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21.
Bianchi type-II, VIII, and IX models have been investigated in scalar-tensor theories developed by Saez (1985), Saez and Ballester (1985), and Lau and Prokhovnik (1986) (under the assumption of a certain relationship between the cosmological term and the scalar field ). The dynamical behaviour of these models has been studied. 相似文献
22.
Artificial neural network and liquefaction susceptibility assessment: a case study using the 2001 Bhuj earthquake data,Gujarat, India 总被引:2,自引:0,他引:2
D. Ramakrishnan T. N. Singh N. Purwar K. S. Barde Akshay. Gulati S. Gupta 《Computational Geosciences》2008,12(4):491-501
This study pertains to prediction of liquefaction susceptibility of unconsolidated sediments using artificial neural network
(ANN) as a prediction model. The backpropagation neural network was trained, tested, and validated with 23 datasets comprising
parameters such as cyclic resistance ratio (CRR), cyclic stress ratio (CSR), liquefaction severity index (LSI), and liquefaction
sensitivity index (LSeI). The network was also trained to predict the CRR values from LSI, LSeI, and CSR values. The predicted
results were comparable with the field data on CRR and liquefaction severity. Thus, this study indicates the potentiality
of the ANN technique in mapping the liquefaction susceptibility of the area. 相似文献
23.
M. Gamo P. Goyal Manju Kumari U. C. Mohanty M. P. Singh 《Boundary-Layer Meteorology》1994,67(3):213-227
Annual variations of mixed-layer characteristics at New Delhi, India have been studied for a weak monsoon (1987) and a strong monsoon (1988) year. In the weak monsoon year (1987), the maximum mixing depthh
max was found to have a value of around 3000 m during the pre-monsoon, less than 2000 m during the summer monsoon, around 2000 m during the post-monsoon, and less than 1000 m in the winter season. For the strong monsoon year (1988),h
max values were less than 1987 values for comparable periods throughout the year. The seasonal and yearly differences ofh
max were explained by the surface energy balance and potential temperature gradient at a time close to sunrise. According to the spatial patterns of obtained by an objective analysis of the 850 to 700 hPa layers. mixed-layer characteristics obtained at New Delhi are representative of the north and central regions of India. 相似文献
24.
Discrete chorus-type emission and whistler precursors recorded in March 1972 during day time hours at our ground based station Gulmarg are presented. It is shown that discrete chorus type emissions are generated in the equatorial region (L 1.2) during cyclotron resonance interaction between the propagating whistler wave and the gyrating electrons. The whistler precursors are explained in terms of the mechanism suggested by Dowden (1972). 相似文献
25.
The discussion in the preceding paper is restricted to the uncertainties in magnetic-field-iine tracing in the magnetosphere resulting from published standard errors in the spherical harmonic coefficients that define the axisymmetric part of the internal geomagnetic field (i.e. gn0 ± gn0). Numerical estimates of these uncertainties based on an analytic equation for axisymmetric field lines are in excellent agreement with independent computational estimates based on stepwise numerical integration along magnetic field lines. This comparison confirms the accuracy of the computer program used in the present paper to estimate the uncertainties in magnetic-field-line tracing that arise from published standard errors in the full set of spherical harmonic coefficients, which define the complete (non-axisymmetric) internal geomagnetic field (i.e. gnm ± gnm and hnm ± hnm). An algorithm is formulated that greatly reduces the computing time required to estimate these uncertainties in magnetic-field-line tracing. The validity of this algorithm is checked numerically for both the axisymmetric part of the internal geomagnetic field in the general case (1 n 10) and the complete internal geomagnetic field in a restrictive case (0 m n, 1 n 3). On this basis it is assumed that the algorithm can be used with confidence in those cases for which the computing time would otherwise be prohibitively long. For the complete internal geomagnetic field, the maximum characteristic uncertainty in the geocentric distance of a field line that crosses the geomagnetic equator at a nominal dipolar distance of 2 RE is typically 100 km. The corresponding characteristic uncertainty for a field line that crosses the geomagnetic equator at a nominal dipolar distance of 6 RE is typically 500 km. Histograms and scatter plots showing the characteristic uncertainties associated with magnetic-field-line tracing in the magnetosphere are presented for a range of illustrative examples. Finally, estimates are given for the maximum uncertainties in the locations of the conjugate points of selected geophysical observatories. Numerical estimates of the uncertainties in magnetic-field-line tracing in the magnetosphere, including the associated uncertainties in thelocations of the conjugate points of geophysical observatories, should be regarded as first approximations in the sense that these estimates are only as accurate as the published standard errors in the full set of spherical harmomic coefficients. As in the preceding paper, howerver, all computational techniques developed in this paper can be used to derive more realistic estimates of the uncertainties in magnetic-field-line tracing in the magnetosphere, following further progress in the determination of more accurate standard errors in the spherical harmonic coefficients.Also Visiting Reader in Physics, University of Sussex, Palmer, Brighton, BN1 9QH, UK 相似文献
26.
An exact analysis of Hall current on hydromagnetic free convection with mass transfer in a conducting liquid past an infinite vertical porous plate in a rotating fluid has been presented. Exact solution for the velocity field has been obtained and the effects ofm (Hall parameter),E (Ekman number), andS
c (Schmidt number) on the velocity field have been discussed.Nomenclature
C
species concentration
-
C
w
concentration at the porous plate
-
C
species concentration at infinity
-
C
p
specific heat at constant pressure
-
D
chemical molecular diffusivity
-
g
acceleration due to gravity
-
E
Ekman number
-
G
Grashof number
-
H
0
applied magnetic field
-
j
x, jy, jz
components of the current densityJ
-
k
thermal conductivity
-
M
Hartman number
-
m
Hall parameter
-
P
Prandtl number
-
Q
heat flux per unit area
-
S
c
Sehmidt number
-
T
temperature of the fluid near the plate
-
T
w
temperature of the plate
-
T
temperature of the fluid in the free-stream
-
u, v, w
components of the velocity fieldq,
-
U
uniform free stream velocity
-
w
0
suction velocity
-
x, y, z
Cartesian coordinates
-
Z
dimensionless coordinate normal to the plate.
Greek symbols
coefficient of volume expansion
- *
coefficient of expansion with concentration
- e
cyclotron frequency
-
dimensionless temperature
- *
dimensionless concentration
-
v
kinematic viscosity
-
density of the fluid in the boundary layer
-
coefficient of viscosity
- e
magnetic permeability
-
angular velocity
-
electrical conductivity of the fluid
- e
electron collision time
- u
skin-friction in the direction ofu
- v
skin-friction in the direction ofv 相似文献
27.
In order to carry out a numerical study of the structure of rotationally distorted polytropes, the Monaghan and Roxburgh (1965) method is extended to include the second-order term in the perturbation parameter, . 相似文献
28.
A study of natural convection in hydrodynamic flows of a viscous heat generating fluid in the presence of Hall currents and variable suction has been carried out. The governing equations for the magnetohydrodynamic fluid flow and heat transfer are solved. The effects of Hall currentm and heat source parameter on the velocity and temperature distributions are discussed. 相似文献
29.
A model of solar flare is proposed, taking into account the high temperature (109K) produced by the shock wave generated by the hydromagnetic wave at the junction of sunspot and the area just outside it and subsequent explosive hydrogen burning, producing the desired 1028–29 ergs of a solar flare. 相似文献
30.
Vibrational transition probabilities, namely Franck—Condon factors and
-centroids have been evaluated by an approximate analytical method for the (A–X), (A–X), and (A–X) system of YO molecule. Morse potential energy curves forX
2+,A
22,A22, andA22, states of YO have been constructed using the latest spectroscopic data. The value of
-centroids for the band have been found to decrease linearly with the corresponding wavelengths. We show results for two new transitions of (A–X) and (A–X) and five new bands of (A–X) of YO in the umbral spectrum of the Sun. 相似文献