Energy-guided Entropic Neural Optimal Transport

Energy-Based Models (EBMs) are known in the Machine Learning community for the decades. Since the seminal works devoted to EBMs dating back to the noughties there have been appearing a lot of efficient methods which solve the generative modelling problem by means of energy potentials (unnormalized likelihood functions). In contrast, the realm of Optimal Transport (OT) and, in particular, neural OT solvers is much less explored and limited by few recent works (excluding WGAN based approaches which utilize OT as a loss function and do not model OT maps themselves). In our work, we bridge the gap between EBMs and Entropy-regularized OT. We present the novel methodology which allows utilizing the recent developments and technical improvements of the former in order to enrich the latter. We validate the applicability of our method on toy 2D scenarios as well as standard unpaired image-to-image translation problems. For the sake of simplicity, we choose simple short- and long- run EBMs as a backbone of our Energy-guided Entropic OT method, leaving the application of more sophisticated EBMs for future research

Studies of seismic effects on snow stability on mountain slopes

Studies of seismicity caused by technological explosions at mines in the Khibini Mountains and its influence on snow stability and avalanche releases began five years ago. First quantitative assessments of such influence were obtained during this time. It has been shown that there is a statistically significant correlation between seismic events and avalanche releases. Special seismic measurements to evaluate shaking effects of explosions have been carried out. The most interesting results of the measurements are described. At least two factors caused by shaking decrease snow stability-1) Inertia (decreases friction and increases downhill force), and 2) Snow strength decrease. Deterministic and stochastic models describing the influence of the first factor are presented. A shaking table designed to study seismic influence on snow shear strength, as well as first results obtained with it, are described. Directions of future studies are outlined. The work was supported by RFBR grants: 04-05-65057-a; 05-05-64037-a; 05-05-64368-a

Building the Bridge of Schr\"odinger: A Continuous Entropic Optimal Transport Benchmark

Over the last several years, there has been a significant progress in developing neural solvers for the Schr\"odinger Bridge (SB) problem and applying them to generative modeling. This new research field is justifiably fruitful as it is interconnected with the practically well-performing diffusion models and theoretically-grounded entropic optimal transport (EOT). Still the area lacks non-trivial tests allowing a researcher to understand how well do the methods solve SB or its equivalent continuous EOT problem. We fill this gap and propose a novel way to create pairs of probability distributions for which the ground truth OT solution in known by the construction. Our methodology is generic and works for a wide range of OT formulations, in particular, it covers the EOT which is equivalent to SB (the main interest of our study). This development allows us to create continuous benchmark distributions with the known EOT and SB solution on high-dimensional spaces such as spaces of images. As an illustration, we use these benchmark pairs to test how well do existing neural EOT/SB solvers actually compute the EOT solution. The benchmark is available via the link: https://github.com/ngushchin/EntropicOTBenchmark

Dynamic Blockage in Indoor Reflection-Aided Sub-Terahertz Wireless Communications

The sixth-generation cellular systems are expected to utilize the text sub-terahertz frequency band covering 100–300-GHz. Due to high path losses, the coverage of such systems will be limited to a few tens of meters making them suitable for indoor environments. As compared to outdoor deployments, indoor usage of text sub-terahertz systems is characterized by the need to operate over shorter distances using both line-of-sight (LoS) and text in-reflection propagation paths. This potentially results not only in the attenuation of radio signal, but in the appearance of diffraction signatures in its text time-related metrics too. We conduct a detailed measurement campaign at the carrier frequency of 156 GHz and report on the dynamics of the reflection and blockage losses as well as signal fall, blockage, and recovery times over various in-reflection paths. We also develop reflection model and use it to extract the complex permittivities of glass, drywall and aerated concrete from their measured reflection spectra. The extracted permittivities of $7.23+0.22i$ , $2.63+0.026i$ , $1.9+0.017i$ are consistent with the text material-dependent reflection losses, which are as high as 16 dB for transverse electric (TE)-polarized and 39 dB for transverse magnetic (TM)-polarized signals. Moreover, the asymmetry in the side lobe levels of the transmitting and receiving antenna beams results in the additional losses ranging from 16 to 49 dB as measured for 3.55–4.3-m long text non-specular paths with the angles of departure and reception within $30-70^{\circ }$ . The blockage losses, in turn, are in the range of 6–17 dB. We observe that the presence of a text re-directing material does not affect their mean value. However, the acquired blockage duration, signal fall and recovery times are noticeably smaller than in the LoS channels with the same directivity. This implies that the text time-budget for blockage detection is much smaller: it reduces to just 20–40 ms as compared to 80–100 ms intrinsic to the LoS propagation paths

A Practical Perspective on 5G-Ready Highly Dynamic Spectrum Management with LSA

A diversity of wireless technologies will collaborate to support the fifth-generation (5G) communication networks with their demanding applications and services. Despite decisive progress in many enabling solutions, next-generation cellular deployments may still suffer from a glaring lack of bandwidth due to inefficient utilization of radio spectrum, which calls for immediate action. To this end, several capable frameworks have recently emerged to all help the mobile network operators (MNOs) leverage the abundant frequency bands that are utilized lightly by other incumbents. Along these lines, the recent Licensed Shared Access (LSA) regulatory framework allows for controlled sharing of spectrum between an incumbent and a licensee, such as the MNO, which coexist geographically. This powerful concept has been subject to several early technology demonstrations that confirm its implementation feasibility. However, the full potential of LSA-based spectrum management can only become available if it is empowered to operate dynamically and at high space-time-frequency granularity. Complementing the prior efforts, we in this work outline the functionality that is required by the LSA system to achieve the much needed flexible operation as well as report on the results of our respective live trial that employs a full-fledged commercial-grade cellular network deployment. Our practical results become instrumental to facilitate more dynamic bandwidth sharing and thus promise to advance on the degrees of spectrum utilization in future 5G systems without compromising the service quality of their users