linear oscillation
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2021 ◽  
pp. 88-96
Author(s):  
Alexey Smirnov ◽  
Boris Smolnikov

This article is devoted to the study of controlled movements of spatial double pendulum with non-parallel cylindrical joints axes. The collinear control is used to swinging of the system by feedback. The most important property of collinear control is the ability of increasing system oscillations only on one oscillation mode. A modification of the collinear control law with variable gain depending on the energy level is investigated. It allows to control the system motions more flexible than in the case of constant gain. As a result, it is possible to observe a smooth transition from a linear oscillation mode to a nonlinear one with a gradual output to a steady oscillation motion with a given energy level. The obtained results are clearly illustrated by graph dependencies that demonstrate the swinging of the system on one oscillation mode from small to finite amplitudes.


2021 ◽  
Vol 13 (9) ◽  
pp. 1821
Author(s):  
Binbin Zhou ◽  
Xiangyang Qi ◽  
Jiahuan Zhang ◽  
Heng Zhang

Ship targets are high-value military and civilian targets with broad application prospects. However, the precise focusing of ships is still a difficult issue because of their complicated six-degree-of-freedom motions on the sea surface. This paper focused on investigating the effect of ship six-degree-of-freedom oscillation on Synthetic Aperture Radar imaging. Firstly, based on the six-degree-of-freedom motions, the accurate range models for ship linear oscillation and angular oscillation were built, and the superiority was verified by comparing them with the models described in published literature. Secondly, we used the Taylor formula and Bessel function to expand the phase error introduced by ship oscillation, then their effects on imaging were further analyzed. Finally, based on the measured ship attitude data, we generated the semi-physical echoes of the oscillatory ship to validate the analysis throughout this article. Based on the proposed range model, we also made some tentative on the phase compensation method by fitting ship attitude angles with multiple sinusoidal functions.


2021 ◽  
Vol 264 ◽  
pp. 04066
Author(s):  
Farkhod Matmurodov ◽  
Dilafruz Ermatova

The article contains generalized systems of equations describing the vertical and longitudinal-angular vibrations of the main parts of the tractor with the mathematical model of the hierarchical vertical linear oscillation of the tractor, the irregularities of the roads, taking into account the rigidity and damping. It includes systems: equations describing the vertical vibrations of the skeleton over the propellers of a tractor on an uneven road; equations describing the vertical vibrations of the cab of the rear of the tractor, taking into account the walking of the tractor on uneven roads. Equation systems have also been compiled that describe the vertical oscillations of the uppermost hierarchical link - the seat of the tractor operator, taking into account the walking of the tractor on an uneven road. The use of this original mathematical model will make it possible to find random unwanted oscillations of the new designed machine design. It will help to optimize their geometric and dynamic parameters.


Lubricants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 5
Author(s):  
Raj Shah ◽  
Rui Chen ◽  
Mathias Woydt ◽  
Christoph Baumann ◽  
Joshua Jurs ◽  
...  

High temperature tribology is considered to begin from a minimum temperature of 300–350 °C, where organic base oils and polymers begin to decompose, until a temperature of 1000 °C. In this field of tribology, tests are typically run under dry or solid-state friction, unless a solid lubricant is used, since most lubricants will oxidize or break down when exposed to these extreme temperatures. Therefore, this form of tribotesting is useful to determine the friction, wear, and other tribological characteristics of coatings, ceramics, alloys, cermets, and similar materials. Additionally, high temperature tribology is important to further understand the frictional interactions and adhesive behavior of contacts that operate at these high temperatures. When considering measurements of the tribological parameters in a high temperature application, the standard Schwingung, Reibung, Verschleiž (SRV) (Oscillating, friction, wear, in English) reciprocating, linear-oscillatory tribometer can be modified for testing temperatures of up to 1000 °C by using a high temperature heating block. With this configuration, the instrument can accurately monitor many parameters of the tribosystem, such as coefficient of friction, electrical resistance, zero stroke point, sliding speed, and others. As a result, the SRV instrument is shown to be a powerful tool for high temperature tribotesting. This paper will provide an overview of this high temperature tribology test rig and will discuss its versatility and efficacy, and will show how it can effectively be implemented in both research and practical applications for the development of various coatings and other high temperature tribological contacts.


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