Bhola Thapa

Introduction: Pediatric prosthetic knee joints must be appropriately scaled from adult designs to ensure proper gait biomechanics. However, direct dimensional scaling without considering the biomechanical implications may lead to functional discrepancies. This study aimed to evaluate whether using a linear scaling factor can effectively adapt a knee for pediatric use. The study assessed whether such an approach yields a viable pediatric prosthetic knee joint by applying a fixed scaling factor and analyzing the resultant knee geometry. Methods: The linear scaling factor was determined based on the pylon tube diameter, a key constraint in compact pediatric knee design. Given a pediatric pylon diameter of 22 mm, the length of the tibial link was set to 22 mm, yielding a scaling factor of 0.6875 when compared to the adult-sized knee. This scaling factor was used to determine the dimensions of the pediatric four-bar (scaled) knee joint. Static geometric analysis was conducted using GeoGebra^® to model the lower-body segment lengths. The knee joint’s performance was evaluated based on stance and swing phase parameters. These metrics were compared between the scaled knee and a commercial pediatric knee. Results: The geometric analysis revealed that while using the linear scaling factor maintained proportional relationships, certain biomechanical parameters deviated from the expected pediatric norms. The scaled knee achieved a toe clearance of 13.5 mm compared to 19.7 mm in the commercial design and demonstrated a swing-phase heel clearance of 11.6 mm versus 13.3 mm, maintaining negative x/y ratios at heel contact and showing significant stability in push-off moments, while the stance flexion angle remained within an acceptable range. The heel contact and push-off ratios (x/y) were found to be comparable, with the scaled model achieving values of −1.21 and −0.59, respectively. The stance flexion angle measured 10.6°, closely aligning with the commercial reference. Conclusions: Using a linear scaling factor provides a straightforward method for adapting adult prosthetic knee designs to pediatric use. However, deviations in key biomechanical parameters indicate that further experimental study may be required to validate the applicability of the scaled knee joint for pediatric users. Future work should explore dynamic simulations and experimental validations to refine the design further and ensure optimal gait performance.

Hydro turbines are prone to failure and the detection of fault in turbine is essential to ensure the reliability of power plant. This study investigates vibrational signals in a fault-induced Francis turbine using an experimental test setup to identify the trends that could be helpful in diagnosis of turbine faults. By analyzing the vibrational signal, the study aims to correlate the turbine's dynamic behavior. Faults in the turbine have been introduced by adding masses to the blades, and the experimental tests are conducted under two different conditions: dry and wet testing conditions for both normal and faulty turbine blades. The turbine's operating condition is determined with the help of pressure, flow, and RPM sensors. The turbine's speed is varied using a variable frequency drive. For the acquisition of vibration signals, the NI-LabVIEW system is employed along with a uniaxial vibration sensor located at the turbine bearing. The obtained vibration data are analyzed using the Fast Fourier Transform (FFT) algorithm and wavelet transform algorithm to identify frequency-domain characteristics. While studying and comparing the fundamental frequency of the turbine shaft, it is found that turbine faults can either increase or decrease the amplitude of the resonant peak frequency of the system, but the amplitude at other frequencies remains almost unaffected.