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Monograph “Adaptive Feedback Control System for Reduction of Vibroacoustic Emission" (Ł. Nowak, IPPT Reports 2/2014).
The aim of the present study is to introduce the possibilities of modifying vibrations of a thin plate structure with arbitrary boundary conditions using the developed, original active feedback control system in such manner that the amplitude of the acoustic pressure field generated by the plate is minimized in a selected point of the ambient space. Theoretical investigations on the phenomena underlying the processes of detection and excitation of vibrations of thin plate structures using piezoelectric transducers are presented. An original algorithm for computation of the free-field acoustic radiation characteristics of vibrating plate structures with arbitrary boundary conditions has been developed and implemented. The algorithm provides a significant reduction of the required computational time and cost. Novel optimal control and adaptation algorithms for determining optimal feedback gain values, for which the amplitude of acoustic pressure is minimized in a given point of the ambient space surrounding the controlled structure, have also been developed. The active vibroacoustic control system used in experimental investigations has been designed and constructed in accordance with an original concept, with separated, independent analogue feedback paths. The results of experiments carried out in an anechoic chamber showed that under the assumed conditions it is possible to obtain significant levels of reduction of noise emitted by the controlled plate structure, excited to vibrate by an external force. Contents: | |
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Monograph “Vibration Control with Smart Materials" (Cz. Bajer, B. Dyniewicz, D. Pisarski, J. M. Bajkowski, seria: Biblioteka Mechaniki Stosowanej).
Rapid technological progress in mechanics, robotics, civil and mechanical engineering entails the reduction of the level of harmful vibrations. The theoretical basis of possible strategies was derived many years ago by employing the theories of control and vibration. However, the possibility of their practical use is not sufficiently investigated yet. Control of smart material parameters can significantly enhance the performance of semi-active damping of vibrating structural elements. This technique may be used in various ways. Good examples of parametric control is to take into account changes of friction, viscosity or damping. In recent years, magnetorheological shock absorbers became popular, although the fluid contained therein also has disadvantages. Alternatively, elastomers with controlled properties or granular materials controlled by vacuum are used. The book is addressed to graduate students, scientists and engineers. It shows the possible range of the control properties of structures in civil and mechanical engineering. The reader will find a theoretical basis on structural vibrations of bending or torsion elements, including those subjected to a load moving, strategies of semi-active optimal control and examples of their use in real engineering structures. Presented analytical considerations are validated by numerical simulations and experiments. Contents: | |
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Monograph „Systemy Uwalniania Leków oparte na Nanowłóknach" (P. Nakielski, IPPT Reports 1/2015).
In this work the task of preparation of drug release system based on the biodegradable polymeric materials made from nanofibers obtained by electrospinning is presented. The main goal of this work was to create an active dressing for the use in neurosurgery. The work includes experimental and numerical analysis of the release process and transport of the drug to the typical buffer fluid and tissue simulator aimed at finding the optimal conditions to control in time and space the drug concentration distribution. The drug release in proposed mathematical model was described by the adsorption-desorption equation while transport in the porous material by the diffusion equation. Presented analysis of nanofibrous material parameters affecting drug release rate, the mathematical description of the process of local drug release from polymeric materials as well as the transport of active substances in the body, in particular in brain tissue, enabled the construction of a numerical model allowing a parametric evaluation of geometric factors, structure of the material, the drug encapsulation in the fibers, as well as the properties of nanofibers on the drug release profiles. Conducted in collaboration with the Mossakowski Medical Research Centre PAS neurosurgeries performed on an animal model confirmed positive impact of nanofibrous materials on the process of regeneration of nerve tissue, preventing at the same time improper process of tissue scarring. Contents: |
