A comparative evaluation of the fatigue damage occurring in the blades of small wind turbines, with different power regulation schemes, has been conducted for the first time. Three representative test cases were built, one based on stall regulation and two using pitch regulation. The power curves were tuned to be identical in all cases, in order to allow for a direct comparison of fatigue damage. A methodology combining a dynamic simulation of a wind turbine forced by stochastic wind speed time series, with the application of the IEC 61400-2 standard, was designed and applied for two levels of turbulence intensity. The effect of the wind regime was studied by considering Weibull-distributed wind speeds with a variety of parameter sets. Not unexpectedly, in typical wind regimes, stall regulation led to a generally higher fatigue damage than pitch regulation, for similar structural blade design, but the practical implications were smaller than thought previously. Given the need for cost-effective designs for small wind turbines, stall regulation may be a viable alternative for off-grid applications.

An experimental proof-of-concept for damage detection in composite beams using modal analysis has been conducted. The purpose was to demonstrate that damage features can be detected, located, and measured on the surface of a relatively complex thin-wall beam made from composite material. (1) Background: previous work has been limited to the study of simple geometries and materials. (2) Methods: damage detection in the work is based on the accurate measurement of mode shapes and an appropriate design of the detection mesh. Both a method requiring information about the healthy structure and a baseline-free method have been implemented. (3) Results: short crack-type damage features, both longitudinal and transverse, were detected reliably, and the true length of the crack can be estimated from the damage signal. Simultaneous detection of two cracks on the same sample is also possible. (4) This work demonstrates the feasibility of automated damage detection in composite beams using sensor arrays.

Cerebral palsy (CP) is the most common physical disability affecting children, often resulting in reduced quality of life due to challenges with movement control, posture, balance, and increased energy expenditure required to walk. Lower-limb exoskeletons (LLEs) offer a promising alternative to traditional rehabilitation methods, with the potential to improve mobility in children with CP. This review aims to provide an updated overview of mechanical characteristics, control strategies, technological advancements, clinical efficacy, and limitations associated with pediatric LLEs for gait rehabilitation in children with CP. The main objectives were to evaluate the current state of technology, review the clinical outcomes of exoskeleton use, and identify emerging trends and challenges in this field. To achieve this, a comprehensive search was conducted using Scopus and Web of Science databases to identify relevant recent studies published from 2020 onward. A total of 11 studies were included based on pre-defined inclusion and exclusion criteria. The findings suggest that pediatric exoskeletons have shown promise in improving gait parameters, such aswalking speed and joint kinematics while reducing the metabolic cost in children with CP. Despite these positive outcomes, challenges remain regarding device customization, long-term adherence, and integration into clinical practice. The review underscores the potential of pediatric exoskeletons to significantly improve mobility and quality of life in children with CP but also emphasizes the need for further research to optimize device design, long-term outcomes, and standardized guidelines and protocols to conduct and evaluate clinical trials. These findings have important implications for clinicians, researchers, and developers who seek to advance the field of pediatric rehabilitation technologies.

A new method is described, allowing to locate and also measure the length and orientation of crack-type damage features in thin-walled composite beams (TWCB), a capability not previously reported. The method is based on a modal-analysis technique and is shown to work on a hollow composite beam, going beyond previous work limited to simple beams and plates. The method is shown to be capable to function down to signal-to-noise ratios (SNR) of about 15, corresponding to far noisier conditions than in most previous work. This capability is achieved by a combination of wavelet de-noising and the use of a 2D Continuous Wavelet Transform (CWT), applied to two modal analysis metrics, COMAC and Mode Shape Differences (MSD). The length and orientation of the crack can be determined accurately using a 2D curve fitting approach. Using either COMAC or MSD produces reliable results, but MSD is found to be somewhat more noise-tolerant. The new method is believed to be useful for the measurement of damage features in a variety of thin-walled composite beams such as aircraft wings and wind turbine blades, among others.