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2024年5月10日 · The resistivity can be expressed using the SI unit ohm metre (Ω⋅m) — i.e. ohms multiplied by square metres (for the cross-sectional area) then divided by metres (for the length).Both resistance and resistivity describe how difficult it is to make electrical current flow through a material, but unlike resistance, resistivity is an intrinsic property and does not depend on geometric ...
- ρ
- ohm metre (Ω⋅m)
- kg⋅m³⋅s−3⋅A−2
3 天前 · Principal component analysis ( PCA) is a linear dimensionality reduction technique with applications in exploratory data analysis, visualization and data preprocessing . The data is linearly transformed onto a new coordinate system such that the directions (principal components) capturing the largest variation in the data can be easily identified.
2 天前 · In mathematics, the logarithm is the inverse function to exponentiation. That means that the logarithm of a number x to the base b is the exponent to which b must be raised to produce x. For example, since 1000 = 103, the logarithm base 10 {\displaystyle 10} of 1000 is 3, or log10 (1000) = 3. The logarithm of x to base b is denoted as logb (x ...
2 天前 · A key mathematical property of the Pearson correlation coefficient is that it is invariant under separate changes in location and scale in the two variables. That is, we may transform X to a + bX and transform Y to c + dY, where a, b, c, and d are constants with b, d > 0, without changing the correlation coefficient.
2 天前 · The 828-metre (2,717 ft) tall Burj Khalifa in Dubai has been the tallest building since 2010. The Burj Khalifa has been classified as megatall. A diagram showing the tallest buildings as of 2024 This is a list of the tallest buildings.Tall buildings, such as skyscrapers, are intended here as enclosed structures with continuously occupiable floors and a height of at least 340 metres (1,120 ft).
1 天前 · Richard Phillips Feynman (/ ˈ f aɪ n m ə n /; May 11, 1918 – February 15, 1988) was an American theoretical physicist, known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of the superfluidity of supercooled liquid helium, as well as his work in particle physics for which he proposed the parton model.
1 天前 · Visual comparison of convolution, cross-correlation, and autocorrelation.For the operations involving function , and assuming the height of is 1.0, the value of the result at 5 different points is indicated by the shaded area below each point. The symmetry of is the reason and are identical in this example. ...
