Currently used planar manipulation methods that utilize oscillating surfaces are usually based on asymmetries of time, kinematic, wave, or power types. This paper proposes a method for omnidirectional manipulation of microparticles on a platform subjected to circular motion, where the motion of the particle is achieved and controlled through the asymmetry created by dynamic friction control. The range of angles at which microparticles can be directed, and the average velocity were considered figures of merit. To determine the intrinsic parameters of the system that define the direction and velocity of the particles, a nondimensional mathematical model of the proposed method was developed, and modeling of the manipulation process was carried out. The modeling has shown that it is possible to direct the particle omnidirectionally at any angle over the full 2π range by changing the phase shift between the function governing the circular motion and the dry friction control function. The shape of the trajectory and the average velocity of the particle depend mainly on the width of the dry friction control function. An experimental investigation of omnidirectional manipulation was carried out by implementing the method of dynamic dry friction control. The experiments verified that the asymmetry created by dynamic dry friction control is technically feasible and can be applied for the omnidirectional manipulation of microparticles. The experimental results were consistent with the modeling results and qualitatively confirmed the influence of the control parameters on the motion characteristics predicted by the modeling. The study enriches the classical theories of particle motion on oscillating rigid plates, and it is relevant for the industries that implement various tasks related to assembling, handling, feeding, transporting, or manipulating microparticles.
At present, the noise problem is already widely discussed and identified as a priority to ensure human health and the prevention of occupational diseases. We understand acoustic field management as a targeted use of actions and tools to change field parameters or characteristics. In general, the most effective effects on the fields are the elimination of their generation conditions. In this work the vibration analysis of the recuperators was performed, the limits of the vibration parameters were determined and the correlation between the vibration activity of the device and the sound pressure level in the near environment was determined. After the design of the fan partitions and the airflow excitation of the fans with respect to vibration parameters, it was found that the above mentioned structural changes allowed to reduce the average total weighted sound pressure level in the vicinity by 8%.
This study focuses on the results obtained by the transformation of acoustic energy in the form of vibrations into electrical energy. The vibrations are transmitted from outdoors through a window glass covered with piezoelectric material. Only one side of the window glass is covered with piezoelectric material at certain positions. The paper also presents a mathematical model to describe the transformation of acoustic energy into electrical energy. The results obtained from the numerical experiments are used to determine the dimensions of the piezoelectric film and their optimum positions on the glass for electricity generation. The correct placement of piezoelectric material on the glass generates electrical energy of approximately 10 mV. The use of smart materials in window glass allows the management of acoustic energy.
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