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91.
92.
Determinations of reactive oxygen-containing functional groups were performed by usual chemical derivatization methods of four humic acids isolated from soils and deltaic sediments. Statistical tests and calculations based on elemental analysis demonstrated the validity and limits of these techniques and allowed us to identify from 60 to 71% of the total humic oxygen. Oxygen budgets of humic acids are discussed. 相似文献
93.
Extensive functional group analyses were performed on humic acids representative of eight increasing depth levels from a core drilled in the Mahakam delta (East Kalimantan, Indonesia). Oxygen amounts decrease observed during early diagenesis was related chiefly to loss of hydroxyl (lignol?) groups. Comparison between upper and deeper levels shows the following variations: hydroxyl group abundances go from 19 to 6% of humic oxygen. Identified functional groups amounts represent 47 to 32% of weight of moisture- and ash-free humic acids. No evidence of decarboxylation of humic material was detected. 相似文献
94.
There is strong evidence indicating that the six commonly recognized varieties of asbestos are cancer-producing agents Epidemiological
and experimental data indicate that, although response to inhalation exposure is most marked, exposure by ingestion probably
also entails a risk of excess tumor incidence. The toxicity of mineral fibers can be related to fiber dimensions, mineralogy,
chemistry, and surface-active properties.
In the Silver Lake Reservoir in Staten Island, New York, where chrysotile from serpentinite bedrock exposures is a potential
source of contamination, chrysotile asbestos levels of 15 to 86 million fibers per liter (MFL) were measured, with an average
of 53 MFL Much lower levels (average 0 3 MFL) were observed in small lakes and ponds with clayey bottoms on the Staten Island
Serpentinite. 相似文献
95.
A model is given of the magnetic-field equilibrium and possible dynamic excitations of a solar coronal arcade. Such structures are well observed in the spectral range from H to X-rays and often give rise to two-ribbon flares. However, the preflare state must be stable to ideal magnetohydrodynamic disturbances, and we treat this problem with particular attention to the necessary foot-point boundary conditions. Having devised a reasonably general perturbation set, we use an energy-principle analysis to show the strong stabilizing influence of inertial field-line tying at the photosphere.Address from October 1981: Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 400005, India. 相似文献
96.
Accounting for Spatial Uncertainty in Optimization with Spatial Decision Support Systems 总被引:2,自引:0,他引:2
Jeroen C. J. H. Aerts Michael F. Goodchild & Gerard B. M. Heuvelink 《Transactions in GIS》2003,7(2):211-230
Spatial decision support systems (SDSS) are designed to make complex resource allocation problems more transparent and to support the design and evaluation of allocation plans. Recent developments in this field focus on the design of allocation plans using optimization techniques. In this paper we analyze how uncertainty in spatial (input) data propagates through, and affects the results of, an optimization model. The optimization model calculates the optimal location for a ski run based on a slope map, which is derived from a digital elevation model (DEM). The uncertainty propagation is a generic method following a Monte Carlo approach, whereby realizations of the spatially correlated DEM error are generated using 'sequential Gaussian simulation'. We successfully applied the methodology to a case study in the Austrian Alps, showing the influence of spatial uncertainty on the optimal location of a ski run and the associated development costs. We also discuss the feasibility of routine incorporation of uncertainty propagation methodologies in an SDSS. 相似文献
97.
为了研究青藏高源东北部块体构造变形的深部驱动机制,笔者对青藏高原东北部的天然地震观测数据进行地震层析反演,并结合同一剖面的接收函数及各向异性结果进行讨论。介绍了ACH方法的基本原理,论述了由于印度板块向北俯冲的强大的持续作用力,造就了NE向俯冲到柴达木盆地之下的昆仑造山带,并发现在巴颜喀拉地体下方壳幔内的仰冲活动。壳幔内的低速体十分显著地出现在阿尼玛卿缝合线以北,深度可达300km。推断该低速体可能与昆仑断裂的深层的剪切作用有关。深部资料显示该区莫霍界面由北向南逐渐加深,这与青藏高原东北部的岩石圈减薄现象一致,而且与印度板块向北运动的远程效应有关。另外,地震层析结果及各向异性分析也支持青藏高原东北部主应力方向转为NE向的观点。 相似文献
98.
A transmission + reflection wave-equation traveltime and waveform inversion method is presented that inverts the seismic data for the anisotropic parameters in a vertical transverse isotropic medium. The simultaneous inversion of anisotropic parameters and ε is initially performed using transmission wave-equation traveltime inversion method. Transmission wave-equation traveltime only provides the low-intermediate wavenumbers for the shallow part of the anisotropic model; in contrast, reflection wave-equation traveltime estimates the anisotropic parameters in the deeper section of the model. By incorporating a layer-stripping method with reflection wave-equation traveltime, the ambiguity between the background-velocity model and the depths of reflectors can be greatly mitigated. In the final step, multi-scale full-waveform inversion is performed to recover the high-wavenumber component of the model. We use a synthetic model to illustrate the local minima problem of full-waveform inversion and how transmission and reflection wave-equation traveltime can mitigate this problem. We demonstrate the efficacy of our new method using field data from the Gulf of Mexico. 相似文献
99.
Ivar R. Lokhorst Sjoukje I. de Lange Gerard van Buiten Sanja Selaković Maarten G. Kleinhans 《地球表面变化过程与地形》2019,44(14):2922-2935
Landscape experiments of fluvial environments such as rivers and deltas are often conducted with live seedlings to investigate effects of biogeomorphological interactions on morphology and stratigraphy. However, such experiments have been limited to a single species, usually alfalfa (Medicago sativa), whereas important environments in nature have many different vegetation types and eco-engineering effects. Landscape experimentation would therefore benefit from a larger choice of tested plant species. For the purpose of experimental design our objective was to identify fast-germinating and fast-growing species and determine their sensitivity to flow conditions during and after settling, their maximum growth, hydraulic resistance and added bank strength. We tested germination time and seedling growth rate of 18 candidate species with readily available seeds that are fast growing and occur at waterlines, plus Medicago sativa as a control. We selected five species that germinate and develop within days and measured properties and eco-engineering effects depending on plant age and density, targeting typical experimental conditions of 0–0.3 m/s flow velocity and 0–30 mm water depth. Tested eco-engineering effects include bank strength and flow resistance. We found that Rumex hydrolapathum can represent riparian trees. The much smaller Veronica beccabunga and Lotus pedunculatus can represent grass and saltmarsh species as they grow in dense patches with high flow resistance but are readily erodible. Sorghum bicolor grows into tall, straight shoots, which add significantly to bank strength, but adds little flow resistance and may represent sparse hardwood trees. Medicago sativa also grows densely under water, suggesting a use for mangroves and perhaps peat. In stronger and deeper flows the application of all species changes accordingly. These species can now be used in a range of landscape experiments to investigate combined effects on living landscape patterns and possible facilitation between species. The testing and treatment methodology can be applied to new species and other laboratory conditions. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd. © 2019 The Authors Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd © 2019 The Authors Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd. 相似文献
100.
John D. Monnier Stefan Kraus Michael J. Ireland Fabien Baron Amelia Bayo Jean-Philippe Berger Michelle Creech-Eakman Ruobing Dong Gaspard Duchêne Catherine Espaillat Chris Haniff Sebastian Hönig Andrea Isella Attila Juhasz Lucas Labadie Sylvestre Lacour Stephanie Leifer Antoine Merand Ernest Michael Stefano Minardi Christoph Mordasini David Mozurkewich Johan Olofsson Claudia Paladini Romain Petrov Jörg-Uwe Pott Stephen Ridgway Stephen Rinehart Keivan Stassun Jean Surdej Theo ten Brummelaar Neal Turner Peter Tuthill Kerry Vahala Gerard van Belle Gautam Vasisht Ed Wishnow John Young Zhaohuan Zhu 《Experimental Astronomy》2018,46(3):517-529
The Planet Formation Imager (PFI, www.planetformationimager.org) is a next-generation infrared interferometer array with the primary goal of imaging the active phases of planet formation in nearby star forming regions. PFI will be sensitive to warm dust emission using mid-infrared capabilities made possible by precise fringe tracking in the near-infrared. An L/M band combiner will be especially sensitive to thermal emission from young exoplanets (and their disks) with a high spectral resolution mode to probe the kinematics of CO and H2O gas. In this paper, we give an overview of the main science goals of PFI, define a baseline PFI architecture that can achieve those goals, point at remaining technical challenges, and suggest activities today that will help make the Planet Formation Imager facility a reality. 相似文献