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1.
Influence of earthquakes on the stability of slopes 总被引：2，自引：0，他引：2
Robert Hack Dinand Alkema Gerard A.M. Kruse Noud Leenders Lucia Luzi 《Engineering Geology》2007,91(1):4-15
Earthquakes are a major trigger for instability of natural and man-made slopes. Often the instability of slopes due to an earthquake causes more destruction and kills more people than the actual earthquake itself. A comparison is made between different methodologies to analyze the potential stability of slopes during earthquakes. Theoretically, it seems simple to calculate the stability of a slope during an earthquake. In reality, however, the stability is influenced by so many parameters that are either not known or which influence is so poorly known that a decent estimation of stability cannot be made. Offshore the situation is worse because proper data required for stability calculations are even less available than onshore. On- and offshore, erosion and weathering create continuously slopes that may become unstable during a future earthquake, offshore also sedimentation creates continuously new slopes. Another fundamental problem in stability analysis is the complicated and largely unknown behavior of seismic waves in three-dimensions in natural materials. The lack of accurate data and the unknown behavior of seismic waves in three-dimensions make estimations of slope stability during an earthquake unreliable. 相似文献
2.
Benthic meiofauna community composition at polluted and non-polluted sites in New Zealand intertidal environments 总被引：1，自引：0，他引：1
Meiofauna composition was investigated for six field sites, including polluted and non-polluted sites, within two regions (Auckland and Bay of Plenty) during winter (July-August 2004) in the North Island of New Zealand. Physico-chemical parameters were measured during the sampling period and meiofauna distribution and abundance were compared with these measured parameters. Analysis of meiofauna abundance indicated that foraminiferans, nematodes and ostracods were the taxa that contributed to the variability between field sites within the Auckland region. However, no clear taxa dominance was seen in the Bay of Plenty region. Comparison of meiofauna abundance and physico-chemical parameters was done using multivariate analysis (PRIMER). However, no clear relationships between the parameters were observed in any field site in either region. The Shannon-Weiner index of diversity did not show any clear differentiation between polluted and non-polluted field sites. Therefore, from the present study, the taxa or physico-chemical parameters used could not effectively characterise pollution at the investigated field sites. 相似文献
3.
H. R. B. Hack 《Theoretical and Applied Climatology》1961,11(1):60-69
Summary Solar radiation intensity has been recorded on a single trace strip chart potentiometer and integrated automatically. The integral can be printed at frequencies from minutes to hours as required. The performance of the integration equipment has been assessed by (1) comparing chart area expected from a calibration of the printed digital output with the area as measured by planimeter and (2) estimating the scatter in the relation of chart area to printed output per hour on a number of days over periods up to a month. The errors (95% limits) are about ±1 cal cm–2 for hourly values and ±4 cal cm–2 for daily values.
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Zusammenfassung Die Intensität der Sonnenstrahlung wurde mit einem selbstabgleichenden Millivoltschreiber registriert und automatisch integriert. Das Integral kann nach Bedarf über Zeiten von der Größenordnung von Minuten bis Stunden gebildet werden. Die Leistungsfähigkeit des Integrators wurde abgeschätzt 1. durch Vergleich der auf Grund der Eichung des Integrators aus seinen Angaben errechneten Fläche unter der Registrierkurve mit der planimetrierten Fläche und 2. durch Abschätzung der Streuung der Werte des Zusammenhanges zwischen den pro Stunde angegebenen Integratorwerten und der Fläche auf dem Registrierstreifen an einer Anzahl von Tagen aus Perioden von einer Dauer bis zu einem Monat. Der Fehler (bei einer Genauigkeitsgrenze von 95%) liegt bet ±1 cal cm–2 für Stundensummen und bei ±4 cal cm–2 für Tagessummen.
Résumé L'intensité du rayonnement solaire fut enregistrée par un millivoltmètre compensateur et intégrée automatiquement. L'intégration peut s'étendre à des temps allant de la minute à plusieurs heures. L'exactitude de l'intégrateur fut estimée 1) en comparant la surface résultant de ses indications à celle que l'on planimètre, et 2) en calculant la dispersion des écarts entre les valeurs données par heure par l'intégrateur et celles qui résultent de la planimétrie, cela pour un certain nombre de jours choisis dans des périodes pouvant atteindre le mois. L'erreur (pour un domaine de validité de 95%) est de ±1 cal cm–2 pour des sommations horaires, de ±4 cal cm–2 pour des sommations diurnes.
With 4 Figures 相似文献
4.
5.
Climate sensitivity of the NCAR Community Climate Model (CCM2) to horizontal resolution 总被引：3，自引：1，他引：3
The dependence on horizontal resolution of the climate simulated by the National Center for Atmospheric Research Community Climate Model (CCM2) is explored. Simulations employing R15, T21, T31, T42, T63, and T106 horizontal spectral truncations are compared. Parameters associated with the diagnostic cloud scheme are modified for each resolution to provide similar global average cloud radiative forcing at each resolution. Overall, as with earlier studies, there are large differences between the low resolution R15 and T21 simulations and the medium resolution T42 simulation. Many climate statistics show a monotonic signal with increasing resolution, with the largest variation occurring from low to medium resolution. Although the monotonic signal is often from the low resolution simulations toward atmospheric analyses, in some cases it continues beyond the analyses at the highest resolution. Where convergence occurs, it is not always to the atmospheric analyses, and the highest resolution simulations are not the best by all measures. Although many climate statistics converge, the processes that maintain the climate do not, especially when considered on a regional basis. The implication is that the finer scales are required to capture the nonlinear processes that force the medium scales. Overall, it appears that, at a minimum, T42 resolution is required, but higher resolution would be better. Applications at T42 should take into consideration how model errors indicated by these resolution signals might affect any findings.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
6.
We have studied a few optical spectra of the symbiotic star CH Cygni obtained in the period January 1990-June 1991, which indicate that a mild increase of activity occurred between July and December 1990. This increase of activity is confirmed by the IUE observations made in the same period. In fact, in this period of time, we have observed an increase of intensity of all the emission lines both in the optical and ultraviolet ranges and of the continuous ultraviolet flux.Based on observations obtained at the Observatory of Haute Provence (OHP) and on observations by the International Ultraviolet Explorer (IUE) collected at the Villafranca Satellite Tracking Station. 相似文献
7.
Yoji Kondo Margherita Hack John B. Hutchings George E. McCluskey Jr. Miroslav Plavec Ronald S. Polidan 《Astrophysics and Space Science》1975,38(2):353-358
High-resolution ultraviolet spectrophotometry of the complex close binary systemβ Lyrae was performed with the Princeton Telescope Spectrometer onCopernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with the resolution of 0.2 Å (far-ultraviolet) and 0.4 Å (mid-ultraviolet). The far-ultraviolet spectrum is completely dominated by emission lines indicating existence of high temperature plasma in this binary. The spectrum ofthis object is unlike any other object observed fromCopernicus. It is believed that this high temperature plasma results from dynamic mass transfer taking place in this binary. The current results are compared with the OAO-2 Wisconsin Experiment Package observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; theCopernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole. 相似文献
8.
Geophysics For Slope Stability 总被引：2，自引：0，他引：2
Robert Hack 《Surveys in Geophysics》2000,21(4):423-448
A pre-requisite in slope stability analyses is that the internal structure and the mechanical properties of the soil or rock mass of the slope, are known or can be estimated with a reasonable degree of certainty. Geophysical methods to determine the internal structure of a soil or rock mass may be used for this purpose. Various geophysical methods and their merits for slope stability analyses are discussed. Seismic methods are often the most suitable because the measurements depend on the mechanical properties that are also important in the mechanical calculation of slope stability analyses. Other geophysical methods, such as electromagnetic, electric resistivity, self-potential, and gravity methods, may be useful to determine the internal structure, but require a correlation of found boundaries with mechanical properties. 相似文献
9.
M. Hack 《Astrophysics and Space Science》1969,5(4):403-419
The spectrum of the peculiar Bp star HD 36916 has been studied on plates with dispersion 9.7 A/mm and compared with those of Aur, B3V andi And, B8V. A comparison of the observed contours of H, H and of the Balmer discontinuity D with those computed by Mihalas gives the following results: HD 36916: e=0.347, logg=3.8;i And: e=0.383, logg=3.2; Aur: e=0.302, logg=3.6. HD 36916 presents the characteristics of the Si-4200 stars: strong deficiency in helium and probably also in oxygen and nitrogen, strong excess of silicon and strontium; 3984 Hgii is present. Moreover this star also has characteristics which are not common to Si-4200 stars but rather to Mn stars: excess by a factor of ten of the elements of the iron group and an excess larger, probably of the order of 100, for manganese. The star is a member of the Sword subgroup of the Orion association. 相似文献
10.
A. C. Hack R. C. Dwyer G. Phillips S. Whalan H.-Q. Huang 《Australian Journal of Earth Sciences》2013,60(7-8):1071-1096
AbstractMagmatic-textured zircon from medium- to high-K calc-alkaline Warraweena Volcanics (WV) in two drill holes have yielded concordant U–Pb dates of 417?±?3.5 and 414?±?4.0?Ma and are interpreted as maximum emplacement ages. The Warraweena volcanics were previously considered to be either Neoproterozoic or Macquarie arc equivalents. Whole-rock εNdt values of these volcanics are +4.5 and +4.8. Along strike of the drill holes, Devonian zircon U–Pb ages (411?±?5.5?Ma) were obtained from coherent S-type rhyolite flows that have highly negative εNdt values (–7.9 and –7.8). These are a component of the Oxley volcanics. The ages of the Warraweena and Oxley volcanics are identical within uncertainty.The Oxley volcanics (OV) are interbedded with predominantly fine- to medium-grained metasedimentary and so imply a Lower Devonian deposition age for these host rocks. Based on their geophysical characteristics, the metasediments are widely distributed. These metasedimentary rocks yield a wide range of maximum depositional ages, from Early Devonian to earliest Ordovician–latest Cambrian, similar to the Cobar Basin. The absence of complex fabric development typical of Ordovician supracrustal rocks in the region, and conformity with the OV where observable suggest the widespread sedimentation was synchronous with rift-related volcanism in the Early Devonian.Regionally, the WV is temporally, geochemically and isotopically (εNd values) similar to the calc-alkaline Louth Volcanics located over 100?km to the southwest of the WV. Louth Volcanics define a complexly folded belt in geophysical data. Other potentially correlative Early Devonian igneous rocks occur in the nearby Cobar Superbasin and elsewhere in the eastern Lachlan Orogen and are considered to represent the products of a post-orogenic, nascent continental back-arc rift system. 相似文献