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Vibration reduction assessment of layered acoustic metamaterial

Świrk Patrycja, Żyłka Wojciech, Leniowska Lucyna, Grochowina Marcin

Vibrations in Physical Systems

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2022

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Vol. 33, nr 2

art. no. 2022221

EN

Acoustic meta-materials offer an approach to reducing the vibration and noise transmission through layered panels. In this paper, the investigation of constructed meta-material for reduction of low-frequency vibration and noise is a major concern. The key concept underlying this approach is to construct the metamaterial as a highly-distributed system of tuned point masses that introduce instead of low resonance frequency one or more bands of higher frequency. They can be then successfully damped with passive methods. Using the modes method, a metamaterial system with distributed point masses integrated into the honeycomb core was designed to be a representative layered panel. To determine the dynamic response of the global sandwich panel, the metamaterial system was tested for 70 Hz and 120 Hz excitation. The obtained results confirm the possibility of tuning the considered layered meta-material to the excitation frequency and shifting low frequencies towards higher frequencies.

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Dialysis therapies: Investigation of transport and regulatory processes using mathematical modelling

Pstras Leszek, Stachowska-Pietka Joanna, Debowska Malgorzata, Pietribiasi Mauro, Poleszczuk Jan, Waniewski Jacek

Biocybernetics and Biomedical Engineering

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2022

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Vol. 42, no. 1

60--78

EN

Haemodialysis (HD) and peritoneal dialysis (PD) are the main kidney replacement therapies for patients with end-stage renal disease. Both of these life-sustaining therapies replace the key functions of the failing kidneys, i.e. the removal of the excess body water and waste products of metabolism as well as the restoration of fluid-electrolyte and acid-base balance. The dialysis-induced multi-scale transport and regulatory processes are complex and difficult to analyse or predict without the use of mathematical and computational models. Here, following a brief introduction to renal replacement therapies, we present an overview of the most important aspects and challenges of HD and PD, indicating the types and examples of mathematical models that are used to study or optimize these therapies. We discuss various compartmental models used for the study of intra- and interdialytic fluid and solute kinetics as well as distributed models of water and solute transport taking place across the peritoneal tissue or in the dialyzer. We also discuss models related to blood volume changes and cardiovascular stability during HD, including models of the thermal balance, likely related to intradialytic hypotension. A short overview of models of acid-base equilibration during HD and mineral metabolism in dialysis patients is also provided, along with a brief outline of models related to blood flow in arteriovenous fistulas and cardiovascular adaptations following the fistula creation. Finally, we discuss the model-based methods of assessment of dialysis adequacy in both HD and PD.

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Distributed modeling of osmotic fluid flow during single exchange with hypertonic glucose solution

Stachowska-Piętka J., Waniewski J.

Biocybernetics and Biomedical Engineering

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2011

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Vol. 31, no. 1

39-50

EN

The aim of the study was to model fluid and solute peritoneal transport inside the tissue together with the kinetics in peritoneal cavity during single exchange with hypertonic glucose 3.86% solution. The distributed model of osmotic flow and glucose transport was formulated and applied for computer simulations assuming 1 cm width of tissue layer. The simulated kinetics of intraperitoneal volume and glucose concentration were in good agreement with clinical data. The predicted intratissue profiles of glucose concentration and hydrostatic pressure of the interstitial fluid demonstrated a restricted penetration of glucose (0.1 cm) and water (0.25 cm) into the interstitium at the end of dwell time, in agreement with animal data. The proposed model was able to describe correctly the basic kinetics of peritoneal dialysis as investigated in clinical studies and intratissue profiles known from animal studies.