Indian Institute of Technology Indore

About: Indian Institute of Technology Indore is a education organization based out in Indore, Madhya Pradesh, India. It is known for research contribution in the topics: Fading & Support vector machine. The organization has 1606 authors who have published 4803 publications receiving 66500 citations.

Elimination of Ocular Artifacts From Single Channel EEG Signals Using FBSE-EWT Based Rhythms

Abstract: Electroencephalogram (EEG) is a diagnostic test, and it measures the entire brain’s electrical activity. The EEG signals have been used in many applications such as the diagnosis of neurological abnormalities, the brain-computer interface (BCI), the detection of sleep-related pathologies, etc. The EEG signal is contaminated with ocular artifact during the acquisition, and the filtering of this artifact is indeed required for efficient processing of this signal. In this work, we have proposed a method for the removal of ocular artifacts from the EEG signal. The Fourier-Bessel series expansion based empirical wavelet transform (FBSE-EWT) is used for the extraction of EEG rhythms namely, $\delta $ rhythm, $\theta $ rhythm, $\alpha $ rhythm, $\beta $ rhythm and $\gamma $ rhythm sub-signals from the ocular artifact contaminated EEG signal. The enhanced local polynomial (LP) approximation based total variation (TV) (LPATV) filtering is applied over the contaminated $\delta $ rhythm to obtain both LP and TV components. The filtered $\delta $ rhythm sub-signal is obtained based on the subtraction of both LP and TV components from the contaminated $\delta $ rhythm sub-signal. The filtered EEG signal is evaluated by combining the filtered $\delta $ rhythm with $\theta $ rhythm, $\alpha $ rhythm, $\beta $ rhythm, and $\gamma $ rhythm sub-signals. The energy ratio of the $\delta $ rhythm and the mean absolute error (MAE) in the power spectral density (PSD) values for all other rhythms are used as the performance metrics for the evaluation of the proposed method. The experimental results reveal that the proposed method has a better performance with a minimum average MAE in PSD value of 0.029 for $\alpha $ rhythm as compared to other existing techniques.

Surfactant-Induced Modulation of Nanometal Surface Energy Transfer from Silicon Quantum Dots to Silver Nanoparticles

Abstract: In the present study, we have demonstrated the excitation energy transfer (EET) from silicon quantum dots (Si QDs) to silver nanoparticles (Ag NPs) and its modulation in the presence of cetyltrimethylammonium bromide (CTAB) surfactant by means of steady-state and time-resolved photoluminescence (PL) spectroscopy. Significant spectral overlap between the emission spectrum of Si QDs and localized surface plasmon resonance of Ag NPs results in a substantial amount of PL quenching of Si QDs. In addition, the PL lifetime of Si QDs is shortened in the presence of Ag NPs. The origin of this PL quenching has been rationalized on the basis of increased nonradiative decay rate due to excitation energy transfer from Si QDs to Ag NPs surface. The observed energy-transfer efficiency correlates well with the nanometal surface energy transfer theory with a 1/d4 distance dependence rather than conventional Forster resonance energy transfer theory. It has also been observed that the EET efficiency drastically reduces in t...

Weakest Solar Cycle of the Space Age: A Study on Solar Wind–Magnetosphere Energy Coupling and Geomagnetic Activity

Abstract: Solar Cycle 24, from December 2008 to December 2019, is recorded to be the weakest in magnitude in the space age (after 1957) A comparative study of this cycle with Solar Cycles 20 through 23 is presented It is found that Solar Cycle 24 is not only the weakest in solar activity, but also in average solar wind parameters and solar wind–magnetosphere energy coupling This resulted in lower geomagnetic activity, lower numbers of high-intensity long-duration continuous auroral electrojet ( $AE$ ) activity (HILDCAA) events and geomagnetic storms The Solar Cycle 24 exhibited a $\approx 54$ – $61\%$ reduction in HILDCAA occurrence rate (per year), $\approx 15$ – $34\%$ reduction in moderate storms ( $-50~\text{nT} \geq Dst > -100~\text{nT}$ ), $\approx 49$ – $75\%$ reduction in intense storms ( $-100~\text{nT} \geq Dst > -250~\text{nT}$ ) compared to previous cycles, and no superstorms ( $Dst \leq -250~\text{nT}$ ) Implications of the solar and geomagnetic weakening to space weather science and operations are discussed