2,107 research outputs found
Some Notes on the Interpretation of Rapid Fluctuations in Earth-Currents Observed in High Latitudes
[PREFACE]
This report was prepared as a part of the Interdisciplinary
study of the upper atmospheric disturbance in the polar regions
that is conducted at the Geophysical Institute under Dr, C. T. Elvey,
Director of the Institute. The report is primarily intended for
the student of geophysics who is interested in this subject. A
part of the mathematical procedure that was previously given by
Prof. A. T. Price (reference 9 in end of paper) is included in
Sections 4 to 6 with some modifications so as to enable the student
to follow, without referring to Prof. Price’s paper, the derivation
of the formulae which are used in the present discussion* and to
apply the method to similar problems.
November 15, 1958 M. S.This paper shows that a periodically varying infinite linear
current, or a periodically varying turbulent circular current of
small radius (here approximated by a magnetic dipole with a changing
dipole moment), in the ionosphere, which will give rise to magnetic
variations of observed order of magnitude, is adequate for producing
voltage differences in the ground of order 0 .1 to 1 volt per kilometer
that are frequently observed in high latitudes during disturbed
periods. It appears difficult to interpret the earth-current
record in terms of its primary origin, unless the distribution
of the perturbing magnetic field and that of electric conductivity
of the earth are both adequately known. However, the earth-current
record is a good indicator of the upper atmospheric disturbance in
the polar regions.Ye
A Note on Harmonic Analysis of Geophysical Data with Special Reference to the Analysis of Geomagnetic Storms
Some geophysical characteristics tend to have a fixed
distribution relative to the sun. An example is the distribution
of air temperature on an ideal earth that is perfectly symmetrical
(e.g., in its pattern of land and water) about its axis
of rotation. In such a case the geophysical characteristic
at any fixed station on the earth undergoes a daily variation
that depends only on local time (and latitude and season). This
simple pattern of daily change may be modified by intrinsic
changes in the solar influences on the earth. The harmonic
components of the daily variation at any station may in this
case undergo phase changes, in some respects corresponding to
Doppler shifts of frequency in optical or sonic phenomena.
Care is then needed if the results of harmonic analysis are to
be properly interpreted. Such interpretation is discussed with
reference to the parts Dst and DS of the magnetic storm
variations.
Like caution must be observed in cases where the amplitude
of a harmonic variation changes,with fixed phase.Scientific Report No. 1 -- Contract No. AF 19(6o4)-2l63 April 18, I960 -- Geophysics Research Directorate Air Force Cambridge Research Center Air Research and Development Command United States Air Force Bedford, MassachusettsYe
Th�nen and the New Economic Geography
In this paper, I explain Th�nen's pioneering work on industrial agglomeration. In my opinion, Th�nen's thinking on industrial agglomeration was not only amazingly advanced for his time, but in many respects remains novel even today. It is shown that if we unify Th�nen's well-known theory on agricultural land use with this pioneering work on industrial agglomeration by using modern tools, then we essentially come up with a prototype of New Economic Geography model.
A Study of the Morphology of Magnetic Storms Great Magnetic Storms
Average characteristics are determined for 74 great magnetic storms
with sudden commencements that occurred in 1902-1945. The storm field is
resolved for different epochs of storm time into tv;o parts: (i) Dst, which
is independent of local time, that is, of longitude A, relative to the sun,
and (ii) DS, which depends on A . They are obtained, for each of the three
magnetic elements, declination, horizontal force, and vertical force, at
eight geomagnetic latitudes ranging from 80°N to 1°S. DS is harmonically
analyzed; the first harmonic component is shown to be the main component of
DS. The storm-time course of this component is compared with that of Dst;
DS attains its maximum earlier and decays more rapidly. The results of the
analysis of great storms are compared with those for weak and moderate
storms that were reported previously. Some characteristics of Dst change
with intensity. Except in magnitude, main characteristics of DS are independent
of intensity.The research reported in the document has been sponsored
by the Air Force Cambridge Research Center, Air Research
and Development Command, under Contract No. AF 19(604)-2163.LIST OF TABLES -- LIST OF FIGURES -- ABSTRACT -- 1. INTRODUCTION -- 2. OBSERVATORIES -- 3. STORM-TIME VARIATIONS : 3.1 Dst in the geomagnetic-north component, Hgm ; 3.2 Dst in the geomagnetic-east component, Egm ; 3.3 Dst in the vertical force Z -- 4. DISTURBANCE DAILY VARIATIONS -- 5. FIRST HARMONIC COMPONENT OF DS -- 6 . HIGHER HARMONIC COMPONENTS OF DS AND SD -- 7. COMPARISON OF Dst AND DS -- 8 . SEASONAL VARIATIONS IN Dst : 8.1 Seasonal variation in Dst(H); season d and season j ; 8.2 Seasonal variation in Dst(H); season e and season s -- 9. SEASONAL VARIATIONS IN DS -- 10. CONCLUSION -- 11. ACKNOWLEDGEMENTS -- REFERENCESYe
A Study of the Morphology of Magnetic Storms: Moderate Magnetic Storms
Some average characteristics are determined for 136 moderate magnetic
storms with sudden commencements that occurred during the interval
1902-1945. The average storm field is resolved for different
epochs of storm time st into Dst, independent of local time, that is, of
longitude X , relative to the sun, and into DS, that depends on X , Part
DS is expressed in terms of harmonic components with respect to X ,
and like Dst, the amplitudes and phases of these components, are functions
of st and of geomagnetic latitude. They are determined, for each
of the three magnetic elements, declination, horizontal force, and vertical
force, at eight geomagnetic latitudes ranging from 80*N to 1°S. In
the first, and main harmonic component of DS, its variations with respect
to storm time differs notably from that of Dst: its maximum is
attained earlier and its decay is more rapid. The storm -time changes
of the smaller harmonic components of DS have been less fully determined.
The average characteristics of moderate storms are compared
with those of weak storms.The research reported in the document has been sponsored by
the Air Force Cambridge Research Center, Air Research and
Development Command, under Contract No, AF 19(604)-1732.
AF 19(604)-1732
AFCRC-TR-57-295
AD 117-256LIST OF TABLES -- LIST OF FIGURES -- ABSTRACT -- 1. INTRODUCTION -- 2. THE OBSERVATORIES -- 3. THE STORM-TIME VARIATIONS : 3.1 Dst in the Geomagnetic-North Component, Hgm ; 3.2 Dst in the Geomagnetic-East Component, Egm ; 3.3 Dst in the Vertical Force -- 4. THE DISTURBANCE DAILY VARIATIONS -- 5. THE FIRST COMPONENT OF DS -- 6 „ THE HIGHER HARMONIC COMPONENTS OF DS AND SD -- 7. COMPARISON OF Dst AND DS -- 8 „ CONCLUSION : 8.1 The Intensity Index of Magnetic Storms ; 8.2 The Dst Variations ; 8.3 The DS and SD Variations ; 8.4 Future Plans -- 9. ACKNOWLEDGEMENTS -- REFERENCESYe
Error estimates of a stabilized Lagrange-Galerkin scheme for the Navier-Stokes equations
Error estimates with optimal convergence orders are proved for a stabilized
Lagrange-Galerkin scheme for the Navier-Stokes equations. The scheme is a
combination of Lagrange-Galerkin method and Brezzi-Pitkaranta's stabilization
method. It maintains the advantages of both methods; (i) It is robust for
convection-dominated problems and the system of linear equations to be solved
is symmetric. (ii) Since the P1 finite element is employed for both velocity
and pressure, the number of degrees of freedom is much smaller than that of
other typical elements for the equations, e.g., P2/P1. Therefore, the scheme is
efficient especially for three-dimensional problems. The theoretical
convergence orders are recognized numerically by two- and three-dimensional
computations
The Dynamics of Knowledge Diversity and Economic Growth
How is long run economic growth related to the endogenous diversity of knowledge? We formulate and study a microeconomic model of knowledge creation, through the interactions among a group of heterogeneous R & D workers, embedded in a growth model to address this question. In contrast with the traditional literature, in our model the composition of the research work force in terms of knowledge heterogeneity matters, in addition to its size, in determining the production of new knowledge. Moreover, the heterogeneity of the work force is endogenous. Income to these workers accrues as patent income, whereas transmission of newly created knowledge to all such workers occurs due to public transmission of patent information. Knowledge in common is required for communication, but differential knowledge is useful to bring originality to the endeavor. Whether or not the system reaches the most productive state depends on the strength of the public knowledge transmission technology. Equilibrium paths are found analytically. Long run economic growth is positively related to both the effectiveness of pairwise R & D worker interaction and to the effectiveness of public knowledge transmission.knowledge creation; knowledge externalities; microfoundations of endogenous growth; knowledge diversity and growth
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