共查询到20条相似文献，搜索用时 531 毫秒
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.
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
3.
Summary The problem of the propagation of finite Love Waves in a heterogeneous elastic half space lying over a homogeneous elastic half space, using the quasilinear stress-strain relation due toS. Ferhst [4] is considered in detail. The variations of the parameter in the layer assumed to be of the form 1= 0e
z, 0e
z where is a constant andz is distance measured from the surface into the layer. 相似文献
4.
Summary Based on Peixot's theorem of topological dynamics, the unstable behaviour of hydrodynamic flows on a two-dimensional annuloid T
2
is analysed. The generating property is the curvature of the group of S
0
Diff T
2
diffeomorphisms of the (Riemannian) flow region T
2
. This group is the configuration space of the ideal fluid flowing on T
2
.
a m ma u mn u ¶rt;uauu ¶rt;am mu n¶rt;uu¶rt;¶rt;uauu nm a ¶rt; m T 2 u¶rt; mu. ¶rt;au m m a m uuann S 0 Diff T 2 ¶rt;uu amu mu ( uaa) T 2 . manna m uau nmam ¶rt; u¶rt;a u¶rt;mu a T 2 .相似文献
5.
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
6.
Fundamental-mode Rayleigh wave attenuation data for stable and tectonically active regions of North America, South America, and India are inverted to obtain several frequency-independent and frequency-dependentQ
models. Because of trade-offs between the effect of depth distribution and frequency-dependence ofQ
on surface wave attenuation there are many diverse models which will satisfy the fundamental-mode data. Higher-mode data, such as 1-Hz Lg can, however, constrain the range of possible models, at least in the upper crust. By using synthetic Lg seismograms to compute expected Lg attenuation coefficients for various models we obtained frequency-dependentQ
models for three stable and three tectonically active regions, after making assumptions concerning the nature of the variation ofQ
with frequency.In stable regions, ifQ
varies as , where is a constant, models in which =0.5, 0.5, and 0.75 satisfy fundamental-mode Rayleigh and 1-Hz Lg data for eastern North America, eastern South America, and the Indian Shield, respectively. IfQ
is assumed to be independent of frequency (=0.0) for periods of 3 s and greater, and is allowed to increase from 0.0 at 3 s to a maximum value at 1 s, then that maximum value for is about 0.7, 0.6, and 0.9, respectively, for eastern North America, eastern South America, and the Indian Shield. TheQ models obtained under each of the above-mentioned two assumptions differ substantially from one another for each region, a result which indicates the importance of obtaining high-quality higher-mode attenuation data over a broad range of periods.Tectonically active regions require a much lower degree of frequency dependence to explain both observed fundamental-mode and observed Lg data. Optimum values of for western North America and western South America are 0.0 if is constant (Q
is independent of frequency), but uncertainty in the Lg attenuation data allows to be as high as about 0.3 for western North America and 0.2 for western South America. In the Himalaya, the optimum value of is about 0.2, but it could range between 0.0 and 0.5. Frequency-independent models (=0.0) for these regions yield minimumQ
values in the upper mantle of about 40, 70, and 40 for western North America, western South America, and the Himalaya, respectively.In order to be compatible with the frequency dependence ofQ observed in body-wave studies,Q
in stable regions must be frequency-dependent to much greater depths than those which can be studied using the surface wave data available for this study, andQ
in tectonically active regions must become frequency-dependent at upper mantle or lower crustal depths.On leave from the Department of Geophysics, Yunnan University, Kunming Yunnan, People's Republic of China 相似文献
7.
A. Gouda Hussain 《Pure and Applied Geophysics》1987,125(1):67-90
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., Fa=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. 相似文献
8.
9.
Summary It has been demonstrated that the observed decrease in the second zonal geopotential harmonic linear in time and the secular decrease in the angular velocity of the Earth's rotation do not satisfy the relation defining the secular Love number k as constant during the whole history of the Earth's evolution. The discrepancy disappears if it is assumed thatdk/dt=–2.4×10–6
cy–1
.
aa, m a ¶rt;a au m aauunmuaa u u a ¶rt;a u mu au u ¶rt;mm mu, n¶rt; u a a nm mu umuu u. a uam, u ¶rt;nmumdk/dt=–2,4·10 –6 (mmu)–1 .相似文献
10.
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
11.
Summary The effect of the IMF sector boundary crossing (IMF SBC) in the vorticity area index (VAI) — the well-known dip in the VAI after IMF SBC — is found to be independent of the IMF SBC effect in the cosmic ray flux. This finding refutes a recent suggestion by Lundstedt [1] that the IMF SBC effect in VAI is caused by a decrease in cosmic ray flux, but supports the concept of the IMF SBC effects in the ionosphere and atmosphere developed by Latovika [2–4]. Cosmic rays seem to affect the troposphere in another way.
¶rt;mu nu mau nam aum n ( ) a u¶rt; na¶rt;u aumu () — um uu n — a¶rt; auu m ma nm uu . mm mam nam ¶rt;a n¶rt;u ¶rt;m¶rt;a [1], m m a nuu nma uu , n¶rt;¶rt;uam nu m u u am, aum amu [2–4]. am m uu u m um a mn ¶rt;u a.相似文献
12.
Summary Four fundamental forms of expansion of the double product of the gravity function into an infinite series are derived. Two isotropic parts are separated, one is expressed by Legendre polynomials and the other by invariants of Wigner's D-matrices.
¶rt; m n¶rt;mau ¶rt; au ¶rt; nu¶rt;uaumau uu ¶rt;. ¶rt; ¶rt; umn amu, na aam n nu a¶rt;a u ma n uauam amu ua.相似文献
13.
The effect of the velocity of the centre of a cyclone on the generation of microseisms 总被引：1，自引：0，他引：1
V. N. Tabulevich 《Pure and Applied Geophysics》1971,85(1):69-74
Summary The influence of the velocity of the movement of the centre of the cycloneV
c.c.
on the rate of amplitudes' change A/t and periods' change T/t of storm microseisms is investigated. The dependence A/t=k V
c.c.
and T/t=k
1
V
c.c.
is obtained. Unmovable depression (V
c.c.
=0) does not stipulate the change of A/t and T/t.
Presented as a scientific communication to the IASPEI Assembly in Madrid, Sept. 1969. 相似文献
u V c.c. A/t T/t . A/t=k V c.c. T/t=1 V c.c. . (V c.c. =0) A/t T/t.
Presented as a scientific communication to the IASPEI Assembly in Madrid, Sept. 1969. 相似文献
14.
Summary The morphology of the Wadati-Benioff zone in the region of Southern Kuriles and Hokkaido, based on the distribution of 4015 earthquake foci, verified the existence of an intermediate depth aseismic gap and its relation to active andesitic volcanism. A paleosubduction zone activated by an intermediate depth collision with the active subduction zone was found and described.
u Wadati-Benioff amu uu - u a¶rt;, aa a an¶rt;uu 4015 a mu, nm¶rt;ua mau n¶rt; au u amu a¶rt;um au. a a¶rt;a u nuaa a na¶rt;uu, amuuuaa nmu mu amu ¶rt;uu.相似文献
15.
Summary The dependence of Pn-wave velocities on the heat flow, temperature at the crustmantle boundary and the thickness of the Earth's crust in Europe was investigated in relation to the problem of lateral inhomogeneities in the upper mantle. A map was constructed of the distribution of Pn-wave velocities on the territory of Europe. The relations these investigations yielded, were compared with the results of laboratory experiments and all the results are discussed from the physical point of view. The conclusion drawn is that that temperature and pressure effect provide a sufficient explanation of the observed regional changes of Pn-wave velocities for the European continent.
auum ¶rt;auu mu n¶rt; ¶rt; nmu uua (Pn) u mn nm, mnam a nmu amuu u m a mumuu n a u¶rt;aa u numa ¶rt;¶rt;m amuu. mumuu n a maa a uu m Pn- a nmu uua. u¶rt;u umam ¶rt;a mama aam u¶rt;au uuu m n¶rt; amuu u u ¶rt;au u mnam mmmm mama n¶rt;aa am. ¶rt;a ¶rt;, m ua uu m Pn- a n mum ¶rt;mam um uuu mnam u ¶rt;au a nmu uua.相似文献
16.
Summary The distribution of radioactive(Th, U, K), major and selected trace(Rb, Sr, Ba, Y, Zr, V, Cr, Ni) elements of granulites from the Saxonian Granulite Complex was studied. Similarly to the South Bohemian granulites, the Saxonian granulites can be divided according to the contents of their major and trace elements into two main groups, groupA containing mostly acid and subacid granulites (K
2
O>2.5%, SiO
2
>68%), and groupB containing mostly intermediate and basic granulites (K
2
O<2.5%, SiO
2
<68%). Statistically significant differences between groupsA andB were found for all major oxides and several trace elements(Rb, V, Cr, Ni). The Saxonian granulites follow the same calc-alkaline trend as the South Bohemian, granulitesA being placed mostly in the rhyolite field and granulitesB mostly in the dacite, andesite and basalt fields of this trend. The investigated granulites are characterized by a considerable scatter ofTh andU contents accompanied by very variableTh/U ratios; theTh andU concentrations of granulitesA are substantially lower than is usual for rocks of corresponding acidity.
¶rt;a an¶rt;u a¶rt;uamu(Th, U, K) u ua ¶rt;u(Rb, Sr, Ba, Y, Zr, V, Cr, Ni) m aum n¶rt;a aaum na. naa, m u¶rt;aum n uu aam n aaum u ¶rt;u am aua, u u uu. aum n u uu ma a¶rt;um ¶rt; ¶rt;nn; nnA nua¶rt;ama a au¶rt; u au¶rt;aum (K 2 O>2,5%, Si O 2 >68%), nnB ¶rt;u u aum (K 2 O<2,5%, SiO 2 <68%). ¶rt; muunnau mm mamumuu m au ¶rt; a u u ¶rt; m ¶rt;u m(Rb, V, Cr, Ni). auaum n¶rt;¶rt;m um- m¶rt; a u -uaum;aumA a¶rt;ma a uum n, uaumB a a ¶rt;aum, a¶rt;um u aam n m m¶rt;a. ¶rt;aum — u unnA — aamum uu ¶rt;au da¶rt;uamu mTh uU.相似文献
17.
aamuam uu am a (m u naamuu n) u u (a) uu a uu mu uu. mam (19), (28) naam, m amua am mau u m ¶rt; am amu: a) na ¶rt;um am, n n a uu am u uu a uu; ) ma ¶rt;um am, m aam uu a uu. 相似文献
18.
Summary Based on the relation between the relative sunspot number R, the number of sunspot groups f
0
generated per unit time on the Sun as a whole and their average lifetime T
0
, and on the extrapolation of time behaviour of f
0
and T
0
, it is proved that abnormally high solar activity may be expected in the first half of the 21st century. At this time, the maximum annual relative sunspot numbers RM of the 11-year cycles should reach values of about 300 units. This abnormally high solar activity in the next century can be understood as the antipole of the Maunderean minimum. This forecast is used to discuss some of the possible consequences of this abnormally high solar activity for the processes on the Earth: changes of climate (heat waves and draughts in Central Europe), in the higher layers of the Earth's atmosphere (anomalous propagation of radio waves, increased effect of the density of the upper atmosphere on the orbits of man-made satellites), in seismicity (increased seismic activity in Europe and Southeast Asia), for technical devices (induced electric currents), in the biosphere. etc.
a mu ¶rt; uau a R nm, unn nm f 0 uu ¶rt;uu u a ë u u ¶rt; n¶rt;ummu uu 0 , u a manuu ¶rt;a f 0 u 0 , naa, m n nu ¶rt; 21 a u¶rt;am uum amum. aua¶rt;u ua a R m¶rt; 11-mu ua m u ¶rt;muam au 300 ¶rt;uu. m uum amum ¶rt; nuam a amun¶rt; a¶rt; uua. a m na ¶rt;am m n¶rt;mu m uum amumu a n nmau a : a uu uama (aa u a n¶rt;a ¶rt; n), a u u am u (aa anmau a¶rt;u, uu n nmmu u am a ¶rt;uu um m), a um (na ua amum n u -m uu), a muu mma (u¶rt;ua muu mu), a u u ma ¶rt;a.相似文献
19.
Summary The relation of short period PKP1 and PKP2 amplitudes from deep earthquakes in the Tonga region observed at a seismological station in Central Europe, is compared with the theoretical relations computed for different source radiation parameters and depths. The Preliminary Earth Model was used in the computations. Qualitatively good agreement of observed and calculated values was found for the radiation pattern corresponding to the likely geometry of the Tonga subduction zone. The influence of the variation of some source and model parameters on the calculated PKP1 and PKP2 relation is discussed.
¶rt;a au mu anum¶rt; mnu¶rt; PKP1 u PKP2 mu mu a, anua ¶rt; u mau ma n, mmmuu mmuuu uuau, aumau ¶rt; a naam ua umua uu aa. ama unaa ¶rt; PREM. a¶rt; u auma uu ¶rt;am am au ¶rt; a uu, mmm mmuu ¶rt;uu a a. ¶rt;am uu auau naam umu u ¶rt;u a uu am mu anum¶rt; PKP1 u PKP2.相似文献
20.
Summary The problem of inverting the geopotential series with respect to the geoid radius has been solved. A linearization of the radius powers, making use of a reference surface, has been applied. The body given by the Bruns' formula has been chosen as the reference surface. Corrections to the Bruns' formula in an analytical explicit form have been derived. An internal linearization accuracy of the order of 1 mm has been achieved. The geoid radius coefficients for the GEM-L2 model have been evaluated numerically. The corrections have been found to range from –90 to 90 cm.
m¶rt; uauauu ¶rt; aaumuu u ¶rt; ama a¶rt;ua — ma, m una uum au aumau n u u naam unu¶rt;a. u u¶rt; una um uum u nmuaa u uum au a¶rt;ua — ma. ¶rt;a¶rt;amua ua, aa uauau, n¶rt;a 1 . u¶rt; u am ¶rt; ¶rt;uaumau n GEM-L2. au na nm mm m am nu annuauuu¶rt;a, a a m a, n¶rt;a ± 90 .相似文献