A generalization of distribution data for characterizing the performance of float-sink coal cleaning devices     

Byron S. Gottfried 《International Journal of Mineral Processing》1978,5(1):1-20

The performance of float-sink coal cleaning devices customarily is characterized by a distribution curve, in which the percent of feed reporting to clean coal is plotted against specific gravity. For a given vessel and a given feed a family of distribution curves can be obtained, each having its own specific gravity of separation.This paper presents a method for combining these distribution curves at different specific gravities of separation, for a given coal cleaning vessel and a given feed, into a single, generalized distribution curve which is independent of the specific gravity of separation. This curve can be expressed in tabular form or it can be represented mathematically by an exponential type equation, known as a Weibull function.A different generalized distribution curve will be obtained for each of several different size fractions. A method is presented for utilizing these curves with feeds which encompass a broad spectrum of sizes.The well-known concepts of error area and probable error are extended to the generalized distribution curve. It is shown that the conventional probable error, and — under certain conditions — the conventional error area, are directly proportional to the specific gravity of separation for a given vessel and a given feed size.  相似文献   

Surface-active substances on rainwater and atmospheric particles     

Winfried Seidl  Gottfried Hänel 《Pure and Applied Geophysics》1983,121(5-6):1077-1093

The surface tension lowering by surface-active substances has been measured on rainwater, melted snow, and dispersions of atmospheric particles in water, with a film balance and a tensiometer. The precipitation water was sampled during 1979, 1980, and 1981 in the city of Frankfurt/Main. From measurements with the film balance technique, normalized concentrations of insoluble and weakly soluble surface-active substances have been estimated. Soluble surface-active substances were determined from measurements with a tensiometer. It was found that the normalized concentration of theinsoluble and weakly soluble surface-active material on rainwater or melted snow shows a maximum during late spring of about 2.5 · 10⁻⁷ moles/l and a minimum during wintertime of about 5 · 10⁻⁸ moles/l. These concentrations are too low to influence significantly the condensation of water vapour on cloud droplets or the evaporation of water from them. Thesoluble surface-active material on rainwater or melted snow was found to have concentrations of the order of 2 · 10⁻⁶ moles/l. These concentrations are also too small to have a significant influence on cloud physical processes.  相似文献   

Seismic hazard assessment for low-seismicity areas — Case study: Northern Germany     

Gottfried Grünthal  Christian Bosse 《Natural Hazards》1996,14(2-3):127-139

The problem of assessing seismic hazard in low-seismicity areas becomes obvious in many practical applications. A typical low-seismicity area, which experienced damaging earthquakes in historical times, is the North German Plain, for which a case study is presented. It is shown how seismic hazard assessments are influenced by different interpretations of historical key earthquakes, changes in b-value as well as variations of the upper bound magnitude assumed for the seismic source regions. The latter strongly influences the hazard results in the case of very low b-values for long return periods.  相似文献   

Site-specific response spectra from the combination of microzonation with probabilistic seismic hazard assessment—An example for the Cologne (Germany) area     

Stefano Parolai  Gottfried Grünthal  Rutger Wahlstrm 《Soil Dynamics and Earthquake Engineering》2007,27(1):49-59

Seismic noise was measured at some 20 sites in the Cologne area (Germany) aligned nearly perpendicular to a graben structure. The H/V spectral noise ratio for each site was used to derive realistic S-wave velocity profiles down to the bedrock by means of a genetic algorithm inversion. Numerical simulations were performed for different combinations of source and propagation path parameters: focal depth, epicentral distance, attenuation and fault mechanism. Synthetic seismograms were produced and converted to Fourier and response spectra. Finally, the site-specific values from response spectral ratios, with their uncertainties, were used to modify attenuation functions entering the logic-tree algorithm of the probabilistic seismic hazard assessment (PSHA). The site-specific response spectra show the significance of taking into account the local S-wave velocity structure in PSHA.  相似文献   

Statistical representation of generalized distribution data for float-sink coal-cleaning devices: Sand cones     

Byron S. Gottfried 《International Journal of Mineral Processing》1981,8(1):89-91

An earlier paper by this writer presented a method for combining distribution data for float-sink coal-cleaning devices into a single, generalized distribution curve which is independent of the specific gravity of separation. A nonlinear exponential-type equation was used to represent each of the curves and to determine the corresponding generalized probable error. Performance data for five common coal-cleaning devices were analyzed using this method.In this paper the method is applied to another common coal-cleaning device — the sand cone. Numerical values are presented for the constants in the exponential-type generalized distribution equation and for the corresponding generalized probable error. Several different feed size-fractions are considered.  相似文献   

Multifrequency studies of the enigmatic gamma-ray source 3EG J1835+5918     

O. Reimer †  K.T.S. Brazier  A. Carramiñana  G. Kanbach  P.L. Nolan  D.J. Thompson 《Monthly notices of the Royal Astronomical Society》2001,324(3):772-780

The EGRET telescope aboard the NASA Compton Gamma-Ray Observatory ( CGRO ) has repeatedly detected 3EG J1835+5918, a bright and steady source of high-energy gamma-ray emission which has not yet been identified. The absence of any likely counterpart for a bright gamma-ray source located 25° off the Galactic plane initiated several attempts of deep observations at other wavelengths. We report on counterparts in X-rays on a basis of a 60-ks ROSAT HRI image. In order to conclude on the plausibility of the X-ray counterparts, we reanalysed data from EGRET at energies above 100 MeV and above 1 GeV, including data up to CGRO observation cycle 7. The gamma-ray source location represents the latest and probably the final positional assessment based on EGRET data. We especially address the question of flux and spectral variability, here discussed using the largest and most homogeneous data set available at high-energy gamma-rays for many years. The results from X-ray and gamma-ray observations were used in a follow-up optical identification campaign at the 2.2-m Guillermo Haro Telescope at Cananea, Mexico. VRI imaging has been performed at the positions of all of the X-ray counterpart candidates, and spectra were taken where applicable. The results of the multifrequency identification campaign toward this enigmatic unidentified gamma-ray source are given, especially on the one object which might be associated with the gamma-ray source 3EG J1835+5918. This object has the characteristics of an isolated neutron star and possibly of a radio-quiet pulsar.  相似文献   

The SHARE European Earthquake Catalogue (SHEEC) for the time period 1900–2006 and its comparison to the European-Mediterranean Earthquake Catalogue (EMEC)     

Gottfried Grünthal  Rutger Wahlström  Dietrich Stromeyer 《Journal of Seismology》2013,17(4):1339-1344

This short communication describes the differences of the seismicity data file of the SHARE European Earthquake Catalogue from 1900 to 2006 in comparison to the European-Mediterranean Earthquake Catalogue by Grünthal and Wahlström (J Seismol 16:535–570, 2012). SHARE is the EC project Seismic Hazard Harmonization in Europe. Differences occur in the very north of the study area, in Greece and adjacent areas, and with respect to local volcanic earthquakes at Etna, Italy.  相似文献   

Water surface mapping from airborne laser scanning using signal intensity and elevation data     

Bernhard Höfle  Michael Vetter  Norbert Pfeifer  Gottfried Mandlburger  Johann Stötter 《地球表面变化过程与地形》2009,34(12):1635-1649

In recent years airborne laser scanning (ALS) evolved into a state‐of‐the‐art technology for topographic data acquisition. We present a novel, automatic method for water surface classification and delineation by combining the geometrical and signal intensity information provided by ALS. The reflection characteristics of water surfaces in the near‐infrared wavelength (1064 nm) of the ALS system along with the surface roughness information provide the basis for the differentiation between water and land areas. Water areas are characterized by a high number of laser shot dropouts and predominant low backscatter energy. In a preprocessing step, the recorded intensities are corrected for spherical loss and atmospheric attenuation, and the locations of laser shot dropouts are modeled. A seeded region growing segmentation, applied to the point cloud and the modeled dropouts, is used to detect potential water regions. Object‐based classification of the resulting segments determines the final separation of water and non‐water points. The water‐land‐boundary is defined by the central contour line of the transition zone between water and land points. We demonstrate that the proposed workflow succeeds for a regulated river (Inn, Austria) with smooth water surface as well as for a pro‐glacial braided river (Hintereisfernerbach, Austria). A multi‐temporal analysis over five years of the pro‐glacial river channel emphasizes the applicability of the developed method for different ALS systems and acquisition settings (e.g. point density). The validation, based on real time kinematic (RTK) global positioning system (GPS) field survey and a terrestrial orthophoto, indicate point cloud classification accuracy above 97% with 0·45 m planimetric accuracy (root mean square error) of the water–land boundary. This article shows the capability of ALS data for water surface mapping with a high degree of automation and accuracy. This provides valuable datasets for a number of applications in geomorphology, hydrology and hydraulics, such as monitoring of braided rivers, flood modeling and mapping. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

A macroseismic intensity prediction equation for intermediate depth earthquakes in the Vrancea region,Romania     

Mathilde B. Sørensen  Dietrich Stromeyer  Gottfried Grünthal 《Soil Dynamics and Earthquake Engineering》2010

The use of shake maps in terms of macroseismic intensity in earthquake early warning systems as well as intensity based seismic hazard assessments provides a valuable supplement to typical studies based on recorded ground motion parameters. A requirement for such applications is ground motion prediction equations (GMPE) in terms of macroseismic intensity, which have the advantages of good data availability and the direct relation of intensity to earthquake damage. In the current study, we derive intensity prediction equations for the Vrancea region in Romania, which is characterized by the frequent occurrence of large intermediate depth earthquakes giving rise to a peculiar anisotropic ground shaking distribution. The GMPE have a physical basis and take the anisotropic intensity distribution into account through an empirical regional correction function. Furthermore, the relations are easy to implement for the user. Relations are derived in terms of epicentral, rupture and Joyner–Boore distance and the obtained relations all provide a new intensity estimate with an uncertainty of ca. 0.6 intensity units.  相似文献   

Gamma-Rays and Neutrons as a Probe of Flare Proton Spectra: the Solar Flare of 11 June 1991     

Dunphy  Philip P.  Chupp  Edward L.  Bertsch  David L.  Schneid  Edward J.  Gottesman  Stephen R.  Kanbach  Gottfried 《Solar physics》1999,187(1):45-57

The large flare of 11 June 1991 (GOES class X12) was detected by the Total Absorption Shower Counter (TASC) segment of the EGRET gamma-ray telescope on board the Compton Gamma Ray Observatory. Significant gamma-ray emission was observed over the entire energy range to which the TASC was sensitive –1 to 140 MeV. Several phases were identified which showed major changes in the intensity and spectral shape of the flare gamma-rays. Furthermore, a 'delayed' phase during which a response consistent with the detection of energetic neutrons and pion-decay gamma-rays was seen, implying a qualitative change in the spectral shape of the accelerated ion spectrum. The similarity of the characteristics of this delayed phase (pion and energetic neutron production) to those in other large flares hint at a common particle acceleration mechanism.  相似文献