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31.
Arnold Rom 《Celestial Mechanics and Dynamical Astronomy》1970,1(3-4):301-319
A software package for Mechanized Algebraic Operations (MAO) is described. With MAO one is able to manipulate on the computer Poisson series in literal form. The system is operational; it has application in the fields of celestial mechanics, astrodynamics, and nonlinear mechanics. Besides describing the system, the present paper suggests various techniques to prepare problems such that they lend themselves for an automated treatment with MAO. Optimized implementation of the general subroutines is discussed. 相似文献
32.
Andrea Román-Sánchez Ana Laguna Tony Reimann Juan Vicente Giráldez Adolfo Peña Tom Vanwalleghem 《地球表面变化过程与地形》2019,44(10):2066-2080
Particles on soil-mantled hillslopes are subject to downslope transport by erosion processes and vertical mixing by bioturbation. Both are key processes for understanding landscape evolution and soil formation, and affect the functioning of the critical zone. We show here how the depth–age information, derived from feldspar-based single grain post-infrared infrared stimulated luminescence (pIRIR), can be used to simultaneously quantify erosion and bioturbation processes along a hillslope. In this study, we propose, for the first time, an analytical solution for the diffusion–advection equation to calculate the diffusivity constant and erosion–deposition rates. We have fitted this model to age–depth data derived from 15 soil samples from four soil profiles along a catena located under natural grassland in the Santa Clotilde Critical Zone Observatory, in the south of Spain. A global sensitivity analysis was used to assess the relative importance of each model parameter in the output. Finally, the posterior probability density functions were calculated to evaluate the uncertainty in the model parameter estimates. The results show that the diffusivity constant at the surface varies from 11.4 to 81.9 mm2 a-1 for the hilltop and hill-base profile, respectively, and between 7.4 and 64.8 mm2 a-1 at 50 cm depth. The uncertainty in the estimation of the erosion–deposition rates was found to be too high to make a reliable estimate, probably because erosion–deposition processes are much slower than bioturbation processes in this environment. This is confirmed by a global sensitivity analysis that shows how the most important parameters controlling the age–depth structure in this environment are the diffusivity constant and regolith depth. Finally, we have found a good agreement between the soil reworking rates proposed by earlier studies, considering only particle age and depth, and the estimated diffusivity constants. The soil reworking rates are effective rates, corrected for the proportion of particles actually participating in the process. © 2019 John Wiley & Sons, Ltd. 相似文献
33.
Herold M Román-Cuesta RM Mollicone D Hirata Y Van Laake P Asner GP Souza C Skutsch M Avitabile V Macdicken K 《Carbon balance and management》2011,6(1):13
Measuring forest degradation and related forest carbon stock changes is more challenging than measuring deforestation since
degradation implies changes in the structure of the forest and does not entail a change in land use, making it less easily
detectable through remote sensing. Although we anticipate the use of the IPCC guidance under the United Framework Convention
on Climate Change (UNFCCC), there is no one single method for monitoring forest degradation for the case of REDD+ policy.
In this review paper we highlight that the choice depends upon a number of factors including the type of degradation, available
historical data, capacities and resources, and the potentials and limitations of various measurement and monitoring approaches.
Current degradation rates can be measured through field data (i.e. multi-date national forest inventories and permanent sample
plot data, commercial forestry data sets, proxy data from domestic markets) and/or remote sensing data (i.e. direct mapping
of canopy and forest structural changes or indirect mapping through modelling approaches), with the combination of techniques
providing the best options. Developing countries frequently lack consistent historical field data for assessing past forest
degradation, and so must rely more on remote sensing approaches mixed with current field assessments of carbon stock changes.
Historical degradation estimates will have larger uncertainties as it will be difficult to determine their accuracy. However
improving monitoring capacities for systematic forest degradation estimates today will help reduce uncertainties even for
historical estimates. 相似文献
34.
Montero José-María Mínguez Román Fernández-Avilés Gema 《Journal of Geographical Systems》2018,20(1):27-55
Journal of Geographical Systems - House price prediction is a hot topic in the economic literature. House price prediction has traditionally been approached using a-spatial linear (or intrinsically... 相似文献
35.
André Deprit Jacques Henrard J. F. Price Arnold Rom 《Celestial Mechanics and Dynamical Astronomy》1969,1(2):222-251
Birkhoff's normalizing canonical transformation at an equilibrium of elliptic type with no internal resonance can be built explicitly and recursively, without partial inversions or substitutions, by means of Lie transforms.Invariant sections and ordinary families of periodic orbits for truncated normalized systems are analyzed in detail. 相似文献
36.
T. Mochales A. M. Casas E. L. Pueyo O. Pueyo M. T. Román A. Pocoví M. A. Soriano D. Ansón 《Environmental Geology》2008,53(5):1067-1077
A geophysical survey routine is proposed to detect underground cavities and dolines; it is based on the sequential application
of magnetic, low-frequency ground penetrating radar (GPR) and microgravity techniques. A case study near Zaragoza (Ebro valley,
Spain) demonstrates the applicability of these methods. The strong contrast of magnetic and electromagnetic properties (and
to a lesser scale, of density) between the doline filling and the surrounding stratified Tertiary and Quaternary rocks allows
the shape of filled cavities to be clearly outlined by these methods. 相似文献
37.
Despite the undeniable influence of the angle of seismic incidence on seismic demand, limited research has been performed to determine its effect when assessing the probabilistic seismic performance of a structure. Since the ground motion group size has a well-known significant effect on the variability of collapse risk, the joint effect of both the ground motion group size and the angle of seismic incidence on the estimation of collapse risk is investigated. Results show that the two variables have a different effect on the collapse risk estimates, with one affecting the bias in the expected value of the estimates and the other their variability. In order to ensure acceptable levels of variability and bias, practical proposals are made regarding the minimum number of records and angles of seismic incidence that should be considered. 相似文献
38.
Xavier Romão Raimundo Delgado João Guedes Aníbal Costa 《Bulletin of Earthquake Engineering》2010,8(1):91-118
An application of the EC8-3 procedure for safety assessment is presented herein. Besides testing the applicability of the
code procedure, this application aims to assess the consistency of the safety assessment results that are obtained. Based
on the application of the EC8-3 procedure, the study assesses if the different methods of analysis that are permitted lead
to similar safety results and identifies the factors that may affect these results. Furthermore, the results obtained by the
EC8-3 procedure are complemented by a probabilistic approach yielding their corresponding fragility values. By comparing the
D/C ratios and the probabilistic results, the application aims to determine if similar D/C ratios lead to similar probabilistic results. Furthermore, the application tries to determine if a correlation can be established
between the D/C ratios and the expected fragility values. 相似文献
39.
Eduardo Barretto de Figueiredo Alan Rodrigo Panosso Rangel Romão Newton La ScalaJr 《Carbon balance and management》2010,5(1):3
Background
Since sugarcane areas have increased rapidly in Brazil, the contribution of the sugarcane production, and, especially, of the sugarcane harvest system to the greenhouse gas emissions of the country is an issue of national concern. Here we analyze some data characterizing various activities of two sugarcane mills during the harvest period of 2006-2007 and quantify the carbon footprint of sugar production. 相似文献40.