scholarly journals On the Use of Linear and Nonlinear Controls for Mechanical Systems Subjected to Friction-Induced Vibration

2020 ◽  
Vol 10 (6) ◽  
pp. 2085
Author(s):  
Baptiste Chomette ◽  
Jean-Jacques Sinou
Keyword(s):  
Signal To Noise Ratio ◽  
Physical Phenomenon ◽  
Mechanical Systems ◽  
Industrial Applications ◽  
Control Vector ◽  
Controlled Systems ◽  
Control Gain ◽  
Complete Study ◽  
Linear And Nonlinear ◽  
Friction Induced Vibration

Friction-Induced Vibration and noisE (FIVE) is still a complex and nonlinear physical phenomenon which is characterized by the appearance of instabilities and self-sustained vibrations. This undesirable vibrational phenomenon is encountered in numerous industrial applications and can cause major failures for mechanical systems. One possibility to limit this vibration phenomenon due to the appearance of instabilities is to add a controller on the system. This study proposes to discuss the efficiency but also limitations of an active control design based on full linearization feedback. In order to achieve this goal, a complete study is performed on a phenomenological mechanical system subjected to mono or multi-instabilities in the presence of friction. Transient and self-excited vibrations of the uncontrolled and controlled systems are compared. More specifically, contributions of linear and nonlinear parts in the control vector for different values of friction coefficient are investigated and the influence of the control gain and sensitivity of the controller to the signal-to-noise ratio are undertaken.

EUCOR: An Efficient Unequal Clustering and Optimal Routing in wireless sensor networks for energy conservation

2021 ◽  
pp. 1-9
Author(s):  
C. Jothikumar ◽  
Revathi Venkataraman ◽  
T. Sai Raj ◽  
J. Selvin Paul Peter ◽  
T.Y.J. Nagamalleswari
Keyword(s):  
Objective Function ◽  
Physical Phenomenon ◽  
Minimum Energy ◽  
Cluster Head ◽  
Industrial Applications ◽  
Base Station ◽  
Wireless Sensor ◽  
Unequal Clustering ◽  
Minimum Energy Consumption ◽  
Variable Cluster

Wireless sensor network is a wide network that works as a cutting edge model in industrial applications. The sensor application is mostly used for high security systems that provide safety support to the environment. The sensor system senses the physical phenomenon, processes the input signal and communicates with the base station through its neighbors. Energy is the most important criterion to support a live network for long hours. In the proposed system, the EUCOR (Efficient Unequal Clustering and Optimized Routing) protocol uses the objective function to identify the efficient cluster head with variable cluster size. The computation of the objective function deals with the ant colony approach for minimum energy consumption and the varying size of the cluster in each cycle is calculated based on the competition radius. The system prolongs the lifespan of the nodes by minimizing the utilization of energy in the transmission of packets in the networks when compared with the existing system.

scholarly journals Pneumatic Actuator Controlled by Proportional Valve. Experimental results

2021 ◽  
Vol 286 ◽  
pp. 04010
Author(s):  
Valentin Nicolae Cococi ◽  
Constantin Călinoiu ◽  
Carmen-Anca Safta
Keyword(s):  
Control Valve ◽  
Industrial Applications ◽  
Experimental Results ◽  
Pneumatic Actuator ◽  
Proportional Valve ◽  
Controlled Systems ◽  
Automation Systems ◽  
Simulation Results ◽  
The Mathematical Model ◽  
Fire Ignition

In nowadays the pneumatic controlled systems are widely used in industrial applications where valves must be operated, where there is a fire ignition risk, or in different automation systems where a positioning action is desired. The paper presents the experimental results of a pneumatic actuator controlled by a proportional control valve. The goal of the paper is to compare the experimental results with the numerical simulation results and to improve the mathematical model associated with the experiment.

Wind Tunnel Balance Design— The Simultaneous Measurement of Forces and Moments

1954 ◽  
Vol 58 (518) ◽  
pp. 141-143
Author(s):  
C. G. Saunders
Keyword(s):  
Wind Tunnel ◽  
Simultaneous Measurement ◽  
Mechanical Systems ◽  
Industrial Applications ◽  
Component Separation ◽  
Measuring Instrument ◽  
Mechanical Method ◽  
Balance Design ◽  
Wind Tunnel Balance ◽  
Simultaneous Measuring

An electro-mechanical method of simultaneous component separation is suggested as an alternative to mechanical systems. Based on the commonly used weighbeam, employing a motor driven leadscrew, poise weight, selsyn repeater circuit and counter, component separation is proposed by means of the selsyn differential circuit.The use of the selsyn motor as a direct or differential telemeter mechanism is well known, and as such, has many industrial applications. Such use, applied to the aerodynamic balance, offers the advantage of avoiding many of the difficulties associated with design and in particular, the construction of a mechanically independent and simultaneous measuring instrument.

scholarly journals Non Smooth Contact Dynamics Approach for Mechanical Systems Subjected to Friction-Induced Vibration

Lubricants ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 59 ◽  
Author(s):  
Jean-Jacques Sinou ◽  
Olivier Chiello ◽  
Lucien Charroyer
Keyword(s):  
Mechanical Systems ◽  
Mathematical Community ◽  
Contact Dynamics ◽  
Strong Impact ◽  
Brake Squeal ◽  
Excited Vibration ◽  
Smooth Contact ◽  
Frictional Interface ◽  
The Stability ◽  
Friction Induced Vibration

The modeling of contact is one of the main features of contact dynamics in the context of friction-induced vibrations. It can have a strong impact on the numerical results and consequently on the design choices during the optimization or specification of industrial mechanical systems. This is particularly the case for scientific studies interested in brake squeal. The objective of the paper is to recall and to promote developments concerning the use of non smooth contact dynamics approach for numerical simulations based on finite element method. The specific problem of the prediction of self-excited vibration in the context of brake squeal is discussed. In order to illustrate the potential benefit for the mechanical community of using formulations and theoretical developments from the mathematical community, the stability analysis and the estimation of nonlinear vibrations of a brake system with multiple frictional interface is investigated.

scholarly journals A 77-GHz Six-Port Sensor for Accurate Near-Field Displacement and Doppler Measurements

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2565 ◽  
Author(s):  
Homa Arab ◽  
Steven Dufour ◽  
Emilia Moldovan ◽  
Cevdet Akyel ◽  
Serioja Tatu
Keyword(s):  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
Industrial Applications ◽  
High Signal ◽  
Millimetre Wave ◽  
Sensing Applications ◽  
Radar Sensing ◽  
Cw Radar ◽  
77 Ghz

A continuous-wave (CW) radar sensor design based on a millimetre-wave six-port interferometer is proposed. A complete sensor prototype is conceived of, fabricated and measured at 77 GHz for short-range professional and industrial applications. This sensor is designed to measure distances and Doppler frequencies with high accuracy, at a reasonable cost. Accurate phase measurements are also performed using the six-port technology, which makes it a promising candidate for CW radar sensing applications. Advances in the performance and functionality of six-port sensors are surveyed to highlight recent progress in this area. These include improvements in design, low power consumption, high signal to noise ratio, compactness, robustness and simplicity in realization. Given the fact that they are easy to fabricate, due to the lack of active circuits and being highly accurate, it is expected that six-port sensors will significantly contribute to the development of human tracking devices and industrial sensors in the near future. The entire circuit prototype, including the transmitter, the receiver antenna, the six-port interferometer and the four power detectors have been integrated on a die. The circuit is fabricated using a hybrid integrated technology on a 127-μm ceramic substrate with a relative permittivity of εr=9.8. Calibrated tuning forks are used to assess the performance of the six-port sensor experimentally for various frequencies.

scholarly journals Linear and Nonlinear Schemes Applied to Pitch Control of Wind Turbines

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Hua Geng ◽  
Geng Yang
Keyword(s):  
Controller Design ◽  
Industrial Applications ◽  
Pitch Control ◽  
Advantages And Disadvantages ◽  
Wind Energy Conversion Systems ◽  
Energy Conversion Systems ◽  
Linear And Nonlinear ◽  
Nonlinear Schemes ◽  
Nonlinear Feature ◽  
Digital Processor

Linear controllers have been employed in industrial applications for many years, but sometimes they are noneffective on the system with nonlinear characteristics. This paper discusses the structure, performance, implementation cost, advantages, and disadvantages of different linear and nonlinear schemes applied to the pitch control of the wind energy conversion systems (WECSs). The linear controller has the simplest structure and is easily understood by the engineers and thus is widely accepted by the industry. In contrast, nonlinear schemes are more complicated, but they can provide better performance. Although nonlinear algorithms can be implemented in a powerful digital processor nowadays, they need time to be accepted by the industry and their reliability needs to be verified in the commercial products. More information about the system nonlinear feature is helpful to simplify the controller design. However, nonlinear schemes independent of the system model are more robust to the uncertainties or deviations of the system parameters.

Systems Stability Using Weight Functions Method

2005 ◽  
Author(s):  
Ion Stroe ◽  
Dumitru I. Caruntu
Keyword(s):  
Classical Method ◽  
Liapunov Function ◽  
Weight Functions ◽  
Solution Stability ◽  
First Order ◽  
Controlled Systems ◽  
Linear And Nonlinear ◽  
Function Finding ◽  
Linear And Nonlinear Systems ◽  
First Order Differential Equations

A new method for systems stability analysis is presented. This method is called weight functions method and it replaces the problem of Liapunov function finding with a problem of finding a number of functions (weight functions) equal to the number of first order differential equations describing the system. It is known that there are not general methods for finding Liapunov functions. The weight functions method is simpler than the classical method since one function at a time has to found. This method’s conditions of solution stability for linear and nonlinear systems are presented. Applications such as Lurie-Postnikov problem and controlled systems stability are presented as well.

Unusual Fast Evaporation From Nanoholes

2012 ◽  
Author(s):  
Zhi Huang ◽  
Yuanchen Hu ◽  
Kang Liu ◽  
Xuejiao Hu
Keyword(s):  
Water Surface ◽  
Evaporation Rate ◽  
Physical Phenomenon ◽  
Gravimetric Method ◽  
Industrial Applications ◽  
Water Evaporation ◽  
Good Prediction ◽  
Confined Space ◽  
Affecting Factors ◽  
Air Conditioning Systems

Water evaporation is an important physical phenomenon that occurs in nature and several industrial applications such as food drying processes, cooling in air-conditioning systems and desalination. In all these systems, it is necessary to have a good prediction and control of evaporation rate as a function of various system parameters. Attempts to understand the affecting factors have mostly focus on the flow rates of gas or water streams, relative humidity of the air, presence of dissolved or suspended material in the water, temperatures of the air and water streams. However, as water surface partially covered (less surface area) is generally thought to have lower evaporation rate, little notice has ever put on it. Here we consider the evaporation case of water surface covered with nano-through-hole lid (NHL) of which the radius size is nearly equal to the average free path of the vapor. Using a gravimetric method, we experimentally measured the evaporation rate of water at the orifice of the nano-holes. The results indicate that the evaporation rate is 1–6 times faster than the non-sheltered water surface with the same liquid area. Moreover, with the porosity of the lid decreasing, the evaporation rate per unit area increases. A theoretical model is developed for this novel phenomenon from the view of molecular dynamics during evaporation and vapor diffusion. We envision that this finding may have new inspirations on phase change phenomenon in nano-confined space and put forward one new way for promoting evaporation of liquid.

Study the Structure of Three Dimensional Oblique Shock Waves Over Conical Rotor-Vane Surfaces

2005 ◽  
Author(s):  
Khaled Alhussan
Keyword(s):  
Shock Waves ◽  
Flow Structure ◽  
Numerical Technique ◽  
Physical Phenomenon ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Oblique Shock ◽  
Complex Flow ◽  
Compression And Expansion ◽  
Contour Plots

This paper will explain the numerical analysis and the mapping of the flow in a confined region. In this paper some characteristics of non-steady, compressible, flow are explored, including compression and expansion wave interactions and creation. The results will show a promising achievement, first, to understand the flow structure inside a supersonic confined region, second, to use this knowledge to interpolate the numerical results in order to achieve a design methodology that will benefit the industrial applications for example in turbomachinery. Results including contour plots of static pressure, total pressure, and Mach number will show the structure of oblique shock waves in a complex three-dimensional conical surface. A CFD analysis enables one to understand the complex flow structure inside this confined region. Through this computational analysis, a better interpretation of the physical phenomenon of the three dimensional rotting oblique shock waves can be achieved. It is essential to evaluate the ability of numerical technique that can solve problems in which compression and expansion waves occur. In particular it is necessary to understand the details of developing a mesh that will allow resolution of some discontinuities in similar flow.

Damping Effect in Fluid-Structure Interaction: Application to Slamming Problem

2003 ◽  
Author(s):  
N. Aquelet ◽  
M. Souli
Keyword(s):  
High Pressure ◽  
Physical Phenomenon ◽  
Fluid Structure Interaction ◽  
Underwater Explosion ◽  
Industrial Applications ◽  
Damping Factor ◽  
Local Pressure ◽  
Shipbuilding Industry ◽  
Fluid Structure ◽  
Structure Interaction

During a high velocity impact of a structure on an incompressible fluid, impulse loads with high pressure peaks occur. This physical phenomenon called ‘slamming’ is a concern in the shipbuilding industry because of the possibility of hull damage. Shipbuilding companies are carrying out several studies on the slamming modeling using FEM software. This paper presents the prediction of the local high pressure load on a wedge striking a free surface. The fluid-structure interaction is simulated by a fluid-structure coupling algorithm. This method of coupling, which makes it possible to transmit the efforts in pressure from the Eulerian grid to the Lagrangian grid and vice versa, is a relatively recent algorithmic development. It was successfully used in many scientific and industrial applications: the modeling of the bird strike on the fuselage of a Jet for the Boeing Corporation, underwater explosion shaking the oil platforms, and airbag simulation in automotive industry... Predicting the local pressure peak on the structure requires an accurate fluid-structure interaction algorithm. Thus, some penalty coupling enhancements make the slamming modeling possible. The main improvement is a numerical damping factor which permits to smoothing of the pressure signal.

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