排序方式: 共有12条查询结果,搜索用时 15 毫秒
1.
The ore body “T” is the newly discovered massive-pyrite type one which is located in the central part of the Bor copper mine. The main copper minerals are chalcocite-digenite, covellite and enargite. Small amounts of colusite are frequently present in the ore-body. It mostly occurs as the distinct exsolutions in digenite and, associating with enargite and covellite. Composition of the studied colusite shows enriched Sn content, giving an empirical formula from Cu24.7V1.8Fe0.2As5.1Sb0.2Sn0.8S32 to Cu26.7V2.0Fe0.3As3.0Sb0.3Sn3.5S32. This colusite represents a solid solution between colusite and nekrasovite within a range of 14–54 mol % nekrasovite. Most of the analyses show content of <50 mol % nekrasovite corresponding to the Sn-bearing colusite variety, while one analysis shows content of 54 mol % nekrasovite corresponding to the As-bearing nekrasovite. 相似文献
2.
Veljko?Perovi? Ljubomir??ivoti?Email author Ratko?Kadovi? Aleksandar??or?evi? Darko?Jaramaz Vesna?Mrvi? Mladen?Todorovi? 《Environmental Earth Sciences》2013,70(1):115-129
This study employed genetic adaptive neural networks in the classification of high-resolution satellite images from which data related to surface conditions in mountainous areas of Taiwan were derived. Principal component analysis was then used to extract factors associated with the threat of natural disaster, and logistic regression was used to compute the probability of disaster occurrence. Through field surveys, interviews with district officials and a review of relevant literature, the probability of a sediment disaster was estimated as well as the vulnerability of the villages concerned and the degree to which these villages were prepared, to construct a risk evaluation model. A geographic information system was used to plot regional risk maps as a means to enhance the safety of residents in the study area. The risk assessment model can be used by authorities to make provisions for high-risk areas, to reduce the number of casualties and social costs of sediment disasters. 相似文献
3.
The central and highest area of Mt. Prokletije (Albanian Alps) is situated in northern Albania and eastern Montenegro (at 42°30′N). The highest peak is Maja e Jezerces (2694 m). Detailed geomorphological mapping was used to reconstruct the positions of former glaciers. The longest Ropojana glacier had a length of 12.5 km and surface of 20 km2; others include Valbona Glacier (9.5 km, 10.5 km2), Grbaja Glacier (5 km, 6.7 km2) and Bogićevica Glacier (6 km, 6.9 km2). Three series of moraines can be distinguished: the lowest at an average altitude of 990 m (average ELA 1750 m), the middle series at 1350 m (ELA 1942 m), and the highest at 1900 m (ELA 2123 m). As no advanced dating methods have yet been used to provide a numerical chronological framework for these features, hypotheses are made based on the comparison with the advanced studies of other similar mountains in the Mediterranean region. The moraines of the first stage (lowest series) correspond to one of pre-LGM glaciations (Middle or even Early Würmian), the second stage moraines probably correspond to LGM, and the third stage could be attributed to Younger Dryas. The mapping included a number of inactive and active rock glaciers, as well as three small active glaciers (surface 5 ha and less), at 1980–2100 m altitude, in the area close to Maja e Jezerces. 相似文献
4.
5.
Borna Lužar-Oberiter Tamás Mikes Hilmar von Eynatten Ljubomir Babić 《International Journal of Earth Sciences》2009,98(5):1097-1108
Cr-spinel is a common heavy mineral in the sandstones of Cretaceous synorogenic sedimentary formations of the NW Dinarides,
Croatia. The rocks occur in isolated exposures in the uplifted basement units of Medvednica, Ivanščica, Žumberak and Samobor
Mountains near Zagreb. In this area, evidence of the early Alpine evolution of the Dinarides is obscured due to strong dismemberment
of pre-Tertiary tectonostratigraphic units resulting from an intense tectonic history, as well as due to the widespread sedimentary
cover of the Pannonian Basin. Electron microprobe analyses of detrital Cr-spinels from the Oštrc Formation reveal that in
the Early Cretaceous the ophiolitic source area was predominantly composed of harzburgite peridotites and associated cumulate
rocks, which developed in a supra-subduction zone setting. The supply of Cr-spinels with the same chemical signature remained
dominant until the end of the Cretaceous, suggesting that exposed remnants of the same ophiolite belt persisted through the
Cretaceous and/or that recycling was significant. Similarities with data reported from the Northern Calcareous Alps and the
Transdanubian Central Range imply that a rather extensive harzburgitic ophiolite belt probably extended along the Adriatic
margin during the Early Cretaceous. A slight trend of increasing variation in the Cr# is observed from the Early to the latest
Cretaceous, suggesting that the source areas became more heterogeneous with the ongoing Cretaceous tectonic evolution. Differences
in Cr-spinel compositions in two contemporaneous latest Cretaceous formations are well in line with existing data on heavy
mineral proportions, which together identify contrasting hinterland geology for these formations and strongly suggest the
coeval existence of two separate basins.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
Sk Ajim Ali Farhana Parvin Jana Vojteková Romulus Costache Nguyen Thi Thuy Linh Quoc Bao Pham Matej Vojtek Ljubomir Gigović Ateeque Ahmad Mohammad Ali Ghorbani 《地学前缘(英文版)》2021,12(2):857-876
Hazards and disasters have always negative impacts on the way of life.Landslide is an overwhelming natural as well as man-made disaster that causes loss of natural resources and human properties throughout theworld.The present study aimed to assess and compare the prediction efficiency of different models in landslide susceptibility in the Kysuca river basin,Slovakia.In this regard,the fuzzy decision-making trial and evaluation laboratory combining with the analytic network process(FDEMATEL-ANP),Na?ve Bayes(NB)classifier,and random forest(RF)classifier were considered.Initially,a landslide inventory map was produced with 2000 landslide and nonlandslide points by randomly dividedwith a ratio of 70%:30%for training and testing,respectively.The geospatial database for assessing the landslide susceptibility was generated with the help of 16 landslide conditioning factors by allowing for topographical,hydrological,lithological,and land cover factors.The ReliefF methodwas considered for determining the significance of selected conditioning factors and inclusion in the model building.Consequently,the landslide susceptibility maps(LSMs)were generated using the FDEMATEL-ANP,Na?ve Bayes(NB)classifier,and random forest(RF)classifier models.Finally,the area under curve(AUC)and different arithmetic evaluation were used for validating and comparing the results and models.The results revealed that random forest(RF)classifier is a promising and optimum model for landslide susceptibility in the study area with a very high value of area under curve(AUC=0.954),lower value of mean absolute error(MAE=0.1238)and root mean square error(RMSE=0.2555),and higher value of Kappa index(K=0.8435)and overall accuracy(OAC=92.2%). 相似文献
7.
Speleothems occurring in some caves of the carbonate Dinarides line all channel surfaces, and have been deposited from meteoric waters under phreatic conditions. Such phreatic speleothemic deposition modifies common experience (l) that meteoric phreatic conditions cause dissolutional widening of cave voids, and (2) that speleothems imply vadose conditions. The phreatic speleothems described here postdate an early polygenetic evolution of the cave voids, and predate the last, vadose stage. They were likely produced during the late/postglacial warming period, when dissolved carbonate was amply supplied, and when there was much water available for saturation of underground voids. Phreatic speleothems may be used as a tool for time correlation of internal deposits, both within one cave and within a karst region. They indicate an important stage in the history of the ground-water regime of an area. In general, phreatic speleothems help in better understanding of the development of subterranean voids and related karst/palaeokarst. 相似文献
8.
Milivoj Kuzmić Mirko Orlić Muhamed Karabeg Ljubomir Jeftić 《Estuarine, Coastal and Shelf Science》1985,21(4):481-499
The present paper describes a three-dimensional hydrodynamical numerical model of the Northern Adriatic. The model is based on the approach of N.S. Heaps in which the integral transformations are used to reproduce the vertical distribution of velocity. The model is applied to reproduce the wind-induced motion in the Northern Adriatic during winter. Hydrographic, sea level and current data collected during the MEDALPEX are used to verify the model predictions. Analysis of the empirical data suggests that the bura wind induces the most pronounced, although transient, contribution to the Northern Adriatic current field. The model predictions clearly show the controlling influence of a shallower bottom along the Italian coast. The model to data comparison suggests for the eddy viscosity coefficient value an order of magnitude lower than expected from literature data. The quadratic law for bottom friction and wind-stress curl have been identified as possible improvements of the model. 相似文献
9.
10.
Ljubomir Tashkov Katarina Manova Lidija Krstevska Mihail Garevski 《Bulletin of Earthquake Engineering》2010,8(4):995-1018
The ALSC base isolation system was investigated by testing a church model to the scale 1/3.5 on the two-component shaking
table at the IZIIS’ Laboratory, Skopje, Macedonia. The investigation was performed within the frames of the European FP6 project
PROHITECH, related to seismic protection of historical buildings by innovative and reversible mixed technology systems. This
system was originally developed in 2001 and applied on a model of a steel reservoir. The church model was tested twice: with
an active base-isolation system and fixed to the base. The effectiveness of the base-isolation system was investigated by
the transfer function/floor response spectra technique. Special software for calculation of the transfer functions and floor
response spectra based on experimental data, referred as “SPECTRA”, was developed by the authors of this paper. The main objective
of the investigations presented in this paper was evaluation of the effectiveness of the ALSC floating sliding base-isolation
system by using the Response Spectra approach. Comparison of the Floor Response Spectra was done for two cases a fixed base
model and a base-isolated model. The base response spectrum was calculated from the input time history of the Montenegro earthquake
compressed 3.5 times (geometry scale of the model). The Transfer Functions and the Floor response Spectra at a particular
level were calculated from the Cross Power Spectra (CPS) and the Auto-Power Spectra. The obtained results showed that the
effect of the base-isolation system was considerable, with a low transmissibility of energy from shake table to the model. 相似文献