International Journal of Engineering Research in Africa Vol. 61

Abstract: Cities all around the globe are ramping up efforts to transform their infrastructure in order to achieve a carbon-neutral and sustainable future, resulting in fast electrification of transportation networks. The need for power in this industry is rising, notably in light rail transit. Application of train rooftops wind energy conversion has the potential to power light rail transits with renewable energy. This research paper presents a way to generate electrical energy by utilizing strong wind pressure from light rail trains that channels the induced wind towards the turbine. The current invention's main aim is to establish a method and system for producing energy utilizing winds that can be conveniently available in the operation of trains. Here the wind energy is independent of the variations in the direction and speeds in which seasonal winds move, which do not have the appropriate wind force or force at all times or places for operating the wind turbines. Vertical axis wind turbines are selected due to their advantage for the application under consideration. SOLIDWORKS and MATLAB simulation software were used for the design of the Train Roof-Tops Wind Energy Conversion System (TRT-WECS). The former was used to perform computational fluid dynamics (CFD) on the both normal train as well as the train having a turbine installed on the top, and a comparison has been made in terms of various parameters that affect the performance of the newly designed TRT-WECS. A mathematical model comprising mechanical and electric components has been developed by using MATLAB. Finally, the study found out that this special TRT-WECS design installed in each train provides an annual energy output of 4.9 MWh.

Abstract: Facing development requirements and changes in the global energy context, Morocco has begun a process of diversification of the national energy mix in favor of renewable energy, while ensuring a competitive energy, in terms of costs, availability of products and their security and sustainability. Within this framework, Morocco launched in 2009 a national energy strategy whose major orientations focus on the security of energy supply and the generalization of its access, the preservation of the environment, through the use of renewable energy, energy efficiency, the strengthening of interconnection and regional cooperation. Through this article, the current state of the Moroccan network will be studied, as well as its potential in terms of renewable energy. Some strategies to overcome the challenges facing smart grid deployment in Morocco will also be presented. Then, the long-term energy demand, generation capacity, and renewable energy evolution in Morocco around 2030 will be estimated based on a time series using the artificial neural network method, which can be injected into the grid without causing any transit restrictions on the utility network or on the whole power system. As a result, the wind power available capacity was estimated to be 4087 MW, and the solar power available capacity was estimated to be 4713 MW by 2030. These results will be then compared to those estimated with the mathematical method. As well as, with the accuracy results of similar studies with different time series forecasting techniques. The accuracy value of this study is between 1.2% and 3.5%. So, the performance and viability of the proposed model can be studied.

Abstract: Different fines of rice husk ash (RHA) are typically used as a binder for soil stabilization. This study aims to assess the performance of RHA fines as a binder with lime in the improvement of plasticity and compaction characteristics of stabilized soil. Consistency limits, particle sieve analysis, and compaction tests were conducted on the natural lateritic soil, while consistency limits and compaction tests were conducted on the stabilized lateritic soil. The tests conformed to BS 1377 (1990). The chemical compositions of the RHA were assessed. Lateritic soil samples were mixed with lime in the proportions of 2, 4, 6, 8, and 10% by weight of dry soil. Plasticity Index (PI) was used as the determinant of optimum performance of lime-stabilized lateritic soil and this was obtained at 8% of lime addition. Thereafter, binder ratios (Lime: RHA) of 0:8, 2:6, 4:4, 6:2, and 8:0 were employed in the blending of the lateritic soil. The Plasticity Index (PI) of the stabilized soil were generally lowered to 7.82%, 21.36%, 18.97%, 19.71%, 15.03% when stabilized with BR2:6₇₅μm, BR4:4₇₅μm, BR6:2₇₅μm, BR2:6₃₀₀μm and BR6:2₃₀₀μm respectively. All binder ratios containing both lime and RHA size of 75 μm reduced the PI. Also, the effect of all binder ratios containing both lime and all RHA sizes showed increment in the Maximum Dry Density (MDD). Similarly, soil stabilized with BR2:6₁₅₀μm, BR4:4₇₅μm, BR4:4₁₅₀μm, BR4:4₃₀₀μm, BR6:2₁₅₀μm and BR6:2₃₀₀μm offered a lowered OMC. 75μm RHA and BR4:4₇₅μm had the potential to improve Lime-RHA stabilized lateritic soil mixture especially for road application.

Abstract: Engineered unfired clay bricks are an ecological alternative to overcome conventional construction materials’ inconvenience. This work investigates the rheological behavior of organo-silica suspensions, made from almond husk waste and illite clay, in relation to the compressive strength of unfired clay bricks incorporating the same waste. Selected proportions by weight of almond husk are 2, 5, 10, and 20 wt.%. Results from the compressive strength test show an improvement, of 8.98% in bricks with 2 wt.% waste content compared to the control sample, thanks to an increase in friction and the fiber bridging mechanism. Then, a progressively decrease in strength is recorded with the addition of waste. The decrease in strength is reported to be the creation of pores in the matrix, and loss of cohesion. It is found that the storage modulus, on a logarithmic scale, follows inversely the same trend of the compressive strength in previously prepared bricks. The results from the strength test and rheological test are linearly correlated. Strong coefficients of determination are found; R²=0.9809 (with 40 wt.% water content) and R²=0.9206 (with 50 wt.% water content). The findings from this study demonstrate the possibility of assessment and prediction of unfired bricks’ strength using rheometry.

Abstract: Reliability and behaviour of composite columns is influenced by many factors. This paper presents a comparative study of the reliability and performance of square composite columns under axial compression, taking into account mechanical and geometric variability. The choice is opted for metal hollow profiles filled with ordinary concrete and high-performance concrete. In this study, a mechanic-reliability model to calculate the reliability index and the probability of failure of different columns is presented. The response surface method is used to accomplish this coupling in order to describe the uncertainties in a suitable model and to study their influence for a reliability assessment. The results show that the material and geometric characteristics of the columns have a significant influence on strength and reliability. The sensitivity of the random parameters of structural reliability is assessed from the proposed method.