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EN
The use of bone cement in procedures such as vertebroplasty and kyphoplasty can reduce pain and mechanically support the spine. This study aimed to evaluate whether air entrapped within bone cement affected its distribution in a vertebral body model. The study included 3D printed anatomical models of vertebrae together with their internal trabecular structure. Aeration was achieved by mixing the bone cement using three different altered procedures, whilst the control sample was prepared according to the manufacturer’s instructions. The further two samples were prepared by reducing or increasing the number of cycles required to mix the bone cement. A test rig was used to administer the prepared bone cement and introduce it into the vertebral model. Each time the injection was stopped when either the cement started to flow out of the vertebral model or when the entire cement volume was administered. The computer tomography (CT) scanning was performed to evaluate aerification and its influence on the bone cement distribution in each of the patient-specific models. The large number of small pores visible within the cement, especially in the cannula vicinity, indicated that the cement should not be treated as a homogenous liquid. These results suggest that a high level of aerification can influence the further cement distribution.
2
Content available remote Experimental and numerical investigations of pipeline with resonator
EN
This article presents the current state of the art. regarding the use resonators in straight pipes. There is considerable need to control and reduce pressure pulsation in pipelines supplied with pulsating flows. The use of a Helmholz resonator introduces an additional degree of freedom to the analysed dynamic system. Building on previous experimental investigations by the authors, which identified the nonlinear properties of straight pipes supplied with pulsating flows, this study describes an experimental test rig, measurement methods and mechanical analogies for one (1DOF) and two (2DOF) degrees of freedom. The results are presented in the form of a 3D map of amplitude-frequency characteristics, as a function of the resonator volume determined by piston height. The dynamic properties of the described system are presented as amplitude-phase characteristics, based on a comparison of the numerical and experimental results.
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