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排序方式: 共有325条查询结果,搜索用时 15 毫秒
221.
Bent Hasholt Marek Madeyski 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):38-45
Geografisk Tidsskrift, Danish Journal of Geography 98: 38–45. Water samples have been collected since 1969, at the Lavborg Bridge gauging station, on the river Ansager Å in South-West Jutland. Different regression equations of concentration versus discharge have been tested. The regression equations are used together with daily discharges to compute the daily suspended loads. Comparisons between measured and computedloads for different periods when water samples were taken twice a day suggest that the 25 computed annual load values have an uncertainty of less than ± 10%. The variation in annual loads shown is therefore significant and probably caused by increased rainfall in the eigthies. The average total suspended sediment yield for the 25 year period was 7 t/km2/year, of which the organic load contributed 3.2 t/km2/year. 相似文献
222.
Jiří Borovička Juraj Tóth Antal Igaz Pavel Spurný Pavel Kalenda Jakub Haloda Ján Svoreň Leonard Kornoš Elizabeth Silber Peter Brown Marek Husárik 《Meteoritics & planetary science》2013,48(10):1757-1779
The Ko?ice meteorite fall occurred in eastern Slovakia on February 28, 2010, 22:25 UT. The very bright bolide was imaged by three security video cameras from Hungary. Detailed bolide light curves were obtained through clouds by radiometers on seven cameras of the European Fireball Network. Records of sonic waves were found on six seismic and four infrasonic stations. An atmospheric dust cloud was observed the next morning before sunrise. After careful calibration, the video records were used to compute the bolide trajectory and velocity. The meteoroid, of estimated mass of 3500 kg, entered the atmosphere with a velocity of 15 km s?1 on a trajectory with a slope of 60° to the horizontal. The largest fragment ceased to be visible at a height of 17 km, where it was decelerated to 4.5 km s?1. A maximum brightness of absolute stellar magnitude about ?18 was reached at a height of 36 km. We developed a detailed model of meteoroid atmospheric fragmentation to fit the observed light curve and deceleration. We found that Ko?ice was a weak meteoroid, which started to fragment under the dynamic pressure of only 0.1 MPa and fragmented heavily under 1 MPa. In total, 78 meteorites were recovered in the predicted fall area during official searches. Other meteorites were found by private collectors. Known meteorite masses ranged from 0.56 g to 2.37 kg. The meteorites were classified as ordinary chondrites of type H5 and shock stage S3. The heliocentric orbit had a relatively large semimajor axis of 2.7 AU and aphelion distance of 4.5 ± 0.5 AU. Backward numerical integration of the preimpact orbit indicates possible large variations of the orbital elements in the past due to resonances with Jupiter. 相似文献
223.
Marek Wolf Petr Harmanec Josip Kleczek Pavel Mayer 《Astrophysics and Space Science》1987,134(1):205-208
Geographical, seasonal, and day-to-day variations in the vertical distributions of atmospheric density and temperature must be considered in the design and operation of reentry vehicles. This work is part of a continuing effort to compile, analyze, and present information on the distribution of the atmospheric temperature in a form suitable for use in the design and operation of aerospace vehicles. We have used temperature data obtained from rockets which are mostly based on the datasonde system throughout the decade 1969–1978. Profiles and the individual arrays of coefficients of correlation of the temperature at 20 km with temperature at higher altitudes up to 60 km are shown for each season for locations in the low, middle, and high latitudes. 相似文献
224.
Kosmulski M Maczka E Marczewska-Boczkowska K Rosenholm JB 《Marine pollution bulletin》2003,46(1):120-122
Electroacoustic method was used to measure the zeta potentials of mineral oxides and calcium carbonate in artificial sea water (pH 8), and the following values were obtained: synthetic hematite: 0.87 mV; goethite: 1.01 mV; fumed silica: -3.56 mV; quartz: -1.38 mV; calcium carbonate: 1.91 mV. The absolute values of the zeta potentials obtained in the present study are substantially lower than the zeta potentials in seawater reported by other authors. Our results indicate that the effect of electrostatic repulsion in the interactions between the particles of these materials in seawater is negligible. 相似文献
225.
Marek Zbik 《Meteoritics & planetary science》1994,29(2):222-223
Abstract— The Yarle Lakes 001 meteorite was a single stone of 913 g found approximately 20 km north of Watson, South Australia, in 1990 October. It consists of olivine (Fa18.7 ± 0.4, n = 30), low-Ca pyroxene (Fs16.6 ± 0.2 Wo 12 + 0.4, n = 15). feldspar, high-Ca pyroxene, metallic Fe-Ni and troilite. Based on texture and mineral chemistry, Yarle Lakes 001 is classified as a H5 chondrite of shock stage S3. 相似文献
226.
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228.
Zhan Zhang Paul Fenter Jeffery G. Catalano James D. Kubicki David J. Wesolowski Neil C. Sturchio 《Geochimica et cosmochimica acta》2006,70(16):4039-4056
Adsorption of Zn2+ at the rutile TiO2 (110)-aqueous interface was studied with Bragg-reflection X-ray standing waves (XSW), polarization-dependent surface extended X-ray absorption fine structure (EXAFS) spectroscopy, and density functional theory (DFT) calculations to understand the interrelated issues of adsorption site, its occupancy, ion-oxygen coordination and hydrolysis. At pH 8, Zn2+ was found to adsorb as an inner-sphere complex at two different sites, i.e., monodentate above the bridging O site and bidentate between two neighboring terminal O sites. EXAFS results directly revealed a four or fivefold first shell coordination environment for adsorbed Zn2+ instead of the sixfold coordination found for aqueous species at this pH. DFT calculations confirmed the energetic stability of a lower coordination environment for the adsorbed species and revealed that the change to this coordination environment is correlated with the hydrolysis of adsorbed Zn2+. In addition, the derived adsorption locations and the occupancy factors of both sites from three methods agree well, with some quantitative discrepancies in the minor site location among the XSW, EXAFS, and DFT methods. Additional XSW measurements showed that the adsorption sites of Zn2+ were unchanged at pH 6. However, the Zn2+ partitioning between the two sites changed substantially, with an almost equal distribution between the two types of sites at pH 6 compared to predominantly monodentate occupation at pH 8. 相似文献
229.
Ongoing tectonic reactivation of the Outer Carpathians and its impact on the foreland: Results of borehole breakout measurements in Poland 总被引:1,自引:0,他引:1
The direction of present-day maximum horizontal compression (= SHmax = tectonic stress) was interpreted for 62 wells in Poland, using the method of borehole breakout analysis of 4-arm and 6-arm dipmeter logs. The study area covers complex tectonic junction of the Carpathian orogen and its foreland, which comprises the East European Craton (EEC) divided by the Teisseyre–Tornquist zone (TTZ) from the Palaeozoic platform of western Poland. For this area, frequent deviation of the SHmax direction from NW–SE characteristic for the Atlantic ridge push has been interpreted in terms of the ALCAPA tectonic push. In the Upper Silesian segment of the Polish Outer Carpathians (POC), NNE–SSW-oriented SHmax in the accretionary wedge differs significantly from NNW–SSE SHmax in the autochthonous basement. The above discrepancy points to uncoupled type of the suture in this segment of the POC. In this scenario the ALCAPA push involves the nappes and is compensated in the top of the basement, which is expressed by systematic SHmax rotations. In the accretionary wedge of the eastern Małopolska segment, SHmax follows the trend perpendicular to the strike of nappes. It is in general agreement with NNE–SSW-oriented SHmax in the autochthonous basement that also parallels the ALCAPA push direction. Similarity in stress orientation between these structural levels implies coupled suture zone in this segment of the POC. Further to the north, ALCAPA push is transmitted into the foreland plate where it causes N–S orientation of SHmax, as determined for sedimentary cover of the EEC. Within the Baltic portion of the EEC, further SHmax rotation towards the intermediate NNW–SSE position suggests balance between the ALCAPA push and the ridge push components. Within the TTZ, common SHmax rotations from N–S to NW–SE indicate structurally controlled accommodation of the ALCAPA push. In the Palaeozoic platform of western Poland, Mesozoic complex of the Fore-Sudetic Monocline reveals NNE–SSW-directed SHmax that differs from NW–SE-oriented SHmax in the Variscan accretionary wedge. Here, mechanical decoupling along Zechstein evaporates is likely.
Presented set of breakout data from Poland shows that recent compressive reactivation of the Carpathians exerts strong impact on the stress field of the foreland plate at a distance of 700 km from the suture. Due to this effect, the Fore-Carpathian stress domain within the North European stress province can be discriminated. 相似文献
230.