Artificial neural networks (ANNs) constitute a class of flexible nonlinear models designed to mimic biological neural systems. In this entry, we introduce ANN using familiar econometric terminology and provide an overview of ANN modeling approach and its implementation methods. † Correspondence: Chung-Ming Kuan, Institute of Economics, Academia Sinica, 128 Academia Road, Sec. 2, Taipei 115, Taiwan; ckuan@econ.sinica.edu.tw. †† I would like to express my sincere gratitude to the editor, Professor Steven Durlauf, for his patience and constructive comments on early drafts of this entry. I also thank Shih-Hsun Hsu and Yu-Lieh Huang for very helpful suggestions. The remaining errors are all mine.

Artificial neural networks

A comparison of methods to avoid overfitting in neural networks training in the case of catchment runoff modelling

A statistical point-process model is derived to describe the standard activity of earthquake occurrences by assuming that general seismicity is given by the superposition of aftershock sequences. The parameters are estimated ty the maximum likelihood method. Using the estimated model, the “residual point process” of the data is defined and used to find the anomalies which are included in the data set but not captured in the considered model for the standard seismicity. For instance, seismic quiescences can be measured quantitatively by using the residual process. Some examples are provided to illustrate such analyses. Furthermore, a time series of the magnitudes on the residual point process is considered, to investigate its dependence either on the time or on the history of the seismicity. By assuming the exponential distribution at each time and modelling of the b- value , we can examine such dependences and estimate them. Two practical examples are shown.

Statistical model for standard seismicity and detection of anomalies by residual analysis

Optimizing neural networks for river flow forecasting – Evolutionary Computation methods versus the Levenberg–Marquardt approach

Lightning produces electromagnetic fields and waves in all frequency ranges. In the extremely low frequency (ELF) range below 100 Hz, the global Schumann Resonances (SR) are excited at frequencies of 8 Hz, 14 Hz, 20 Hz, etc. This review is aimed at the reader generally unfamiliar with the Schumann Resonances. First some historical context to SR research is given, followed by some theoretical background and examples of the extensive use of Schumann resonances in a variety of lightning-related studies in recent years, ranging from estimates of the spatial and temporal variations in global lighting activity, connections to global climate change, transient luminous events and extraterrestrial lightning. Both theoretical and experimental results of the global resonance phenomenon are presented. It is our hope that this review will increase the interest in SR among researchers previously unfamiliar with this phenomenon.

https://www.mdpi.com/2073-4433/7/9/116/pdf

ELF Electromagnetic Waves from Lightning: The Schumann Resonances

Apart from diurnal and seasonal variations, integrated field intensity of sferics (IFIS) exhibits characteristic variations in relation to various geophysical and solar events like geomagnetic storms, meteor showers, solar X-ray flares and solar radio emission. Continuous monitoring of IFIS at frequencies 1, 3, 6, 9 and 12 kHz from Agartala (latitude 23oN) are being made over the last several years. The analyses of some preliminary observations in relation to solar flares are reported in the paper. Solar flare effects on the propagation of transmitted signals at 16.3 kHz recorded in Kolkata (latitude 22.56oN) during November 2004 have also been presented.

http://nopr.niscair.res.in/bitstream/123456789/6305/1/IJRSP%2038%285%29%20260-265.pdf

Some studies of solar flare effects on the propagation of sferics and a transmitted signal

Some experiments on July 22, 2009, the day of solar eclipse, were undertaken at Kolkata (latitude: 22.56° N, longitude: 88.5° E) to observe the effect of solar eclipse on various parameters of the atmospheric electricity which are directly related to global thunderstorm activity and solar irradiation. Significant changes are observed in their values during the eclipse period than their ambient values for the same period in the adjacent five days, which will be presented here along with their interpretation.

http://ieeexplore.ieee.org/iel5/5398767/5407062/05407075.pdf

Effects of solar eclipse of July 22, 2009 on VLF signals and atmospheric electricity parameters over Kolkata

The development of a neurocomputing technique to forecast the average winter shower in India has been modeled from 48 years of records (1950–1998). The complexities in the rainfall–sea surface temperature relationships have been statistically analyzed along with the collinearity diagnostics. The presence of multicollinearity has been revealed and a variable selection has been executed accordingly. The absence of persistence has also been revealed. For this reason, an Artificial Neural Net Model as a predictive tool for the said meteorological event in the form of a Multiple Layer Perceptron has been generated with a sea surface temperature anomaly and monthly average winter shower data over India during the above period. After proper training and testing, a Neural Net model with small prediction error is developed and the supremacy of the Artificial Neural Net over conventional statistical predictive procedures has been established statistically.

/pdf/forecasting-the-winter-shower-over-india-through-a-4qt9fwi8uv.pdf

Forecasting the winter shower over India through a neurocomputing approach

Generation of short-range gravity waves within the ionosphere due to inhomogenous heating in the presence of space-localized inhomogeneities during high-power radio wave-propagation has been investigated. The magnitude and from of the anticipated atmospheric wave-trains are obtained. The derived experession of electric field within the ionosphere under the stated perturbed condition may be considered to be manifested through Lorentz-force and Joule-dissipation that influence the neutral gas of the atmosphere via collision-mechanism and thereby gravity waves are launched. The expressions for the low-frequency part of the fractional pressure variations have been derived which are applied to theE-region of the ionosphere. The results are presented graphically.

Generation of gravity waves within the ionosphere by transient heating during high-power wave propagation

Some experiments on July 22, 2009, the day of solar eclipse, were undertaken at Kolkata (latitude: 2256° N, longitude: 885° E) to observe the effect of solar eclipse on various parameters of the atmospheric electricity which are directly related to global thunderstorm activity and solar irradiation Significant changes are observed in their values during the eclipse period than their ambient values for the same period in the adjacent five days, which will be presented here along with their interpretation

Syam Sundar De

Papers

Some studies of solar flare effects on the propagation of sferics and a transmitted signal

Effects of solar eclipse of July 22, 2009 on VLF signals and atmospheric electricity parameters over Kolkata

Forecasting the winter shower over India through a neurocomputing approach

Generation of gravity waves within the ionosphere by transient heating during high-power wave propagation

Effects of solar eclipse of July 22, 2009 on VLF signals and atmospheric electricity parameters over Kolkata