scholarly journals Further experiments on the variation of wave-length of the oscillations generated by an ionic valve due to changes in filament current

1920 ◽  
Vol 97 (683) ◽  
pp. 191-196
Keyword(s):  
Wave Length ◽  
Oscillatory Circuit ◽  
Filament Current ◽  
Maximum Value ◽  
Made In ◽  
Main Oscillator

In the course of a research on the effects produced on the wave-length of the oscillations given out by a triode maintained oscillator when various changes were made in the circuit, Eccles and Vincent showed that in an oscillatory circuit maintained by a B valve with a grid coil coupling (like the two oscillatory circuits in fig. 1) the wave-length varies slightly with the filament current and has a maximum value for a certain filament current. In all cases investigated it was found possible so to adjust the coupling between the grid coil and main oscillator coil as to allow the filament current to be set to make the wave-length a maximum.

scholarly journals Analytic materials

2016 ◽  
Vol 472 (2195) ◽  
pp. 20160613 ◽  
Author(s):  
Graeme W. Milton
Keyword(s):  
Connected Domain ◽  
Free Field ◽  
Exact Results ◽  
Two Dimensional ◽  
Simply Connected Domain ◽  
Maximum Value ◽  
Two Dimensional Materials ◽  
The Subject ◽  
Simply Connected ◽  
Made In

The theory of inhomogeneous analytic materials is developed. These are materials where the coefficients entering the equations involve analytic functions. Three types of analytic materials are identified. The first two types involve an integer p . If p takes its maximum value, then we have a complete analytic material. Otherwise, it is incomplete analytic material of rank p . For two-dimensional materials, further progress can be made in the identification of analytic materials by using the well-known fact that a 90 ° rotation applied to a divergence-free field in a simply connected domain yields a curl-free field, and this can then be expressed as the gradient of a potential. Other exact results for the fields in inhomogeneous media are reviewed. Also reviewed is the subject of metamaterials, as these materials provide a way of realizing desirable coefficients in the equations.

scholarly journals The solubility of calcium carbonate in tropical sea water

1941 ◽  
Vol 25 (2) ◽  
pp. 235-242 ◽  
Author(s):  
C. L. Smith
Keyword(s):  
Calcium Carbonate ◽  
Solubility Product ◽  
Sea Water ◽  
Natural Conditions ◽  
The West ◽  
Equilibrium Conditions ◽  
Maximum Value ◽  
Andros Island ◽  
Tropical Sea ◽  
Made In

In a previous paper (Smith, 1940b) the chemical changes observed in ocean sea water flowing across the shallow banks on the west coast of Andros Island (Bahamas) were reported. High salinities were produced by evaporation and calcium carbonate was precipitated. From the data obtained under natural conditions a maximum value of the solubility product constant of calcium carbonate in sea water was suggested. There was no reason to believe, however, that this value of the constant represented the true equilibrium conditions, and experiments have since been made in the laboratory with a view to bringing water from these banks into equilibrium with solid calcium carbonate.

scholarly journals On the spectra of isotopes

1920 ◽  
Vol 96 (679) ◽  
pp. 388-395 ◽  
Keyword(s):  
Experimental Error ◽  
Previous Investigation ◽  
Wave Length ◽  
Sixth Order ◽  
Mean Error ◽  
Interference Fringes ◽  
The Mean ◽  
Concave Grating ◽  
Made In

In a previous investigation a comparison was made of a number of lines in the spectra of ordinary lead and of lead of radio-active origin. The wave­-lengths of seven lines in each case were measured from plates taken with a concave grating, and were found to be identical for the two varieties of lead within the limits of experimental error, which was about 0·03 A. A further examination was made in the case of the line λ = 4058 A., which is the brightest line in the spectrum, by measurement of the interference fringes obtained by means of a Fabry and Perot étalon , and it was concluded that any difference between the wave-lengths of this line in the two varieties of lead was less than 0·003 A., which was the mean error in these measurements. Aronberg has recently made a comparison of the wave-length of the line λ = 4058 A. in the spectrum of ordinary lead, and of lead obtained from Australian carnotite, and from measurements made on plates taken in the sixth order of a 10-inch Michelson grating, has found that the wave-length of this line in the spectrum of the lead of radio-active origin is less re­frangible than the line in the spectrum of ordinary lead by 0·0043 A.

scholarly journals THE EFFECT OF ROUGHNESS ON THE MASS-TRANSPORT OF PROGRESSIVE GRAVITY WAVES

1966 ◽  
Vol 1 (10) ◽  
pp. 11 ◽  
Author(s):  
Arthur Brebner ◽  
J.A. Askew ◽  
S.W. Law
Keyword(s):  
Mass Transport ◽  
Gravity Waves ◽  
Orbital Motion ◽  
Wave Length ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Maximum Value ◽  
Transport Velocity ◽  
Mass Transport Velocity ◽  
The Mean

On the basis of non-viscous small amplitude firstorder theory the maximum value of the horizontal orbital motion at the bed in water of constant depth his given by /U/n yy* »* " r •»** */i where k = /L, H is the wave height crest to trough, T is the period, and L the wave length (L = Sry2jr Arf 2*%/L ). On the basis of finite amplitude wave theory where the particle orbits are not closed ana by the insertion of the viscous laminar boundary layer (the conducti6n solution) the mean drift velocity or mass transport velocity on a perfectly smooth bed is given by Longuet- Higgins (1952) as 7, K H* kcr where

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.

The irregular structure of the outer regions of the solar corona

1955 ◽  
Vol 228 (1173) ◽  
pp. 238-251 ◽  
Keyword(s):  
Solar Corona ◽  
Electron Density ◽  
Large Scale ◽  
Wave Length ◽  
Radial Distance ◽  
Radio Interferometer ◽  
Scattering Mechanism ◽  
Irregular Structure ◽  
Made In

The radiation from the radio star in Taurus was recorded on a radio interferometer on occasions when the radiation passed through the outer regions of the solar corona. The recorded intensity was found to decrease rapidly as the radial distance decreased. A series of observations carried out during June 1953 with interferometers of different wave-length and spacing have indicated that the results cannot be explained in terms of absorption, or large-scale refraction effects in the corona. The observations may, however, be accounted for by a scattering mechanism arising from the presence of irregular variations of electron density in the corona. An estimate of the size and electron density of the coronal irregularities is made in the range of distance 5 to 15 R ⦿ . It is suggested that the irregular structure represents an extension of the visible coronal rays.

scholarly journals VIII. Determinations of wave-length from spectra obtained at the total solar eclipses of 1900, 1901 and 1905

1906 ◽  
Vol 206 (402-412) ◽  
pp. 403-452 ◽  
Keyword(s):  
Preliminary Report ◽  
Wave Length ◽  
Royal Observatory ◽  
Solar Eclipses ◽  
Made In

The following paper consists of a discussion of the photographs of the spectra of the chromosphere and corona obtained in three eclipse expeditions from the Royal Observatory, Greenwich. Preliminary reports of the expeditions of 1900 and 1905, where I was one of Sir William Christie’s party, are given in the ‘ Proceedings,’ vol. 67, p. 393, and A, vol. 77, p. 28, and a preliminary report of the expedition to Sumatra in 1901 is given by me in the ‘ Proceedings,’ vol. 69, p. 235. For these eclipse expeditions two spectroscopes were kindly lent by Major Hills, the same spectroscopes he used for photographing the chromosphere and corona at the Indian eclipse of 1898. Deference is made in the preliminary reports to the large amount of assistance received by voluntary helpers in these expeditions; for special assistance in the spectrographic observations I am greatly indebted to Mr. J. J. Atkinson, Mr. Arthur Berry, and Captain Brett. The spectrograms were measured at the Royal Observatory, Greenwich, by Mr. Davidson and myself, and I have profited by Mr. Davidson’s assistance and advice in the preliminary arrangement and adjustments of the spectroscopes as well as in the subsequent measurements and discussion. 1. Details of the observations and of the adjustments of the spectroscopes are given in the ‘ Proceedings,’ vols. 67, 69, and 77. The following is a brief account of the spectrograms of the chromosphere measured :—

scholarly journals Some investigations in röntgen spectra. Part III. -Fine structure of K-absorption edge of SiO 2

1931 ◽  
Vol 131 (818) ◽  
pp. 654-658 ◽  
Keyword(s):  
Fine Structure ◽  
Silicon Oxide ◽  
Wave Length ◽  
High Vacuum ◽  
Short Wave ◽  
X Rays ◽  
Pure Silicon ◽  
Short Wave Length ◽  
Low Dispersion ◽  
Made In

It is now well known from the works of Lindh, Fricke and others that the principal K or L edge is attended on its short wave-length side by a number of secondary edges. The usual method of obtaining this structure consists in putting absorbing screens in the path of X-rays before or after they are analysed by a suitable crystal. The chief difficulty in this is the preparation of absorbing screen of suitable thickness. Fricke as well as Lindh have used this method for the study of absorption spectra of several substances. The former author failed to obtain any K-absorption limit at all for silicon. This was probably due to his using thick absorbing screens coupled with the low dispersion which he obtained with a sugar crystal. Later Lindh succeeded in obtaining K-limits for both silicon and silicon oxide, and showed that as in so many other cases the K-edge of pure silicon is softer than that of the compound. He, however, did not succeed in getting any fine structure. The probable cause of this was again the use of screens of unsatisfactory thickness. This difficulty may be avoided by using the analysing crystal itself as an absorber when a suitable crystal is available. Lindsay and Van Dyke used this method successfully to study the fine structure of the calcium K-edge in calcite, gypsum and fluorite crystals. Nuttall has made partial use of this method in his study of structure of K-absorption edges of potassium and chlorine. Later Lindsay and Voorhees made use of this method to study the fine structure for different crystals containing iron. Following the same method the fine structure for silicon oxide was photographed and measured by using quartz as the analysing and absorbing crystal. The apparatus used was a high vacuum spectrograph of Professor Siegbahn’s design made in the laboratory workshop. Its adjustment and use is described in Part I. The continuous radiation was obtained from a tungsten anticathode formed by dovetailing a plate of this material on the copper anticathode which as already described had four sides.

scholarly journals On the conductivity of a gas, between parallel plate electrodes, when the current approaches the maximum value

1911 ◽  
Vol 86 (583) ◽  
pp. 72-77 ◽  
Keyword(s):  
Atmospheric Pressure ◽  
Parallel Plate ◽  
Complete Solution ◽  
Negative Electrode ◽  
Negative Ions ◽  
Saturation Current ◽  
Maximum Value ◽  
The Difference ◽  
Minimum Force ◽  
Made In

The relation connecting the current with the potential difference between parallel plate electrodes when the gas between the plates has been uniformly ionised by Röntgen rays or Becquerel rays has been investigated theoretically by many physicists. In all cases various assumptions are made in order to simplify the calculations, as the problem becomes very complicated when the disturbance of the field due to the separation of the ions is taken into consideration. Perhaps the most complete solution is that given by Mie, in which the only effect that is neglected is that of diffusion. The difference between the velocities of the positive and negative ions is taken into consideration, and the disturbance of the field due to the charge in the gas produced by the excess of ions of one sign in the neighbourhood of the electrodes. The method of analysis, consisting of a series of approximations, is difficult, but the results have been presented in a convenient form, for currents in air at atmospheric pressure that are certain fractions of the saturation current. A curve is given for each current which shows the distribution of force between the plates. The currents investigated ranged between those that were one-fifth and nine-tenths of the saturation current. In the former case the ratio of the electric force at the negative electrode to the minimum force in the filed was found to be 2.7. The ratio diminishes as the force increases, and for the current that is nine-tenths of the saturation current the ratio becomes 1.39.

scholarly journals FIFTH ORDER GRAVITY WAVE THEORY

2011 ◽  
Vol 1 (7) ◽  
pp. 10 ◽  
Author(s):  
Lars Skjelbreia ◽  
James Hendrickson
Keyword(s):  
Theoretical Calculations ◽  
Wave Length ◽  
Wave Theory ◽  
Order Theory ◽  
Wave Characteristics ◽  
Finite Height ◽  
Scientists And Engineers ◽  
Fifth Order ◽  
Horizontal Bottom ◽  
Made In

In dealing with problems connected with gravity waves, scientists and engineers frequently find it necessary to make lengthy theoretical calculations involving such wave characteristics as wave height, wave length, period, and water depth. Several approximate theoretical expressions have been derived relating the above parameters. Airy, for instance, contributed a very valuable and complete theory for waves traveling over a horizontal bottom in any depth of water. Due to the simplicity of the Airy theory, it is frequently used by engineers. This theory, however, was developed for waves of very small heights and is inaccurate for waves of finite height. Stokes presented a similar solution for waves of finite height by use of trigonometric series. Using five terms in the series, this solution will extend the range covered by the Airy theory to waves of greater steepness. No attempt has been made in this paper to specify the range where the theory is applicable. The coefficients in these series are very complicated and for a numerical problem, the calculations become very tedious. Because of this difficulty, this theory would be very little used by engineers unless the value of the coefficient is presented in tabular form. The purpose of this paper is to present the results of the fifth order theory and values of the various coefficients as a function of the parameter d/L.

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