排序方式： 共有75条查询结果，搜索用时 31 毫秒
1.
Łukasz Wiejaczka Małgorzata Kijowska-Strugała Paweł Pierwoła Mariusz Nowak 《Water Resources》2018,45(6):861-872
The article presents the spatial and temporal dynamics of water temperature in two reservoirs on the upper course of the Dunajec River in the Polish Carpathians. It aims at presenting how spatial patterns and time evolution of water temperature in the reservoirs affect the water temperature in the river. The analysis is based on the results of water temperature measurements in hydrometric verticals in two reservoirs as well as in the river upstream and downstream of the reservoirs. The measurements were carried out in 2012 and 2013, in hydrometeorological conditions typical for each season of the year. Based on the measurements, it has been demonstrated that the complex of reservoirs affects the water temperature in the river over the year and the existence of the smaller lower reservoir may attenuate the cooling or heating effect of the main reservoir on the river. 相似文献
2.
3.
4.
The location of the seismic event hypocenter is the very first task undertaken when studying any seismological problem. The
accuracy of the solution can significantly influence consecutive stages of analysis, so there is a continuous demand for new,
more efficient and accurate location algorithms. It is important to recognize that there is no single universal location algorithm
which will perform equally well in any situation. The type of seismicity, the geometry of the recording seismic network, the
size of the controlled area, tectonic complexity, are the most important factors influencing the performance of location algorithms.
In this paper we propose a new location algorithm called the extended double difference (EDD) which combines the insensitivity
of the double-difference (DD) algorithm to the velocity structure with the special demands imposed by mining: continuous change
of network geometry and a very local recording capability of the network for dominating small induced events. The proposed
method provides significantly better estimation of hypocenter depths and origin times compared to the classical and double-difference
approaches, the price being greater sensitivity to the velocity structure than the DD approach. The efficiency of both algorithms
for the epicentral coordinates is similar. 相似文献
5.
Application of surface-wave tomography to mineral exploration: a case study from Siilinjärvi,Finland
Federico Da Col Myrto Papadopoulou Emilia Koivisto Łukasz Sito Mikko Savolainen Laura Valentina Socco 《Geophysical Prospecting》2020,68(1):254-269
In order to assess the feasibility and validity of surface-wave tomography as a tool for mineral exploration, we present an active seismic three-dimensional case study from the Siilinjärvi mine in Eastern Finland. The aim of the survey is to identify the formation carrying the mineralization in an area south of the main pit, which will be mined in the future. Before acquiring the data, we performed an accurate survey design to maximize data coverage and minimize the time for deployment and recollection of the equipment. We extract path-averaged Rayleigh-wave phase-velocity dispersion curves by means of a two-station method. We invert them using a computationally efficient tomographic code which does not require the computation of phase-velocity maps and inverts directly for one-dimensional S-wave velocity models. The retrieved velocities are in good agreement with the data from a borehole in the vicinity, and the pseudo three–dimensional S-wave velocity volume allows us to identify the geological contact between the formation hosting most of the mineralization and the surrounding rock. We conclude that the proposed method is a valid tool, given the small amount of equipment used and the acceptable amount of time required to process the data. 相似文献
6.
Natural Hazards - On 17 April 2015, the Wujek/?l?sk underground coal mine in Poland was struck by a strong induced tremor of magnitude M4.0. The event was followed by a massive rock burst... 相似文献
7.
Tomasz Brachaniec Krzysztof Szopa Łukasz Karwowski 《Meteoritics & planetary science》2014,49(8):1315-1322
We report the first occurrence of moldavites in Poland. This discovery confirms the hypothesis that moldavites could have been distributed up to 500 km from the Ries crater in Germany. The tektites were reworked from Middle Miocene sediments and redeposited in Late Miocene (Pannonian) fluvial deposits of the Gozdnicka Formation in Lower Silesia. The Polish moldavites are represented by nine (<8 mm) fragments with a total of 0.471 g. The lack of the autochthonous tektites indicates that tektites investigated here had to be redeposited in a fluvial environment, probably from the Lusatian area. The chemical composition of the Polish moldavites plots in the same area with those from other localities. 相似文献
8.
Tomasz Brachaniec Krzysztof Szopa Łukasz Karwowski 《Meteoritics & planetary science》2015,50(10):1697-1702
Moldavites represent tektites derived from the Ries impact structure (~24 km diameter, ~15 Myr old) in southern Germany. Two new localities with parautochthonous moldavites in southwestern Poland were found. In these localities, fluvial sediments of the so‐called Gozdnicka formation host the moldavites. Characteristic tektite features, especially bubbles and inclusions of lechatelierite, are reported. The moldavites' size distribution and their abraded shapes indicate that they were redeposited from the nearby Lusatia substrewn field. 相似文献
9.
Abstract The vertical profiles of streamwise velocities are computed on flood plains vegetated with trees. The calculations were made based on a newly developed one-dimensional model, taking into account the relevant forces acting on the volumetric element surrounding the considered vegetation elements. A modified mixing length concept was used in the model. An important by-product of the model is the method for evaluating the friction velocities, and consequently bed shear stresses, in a vegetated channel. The model results were compared with the relevant experimental results obtained in a laboratory flume in which flood plains were covered by simulated vegetation. 相似文献
10.
Mariusz Lamentowicz Willem Van Der Knaap Łukasz Lamentowicz Jacqueline F. N. Van Leeuwen Edward A. D. Mitchell Tomasz Goslar Christian Kamenik 《第四纪科学杂志》2010,25(2):190-202
We present the first testate amoeba‐based palaeohydrological reconstruction from the Swiss Alps, and the first depth to the water table (DWT) calibration dataset for this region. Compared to existing models, our new calibration dataset performs well (RMSEP = 4.88), despite the length of the water table gradient covered (53 cm). The present‐day topography and vegetation of the study mire Mauntschas suggest that it is partly ombrotrophic (large Sphagnum fuscum hummocks, one of which was the coring site) but mostly under the minerotrophic influence of springs in the mire and runoff from the surrounding area. Ombrotrophic Sphagnum fuscum hummocks developed at the sampling site only during the last 50 years, when testate amoebae indicate a shift towards dry and/or acid conditions. Prior to AD 1950 the water table was much higher, suggesting that the influence of the mineral‐rich water prevented the development of ombrotrophic hummocks. The reconstructed DWT correlated with Pinus cembra pollen accumulation rates, suggesting that testate amoebae living on the mire and P. cembra growing outside of it partly respond to the same factor(s). Finally, temperature trends from the nearby meteorological station paralleled trends in reconstructed DWT. However, contrary to other studies made on raised bogs of northwestern Europe, the highest correlation was observed for winter temperature, despite the fact that testate amoebae would more logically respond to moisture conditions during the growing season. The observed correlation with winter temperature might reflect a control of winter severity on surface moisture during at least the first part of the growing season, through snow melt and soil frost phenomena influencing run‐off. More ecohydrological work on sub‐alpine mires is needed to understand the relationships between climate, testate amoebae and peatland development. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献