WordNet

being or involving basic facts or principles; "the fundamental laws of the universe"; "a fundamental incomatibility between them"; "these rudimentary truths"; "underlying principles" (同)rudimentary, underlying
the lowest tone of a harmonic series (同)fundamental_frequency, first harmonic
any factor that could be considered important to the understanding of a particular business; "fundamentals include a companys growth, revenues, earnings, management, and capital structure"
far-reaching and thoroughgoing in effect especially on the nature of something; "the fundamental revolution in human values that has occurred"; "the book underwent fundamental changes"; "committed the fundamental error of confusing spending with extravagance"; "profound social changes" (同)profound
the number of observations in a given statistical category (同)absolute frequency
the number of occurrences within a given time period; "the frequency of modulation was 40 cycles per second"; "the frequency of his seizures increased as he grew older" (同)frequence, oftenness
the ratio of the number of observations in a statistical category to the total number of observations (同)relative frequency
principles from which other truths can be derived; "first you must learn the fundamentals"; "lets get down to basics" (同)basics, fundamental principle, basic_principle, bedrock

PrepTutorEJDIC

『基本的な』,基礎の / 《補語にのみ用いて》(…に)絶対に必要な《『to』+『名』》 / 《名詞の前にのみ用いて》本質的な / (…の)基本,根本,原理《+『of』+『名』》
〈U〉しばしば起こること,頻繁 / 〈C〉頻度数,(発生・生現などの)回数 / 〈C〉振動数;周波数

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/26 16:49:39」(JST)

wiki en

Vibration and standing waves in a string, The fundamental and the first 6 overtones

The fundamental frequency, often referred to simply as the fundamental, is defined as the lowest frequency of a periodic waveform. In terms of a superposition of sinusoids (e.g. Fourier series), the fundamental frequency is the lowest frequency sinusoidal in the sum. In some contexts, the fundamental is usually abbreviated as f₀ (or FF), indicating the lowest frequency counting from zero.^[1]^[2]^[3] In other contexts, it is more common to abbreviate it as f₁, the first harmonic.^[4]^[5]^[6]^[7]^[8] (The second harmonic is then f₂ = 2⋅f₁, etc. In this context, the zeroth harmonic would be 0 Hz.)

Explanation

All sinusoidal and many non-sinusoidal waveforms are periodic, which is to say they repeat exactly over time. A single period is thus the smallest repeating unit of a signal, and one period describes the signal completely. We can show a waveform is periodic by finding some period T for which the following equation is true:

Where x(t) is the function of the waveform.

This means that for multiples of some period T the value of the signal is always the same. The least possible value of T for which this is true is called the fundamental period and the fundamental frequency (f₀) is:

Where f₀ is the fundamental frequency and T is the fundamental period.

F0leftclosed

F0rightclosed

For a tube of length L with one end closed and the other end open the wavelength of the fundamental harmonic is 4L, as indicated by the top two animations on the right. Hence,

Therefore, using the relation

,

where v is the speed of the wave, we can find the fundamental frequency in terms of the speed of the wave and the length of the tube:

F0bothclosed

F0bothopen

If the ends of the same tube are now both closed or both opened as in the bottom two animations on the right, the wavelength of the fundamental harmonic becomes 2L. By the same method as above, the fundamental frequency is found to be

At 20 °C (68 °F) the speed of sound in air is 343 m/s (1129 ft/s). This speed is temperature dependent and does increase at a rate of 0.6 m/s for each degree Celsius increase in temperature (1.1 ft/s for every increase of 1 °F).

The velocity of a sound wave at different temperatures:-

v = 343.2 m/s at 20 °C
v = 331.3 m/s at 0 °C

Mechanical systems

Consider a spring, fixed at one end and having a mass attached to the other; this would be a single degree of freedom (SDoF) oscillator. Once set into motion it will oscillate at its natural frequency. For a single degree of freedom oscillator, a system in which the motion can be described by a single coordinate, the natural frequency depends on two system properties: mass and stiffness; (providing the system is undamped). The radian frequency, ω_n, can be found using the following equation:

Where:
k = stiffness of the spring
m = mass
ω_n = radian frequency (radians per second)

From the radian frequency, the natural frequency, f_n, can be found by simply dividing ω_n by 2π. Without first finding the radian frequency, the natural frequency can be found directly using:

Where:
f_n = natural frequency in hertz (cycles/second)
k = stiffness of the spring (Newtons/meter or N/m)
m = mass(kg)
while doing the modal analysis of structures and mechanical equipment, the frequency of 1st mode is called fundamental frequency.

References

^ "sidfn". Phon.ucl.ac.uk. Retrieved 2012-11-27.
^ "Phonetics and Theory of Speech Production". Acoustics.hut.fi. Retrieved 2012-11-27.
^ "Fundamental Frequency of Continuous Signals" (PDF). Fourier.eng.hmc.edu. Retrieved 2012-11-27.
^ "Standing Wave in a Tube II - Finding the Fundamental Frequency" (PDF). Nchsdduncanapphysics.wikispaces.com. Retrieved 2012-11-27.
^ "Physics: Standing Waves" (PDF). Physics.kennesaw.edu. Retrieved 2012-11-27.
^ "Phys 1240: Sound and Music" (PDF). Colorado.edu. Retrieved 2012-11-27.
^ "Standing Waves on a String". Hyperphysics.phy-astr.gsu.edu. Retrieved 2012-11-27.
^ "Creating musical sounds - OpenLearn - Open University". Open University. Retrieved 2014-06-04.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. T波（再分極）の交互脈：技術的側面 t wave repolarization alternans technical aspects
2. 成人における高頻度人工呼吸 high frequency ventilation in adults
3. 新生児における機械的人工換気 mechanical ventilation in neonates
4. 心エコー検査の要点：物理学および計測 echocardiography essentials physics and instrumentation
5. 気管支肺異形成症の予防 prevention of bronchopulmonary dysplasia

English Journal

Sound field measurement in a double layer cavitation cluster by rugged miniature needle hydrophones.

Koch C1.
Ultrasonics sonochemistry.Ultrason Sonochem.2016 Mar;29:439-46. doi: 10.1016/j.ultsonch.2014.05.018. Epub 2014 Jun 2.
During multi-bubble cavitation the bubbles tend to organize themselves into clusters and thus the understanding of properties and dynamics of clustering is essential for controlling technical applications of cavitation. Sound field measurements are a potential technique to provide valuable experimen
PMID 24953962

Characterization of un-plasticized and propylene carbonate plasticized carboxymethyl cellulose doped ammonium chloride solid biopolymer electrolytes.

Ahmad NH1, Isa MI2.
Carbohydrate polymers.Carbohydr Polym.2016 Feb 10;137:426-32. doi: 10.1016/j.carbpol.2015.10.092. Epub 2015 Nov 2.
Two solid biopolymer electrolytes (SBEs) systems of carboxymethyl cellulose doped ammonium chloride (CMC-AC) and propylene carbonate plasticized (CMC-AC-PC) were prepared via solution casting technique. The ionic conductivity of SBEs were analyzed using electrical impedance spectroscopy (EIS) in the
PMID 26686147

NCRP Program Area Committee 6: Radiation Measurements and Dosimetry.

Simon SL1, Zeman GH.
Health physics.Health Phys.2016 Feb;110(2):113-5. doi: 10.1097/HP.0000000000000405.
Program Area Committee (PAC) 6 of the National Council on Radiation Protection and Measurements provides guidance for radiation measurements and dosimetry-one of the most fundamental scientific areas of the Council's expertise. Seminal reports published by PAC 6 over many decades have documented the
PMID 26717161

Japanese Journal

騒音・低周波音問題防止の基礎と対応 (環境特集)

井上保雄
紙パ技協誌 = Japan TAPPI journal 66(12), 1317-1332, 2012-12
NAID 40019497566

タグシステムに用いる拡散符号を共有しない擬似CDMA通信の提案

光藤雄一
情報処理学会研究報告. UBI, [ユビキタスコンピューティングシステム] 2012-UBI-36(11), 1-4, 2012-10-25
CDMA 通信方式では,拡散符号と呼ばれる数列によって,多数の送受信局が接続する.送受信器のペアは拡散符号の共有によって定められるので,同じ周波数帯を使用することができる.実世界で光タグシステムを実装する際に,同じ周波数帯を利用できる特徴は有用であるが,拡散符号を共有することが難しい.そこで本稿では,拡散符号によって信号を拡散するが,受信時に拡散符号を必要としない手法を提案し,その通信品質を評価す …
NAID 110009478244