THE EQUATION OF MOTION OF A GEOPHONE ON THE SURFACE OF AN ELASTIC EARTH

Geophysics ◽  
1944 ◽  
Vol 9 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Alfred Wolf
Keyword(s):  
Wave Length ◽  
Elastic Solid ◽  
Damping Force ◽  
High Frequencies ◽  
Elastic Earth ◽  
Linear Dimensions ◽  
The Earth ◽  
Restoring Forces ◽  
System Equations

The motion of a geophone case placed on the surface of an elastic earth does not follow faithfully the motion of the earth at high frequencies. In effect, a weight placed on the surface of an elastic solid constitutes a damped oscillating system. The elastic restoring forces are determined by the area of contact between the weight and the surface of the solid and by the elastic moduli of the solid. The damping force is due to emission of elastic waves by the oscillating weight. The motion of the solid also contributes to the inertia of the system. Equations are developed for these forces on the assumption that the wave length is long compared to the linear dimensions of the area of contact between the weight and the elastic solid. This leads to a determination of the frequency of oscillation and of the decrement of such a system.

scholarly journals On seismic waves in a visco-elastic earth

1923 ◽  
Vol 104 (725) ◽  
pp. 271-278 ◽  
Keyword(s):  
Wave Propagation ◽  
Seismic Waves ◽  
Equations Of Motion ◽  
Elastic Solid ◽  
Theory Of Elasticity ◽  
Alternative Procedure ◽  
Stress Strain ◽  
Elastic Earth ◽  
The Earth ◽  
Modified Equations

Experiments have shown that the rocks which form the outermost crust of the Earth differ in their behaviour under stress from that of an ideal elastic solid, one of the more important departures being the possession of “ viscous ” properties. Galitzin, Nagaoka and Rudski have proposed to take account of viscosity by adding a “ frictional ” term or terms to the equations of motion of the ordinary theory of elasticity, and have applied the modified equations to problems of seismology. An alternative procedure is to assume some stress-strain-time law, and from this to deduce the laws of wave-propagation.

scholarly journals A new apparatus for determining the relationship between wave-lengths of light and the fundamental standards of length

1933 ◽  
Vol 231 (694-706) ◽  
pp. 75-145 ◽  
Keyword(s):  
Wave Length ◽  
Weights And Measures ◽  
The Earth ◽  
New Apparatus ◽  
Specific Proposal ◽  
Unit Of Length ◽  
The Relationship ◽  
Fundamental Units ◽  
Red Radiation

The idea of establishing the fundamental units of length on a basis defined by some natural standard has long attracted physicists. The metre was originally intended to represent one ten-millionth of a meridional quadrant of the earth,* and the Weights and Measures Act of 1824 prescribed that the yard, if ever lost or destroyed, should be replaced by reference to the length of a pendulum beating seconds in vacuum at sea level in London. It is believed that BABINET, in 1829, suggested the use of a wave-length of light to define the fundamental unit of length. The first specific proposal to correlate the wave-length of light with material standards of length was made about 1875 by GOULD, who suggested the use of a diffraction grating for the determination. It was not until 1893 that the first direct measurement of the metre in terms of the red radiation of cadmium was made by MICHELSON and BENOÎT. § The comparison was made possible by a slightly modified form of the famous interferometer which MICHELSON had devised originally for the attempt to measure the relative velocity of the earth through the ether. In 1906, BENOÎT, FABRY and Perot repeated the determination of the length of the metre in terms of the red radiation of cadmium, using different methods and apparatus. More recently, in 1928, WATANABE and IMAIZUMI have again repeated the determination with apparatus essentially the same as that used by BENOÎT, FABRY and PEROT.

HADIS KURAIB DALAM KONSEP RUKYATUL HILAL

1970 ◽  
Vol 13 (2) ◽  
Author(s):  
Muslih Husein
Keyword(s):  
The West ◽  
The Earth ◽  
New Moon ◽  
The Republic

Hisab dan rukyat, hakikatnya, adalah cara untuk mengetahui pergantian bulan. Kajian ini memperlihatkan beberapa temuan. Pertama, korelasi antara hadis Kuraib dan terjadinya perbedaan penetapan awal Ramadan, Syawal, dan Dzul Hijjah di Indonesia. Kementerian Agama Republik Indonesia telah menetapkan bahwa Indonesia secara keseluruhan menjadi satu wilayah hukum (wilayatul hukmi). Kedua, tentang keberhasilan rukyat al-hilal di satu kawasan yang diberlakukan bagi kawasan lain di muka bumi. Perlu diketahui bersama bahwa visibilitas pertama hilal tidak meliputi seluruh muka bumi pada hari yang sama, melainkan membelahnya menjadi dua bagian: (1) bagian sebelah Barat yang dapat melihat hilal dan (2) bagian sebelah Timur yang tidak dapat melihat hilal.Hisab and rukyat is a way to know the turn of the month. This study shows several findings. First is the correlation between Kuraib traditions and differences in the determination of the beginning of Ramadan, Shawwal, and Dhul-Hijjah in Indonesia. Ministry of Religious Affairs of the Republic of Indonesia has stated that Indonesia as a whole into a single jurisdiction (wilayatul hukmi). Second, on the success rukyat alhilal in one area that applied to other regions of earth. Important to know that the first visibility of the new moon does not cover the entire face of the earth on the same day, but splitting it into two parts: (1) part of the West to see the new moon, and (2) part of the East were not able to see the new moon.

Forecasting the fl ood situation using space images in the city of Tavda Sverdlovsk region

2018 ◽  
Vol 934 (4) ◽  
pp. 46-52
Author(s):  
A.S. Bruskova ◽  
T.I. Levitskaya ◽  
D.M. Haydukova
Keyword(s):  
Water Levels ◽  
Economic Damage ◽  
Geoinformation System ◽  
Space Images ◽  
Geoinformation Systems ◽  
Emergency Situations ◽  
The Earth ◽  
Maximum Water ◽  
The City

Flooding is a dangerous phenomenon, causing emergency situations and causing material damage, capable of damaging health, and even death of people. To reduce the risk and economic damage from flooding, it is necessary to forecast flooding areas. An effective method of forecasting emergency situations due to flooding is the method of remote sensing of the Earth with integration into geoinformation systems. With the help of satellite imagery, a model of flooding was determined based on the example of Tavda, the Sverdlovsk Region. Space images are loaded into the geoinformation system and on their basis a series of thematic layers is created, which contains information about the zones of possible flooding at given water level marks. The determination of the area of flooding is based on the calculation of the availability of maximum water levels at hydrological stations. According to the calculated security data, for each hydrological post, flood zones are constructed by interpolation between pre-calculated flood zones of standard security. The results of the work can be used by the Main Directorate of the Ministry for Emergency Situations of Russia for the Sverdlovsk Region.

scholarly journals Thermal Stresses in Chemically Hardening Elastic Media With Application to the Molding Process

1974 ◽  
Vol 41 (3) ◽  
pp. 647-651 ◽  
Author(s):  
Myron Levitsky ◽  
Bernard W. Shaffer
Keyword(s):  
Residual Stress ◽  
Chemical Reaction ◽  
Thermal Stresses ◽  
Stress Component ◽  
Elastic Solid ◽  
Molding Process ◽  
Hardening Process ◽  
Exothermic Chemical Reaction ◽  
Component Parallel

A method has been formulated for the determination of thermal stresses in materials which harden in the presence of an exothermic chemical reaction. Hardening is described by the transformation of the material from an inviscid liquid-like state into an elastic solid, where intermediate states consist of a mixture of the two, in a ratio which is determined by the degree of chemical reaction. The method is illustrated in terms of an infinite slab cast between two rigid mold surfaces. It is found that the stress component normal to the slab surfaces vanishes in the residual state, so that removal of the slab from the mold leaves the remaining residual stress unchanged. On the other hand, the residual stress component parallel to the slab surfaces does not vanish. Its distribution is described as a function of the parameters of the hardening process.

scholarly journals Determination of underground voids in the surface of the earth section

2021 ◽  
Vol 1942 (1) ◽  
pp. 012085
Author(s):  
G A Pchelkin ◽  
A S Grevtseva ◽  
M V Diuldin
Keyword(s):  
The Earth
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