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111.
The development of gypsum maze caves under artesian conditions has been simulated. The numerical model simulations show that the evolution of maze caves in this type of setting requires structural preferences such as laterally extended fissure networks in a horizon of the gypsum layer. Without any structural preferences vertical shafts rather than maze caves are predicted to develop. The most important stage for the development of horizontal caves under artesian conditions is found to be the initial karstification period. During this period the structure of the mature conduit system is established. The solutional enlargement of conduits is spatially extended, total dissolution rates are higher than the later ones. 相似文献
112.
大气有机污染分析和评价:Ⅲ.美国迈阿密市大气有机污染监测与分析 总被引:1,自引:1,他引:1
自1994年6月至1995年3月对(美)迈阿密市大气颗粒物及干、湿沉降物中的多种有机化合物进行了定量分析与监测,并依据分析结果结合分子参数对有机污染水平的季节性变化、气候条件影响和清除机理等进行了探讨。 相似文献
113.
Most of the mesotrophic to eutrophic lakes in central Europe have been showing signs of oligotrophication during recent years. The question as to how the fish populations would react to this new situation was investigated looking at the growth rate of roachRutilus rutilus (L.) of Lake Sarnen, central Switzerland. The water temperature sum as day-degrees over 12 to 13°C for the months of June to October was found to be the predominant factor governing the marked year-to-year fluctuations of the growth rate. Contrary to expectation, the decreasing trophic state of the lake has not yet manifested itself noticeably in the growth rate. 相似文献
114.
Summary This paper presents an improved investigation technique for in-situ determination of the deformation properties of rock masses, which are important parameters in the desing of foundations. This technique permits testing on a circular, one square metre area of the rock. In order to obtain reproducible loading conditions when testing, an equipment was introduced that gave almost uniformly distributed loading of the rock surface. This device is described in this paper. Displacement measurements are made in a central measuring hole, since a point of zero displacement, located equidistant between the loaded surface and the upward-pointing anchoring forces, offered a suitable reference point. In this way, the measuring device is also well protected against disturbing variations in temperature. During cyclic loading and unloading, charateristic load/deflection graphs are recorded, which directly demonstrate the deformation properties of the rock, such as the modulus of deformation at different loads, linearity deviation from linearity, as well as hysteresis effects and creep. It is clear that the results of the investigation apply only to the measuring point—the place at which the investigation was carried out. The properties of the rock nearby may vary considerably. The procedure for using this method of investigation for testing improvement measures for turbine foundations is shown in some examples. 相似文献
115.
Rudolf A. Treumann 《Astrophysics and Space Science》1993,201(1):135-147
Information in the universe evolves according to a nonlinear law, which results from a combination of nonlinear dynamics and quantum theory. The Kolmogoroff-Sinai entropy rate of the Universe evolves in inverse proportion to the temperature. Since the evolution of temperature is known from standard cosmology, the time dependence of the universal entropy rate can be determined and the temporal evolution of the universal information content can be calculated. Information starts growing at the enormous rate of 1044 bits per second from an initial value of at least 2 (seven) bits at Planck time. However, it reaches its contemporary value only if one or more inflationary phases have been passed by the Universe in the course of its evolution. 相似文献
116.
Thorsten Christian Rudolf J. Schneider Harald A. Frber Dirk Skutlarek Michael T. Meyer Heiner E. Goldbach 《洁净——土壤、空气、水》2003,31(1):36-44
In the last years more and more often detections of antimicrobially active compounds (“antibiotics”) in surface waters have been reported. As a possible input pathway in most cases municipal sewage has been discussed. But as an input from the realm of agriculture is conceivable as well, in this study it should be investigated if an input can occur via the pathway application of liquid manure on fields with the subsequent mechanisms surface run‐off/interflow, leaching, and drift. For this purpose a series of surface waters, soils, and liquid manures from North Rhine‐Westphalia (Northwestern Germany) were sampled and analyzed for up to 29 compounds by HPLC‐MS/MS. In each of the surface waters antibiotics could be detected. The highest concentrations were found in samples from spring (300 ng/L of erythromycin). Some of the substances detected (e.g., tylosin), as well as characteristics in the landscape suggest an input from agriculture in some particular cases. In the investigation of different liquid manure samples by a fast immunoassay method sulfadimidine could be detected in the range of 1…2 mg/kg. Soil that had been fertilized with this liquid manure showed a content of sulfadimidine extractable by accelerated solvent extraction (ASE) of 15 μg/kg dry weight even 7 months after the application. This indicates the high stability of some antibiotics in manure and soil. 相似文献
117.
118.
Vogler Daniel Walsh Stuart D. C. von Rohr Philipp Rudolf Saar Martin O. 《Acta Geotechnica》2020,15(8):2327-2340
Acta Geotechnica - Thermal spallation drilling is a contact-less means of borehole excavation that works by exposing a rock surface to a high-temperature jet flame. In this study, we investigate... 相似文献
119.
Due to increasing population growth and anthropogenic pollution in the coastal zone, contamination of water and seafood with pathogens is probably responsible for the greatest number of human morbidities and mortalities worldwide. Hence, regular monitoring of waterborne pathogens is required to safeguard public health. Current techniques rely on the culturing of nonpathogenic indicator organisms (e.g. Escherichia coli or coliforms) for detection by inference. However, recent epidemiological evidence shows poor correlation between concentrations of E. coli/coliform and waterborne pathogens. Moreover, traditional methods are slow, not cost-effective, unable to distinguish harmful from benign strains, and fail to detect viable but nonculturable pathogens. The use of the polymerase chain reaction (PCR) has provided rapid and highly sensitive methods for the specific detection of pathogenic microorganisms. This paper briefly reviews some DNA-based technologies for waterborne pathogen detection, and describes our recent development of two new DNA-based technologies—quantitative multiplex PCR (Q-mPCR) and DNA microarray—that allow simultaneous and cost-effective detection and quantification of numerous pathogens in a single sample, which is superior to the culture methods currently in use. 相似文献
120.
Hartmut W. Hoeness Rudolf Mueller Erich W. Rodeck Friedrich B. Siebers 《Astrophysics and Space Science》1989,160(1-2):193-197
For about 20 years SCHOTT has been supplying the glass ceramic ZERODUR, a material with very low thermal expansion. Besides many other applications, ZERODUR is excellently suited for the manufacture of mirror substrates for telescopes. About 80% of all telescopes in the western world with mirror diameters >1.8 m have been equipped with ZERODUR during the last 10 years. The development of modern astronomical telescopes is aimed at larger primary mirrors and lighter secondary mirrors.New techniques have been developed by SCHOTT for manufacture of thin monolithic mirror blanks of more than 8 m in diameter. The development of thin meniscus shaped shells using the spin-casting technique was successfully completed last year. During a test production several mirror substrates up to 4.1 m in diameter and down to 57 mm in thickness could be produced. The know-how has been acquired for the fabrication of mirror substrates of more than 8 m in diameter by the spin-casting technique.SCHOTT has also performed considerable developmental work in the field of lightweighted ZERODUR mirror substrates which can be generated using different techniques: forming of the lightweighted structure during casting, fusion of individual components to a total structure and lightweighting of a massive block by various mechanical machining methods.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.Registered trademark of SCHOTT Glaswerke, Mainz. 相似文献