maximum entropy method
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MAUSAM ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 37-46
Author(s):  
D. V. BHASKAR RAO ◽  
C. V. NAIDU ◽  
B. R. SRINIVASA RAO

The data of the monthly cyclone frequencies over North Indian Ocean for the period 1877-1998 has been analysed to study the long-term trends and fluctuations. Analysis has been made separately for depressions and cyclones for the pre-monsoon, monsoon and post-monsoon seasons along with the annual frequencies. The data was subjected to 11-year moving averages and the epochs of increasing and decreasing trends have been identified. A consistent decreasing trend after 1950s is a notable feature.   The time series of the monthly cyclone frequency were passed through a high-pass filter to eliminate periods greater than 21 years and then subjected to spectrum analysis using Maximum Entropy Method to obtain dominant periodicities. Three significant periodicities at 2.2-2.8; 3.5-6.5 and 10-15 years have been identified which could be attributed to QBO, ENSO and decadal frequencies.


MAUSAM ◽  
2021 ◽  
Vol 57 (4) ◽  
pp. 597-608
Author(s):  
R. P. KANE

lkj & o"kZ 1900&2000 dh vof/k esa vVykafVd egklkxj dh rwQkuh xfrfof/k ¼ftUgas rwQku] izpaM rwQku] vkfn uke fn, x, gaS½ ds fofHkUu lwpdkadksa ds dky Jsf.k;ksa dk vuqØe fo’ys"k.k ,e-b-,e-¼vf/kdre ,uVªkWih fof/k½ }kjk rFkk mldh vkofrZrk ds vk;ke ,e- vkj- ,- ¼cgqq lekJ;.k fo’ys"k.k½ }kjk izkIr fd, x, gaSA fiNys dqN o"kksZa ds vkadM+ksa ¼o"kZ 1950 ls vkxss½ ds vuqlkj budh egRoiw.kZ vkofrZrk,¡ n’kd lfgr( f}okf"kZd dYi] f=okf"kZd dYi {ks=ksa rFkk buls mPp {ks=ksa esa Hkh jghA 2-40 o"kkasZ esa 50 feyhckj ds fuEu v{kka’k {ks=h; iou vkSj 2-40 ,oa 2-85 o"kkasZ ds b- ,u- ,l- vks- ¼,y uhuks/nf{k.kh nksyu½ ?kVuk ds ln`’k f}o"khZ dYi nksyu {ks= esa ¼3&4 o"kkasZ½ rwQku lwpdkad 2-40 rFkk 2-85 o"kksZa ds djhc pje ij jgsA mPp vkofrZrk okys {ks=ksa esa rwQku lwpdkad 4-5&5-5-] 8&9] 11&12 rFkk 14&15 o"kkasZ esa pje ij jgs tcfd b- ,u- ,l- vks- 7-4 ,oa 12&14 o"kksZa esa pje ij jgsA cgq n’kdh; Js.kh esa 28&34]40]50&53]61&63]~70 ,oa ~80 o"kksZa esa ¼ijUrq fHkUu lwpdkadksa ds fy, fHkUu&fHkUu½ rwQku pje ij jgs tks LFky ,oa leqnzh lrg ds rkiekuksa ds leku pje ekuksa ds vuq:Ik jgsA dqy lwpdkadksa esa 90 o"kkZsa esa yxHkx 50 izfr’kr dh m/oZ izo`fr jghA     The time series of the various indices of Atlantic storm activity (number of named storms, hurricanes, etc.) for 1900-2000 were subjected to spectral analysis by MEM (Maximum Entropy Method) and amplitudes of the periodicities were obtained by MRA (Multiple Regression Analysis).  For recent data (1950 onwards), significant periodicities were in the quasi-biennial, quasi-triennial regions and also in higher regions, including decadal. In the QBO region (2-3 years), storm indices had peaks near 2.40 and 2.85 years, similar to 2.40 years of 50 hPa low latitude zonal wind and 2.40 and 2.85 years of ENSO (El Niño/Southern Oscillation) phenomenon. In the QTO region (3-4 years), storm indices and ENSO had common peaks near 3.5 years. In higher periodicity regions, storm indices had peaks at 4.5-5.5, 8-9, 11-12 and 14-15 years, while ENSO had peaks at 7.4 and 12-14 years. In the multi-decadal range, storm peaks were at 28-34, 40, 50-53, 61-63, ~70 and ~80 years (but different for different indices), which matched with similar peaks in land and sea surface temperatures. Some indices had large uptrends, ~50% in 90 years.


2021 ◽  
Author(s):  
Sheila Valéria Álvares-Carvalho ◽  
Thiago Roberto Soares Vieira ◽  
Bruno Antonio Lemos de Freitas ◽  
Erica Moraes Santos de Souza ◽  
Laura Jane Gomes ◽  
...  

Abstract Hancornia speciosa is the target of research on genetic diversity, ethnobotanical and medicinal studies. However, information on the genetic variability of populations associated with modeling the potential distribution in the state of Sergipe has not yet been performed. The objective of this study was to predict the potential occurrence of H. speciosa in areas of high use of their fruits. The maximum entropy method was used to detect the distribution patterns of H. speciosa in variable environments. The diversity of four natural populations, situated in areas of extractivist, was determined by ISSR molecular markers. The species occurs more densely in the coastal regions of Sergipe. The prediction of occurrence indicates that the species reduces areas of occurrence, mainly due to anthropic actions. It is suggested that the species needs public policies aimed at its conservation and the priority populations for conservation.


Author(s):  
Dennis Wiedemann

Abstract In recent years, one-particle potentials (OPPs) derived from neutron-diffraction data have become a popular means to estimate activation energies of ion migration in solids. Computer programs for their calculation, however, have mostly been private in-house solutions. The software CalcOPP presented herein permits calculating two- or three-dimensional OPPs either from probability density functions put out by the crystallographic suite Jana2006/ Jana2020 (including error maps) or from scattering-density maps reconstructed using the maximum entropy method (MEM) implementation Dysnomia. The title program is open-source, written in modern free-form Fortran and Python 3, and available free of charge under the permissive MIT License. Executables are published for 64-bit Microsoft Windows and Linux platforms and can be controlled via an intuitive graphical user interface or via command-line interface. Depending on the kind of input, CalcOPP’s output is readily visualized with standard crystallographic software or plotting applications. The release of the program not only makes the rather powerful OPP method more transparent, but it also opens it up to a broader, less programming-oriented public.


2021 ◽  
Author(s):  
Andri A Wibowo

The discovery of a new prehistoric species of the genus Homo remains a significant matter of intense interest. One of significant discovery recently is the Homo floresiensis, representing a small-bodied and small-brained hominin, excavated, and found in Liang Bua Cave in Flores Island, East Nusa Tenggara, Indonesia. This species height was only about 106 cm (3'6") and the weight was 30-40 kg (66-86 lbs). H. floresiensis was known consumed extant murine rodents as its diets as this was evidence found in Liang Bua Cave. Then this study aims to model the H. floresiensis suitable habitat using maximum entropy method and 2 extant murine rodents, Rattus exulans and R. rattus as a proxy. The results show that the most suitable habitats for H. floresiensis indicated by suitable habitat values close to 1 were concentrated in the central of Flores Island that was overlapped with mountainous areas with elevation ranging from 1500 to 2000 m. These suitable habitats were also overlapped with dense vegetation covers, volcanic rock, and Kiro rock formation. Climatic parameters that limit the distributions of H. floresiensis were annual mean temperature, isothermality, minimum temperature of coldest period, and precipitation seasonality. Parts of Flores Island with the low temperature below 20 0C were favorable for H. floresiensis while an increase in isothermality limits the H. floresiensis distributions


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