英语词汇“phi unit”的英英意思、用法、释义、翻译、读音、例句、短语、词组-英语词典

2. Geology. An index of particle size, equal to the negative of the logarithm to base 2 of the diameter in millimetres. Frequently attributive, as phi scale, phi unit, and written as ϕ.

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the world > the earth > earth sciences > geology > mineralogy > [noun] > particle size

phi1934

1934 W. C. Krumbein in Jrnl. Sedimentary Petrol. 4 76 ξ is the numerical value of the diameter... The substitution ϕ = −log₂ ξ, or ξ = (½)^ϕ, is made in part for typographical convenience, but also to introduce a convenient symbol that may be used for expressing grain diameters.

1949 Jrnl. Sedimentary Petrol. 19 76/1 The sieve interval of one phi unit is too large to make the true and nominal mean diameters reasonably equal for all size fractions.

1961 Jrnl. Sedimentary Petrol. 31 205/2 Comparison of the mean diameters of each pair of beach-dune samples..shows that there is little difference between the two. In these comparisons, 48 are within 0·2 phi of each other.

1971 E. F. McBride in R. E. Carver Procedures Sedimentary Petrol. vi. 110 The Phi scale is now used almost exclusively for computation and is gradually replacing the millimeter scale.

1978 Nature 14 Sept. 100/2 These sands exhibit good sorting, with standard deviations that are generally less than 0·8 phi units.

1988 M. E. Tucker Techniques in Sedimentol. (BNC) 73 The larger the particle phi number the finer the particle.

单词	phi unit
释义	> as lemmas phi unit 2. Geology. An index of particle size, equal to the negative of the logarithm to base 2 of the diameter in millimetres. Frequently attributive, as phi scale, phi unit, and written as ϕ. ΘΚΠ the world > the earth > earth sciences > geology > mineralogy > [noun] > particle size phi1934 1934 W. C. Krumbein in Jrnl. Sedimentary Petrol. 4 76 ξ is the numerical value of the diameter... The substitution ϕ = −log₂ ξ, or ξ = (½)^ϕ, is made in part for typographical convenience, but also to introduce a convenient symbol that may be used for expressing grain diameters. 1949 Jrnl. Sedimentary Petrol. 19 76/1 The sieve interval of one phi unit is too large to make the true and nominal mean diameters reasonably equal for all size fractions. 1961 Jrnl. Sedimentary Petrol. 31 205/2 Comparison of the mean diameters of each pair of beach-dune samples..shows that there is little difference between the two. In these comparisons, 48 are within 0·2 phi of each other. 1971 E. F. McBride in R. E. Carver Procedures Sedimentary Petrol. vi. 110 The Phi scale is now used almost exclusively for computation and is gradually replacing the millimeter scale. 1978 Nature 14 Sept. 100/2 These sands exhibit good sorting, with standard deviations that are generally less than 0·8 phi units. 1988 M. E. Tucker Techniques in Sedimentol. (BNC) 73 The larger the particle phi number the finer the particle. extracted from phin. < as lemmas
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