Sunward-propagating Alfv\'enic fluctuations observed in the heliosphere

The mixture/interaction of anti-sunward-propagating Alfv\'enic fluctuations (AFs) and sunward-propagating Alfv\'enic fluctuations (SAFs) is believed to result in the decrease of the Alfv\'enicity of solar wind fluctuations with increasing heliocentric distance. However, SAFs are rarely observed at 1 au and solar wind AFs are found to be generally outward. Using the measurements from Voyager 2 and Wind, we perform a statistical survey of SAFs in the heliosphere inside 6 au. We first report two SAF events observed by Voyager 2. One is in the anti-sunward magnetic sector with a strong positive correlation between the fluctuations of magnetic field and solar wind velocity. The other one is in the sunward magnetic sector with a strong negative magnetic field-velocity correlation. Statistically, the percentage of SAFs increases gradually with heliocentric distance, from about 2.7% at 1.0 au to about 8.7% at 5.5 au. These results provide new clues for understanding the generation mechanism of SAFs

(11,13-Dimethyl-1,4,7,10-tetra­azacyclo­trideca-10,13-dienato)copper(II) per­chlorate

The title complex, [Cu(C11H21N4)]ClO4, comprises [CuII(L)]+ (L = 11,13-dimethyl-1,4,7,10-tetra­azacyclo­trideca-10,12-dien­ate) cations and a perchlorate anion. The Cu atom is located on a twofold crystallographic symmetry axis and is coordinated by four N atoms in a slightly distorted square-planar geometry. Inter­molecular N—H⋯O hydrogen bonds are present

Data-driven nonparametric Li-ion battery ageing model aiming at learning from real operation data - Part B : cycling operation

Conventional Li-ion battery ageing models, such as electrochemical, semi-empirical and empirical models, require a significant amount of time and experimental resources to provide accurate predictions under realistic operating conditions. At the same time, there is significant interest from industry in the introduction of new data collection telemetry technology. This implies the forthcoming availability of a significant amount of real-world battery operation data. In this context, the development of ageing models able to learn from in-field battery operation data is an interesting solution to mitigate the need for exhaustive laboratory testing. In a series of two papers, a data-driven ageing model is developed for Li-ion batteries under the Gaussian Process framework. A special emphasis is placed on illustrating the ability of the Gaussian Process model to learn from new data observations, providing more accurate and confident predictions, and extending the operating window of the model. The first paper of the series focussed on the systematic modelling and experimental verification of cell degradation through calendar ageing. Conversantly, this second paper addresses the same research challenge when the cell is electrically cycled. A specific covariance function is composed, tailored for use in a battery ageing application. Over an extensive dataset involving 124 cells tested during more than three years, different training possibilities are contemplated in order to quantify the minimal number of laboratory tests required for the design of an accurate ageing model. A model trained with only 26 tested cells achieves an overall mean-absolute-error of 1.04% in the capacity curve prediction, after being validated under a broad window of both dynamic and static cycling temperatures, Depth-of-Discharge, middle-SOC, charging and discharging C-rates

On spherical twisted conjugacy classes

Let G be a simple algebraic group over an algebraically closed field of good odd characteristic, and let theta be an automorphism of G arising from an involution of its Dynkin diagram. We show that the spherical theta-twisted conjugacy classes are precisely those intersecting only Bruhat cells corresponding to twisted involutions in the Weyl group. We show how the analogue of this statement fails in the triality case. We generalize to good odd characteristic J-H. Lu's dimension formula for spherical twisted conjugacy classes.Comment: proof of Lemma 6.4 polished. The journal version is available at http://www.springerlink.com/content/k573l88256753640

Mathematics Indicates That an HIV-Style Strategy Could Be Applied to Manage the Coronavirus

We have learned to live with many potentially deadly viruses for which there is no vaccine, no immunity, and no cure. We do not live in constant fear of these viruses, instead, we have learned how to outsmart them and reduce the harm they cause. A new mathematical model that combines the spread of diseases that do not confer immunity together with the evolution of human behaviors indicates that we may be able to fight new diseases with the same type of strategy we use to fight viruses like HIV.Comment: This article is available open access online here: https://link.springer.com/chapter/10.1007%2F16618_2020_2

Data-driven nonparametric Li-ion battery ageing model aiming at learning from real operation data – Part A : storage operation

Conventional Li-ion battery ageing models, such as electrochemical, semi-empirical and empirical models, require a significant amount of time and experimental resources to provide accurate predictions under realistic operating conditions. At the same time, there is significant interest from industry in the introduction of new data collection telemetry technology. This implies the forthcoming availability of a significant amount of real-world battery operation data. In this context, the development of ageing models able to learn from in-field battery operation data is an interesting solution to mitigate the need for exhaustive laboratory testing

PLASMA HEATING INSIDE INTERPLANETARY CORONAL MASS EJECTIONS BY ALFVÉNIC FLUCTUATIONS DISSIPATION

Nonlinear cascade of low-frequency Alfvénic fluctuations (AFs) is regarded as one of the candidate energy sources that heat plasma during the non-adiabatic expansion of interplanetary coronal mass ejections (ICMEs). However, AFs inside ICMEs were seldom reported in the literature. In this study, we investigate AFs inside ICMEs using observations from Voyager 2 between 1 and 6 au. It has been found that AFs with a high degree of Alfvénicity frequently occurred inside ICMEs for almost all of the identified ICMEs (30 out of 33 ICMEs) and for 12.6% of the ICME time interval. As ICMEs expand and move outward, the percentage of AF duration decays linearly in general. The occurrence rate of AFs inside ICMEs is much less than that in ambient solar wind, especially within 4.75 au. AFs inside ICMEs are more frequently presented in the center and at the boundaries of ICMEs. In addition, the proton temperature inside ICME has a similar "W"-shaped distribution. These findings suggest significant contribution of AFs on local plasma heating inside ICMEs