Sinusoidal Phase-Modulated Angle Interferometer for Angular Vibration Measurement

Primary angular vibration calibration devices based on laser interferometers play a crucial role in evaluating the dynamic performance of inertial sensing devices. Here, we propose a sinusoidal phase-modulated angle interferometer (SPMAI) to realize angular vibration measurements over a frequency range of 1–1000 Hz, in which the sinusoidal measurement retro-reflector (SMR) and the phase generation carrier (PGC) demodulation algorithm are adopted to track the dynamic angle variation. A comprehensive theoretical analysis is presented to reveal the relationship between demodulation performance of the SPMAI and several factors, such as phase modulation depth, carrier phase delay and sampling frequency. Both the simulated and experimental results demonstrate that the proposed SPMAI can achieve an angular vibration measurement with amplitude of sub-arcsecond under given parameters. Using the proposed SPMAI, the frequency bandwidth of an interferometric fiber-optic gyroscope (IFOG) is successfully determined to be 848 Hz.

Wood pellets transport with vibrating conveyor: experimental for DEM simulations analysis

This work presents a comprehensive overview of the mechanical-physical parameters of the transport material affecting the vibratory transport. For this purpose, spruce pellets of different lengths, oak rods and spruce crush were tested. The determined parameters were particle size distribution and shape, internal friction, static and dynamic angle of repose. The samples were transported by a patented validation vibrating conveyor. Various settings were used. The results show that by changing the shape, it is possible to reduce friction or resistance as well as energy intensity during transport. It was observed that perfect shapes and lighter particles have lower friction, but a more pronounced bounce. Therefore, it does not form a typical pattern during transport, as in the case of an imperfectly shaped one. There is also included a simulation of the discrete element method. The study shows the possibility of the vibration machine where the material can be conveyed either directionally or sorted.

The influence of degree of loading and load placing on steerability of vehicles

The methodology of research of the influence of the degree of loading, kinematic parameters of movement, and nonlinear power characteristics of elastic elements and shock-absorbers of the suspension system on their steerability on curved sections of the road is developed. The research is based on the equation of kinetostatics of the system of sprung-unsprung part and differential equations that relate the motion of the sprung part of vehicles. Concerning the last, they take into account both loading of a vehicle and nonlinear-elastic characteristics of shock-absorbers. For the case when elastic characteristics of shock-absorbers are described by degree or close to it dependence, the fluctuation of sprung part is described analytically. Their peculiarity is that the frequency and therefore dynamic force of wheels pressure on the bearing surface (road) depends on the amplitude. It is the last value and characteristics of the road surface that determine the main parameters of steerability and stability of the movement of wheeled vehicles along curved sections of the road. Taken together, the mentioned above allowed to obtain the dependence of the critical value of the dynamic angle of rotation of the steered wheels, as a function of the amplitude of longitudinal-angular oscillations, kinematic motion parameters, and the level of loading of a vehicle. It is established: - fluctuation of the sprung part significantly reduce the value of the limiting angle of rotation of the steered wheels along the curved sections of the road; - for the period of acceleration of the vehicle and the closer location of the center of gravity of the cargo transported to the tailgate, the limit value of the dynamic angle of rotation of the steered wheels is less; - the suspension system with the progressive law of change of regenerative force of elastic shock-absorbers in a wider range of change fluctuations amplitude of the suspended part satisfies ergonomic conditions of transportation. The obtained calculated dependencies can simultaneously be basic during the modernization of existing or the creation of new suspension systems in order to improve the main operation characteristics of wheeled vehicles

Occurrence of asymmetries of lower limbs in basic futsal athletes

Futsal is a sport on the rise worldwide, attracting more and more new practitioners and as well as in field soccer, it has undergone changes in recent years, increasingly demanding athletes, becoming a high impact sport, promoting overload, in the short, medium and long term, predisposing to injury to different degrees of the locomotor apparatus. The aim of this study was to analyze lower limbs asymmetries in futsal-based athletes, as well as their relationship to the incidence of injuries. The study was developed with 47 athletes of the basic category, futsal, from a city in the interior of the state of São Paulo, where functional tests were performed with the help of the PHAST application. A pattern of similarity was identified between the muscle groups tested, except for the gluteus muscle, presenting a significant difference. According to the indicators found, the patterns of strength deficit of the middle glutes may trigger, or predispose to, some types of biomechanical lesions whether proximal, in the hip region, or distal, as dysfunctions in the knee joint. When an athlete presents with a weakness of this muscle, ipsilateral femur adduction, increased medial rotation and fall of the pelvis against lateral, promoting increased dynamic angle of the knee, increasing the overload in this joint. Thus, it is concluded that pre-season evaluation is important to identify possible asymmetries, implementing preventive work to correct them, in order to minimize the risks of injuries.