Search results for "VIBRATION"
showing 10 items of 823 documents
Optical Fibre, Local Measurement Systems For Ships
1987
Modern ships are more and more fully equipped with auxilliary control and supervising sys-tems. These systems, in turn, are more and more frequently built with the aid of fibre optics. Fibre optics ensures proper reliability of such a system in a harsh marine environment. This environment includes: marine climate containing salt spray, mechanical vibrations and shocks, electromagnetic and magnetic interferences, changing temperatures etc. All of these harmful reactions may influence the system /worst case marine environment/ during a single sailing cruise. We will consider here the worst case environment for a marine-grade fibre optic system.
Experimental Study of Vibrations in Face Milling Cutting
2014
Abstract The present paper consists in a comparison of vibrations measured during face milling cutting with two constructive variants of milling cutters (one with classic insert clamping and other with a quick insert adjustment mechanism). The goal of the study is to determine if the new clamping mechanism of the inserts has a similar behaviour with the classic one and can withstand milling conditions without introducing additional vibrations in the system
Monitoring and Diagnosis of Failures in Squirrel-Cage Induction Motors Due to Cracked or Broken Bars
2011
In this paper three diagnostic procedures, based on on the vibration, current and instantaneous power monitoring for the detection and monitoring of incipient faults as cracks or bar breaks on squirrel cage motors are briefly reminded. The experimental investigations, carried out at the SDESLab (Sustainable Development Energy Savings Laboratory) of the University of Palermo in order to underline merits and drawbacks of the methods applied to the same die cast squirrel cage induction motor, are presented. The results of the investigations confirmed the effectiveness of the diagnostic procedures here considered.
Control Design Methodologies for Vibration Mitigation on Wind Turbine Systems
2011
Published version of a chapter in the book: Vibration Analysis and Control - New Trends and Developments. Also available from the publisher at: http://www.intechopen.com/source/pdfs/17693/InTech-Control_design_methodologies_for_vibration_mitigation_on_wind_turbine_systems.pdf. OA
A convex optimization approach for vibration control of base isolated structures with limited wireless communication capacity
2010
The problem of H ∞ control design for vibration reduction of a base isolated structure with limited wireless communication capacity is studied in this paper. The network under consideration is subjected to measurement quantization, signal transmission delay, and data packet dropout, which appear typically in a network environment. Based on Lyapunov-Krasovskii functional (LKF) theory, some delay-range-dependent conditions are established for the existence of desired controllers such that the resulting closed-loop system is asymptotically stable and its performance is kept within a prescribed level. Finally, some simulation results are given to illustrate the effectiveness of our method.
Work-Related Stress from Whole-Body Vibration
1986
During the last 10 years, many field experiments have been carried out in various places of work. Vibration has been measured in buildings, in vehicles, and on ships. These data are currently being compiled (Dupuis and Hartung 1982) to be fed into the vibration data bank at the BIA.
Analysis of EMI Shielding Effectiveness for plastic fiber composites in the 5G sub-6 GHz band
2021
The study and modeling of EMC are becoming more critical than ever due to the ubiquitous presence of electronic circuits in all aspects of our lives. Specifically, it is crucial to extend these studies to the new frequencies that, in a few years, will be a reality in modern telecommunications systems, such as 5G and its derived technologies. A specific critical field where the proper EMI shielding has been ensured to avoid EMC problems is the electric autonomous vehicles (EAVs). The huge number of electronics systems in new vehicles will dramatically extend the demands on the EMI shielding solutions used to attenuate the radiated emissions that could affect circuits in the vehicle. Metals o…
Femtometer accuracy EXAFS measurements: Isotopic effect in the first, second and third coordination shells of germanium
2009
The analysis of the EXAFS signals from 70Ge and 76Ge has evidenced the low-temperature effect of isotopic mass difference on the amplitude of relative atomic vibrations. This effect is reflected in the difference of the Debye-Waller factors of the first three coordination shells, and on the difference of nearest-neighbour average interatomic distances, evaluated with femtometer accuracy. The experimental results are in agreement with theoretical expectations.
Creep Modeling with Time-Dependent Damping Parameters in Piezoelectric Actuators
2019
This paper develops a creep model based on the Kelvin-Voigt model with time varying damping parameters. In the piezoelectric actuators, the creep phenomenon is an important issue in precise positioning applications as well as the hysteresis property. It is well-known that the creep effect can be represented by a series connection of a number of Kelvin-Voigt elements as a viscoelastic model. In the motion for the continuous stepwise positioning, however, the creep shape is different for each response. Since the phenomenon can be captured as temporal creep relaxation, time-dependent damping parameters are introduced to improve the reproducibility of the creep for the various motion. On the ot…
Machine Learning approach towards real time assessment of hand-arm vibration risk
2021
Abstract In industry 4,0, the establishment of an interconnected environment where human operators cooperate with the machines offers the opportunity for substantially improving the ergonomics and safety conditions of the workplace. This topic is discussed in the paper referring to the vibration risk, which is a well-known cause of work-related pathologies. A wearable device has been developed to collect vibration data and to segment the signals obtained in time windows. A machine learning classifier is then proposed to recognize the worker’s activity and to evaluate the exposure to vibration risks. The experimental results demonstrate the feasibility and effectiveness of the methodology pr…