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There has been a significant increase in attention toward designing smart structures and vibration control of structures in recent decades, and numerous methods and algorithms have been developed and experimentally investigated. However, the majority of these studies used the shear frame models to represent structures. Since the simplified models do not reflect the realistic behavior of those structures with irregularity in plan and elevation, the traditional methods for designing an optimal control that guarantees a desirable performance is impossible. In this study, the behavior of a 10-story irregular steel frame building is investigated with and without controlling systems. Two pairs of eccentrically placed MR dampers on each story are used in order to mitigate the coupled translational–torsional vibration. The controlling forces are determined using active, passive-off, passive-on, and clipped optimal controls based on the linear quadratic regulator (LQR) algorithm. The results demonstrate that using pairs of magneto-rheological (MR) dampers with an appropriate distance on lower story levels significantly reduces the inter-story drifts for the corner columns, as well as the roof displacements and accelerations.

Small wind turbines have the potential to provide a significant amount of useful electricity; particularly in urban areas where it is necessary to use self-supporting monopole towers. Their take-up can be increased by reducing tower costs. The numerical optimisation technique called differential evolution (DE) was used to design a minimal mass self-supporting tower for a 5 kW wind turbine, whilst retaining the required strength and stability. The main problem in the optimisation was the limited availability of appropriate simple equations for buckling analysis of the chosen octagonal geometry as required for design certification to the appropriate international standards. Performing linear buckling analysis (which is unsuitable for global optimisation) on towers designed to meet the available buckling equations showed that the buckling strength was significantly overestimated for low wall thicknesses. A correction factor was formulated and applied to the existing buckling equations to remove this inconsistency. DE was then used to design a tower that was 7% lighter and 20% more resistant to buckling than the current reference design.

Faults in electrical facilities may cause severe damages, such as the electrocution of maintenance personnel, which could be fatal, or a power outage. To detect electrical faults safely, electricians disconnect the power or use heavy equipment during the procedure, thereby interrupting the power supply and wasting time and money. Therefore, detecting faults with remote approaches has become important in the sustainable maintenance of electrical facilities. With technological advances, methodologies for machine diagnostics have evolved from manual procedures to vibration-based signal analysis. Although vibration-based prognostics have shown fine results, various limitations remain, such as the necessity of direct contact, inability to detect heat deterioration, contamination with noise signals, and high computation costs. For sustainable and reliable operation, an infrared thermal (IRT) image detection method is proposed in this work. The IRT image technique is used in various engineering fields for diagnosis because of its non-contact, safe, and highly reliable heat detection technology. To explore the possibility of using the IRT image-based fault detection approach, object detection algorithms (Faster R-CNN; Faster Region-based Convolutional Neural Network, YOLOv3; You Only Look Once version 3) are trained using 16,843 IRT images from power distribution facilities. A thermal camera expert from Korea Hydro & Nuclear Power Corporation (KHNP) takes pictures of the facilities regarding various conditions, such as the background of the image, surface status of the objects, and weather conditions. The detected objects are diagnosed through a thermal intensity area analysis (TIAA). The faster R-CNN approach shows better accuracy, with a 63.9% mean average precision (mAP) compared with a 49.4% mAP for YOLOv3. Hence, in this study, the Faster R-CNN model is selected for remote fault detection in electrical facilities.

Energy harvesting from the environment becomes a valuable technology, especially for sea wave applications, in which it usually ends up wasted despite its potential to be harvested. Due to its wide availability and high energy density, piezoelectric energy harvesting (PEH) is becoming popular for flexible energy harvesting. This paper presents a flexible horizontal piezoelectric (FHP) energy harvester to harvest energy from the surface of sea wave. The harvester is made of bimorph piezoelectric devices; they are utilised to amplify and convert the collected mechanical vibrations into electrical power. A finite element model is established from ANSYS simulations to solve the iteration method by generating resonance frequency (fr). Then, Taguchi method, SN ratio and the ANOVA approach were used by considering the input variable of fr to estimate the optimum performance through control factors; number of blade, length and thickness. From the performance test result, it is proven that the higher numbers of blade including length, and minimum numbers of thickness significantly improve the significant level, α = 0.05% of ANOVA. Three prototypes are developed with approximate body dimensions through the resonance frequency perform and generate a 160.3 Hz on blade dimensions of 10 × 300 × 0.2 mm, with a piezoelectric (PZT) on its surface. This particular study shows that the potential of output power is generated from sea wave surface through a significant relationship between length, thickness, and blade design. This research develops a novelty for energy harvesting from flexible piezoelectric generator on sea wave application that could be easily install on offshore platform.

The building sector’s sustainability requires construction and demolition waste (CDW) to contribute to the circular economy. Among the CDW, recycled concrete aggregates (RA) have been mainly studied to replace natural aggregates. Still, the approval of their use in regulations and standards is slower. Some barriers to the adoption of RA are related to the durability of recycled aggregate concrete (RAC). However, their physical and mechanical properties have been extensively studied. The durability risks associated with sulfate attacks have been solved for conventional concrete. However, sulfate attack on recycled concrete still raises numerous unsolved questions. In this literature review, the experience of sulfate attack on RAC is compiled and analyzed using a compressive framework highlighting the most relevant aspects of the new matrix in RAC and the old matrix of RA to support its relevance to the damaging sulfate process. Suggestions for further research are presented to understand the full extent of this issue and contribute to incorporating and extending recycled aggregates into existing regulations.

In order to explore the fracture evolution characteristics of existing defect lining structures under unsymmetrical loads, unsymmetrical failure model tests of three working conditions, namely, intact lining, vault defect, and arch waist defect, were carried out. Acoustic emission (AE) technology was used to detect the lining cracks from microscopic to macroscopic. The relationship between the accumulated energy of AE and the relative load was established, and a fracture evolution model of lining based on the cumulative energy of AE was proposed. The results show that the failure process of the intact lining under unsymmetrical load has three stages: “initial crack cracking at the unsymmetrical position → development and formation of main crack → specimen cracking failure”. The load ratio of initial crack cracking is 16.5%, and the load ratio of main crack development and formation is 52.2%. The initial cracking position of the lining under unsymmetrical loads has nothing to do with the existing defect position, with defects occurring at the unsymmetrical position, and the remaining cracks are mainly distributed in the vault, inverted arch and arch foot position. Compared with the intact lining, the ultimate bearing capacity of the vault defect and arch waist defect decreased by 14.2% and 21.3%, and the maximum deformation decreased by 44.6% and 50.6%, respectively. The radial deformation degree in the unsymmetrical position at each stage is basically the same under unsymmetrical load conditions, and it is not affected by the position of the existing defects. The deformation proportion of each stage is concentrated in 5%, 40%, 53%, respectively. We derived the facture evolution of lining based on the accumulated energy of AE, and the quantitative relationship between the damage variable and deformation of the lining under unsymmetrical load was established. When the fracture degree reaches 0.04 and 0.35, the deformation of vault defect lining and the arch waist defect lining is 58.3%, 75.0%, 40.2% and 50.6% earlier than those of the complete lining, respectively. When the fracture degree exceeds 0.6, the growth rate of damage degree is no longer affected by the location of the existing defect.

In light of the rapid development of electrified railways, the safety and stability of train operations, as well as the catenary’s interaction with current quality, have garnered widespread attention. Electrified train operation with additional track irregularities serves as a principal excitation source within the vehicle–bridge–catenary system, significantly influencing the vibration characteristics of the system. Addressing the aforementioned issues, we first established the vehicle–track dynamics model and the bridge–catenary finite element model based on the principles of coupled dynamics of the vehicle–track system. These models are interconnected using dynamic forces between the wheel and rail. Subsequently, within the vehicle–track coupled system, track random irregularities are introduced as input excitations for the coupled model, and the dynamic response of the system is simulated and solved. Then, the obtained wheel–rail forces are applied to the bridge–catenary coupled system finite element model in the form of time-varying moving load forces. Finally, the dynamic response characteristics of the catenary portal structure under different conditions are determined. Meanwhile, a study on the vibration characteristics of the truss-type pillar portal structure was conducted, and the results were compared with those of existing models. The results indicate that the vertical and lateral forces between the vehicle and track are positively correlated with the speed and irregularity amplitude. Response values such as the derailment coefficient and wheel load reduction rate are within the specified range of relevant standards. The low-order natural resonant frequency of the truss-type pillar structure has, on average, increased by 0.86 compared to the existing pillar structure, which signifies improved stability. Furthermore, under various conditions, the average reductions in maximum displacement and stress response of this pillar structure are 13.2% and 14.19%, respectively, in comparison to the existing pillar structure, rendering it more suitable for practical engineering applications.