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Izbash Formula
The Izbash formula is a formula for the stability calculation of armourstone in running water. The stability of granular material in flow can be determined by the Shields formula or the Izbash formula. The first is more suitable for fine grain material (such as sand and gravel), while the Izbash formula is more suitable for larger stone. The Izbash formula was developed by Sergei Vladimirovich Izbash. In general form, the formula : \frac = 1,7 ... or ... \Delta d = 0,7 \frac where: :''uc'' = flow rate in the vicinity of the stone :Δ = relative density of the stone (= (''ρs'' -''ρw'')/''ρw'') where ''ρs'' is the density of the stone and ''ρw'' is the density of the water :''g'' = acceleration of gravity :''d'' = diameter of the stone The coefficient 1.7 is the experimental constant measured by Izbash. In fact, this constant contains two components, namely an effect for friction, inertia, etc. and a component that describes the turbulent character of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armourstone
Armourstone is a generic term for broken stone with stone masses between (very coarse Construction aggregate, aggregate) that is suitable for use in hydraulic engineering. Dimensions and characteristics for armourstone are laid down in European Standard EN13383. In the United States, there are a number of different standards and publications setting out different methodologies for classifying armourstone, ranging from weight-based classifications to gradation curves and size-based classifications. Stone Classes European Practice to EN13383 Armourstone is available in standardised stone classes, defined by both a lower and upper value of the stone mass within these classes. For instance, Class 60-300 signifies that up to 10% of the stones weigh less than and up to 30% weigh more than . The standard also mentions values which shouldn't be exceeded by 5% or 3%. For particular applications like a top layer for a breakwater (structure), breakwater or bank protection, the me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shields Formula
The Shields formula is a formula for the stability calculation of granular material (sand, gravel) in running water. The stability of granular material in flow can be determined by the Shields formula or the Izbash formula. The first is more suitable for fine grain material (such as sand and gravel), while the Izbash formula is more suitable for larger stone. The Shields formula was developed by Albert F. Shields (1908-1974). In fact, the Shields method determines whether or not the soil material will move. The Shields parameter thus determines whether or not there is a beginning of movement. Derivation Movement of (loose grained) soil material occurs when the shear pressure exerted by the water on the soil is greater than the resistance the soil provides. This dimensionless ratio (the Shields parameter) was first described by Albert Shields and reads: :\Psi_c*=\frac = \frac, in which is * \tau_c the critical bottom shear stress; * \rho_s is density of sediment; * \rho_ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sergei Vladimirovich Izbash
Sergius is a male given name of Ancient Roman origin after the name of the Latin ''gens'' Sergia or Sergii of regal and republican ages. It is a common Christian name, in honor of Saint Sergius, or in Russia, of Saint Sergius of Radonezh, and has been the name of four popes. It has given rise to numerous variants, present today mainly in the Romance (Serge, Sergio, Sergi) and Slavic languages (Serhii, Sergey, Serguei). It is not common in English, although the Anglo-French name Sergeant is possibly related to it. Etymology The name originates from the Roman ''nomen'' (patrician family name) ''Sergius'', after the name of the Roman ''gens'' of Latin origins Sergia or Sergii from Alba Longa, Old Latium, counted by Theodor Mommsen as one of the oldest Roman families, one of the original 100 ''gentes originarie''. It has been speculated to derive from a more ancient Etruscan name but the etymology of the nomen Sergius is problematic. Chase hesitantly suggests a connection ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematically, density is defined as mass divided by volume: : \rho = \frac where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure. To simplify comparisons of density across different s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slope Effect Of A Current
In mathematics, the slope or gradient of a Line (mathematics), line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is used for slope, but its earliest use in English appears in Matthew O'Brien (mathematician), O'Brien (1844) who wrote the equation of a straight line as and it can also be found in Isaac Todhunter, Todhunter (1888) who wrote it as "''y'' = ''mx'' + ''c''". Slope is calculated by finding the ratio of the "vertical change" to the "horizontal change" between (any) two distinct points on a line. Sometimes the ratio is expressed as a quotient ("rise over run"), giving the same number for every two distinct points on the same line. A line that is decreasing has a negative "rise". The line may be practical – as set by a Surveying, road surveyor, or in a diagram that models a road or a roof either as a description or as a plan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
