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Self-oscillation
Self-oscillation is the generation and maintenance of a periodic motion by a source of power that lacks any corresponding periodicity. The oscillator itself controls the phase with which the external power acts on it. Self-oscillators are therefore distinct from forced and parametric resonators, in which the power that sustains the motion must be modulated externally. In linear systems, self-oscillation appears as an instability associated with a negative damping term, which causes small perturbations to grow exponentially in amplitude. This negative damping is due to a positive feedback between the oscillation and the modulation of the external source of power. The amplitude and waveform of steady self-oscillations are determined by the nonlinear characteristics of the system. Self-oscillations are important in physics, engineering, biology, and economics. History of the subject The study of self-oscillators dates back to the early 1830s, with the work of Robert Wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philippe Le Corbeiller
Philippe Emmanuel Le Corbeiller (January 11, 1891 – July 24, 1980) was a French-American electrical engineer, mathematician, physicist, and educator. After a career in France as an expert on the electronics of telecommunications, he became a professor of applied physics and general education at Harvard University. His most important scientific contributions were in the theory and applications of nonlinear systems, including self-oscillators. Career in France Son of author and politician Jean-Maurice Le Corbeiller and his wife Marguerite Dreux, Philippe entered the École Polytechnique in 1910, training there in engineering and the mathematical sciences. During World War I he served in the French Signal Corps, earning the ''croix de guerre'' and joining the staff of Marshal Ferdinand Foch. After the war, Le Corbeiller worked on telegraphy and radio systems. In 1926 he completed a doctorate in mathematics from the Sorbonne. His dissertation was on the arithmetic the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlinear System
In mathematics and science, a nonlinear system (or a non-linear system) is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other scientists since most systems are inherently nonlinear in nature. Nonlinear dynamical systems, describing changes in variables over time, may appear chaotic, unpredictable, or counterintuitive, contrasting with much simpler linear systems. Typically, the behavior of a nonlinear system is described in mathematics by a nonlinear system of equations, which is a set of simultaneous equations in which the unknowns (or the unknown functions in the case of differential equations) appear as variables of a polynomial of degree higher than one or in the argument of a function which is not a polynomial of degree one. In other words, in a nonlinear system of equations, the equation(s) to be solved cannot be written as a lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hunting Oscillation
Hunting oscillation is a self-oscillation, usually unwanted, about an Mechanical equilibrium, equilibrium. The expression came into use in the 19th century and describes how a system "hunts" for equilibrium. The expression is used to describe phenomena in such diverse fields as electronics, aviation, biology, and railway engineering. Railway wheelsets A classical hunting oscillation is a swaying motion of a railway vehicle (often called ''truck hunting'' or ''bogie hunting'') caused by the Adhesion railway#Directional stability and hunting instability, coning action on which the directional Directional stability, stability of an adhesion railway depends. It arises from the interaction of adhesion forces and inertial forces. At low speed, adhesion dominates but, as the speed increases, the adhesion forces and inertial forces become comparable in magnitude and the oscillation begins at a critical speed. Above this speed, the motion can be violent, damaging track and wheels and pote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfred-Marie Liénard
Alfred-Marie Liénard (2 April 1869 in Amiens Amiens (English: or ; ; , or ) is a city and Communes of France, commune in northern France, located north of Paris and south-west of Lille. It is the capital of the Somme (department), Somme Departments of France, department in the region ... – 29 April 1958 in Paris), was a French physicist and engineer. He is best known for his derivation of the Liénard–Wiechert potentials. From 1887 to 1889 Liénard was a student at the École Polytechnique and from 1889 to 1892 at the École nationale supérieure des mines de Paris, École des mines de Paris. From 1892 to 1895 he was a mining engineer in Valencia, Spain, Valencia, Marseille, and Angers. From 1895 to 1908 he was professor at the École Nationale Supérieure des Mines de Saint-Étienne, École des Mines de Saint-Étienne and from 1908 to 1911 he was professor of electrical engineering at the École des Mines de Paris. In World War I he served in the French Army. Lié ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
André Blondel
André-Eugène Blondel (28 August 1863 – 15 November 1938) was a French engineer and physicist. He is the inventor of the electromechanical oscillograph and a system of photometric units of measurement. Life Blondel was born in Chaumont, Haute-Marne, France. His father was a magistrate from an old family in the town of Dijon. He was the best student from the town in his year. He went on to attend the École nationale des ponts et chaussées (School of Bridges and Roadways) and graduated first in his class in 1888. He was employed as an engineer by the Lighthouses and Beacons Service until he retired in 1927 as its general first class inspector.See IEEE Industry Applications Magazine May–June 2004 He became a professor of electrotechnology at the School of Bridges and Highways and the School of Mines in Paris.See Hebrew University of Jerusalem Very early in his career he suffered immobility due to a paralysis of his legs, which confined him to his room for 27 years, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self Excited Oscillation
In philosophy, the self is an individual's own being, knowledge, and values, and the relationship between these attributes. The first-person perspective distinguishes selfhood from personal identity. Whereas "identity" is (literally) sameness and may involve categorization and labeling, selfhood implies a first-person perspective and suggests potential uniqueness. Conversely, "person" is used as a third-person reference. Personal identity can be impaired in late-stage Alzheimer's disease and in other neurodegenerative diseases. Finally, the self is distinguishable from "others". Including the distinction between sameness and otherness, the self versus other is a research topic in contemporary philosophy and contemporary phenomenology (see also psychological phenomenology), psychology, psychiatry, neurology, and neuroscience. Although subjective experience is central to selfhood, the privacy of this experience is only one of many problems in the philosophy of self and scie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henri Poincaré
Jules Henri Poincaré (, ; ; 29 April 185417 July 1912) was a French mathematician, Theoretical physics, theoretical physicist, engineer, and philosophy of science, philosopher of science. He is often described as a polymath, and in mathematics as "The Last Universalist", since he excelled in all fields of the discipline as it existed during his lifetime. He has further been called "the Carl Friedrich Gauss, Gauss of History of mathematics, modern mathematics". Due to his success in science, along with his influence and philosophy, he has been called "the philosopher par excellence of modern science". As a mathematician and physicist, he made many original fundamental contributions to Pure mathematics, pure and applied mathematics, mathematical physics, and celestial mechanics. In his research on the three-body problem, Poincaré became the first person to discover a chaotic deterministic system which laid the foundations of modern chaos theory. Poincaré is regarded as the cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Closed-loop Transfer Function
In control theory, a closed-loop transfer function is a mathematical function describing the net result of the effects of a feedback control loop on the input signal to the plant under control. Overview The closed-loop transfer function is measured at the output. The output signal can be calculated from the closed-loop transfer function and the input signal. Signals may be waveforms, images, or other types of data streams. An example of a closed-loop block diagram, from which a transfer function may be computed, is shown below: The summing node and the ''G''(''s'') and ''H''(''s'') blocks can all be combined into one block, which would have the following transfer function: : \dfrac = \dfrac G(s) is called the feed forward transfer function, H(s) is called the feedback transfer function, and their product G(s)H(s) is called the open-loop transfer function. Derivation We define an intermediate signal Z (also known as error signal) shown as follows: Using this figur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nyquist Stability Criterion
In control theory and stability theory, the Nyquist stability criterion or Strecker–Nyquist stability criterion, independently discovered by the German electrical engineer at Siemens in 1930 and the Swedish-American electrical engineer Harry Nyquist at Bell Telephone Laboratories in 1932, is a graphical technique for determining the stability criterion, stability of a linear dynamical system. Because it only looks at the Nyquist plot of the Open-loop controller, open loop systems, it can be applied without explicitly computing the poles and zeros of either the closed-loop or open-loop system (although the number of each type of right-half-plane Singularity (mathematics), singularities must be known). As a result, it can be applied to systems defined by non-rational functions, such as systems with delays. In contrast to Bode plots, it can handle transfer functions with right half-plane singularities. In addition, there is a natural generalization to more complex systems with M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Routh–Hurwitz Stability Criterion
In the control theory, control system theory, the Routh–Hurwitz stability criterion is a mathematical test that is a necessary and sufficient condition for the stable polynomial, stability of a linear time-invariant system, linear time-invariant (LTI) dynamical system or control system. A stability theory, stable system is one whose output signal is bounded; the position, velocity or energy do not increase to infinity as time goes on. The Routh test is an efficient recursive algorithm that English mathematician Edward John Routh proposed in 1876 to determine whether all the root of a function, roots of the characteristic polynomial of a linear system have negative real parts. German mathematician Adolf Hurwitz independently proposed in 1895 to arrange the coefficients of the polynomial into a square matrix, called the Routh–Hurwitz matrix, Hurwitz matrix, and showed that the polynomial is stable if and only if the sequence of determinants of its principal submatrices are all po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Equilibrium
In classical mechanics, a particle is in mechanical equilibrium if the net force on that particle is zero. By extension, a physical system made up of many parts is in mechanical equilibrium if the net force on each of its individual parts is zero. In addition to defining mechanical equilibrium in terms of force, there are many alternative definitions for mechanical equilibrium which are all mathematically equivalent. * In terms of momentum, a system is in equilibrium if the momentum of its parts is all constant. * In terms of velocity, the system is in equilibrium if velocity is constant. * In a rotational mechanical equilibrium the angular momentum of the object is conserved and the net torque is zero. More generally in conservative systems, equilibrium is established at a point in Configuration space (physics), configuration space where the gradient of the potential energy with respect to the generalized coordinates is zero. If a particle in equilibrium has zero velocity, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitic Oscillation
Parasitic oscillation is an undesirable electronic oscillation (cyclic variation in output voltage or current) in an electronic or digital device. It is often caused by feedback in an amplifying device. The problem occurs notably in RF, audio, and other electronic amplifiers as well as in digital signal processing. It is one of the fundamental issues addressed by control theory. Parasitic oscillation is undesirable for several reasons. The oscillations may be coupled into other circuits or radiate as radio waves, causing electromagnetic interference (EMI) to other devices. In audio systems, parasitic oscillations can sometimes be heard as annoying sounds in the speakers or earphones. The oscillations waste power and may cause undesirable heating. For example, an audio power amplifier that goes into parasitic oscillation may generate enough power to damage connected speakers. A circuit that is oscillating will not amplify linearly, so desired signals passing through the stage w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
