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Nowadays, smart meters are deployed in millions of residential households to gain significant insights from fine-grained electricity consumption data. The information extracted from smart meter data enables utilities to identify the socio-demographic characteristics of electricity consumers and then offer them diversified services. Traditionally, this task is implemented in a centralized manner with the assumption that utilities have access to all the smart meter data. However, smart meter data are measured and owned by different retailers in the retail market who may not be willing to share their data. To this end, a distributed electricity consumer characteristics identification method is proposed based on federated learning, which can preserve the privacy of retailers. Specifically, privacy-perseverance principal component analysis (PCA) is exploited to extract features from smart meter data. On this basis, an artificial neural network is trained in a federated manner with three weighted averaging strategies to bridge between smart meter data and the socio-demographic characteristics of consumers. Case studies on the Irish Commission for Energy Regulation (CER) dataset verify that the proposed federated method has comparable performance with the centralized model on both balanced and unbalanced datasets.

Semantic metadata standards pave the way for interoperability by providing building operators and application developers with common schemes to describe building resources. Applications can query building metadata models to retrieve the set of entities and relationships they need to operate, instead of hard-coding references to specific points and objects from the underlying data sources. Currently, querying such models requires the developer to be very specific when formulating queries in order to obtain meaningful answers (or any answer). The developer is inevitably expected to be familiar with the systems and components of the buildings being queried, as well as the schema used to represent them. The variety of buildings - both in the composition of their subsystems and in how they happen to be modeled - means that the developer will need to use multiple queries in order to retrieve necessary results. This is complex, time-consuming and error-prone. To address this limitation, we investigate query relaxation as a technique to facilitate discovery of meaningful building resources in a collection of ontology-based buildings data. We evaluate our query relaxation approach over a set of Brick models and demonstrate its use in the context of real-world building applications., BuildSys '21: Proceedings of the 8th ACM International Conference on Systems for Energy-Efficient Buildings, Cities, and Transportation, ISBN:978-1-4503-9114-6

The experimental advances in the study of electron impact double ionization using double coincidence e,(3-1)e or triple coincidence (e,3e) techniques are reviewed. The recent advent and extension of multianalysis and multidetection systems have allowed a second generation of (e,3e) spectrometers to be born. Their most pertinent characteristics are described. Illustrative results from both e,(3-1)e and (e,3e) experiments are discussed, showing all the promising potential of these highly differential studies for the detailed investigation of the fundamentals of the double ionization process.

Recent measurements of the (e, 3-1e) fourfold differential cross sections for the double ionization of helium are here extended to more complex targets, namely neon, argon and molecular nitrogen. The previous observations of large angular shifts in the experimental fourfold differential cross section (4DCS) distributions with respect to the momentum transfer axis and the existence of structures in these distributions are found to similarly hold here. For the three investigated targets, the experimental data are compared with the kinematical analysis previously given to describe the second-order, 'two-step 2' (TS2) double ionization (DI) mechanism. Such a comparison confirms our interpretation which allows the observed shifts and structures in the intensity distributions to be mostly related to the 'two-step 2' mechanism, which is shown to predominate over the first-order 'shake-off' (SO) and 'two-step 1' (TS1) mechanisms under the present kinematics. The experimental data are also compared to the predictions of a first Born and second Born model, showing rather mixed agreement.

International audience; The (e, 3-1e) four-fold differential cross sections (4DCS) are measured for the double ionization of helium in coplanar asymmetric geometry for a wide range of ejected electron energies and at an incident energy of about 600 eV. The experimental angular distributions of the 4DCS are characterized by large angular shifts of the forward and backward lobes with respect to the momentum transfer direction or its opposite, respectively. This validates our previously published results [ Lahmam-Bennani et al 2002 J. Phys. B: At. Mol. Opt. Phys. 35 L59 ] which were questioned by Götz et al [ 2003 J. Phys. B: At. Mol. Opt. Phys. 36 L77 ]. A qualitative, kinematical analysis is given which allows relating these shifts and the observed structures in the intensity distributions to the second order, 'two-step 2 ' double ionization mechanism, which is shown to predominate over the first-order 'shake-off ' and 'two-step 1 ' mechanisms under the present kinematics.

A version of the J-matrix method for solving numerically the three-body Faddeev-Merkuriev differential equations is proposed. This version allows one to take into account the full spectrum of the two-body Coulomb subsystem. As a result, a discrete analog of the Lippmann-Schwinger equation is obtained which allows one to interpret correctly the three-body wave function in two-body domains. The scheme is applied to calculations of the fully resolved absolute differential cross sections for the He(e,2e)He{sup +} reactions leaving the residual ion in an excited state, at small energy and momentum transfer. The results are in good agreement with the experiment both in shape and in absolute value.

Experimental results obtained with our multi parameter multi-coincidence spectrometer are presented for the (e,3e) double ionisation of Ar and (e,2e) single ionisation of small molecules. The (e,3e) measurements are discussed in terms of competition between the two double ionisation processes present under the chosen kinematics, and qualitative conclusions are given. The results for the ionisation of H2 and the outer orbital of N2 are compared with the predictions of the most elaborate available theoretical models for description of the molecular ionisation process. Overall reasonable agreement is observed and tentative interpretations for the discrepancies are discussed.

A multicoincidence electron–electron spectrometer has been modified by including two ion detectors in order to enable both photoelectron–Auger electron and photoelectron (or Auger electron)-ion coincidence measurements as a substantial step towards a complete experiment. Results of the first use of this set-up to study the photoelectron–Auger electron angular correlations and photoelectron angular distributions of “fixed-in-space” molecules in the case of the C 1s ionization of the CO molecule are presented and compared with theoretical calculations in the Hartree–Fock approximation based on the two-step model.

The second order, Two-Step-2 (TS2) mechanism for electron impact double ionization (DI) of various targets at intermediate incident energy is investigated based on a kinematical analysis which assumes the DI to result from two successive (e,2e) single ionization (SI) events. The results show that under the present kinematics, the inclusion of the recoil scattering in each of these (e,2e)-SI steps (in previous studies only the binary scattering was considered) allows a more detailed understanding of the various peaks observed in the experimental angular distributions of the ejected electrons in both (e,3-1e) and (e,3e) experiments.

International audience; Our recent measurements [ Lahmam-Bennani et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 105201 ] of the (e, 3-1e) four-fold differential cross sections (4DCS) for double ionisation of helium are here extended to a wider range of ejected electron energies and very asymmetric energy sharing. The previous observations of large angular shifts in the experimental 4DCS distributions with respect to the momentum transfer axis are once again reproduced by the new measured data. Moreover, comparison of all the data sets with the kinematical analysis previously given and with two newly developed non-first order theoretical models for double ionisation, namely 'the two-step2 - Monte Carlo Event Generator (TS2-MCEG) and a second Born approximation (B2) confirms our interpretation which allows relating the observed shifts and the existence of structures in the intensity distributions mostly to the second order, 'two-step 2 ' (TS2) double ionisation mechanism, which is shown to predominate over the first-order 'shake-off ' (SO) and 'two-step 1 ' (TS1) mechanisms under the present kinematics. 3

In this brief review, we illustrate the potentialities and the power of electron-electron coincidence studies to investigate the dynamics of single ionization SI [(e,2e) case] or double ionization DI [(e,3e) case] processes. An example for (e,2e) SI of rare gas atoms is presented with a new insight into the behaviour of the recoil versus the binary intensity. A second example for (e,2e) SI of molecules is used to illustrate the observation of a purely molecular effect, namely the signature of interference effects due to the two-center nature of the H2 molecule. The third example discusses an unprecedented triple coincidence study involving the scattered – ejected – Auger electrons emitted from an argon target. It is shown that the method allows to disentangle the contribution of various DI mechanisms.

We analyze the recoil-to-binary peak ratio in an energetic (e,2e) reaction on the valence ns sub-shell of noble gas atoms. Dramatic qualitative change in this ratio dependence on the ejected electron energy can be explained by variation of reflectivity of the short-range Hartree-Fock potential. The reflectivity increases profoundly from lighter (He) to heavier (Ne and Ar) noble gas atoms because of modification of the scattering phases due to occupation of the target p orbitals (Levinson theorem). This effect is further modified due to strong inter-shell correlations in Ar. These theoretical predictions are confirmed experimentally.

We report new coplanar (e,2e) measurements characterised by large energy transfer and close to minimum momentum transfer from the projectile to the target. Ionisation of the two-electron targets He and H2 is investigated under these particular kinematics. The experimental data are compared with the predictions of the most elaborate theoretical models. The obtained good agreement motivated us to extend our research to the case of more complex targets such as Ar. Comparison with the most elaborate models in the case of multi-electron targets is excellent. Destructive and constructive interference effects in the case of H2 are observed and discussed.

A new version of the J-matrix method is formulated for describing the (e; 2e) and (e; 3e) scattering of a fast projectile electron on a helium atom. The derived three-body final state wave function exactly satisfies two-body boundary conditions when one ejected electron is at large distances from while the other is close to the nucleus. The obtained results for differential cross sections of the He(e; 2e)He+ and He(e; 3e)He++ reactions are in a good agreement with experiment both in shape and absolute value.

International audience

We report new coplanar (e, 2e) results for ionization of the He 1s and Ne 2p and 2s subshells under kinematics which have remained rather unexplored to date and characterized by large energy transfer and close to minimum momentum transfer from the projectile to the target. The experimental results obtained in two laboratories are used as a sensitive test of a number of state-of-the-art available theoretical models for multi-electron atoms. The He results are in excellent agreement with convergent close-coupling predictions as well as with distorted-wave + Gamow and hybrid distorted-wave + R-matrix models. In the Ne case, an overall satisfactory agreement with experiments is obtained for all considered models. The importance of post-collisional interaction effects is demonstrated whereas second-order effects in the projectile-target interaction at small distances are shown to be negligibly small. Remaining discrepancies between theories and experiments are discussed.

The (e, 2e) technique has been applied successfully to valence shell ionisation of many targets, but studies of inner shell ionisation by this technique have been limited. The triple difierential cross section for the latter process exhibits behaviour which is very difierent to that observed for valence shell ionisation, particularly when the energy of the slow ejected electron is decreased below the binding energy of the inner shell orbital. Our recent results for inner shell ionisation of argon and krypton will be discussed, and comparisons made with distorted wave calculations. The importance and utility of the (e, 2e) technique in investigating electron impact ionisation may be gauged from the range of target species and kinematical conditions over which measurements have been performed. The primary theme of this workshop is the application of the (e, 2e) technique in electron momentum spectroscopy (EMS), where structural information about the electron motion in the target may be obtained. However, another emphasis in the application of the (e, 2e) technique is in studies of the dynamics of the ionisation process itself. Aspects of the collision such as distortions in the incident and outgoing channels, the in∞uence of multiple scattering, decay processes following the ionisation and electron{electron correlation efiects such as post collision interaction have been studied. Valence shell ionisation of numerous atomic targets has been studied in considerable detail, with most attention being directed to simple targets such as helium and hydrogen, where the target wavefunctions are well known. For other atoms, uncertainties in the target description can complicate the theoretical description of the collision; nevertheless good progress has been made in the theoretical approaches to this problem. For larger atoms, core ionisation becomes a possibility. Associated with the primary core-hole formation is the possibility of Auger emission. Indeed, for targets other than very heavy atoms, the Auger decay process dominates over photon decay. The process may be represented as follows

L'étude expérimentale antérieure (J. Phys. E 8 (1975) 909) des caractéristiques du jet moléculaire formé par une buse multicanal est reprise et complétée ici par des résultats nouveaux. Dans le domaine de pression d'admission considéré, nous montrons que l'écoulement du gaz ne se fait pas dans un régime moléculaire mais est du type visqueux. Des mesures précises du diamètre angulaire du jet sont présentées, et un accord assez satisfaisant est obtenu avec les calculs de Troitskii. Grâce à une plus grande finesse d'analyse, une conclusion erronée de l'étude précédente est corrigée ici : aucune condensation dans le jet n'est observée jusqu'à des pressions d'admission de 4 bars, permettant ainsi d'obtenir des cibles purement constituées de molécules libres, et dont la densité sur l'axe du jet, à environ 0,5 mm de la buse, excède 1019 molécules/cm3.

The symmetrical part of the neon Compton profile, obtained by 25 keV electron scattering is compared to impulse approximation calculations, and the antisymmetrical part is compared to a qualitative estimate by Tavard for hydrogenic orbitals. Previous results on NH3 are recalled and a physical interpretation is attempted.

The double ionization of He by electron impact at 580 eV has been studied in a coplanar symmetric (e,(3–1)e) experiment, in which two fast electrons of 250 eV are detected. In this way a momentum transfer as large as 6 a.u. is achieved. The results are compared with the predictions of a theoretical model based on the impulse (knock-out) approximation. The calculations, which include radial correlation of electrons in the He ground state wave function, better describe the experiment than those with an uncorrelated wave function.