In situ stress measurement is not well accepted yet in Indonesia due to the unavailability of technology, high costs and because
it is impractical in remote regions. Alternatively, the Kaiser effect of acoustic emission (AE) can be used as a method for
determining the stress-state at depth, without creating induced stress and is practical in remote areas. This paper is focused
on the development of the AE test. The research has started to study the phenomenon of stress memory in a rock sample, the
factors influencing the phenomenon, and finally, to determine the in situ stresses around underground excavations by applying
the AE method. It is expected that knowledge in gaining the most important input parameters for maintaining the stability
of underground excavations can be well understood and be reliably conducted at a reasonable cost. 相似文献
We present the stellar and gas kinematics of a sample of 18 nearby late-type spiral galaxies (Hubble types ranging from Sb to Sd), observed with the integral-field spectrograph SAURON at the 4.2-m William Herschel Telescope. SAURON covers the spectral range 4800–5380 Å, allowing us to measure the Hβ, Fe, Mg b absorption features and the emission in the Hβ line and the [O iii ]λλ4959, 5007 Å and [N i ]λλ5198, 5200 Å doublets over a 33 × 41-arcsec2 field of view. The maps cover the nuclear region of these late-type galaxies and in all cases include the entire bulge. In many cases the stellar kinematics suggests the presence of a cold inner region, as visible from a central drop in the stellar velocity dispersion. The ionized gas is almost ubiquitous and behaves in a complicated fashion: the gas velocity fields often display more features than the stellar ones, including wiggles in the zero-velocity lines, irregular distributions, ring-like structures. The line ratio [O iii ]/Hβ often takes on low values over most of the field, probably indicating a wide-spread star formation. 相似文献
Soil liquefaction on 28 September 2018 in Palu, Indonesia, included one of the largest soil movements ever, where objects on the ground surface moved hundreds of meters away and settlements sank into the mud. Some preliminary studies show that in addition to a strong earthquake, there are strong indications that a confined aquifer in the Palu valley worsened the liquefaction. The role of the confined aquifer can be recognized early on from one of various signs, namely the presence of massive surface inundations suspected due to groundwater expulsion which is thought to originate mostly from the confined aquifer. This paper describes the mechanism of the soil liquefaction in Palu from the perspective of earthquake hydrogeology, focusing on the groundwater expelled from an unconfined aquifer and especially from the underlying confined aquifer through hydraulic inter-connection between the two, which is possible due to simultaneous interaction of excess pore pressure dissipation and enhanced permeability driven by an earthquake in the near field. If this hypothesis proves to be strong, there are implications for engineering practices because the evaluation of potential soil liquefaction carried out currently in the geotechnical engineering field generally only involves the role of shallow groundwater and/or the unconfined aquifer and the role of soil layers not deeper than 30 m from the ground surface. It may be necessary to complement current evaluation practice with an evaluation of the deep groundwater response to earthquakes, especially if the deep groundwater is artesian and productive, with a relatively thin confining layer.
The purpose of this paper is to study the nature of variation of O3 concentration of Antarctic Survey Stations and its correlation with solar ultraviolet radiation. Solar UV data for the period November 1978 to October 1984 are taken from Solar Geophysical Data Book. In absence of solar UV data for long period, a calibration curve between solar UV radiation and solar flare number (S.F.NO.) is drawn. (A straight line is obtained and correlation coefficient between two variables is 80%). The equation of straight line from least square principle becomes, UV flux = 0.2672 + 2.7578 × 10?5 × S.F.NO. From this equation UV flux values for long period are calculated from known values of solar flare numbers. O3 concentration of two Antarctic Survey Stations, Halley Bay (76? S, 27? W) and McMurdo (78? S, 166? E) are considered for analysis and following important results are obtained:
Yearly variations of O3 concentrations and UV radiations are mainly controlled by their October concentrations.
Correlation coefficient between O3 concentration and UV radiation is 62% for the month of October. For the other months it is poor.
It is concluded that dramatic decrease of O3 concentration at Antarctica is independent of solar UV radiation and chemical processes are responsible for special depletion of O3.
The paper presents the effect of solar flare index on Antarctic O3 depletion. Solar flare index is the actual representative of energy output of any flare event. A calibration curve between
solar flare index and relative sunspot number is drawn. (A straight line is obtained and correlation coefficient between two
variables is 0.95, n = 27, P < 0.01).The equation of straight line from least square principle becomes,
Solar Flare Index (If) = 1.0932 * Relative Sunspot Number- 9.4391.
From this equation solar flare index for long period is calculated from known values of relative sunspot numbers. O3 concentration of two antarctic Survey Stations, Halley Bay (76 °S, 27 °W) and McMurdo (78 °S, 166 °E) are considered for
analysis and following results are obtained:
(i) Correlation coefficient between O3 concentration and solar flare index during Antarctic Spring is not so significant.
(ii) It is concluded that dramatic decrease of O3concentration during Antarctic Spring is independent of solar parameters.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
