scholarly journals The emission constants of metals in the near infra-red

1933 ◽  
Vol 142 (847) ◽  
pp. 466-490 ◽  
Keyword(s):  
Cross Section ◽  
Specific Resistance ◽  
Wave Length ◽  
Electromagnetic Theory ◽  
Absolute Temperature ◽  
Restricted Range ◽  
Electron Theory ◽  
Long Wave ◽  
Infra Red ◽  
Made In

In the far infra-red, the reflecting power, R, of a metal at a wave-length, λ, is connected with its specific resistance, ρ, by the Hagen-Rubens relation, 1 - R = k √ρ/λ, where k is a constant with the value 0·365 when λ is measured in μ., and ρ is the resistance of a rod of the metal 1 metre in length and 1 sq. mm. in cross-section. The relation has only a restricted range of validity: for it is based theoretically on the electromagnetic theory, which does not embody the modern conceptions of the electron theory; and a restriction for a lower wave-length limit is made in the deduction of the formula itself. Hagen and Rubens have subjected the formula to a rigid test by a series of emission measurements. At wave-lengths of 25·5 and 8·85 μ, the calculated and observed emissivities agreed usually to within about 10%. Further experiments at the same wave-lengths showed, moreover, that the emissivity changed with temperature in the manner demanded by the relation. It follows that the emissivity of a metal at sufficiently long wave-lengths is roughly proportional to the square-root of its absolute temperature.

Searching for the causes why some of the paintings by Mihaly Munkacsy are darkening

1990 ◽  
Vol 48 (2) ◽  
pp. 204-205
Author(s):  
Imre Pozsgai ◽  
Klara Erdöhalmi-Torok
Keyword(s):  
Electron Beam ◽  
Cross Section ◽  
Polyester Resin ◽  
National Gallery ◽  
X Ray ◽  
Art Historians ◽  
Made In ◽  
Grinding And Polishing

The paintings by the great Hungarian master Mihaly Munkacsy (1844-1900) made in an 8-9 years period of his activity are deteriorating. The most conspicuous sign of the deterioration is an intensive darkening. We have made an attempt by electron beam microanalysis to clarify the causes of the darkening. The importance of a study like this is increased by the fact that a similar darkening can be observed on the paintings by Munkacsy’s contemporaries e.g Courbet and Makart. A thick brown mass the so called bitumen used by Munkacsy for grounding and also as a paint is believed by the art historians to cause the darkening.For this study, paint specimens were taken from the following paintings: “Studio”, “Farewell” and the “Portrait of the Master’s Wife”, all of them are the property of the Hungarian National Gallery. The paint samples were embedded in a polyester resin “Poly-Pol PS-230” and after grinding and polishing their cross section was used for x-ray mapping.

Wave Forces on a Stationary Platform of Elliptical Shape

1973 ◽  
Vol 17 (02) ◽  
pp. 61-71
Author(s):  
H. S. Chen ◽  
C. C. Mei
Keyword(s):  
Diffraction Problem ◽  
Wave Length ◽  
Practical Interest ◽  
Vertical Cylinder ◽  
Present Theory ◽  
Wave Forces ◽  
Mathieu Functions ◽  
Body Type ◽  
Elliptical Cross ◽  
Long Wave

Exciting forces and moments due to plane incident waves on a stationary platform are studied in this paper. The platform is a vertical cylinder with a finite draft and elliptical cross section. The mathematical solution to the diffraction problem is obtained on the basis of the linearized long wave approximation. Numerical results via Mathieu functions are presented for a shiplike body with beam-to-length ratio Various draft-to-depth ratios and angles of incidence are considered. Results have been checked with the limiting case of a circular cylinder for the long-wave length range. Aside from its own practical interest, the present theory provides a basis for comparison with other approximate theories of slender-body type and serves as a prelude to the corresponding calculations for arbitrary wavelengths.

scholarly journals On the surface-tension of liquids investigated by the method of jet vibration

1907 ◽  
Vol 80 (535) ◽  
pp. 26-27 ◽  
Keyword(s):  
Surface Tension ◽  
Cross Section ◽  
Wave Length ◽  
Standing Waves ◽  
Exact Determination ◽  
Relative Measurements

1. According to Lord Rayleigh’s theory of jet-vibrations, measurement of the length of the standing waves and the velocity and cross-section of a jet, together with the density of the liquid, affords the necessary constants for the calculation of the surface-tension. Notwithstanding the great fundamental advantages of this method, it has only been used in very few cases, and only for relative measurements of the surface-tension. The explanation hereof is to be found in the great difficulties connected with the adequate exact determination of the wave-length, and cross-section or velocity of the jet. As none of the methods in use for the measurement of these quantities could be taken as satisfactory, the main object of this investigation has been to work out really good methods for them.

The continuous absorption of light in alkali-metal vapours

1953 ◽  
Vol 219 (1136) ◽  
pp. 89-101 ◽  
Keyword(s):  
Cross Section ◽  
Alkali Metals ◽  
Theoretical Calculations ◽  
Wave Length ◽  
Energy Difference ◽  
Continuous Absorption ◽  
Absorption Of Light ◽  
Sodium Vapour ◽  
Good Agreement ◽  
Dipole Length

The first section of this paper is an account of some experiments on the absorption of light in sodium vapour from the series limit at 2412 Å to about 1600 Å (an energy difference of 2·6 eV). The absorption cross-section at the limit is 11·6 ± 1·2 x 10 -20 cm 2 . The cross-section decreases giving a minimum of 1·3 ± 0·6 x 10 -20 cm 2 at 1900 Å and then increases to 1600 Å. A theoretical calculation by Seaton based on the dipole-length formula gives good agreement with the experiments at the series limit and also correctly predicts the wave-length for the minimum, but it predicts a significantly lower absorption at the minimum. The experiments described in the first section of the paper conclude a series on the absorption of light in the alkali metals. The second section consists of a general discussion of the results of these experiments and of their relation to theoretical calculations. There is good agreement between theory and experiment except in regard to the magnitude of the absorption at the minimum.

scholarly journals Radiation torque on a spherical birefringent particle in the long wave length limit: analytical calculation

2005 ◽  
Vol 13 (14) ◽  
pp. 5192 ◽  
Author(s):  
Nian Ji ◽  
Mengkun Liu ◽  
Jihao Zhou ◽  
Zhifang Lin ◽  
S. T. Chui
Keyword(s):  
Wave Length ◽  
Analytical Calculation ◽  
Long Wave

scholarly journals Green’s Relations on a Semigroup of Transformations with Restricted Range that Preserves an Equivalence Relation and a Cross-Section

Mathematics ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 134
Author(s):  
Chollawat Pookpienlert ◽  
Preeyanuch Honyam ◽  
Jintana Sanwong
Keyword(s):  
Cross Section ◽  
Equivalence Relation ◽  
Nonempty Subset ◽  
Identity Relation ◽  
Green’S Relations ◽  
Restricted Range ◽  
Green's Relations ◽  
Semigroup Of Transformations

Let T(X,Y) be the semigroup consisting of all total transformations from X into a fixed nonempty subset Y of X. For an equivalence relation ρ on X, let ρ^ be the restriction of ρ on Y, R a cross-section of Y/ρ^ and define T(X,Y,ρ,R) to be the set of all total transformations α from X into Y such that α preserves both ρ (if (a,b)∈ρ, then (aα,bα)∈ρ) and R (if r∈R, then rα∈R). T(X,Y,ρ,R) is then a subsemigroup of T(X,Y). In this paper, we give descriptions of Green’s relations on T(X,Y,ρ,R), and these results extend the results on T(X,Y) and T(X,ρ,R) when taking ρ to be the identity relation and Y=X, respectively.

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