A prototype earthquake warning system for strike-slip earthquakes     

M. Nafi Toksöz  Anton M. Dainty  John T. Bullitt 《Pure and Applied Geophysics》1990,133(3):475-487

A prototype expert system has been developed to provide rapid warning of earthquakes while they are occurring. Warning times of up to 100 seconds will be possible. In the complete system, several accelerometers are distributed at intervals within a few kilometers of a known fault; data are telemetered to a central computer which implements the expert system. The expert system incorporates specific information about the type of fault to be monitored, and includes simple rules for estimating the fault slip, rupture length, and seismic moment, all in real time. If the seismic moment exceeds a preset value, an alarm may be issued. The prototype is designed for deployment on near-surface strike-slip faults such as the San Andreas and has been successfully tested with data from the 1979 Imperial Valley and 1984 Morgan Hill earthquakes. Crucial concepts have also been tested using synthetic data calculated for a model of the 1857 Fort Tejon earthquake. Parkfield, California, could be used as a test site.  相似文献   

Epiphytic orchids and their ecological niche under anthropogenic influence in central Himalayas,Nepal   总被引：1，自引：1，他引：0  

Yagya Prasad Adhikari  Anton Fischer  Hagen Siegfried Fischer 《山地科学学报》2016,13(5):774-784

The survival chance of epiphytic orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions.This study answers two questions:(1) What is the ecological niche of the different epiphytic orchid species?(2) What are the ecological factors that threaten epiphytic orchid's population under anthropogenic disturbances? Our study area was the Kathmandu valley,Nepal,with its subtropical forest.We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area,agricultural land,mixed agricultural and settled area,old tree patches,and a natural forest in a national park.The ecological niche of the orchid species was analyzed with a principal component analysis(PCA).The correlations between the different site factors were statistically significant.Spearman's rank correlation matrices showed that the variables land-use intensities with altitude,and height with diameter in breast height(dbh) of host had the highest significant positive correlation coefficient(0.67 and 0.64 respectively).On the other hand,host bark p H and altitude as well as land use had a significantly strong negative correlation coefficient(-0.80 and-0.61,respectively).Different epiphytic orchid species interact differently with the given set ofenvironmental factors:for occurrence of Vanda cristata there is no single environmental factor of special influence,while for Rhynchostylis retusa high bark p H and high light availability are important.First two axis of the PCA explained more than 50% of the total variance.Most orchid species occupy a specific,narrow niche in this ecological space.The main causes of anthropogenic influence of orchid population in the Kathmandu Valley are loss of adequate host trees(species and size) and increasing air pollution,resulting in increasing host bark p H.  相似文献   

Stresses and Displacements in Steel-Lined Pressure Tunnels and Shafts in Anisotropic Rock Under Quasi-Static Internal Water Pressure   总被引：1，自引：1，他引：0  

Alexandre J. Pachoud  Anton J. Schleiss 《Rock Mechanics and Rock Engineering》2016,49(4):1263-1287

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Calcite and dolomite in intrusive carbonatites. II. Trace-element variations     

Anton R. Chakhmouradian  Ekaterina P. Reguir  Christopher Couëslan  Panseok Yang 《Mineralogy and Petrology》2016,110(2-3):361-377

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The performance of collars on scour reduction at tandem piers aligned with different skew angles     

Sargol Memar  Aliasghar Beheshti  Majid Rahimpour  Giovanni De Cesare  Anton J. Schleiss 《Marine Georesources & Geotechnology》2020,38(8):911-922

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A model for the estimation of water filtration and nutrient regeneration by exposed sandy beaches     

Anton McLachlan 《Marine environmental research》1982,6(1):37-47

Exposed sandy beaches filter huge volumes of sea water daily as a result of wave and tide action. A regression model is developed which predicts the volume of water filtered daily by a beach as a function of tide range, beach slope and sand particle size. From these parameters estimates are also made of intertidal distance, the degree of expansion of the intertidal above the still water tide range by wave action and the average path length through the sand interstices percolated by filtered sea water. An equation is derived relating the degree of mineralisation of organic matter in the filtered sea water to the distance filtered through the sand and the sand particle size. Employing all this information, a simple model is used to estimate the volumes of sea water filtered and the amounts of inorganic nitrogen regenerated by intertidal sandy beaches over a range of physical conditions. The implications of this nutrient generation for the inshore zone are discussed.  相似文献   

Design of sediment detention basins: Scaled model experiments and application     

Anita Moldenhauer-Roth  Guillaume Piton  Sebastian Schwindt  Mona Jafarnejad  Anton JSchleiss 《国际泥沙研究》2021,36(1):136-150

Sediment detention basins are implemented on mountain rivers to trap solid material that may aggravate the flooding of downstream settlements.However,retention structures built in the past may unnecessarily retain sediment during non-hazardous flood events,resulting in high maintenance costs and sediment deficit downstream.In addition,the so-called spontaneous self-flushing of previously retained sediment during floods has occasionally been observed.Recent research suggests to design sediment detention basins for controlling sediment passage with a guiding channel across the deposition area upstream of a hybrid barrier.Such barriers consist of a check dam with a slot orifice and an upstream bar screen with a bottom clearance in order to benefit from a combined mechanical-hydraulic retention control.The present paper enhances this pioneering research with the help of new experimental data,including a wide range of sediment mixtures and large wood,as well as variable barrier heights.Improved design criteria are provided regarding the bar screen and the basin storage capacity.The functionality of the enhanced concept for sediment detention is illustrated by a case study on a physical model:the protection of the Villard-Bonnot village(France)against torrential hazards.  相似文献   

The emptiness of voids: yet another overabundance problem for the Λ cold dark matter model     

Anton V. Tikhonov  Anatoly Klypin 《Monthly notices of the Royal Astronomical Society》2009,395(4):1915-1924

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Modelling mean annual sediment yield using a distributed approach   总被引：3，自引：0，他引：3  

Anton J. J. Van Rompaey  Gert Verstraeten  Kristof Van Oost  Gerard Govers  Jean Poesen 《地球表面变化过程与地形》2001,26(11):1221-1236

In this paper a spatially distributed model for the calculation of sediment delivery to river channels is presented (SEDEM: SEdiment DElivery Model). The model consists of two components: (1) the calculation of a spatial pattern of mean annual soil erosion rates in the catchment using a RUSLE (Revised Soil Erosion Equation) approach; and (2) the routing of the eroded sediment to the river channel network taking into account the transport capacity of each spatial unit. If the amount of routed sediment exceeds the local transport capacity, sediment deposition occurs. An existing dataset on sediment yield for 24 catchments in central Belgium was used to calibrate the transport capacity parameters of the model. A validation of the model results shows that the sediment yield for small and medium sized catchments (10–5000 ha) can be predicted with an average accuracy of 41 per cent. The predicted sediment yield values with SEDEM are significantly more accurate than the predictions using a lumped regression model. Moreover a spatially distributed approach allows simulation of the effect of different land use scenarios and soil conservation techniques. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

OH defects in forsterite     

Eugen Libowitzky  Anton Beran 《Physics and Chemistry of Minerals》1995,22(6):387-392

Polarized FTIR spectra of near endmember forsterite single crystals from Pamir, Tadzikistan show the existence of sharp strongly pleochroic absorption bands in the region of the OH stretching fundamental. Bands centered at 3674/3624, 3647/3598 and 3640/ 3592 cm^-1 are attributed to OH dipoles oriented parallel to [100]. An OH band doublet at 3570/3535 cm^-1 shows both, a strong absorption parallel to [100] and a strong component parallel to [001]. On the basis of the pleochroic scheme and under the assumption of vacancies on Si- and M-sites it is proposed that O1 is partially replaced by OH defects pointing to the vacant Si-site. O3 is donator oxygen of OH dipoles lying near the O3-O1 tetrahedral edge or roughly pointing to a vacant M2-site. Also O2 can act as donator oxygen of an OH group oriented along the O2-O3 edge of a vacant M1 octahedron. The splitting of the bands is explained by the presence of Fe²⁺ in cation sites surrounding the OH defects.  相似文献