The secular variation of the geomagnetic field in Egypt in the last 5000 years

The palaeo-intensities (F _a) of the geomagnetic field in Egypt at some ages are determined by archaeomagnetic measurements and found to be:F _a=36.2 T at 3100 B.C., F_a=46.8 T at 3000 B.C.,F _a=36.5 T at 2780 B.C., 49.0 T at 2500 B.C., 36.4 T at 2200 B.C., 57.5 T at 1990 B.C., 62.1 T atca 1400 B.C., 61.5 T at 1400 B.C., 69.9 T at 600 B.C., 59.3 T at 550 B.C., 79.9 T at 460 B.C., 73.7 T at 450 B.C., 69.7 T at 320 B.C., 56.2 T at A.D. 50, 64.9 T, at A.D. 400, 54.4 T at A.D. 300, 57.5 T at A.D. 700 and 43.0 T at A.D. 1975.The palaeo-inclinations (I _a) at some ages are found to be:I _a=24.2° at 420 B.C., 44° at A.D. 50, 60.7° at A.D. 703 and 42° at A.D. 1795.The measured values ofF _a are affected by the anisotropy of magnetic susceptibility of the samples by 13% to 20% of the expected correct value. The suitable correction of this effect is by multiplyingF by 1/((1+0.2(/90)) andF by 1/((1–0.13 (/90)), whereF andF are the resultant values ofF _a if the laboratory field is perpendicular or parallel to the wall of the sample during the Thelliers' experiments, respectively, and is the angle between the direction of natural remnant magnetization of the sample and the direction of the laboratory field.The results of this paper, together with the previous results for Egypt and the neighbourhoods, lead to the production of the secular variation curve of the geomagnetic field in Egypt for the last 5000 years. The intensity of the field shows a periodicity of about 400 years with multiples.     

Quasi-static thermal deformations of a sphere by radiation from a point source

Summary In this paper the quasi-static temperature and stress distributions set up in an elastic sphere by radiation from a point source at a finite distance from the centre of the sphere and out-side it, have been discussed. The temperature boundary condition has been taken in the general form involving an arbitrary function of time. The final solutions have been obtained in terms of series involving Legendre polynomials. Numerical calculations have been done on IBM 1620 Computer and a desk calculator. The results have been represented in graphs.Notation the del operator - u the displacement vector - T the excess of temperature over that at state of zero stress and strain - , Lamé's constants - /2(+) Poisson's ratio - coefficient of linear expansion - 2(1+) - a radius of the sphere - d distance of the point source from the centre of the sphere - d _o a/d - K coefficient of thermal conductivity - h heat transfer coefficient of the surface     

Rayleigh waves in an inhomogeneous medium

Summary Dispersion in Rayleigh waves is discussed for semi-infinite media with = ₁(1 ± cos s z) and = ₁(1 ± cosh s z), being the rigidity of the medium. A few workers tried with the above Fourier type of model but failed to find the dispersive nature. Because they neglected s due to the complexity of the calculation they arrived at a non dispersive frequency equation. This difficulty is removed in this paper and a dispersive frequency equation is obtained which shows both direct and inverse dispersion. The second model leads to non-convergent solution forz but shows many interesting results which are also discussed.     

Rotatory vibration of a thick spherical shell of isotropic non-homogeneous elastic material

Summary Rotatory vibrations of a thick spherical shell of isotropic non-homogeneous material with rigidity and density given by (i) = ₀ r ^-2 withQ =Q ₀ r ^-2 e ^2mr and (ii) = ₀ r ^m with =Q ₀ r ⁿ have been discussed and the frequency equation is derived with numerical enumeration of frequency in each case.     

On the propagation of wave from a cylindrical cavity,II

Summary We have discussed in the paper the disturbance produced in an infinite layer of nonhomogeneous elastic material characterised by = ₀ Z and = ₀ Z where and are the density and shear modulus respectively of the material due to periodic torsional force applied on the wall of a cylindrical hole in the layer. The variation of the displacement component with the depth of the layer is shown graphically and compared with the corresponding homogeneous case.     

Atmosphärische aerosolstreuung im sichtbaren und nahen infrarot

Zusammenfassung Die atmosphärische Aerosolstreuung wird im Bereich 0.52.1 m und 4°40° experimentell untersucht. Sie scheint im Infraroten weitgehend durch die Verhältnisse im Sichtbaren charakterisierbar zu sein, wenn auch die Streudispersion ein unerwartet gegensätzliches Verhalten zeigt. BeiA-ähnlichen, visuellen Streutypen (oder Typen nahe 1) verschwindet diese ab etwa 1.1 m fast vollständig. DieB-ähnlichen, visuellen Streutypen (oder Typen nahe 2) tritt in einem Zwischenbereich (etwa 0.8 bis 1.3 m) starke Streudispersion auf. Für den Gesamtstreutyp wird eine Klassifizierung in Anlehnung an die im Sichtbaren gebräuchliche [11–14]²) vorgeschlagen.

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Summary The scattering by the atmospheric aerosol of radiation in the region 0.52.1 m and 4°40° is investigated experimentally. The features in the infrared can be characterized by that in the visible, but the scattering dispersion is found to be different to that expected. At scattering types nearA (or 1) in the visible there is almost no scattering dispersion for 1.1 m. At types nearB (or 2) in the visible a high scattering dispersion in the region between 0.8 m and 1.3 m was observed. For the whole region of wavelength including the infrared a classification similar to that used in the visible [11–14]²) is suggested.

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Mitteilungen des Astronomischen Instituts der Universität Tübingen Nr. 77     

Flow of non-Newtonian fluid through circular tubes

Summary According to Newton's law of viscosity _y = Dv_y/dy. But experiments have shown that _y is indeed proportional to –dv _x/dy for all gases and for homogeneous nonpolymeric liquids. There are however, a few industrially important materials, e.g. plastics, asphalts, crystalline materials that are not described by the equation given by Newton's law of viscosity and they are referred to as non-Newtonian fluids. The steady state rheological behaviour of most fluids can be expressed by the generalised form, _y = –(dv_y/dy) where may be expressed as a function of eitherdv _x/dy or _y (where is independent of the rate of shear, the behaviour is Newtonian with =). Numerous empirical equations or models have been proposed to express the steady-state relation between _y anddv _x/dy. The flow of Newtonian fluids through circular tubes have been discussed before by many. Here we shall discuss the case of two such models of non-Newtonian fluids through circular tubes. The flow of fluids in circular tubes is encountered frequently in Physics, Chemistry, Biology and Engineering.     

Amplitude Response of a LCR Gravimeter with Feedback at Periods of Microseisms and Earthquake Waves

The amplitude response of a LCR gravimeter with the SRW-E feedback was determined on a vertical vibrating platform. The ink-pen recorder was connected parallel with the digital voltmeter input to obtain an analog response of the gravimeter to the harmonic motion of the base with a peak-to-peak amplitude of 10 m and periods excited in an interval of 4 - 10 s as by the ground motion of meteorological microseisms, and in the interval 10 -100 s as by surface waves of distant strong earthquakes. In the first interval, an unexpected maximum of the amplitude response was observed with the double amplitude of apparent 6,5 Gal (6.5 × 10 _–8 m/s ² ) at a period of 4.8 s, and a baseline shift with the amplitude of–64Gal was observed at the same period. The value of this direct component cannot be separated from the effect of the Earth's gravity field. In the second interval, the amplitude response of the gravimeter displayed one expected maximum at a period of 40 s with the double amplitude of 8.1Gal. At the usual level of microseisms with a peak-to-peak amplitude of up to 2 m the fluctuation of the gravimeter on the direct baseline shifted by –4.9 Gal was estimated at 1 Gal. With typical Rayleigh surface waves with periods of 20 s and double amplitudes of up to 100 m, the fluctuation reached 67 Gal.     

Propagation of surface waves on a nonhomogenous spherically aeolotropic shell

Summary This paper studies the propagation of Surface Waves on a spherically aeolotropic shell surrounded by vacuum. The elastic constantsc _ij and density of the material of the shell are assumed to be of the form _ij r ^l and _o r ^m respectively, where _{ij o} are constants andl, m are any integers.     

Cs137 gamma-ray absorption in eclogites

Summary The coefficient of the gamma-ray absorption _Cs ¹³⁷ investigated in eclogites of the Bohemian Massif varies with fresh samples from0.2477 cm ^–1 to 0.2804 cm ^–1 . Symplectite is the main factor decreasing the value of down to0.242 cm ^–1 . On the contrary, the coefficient increases with the increasing content of clinopyroxene and especially of garnet. The linear dependence of the coefficient on the density may be expressed by the equation =0.0682+0.028.     

Note on the torsional vibration of a thin beam of varying cross-section

Summary In the present note the problem of torsional vibration of a bar in which the moment of inertia and the torsional rigidity are proportional to 0 + 1s, wheres is the spanwise co-ordinate and ₀ and ₁ are real numbers, has been considered.     

On the propagation of wave from a cylindrical cavity

Summary This paper discusses the disturbance produced in an infinite layer of non-homogeneous elastic material characterised by =0 ⁿ and =0ⁿ(n>0) where and are the density and shear modulus respectively of the material, due to periodic torsional force applied on the wall of a cylindrical hole in the layer. The variation of the displacement component with the radius vector is shown graphically and compared with the corresponding homogeneous case.     

Torsional vibration of non-homogeneous isotropic hollow thick cylinder

Summary Free vibration of a thick hollow cylinder of non-homogeneous elastic material having rigidity and density varying according to the laws: (i) =₀(₀+₀ z) and Q=Q₀(Q₀+₀ z) for finite and infinite length of the cylinder and (ii) ₁/r = and Q = ₁/r for finite length only are considered in this paper. Frequency equations are deduced and respective numerical solutions are obtained.     

On the efficiency with which aerosol particles of radius less than 1 μm are collected by columnar ice crystals

A theoretical model is presented which allows computing the efficiency with which aerosol particles of 0.001 r1 m are collected by columnar ice crystals in air of various relative humidities, temperatures, and pressures. Particle capture due to Brownian diffusion, thermo- and diffusiophoresis is considered. It is shown that phoretic effects importantly determine the particle capture process of 0.01r1 m. The various pressure-temperature levels studied are found to affect the collection efficiency only ifr>0.1 m. Comparison shows that water drops generally are better aerosol particle scavengers than columnar ice crystals.     

On the efficiency with which aerosol particles of radius larger than 0.1 μm are collected by simple ice crystal plates

A theoretical model is presented which allows computing the efficiency with which aerosol particles of radius 0.1r10 m are collected by simple ice crystal plates of radius 50a _c 640 m in air of various relative humidities, temperatures and pressures. Particle capture due to thermophoresis, diffusiophoresis and inertial impaction are considered. It is shown that the capture efficiency of an ice crystal in considerably affected by phoretic effects in the range 0.1r1 m. For aerosol particles ofr>1 m the efficiency is strongly controlled by the flow field around the crystal and the density of the aerosol material. Trajectory analysis also predicts that aerosol particles are preferentially captured by the ice crystal rim. Our theoretica results are found to agree satisfactorily with the laboratory studies presently available. Comparison shows that for the same pressure, temperature and relative humidity of the ambient air ice crystal plates are better aerosol particle scavengers than water drops.     

Uniform heat flow in a semi-infinite medium disturbed by a body of different thermal conductivity

Summary The approximate solution for the disturbance of a uniform heat flow in a homogeneous semi-infinite medium by an object of different thermal conductivity buried in it is generally used in the interpretation of heat flow anomalies on the ocean bottom. In order to know the accuracy of the approximate solution, a comparison between the approximate solution and the exact solution is given in the case of a very long horizontal cylinder in a semi-infinite medium. The computed results indicate that the two solutions agree to within 10% whend>1.3 and 0.5<<2, whered is ratio of the depth to the radiusR ₀ of the cylinder and is the factor of the contrast of the thermal conductivities between the medium and the body. As for the cases when 1 and 1, the same accuracy can be obtained only whend>2. A similar approach is also applied to the case of a spherical conductor in a semi-infinite medium by using a bispherical harmonic solution. The results of both the bipolar solution and the bispherical solution show that when 1 andd1, the vertical thermal gradient at the surface of the semi-infinite medium is always positive and tends to zero, but a negative vertical gradient may be obtained for the approximate solutions.     

Waves in an elastic plate with an irregular boundary

Summary Green's function corresponding to the displacements for anSH-line source inside a wedge shaped medium finite or infinite in which the density and the elastic parameter are not constant throughout but some class of function ofr, the radial distance (i.e. and satisfy some differential equation) has been obtained. The paths of propagation of the cylindrical waves, their reflections on different boundaries and their continuous refractions within the medium has been clearly established. The scattered field from the different parts of the body have been pointed out with prescribed distribution of and in this inhomogeneous wedge. It is shown that for some distribution of and the rays are curved and the reflections at the two plane boundaries occur in such a way that no ray will go to infinity by reflection, rather they are coming back towards the apex after suitable number of reflections with variable intensity. Also there are some distributions of and in the same class as mentioned earlier, such that the behaviour of the waves is similar to that in a homogeneous wedge, i.e. these waves will go to infinity by a suitable number of reflections and ultimately die out. The first case is quite unlike the usual homogeneous medium with non parallel boundaries and so care must be taken in computing the field within the nonhomogeneous medium within the non-parallel boundaries.     

On the possibility of utilizing grid reports in a local model of short-range forecast of meteorological elements

Summary In the experiment described, we test the possibility of utilizing forecasts of the pressure field, contained in GRID reports, to solve the problem of horizontal boundary conditions of a local model of short-range forecast of meteorological elements. We prove that the assumption of a linear tendency of the prognostic variables in the boundary region yields good results, using the Perkey-Kreitzberg method[1], even if applied to period T=24 hrs. In the Perkey-Kreitzberg method the effect of the horizontal diffusion in the boundary region is suppressed[2]. However, considering the diffusive term apart from the procedure of the method mentioned proves detrimental to the forecast.

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Water uptake and equilibrium sizes of aerosol particles at high relative humidities: Their dependence on the composition of the water-soluble material

Equilibrium water uptake and the sizes of atmospheric aerosol particles have for the first time been determined for high relative humidities, i.e., for humidities above 95 percent, as a function of the particles chemical composition. For that purpose a new treatment of the osmotic coefficient has been developed and experimentally confirmed. It is shown that the equilibrium water uptake and the equilibrium sizes of atmospheric aerosol particles at large relative humidities are significantly dependent on their chemical composition.List of symbols A proportionality factor - a _w activity of water in a solution - c _{p v} specific heat of water vapour at constant pressure - c _w specific heat of liquid water - f relative humidity - l _w specific heat of evaporation of water - M _i molar mass of solute speciesi - M _s mean molar mass of all the solute species in a solution - M _w molar mass of water - m ₀ mass of an aerosol particle in dry state - m _i mass of solute speciesi - m _s mass of solute - m _w mass of water taken up by an aerosol particle in equilibrium state - m total molality=number of mols of solute species in 1000 g of water - m _i molality of solute speciesi - m _k total molality of a pure electrolytek - O(m ²) remaining terms being of the second and of higher powers ofm - p ⁺ standard pressure - p total pressure of the gas phase - p pressure within a droplet - p ₁,p ₂,p ₃ coefficients in the expansion of M - p _1i, p_2i, p_3i specific parameters of ioni - p _s saturation vapour pressure - p _w water vapour pressure - R _w individual gas constant of water - r radius of a droplet - r ₀ equivalent volume radius of an aerosol particle in dry state - T temperature - T ₀ standard temperature - T ₁ temperature of the pure water drop in the osmometer - v _w specific volume of pure water - z _i valence of ioni - _i relativenumber concentration of ioni in a solution - correction term due to the adsorption of ions at liquid-solid interfaces - activity coefficient of solute speciesi in a solution, related to molalities - I bridge current - T temperature difference between solution and pure water drop in the osmometer - exponential mass increase coefficient - _w specific chemical potential of water vapour - _w specific chemical potential of water - ⁰ _w specific chemical potential of pure water vapour - ⁰ _w specific chemical potential of pure water - ₀ density of an aerosol particle in dry state - _w density of pure water - surface tension of a droplet - ₀ surface tension of pure water, i.e., at infinite dilution of the solute - osmotic coefficient - _k osmotic coefficient of a solution of a pure electrolytek - _k osmotic coefficient of a solution of a mixed solute - _M fugacity coefficient of water vapour - ^s _{i=1 i} z ² _i This work is part of a Ph.D. thesis carried out at the Meteorological Institute of the Johannes Gutenberg-Universität, Mainz.     

Détermination des paramètres d'Ångström par des observations actionmétriques courantes

Summary By comparing the equalities expressing the solar flux within a wide spectral region on the assumption of an extintion within the atmospheric aerosol given by ^– and that of an extintion represented by ₁^–1, a relationship is established by means of which: 1) The error is discussed which is done when the air opacity is expressed by ₁, in the case when 1; 2) A simple and quick method is worked out for determining the parameters and from actinometric observations, carried out within the spectral regions <525 m and 525 m<<625 m.