The accuracy of standard enthalpies and entropies for phases of petrological interest derived from density-functional calculations     

Artur?BenisekEmail authorView author&#;s OrcID profile  Edgar?Dachs 《Contributions to Mineralogy and Petrology》2018,173(11):90

The internal energies and entropies of 21 well-known minerals were calculated using the density functional theory (DFT), viz. kyanite, sillimanite, andalusite, albite, microcline, forsterite, fayalite, diopside, jadeite, hedenbergite, pyrope, grossular, talc, pyrophyllite, phlogopite, annite, muscovite, brucite, portlandite, tremolite, and CaTiO₃–perovskite. These thermodynamic quantities were then transformed into standard enthalpies of formation from the elements and standard entropies enabling a direct comparison with tabulated values. The deviations from reference enthalpy and entropy values are in the order of several kJ/mol and several J/mol/K, respectively, from which the former is more relevant. In the case of phase transitions, the DFT-computed thermodynamic data of involved phases turned out to be accurate and using them in phase diagram calculations yields reasonable results. This is shown for the Al₂SiO₅ polymorphs. The DFT-based phase boundaries are comparable to those derived from internally consistent thermodynamic data sets. They even suggest an improvement, because they agree with petrological observations concerning the coexistence of kyanite?+?quartz?+?corundum in high-grade metamorphic rocks, which are not reproduced correctly using internally consistent data sets. The DFT-derived thermodynamic data are also accurate enough for computing the P–T positions of reactions that are characterized by relatively large reaction enthalpies (>?100 kJ/mol), i.e., dehydration reactions. For reactions with small reaction enthalpies (a few kJ/mol), the DFT errors are too large. They, however, are still far better than enthalpy and entropy values obtained from estimation methods.  相似文献   

Satellite estimates and subpixel variability of rainfall in a semi-arid grassland          下载免费PDF全文

Yong Chen  Jing Duan  Junling An  Huizhi Liu  Ulrich G?rsdorf  Franz H.Berger 《大气和海洋科学快报》2021,14(5):24-29

卫星估雨精度的不确定性受到当地降雨类型和像元内降雨非均匀性影响,而结合这两个关键因素开展半干旱草原卫星估雨的研究有限.2009年夏,我们在中国锡林郭勒半干旱草原用多部微雨雷达和雨量计构建了9 km卫星像元降雨观测网,观测了像元内降雨非均匀性(空间变异系数CV),并评估了卫星估雨精度.结果表明:(1)CV值受像元内平均降雨量,降雨类型,降雨云面积及移向等影响,如高Cv值的降雨过程大多为平均降雨量小,对流性降雨过程,降雨云边缘像元CV值较高;(2)TRMM 3B42V7卫星估雨产品适用性较好,CMORPH和PERSIANN次之,但TRMM 3B42V7易在半干旱草原湖泊处高估降雨.  相似文献   

Carbon costs and benefits of France’s biomass energy production targets     

Aude?ValadeEmail authorView author&#;s OrcID profile  Sebastiaan?Luyssaert  Patrick?Vallet  Sylvestre?Njakou Djomo  Ingride?Jesus Van Der Kellen  Valentin?Bellassen 《Carbon balance and management》2018,13(1):26

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Impact of different sampling rates on precise point positioning performance using online processing service     

Serdar Erol  Reha Metin Alkan  ?.Murat Ozulu  Veli Il?i 《地球空间信息科学学报》2021,24(2):302-312

In this study, the effect of different sampling rates (i.e. observation recording interval) on the Precise Point Positioning (PPP) solutions in terms of accurac...  相似文献   

Use of immunofluorescence technique in cultured fibroblasts from Mediterranean cetaceans as new "in vitro" tool to investigate effects of environmental contaminants     

Marsili L  Casini S  Bucalossi D  Porcelloni S  Maltese S  Fossi MC 《Marine environmental research》2008,66(1):151-153

The aim of the present study was to propose the immunofluorescence technique in cultured fibroblasts from Mediterranean cetaceans as a new "in vitro" tool to explore the susceptibility of these marine mammals to different xenobiotic compounds. The cell lines were cultured from integument biopsies of free-ranging and stranded cetaceans (dead within 12h). Using the indirect immunofluorescence assay, we detected endogenous proteins induced by different contaminants. Here we present the method used for qualitative and quantitative evaluation of cytochromes P450 (CYP1A1 and CYP2B) induced by some POPs (DDTs and PCBs) and emerging contaminants (PBDEs) in fibroblast cell cultures of striped dolphin (Stenella coeruleoalba) and bottlenose dolphin (Tursiops truncatus). Immunofluorescence was quantified with a specially designed Olympus macro, DetectIntZ. A major result was the possibility of using this "in vitro" assay to quantify induction of endogenous proteins.  相似文献   

Evidence for the 8,200 a <Emphasis Type="SmallCaps">b</Emphasis>.<Emphasis Type="SmallCaps">p</Emphasis>. cooling event in the middle Okinawa Trough     

Hua?YuEmail author  Yingqian?Xiong  Zhenxia?Liu  Serge?Berné  Chi-Yue?Huang  Guodong?Jia 《Geo-Marine Letters》2008,28(3):131-136

Based on new and existing data on oxygen isotopes, alkenone-surface seawater temperature trends, planktonic foraminifers, lithology, and clay mineral composition of piston cores, a distinct cooling event has been identified around 8,200 cal a b.p. in the middle Okinawa Trough, northwest Pacific. This corresponds to the 8,200 a b.p. cooling event recorded in many places of the Northern Hemisphere. During this event, the local temperature decreased by 1°C, and the δ¹⁸O value increased by 0.6‰. A strengthened Asian winter monsoon is the most probable cause for this event, which thus adds further credibility to the contention that we are dealing here with a global phenomenon.  相似文献   

Evidence of hyperpycnal flows at the head of the meandering Kaoping Canyon off SW Taiwan     

Cheng-Shing?ChiangEmail author  Ho-Shing?Yu 《Geo-Marine Letters》2008,28(3):161-169

Using seismic and Chirp sonar profiles, this paper tests the hypothesis that hyperpycnal flows are the main factor controlling the formation and maintenance of the meandering Kaoping submarine canyon off SW Taiwan. Cross-section geometries, and erosional as well as depositional features vary along the canyon course. In the proximal, sinuous part of the canyon, down-cutting into the shelf strata has created a relief of 340 m. The cause of this intense erosion of the seafloor is suggested to be the frequent development of hyperpycnal flows. A seismic section across a meander in the distal part of the canyon shows levees formed by overspilled sediments at the outer bend, and a terrace characterized by relatively flat stratified facies at the inner bend. The geological setting and climatic conditions in SW Taiwan (e.g. earthquakes, typhoons, floods), as well as major river–canyon connections (for example, direct input of highly concentrated suspended sediment) would all promote hyperpycnal flow generation. This causes axial incision, canyon wall slumping, and the formation of levees by spill-over deposition in the upper reach of the Kaoping Canyon.  相似文献   

Sediment resuspension events induced by the wake wash of deep-draft vessels     

Erwan?GarelEmail author  Laura?López Fernández  Mike?Collins 《Geo-Marine Letters》2008,28(4):205-211

Hydrodynamics and sediment resuspension events, induced at the shoreline by a deep-draft vessel passing nearby, are described. Measurements (pressure, currents and turbidity) were obtained at 4 Hz, on a lower beach ~50 m from a channel where large car ferries operate in Wootton Creek, Isle of Wight. The study focuses on a representative 8-min 32-s-long record, during which two large vessels passed the channel section. At the shore, the passage of each vessel induced a long-period water-level drawdown, followed by a water-level oscillation (seiche) of similar period, and the short-period waves of the wake. Both drawdowns were the main constituents of the prevailing wave pattern. The second drawdown was the largest in amplitude, in response to a higher speed of the ferry, and the influence of the seiche which had been activated during the preceding event. Two successive peaks of turbidity were observed shortly after this drawdown. Analyses of current velocity and direction indicate that the sediments resuspended originated from the shallower upper beach. Anthropogenically induced erosion of the foreshore is predicted at Wootton Creek.  相似文献   

A real-time, event-triggered storm surge forecasting system for the state of North Carolina   总被引：3，自引：0，他引：3  

Craig Mattocks  Cristina Forbes   《Ocean Modelling》2008,25(3-4):95-119

A new real-time, event-triggered storm surge prediction system has been developed for the State of North Carolina to assist emergency managers, policy-makers and other government officials with evacuation planning, decision-making and resource deployment during tropical storm landfall and flood inundation events. The North Carolina Forecast System (NCFS) was designed and built to provide a rapid response assessment of hurricane threat, accomplished by driving a high-resolution, two-dimensional, depth-integrated version of the ADCIRC (Advanced Circulation) coastal ocean model with winds from a synthetic asymmetric gradient wind vortex. These parametric winds, calculated at exact finite-element mesh node locations and directly coupled to the ocean model at every time step, are generated from National Hurricane Center (NHC) forecast advisories the moment they are inserted into the real-time weather data stream, maximizing the number of hours of forecast utility. Tidal harmonic constituents are prescribed at the open water boundaries and applied as tidal potentials in the interior of the ocean model domain. A directional surface roughness parameterization that modulates the wind speed at a given location based on the types of land cover encountered upwind, a forest canopy sheltering effect, and a spatially varying distribution of Manning’s–n friction coefficient used for computing the bottom/channel bed friction are also included in the storm surge model. Comparisons of the simulated wind speeds and phases against their real meteorological counterparts, of model elevations against actual sea surface elevations measured by NOAA tide gauges along the NC coast, and of simulated depth-averaged current velocities against Acoustic Doppler Current Profiler (ADCP) data, indicate that this new system produces remarkably realistic predictions of winds and storm surge.  相似文献   

A spatiotemporal calculus for reasoning about land-use trajectories   总被引：1，自引：0，他引：1  

Adeline Marinho Maciel  Gilberto Camara  Lubia Vinhas  Michelle Cristina Araújo Picoli  Rodrigo Anzolin Begotti  Luiz Fernando Ferreira Gomes de Assis 《International journal of geographical information science》2019,33(1):176-192

Earth observation images are a powerful source of data about changes in our planet. Given the magnitude of global environmental changes taking place, it is important that Earth Science researchers have access to spatiotemporal reasoning tools. One area of particular interest is land-use change. Using data obtained from images, researchers would like to express abstractions such as ‘land abandonment’, ‘forest regrowth’, and ‘agricultural intensification’. These abstractions are specific types of land-use trajectories, defined as multi-year paths from one land cover into another. Given this need, this paper introduces a spatiotemporal calculus for reasoning about land-use trajectories. Using Allen’s interval logic as a basis, we introduce new predicates that express cases of recurrence, conversion and evolution in land-use change. The proposed predicates are sufficient and necessary to express different kinds of land-use trajectories. Users can build expressions that describe how humans modify Earth’s terrestrial surface. In this way, scientists can better understand the environmental and economic effects of land-use change.  相似文献