Search results for "Tractors"
showing 4 items of 34 documents
EXPERIMENTAL INVESTIGATION OF DILUTE SOLID-LIQUID SUSPENSION IN AN UNBAFFLED STIRRED VESSELS BY A NOVEL PULSED LASER BASED IMAGE ANALYSIS TECHNIQUE
2009
The availability of experimental information on solid distribution inside stirred tanks is a topic of great importance in several industrial applications. The measurement of solid particle distribution in turbulent multiphase flow is not simple and the development of suitable measurement techniques is still in progress. In this work a novel non-intrusive technique for measuring particle concentration fields in solid-liquid systems is employed. The technique makes use of a laser sheet, a high sensitivity digital camera for image acquisition and a Matlab procedure for post-processing the acquired images. Experimental data are here obtained for the case of an unbaffled stirred tank. Stable tor…
Minimally Invasive Surgery for Decompression in Chiari I Malformation
2019
Chiari malformations (CMs) includes different pathologies sharing common anatomic deformities of the brainstem and cerebellum. CM type I was originally introduced by Hans Chiari and described as an “elongation of the tonsils and the medial parts of the inferior lobes of the cerebellum into cone-shaped projections which accompany the medulla oblongata into the spinal canal.” The prevalence of CM has been estimated to be between 0.1% and 0.5%, but it is possible that higher rates will be identified since the increasing the use of magnetic resonance imaging (MRI) in common clinical practice. Clinical studies have shown an equal prevalence in both sexes without particular ethnic or geographic d…
The use of a new kind of low profile retractor for arteriovenous fistula procedure simplifies and speeds up the intervention
2009
Purpose The aim of this study was to demonstrate the effectiveness of a new kind of disposable surgical retractor in arteriovenous fistula (AVF) procedures in order to achieve an easier, faster and safer surgical intervention. Methods Between January and June 2008, 22 AVF procedures were performed using the 3PAWS ReeTrakttrade; (Insightra Inc. - Irvine, Ca., USA) a self-retaining, low profile retractor. An equivalent patient sample, in which an AVF was performed using conventional retraction devices, was considered for comparison of the intra- and post-operative results. Results In all of the 22 AVF procedures performed, the ReeTrakt™ system has simplified the performance of the surgical te…
Coexistence of hidden attractors and multistability in counterexamples to the Kalman conjecture
2019
The Aizerman and Kalman conjectures played an important role in the theory of global stability for control systems and set two directions for its further development – the search and formulation of sufficient stability conditions, as well as the construction of counterexamples for these conjectures. From the computational perspective the latter problem is nontrivial, since the oscillations in counterexamples are hidden, i.e. their basin of attraction does not intersect with a small neighborhood of an equilibrium. Numerical calculation of initial data of such oscillations for their visualization is a challenging problem. Up to now all known counterexamples to the Kalman conjecture were const…