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81.
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Miroslav Košina 《International Journal of Coal Geology》1984,4(3):263-280
Proposals for new scientific classifications of bituminous coals are based on micropetrographic parameters, i.e. vitrinite reflectance as a criterion of the coalification and maceral composition, presupposed to express the connection between the genetic peculiarities and physical, chemical, and technological properties of the coal mass. In the case of coals with high inertinite contents, however, the utilizability of these parameters meets with difficulties resulting from the subjectivity of determining the different transitional material and from insufficient knowledge of inertinite behaviour at higher temperatures. In the case of the maceral-variable bituminous coals produced in the Ostrava-Karviná Coal Basin, these insufficiencies are not important since it is especially the expression of the variability of the properties of isometamorphic vitrinites, which has decisive effects up-on the course of the thermo-chemical transformations, that is of principal importance to the scientific classification of these coals.In the first approximation, the properties of isometamorphic vitrinites may be expressed by the parameter (H/O)at, closely connected with fluidity. While the micropetrographic parameters reflect in particular the peculiarities in the chemical structure of the aromatic parts of coal macromolecules, the parameter (H/O)at expresses the properties of the non-aromatic structures of vitrinite, significantly affecting the course of its thermal degradation. The experimental results show that the value of the parameter (H/O)at, fluidity and the course of degassing the coal of a lower coalification are independent of the maceral composition and vitrinite reflectance; also that the caking and coking properties of low-rank coals are especially dependent on the parameter (H/O)at and partially on the micropetrographic parameters. All these facts should be taken into consideration in preparing new scientific classifications of bituminous coals. 相似文献
83.
Marta Krsová Miroslav Krs Petr Pruner Richard Chvojka Reviewer V. Kropáček 《Studia Geophysica et Geodaetica》1989,33(4):338-361
Summary Porcellanites and palaeo-slags from North Bohemia are natural materials which can be used to derive the palaeomagnetic directions and palaeointensity of the geomagnetic field active at the time of caustic alteration. The origin of these rocks, called erdbrands, was due to the caustic alteration of predominantly pelitic sediments as a result of underground fires conditioned by spontaneous ignition of coal seams. The caustic alteration occurred during the Upper Pliocene to the Quaternary. Three procedure based on the methods by Thellier and Nagata are presented in the paper. The newly developed apparatus MAVACS (Magnetic Vacuum Control System) was used for the thermal demagnetization of samples. A procedure based on multi-component analysis was also proposed and tested. Besides some methodic results, it was found that the geomagnetic field intensity varied during the respective period within the limits of 48%±4% to 154%±32% of the present geomagnetic field intensity.
aum u na au a mumuu uu n¶rt;mam nu¶rt; amua, m n¶rt;¶rt;um ¶rt; ¶rt;u naaum anau u naumumuaum n, ¶rt;m amu uu. mu n¶rt;, aa ¶rt;a¶rt;, uu n¶rt; uu amu uu num num a¶rt; n¶rt; ¶rt;mu aau . amu uu u m nu¶rt; m nua ¶rt; mmu nu¶rt;a. am n¶rt; mu umnmau nua, n¶rt;¶rt;u ¶rt; ¶rt;u naumumu, nuau a m¶rt; u aama. a aamaa annaama MAVACS (Magnetic Vacuum Control System) a unaa ¶rt; mu aauuau ¶rt; amu aa. n¶rt; u n n¶rt;¶rt;, a a munm aau amuauu. nu m¶rt;uu au, ma ma, m umumaum n u¶rt; nu¶rt; a n¶rt;a 48%±4%-154%±32% au umumu aum n.相似文献
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Comparative study of methods for WHPA delineation 总被引:3,自引:0,他引:3
Paradis D Martel R Karanta G Lefebvre R Michaud Y Therrien R Nastev M 《Ground water》2007,45(2):158-167
Human activities, whether agricultural, industrial, commercial, or domestic, can contribute to ground water quality deterioration. In order to protect the ground water exploited by a production well, it is essential to develop a good knowledge of the flow system and to adequately delineate the area surrounding the well within which potential contamination sources should be managed. Many methods have been developed to delineate such a wellhead protection area (WHPA). The integration of more information on the geologic and hydrogeologic characteristics of the study area increases the precision of any given WHPA delineation method. From a practical point of view, the WHPA delineation methods allowing the simplest and least expensive integration of the available information should be favored. This paper presents a comparative study in which nine different WHPA delineation methods were applied to a well and a spring in an unconfined granular aquifer and to a well in a confined highly fractured rock aquifer. These methods range from simple approaches to complex computer models. Hydrogeological mapping and numerical modeling with MODFLOW-MODPATH were used as reference methods to respectively compare the delineation of the zone of contribution and the zone of travel obtained from the various WHPA methods. Although applied to simple ground water flow systems, these methods provided a relatively wide range of results. To allow a realistic delineation of the WHPA in aquifers of variable geometry, a WHPA delineation method should ensure a water balance and include observed or calculated regional flow characteristics. 相似文献
87.
Bohumír Janský Zbyněk Engel Miroslav Šobr Vojtěch Beneš Karel Špaček Serguei Yerokhin 《Natural Hazards》2009,50(1):83-96
An interdisciplinary study of glacier-related hazards in the Petrov lake region (Ak-Shiirak Range, the Inner Tien-Shan, Kyrgyzstan)
has been undertaken to identify potential dangers to the area. A cooperative effort from experts in the fields of hydrology,
glaciology, geomorphology and geophysics has been employed in this study. For the hazard assessment, evolution of the Petrov
glacier and lake was reconstructed using historical reports, aerial photographs and satellite images. Geomorphological mapping
and geophysical soundings was applied to the lake territory and the moraine dam. This has identified potentially hazardous
areas of the dam including subsurface drainage zones and cracks that could cause a sudden extremely high discharge. In the
past three decades, the Petrov lake has doubled in size, while in recent years, its area has been increasing by more than
92,000 square metres per year. Although there is no evidence for an imminent outburst, the dramatic increase in the lake’s
size emphasizes the importance of this study. 相似文献
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