scholarly journals Climatic modeling of the distribution of Oxytropis triphylla (Fabaceae) by maximum entropy method

2018 ◽  
Vol 11 ◽  
pp. 00002
Author(s):  
Konstantin Baikov ◽  
Denis Krivenko

Predictive spatial models of the distribution of Oxytropis triphylla (Pall.) Pers. (Fabaceae), an endemic species of Baikal Siberia, were generated in MAXENT computer program using maximum entropy method. Long-term data of air temperatures for every month of the year were downloaded from the world database of open access WorldClim. Modeling was performed separately for minimum, average and maximum temperatures. Each variable contribution to the modeling was the basis to select the key variables having higher influence on the obtained models. The selected 10 key variables are the following: minimum temperatures of December and January; average temperatures of October, December, January and February; maximum temperatures of November, December, January and February. Then a model of the second level was calculated using only the ten key variables. There are three northern localities in the zone of adverse temperature effects: cape Malyi Cheremshanyi, Chencha and Sakhuli villages (all of them are in the Republic of Buryatia). It has been experimentally confirmed that the values of the key variables along the coasts of the Maloe More of Lake Baikal (Irkutskaya Oblast) are the most favorable for habitation of O. triphylla in this part of its range.

1996 ◽  
Vol 51 (5-6) ◽  
pp. 337-347 ◽  
Author(s):  
Mariusz Maćkowiak ◽  
Piotr Kątowski

Abstract Two-dimensional zero-field nutation NQR spectroscopy has been used to determine the full quadrupolar tensor of spin - 3/2 nuclei in serveral molecular crystals containing the 3 5 Cl and 7 5 As nuclei. The problems of reconstructing 2D-nutation NQR spectra using conventional methods and the advantages of using implementation of the maximum entropy method (MEM) are analyzed. It is shown that the replacement of conventional Fourier transform by an alternative data processing by MEM in 2D NQR spectroscopy leads to sensitivity improvement, reduction of instrumental artefacts and truncation errors, shortened data acquisition times and suppression of noise, while at the same time increasing the resolution. The effects of off-resonance irradiation in nutation experiments are demonstrated both experimentally and theoretically. It is shown that off-resonance nutation spectroscopy is a useful extension of the conventional on-resonance experiments, thus facilitating the determination of asymmetry parameters in multiple spectrum. The theoretical description of the off-resonance effects in 2D nutation NQR spectroscopy is given, and general exact formulas for the asymmetry parameter are obtained. In off-resonance conditions, the resolution of the nutation NQR spectrum decreases with the spectrometer offset. However, an enhanced resolution can be achieved by using the maximum entropy method in 2D-data reconstruction.


Geophysics ◽  
2003 ◽  
Vol 68 (4) ◽  
pp. 1417-1422 ◽  
Author(s):  
Danilo R. Velis

The distribution of primary reflection coefficients can be estimated by means of the maximum entropy method, giving rise to smooth nonparametric functions which are consistent with the data. Instead of using classical moments (e.g. skewness and kurtosis) to constraint the maximization, nonconventional sample statistics help to improve the quality of the estimates. Results using real log data from various wells located in the Neuquen Basin (Argentina) show the effectiveness of the method to estimate both robust and consistent distributions that may be used to simulate realistic sequences.


1987 ◽  
Vol 4 (1) ◽  
pp. 78-82 ◽  
Author(s):  
B. C. De Simone ◽  
F. De Luca ◽  
B. Maraviglia

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