Search results for "tractor"

Deterministic chaos and the first positive Lyapunov exponent: a nonlinear analysis of the human electroencephalogram during sleep

1993

Under selected conditions, nonlinear dynamical systems, which can be described by deterministic models, are able to generate so-called deterministic chaos. In this case the dynamics show a sensitive dependence on initial conditions, which means that different states of a system, being arbitrarily close initially, will become macroscopically separated for sufficiently long times. In this sense, the unpredictability of the EEG might be a basic phenomenon of its chaotic character. Recent investigations of the dimensionality of EEG attractors in phase space have led to the assumption that the EEG can be regarded as a deterministic process which should not be mistaken for simple noise. The calcu…

Endoscope-assisted Brain Surgery: Part 2—Analysis of 380 Procedures

1998

Objectives Microsurgical techniques and instruments that help to reduce intraoperative retraction of normal intracranial neuronal and vascular structures contribute to improved postoperative results. To achieve sufficient control of the operating field without retraction of neurovascular components, the resection of dura and bone edges is frequently required, which, on the other hand, increases operating time and operation-related trauma. The use of endoscopes may help to reduce retraction and, at the same time, may help to avoid additional dura and bone resection. The aim of this study is to describe the principles on which the technique of endoscope-assisted brain surgery is based, to giv…

CLINICAL ROLE OF GASLESS LAPAROSCOPIC ADRENALECTOMY

2009

BACKGROUND: Several studies have demonstrated that the pneumoperitoneum (PNP) may have several hemodynamic, metabolic, neurologic, and humoral effects; in a limited number of patients, these effects represent a contraindication to the use of the PNP in the presence of glaucoma, cardiovascular insufficiency, advanced chronic obstructive bronchitis, and neurologic disease. PATIENTS AND METHODS: Between May 2002 and July 2008, we performed 9 laparoscopic gasless adrenalectomies in 8 patients (5 male and 3 female): 4 left, 3 right, and 1 bilateral, treated in 2 different operations. Mean age was 54.8 years (range: 34 to 76 y). Preoperative diagnosis was Cushing in 5 cases, pheochromocytoma in 1…

Design, Manufacturing, and Strength Test of a 4-post ROPS Fitted on a Very Low-Profile Tractor (TRACLAS Project)

2022

To improve the safety level when agricultural tractors work on slope under canopy, INAIL (the Italian National Institute for Insurance against Accidents at Work) funded a research project, named TRACLAS, devoted to set-up a prototype of low-profile compact tractor, not exceeding 1.60 m overall height, equipped with a 4-post ROPS (RollOver Protective Structure). After the complete set-up of the prototype, some field and lab tests were carried out to compare its performance with those of some comparable tractor models already on the market, used in vineyards, orchards and greenhouses. A basic step of the TRACLAS project was the execution of the strength test of the customized 4-post frame (th…

Attractors/Basin of Attraction

2020

It is a controversial issue to decide who first coined the term “attractor”. According to Peter Tsatsanis, the editor of the English version of Prédire n’est pas expliquer, it was René Thom who first introduced such a term. It is necessary, however, to remember that Thom thought that it was first introduced by the American mathe- matician Steven Smale, “although Smale says it was Thom that coined the neolo- gism “attractor”“(Tsatsanis 2010: 63–64 n. 20). From this point of view, Bob Williams expressed a more cautious opinion by saying that “the word “attractor” was invented by these guys, Thom and Smale” (Cucker and Wong 2000: 183). But other mathematicians are of the opinion that the term …

From Topology to Quasi-Topology. The Complexity of the Notional Domain

2016

This article examines a fundamental metalinguistic construction of the theory of enunciative operations: the notional domain. In particular, we try to explain some elementary topological concepts on which this construction is based and we try to show the key role they play in the description of some basic linguistic operations.

Counterexamples to the Kalman Conjectures

2018

In the paper counterexamples to the Kalman conjecture with smooth nonlinearity basing on the Fitts system, that are periodic solution or hidden chaotic attractor are presented. It is shown, that despite the fact that Kalman’s conjecture (as well as Aizerman’s) turned out to be incorrect in the case of n > 3, it had a huge impact on the theory of absolute stability, namely, the selection of the class of nonlinear systems whose stability can be studied with linear methods. peerReviewed

IWCFTA2012 Keynote Speech I - Hidden attractors in dynamical systems: From hidden oscillation in Hilbert-Kolmogorov, Aizerman and Kalman problems to …

2012

Summary form only given. In this survey an attempt is made to reflect the current trends in the synthesis of analytical and numerical methods to develop efficient analytical-numerical methods, based on harmonic linearization, applied bifurcation theory and numerical methods, for searching hidden oscillations.

Attracteurs et bifurcations en dynamique holomorphe

2019

Buckling and nonlinear dynamics of elastically coupled double-beam systems

2016

Abstract This paper deals with damped transverse vibrations of elastically coupled double-beam system under even compressive axial loading. Each beam is assumed to be elastic, extensible and supported at the ends. The related stationary problem is proved to admit both unimodal (only one eigenfunction is involved) and bimodal (two eigenfunctions are involved) buckled solutions, and their number depends on structural parameters and applied axial loads. The occurrence of a so complex structure of the steady states motivates a global analysis of the longtime dynamics. In this regard, we are able to prove the existence of a global regular attractor of solutions. When a finite set of stationary s…