• Energy Research
• 2025-2025close
• civil engineering close

Wind-assisted ship propulsion is one of the solutions for reducing greenhouse gas emissions by generating additional thrust using renewable wind power. Various technologies utilizing wind power to generate thrust are being developed and adopted by the industry. In addition to the thrust, side forces are also generated as secondary outputs, and they significantly affect ship motion. Although many studies have been conducted on the effects of sails on ship dynamics and energy consumption, the impact of control strategies of wind-assisted ships on energy consumption has not been clearly identified. This study aimed to determine the bearings of different control strategies on ships in terms of motion and energy. When the heading control strategy is adopted, rotor sails can reduce energy consumption by up to 10%. However, course- and speed-controlled ships without any wind-assistance devices can reduce energy consumption by 15%, and a further reduction of up to 30% can be achieved through rotor sails depending on the wind direction. When the control of the rotor sails was changed from a stand-alone controller to a ship dynamics-integrated controller, the energy consumption can be reduced by approximately 1-2% for course- and speed-controlled ships.

The tube structures designed in the multicell pattern are used for crashworthiness in many areas. In this study, the crashworthiness was designed by dividing the inner area of the circular section geometry into equal slices by examining previous studies. In addition, this structure was prepared as a dual gradient in two different sizes along the length. Performance parameters were investigated by performing theoretical and numerical analyses. For multicell crashworthiness, which is considered a dual gradient, the folding style was insufficient in lobe formation. However, the specific energy absorption (SEA) and the crushing force efficiency (CFE) values of the two types of dual gradient structures behaved appropriately in absorbing kinetic energy. The dual gradient new design of crashworthiness provides resistance by preventing the bending of the structure under oblique loading. According to the results of the analysis, the mean SEA and CFE under loading at all angles for the 2nd order dual gradient configuration was 12.88% and 1.61% higher than the 1st order design. However, with the preparation of circular section tubular structures using 8-panel elements, close values were obtained in the comparison of theoretical and numerical analysis under axial loading conditions.

Earthen construction techniques possess without any doubt a rich historical legacy, being able to assess an efficient combination of structural stability, thermal mass properties, and low environmental impact, which leads to their current renewed interest as key direction for sustainable building practices. Additionally, earthen buildings and the associated techniques, related to material, structural design, building solutions, etc., represent key testimonies related to the cultural local and traditional legacies all over the world. Earthen buildings, vernacular or developed by using qualified personnel such as craftsmen and traditional masons, use different techniques and construction technologies (rammed and poured, load-bearing walls, adobe, mixed wood-earth structures, etc.), and were developed differently with respect to the region where they were used. Generally, due to superposition of many factors, the interest towards the earthen materials and techniques in construction areas are gaining popularity. In this context, the aim of this research is to provide an overview of the non-destructive methods used for analysing earthen constructions in terms of structural integrity and overall performance, considering a major focus on rammed and poured earth-building techniques. The current research intends to identify and consider the advantages, limitations, and applications of NDT techniques in the context of earthen construction, also promoting potential further research and development in the field of non-destructive evaluation for earthen materials. Throughout the study, various non-destructive testing methods will be reviewed from the perspective of their actual suitability in the area of materials, element and structure analysis. Case studies demonstrating the practical applications of NDT in earthen structures are emphasised, together with identified challenges in non-destructive testing applied in the considered topic of use.

Innovative use of waste materials has proven to be effective for improving concrete’s technical properties while eliminating the threat of environmental pollution. There is paucity of research regarding the combined use of Waste Steel Fibres (WSFs) and Waste Tire Rubber Fibres (WTRFs) in concrete. Thus, this study aimed to investigate the influence of WSFs and WTRFs as reinforcement in concrete and determine their optimal fractions for enhancing the concrete strength properties using Response Surface Methodology (RSM). WSFs of 0.3-1.5% with a 0.6% increment and WTRFs of 0.3-1.5% with a 0.6% increment by concrete volume as reinforcement in concrete with water-to-cement ratio (W/C) of 0.25–0.65 with 0.2 increment were designed using the Box-Behnken Design of RSM. A total of fourteen (14) concrete mixes with a design strength of 25 N/mm2 were prepared. The fresh and hardened properties (slump, density, water absorption, 7- and 28-day compressive and split tensile strengths) of concrete were determined using standard procedures. The RSM was used to evaluate the interaction between the concrete variables and identify their optimum combination which gave the peak values of responses. Furthermore, the characteristics and sustainability of the concrete under optimum variables were compared with that of the conventional concrete. The outcomes revealed that the inclusion of WSFs and WTRFs yielded concretes with maximum slump, density, water absorption and 28-day compressive and split tensile strengths of 25 mm, 2633 kg/m3, 5%, 41 N/mm2 and 4.54 N/mm2, respectively. The optimization technique showed the optimal variables combination which yielded the peak response values of WSFs (1.40%), WTRFs (0.66%) and W/C (0.54). The nominal variance with the absolute percent error of less than (9%) between the actual experimental verified results and predicted results for all the responses validates the predictability of the model. The split tensile strength and compressive strength increased by 28.33% and 48.85%, respectively at the optimum setpoint of variable with respect to the reference concrete. In addition, the WSFs and WTRFs-reinforced concrete exhibited lower embodied CO2 emission but the embodied energy and cost are slightly higher relative to conventional concrete. Nevertheless, the embodied energy of the concrete was significantly lesser than that of concrete that used individual fibers for reinforcement. Thus, the enhancement of concrete strength properties with the prospect for sustainable fibre-reinforced concrete production through the use of waste steel and tyre rubber fibres is feasible.

Aluminum composite material (ACM) is associated with a high consumption of natural resources, and its production consumes high energy levels and a considerable volume of waste. Given this consequence, alternative solutions for ACM waste are necessary. This work evaluates the chemical, structural, microstructural, and mechanical characteristics of incorporating ACM board waste in producing plaster mortars. The results of the chemical XRF data revealed high concentrations of the calcium system in the ACM mortars. In addition, the XRF analyses showed that the incorporation of ACM affects the homogeneity of the material composition. XRD data showed crystalline phases of Quartz (SiO₂), Portlandite (Ca(OH)₂), Calcinite (CaCO₃), and Ettringite (Et. Ca₆Al₂(SO₄)₃ (OH)₁₂.₂₆H₂O), which were also verified from SEM experiments. In addition, mortars ACM5 and ACM10 presented similar %C concentrations. It was evident that high levels of ACM incorporation substantially increased the %C on the material's surface. These %C concentrations on the surface of the mortars evidence the presence of the polymeric material ACM on the surface of the mortars. Low concentrations of %Si and %Ca on the surfaces of ACM20 and ACM25 also revealed a low presence of SiO2 and calcium systems (Portlandite and CSH). Considering high levels of ACM incorporation in mortars and observing the results, the ACM residue acts as a polymeric coating on the material's surface.