Q, letter of the alphabet
Q, 17th letter of the alphabet alphabet [Gr. alpha-beta, like Eng. ABC], system of writing , theoretically having a one-for-one relation between character (or letter) and phoneme (see phonetics ). Few alphabets have achieved the ideal exactness...... Click the link for more information. , corresponding to the koppa of western Greek alphabets. U must follow the letter in English (e.g., queen, question), and the combination properly represents a sound much like the true voiceless labiovelar stop (also represented by the combination kw).
Q, English author
Q: see Quiller-Couch, Sir Arthur Thomas Q, 1863–1944, English author. Among the novels of his native Cornwall are Dead Man's Rock (1887) and Hetty Wesley (1903), which are romantic in spirit yet distinguished for their clear and colorful style...... Click the link for more information. .
Q
(nuclear physics)
(physics)
A measure of the ability of a system with periodic behavior to store energy equal to 2π times the average energy stored in the system divided by the energy dissipated per cycle. Also known asQfactor; quality factor; storage factor.
(thermodynamics)
A unit of heat energy, equal to 1018British thermal units, or approximately 1.055 × 1021joules.
Q (electricity)
Often called the quality factor of a circuit, Q is defined in various ways, depending upon the particular application. In the simple RL and RC series circuits, Q is the ratio of reactance to resistance, as in Eqs. (1),
(1) 
where XL is the inductive reactance, XC is the capacitive reactance, and R is the resistance. An important application lies in the dissipation factor or loss angle when the constants of a coil or capacitor are measured by means of the alternating-current bridge. Q has greater practical significance with respect to the resonant circuit, and a basic definition is given by Eq. (2),
(2) 
where Q0 means evaluation at resonance. For certain circuits, such as cavity resonators, this is the only meaning Q can have. For the RLC series resonant circuit with resonant frequency f0, Eq. (3)
(3) 
holds, where R is the total circuit resistance, L is the inductance, and C is the capacitance. Q0 is the Q of the coil if it contains practically the total resistance R. The greater the value of Q0, the sharper will be the resonance peak. The practical case of a coil of high Q0 in parallel with a capacitor also leads to Q0 = 2&pgr;f0L/R. R is the total series resistance of the loop, although the capacitor branch usually has negligible resistance.
In terms of the resonance curve, Eq. (4) holds,
(4) 
where f0 is the frequency at resonance, and f1 and f2 are the frequencies at the half-power points.| (language) | Q - A very high level language by Per Bothner based
on lazy generalised sequences. Q has lexical scope, and
some support for logic programmingnd constraint
programming. The language includes small subsets of Common Lisp and Scheme. Q was a test-bed for programming language ideas. Where APL uses arrays for looping, Q uses generalised sequences which may be infinite and may be stored or calculated on demand. It has macros, primitives to run programs, and an interactive command language. Q is implemented in C++, and comes with an interpreter, compiler framework, libraries, and documentation. It runs on Linux and SUN-4 and should work on any 32-bit Unix. Latest version: 1, as of 1993-06-07. Development stopped in 1994. http://kelso.bothner.com/~per/software/#Q . E-mail: Per Bothner <per@bothner.com>. |
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