Collisions of low-energy antiprotons with molecular hydrogen: ionization, excitation and stopping power

A time-dependent coupled-channel approach was used to calculate ionization, excitation, and energy-loss cross sections as well as energy spectra for antiproton and proton collisions with molecular hydrogen for impact energies 8 keV < E < 4000 keV.Comment: 4 pages, 4 figures, conference LEAP0

Machine Learning Based Efficient Qt-Mtt Partitioning for VVC Inter Coding

The Joint Video Experts Team (JVET) have standardized the Versatile Video Coding (VVC) in 2020 targeting efficient coding of the emerging video services and formats such as 8K and immersive video streaming applications. VVC standard enhances the coding efficiency by 40% at the cost of an encoder computational complexity increase estimated to 859%(x8) compared to the previous standard High Efficiency Video Coding (HEVC). This work aims at reducing the complexity of the VVC encoder under the Random Access (RA) configuration. The proposed method takes advantage of the inter prediction in order to predict the split probabilities through a convolutional neural network. Our solution reaches 31.8% of complexity reduction for a negligible bitrate increase of 1.11% outperforming state-of-the-art methods.acceptedVersionPeer reviewe

Single-Active-Electron Approximation for Describing Molecules in Ultrashort Laser Pulses and Its Application to Molecular Hydrogen

A numerical approach that allows for the solution of the time-dependent Schr\uf6dinger equation TDSE describing molecules exposed to intense short laser pulses was developed. The molecular response to the strong field is described within the single-active electron approximation SAE. The method is applied in the fixed-nuclei approximation to molecular hydrogen with parallel orientation of the internuclear axis to the laser field. The validity of the SAE is investigated by comparing the ionization and electronic excitation yields to full two-electron solutions of the TDSE. The present results are also used to investigate the validity of approximate SAE methods like the molecular Ammosov-Delone-Krainov and the strong-field approximation

CNN Oriented Complexity Reduction Of VVC Intra Encoder

The Joint Video Expert Team (JVET) is currently developing the next-generation MPEG/ITU video coding standard called Versatile Video Coding (VVC) and their ultimate goal is to double the coding efficiency over the state-of-the-art HEVC standard.The latest version of the VVC reference encoder, VTM6.1, is able to improve the intra coding efficiency by 24 % over the HEVC reference encoder HM16.20, but at the expense of 27 times the encoding time. The complexity overhead of VVC primarily stems from its novel block partitioning scheme that complements Quad-Tree (QT) split with Multi-Type Tree (MTT) partitioning in order to better fit the local variations of the video signal. This work reduces the block partitioning complexity of VTM6.1 through the use of Convolutional Neural Networks (CNNs). For each 64 × 64 Coding Unit (CU), the CNN is trained to predict a probability vector that speeds up coding block partitioning in encoding. Our solution is shown to decrease the intra encoding complexity of VTM6.1 by 51.5% with a bitrate increase of only 1.45%.acceptedVersionPeer reviewe

Complexity Reduction Opportunities in the Future VVC Intra Encoder

The Joint Video Expert Team (JVET) is developing the next-generation video coding standard called Versatile Video Coding (VVC) and their ultimate goal is to double the coding efficiency over the current state-of-the-art standard HEVC without letting complexity get out of hand. This work addresses the complexity of the VVC reference encoder called VVC Test Model (VTM) under All Intra coding configuration. The VTM3.0 is able to improve intra coding efficiency by 21% over the latest HEVC reference encoder HM16.19. This coding gain primarily stems from three new coding tools. First, the HEVC Quad-Tree (QT) structure extension with Multi-Type Tree (MTT) partitioning. Second, the duplication of intra prediction modes from 35 to 67. And third, the Multiple Transform Selection (MTS) scheme with two new discrete cosine/sine transforms (DCT-VIII and DST-VII). However, these new tools also play an integral part in making VTM intra encoding around 20 times as complex as that of HM. The purpose of this work is to analyze these tools individually and specify theoretical upper limits for their complexity reduction. According to our evaluations, the complexity reduction opportunity of block partitioning is up to 97%, i.e., the encoding complexity would drop down to 3% for the same coding efficiency if the optimal block partitioning could be directly predicted. The respective percentages for intra mode reduction and MTS optimization are 65% and 55%. We believe these results motivate VVC codec designers to develop techniques that are able to take most out of these opportunities.acceptedVersionPeer reviewe