arXiv subjects

Hervé Bercegol

Publications and source records attributed to Hervé Bercegol.

7 recordsLinked to original sources

arXiv2026

Energy-Optimal Allocation of Storage in Transmission Grid Networks

The deployment of renewable energy technologies supposes the connection to the power grid of many new, distributed, and variable electricity production facilities. Among the investments deeply needed for a successful shift to clean energy, electricity storage systems are key to provide power reliably, continuously and economically. Here, we are concerned with the energy that must be invested and embodied in storage devices and in production oversizing to cope with natural variations of renewable electricity production, and compensate for any gap between production and consumption. We developed a model to analyze the variation of energy expenses with the location in the grid, capacity of storage and production oversizing. We apply it to a time scale of fluctuations of a few hours that can be taken care of by Li-ion batteries to calculate the optimal storage capacity and production oversizing yielding a maximum value of the ESOI ratio [Energy Stored On energy Invested] at a given satisfaction rate of customer demand. We evaluate these values for a rescaled present-time French power mix and two idealized zero-emission mixes (100% PV and 100% wind). In parallel, using a recently developed model of French transmission grid, a centrality-based analysis shows that locating storage at nodes of maximal installed power minimizes additional Joule losses. These results generalize existing grid-level energy return frameworks to incorporate storage sizing, placement, and transmission losses into a unified assessment of future power grid configurations.

physics.soc-ph↗

arXiv2026

Rotational Quantum Friction via Spontaneous Decay

A fascinating effect belonging to the field of vacuum forces and fluctuations is that of quantum friction. It refers to the prediction of a dissipative force acting on a moving object due to the quantum vacuum field. In this work, we investigate rotational quantum friction where a diatomic polar molecule rotates around its own center of mass in free space. We quantize the rotational motion and investigate the resulting dissipation due to spontaneous decay. We find in the Markovian regime that a friction torque $\propto Ω^3$ persists even for zero temperature, and in agreement with the classical result in the limit of large rotational quantum number $l$. Within the non-Markovian short-time regime we find a friction $\proptoΩ$.

quant-ph↗

arXiv2025

Vacuum electromagnetic field correlations between two moving points

A renewed experimental interest in quantum vacuum fluctuations brings back the need to extend the study of electromagnetic vacuum correlations. Quantum or semi-classical models developed to understand various configurations should combine the effects of the zero-point fluctuations with those of blackbody radiation. In this paper, after a brief historical introduction and a rapid study of the electric field correlations in time domain, we propose exact and approximate expressions for the vacuum field correlations in Fourier space seen by moving points. We first present an exact computation of the electric field correlations, expressed in frequency space, between two points moving with opposite constant velocities on parallel trajectories. We also consider the electric field self-correlations, i.e. on the same moving point but at different frequencies, and comment the results related to special relativity. Then, we compute the exact main symmetrized quadratic electromagnetic field correlations between two points diametrically opposed on the same circular trajectory, with diameter r, covered at constant angular velocity Ω. We derive the expressions for the electromagnetic field correlations with itself and with its spatial derivatives, still at the locations of the moving points. Since the points we consider are accelerating, both the zero-point fluctuations and the blackbody spectrum give non-trivial results, for two-point correlations as well as for self-correlations. In both cases, results are shown at any vacuum temperature. For practical uses, we provide the first-order approximations in the small parameter Ωr/c with c being the speed of light.

quant-ph↗

arXiv2024

Metrics matter, a Formal comment on Ward et al Plos-One 2016 paper : Is decoupling GDP growth from environmental impact possible?

The Ward et al. (2016) Plos-One paper is an important, heavily-cited paper in the decoupling literature. The authors present evidence of 1990-2015 growth in material and energy consumption and GDP at a world level, and for selected countries. They find only relative decoupling has occurred, leading to their central claim that future absolute decoupling is implausible. However, the authors have made two key errors in their collected data: GDP data is in current prices which includes inflation, and their global material use data is the total mass of fossil energy materials. Strictly, GDP data should be in constant prices to allow for its comparison over time, and material inputs to an economy should be the sum of mineral raw materials. Amending for these errors, we find much smaller levels of energy-GDP relative decoupling, and no materials-GDP decoupling at all at a global level. We check these new results by adding data for 1900-1990 to provide a longer time series, and find consistently low (and even no) levels of global relative decoupling of material use. The central claim for materials over the implausibility of future absolute decoupling therefore not only remains valid but is reinforced by the corrected datasets.

econ.GN↗

arXiv2018

Mean-field approach for frequency synchronization in complex networks of two oscillator types

Oscillator networks with an asymmetric bipolar distribution of natural frequencies are useful representations of power grids. We propose a mean-field model that captures the onset, form and linear stability of frequency synchronization in such oscillator networks. The model takes into account a broad class of heterogeneous connection structures and identifies a functional form as well as basic properties that synchronized regimes possess classwide. The framework also captures synchronized regimes with large phase differences that commonly appear just above the critical threshold. Additionally, the accuracy of mean-field assumptions can be gauged internally through two model quantities. With our framework, the impact of local grid structure on frequency synchronization can be systematically explored.

nlin.AO↗

arXiv2018

Susceptibility of power grids to input fluctuations

With the increasing inclusion of regenerative resources in the energy mix, their intermittent character challenges power grid stability. Hence it is essential to determine which input fluctuations power grids are particularly vulnerable to. Focusing on angular stability in transmission grids, we propose a linear-response approach that yields a frequency-resolved measure of a grid's susceptibility to temporal input fluctuations. This approach can be applied to arbitrary transmission grid topologies as well as other settings described by oscillator networks.

nlin.AO↗

arXiv2015

Vacuum friction on a rotating pair of atoms

Zero-point quantum fluctuations of the electromagnetic vacuum create the widely known London-van der Waals attractive force between two atoms. Recently, there was a revived interest in the interaction of rotating matter with the quantum vacuum. Here, we consider a rotating pair of atoms maintained by London van der Waals forces and calculate the frictional torque they experience due to zero-point radiation. Using a semi-classical framework derived from the Fluctuation Dissipation Theorem, we take into account the full electrostatic coupling between induced dipoles. Considering the case of zero temperature only, we find a braking torque proportional to the angular velocity and to the third power of the fine structure constant. Although very small compared to London van der Waals attraction, the torque is strong enough to induce the formation of dimers in binary collisions. This new friction phenomenon at the atomic level should induce a paradigm change in the explanation of irreversibility.

cond-mat.mes-hall↗