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201.
Tensile Strength of Rock Under Elevated Temperatures 总被引:4,自引:0,他引:4
Rock strength affects the behaviour of rocks differently under different conditions such as temperature, time, pressure, presence
of fluids, rock mass characteristics and stress history of rock in a natural environment. It is not always easy to replicate
such conditions of undisturbed rock in a laboratory scale. Hence, it is imperative to study the rock behaviour with respect
to every such condition which the rock experiences since its time of formation. Temperature is one of the key parameters which
influence the rock throughout its history, ranging from the conditions of formation, experience of depth (loading/unloading)
or deformational and metamorphic history. Also, increase in rock temperature; say due to the thermal stress changes like disposal
of spent nuclear fuels affects the strength of the surrounding rock. In this work, the effects of temperature on the tensile
strength of rock have been studied. The results obtained were interesting as the strength of rock is found to increase considerably
up to a particular temperature after which it starts falling by as much as 70% around 250°C. 相似文献
202.
The various observed harmonics of the cosmic ray variation may be understood on a unified basis if the free space cosmic ray anisotropy is non-sinusoidal in form. The major objective of this paper is to study the first three harmonics of high amplitude wave trains of cosmic ray intensity over the period 1991–1994 for Deep River Neutron Monitoring Station. The main characteristic of these events is that the high amplitude wave trains shows a maximum intensity of diurnal component in a direction earlier than 1800 Hr/co-rotational direction. It is noticed that these events are not caused either by the high-speed solar wind streams or by the sources on the Sun responsible for producing these streams such as polar coronal holes. The direction of semi-diurnal anisotropy shows negative correlation with Bz. The occurrence of high amplitude events is dominant for the positive polarity of Bz component of IMF. The diurnal amplitude of these events shows a negative and the time of maximum shows a weak correlation with disturbance storm time index Dst. The direction of tri-diurnal anisotropy of these events is found to significantly correlate with geomagnetic activity index Ap. 相似文献
203.
The unusually low amplitude anisotropic wave train events (LAEs) in cosmic ray intensity using the ground based Deep River
neutron monitor data has been studied during the period 1991–94. It has been observed that the phase of the diurnal anisotropy
for the majority of the LAE events remains in the co-rotational direction. However, for some of the LAE events the phase of
the diurnal anisotropy shifts towards earlier hours as compared to the annual average values. On the other hand, the amplitude
of the semi-diurnal anisotropy remains statistically the same, whereas phase shift-towards later hours; a similar trend has
also been found in case of tri-diurnal anisotropy. The high-speed solar wind streams do not play a significant role in causing
the LAE events. The occurrence of LAE is independent of the nature of the Bz component of IMF polarity.
Published in Astrofizika, Vol. 50, No. 2, pp. 313–324 (May 2007). 相似文献
204.
205.
We have attempted to devise a scheme by which it may be possible to identify pulsars which are likely to be γ-ray pulsars.
We apply this test to a representative population of pulsars and identify the likely candidates for γ emission. We also discuss
some individual cases including the Crab and Vela pulsars. 相似文献
206.
Stability of non-self gravitating, non-accreting fluid disk rotating around a Schwarzschild black hole is studied by using
a variational principle. We find a set of solutions which depending on the value of a parameter, either a stable or an unstable
specific angular momentum distribution (Rayleigh's criterion). Using these solutions we find that the calculations based on
the variational principle yield results which agree with the Rayleigh criteria when a suitable choice of the trial function
is made. 相似文献
207.
There are indications now that globular clusters contain a large number of low magnetic field millisecond pulsars. Since millisecond
pulsars are expected to emit γ-rays due to curvature radiation, it is likely that globular clusters will themselves be sources
of γ-rays bright enough to be detectable by present day instruments. Using the expression derived by Scharlemann, Arons &
Fawley (1978) of the energy acquired by the electrons moving along the open magnetic field lines of the pulsars we have calculated
the likely luminosity of γ-rays from globular clusters. We discuss our results in the light of the calculations reported in
the literature based on some of the other models. 相似文献
208.
Trophic State Index (TSI) of Nainital lake has been determined using secchi disk transparency as well as using Landsat 7 ETM
bands. The insitu water quality parameters like pH and dissolved oxygen (DO) have been measured using multiparameter water
quality instrument TROLL 9500. Various interpolation techniques have been tested and the best one has been applied to prepare
the water quality images of Nainital lake. The analysis of Landsat images have shown that the lake water is in eutrophic condition
from the year 2000 to 2010. However, the trophic state index values are found to be relatively less during the year 2006 to
2008. This may be due to the lake restoration programmes undertaken by the Lake Development Authorities. 相似文献
209.
This paper describes the effects of time step on the simulation of tropical climate in the NCAR-Community Atmosphere Model version 3 (CAM3). A set of multi-year integrations are carried out in a real-planet framework using actual land?Cocean distribution and observed sea surface temperature. Over the tropics there is an increase in total rainfall with a decrease in time step size. Using a lower time step, there is a decrease in the convective component of rainfall, however, the stratiform component increases, and more than compensates the decrease in the former, thus leading to a higher total rainfall. A decrease in time step leads to an increase in the frequencies of moderate, and heavy rainfall categories, which is responsible for the increase in time mean total rainfall over the tropics. Also, the spatial distribution of rainfall becomes more realistic during both summer and winter seasons. In regard to the simulation of equatorial waves, it is found that a lower time step leads to a reduction in the speed of Kelvin waves. The latent heating profile becomes more bottom-heavy with a reduction in time step size, which potentially leads to slower Kelvin waves. Finally, additional experiments conducted in an aqua-planet framework show a consistent and systematic change in the analyzed variables with change in time step, and hence confirm the robustness of the results across modeling frameworks. 相似文献
210.
Detrital type of manganese ore bodies in the Precambrian Iron Ore Group of rocks occur in the Bonai-Keonjhar belt, Orissa
besides stratiform (bedded type) and stratabound-replacement types of deposits. These ores appear in form of large boulders
within lateritised aprons at various depths, often reaching beyond 30 m from the surface. Overprinting of primary structures,
presence of mixed Fe-clasts and Mnooliths/pisoliths, mineral species of different generations and wide chemical variation
amongst morphological varieties and from boulder to boulder are the characteristic hallmarks of such ore bodies. Features
associated with ores occurring in different morphologies, namely: spongy, platy, recemented, and massive varieties from a
typical profile of Orahari Mn-ore body in Keonjhar district are described. Recemented variety may be further classified into
sub-varieties such as canga, agglomerate, and mangcrete. Common primary Fe-minerals are hematite, martite with relict magnetite.
The secondary Fe-Mn phases are goethite, specularite, cryptomelane, lithiophorite, chalcophanite, manganite, and pyrolusite.These
are ore bodies of allochthonous nature developed through a number of stages during terrain evolution and lateritisation. Secondary
processes such as reworking of pre-existing crust through remobilisation, solution, precipitation, cementation, transport,
etc. are responsible for the development of such detrital ore bodies in the Bonai-Keonjhar belt of Eastern India. 相似文献