Lead orthophosphates—III. Stabilities of fluoropyromorphite and bromopyromorphite at 25°C     

Jerome O. Nriagu 《Geochimica et cosmochimica acta》1973,37(7):1735-1743

The reactions of secondary lead orthophosphate with approximately 10^?1 M sodium fluoride and sodium bromide solutions have been investigated at 25°C. Interpretation of the solubility data resulted in solubility product constants for fluoropyromorphite and bromopyromorphite of 10^?71.6 and 10^?78.1, respectively. According to these constants, the stability sequence for lead pyromorphites is Pb₅(PO₄)₃Cl > Pb₅(PO₄)₃Br > Pb₅(PO₄)₃OH > Pb₅(PO₄)₃F. The derived free energy data have been used to evaluate the respective stabilities of fluoro-pyromorphite and bromopyromorphite within the systems PbF₂-PbO-P₂O₅-H₂O and PbBr₂-PbO-P₂O₅-H₂O and to predict the equilibrium behavior of the Pb₅(PO₄)₃F-Pb₅(PO₄)₃OH solid solution under aqueous conditions.  相似文献   

Flexible Automatic Scheduling for Autonomous Telescopes: The MAJORDOME     

Mathieu Bringer  Michel Boër  Cedric Peignot  Gérard Fontan  Colette Mercé 《Experimental Astronomy》2001,12(1):33-48

We have developped a new method for the scheduling ofastronomical automatic telescopes, in the framework of theautonomous TAROT instrument. The MAJORDOME software canhandle a variety of observations, constrained, periodic,etc., and produces a timeline for the night, which may bemodified at any time to take into account the specificconditions of the night. The MAJORDOME can also handletarget of opportunity observations without delay.  相似文献   

Cloud height differences on Saturn     

Jerome Apt  Robert B. Singer 《Icarus》1982,52(3):503-508

Spectrophotometry from 0.6–2.5 μm at 1.5% spectral resolution of Saturn's equator and visibly dark South Equatorial Belt near a 1980 ring-plane crossing shows substantially less absorption by methane over the equator than over the SEB. Model fits using Appleby's model atmosphere and a multiple scattering model lead to the conclusion that the pressure levels of the clouds in the two regions differ by 20%. The region of high clouds is coincident with the location of the equatorial fast jet observed by Voyager.  相似文献   

西昆仑山前冲断带晚新生代构造地貌特征   总被引：5，自引：0，他引：5  

潘家伟  李海兵Jerome Van Der Woerd孙知明  裴军令Laurie Barrier 司家亮 《地质通报》2007,26(10):1368-1379

在卫片解译、DEM数据处理、地形图分析与剖面制作的基础上,结合野外构造地貌考察与观测,对西昆仑山前冲断带的构造地貌特征进行了定量、半定量的研究。沿山前发育系统的水系变化、冲积扇变化、不对称背斜、大规模正断裂、不对称河流阶地等典型的构造地貌,表明这条由南向北逆冲的冲断带在扩展过程中存在着由西向东迁移的特征。冲断带的东西分段以桑株河为界,以西发育固满背斜,其构造样式为向北的逆冲伴随向南的反冲;以东发育一系列不对称的背斜,表现出明显的由南向北逆冲的特征,地表无明显的反冲构造出现。利用生长地层和河流阶地估算了西昆仑山的隆升速率:晚上新世—早更新世以来的最低隆升速率为0.21～0.25mm/a,100ka以来的隆升速率为1.5mm/a。  相似文献   

A simple mass estimate for central black holes in cuspy galaxies     

Herwig Dejonghe  Anne Mathieu  Veronique De Bruyne  Sven De Rijcke 《Celestial Mechanics and Dynamical Astronomy》1998,72(3):219-233

We argue that the temperature of the stellar phase is likely a monotically decreasing function of radius in the central regions of elliptical galaxies with cusps. We show that it requires the presence of a central mass concentration. An estimate of its minimum mass based on few parameters is given. This lower bound is consistent with current mass values of the central objects in galaxies derived from detailed models. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Regional landslide evaluation: Two Utah examples   总被引：1，自引：0，他引：1  

Jerome V. DeGraff 《Environmental Geology》1978,2(4):203-214

Landslide-susceptibility evaluations based on bedrock units, slope inclination, and aspect (slope orientation) incorporate the lithologic, stratigraphic, structural, and topographic passive conditions contributing to landsliding as outlined by Sharpe (1938). Generalized results based on passive condition analyses may define potential for failure over entire states or large parts of states, establishing an approximate landslide susceptibility for specific areas that are still in need of detailed study. This provides a preliminary susceptibility for use in land management and identifies high-priority areas for future detailed investigations. Landslides in the Bear River Range, north-central Utah, and the northern Wasatch Plateau, central Utah, illustrate application of these factors to regional landslide-susceptability evaluation. The greatest landslide potential exists on slopes of between 10 and 40%, with a westerly aspect, underlain by Wasatch or Salt Lake formations in the Bear River Range and on slopes of from 20 to 60% that are underlain by either North Horn or Price River formations in the northern Wasatch Plateau. Results from the two study areas are compared to a statewide landslide evaluation (Schroder 1971) in terms of passive conditions. Lithologic and stratigraphic conditions of the state and of the two study areas are nearly identical. Aspect data detect the presence or absence of structural conditions favoring failure in the two study areas rather than climatic factors as concluded in the statewide analysis. Topographic condition is more precisely stated in quantitative as opposed to qualitative terms to define failure-prone slopes in the two study areas.  相似文献   

The occurrence of fungi on some rooted aquatics from the Chesapeake Bay     

Jerome J. Motta 《Estuaries and Coasts》1978,1(2):101-105

During 1975 and 1976, 433 isolates, representing 37 genera of fungi, were collected fromPotamogeton perfoliatus andRuppia maritima in the Chesapeake Bay. Seasonal distribution patterns of selected species are presented and their possible relationships to the declining host plant populations are discussed.  相似文献   

THE PALEOSEISMIC SURFACE RUPTURE AT SOUTH OF CENTRAL ALTYN TAGH FAULT AND ITS TECTONIC IMPLICATION          下载免费PDF全文

SHAO Yan-xiu  YUAN Dao-yang  LIU-ZENG Jing  Jerome Van der Woerd  LI Zhi-gang  WU Lei  LIU Fang-bin 《地震地质》1979,42(2):435-454

In this study, we described a 14km-long paleoearthquakes surface rupture across the salt flats of western Qaidam Basin, 10km south of the Xorkol segment of the central Altyn Tagh Fault, with satellite images interpretation and field investigation methods. The surface rupture strikes on average about N80°E sub-parallel to the main Altyn Tagh Fault, but is composed of several stepping segments with markedly different strike ranging from 68°N~87°E. The surface rupture is marked by pressure ridges, sub-fault strands, tension-gashes, pull-apart and faulted basins, likely caused by left-lateral strike-slip faulting. More than 30 pressure ridges can be distinguished with various rectangular, elliptical or elongated shapes. Most long axis of the ridges are oblique(90°N~140°E)to, but a few are nearly parallel to the surface rupture strike. The ridge sizes vary also, with heights from 1 to 15m, widths from several to 60m, and lengths from 10 to 100m. The overall size of these pressure ridges is similar to those found along the Altyn Tagh Fault, for instance, south of Pingding Shan or across Xorkol. Right-stepping 0.5~1m-deep gashes or sub-faults, with lengths from a few meters to several hundred meters, are distributed obliquely between ridges at an angle reaching 30°. The sub-faults are characterized with SE or NW facing 0.5~1m-high scarps. Several pull-apart and faulted basins are bounded by faults along the eastern part of the surface rupture. One large pull-apart basins are 6~7m deep and 400m wide. A faulted basin, 80m wide, 500m long and 3m deep, is bounded by 2 left-stepping left-lateral faults and 4 right-stepping normal faults. Two to three m-wide gashes are often seen on pressure ridges, and some ridges are left-laterally faulted and cut into several parts, probably owing to the occurrence of repetitive earthquakes. The OSL dating indicates that the most recent rupture might occur during Holocene.
Southwestwards the rupture trace disappears a few hundred meters north of a south dipping thrust scarp bounding uplifted and folded Plio-Quaternary sediments to the south. Thrust scarps can be followed southwestward for another 12km and suggest a connection with the south Pingding Shan Fault, a left-lateral splay of the main Altyn Tagh Fault. To the northeast the rupture trace progressively veers to the east and is seen cross-cutting the bajada south of Datonggou Nanshan and merging with active thrusts clearly outlined by south facing cumulative scarps across the fans. The geometry of this strike-slip fault trace and the clear young seismic geomorphology typifies the present and tectonically active link between left-lateral strike-slip faulting and thrusting along the eastern termination of the Altyn Tagh Fault, a process responsible for the growth of the Tibetan plateau at its northeastern margin. The discrete relation between thrusting and strike-slip faulting suggests discontinuous transfer of strain from strike-slip faulting to thrusting and thus stepwise northeastward slip-rate decrease along the Altyn Tagh Fault after each strike-slip/thrust junction.  相似文献   

Precipitation water storage capacity in a temperate mixed oak–beech canopy     

Frédéric André  Mathieu Jonard  Quentin Ponette 《水文研究》2008,22(20):4130-4141

The storage capacity of a temperate mixed oak–beech stand was investigated as a function of stand density and species composition. Measurements were performed in selected zones delimited by three neighbouring trees. Three independent approaches were compared: (i) a spraying laboratory experiment to estimate the water storage on foliage before and after dripping; (ii) a mechanistic model describing rainfall partitioning within the forest canopy and providing estimates of foliage storage capacities; and (iii) linear regression analyses to evaluate the canopy (foliage + branches) storage capacity using the relationship between throughfall and rainfall. Good agreement was generally observed between the laboratory experiment and the mechanistic model estimates, while estimations from the regression method tended to exceed those from the other approaches. Storage capacity estimates ranged from 0·22 mm to 0·80 mm for pure oak zones, from 0·24 mm to 1·12 mm for mixed zones and from 0·53 mm to 1·17 mm for pure beech zones. The increase of storage capacity with increasing proportion of beech in the canopy resulted from higher beech LAI compared with oak. Similarly, for mixed and pure beech canopies, storage capacity was higher for high density zones than for low density zones as a result of the increase in LAI with increasing local basal area; in contrast, for pure oak, the storage capacity was not related to basal area because of the lower shade‐tolerance of this species compared with beech. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

On the use of the generalised effective stress in the constitutive modelling of unsaturated soils     

Lyesse Laloui  Mathieu Nuth 《Computers and Geotechnics》2009,36(1-2):20-23

The definition of a consistent stress framework is an essential prerequisite to the constitutive modelling of unsaturated soils. It is proposed to clarify the effective stress lexicon commonly used for unsaturated soils, one of the purposes being to contribute to a more accurate definition and understanding of conventional Bishop’s stress. The so-called generalised effective stress is formulated on the basis of previous studies and set within a complete constitutive context. A point by point comparison between Bishop’s stress and generalised framework is led. The usual analogies between suction effects, cementation and hardening are also discussed. Suction is shown not to be a hardening variable but rather a shape parameter for the yield surface expressed in the matric suction versus mean effective stress plane. Some advantages of the generalised effective stress are finally reviewed, with a particular accent laid on the uniqueness of the yield limit and the built-in hydro-mechanical coupling.  相似文献