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1.
Summary In this paper the generalized thermoelastic longitudinal waves and the temperature field set up due to coupling of the displacement and the temperature fields, with heat wave travelling with certain finite velocity, in an unbounded medium are studied. The thermoelastic displacement potential and the temperature field at any point are obtained in terms of the surface integrals involving the potential, the temperature and their normal derivatives.Notation
x
i
the cartesian coordinate system,i=1,2,3
-
n
(u
i) the displacement vector
-
(/x
i) the del operator
- t
/t the derivative with respect to time
-
T
o
the temperature corresponding to the natural stat of zero stress and strain
-
T
Absolute temperature
-
c
e
the specific heat
- ,
Lamé's constants
- 0
the density
-
coefficient of linear thermal expansion
-
K
thermal conductivity coefficient
- kk
u
- 0
the relaxation time 相似文献
2.
Summary Approximate expressions for the Hilbert transform of the functionf(t)=exp(-
0
2
t
2/2) cos(
0
t+v) are determined. This function, given a suitable choice of the three parameters 0, and v, approximates a wide class of seismic signals very well. The approximate expressions for the Hilbert transform enable very simple formulae to be given for the elementary seismograms of the individual seismic body waves (in the zero approximation of the ray theory). This accelerates the computation of ray theoretical seismograms considerably. 相似文献
3.
A daily rainfall occurrence process 总被引：1，自引：0，他引：1
A model for the periodic (annual cycle), discrete rainfall occurrence process is presented. Using this model the probabilistic properties of the process in -day intervals can be investigated. In such an interval the rainfall occurrence process is approximated by some stationary processa
t
,tIN. The processa
t
,tIN is described by the distributions of the lengths of wet and dry sequences. It is assumed that the lengths of successive wet and dry sequences are independent. For this process the distribution of the number of wet days in -day intervals is calculated. The model is fitted to 50-year rainfall data from Wroclaw, Poland. Rainfall amounts of 0.1, 1.0 and 2.0 mm are considered as thresholds defining a wet day. To estimate the distribution of the length of wet and dry sequences the family of Pascal distribution is chosen. 相似文献
4.
We estimate (/T)
P
of the lower mantle at seismic frequencies using two distinct approaches by combining ambient laboratory measurements on lower mantle minerals with seismic data. In the first approach, an upper bound is estimated for |(/T)
P
| by comparing the shear modulus () profile of PREM with laboratory room-temperature data of extrapolated to high pressures. The second approach employs a seismic tomography constraint ( lnV
S
/ lnV
P
)
P
=1.8–2, which directly relates (/T)
P
with (K
S
/T)
P
. An average (K
S
/T)
P
can be obtained by comparing the well-established room-temperature compression data for lower mantle minerals with theK
S
profile of PREM along several possible adiabats. Both (K
S
/T) and (/T) depend on silicon content [or (Mg+Fe)/Sil of the model. For various compositions, the two approaches predict rather distinct (/T)
P
vs. (K
S
/T)
P
curves, which intersect at a composition similar to pyrolite with (/T)
P
=–0.02 to –0.035 and (K
S
/T)
P
=–0.015 to –0.020 GPa/K. The pure perovskite model, on the other hand, yields grossly inconsistent results using the two approaches. We conclude that both vertical and lateral variations in seismic velocities are consistent with variation due to pressure, temperature, and phase transformations of a uniform composition. Additional physical properties of a pyrolite lower mantle are further predicted. Lateral temperature variations are predicted to be about 100–250 K, and the ratio of ( lnp/ lnV
S
)
P
around 0.13 and 0.26. All of these parameters increase slightly with depth if the ratio of ( lnV
S
/ lnV
P
)
P
remains constant throughout the lower mantle. These predicted values are in excellent agreement with geodynamic analyses, in which the ratios ( ln / lnV
S
)
P
and ( / lnV
S
)
P
are free parameters arbitrarily adjusted to fit the tomography and geoid data. 相似文献
5.
I. V. Radhakrishna Murthy 《Pure and Applied Geophysics》1985,123(2):232-238
The horizontal and vertical derivative profiles of magnetic anomalies of dykes show some interesting properties. The points of zero derivatives and the points where the derivatives are equal are conjugate point pairs. A method of interpretation of dyke anomalies is suggested, which utilizes the distances between these points.Notation
F
Magnetic anomaly in total intensity
-
Z
Depth to top of the dyke
- 2T
Width of the dyke
-
Geological dip of the dyke
-
I
Effective intensity of magnetisation in the plane of profile
-
Dip of effective magnetisation vector in the plane of profile
-
Strike angle of the dyke
-
i
Magnetic dip
-
Q
–
-
Q
f
–+arctan (sin coti)
-
I
f
相似文献
6.
A numerical study has been made of the heat transfer through a fluid layer with recirculating flow. The outer fluid surface was assumed to be spherical, while the inner surface consisted of a sphere concentrically or eccentrically located with respect to the outer spherical surface. The recirculating flow was assumed to be driven by a gas flow creating stress on the fluid's outer surface so that creeping (low Reynolds number) flow developed in its interior. The present study solves the Stokes equation of motion and the convective diffusion equation in bispherical coordinates and presents the streamline and isotherm patterns.Nomenclature
a
i
inner sphere radius
-
a
d
outer sphere radius
-
A
1
defined by equation (5)
-
A
2
defined by equation (6)
-
B
1
defined by equation (7)
-
B
2
defined by equation (8)
-
c
dimensional factor for bispherical coordinates
-
C
constant in equation (4)
-
d
narrowest distance between the two eccentric spheres
-
E
2
operator defined by equation (1) in spherical coordinates and by equation (21) in bispherical coordinates
-
G
modified vorticity, defined in equation (22)
-
G
*
non-dimensional modified vorticity, defined in equation (28)
-
h
metric coefficient of bispherical coordinate system, defined in equation (18)
-
k
w
thermal conductivity of water
-
K
1
defined by equation (9)
-
K
2
defined by equation (10)
-
N
Re
Reynolds number=2a
dU/gn
-
N
Pe,h
Peclet number=2a
dU/
-
n
integer counter
-
q
heat flux
-
r
radius
-
r
*
non-dimensional radius=r/a
d
-
S
surface area
-
t
time
-
t
*
non-dimensional time=t/a
d
2
-
T
temperature
-
T
o
temperature at inner sphere surface
-
T
a
temperature at outer sphere surface
-
T
*
non-dimensional temperature;=(T–T
o)/(Ta–To)
-
u
velocity
-
u
r
radial velocity in spherical coordinates
-
u
angular velocity in spherical coordinates
-
u
radial velocity in bispherical coordinates
-
u
angular velocity in bispherical coordinates
-
U
free stream velocity
-
u
r
*
=u
r/U
-
u
*
=u
/U
-
u
*
=u
/U
-
u
*
=u
/U
Greek symbols a
1
small displacement
-
vorticity, defined in equation (17)
- *
non-dimensional vorticity, defined in equation (27)
-
radial bispherical coordinates
- o
bispherical coordinate of inner sphere
- a
bispherical coordinate of outer sphere
-
angular coordinate in spherical coordinates
-
thermal diffusivity
- w
thermal diffusivity of water
-
kinematic viscosity
-
angular bispherical coordinate
-
spherical coordinate
-
streamfunction
-
non-dimensional streamfunction for spherical coordinates, = /(U
a
d
2
)
- *
non-dimensional streamfunction for bispherical coordinates, defined in equation (26) 相似文献
7.
Summary The geopotential scale factor R
0
=GM/W
0
has been determined on the basis of satellite altimetry as R
0=(6 363 672·5±0·3) m and/or the geopotential value on the geoid W
0
=(62 636 256·5±3) m
2
s
–2
. It has been stated that R
0
and/or W
0
is independent of the tidal distortion of surface W=W
0
due to the zero frequency tide.
¶rt;a nmu amumuu u ama amnmuaa R 0 =GM/W 0 =(6 363 672,5±0,3) m u/uu aunmuaa a nmuu¶rt;a W 0 =(62 636 256,5±3) m2 s–2. m, m R 0 u/uu W 0 auum m nm amu a a nuu ¶rt;au nmu W=W 0 .相似文献
8.
Summary A general analytical model for travel times of seismic waves propagating in a radially asymmetric Earth, is suggested. It is represented by a series of irreducible spherical tensor products with bipolar spherical coefficients. The main term of the series describes the travel times in a radially symmetric Earth, the others represent corrections due to the spherical assymmetry. The method of least squares is suggested for determining the bipolar spherical coefficients from observed seismic travel times. Since the proposed theory assumes that the analytical representation is related to the reference earth, the corrections to the non-zero focal depth and non-zero sea-level height of the seismographic station must be introduced.
aamuam a aaumua ¶rt; ¶rt;¶rt;aa uu a¶rt;ua ¶rt;¶rt; . mm¶rt;a aam u¶rt; ¶rt;a n¶rt;u m unu uuu uumau. ¶rt;a nuam¶rt;a a¶rt;ua ¶rt;¶rt; . ¶rt;u m aam nna a m a¶rt;ua ¶rt;¶rt;mu. ¶rt;aam un uu uum ¶rt; a¶rt;a¶rt;aa a¶rt;um m¶rt; auu a¶rt;am. ¶rt;aaa mu u¶rt;um u n¶rt;nu -unu¶rt;a u. nuam n ¶rt;u nna n¶rt;mau¶rt;aa, a uu aa u m nm a¶rt;u.相似文献
9.
Source characteristics of the 1992 Nicaragua tsunami earthquake inferred from teleseismic body waves
We analyzed the broadband body waves of the 1992 Nicaragua earthquake to determine the nature of rupture. The rupture propagation was represented by the distribution of point sources with moment-rate functions at 9 grid points with uniform spacing of 20 km along the fault strike. The moment-rate functions were then parameterized, and the parameters were determined with the least squares method with some constraints. The centroid times of the individual moment-rate functions indicate slow and smooth rupture propagation at a velocity of 1.5 km/s toward NW and 1.0 km/s toward SE. Including a small initial break which precedes the main rupture by about 10 s, we obtained a total source duration of 110 s. The total seismic moment isM
o
=3.4×1020 Nm, which is consistent with the value determined from long-period surface waves,M
o
=3.7×1020 Nm. The average rise time of dislocation is determined to be 10 s. The major moment release occurred along a fault length of 160 km. With the assumption of a fault widthW=50 km, we obtained the dislocationD=1.3 m. From andD the dislocation velocity isD=D/0.1 m/s, significantly smaller than the typical value for ordinary earthquakes. The stress drop =1.1 MPa is also less than the typical value for subduction zone earthquakes by a factor of 2–3. On the other hand, the apparent stress defined by 2E
s
/M
o
, where andE
s
are respectively the rigidity and the seismic wave energy, is 0.037 MPa, more than an order of magnitude smaller than . The Nicaragua tsunami earthquake is characterized by the following three properties: 1) slow rupture propagation; 2) smooth rupture; 3) slow dislocation motion. 相似文献
10.
Radan Huth 《Studia Geophysica et Geodaetica》1992,36(3):280-292
Summary One of the important atmospheric levels, the mean energetic level (MEL), which in a sense reflects the energetics of the whole atmosphere, is defined. Its fundamental properties are shown. In order to describe the MEL correctly a new vertical coordinate is introduced and discussed. The new coordinate, , is defined as the ratio of height and temperature. The MEL is shown to be a level with constant value of . Some incorrect conclusions concerning the MEL, derived in the past, have been corrected.List of symbols used
c
p
specific heat of air at constant pressure
-
c
v
specific heat of air at constant volume
-
e
base of natural logarithms
-
E
total potential energy
-
f
Coriolis parameter
-
g
acceleration of gravity
-
i
specific internal energy
-
I
internal energy
-
J
enthalpy
-
k
unit vector pointing upwards
-
p
pressure
-
Q
diabatic heating rate
-
R
gas constant of the air
-
t
time
-
T
temperature
-
v
horizontal velocity
-
v
(3)
three-dimensional velocity
-
w
vertical velocity in thez-system
-
z
height
-
temperature growth rate (T/z)
-
Pechala's vertical coordinate (z/T)
-
generalized vertical velocity in the -system (d/dt)
-
specific potential energy
-
potential energy
-
density of the air
-
Ruppert function
-
T(1–)–1
- ( )
S
quantity at the sea level
- ( )*
quantity at the MEL 相似文献
11.
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.
nua num n m unau n n ¶rt;au, ¶rt;au ¶rt; ¶rt; u numaau u a ¶rt;u am na muu m. aam, m n¶rt;nu u m¶rt;uu nmuu n au amu nu unauu m¶rt;a u- [1] ¶rt;am u mam ¶rt;a nu nuuu nu¶rt; T=24 a. m¶rt; u- nu¶rt;um n¶rt;au uuuma ¶rt;uuu au amu[2]. ama ¶rt;u a n¶rt; nu¶rt; m¶rt;a nu¶rt;um, ¶rt;a, ¶rt;u n.相似文献
12.
Summary The purpose of this study was to determine to what extent the effect of interplanetary parameters is reflected in the separate storms in dependence on geomagnetic latitude. The results were obtained by studying 5 storms of February 1967 and 1968 recorded at 6 observatories between latitude 5.7° and 53.5° with small differences in local time. These results concern the dynamic pressure of the solar wind and the function of the interplanetary electric field, which approximates the plasma injection into the ring current. This is also associated with the decay time of the storm ring. In most cases the dependence of the effect of the investigated parameters on latitude was proved and expressed in terms of quantitative relations with a reasonable degree of correlation. The derived constants were used in a model of time variations of the storm-time geomagnetic field. The storm-time variations, constructed using this model, mostly agree, as regards their main features, with the real variations, whereas differences can be observed in details, namely of a local nature.
mam maua maum, a nm uu nam naam u nu amuu auumu maum um. mam mm 5 , aumua a 1967. u 1968. m amuu um ¶rt;uana 5, 7°–53,5° nu auuu m u. mam aam ¶rt;uau ¶rt;au ma u uu nam mu n, m annuum uu na m. mu a u ana¶rt;a m ma. um a auum ma u¶rt; naam m um n¶rt;m¶rt;ua u a aa um nu ¶rt;mam mnu uu. nm u una ¶rt;u uuaum n u. ¶rt; auauu u am ¶rt;mumu, u ¶rt;ma mam m mu num a aama.相似文献
13.
L. Christoskov E. Samardjieva D. Solakov S. Simeonova C. Christova 《Studia Geophysica et Geodaetica》1990,34(1):1-9
Summary A short review of simple theoretical models for extended earthquake sources visualized as single and multiple dislocations is presented. Formulas for the duration of the radiation t
i
s
from the starting point of the destruction up to the region forming the amplitude maxima of body waves are given. A method for determining some basic parameters of extended earthquake sources (length and depth of the dislocation, azimuth of the first dislocation and the angles between every two consecutive dislocations) from the seismogram data for ti
s is presented. The procedure is applied to yield some practical results. 相似文献
14.
Vladimír Tobyáš Jaroslav Fiedler Dana Knaislová Dana Procházková Reviewer I. Pšenčík 《Studia Geophysica et Geodaetica》1985,29(1):68-74
Summary The effectiveness of recording seismic phenomena in the Kruné hory (Mts.) region in NW Bohemia by selected stations in the CSR, GDR and Poland has been estimated. Magnitude isolines of the weakest earthquakes, which can be localized and detected with an 0.9 probability, were calculated on the basis of the level of seismic disturbances at the individual stations and of the empirical dependence of the attenuation of seismic waves with distance.
a a mum umauu uu u amu ¶rt; ana¶rt; uu uau mauu a mumuu , u a a uu n a m¶rt; mau u nuu auumu amau uu m amu u auma uuuu aum¶rt; a a mu, m mm 0.9 auuam u aum.相似文献
15.
Martin Dunst 《Pure and Applied Geophysics》1977,115(3):459-471
Considering the blocking problem as a baroclinic instability problem in a dispersive wave system with diabatic heating effects, it is of great interest to investigate the role of wavegroup velocityv
gr in blocking processes, becausev
gr controls the energy transfer in the wave field. Using a Newtonian Cooling —type of forcing with a phase differencek to the main field and taking the linearized version of a two-level model, the phase speedc
r, the group velocityv
gr and the growth ratekc
i have been obtained as analytical functions of the mean zonal windU, the thermal windU
T, the coefficient of diabatic heating x, the phase differencek and the wavelengthL. Now the hypothesis is introduced, that a blocking should be expected, ifv
gr has a maximum value in the vicinity ofL
o, for whichc
r vanishes and thee-folding timet=1/kc
i (kc
i>0) is smaller than 6 days (see condition (20) in the text). One finds, that for special parameter combinations (U
T, U, ), where 15 m/secU
T25m/sec,U=10m/sec, 0.8·10–51.5·10–5 [sec–1], certain valuesL
o with an appropriate phase differencek exist, which satisfy the conditions mentioned above (for values see Table 2). TherebyL
o varies within the range 8500 km <L
o<11000 km corresponding to the preferred planetary blocking wavenumber 2 in middle latitudes 50°<<70° N. 相似文献
16.
Summary Topographic effects on tidal strains and tilts are studied using a homogeneous elastic spherical model. Expressions for local perturbing strains and tilts are derive das functions of the physical and geometrical parameters of the model. It is demonstrated that tidal tilts are affected more by the topography than tidal strains.
n ¶rt;¶rt; n u ¶rt;u u¶rt;a uu a mmu a nuu ¶rt;auu u a. ¶rt; au, nuau a uau nuu ¶rt;au u a auumu m uuu umuu naam ¶rt;u. aa, m uau nuu a uau nuu ¶rt;au.相似文献
17.
Summary Tests on the vertical vibrating table in the frequency range of70–110 Hz indicate that quartz gravity meters are10–100 times more sensitive at some frequencies than under low-frequency excitation. At high frequencies, the reading beam is at rest and deflected from the correct position. Slow fluctuations of amplitude and frequency near resonance could cause slow irregular motion of the beam with absence of low-frequency ground motion of sufficient intensity.
unmauaum a mua um¶rt; ¶rt;uana amm 70–110u mam, m a m ammaaum 10–100 a mum nu uamm au. u amm au u a¶rt;um n m mu m nu. ¶rt; auauu anum¶rt; u amm au uu aa m am uamm u ua ¶rt;a mmmm uamm au n ¶rt;mam umumu.相似文献
18.
Milan Hvoždara Klement Rosa Reviewers V. Čermák V. Petr 《Studia Geophysica et Geodaetica》1980,24(1):51-59
am amu ¶rt; ¶rt; mnu annu u u, a maua m umu mna n nnmam. a auu uu naa, m uau anu m anuu amua muna u am am u n ummamuu anu uu nmu nnmama. auum m¶rt;uauu ¶rt;mu ¶rt;mu mau anu, ammu: a) ¶rt;mu um numa amu umua mna; ) m uu uu nm aa u u u nu uuu aa nuu a nmu u; ) aau amuau anu ammuu aau, m m nm u¶rt; n u amumu um mu am. 相似文献
19.
Summary The object of the present paper is to investigate the propagation of surface waves on a non-homogeneous aeolotropic cylindrical shell surrounded by vacuum. The elastic constantsc
ij
(i, j=1,2...) and density of the material of the shell are assumed to be of the form
and
respectively, where ij, 0 are constants andk
1,k
2 are any integers. 相似文献
20.
aam, m ¶rt;-mau ¶rt;uu a ma au am m¶rt; ma m unmuu m m. ¶rt;a, u a u unmuu annuuam, m am n una u 0,1 u a u ammuuu ¶rt;mau aa m m. 相似文献