for shelter and prosthetics. Blockchain and open data platforms, such as Ukraine's DREAM system, enhance transparency and combat corruption. Key advantages include radical cost reduction, enhanced transparency, and local capacity building toward digital sovereignty. However, significant challenges such as cybersecurity vulnerabilities (e.g., supply chain attacks), the total cost of ownership, and a persistent digital skills gap must be strategically managed. Open-source technologies present a transformative paradigm for reconstruction centered on collaboration, transparency, and local empowerment. Realizing this potential requires a supportive national strategy, sustained investment in human capital, and effective community engagement. This approach can enable nations to not only rebuild but also to establish a foundation for a more resilient, equitable, and digitally sovereign future.
Assessing Rainwater Adequacy for Crop Cultivation under Varying Rainfall Probabilities in the Blue Nile Region, Sudan
The amount of rainfall and the period between rainfall events play a fundamental role in watering rainfed crops, thereby improving productivity. rainfed agriculture in Blue Nile region is one of the important areas in the Sudan. This study evaluated the adequacy of seasonal rainfall compared to crop water requirements for major rainfed crops grown in the Blue Nile region under five climatic conditions: wet, semi-wet, normal, semi-dry, and dry seasons. Daily climate data were obtained from Sudan Metrological Authority (SMA) records during the period from 1971 to 2021. Start, end and length of the growing season were determined for the five season types. Rainwater before, during and after the growing season was calculated. Seven summer crops were studied, namely: sorghum, millet, sesame, sunflower, groundnuts, soya bean and cotton. Crop life cycle, length of growth stages and crop coefficients were used to calculate ETc. The results indicated that while early-season rainfall often meets crop demands, mid and late-season deficits are common, particularly in semi-dry and dry seasons. Though total rainfall was adequate, its uneven distribution underscores the necessity for using suitable crop management and soil moisture conservation practices. The study concluded that all studied crops are viable under current rainfall regimes in Blue Nile region, however, suitable crop management and soil moisture conservation practices have to be considered during mid and late season.
الحقوق الفكرية (c) 2025 https://creativecommons.org/licenses/by-nc-nd/4.0
Mapping of Center-Pivot Irrigation Systems in Sudan Using Remote Sensing and GIS Techniques: A Case Study of the Al Waha Project
This paper presents the mapping of center-pivot irrigation systems in Sudan using remote sensing and GIS techniques to support national and regional agricultural auditing, water and energy use management, and policy development. Landsat-8 imagery with 15 m spatial resolution was employed to identify and map individual pivots. A total of 1,373 active pivots covering approximately 70,078.2 ha was recorded in 2020, located in the River Nile, Northern, Khartoum, Kordofan, and Gazira states (774, 296, 248, 49, and 6 pivots, respectively). A detailed case study of a commercial agricultural project in Khartoum State documented an increase in pivots from 29 to 105 between 2009 and 2020, respectively covering about 5,972 ha. The calculated map accuracy was 96.4% and NDVI was demonstrated to delineate planted area and evaluate within-pivot biomass. Map layers of irrigation networks, soil types, and crop distribution were prepared, showing that the project is irrigated by Blue Nile pump stations and canals; soils are classified mainly as loam and sandy-clay-loam, and Rhodes, alfalfa and corn are cultivated on 79, 20 and 6 pivots, respectively. The pivots consumed both water and energy; an estimated 3,625.83 m³/ha-year (water) and 176.7 L/ha-year (diesel) for alfalfa, while an estimated 3,429.84 m³/ha-year (water) and 167.1 L/ha-year (diesel) for Rhodes. The estimated irrigation efficiency based on CROPWAT/CLIMWAT revealed seasonal variations; alfalfa averaged ~70% (57–87%), while Rhodes averaged ~77%, peaking at ~99–100% in July–August and declining to ~49–55% in September–October. This study demonstrated the opportunity of using RS and GIS derived data to provide direct agro-informatics insights and support more efficient management of water, energy and other applications, thereby strengthening agricultural decision-making, improving productivity, and enhancing resource sustainability in Sudan.
Growing Season Characteristics under Varying Rainfall Probabilities in the Blue Nile Region, Sudan
Rainfed agriculture is central to food security and livelihoods in Sudan, particularly in the semi-humid zones such as the Blue Nile Region where rainfall patterns dictate crop success. This study analyzes growing season characteristics under five rainfall probability levels (20%, 40%, 50%, 60%, and 80%) using 51 years (1971–2021) of rainfall and evapotranspiration data. Monthly rainy days were categorized by intensity, and seasonal rainfall amounts were analyzed across probabilistic classifications. Results indicate that the wet season (20% probability) experiences the highest rainfall and the longest growing season (154 days), while the dry season (80%) is limited to 111 days. Rainfall distributions follow a bimodal pattern with predominance of low-intensity events and limited moderate rainfall. Pre-season and post-season rainfall have significant implications for field accessibility, crop quality, and harvest efficiency. The study highlights the need for early field preparation, improved crop varieties, and conservation agriculture practices to mitigate climate risks and optimize productivity in the face of increasing variability.
Effect of Load Variation on a Voltage-Source Grid-Connected Inverter for a Solar Photovoltaic System
Voltage source grid connected inverter (VSI) of 250 kW has been designed and simulated to be synchronized with a grid of 33 kV using a new designed control unit capable of controlling a photovoltaic (PV) system on both DC and AC sides. The control unit is capable of performing maximum power point tracking technique (MPPT) and DC voltage regulation at the DC side. On the AC side, it controls the pulse width modulation (PWM), current regulation and the phase lock loop (PLL). The design has been performed by preparing the inputs, forming the mathematical equations and simulating them via MATLAB/Simulink package. Results showed that the controller is capable of managing load variation effects on DC side of the PV system. Several changes have occurred on the AC side due to the load variation. A detailed analysis of the results is presented and discussed.
Comparison of Reactors for Hydrogen Production via Methane Steam Reforming: A Review
Methane Steam Reforming (MSR) remains the dominant technology for hydrogen production due to its high efficiency and economic viability. This paper provides a comparative analysis of different reactors used for MSR, including fixed-bed reactors, fluidized-bed reactors, microreactors, membrane reactors, and sorption-enhanced reactors. Fixed-bed reactors are widely employed in industrial settings for their simplicity and robustness, but they face limitations s in heat transfer and equilibrium-constrained methane conversion. Fluidized-bed reactors address these issues by improving heat and mass transfer, but they introduce complexities related to catalyst attrition and operational control. Microreactors leverage their high surface area-to-volume ratio to achieve excellent heat transfer and reaction kinetics, making them ideal for small-scale and portable applications, albeit with limited throughput for large-scale operations. Sorption-enhanced reactors further enhance hydrogen production through in-situ CO₂ capture, enabling methane conversions of up to 85% and hydrogen purity exceeding 95%, though sorbent regeneration poses technical barriers. Finally, membrane reactors integrate hydrogen separation with the reforming process, shifting equilibrium towards higher methane conversion and hydrogen yield, though the high cost and stability of palladium-based membranes remain challenges. The study highlights the challenges faced by these reactor technologies, including catalyst performance, economic constraints, and scalability issues, while discussing future perspectives such as the integration of renewable energy sources, and advanced catalyst development. Advancements in these areas will be crucial for enhancing the efficiency, cost-effectiveness, and sustainability of MSR processes, paving the way for cleaner and more reliable hydrogen production.
Modeling Dust Storm Impacts on PV System Performance in Arid Regions: A Case Study of Sudan
This study presents a mathematical model to predict the impact of dust storms on solar irradiance and photovoltaic (PV) system performance, with a focus on arid regions like Sudan. Using LiDAR data and locally collected dust samples, the model analyzes the relationship between dust particle-size distribution (PSD), extinction coefficients, and visibility. Results indicate that dust storms significantly increase optical depth and light attenuation, particularly at low sun elevation angles, leading to substantial reductions in solar irradiance. The proposed model incorporates optical and meteorological parameters—such as normalized polarizability, visibility, and particle density—within a semi-analytical framework. Unlike traditional empirical models, this approach integrates region-specific dust properties and particle physics, enhancing predictive accuracy for PV output losses. The model predicts irradiance losses of up to 50% during severe dust events, aligning well with reported field observations from similar environments in the Middle East and North Africa. This work contributes a valuable tool for solar energy forecasting and system planning in dusty regions. It also offers insights into visibility degradation during dust storms, supporting applications in both energy and environmental monitoring
Geospatial Information: A Success Factor for Sudan’s Hydrologic Investigations
Hydrologic investigations and analyses are essential components of any water resources assessment. Traditionally, these investigations require significant time, effort, and financial resources. However, the emergence of remote sensing techniques, along with geospatial data and information, has provided new sources of hydrological data and significantly enhanced the capabilities of water resources assessments. The primary objective of this article is to highlight the significance of geospatial data and information in the success of hydrologic investigations and hydraulic designs. The study also provides valuable insights for assessing the current situation and guiding future research. Elevation data are derived from the local surveying measurements and the default Advanced Land Observing Satellite (ALOS), World3D (AW3D), and Digital Elevation Model (DEM) readings. This paper demonstrates that feasibility studies for water harvesting projects can be effectively conducted using geospatial and remote sensing data. As an illustration of the potential of these technologies, a case study is presented, detailing hydrologic investigations and engineering designs for multiple water harvesting projects and water supply systems serving 14 towns and 26 villages in West Kordofan State, Sudan. Based on the outcomes of this study, the authors recommend the development of a unified geospatial information system for hydrology, water resources, water harvesting for agriculture and animal production, and for the production of flood risk maps in Sudan
Internet-Based Experiments for EEE Education in Sudan: Opportunities and Roadmap
This paper examines the role of internet-based technologies in rebuilding, modernizing, and sustaining electrical and electronic engineering (EEE) education in Sudan. Amid infrastructure collapse and limited resources, virtual, remote, and hybrid laboratories offer practical alternatives to traditional lab environments. The study reviews global case studies and presents a phased implementation strategy suited to Sudanese universities—beginning with virtual simulations, expanding to kit-based hybrid labs, and culminating in shared remote lab networks. A SWOT analysis identifies key enablers and risks. While challenges such as internet access and faculty training persist, online labs represent a strategic opportunity to restore and future-proof EEE education in post-conflict settings.
Assessment and analysis of the performance of Multi-Hop Internet of Underwater Things Networks
This study aims to evaluate the performance of multi-hop Internet of Underwater Things (IoUT) networks under varying environmental and network conditions. The Internet of Underwater Things (IoUT) is a technology that contributes to building smart cities, but it must overcome several challenges, including environmental concerns, connectivity barriers, and system architecture complexities. This paper presents a performance analysis of multi-hop Internet of Underwater Things Networks. We examine and assess the performance of multi-hop IoUT networks in terms of several key metrics, including throughput, network efficiency, packet loss rate, and signal-to-noise ratio (SNR). The analysis provides valuable insights into the capabilities and limitations of multi-hop IoUT networks.
Application of Controlled Switching to Reduce Switching Over-voltages on EHV Transmission Lines
This study investigates the effectiveness of controlled switching techniques in reducing switching over voltages on EHV transmission lines. The case study is the Sudanese 500 kV transmission line connecting generation at Merawi to the load centre at Khartoum (Sudan). The method used is modeling and simulation the line using MATLAB/SIMULINK. The results show that the phase-controlled switching technique is far superior to the Pre-insertion Resistor (PIR) method. It is also found that switching over-voltages are very much reduced when Metal-Oxide Surge Arresters (MOSA) are installed at the line ends and also when the transmission line is compensated.
Design and Implementation of a Power Supply for Hearing Aids Based on Human Thermal Energy
This paper presents a prototype of a thermoelectric harvester generator designed to convert the waste heat generated by the human body (specifically, the skin) into electrical energy, which.can be used to power a hearing aid unit using renewable energy. The method used for harvesting thermal energy from the human body is based on the principles of the Peltier effect, which is a type of thermoelectric effect. The proposed model consists of three main components: generation, amplification, and hearing aid. The required number of Peltier elements and the skin area have been specified. Additionally, the results demonstrate that the generated energy is influenced by the device’s placement on the body and ambient temperature. Additionally, the results demonstrate that the generated energy is influenced by the system's location on the human body and the ambient temperature
Performance of Thermal Power Plants in Tropical, Dry, Temperate, Continental, and Polar Climate Regions
The influence of climatic conditions on thermal power plant performance has been insufficiently addressed in existing research. This study investigates how different climate zones affect plant efficiency, resource use, and environmental impact. A 100 MW thermal power plant operating on the ideal Rankine cycle with superheat and reheat is used as a representative case study. Thirty years (1991–2021) of climate data from 92 global locations representing tropical, dry, temperate, continental, and polar regions are analyzed using Engineering Equation Solver (EES) software. Results show that tropical climates have ambient temperatures higher by 4°C, 10°C, 17°C, and 26°C compared to dry, temperate, continental, and polar regions, respectively. Plants in tropical and dry regions show a 1.0%–3.0% drop in efficiency, 12.0%–30.0% higher makeup water demand, 5.0%–11.0% greater cooling water needs, and 3.0%–6.5% increases in fuel consumption and CO₂ emissions. These outcomes highlight limitations and underscore the need for the importance of transitioning to renewable energy sources to enhance energy sustainability and water resilience.
Estimating the Normalized Polarizability of a Dusty Medium by Using Elliptic Integrals
Microwave signal degradation during dust storms poses significant challenges for high-frequency communication systems, especially in arid regions. Traditional models often assume spherical dust particles, which limits their accuracy in representing real-world propagation effects. This paper presents a theoretical model to estimate the normalized polarizability of dusty media by incorporating non-spherical particle geometries. Specifically, dust particles are modeled as ellipsoids, and their geometry factor is analytically determined using elliptic integrals. The model integrates this shape-dependent factor into the Maxwell-Garnett effective medium framework to evaluate the dielectric properties of dusty environments. Key contributions include: (1) the derivation of depolarization factors using elliptic integrals for arbitrary ellipsoidal geometries, (2) a shape-sensitive dielectric model accounting for orientation and volume fraction, and (3) a parametric study demonstrating the impact of axial ratios and dielectric contrast on normalized polarizability across microwave frequency bands. This work provides a compact analytical formulation that enhances the prediction of electromagnetic behavior in dusty atmospheric conditions, offering practical value for communication system design
Historically Acacia seyal gums in the Sudan is ranking as a second important gum product after A. senegal in terms of quantities 10% in average until 2011. Thus the contribution percentages within the last four years (2012-2015) jumped to almost 60% in average. A. seyal trees coverage extend in an area of 36,000 square kilometers (3.6 million ha) in a latitude ranging between 10 to 140North. The distribution of the A.seyal stand is extensively on the clay soil plains where an average rainfall is ranging between 300 to 400 mm. Two infraspecific variants of A. seyal widely distributed in Sudan separated on the basis of the presence and absence of the ant-galls and the colour of the bark. Ant-gall and white colored bark are the characteristics of variety fistula, while the bark of variety of seyal is green or red. Despite the significant contribution of A. seyal in the exports market in the Sudan, farmers have slightly a poor knowledge of post- harvest cultural practices of A. seyal of which proper methods of storage conditions and gum stacking. Nevertheless, this paper is trying to review the existing research in the areas of pre- and post-harvest cultural practices including tree husbandry, tapping, gum collection, handling and storage. Exudation mechanisms (tapping and natural exudation) are also been highlighted coupled with physical and chemical properties of A. seyal (characterization) as well as moisture content, colour, tannins etc., aiming at establishing a clear protocol of the A. seyal tree in the Sudan.
الحقوق الفكرية (c) 2022 University of Khartoum Engineering Journal
The Effect of Radiometric Resolution on Information Sharing Between Landsat8 Bands
The technological revolution that the world is witnessing also included the development of the characteristics of remote sensing devices, which had a direct impact on increasing the accuracy of the data obtained through these devices. For example; the radiometric resolution of Landsat satellite sensors increased from 7 bits in the first Landsat sensors to 16 bits in Landsat-8. In this study, the effect of this improvement in radiometric resolution was measured to find the amount of change in the mutual information at several dynamic ranges. The study area was the state of Khartoum, and the study was conducted on four different types of land cover (agricultural, urban, water, and desert) to determine the amount of shared information between several dynamic ranges based on the land cover unit. The image obtained from the Landsat-8 satellite for the study area had a 16-bit dynamic range. However, it was down sampled to 8bits, 9 bits, 10 bits, 11 bits, 12 bits, 13 bits and 14 bits, and the amount of information shared between these dynamic ranges and the original image was calculated for the first seven bands of Landsat-8. The results showed that the amount of shared information varies based on the type of land cover, however, this amount reaches its lowest value on the water cover between the 8-bit image and the 16-bit image which is 80%. The study ended with a recommendation that the effect of change in radiometric resolution should be examined in the stage classification of images.
الحقوق الفكرية (c) 2023 University of Khartoum Engineering Journal
Causes and Effects of Delays in Road Construction Projects in Sudan
Construction delay is one of the serious concerns of the road industry in Sudan. The study aims to identify the causes of delays that have adverse effects on road projects in terms of time, cost and quality. Literature of different types of delays, their causes and effects on road construction projects were intensively reviewed. The study identified a number of causes of delays at great risk and have adverse effects on construction of road projects. A questionnaire based on 15 causes and 5 effects was sent to the clients, consultants and contractors. The collected data were analysed using the Relative Importance Index (RII). The results showed that the contractor is most commonly responsible for project delay (37%), followed by the client (33%) and the consultant (30%). The study findings reveal that the top five main delay causes are payment delay by client, funding problems, conflicts among the project parties, suspension of work due to the client or consultant, and project schedule changes. On the other hand, cost and time overrun, poor quality of work due to rush, and disputes are the main effects of delays. The study concluded that adequate construction budget and payments on time should be the main factors for the project success.
Comparative Study on Some Chemical and Mechanical Stabilizations of Expansive Soils
This paper studies the differences between effects of chemical and mechanical stabilizations on the engineering properties of expansive soil. Undisturbed soil samples were collected form Abu-Gameem in South Sudan. The soil sample was very high expansive in accordance to the primary test conducted. Laboratory tests were undertaken to study the effect of chemical and mechanical additives individually on soil properties. Atterberg’s limits, compaction, California bearing ratio, free swell and swelling pressure tests were conducted on natural and treated soil. Quicklime was used as chemical stabilizer agent, while fine sand was used as mechanical. The lime was collected from Sabol industrial area in south of Khartoum while the sand was obtained from Omdurman in Sudan. The soil was first treated by quicklime contents as 3%, 5% and 7% by weight. Then separately was treated by fine sand contents as 5%, 10% 15% by weight. Comparing the results obtained from chemical and mechanical stabilizations, it can be reported that both of them are effective in improving the engineering properties of expansive soils. Notwithstanding, chemical stabilization improved the soil with less contents of additive. Addition of only 3% quicklime reduced soil plasticity from 45% to a suitable value (18%) while addition of 15% fine sand reduced soil plasticity to 24%. Addition of quicklime resulted in reduction of free swell index almost 4 times of its initial value, whereas slight reduction was observed when fine sand used. Significant improvement on the swelling pressure was obtained when using lime. But, the compaction characteristics were improved further when fine sand used. It could be concluded that based on the result of this study, chemical stabilization is more effective than mechanical. However, a combination of them can be used for further investigations.
Design and Implementation of a Universal Integrated Wi-Fi Controller for Smart Buildings
Internet of things (IoT) technologies deal with the control over communication networks for different applications of different fields, such as residential buildings, commercial buildings, agricultural farms, transport vehicles, and manufacturing industries. Wi-Fi is a family of protocols for wireless local area networks, based on the IEEE 802.11 standards. Recently, a microcontroller with a built-in Wi-Fi module can be considered one of the most recent technologies of IoT. Nevertheless, most of the available research on Wi-Fi controllers is dedicated to a specific application. This paper aims to design and implement a universal hardware platform for a Wi-Fi controller that can be integrated with multiple applications for residential and commercial buildings. The proposed system is based on Ep8266 NodeMCU with a built-in WiFi module. Input modules and output modules of the proposed system are designed to be suited for various voltage levels. The proposed system was implemented and evaluated for multiple applications. The first application deals with controlling residential building loads with an embedded web server on the Wi-Fi controller and web browser on smartphones. The second one is related to integration with the remote access control application of commercial buildings, which is based on Radio Frequency Identification (RFID) cards with Wiegand protocol and based on User Datagram Protocol (UDP) with Internet Protocol (IP).
Banana Extract Lateritic Soil Stabilization in Sudan
Soil stabilization otherwise known as soil modification or improvement, is the process of modifying soil properties to render them durable building and road construction materials by using various admixtures, the well-known being cement and lime. The aim of this study, however, to examine the stabilizing effect of banana extract on selected Sudanese lateritic soils. The objective of this study is to develop a new process for stabilizing lateritic soils. The three soil samples were blended with banana raw extract at 17% by weight of the dry soil at optimum extract content (soil + banana solution). High degree of improvement was obtained in both dry (12.60 – 30.54 N/mm²) and wet (1.03 – 5.03 N/mm²) compressive strength. It was concluded that, banana extract has a profound modifying effect over lateritic soils.
Mohammed Salih Mohammed Khalid M.Elmadni
Impact of Grand Ethiopian Renaissance Dam (GERD) on Manufacturing of the Traditional Fired Clay Bricks in Sudan
The Grand Ethiopian Renaissance Dam (GERD), one of the largest dam projects in the world is currently under construction on the Blue Nile River reach in Ethiopia. Such a massive project will have positive and negative impacts on downstream countries like Sudan. These impacts include impounding sedimentation and avoiding flood occurrence. Previous researches indicated that GERD is expected to impound up to 86% of the Blue Nile annual sediment yield. This is expected to adversely affect the manufacturing of traditional fired clay brick (TFCB) at the banks of both the Blue Nile and the Main Nile rivers. The aim of this paper is to study the impact of GERD on TFCB industry which utilizes the sediment as the main raw material in brick manufacturing. Based on the literature and brick market survey, it has been found from this study that the produced TFCB could be reduced by 68.8% following GERD. This reduction in TFCBs is expected to affect more than 170,000 workers around the country. Future studies and market plans are needed to fill the gap of the TFCB shortage.
Forecasting of Data Traffic in Sudan Internet Exchange Point Using Autoregressive Integrated Moving Average Model
Network traffic prediction is an important issue that has received much interest recently from computer network community. The network traffic prediction is one of the typical issues useful for monitoring network, network security, avoid congestion and increase speed of networks. Different techniques are used for network traffic prediction; first are linear time predictors such as Last Value (LV) Predictor, Windowed Moving Average (MA), Double Exponential Smoothing (DES), Auto Regressive (AR), Autoregressive Moving Average (ARMA) and Autoregressive Integrated Moving Average (ARIMA). The Second techniques are nonlinear time predictor such as generalized autoregressive conditional heteroscedasticity (GARCH) and the last one is hybrid model techniques, and it is combination between two or more models. From literature review, the ARIMA model is the best model to predict data traffic that has time series specification and linear growth. Data traffic collected from Sudan Internet Exchange Point (SIXP) and ARIMA is used to model data and forecast the next five years values. In addition to forecasting values, upper, and lower values are also founded. Furthermore, ARIMA model findings are compared with Monte Carlo forecast and it is found that the results are nearly typical. Finally, when the forecasted results are compared to actual data traffic on January 2020, the predicted values are shown to be very close to the measured ones.
Economic Analysis and Policy-Related Recommendations to Promote Distributed Solar Photovoltaic Systems in Sudan
Distributed solar photovoltaic (DSPV) is a practical and reliable solution in the case of Sudan, considering the vast and remote off-grid rural areas and the insufficient electricity generation in the parts powered by the national provider. This research outlines the scientific processes to work out the economic appraisal of an off-grid PV system with and without storage units that could be deployed within Greater Khartoum. The provided financial assessment, which relies on the PV price, the annualized monthly bill savings, the Levelized cost of energy, the simple payback period, and the national and regional kilowatt-hour tariffs, delivers an insight into the cost affordability of solar-generated electric power in Sudan. Accordingly, the analysis concluded that approximately 1.6 $/Wp is the PV price for a system with a battery bank and 1.2 $/Wp for the on-grid option, both to be fixed in the residential sector. However, the designed system here will not pay back the initial cost considering the low local electricity price. Also, considering the status quo, the investment will not attract investors in the energy sector, although it compensates for the frequent power deficiency in times of need. On the other side, the effort presents local experts and leaders in energy research and planning recommendations to encourage the governmental facilitation of DSPV use as viable renewable energy (RE) technological option. These recommendations hover around the issuance of country-level PV energy policies and are categorized into financial, policy, social, and technical. This work's novelty is its contribution to developing and supporting the Sudanese literature in the energy field, in which the lack of resources and content specific to the republic, especially RE, is evident.
Design and Construction of an Absorption Cooling System Driven by Solar Energy
The objective of this work is to design and construct a lithium bromide–water (LiBr-H2O) absorption cooling system with a nominal capacity of approximately 1 TOR driven by solar energy which uses Lithium Bromide as absorbent and Water as refrigerant. The proposed absorption cooling system comprises a roof-mounted vacuum tubes solar collector, a single-effect LiBr–H2O absorption chiller (generator, a solution heat exchanger, an evaporator, a condenser, and an absorber),fan coil unit, a cooling tower, pumps, flow throttling and controlling valves. A thermodynamic analysis of the absorption cooling cycle has been performed to study the effect of various operating conditions on the thermal performance. Results from experimental work carried out in Khartoum City during October 2015show that the COP of the absorption cooling system ranged from 0.57 to 0.64 while the Chilled water temperatures mostly ranged between 17°C to 19.5°C. Condensation and absorption temperatures were under 45°C while the maximum temperature of the driving water is 83°C. The results also show that the generator temperature had a great effect on the performance of absorption and solar collector systems.