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121.
The temple of Apollo in Delphi (Greece), built in 550 B.C., has been used to reconfirm a novel method of dating carved megalithic stone buildings using thermoluminescence (TL) (Liritzis, 1994). A calcitic (marble) sample was taken from the western side of the well-known inscribed polygonal wall, which constitutes the southern external support foundations of the temple. A partially bleached TL methodology was devised to determine first the ancient residual TL and then the correct archaeological dose. The obtained TL age of 420 ± 300 B.C. is compatible, within the margin of error, with the archaeological age. © 1997 John Wiley & Sons, Inc. 相似文献
122.
The work presented in this paper lies under the scope of a research program aiming to assess the impact of deep coal mining induced vibrations on the surface constructions. The concerned section of the program is dedicated to the study of geological site effects and their influence on the mining induced vibrations for which the experimental investigations have been carried out and developed in this paper (Part 1). The empirical methods based on H/V spectral ratios have been applied on data sets provided from mining induced vibrations recorded within private residences above the deep coalmine as well as complementary measurements of ambient noise. The results evidence an amplified zone in the southern part of the Gardanne basin where drilling data confirmed the presence of particularly fractured and soft stratigraphic units. This joint analysis of induced seismicity and ambient noise enabled to validate the method based on H/V ratios applied to the mining context. 相似文献
123.
124.
Widdows J Donkin P Staff FJ Matthiessen P Law RJ Allen YT Thain JE Allchin CR Jones BR 《Marine environmental research》2002,53(4):327-356
The objective of this research was to quantify the impact of pollution along the coastlines of the Irish Sea. Pollution assessment was based on the combined measurement of scope for growth (SFG), and chemical contaminants in the tissues of mussels (Mytilus edulis) collected from 38 coastal sites around the Irish Sea during June-July in 1996 and 1997. On the UK mainland coast, the SFG showed a general trend with a significant decline in water quality in the Liverpool and Morecambe Bay region. High water quality was recorded along the west coast of Wales, as well as southwest England and northwest Scotland (clean reference sites outside the Irish Sea). Along the coast of Ireland there was a similar trend with reduced SFG within the Irish Sea region. SFG was generally low north of Duncannon and then improved north of Belfast. The poor water quality on both sides of the Irish Sea is consistent with the prevailing hydrodynamics and the spatial distribution of contaminants associated with urban/ industrial development. The decline in SFG of mussels on both sides of the Irish Sea was associated with a general increase in contaminant levels in the mussels. Certain contaminants, including PAHs, TBT, sigmaDDT, Dieldrin, gamma-HCH, PCBs, and a few of the metals (Cd, Se, Ag, Pb), showed elevated concentrations. Many of these contaminants were particularly elevated in the coastal margins of Liverpool Bay, Morecambe Bay and Dublin Bay. A quantitative toxicological interpretation (QTI) of the combined tissue residue chemistry and SFG measurements indicated that at the majority of coastal sites, c. 50 to > 80% of the observed decline in SFG was due to PAHs as a result of fossil fuel combustion and oil spills. TBT levels were highest at major ports and harbours, but these concentrations only made a minor contribution to the overall reduction in SFG. At no sites were individual metals accumulated to concentrations that could cause a significant effect on SFG. The study identified many sites where the observed reduction in SFG was far greater than predicted from the limited number of chemical contaminants analysed, thus indicating the presence of additional 'unknown toxicants'. Sewage (containing domestic, agricultural and industrial components) appears to be an important contributor to reduced SFG and linear alkylbenzenes (LABs) and As may provide suitable 'sewage markers'. There was a highly significant positive correlation between SFG and As (P < 0.001). This relationship may be due to reduced As uptake by algal food material and mussels at sites with elevated P04 concentrations (e.g. at sites with sewage inputs). Phosphate is a known competitive inhibitor of As accumulation, at least in algae. The results highlight that further research is required on 'sewage markers' in mussels. The SFG approach therefore provides a rapid, cost-effective and quantitative measure of pollution impact, as well as a means of identifying the causes through a QTI of tissue contaminants levels. It also serves to identify the presence of unidentified toxicants and areas that require further study. 相似文献
125.
Siavash Amirrahmat Khalid A. Alshibli Maha F. Jarrar Boning Zhang Richard A. Regueiro 《国际地质力学数值与分析法杂志》2018,42(8):999-1015
Constitutive modeling of granular materials has been a subject of extensive research for many years. While the calculation of the Cauchy stress tensor using the discrete element method has been well established in the literature, the formulation and interpretation of the strain tensor are not as well documented. According to Bagi, 1 researchers mostly adopt well‐known continuum or discrete microstructural approaches to calculate strains within granular materials. However, neither of the 2 approaches can fully capture the behavior of granular materials. They are considered complementary to each other where each has its own strengths and limitations in solving granular‐mechanics problems. Zhang and Regueiro 2 proposed an equivalent continuum approach to calculating finite strain measures at the local level in granular materials subjected to large deformations. They used three‐dimensional discrete element method results to compare the proposed strains measures. This paper presents an experimental application of the Zhang and Regueiro 2 approach using three‐dimensional synchrotron microcomputed tomography images of a sheared Ottawa sand specimen. Invariant Eulerian finite strain measures were calculated for representative element volumes within the specimen. The spatial maps of Eulerian octahedral shear and volumetric strain were used to identify zones of intense shearing within the specimen and compared well with maps of incremental particle translation and rotation for the same specimen. The local Eulerian volumetric strain was compared to the global volumetric strains, which also can be considered as an averaging of all local Eulerian volumetric strains. 相似文献
126.
The radius, mass, total number of baryons, and other parameters of static, spherically symmetric, superdense stars are calculated. A model with one Ricci-flat inner space of arbitrary dimensionality and the approximation p1=?0.5ε + ap for additional components of the energy — momentum tensor are used (ε and ρ are the total energy density and the pressure of the stellar matter and a is a fitting parameter). In the case of white dwarfs, the results of the multidimensional theory do not depend on the dimensionality D of space-time for ?10 ? a ? 10 and coincide with the analogous data of the general theory of relativity (GTR). For neutron stars there is a dependence on D and a. For D>4, in particular, the greatest mass Mmax of a neutron star as a function of a has a maximum at 3<a(D) ? 4, which exceeds the greatest mass M max 0 =2.14 M⊙ in the GTR. A comparison of theoretical results with observational data determines the allowable values of a. Data for PSR 1913 + 16 lead to 0.2 ≤ a ≤ 9.2 in the case of D=26, while the results of [P. C. Joss and S. A. Rappaport, Annu. Rev. Astron. Astrophys.,22, 537 (1984)] lead to the stricter limits 1 ≤ a ≤ 7.4. 相似文献
127.
Intensive mining and processing of Ag, Sn, Pb and Zn ores have occurred in various locations within and around the city of
Potosí, Bolivia since 1545. Surface and subsurface waters, stream sediments and soils are contaminated with various ecotoxic
metals in the headwaters of the economically vital, yet highly impacted, upper Rio Pilcomayo watershed. Previous studies have
documented downstream trace metal contamination, however, not addressed specific sources. The AMD discharges identified in
this study help link downstream pollution to primary origins. The majority of AMD would be considered high-strength due to
metal concentrations and acidity orders of magnitude greater than typical AMD. Discharges from both operating and abandoned
portals as well as tailings-related deposits displayed a high degree of heterogeneity with total metal concentrations ranging
from 0.11 to 7480, <0.022 to 889, <0.0006 to 65.3, <0.001 to 310, 0.12 to 72,100, 0.3 to 402, <0.012 to 34.8, and 0.24 to
19,600 mg/L of Al, As, Cd, Cu, Fe, Mn, Pb and Zn, respectively. Net acidity and pH ranged from −10 to 246,000 mg/L as CaCO3 equivalent and 0.90–6.94 standard units, respectively. Data were gathered during two sampling events centered around the
most extreme periods of the dry and wet seasons of one water-year. Loadings to local streams were marginally greater for most
metals in the wet season. If observed loadings are historically representative, Cerro Rico AMD has contributed thousands of
tonnes of ecotoxic metals to the upper Rio Pilcomayo over the last five centuries. Metal and hydrogen ion concentrations in
the majority of AMD sampled were several orders of magnitude above discharge limits set by the Bolivian government, yet no
action has historically or contemporarily been taken. 相似文献
128.
129.
Boška J. Šauli P. Altadill D. German Solé J. Alberca L.F. 《Studia Geophysica et Geodaetica》2003,47(3):579-586
We investigate the short-term fluctuations in the period range from 15 to 180 minutes in the electron density variations of the F region ionosphere. Electron density profiles obtained at the ionospheric stations of Pruhonice (49.9° N, 14.5° E) and Ebro (40.8° N, 0.5° E) at five minute time sampling have been used for this analysis. The diurnal changes of the activity of the acoustic gravity wave fluctuations (AGW) show a clear enhancement during and several hours after sunrise. The periods of such AGW's are about 60 to 75 minutes and these waves propagates vertically through the ionosphere from a source located at an altitude of 180-220 km. The most likely source for these events seems to be passage of the Solar terminator. 相似文献
130.
The authors elaborate upon the “multiplicity principle” in remote sensing, i.e., the need for repeated imaging at a variety of scales, spatial resolutions, spectral bands, and times of imaging in order to attain the maximum information possible. They then explore the ways it can be applied in agricultural research, through two different image comparison and interpretation strategies. A detailed example is presented of the use of a multitemporal imaging strategy for the recognition of several agricultural crops from false color composite imagery. Translated by Edward Torrey, Alexandria, VA 22308 from: G. V. Dobrovol'skiy and V. L. Andronikov, eds., Aerokosmicheskiye metody v pochvo-vedenii i ikh ispol'zovaniye v sel'skom khozyaystve: sbornik nauchnykh trudov [Remote Sensing Methods in Soil Science and Their Utilization in Agriculture: A Collection of Scientific Works]. Moscow: Nauka, 1990, pp. 47-55. 相似文献