“resonance”的概念、定义、翻译、参考文献-科学参考

resonance

Physics

1. An oscillation of a system at its natural frequency of vibration, as determined by the physical parameters of the system. It has the characteristic that large amplitude vibrations will ultimately result from low-power driving of the system. Resonance can occur in atoms and molecules, mechanical systems, and electrical circuits (see resonant circuit; resonant cavity).

2. A very short-lived elementary particle that can be regarded as an excited state of a more stable particle. Resonances decay by the strong interaction (see fundamental interactions) in 10⁻²⁴ second.

Mathematics

Suppose that a body capable of performing oscillations is subject to an applied force which is itself oscillatory and not subject to any resistive force. In certain circumstances the body may oscillate with an amplitude that, in theory, increases indefinitely. This happens when the applied force has the same frequency as a natural frequency of the body, and then resonance is said to occur. For example, if the equation $m \ddot{x} + k x = F cos Ω t$ holds, there is resonance when $Ω = \sqrt{k / m,}$ in which case the solution of the equation involves the particular integral

$\frac{F t}{2 \sqrt{k m}} sin \sqrt{\frac{k}{m}} t,$

which gives oscillations of increasing amplitude.
http://www.acoustics.salford.ac.uk/feschools/waves/shm3.htm Animations and videos of forced oscillation and resonance.

Chemistry

The representation of the structure of a molecule by two or more conventional formulae. For example, the formula of methanal can be represented by a covalent structure H₂C=O, in which there is a double bond in the carbonyl group. It is known that in such compounds the oxygen has some negative charge and the carbon some positive charge. The true bonding in the molecule is somewhere between H₂C=O and the ionic compound H₂C⁺O⁻. It is said to be a resonance hybrid of the two, indicated by
$H_{2} C = O \leftrightarrow H_{2} C^{+} O^{-}$
The two possible structures are called canonical forms, and they need not contribute equally to the actual form. Note that the double-headed arrow does not imply that the two forms are in equilibrium. In valence-bond theory the overall wave function for a molecule is a linear superposition of the wave functions of the canonical forms, with appropriately weighted coefficients to reflect the contribution of a particular canonical form to the overall structure.

Electronics and Electrical Engineering

A condition existing when an oscillatory circuit responds with maximum amplitude to a periodic driving force so that a relatively small amplitude of the driving force produces a large amplitude of oscillation. Resonance is achieved when the frequency of the driving force coincides with the natural undamped frequency of the oscillatory system. See also forced oscillations; resonant frequency; tuned circuit.

Geology and Earth Sciences

1. Condition of very large wave amplitude, occurring when the frequency of an external wave-generating force matches and amplifies a natural frequency for waves moving to and fro in an enclosed space such as an estuary.
2. The relationship in which the orbital period of one body is related to that of a second by a simple integer fraction (e.g. ½, ⅗). Such orbits are common in the solar system. Well-known examples include the Kirkwood Gaps in the Asteroid Belt and the Cassini Division in Saturn’s ring system (a particle moving in the Cassini Division has a period ½ that of Mimas, and ⅓ that of Enceladus).

单词	resonance
释义	resonance Physics 1. An oscillation of a system at its natural frequency of vibration, as determined by the physical parameters of the system. It has the characteristic that large amplitude vibrations will ultimately result from low-power driving of the system. Resonance can occur in atoms and molecules, mechanical systems, and electrical circuits (see resonant circuit; resonant cavity). 2. A very short-lived elementary particle that can be regarded as an excited state of a more stable particle. Resonances decay by the strong interaction (see fundamental interactions) in 10⁻²⁴ second. Mathematics Suppose that a body capable of performing oscillations is subject to an applied force which is itself oscillatory and not subject to any resistive force. In certain circumstances the body may oscillate with an amplitude that, in theory, increases indefinitely. This happens when the applied force has the same frequency as a natural frequency of the body, and then resonance is said to occur. For example, if the equation $m \ddot{x} + k x = F cos Ω t$ holds, there is resonance when $Ω = \sqrt{k / m,}$ in which case the solution of the equation involves the particular integral $\frac{F t}{2 \sqrt{k m}} sin \sqrt{\frac{k}{m}} t,$ which gives oscillations of increasing amplitude. http://www.acoustics.salford.ac.uk/feschools/waves/shm3.htm Animations and videos of forced oscillation and resonance. Chemistry The representation of the structure of a molecule by two or more conventional formulae. For example, the formula of methanal can be represented by a covalent structure H₂C=O, in which there is a double bond in the carbonyl group. It is known that in such compounds the oxygen has some negative charge and the carbon some positive charge. The true bonding in the molecule is somewhere between H₂C=O and the ionic compound H₂C⁺O⁻. It is said to be a resonance hybrid of the two, indicated by $H_{2} C = O \leftrightarrow H_{2} C^{+} O^{-}$ The two possible structures are called canonical forms, and they need not contribute equally to the actual form. Note that the double-headed arrow does not imply that the two forms are in equilibrium. In valence-bond theory the overall wave function for a molecule is a linear superposition of the wave functions of the canonical forms, with appropriately weighted coefficients to reflect the contribution of a particular canonical form to the overall structure. Electronics and Electrical Engineering A condition existing when an oscillatory circuit responds with maximum amplitude to a periodic driving force so that a relatively small amplitude of the driving force produces a large amplitude of oscillation. Resonance is achieved when the frequency of the driving force coincides with the natural undamped frequency of the oscillatory system. See also forced oscillations; resonant frequency; tuned circuit. Geology and Earth Sciences 1. Condition of very large wave amplitude, occurring when the frequency of an external wave-generating force matches and amplifies a natural frequency for waves moving to and fro in an enclosed space such as an estuary. 2. The relationship in which the orbital period of one body is related to that of a second by a simple integer fraction (e.g. ½, ⅗). Such orbits are common in the solar system. Well-known examples include the Kirkwood Gaps in the Asteroid Belt and the Cassini Division in Saturn’s ring system (a particle moving in the Cassini Division has a period ½ that of Mimas, and ⅓ that of Enceladus).
随便看	phase corrector phased array phase defect phase delay phase-detect autofocus system phase detector phase deviation phase diagram phase difference phase discriminator phase distortion phased linear array phased retirement phase-encoded phase II metabolism phase I metabolism phase inverter phase lag phase layering phase-locked loop phase-lock loop phase modulation phase of a complex number phase plane phase problem