Livre et rapports

Influence of Generated Defects by Ar Implantation on the Thermoelectric Properties of ScN
- Burcea Razvan
- Barbot Jean-François
- Renault Pierre-Olivier
- Eyidi Dominique
- Girardeau Thierry
- Marteau Marc
- Giovannelli Fabien
- Zenji Ahmad
- Rampnoux Jean-Michel
- Dilhaire Stefan
- Eklund Per
- Le Febvrier Arnaud
ACS Applied Energy Materials, ACS , 2022, 5 (9), pp.11025-11033 . Nowadays, making thermoelectric materials more efficient in energy conversion is still a challenge. In this work, to reduce the thermal conductivity and thus improve the overall thermoelectric performances, point and extended defects were generated in epitaxial 111-ScN thin films by implantation using argon ions. The films were investigated by structural, optical, electrical, and thermoelectric characterization methods. The results demonstrated that argon implantation leads to the formation of stable defects (up to 750 K operating temperature). These were identified as interstitial-type defect clusters and argon vacancy complexes. The insertion of these specific defects induces acceptor-type deep levels in the band gap, yielding a reduction in the free-carrier mobility. With a reduced electrical conductivity, the irradiated sample exhibited a higher Seebeck coefficient while maintaining the power factor of the film. The thermal conductivity is strongly reduced from 12 to 3 W·m–1·K–1 at 300 K, showing the influence of defects in increasing phonon scattering. Subsequent high-temperature annealing at 1573 K leads to the progressive evolution of these defects: the initial clusters of interstitials evolved to the benefit of smaller clusters and the formation of bubbles. Thus, the number of free carriers, the resistivity, and the Seebeck coefficient are almost restored but the mobility of the carriers remains low and a 30% drop in thermal conductivity is still effective (ktotal ∼ 8.5 W·m–1·K–1). This study shows that control defect engineering with defects introduced by irradiation using noble gases in a thermoelectric coating can be an attractive method to enhance the figure of merit of thermoelectric materials. (10.1021/acsaem.2c01672)
DOI : 10.1021/acsaem.2c01672
Profitability and Revenue Uncertainty of Wind Farms in Western Europe in Present and Future Climate
- Alonzo Bastien
- Concettini Silvia
- Creti Anna
- Drobinski Philippe
- Tankov Peter
Energies, MDPI , 2022, 15 (17), pp.6446 . Investments into wind power generation may be hampered by the uncertainty of future revenues caused by the natural variability of the wind resource, the impact of climate change on wind potential and future electricity prices, and the regulatory risks. We quantify the uncertainty of the economic value of wind farms in France, Germany, and Denmark, and evaluate the cost of support mechanisms needed to ensure the profitability of wind farms under present and future climates. To this end, we built a localised model for wind power output and a country-level model for electricity demand and prices. Our study reveals that support mechanisms are needed for current market conditions and the current climate, as well as under future climate conditions according to several scenarios for climate change and energy transition. The cost of support mechanisms during a 15-year period is evaluated to EUR 3.8 to EUR 11.5 billion per year in France, from EUR 15.5 to EUR 26.5 billion per year in Germany, and from EUR 1.2 to EUR 3.3 billion per year in Denmark, depending on the scenario considered and the level of penetration of wind energy. (10.3390/en15176446)
DOI : 10.3390/en15176446
ToF-SIMS Li Depth Profiling of Pure and Methylated Amorphous Silicon Electrodes After Their Partial Lithiation
- Feng Yue
- Koo Bon Min
- Seyeux Antoine
- Światowska Jolanta
- Henry de Villeneuve Catherine
- Rosso Michel
- Ozanam François
ACS Applied Materials & Interfaces, Washington, D.C. : American Chemical Society , 2022, 14 (31), pp.35716-35725 . Pure (a-Si:H) and methylated (a-Si0.95(CH3)0.05:H) amorphous silicon thin films were analyzed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) after partial lithiation. Depth profiling gives insight into the lithiation mechanism of the material enabling to study the detailed biphasic process in the first lithiation process. Lithiation induces swelling and roughening of the active layer. In both a-Si:H and a-Si0.95(CH3)0.05:H, no measurable Li diffusion was observed after stopping current-induced lithiation. After applying the same lithiation charges, distinct Li profiles were observed for these two materials. Unlike a-Si:H, the Li concentration drops slowly from the heavily lithiated region to the non-lithiated region in a-Si0.95(CH3)0.05:H. This apparent progressive transition between the lithiated and lithium-free regions is attributed to the presence of nanovoids inside the material. When their concentration is high enough, these nanovoids constitute favorable quasi-percolating paths for lithium during the first lithiation. A specific model was developed to simulate the Li depth profiles, fully supporting this hypothesis. (10.1021/acsami.2c08203)
DOI : 10.1021/acsami.2c08203
Altiratinib blocks Toxoplasma gondii and Plasmodium falciparum development by selectively targeting a spliceosome kinase
- Swale Christopher
- Bellini Valeria
- Bowler Matthew
- Flore Nardella
- Brenier-Pinchart Marie-Pierre
- Cannella Dominique
- Belmudes Lucid
- Mas Caroline
- Couté Yohann
- Laurent Fabrice
- Scherf Artur
- Bougdour Alexandre
- Hakimi Mohamed-Ali
Science Translational Medicine, American Association for the Advancement of Science (AAAS) , 2022, 14 (656), pp.17 p. . The Apicomplexa comprise a large phylum of single-celled, obligate intracellular protozoa that include Toxoplasma gondii , Plasmodium , and Cryptosporidium spp., which infect humans and animals and cause severe parasitic diseases. Available therapeutics against these diseases are limited by suboptimal efficacy and frequent side effects, as well as the emergence and spread of resistance. We use a drug repurposing strategy and identify altiratinib, a compound originally developed to treat glioblastoma, as a promising drug candidate with broad spectrum activity against apicomplexans. Altiratinib is parasiticidal and blocks the development of intracellular zoites in the nanomolar range and with a high selectivity index when used against T. gondii . We have identified Tg PRP4K of T. gondii as the primary target of altiratinib using genetic target deconvolution, which highlighted key residues within the kinase catalytic site that conferred drug resistance when mutated. We have further elucidated the molecular basis of the inhibitory mechanism and species selectivity of altiratinib for Tg PRP4K and for its Plasmodium falciparum counterpart, Pf CLK3. Our data identified structural features critical for binding of the other Pf CLK3 inhibitor, TCMDC-135051. Consistent with the splicing control activity of this kinase family, we have shown that altiratinib can cause global disruption of splicing, primarily through intron retention in both T. gondii and P. falciparum . Thus, our data establish parasitic PRP4K/CLK3 as a potential pan-apicomplexan target whose repertoire of inhibitors can be expanded by the addition of altiratinib. (10.1126/scitranslmed.abn3231)
DOI : 10.1126/scitranslmed.abn3231
Determining solar cell parameters and degradation rates from power production data
- Chakar Joseph
- Pavlov Marko
- Bonnassieux Yvan
- Badosa Jordi
Energy Conversion and Management: X, Elsevier , 2022, 15, pp.100270 . (10.1016/j.ecmx.2022.100270)
DOI : 10.1016/j.ecmx.2022.100270
Optimal Transport for Conditional Domain Matching and Label Shift
- Rakotomamonjy Alain
- Flamary Rémi
- Gasso Gilles
- Alaya M. El
- Berar Maxime
- Courty Nicolas
Machine Learning, Springer Verlag , 2022, 111 (5), pp.1651-1670 . We address the problem of unsupervised domain adaptation under the setting of generalized target shift (both class-conditional and label shifts occur). We show that in that setting, for good generalization, it is necessary to learn with similar source and target label distributions and to match the class-conditional probabilities. For this purpose, we propose an estimation of target label proportion by blending mixture estimation and optimal transport. This estimation comes with theoretical guarantees of correctness. Based on the estimation, we learn a model by minimizing a importance weighted loss and a Wasserstein distance between weighted marginals. We prove that this minimization allows to match class-conditionals given mild assumptions on their geometry. Our experimental results show that our method performs better on average than competitors accross a range domain adaptation problems including digits,VisDA and Office. Code for this paper is available at \url{https://github.com/arakotom/mars_domain_adaptation}. (10.1007/s10994-021-06088-2)
DOI : 10.1007/s10994-021-06088-2
A novel deep reinforcement approach for IIoT microgrid energy management systems
- Dridi Aicha
- Afifi Hossam
- Moungla Hassine
- Badosa Jordi
IEEE Transactions on Green Communications and Networking, IEEE , 2022, 6 (1), pp.148-159 . Introducing Deep Learning in the Industrial Internet of Things (IIoT) brings many benefits, such as network resilience and bandwidth usage reduction. In this work, we propose an innovative reinforcement learning architecture to implement distributed energy management systems for microgrids. The architecture is based on novel reinforcement learning and on time series prediction. The designed reinforcement learning uses classical recurrent neural networks instead of the habitual SAR (State Action Reward) method that most of the recent bibliography considers. We applied various techniques (Exact resolution, Rule-Based, Q-Learning, and our designed reinforcement learning) on a distributed IIoT energy control architecture. The proposed method has shown better results compared to the exact resolution and the Q-Learning algorithm. It results in fast learning systems with a small number of training samples. We identified and tested several management strategies. Integer Linear Programming (ILP) optimal expressions and strategy-based implementations are derived. We utilize the obtained results to train the recurrent neural network. Comparative results are very encouraging and prone to a generalization of our approach instead of the classical methods. (10.1109/TGCN.2021.3112043)
DOI : 10.1109/TGCN.2021.3112043
Generating natural adversarial Remote Sensing Images
- Burnel Jean-Christophe
- Fatras Kilian
- Flamary Rémi
- Courty Nicolas
IEEE Transactions on Geoscience and Remote Sensing, Institute of Electrical and Electronics Engineers , 2022, 60, pp.1-14 . Over the last years, Remote Sensing Images (RSI) analysis have started resorting to using deep neural networks to solve most of the commonly faced problems, such as detection, land cover classification or segmentation. As far as critical decision making can be based upon the results of RSI analysis, it is important to clearly identify and understand potential security threats occurring in those machine learning algorithms. Notably, it has recently been found that neural networks are particularly sensitive to carefully designed attacks, generally crafted given the full knowledge of the considered deep network. In this paper, we consider the more realistic but challenging case where one wants to generate such attacks in the case of a black-box neural network. In this case, only the prediction score of the network is accessible, given a specific input. Examples that lure away the network's prediction, while being perceptually similar to real images, are called natural or unrestricted adversarial examples. We present an original method to generate such examples, based on a variant of the Wasserstein Generative Adversarial Network. We demonstrate its effectiveness on natural adversarial hyper-spectral image generation and image modification for fooling a state-of-the-art detector. Among others, we also conduct a perceptual evaluation with human annotators to better assess the effectiveness of the proposed method. (10.1109/TGRS.2021.3110601)
DOI : 10.1109/TGRS.2021.3110601
Chiroptical properties of anionic and neutral nickel(II) bis(dithiolene) complexes based on methyl and dimethyl‐dddt ligands
- Abhervé Alexandre
- Mroweh Nabil
- Cauchy Thomas
- Pop Flavia
- Vanthuyne Nicolas
- Avarvari Narcis
Chirality, Wiley , 2022, 34, pp.4-12 . Racemic and enantiopure nickel(II) bis(dithiolene) anionic and neutral complexes based on the methyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (me-dddt) and dimethyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (dm-dddt) ligands have been experimentally and theoretically investigated with a special focus on their chiroptical properties. According to the TD DFT calculations the strong near infrared absorption bands typical for such complexes are only weakly active in CD and, moreover, they have opposite signs for the axial and equatorial conformations, due to the variation of the angle between the transition electric and magnetic dipole moments, thus leading to the mutual cancellation of their contributions and the absence of these bands in the experimental CD spectra. The influence of the number of stereogenic centres and of the oxidation state of the complexes on their chiroptical properties is highlighted. The solid state structure of the complex (TMA)[Ni(rac-me-dddt)2] (TMA = tetramethylammonium), determined by single crystal X-ray diffraction analysis, shows a rather unusual cis arrangement of the two dithiolene ligands, with the methyl substituents adopting an axial conformation, which is not the most stable one in the gas phase. (10.1002/chir.23375)
DOI : 10.1002/chir.23375
How Skillful Are the European Subseasonal Predictions of Wind Speed and Surface Temperature?
- Goutham Naveen
- Plougonven Riwal
- Omrani Hiba
- Parey Sylvie
- Tankov Peter
- Tantet Alexis
- Hitchcock Peter
- Drobinski Philippe
Monthly Weather Review, American Meteorological Society , 2022, 150, pp.1621-1637 . Subseasonal forecasts of 100-m wind speed and surface temperature, if skillful, can be beneficial to the energy sector as they can be used to plan asset availability and maintenance, assess risks of extreme events, and optimally trade power on the markets. In this study, we evaluate the skill of the European Centre for Medium-Range Weather Forecasts' subseasonal predictions of 100-m wind speed and 2-m temperature. To the authors' knowledge, this assessment is the first for the 100-m wind speed, which is an essential variable of practical importance to the energy sector. The assessment is carried out on both forecasts and reforecasts over European domain gridpoint wise and also by considering several spatially averaged domains, using several metrics to assess different attributes of forecast quality. We propose a novel way of synthesizing the continuous ranked probability skill score. The results show that the skill of the forecasts and reforecasts depends on the choice of the climate variable, the period of the year, and the geographical domain. Indeed, the predictions of temperature are better than those of wind speed, with enhanced skill found for both variables in the winter relative to other seasons. The results also indicate significant differences between the skill of forecasts and reforecasts, arising mainly due to the differing ensemble sizes. Overall, depending on the choice of the geographical domain and the forecast attribute, the results show skillful predictions beyond 2 weeks, and in certain cases, up to 6 weeks for both variables, thereby encouraging their implementation in operational decision-making. (10.1175/MWR-D-21-0207.1)
DOI : 10.1175/MWR-D-21-0207.1
Transcriptional regulation of photoprotection in dark-to-light transition—More than just a matter of excess light energy
- Redekop Petra
- Sanz-Luque Emanuel
- Yuan Yizhong
- Villain Gaelle
- Petroutsos Dimitris
- Grossman Arthur R
Science Advances, American Association for the Advancement of Science (AAAS) , 2022, 8 (22), pp.eabn1832 . In nature, photosynthetic organisms are exposed to different light spectra and intensities depending on the time of day and atmospheric and environmental conditions. When photosynthetic cells absorb excess light, they induce nonphotochemical quenching to avoid photodamage and trigger expression of “photoprotective” genes. In this work, we used the green alga Chlamydomonas reinhardtii to assess the impact of light intensity, light quality, photosynthetic electron transport, and carbon dioxide on induction of the photoprotective genes ( LHCSR1 , LHCSR3 , and PSBS ) during dark-to-light transitions. Induction (mRNA accumulation) occurred at very low light intensity and was independently modulated by blue and ultraviolet B radiation through specific photoreceptors; only LHCSR3 was strongly controlled by carbon dioxide levels through a putative enhancer function of CIA5, a transcription factor that controls genes of the carbon concentrating mechanism. We propose a model that integrates inputs of independent signaling pathways and how they may help the cells anticipate diel conditions and survive in a dynamic light environment. (10.1126/sciadv.abn1832)
DOI : 10.1126/sciadv.abn1832
Indazole versus indole-based cationic merocyanines with red shifted in-cellulo emission for selective mitochondria imaging
- Boujut Margot
- Chevalier Arnaud
- Schapman Damien
- Bénard Magalie
- Galas Ludovic
- Gallavardin Thibault
- Franck Xavier
Dyes and Pigments, Elsevier , 2022, 198, pp.109988 . Selective fluorophores are seminal for the development of fluorescent cell imaging allowing the simultaneous monitoring of several biological parameters. Mitochondria are one of the main targets of optical microscopy as their dynamics are related to many biological events. One of the best strategy to target them, is to design cationic dyes which accumulate preferentially in their membranes due to their high electrochemical potential. In this work, indazole scaffold was explored to build new cationic merocyanine dyes and compared with indole scaffold. This nitrogen heteroaromatic structure is still very uncommon in dyes chemistry; therefore, a lot has to be discovered about the effects of pH, solvent polarity and methylation in cyclic nitrogen on their optical properties. Finally, fluorescent imaging revealed that a red shift occurred in the emission of these molecules inside the mitochondria. (10.1016/j.dyepig.2021.109988)
DOI : 10.1016/j.dyepig.2021.109988
Cyclone generation Algorithm including a THERmodynamic module for Integrated National damage Assessment (CATHERINA 1.0) compatible with Coupled Model Intercomparison Project (CMIP) climate data
- Le Guenedal Théo
- Drobinski Philippe
- Tankov Peter
Geoscientific Model Development, European Geosciences Union , 2022, 15 (21), pp.8001-8039 . Tropical cyclones are responsible for a large share of global damage resulting from natural disasters, and estimating cyclone-related damage at a national level is a challenge attracting growing interest in the context of climate change. The global climate models, whose outputs are available from the Coupled Model Intercomparison Project (CMIP), do not resolve tropical cyclones. The Cyclone generation Algorithm including a THERmodynamic module for Integrated National damage Assessment (CATHERINA), presented in this paper, couples statistical and thermodynamic relationships to generate synthetic tracks sensitive to local climate conditions and estimates the damage induced by tropical cyclones at a national level. The framework is designed to be compatible with the data from CMIP models offering a reliable solution to resolve tropical cyclones in climate projections. We illustrate this by producing damage projections in representative concentration pathways (RCPs) at the global level and for individual countries. The algorithm contains a module to correct biases in climate models based on the distributions of the climate variables in the reanalyses. This model was primary developed to provide the economic and financial community with reliable signals allowing for a better quantification of physical risks in the long term, to estimate, for example, the impact on sovereign debt. (10.5194/gmd-15-8001-2022)
DOI : 10.5194/gmd-15-8001-2022
Molecular dynamics between amorphous and crystalline phases of e-beam irradiated piezoelectric PVDF thin films employing solid-state NMR spectroscopy
- Potrzebowska Natalia
- Cavani Olivier
- Kazmierski Slawomir
- Wegrowe Jean-Eric
- Potrzebowski Marek
- Clochard Marie-Claude
Polymer Degradation and Stability, Elsevier , 2022, 195, pp.109786 . Piezoelectric bi-axially and uni-axially stretched PVDF films subjected to e-beam irradiation doses of 5 kGy, 500 kGy and 1 MGy and films not irradiated have been studied. It was found that the piezoelectric responses of both untreated and e-beam irradiated PVDF films under strain strongly depends on their initial manufacturing processing. The initial structural differences were mainly based on crystalline phase composition, notably the α to β polymorph ratio. 19F MAS Solid State NMR measurements performed with fast sample spinning (31.25 kHz) allow us to accurately determine the proportion of crystal and amorphous phases. Considering only the crystalline phases, it was concluded that the uni-axial ((β)-PVDF) film was almost composed of 100% of β-phase while the biaxially-oriented ((α-β)-PVDF) was composed of 81% β-phase and 19% of α-phase. It was also shown that the changes of local dynamic processes of PVDF chains in kHz timescale enable to reflect the degradation of both the crystalline and amorphous phases. Presence of small molecular-weight chemical compounds was evidenced by Carr–Purcell–Meiboom–Gill (CPMG) 1H MAS NMR experiment. The degradation process was in agreement with melting peak decrease registered by DSC. 19F/1H T1ρ relaxation times and analysis of cross-polarization (CP) buildup curves are discussed. Significant scatter of relaxation parameters (19F T1ρ and 1H T1ρ) suggested an important degradation of polymer structure. The 1H T1ρ values for PVDF samples irradiated at 1 MGy mainly imply chain scission mechanisms of degradation rather than cross-linking processes. SS NMR spectroscopy data supported assumption that e-beam irradiation brings flexibility to piezoelectric PVDF films which improved their piezoelectric voltage output generated by deformation up to doses of 500kGy. Above this dose range, degradations were very important and affected severely PVDF films mechanical properties. (10.1016/j.polymdegradstab.2021.109786)
DOI : 10.1016/j.polymdegradstab.2021.109786
Upgrading agrifood co-products via solid fermentation yields environmental benefits under specific conditions only
- Javourez Ugo
- Rosero Delgado E.
- Hamelin L.
Nature Food, Nature , 2022, 3, pp.911–920 . Transforming residual biomass into edible ingredients is increasingly promoted to alleviate the environmental impacts of food systems. Yet, these approaches mostly rely on emerging technologies and constrained resources, and their environmental benefits remain unclear. By combining process-based consequential life cycle analysis, uncertainty assessment and biomass resource estimation, we quantified the impacts of deploying waste-to-nutrition pathways, here applied to the upgrading of agrifood co-products by solid-state fermentation (SSF). The benefits of reducing the demand for soybean meal by enhancing the protein concentration of feed through SSF do not compensate for the environmental burdens induced by the process on climate change, water depletion and land use. Besides unlocking feed markets to low-feed-quality streams, SSF outperforms energy valorization for most environmental impacts but is less competitive to mitigate climate change. Yet, SSF yields overall environmental benefits when unlocking food markets rather than supplying feed and energy services. Systematic methodological harmonization is required to assess the potential of novel ingredients, as outcomes vary according to the displaced food and feed baskets, and related land use changes. (10.1038/s43016-022-00621-9)
DOI : 10.1038/s43016-022-00621-9
Estimation of the Uncertainty due to Each Step of Simulating the Photovoltaic Conversion under Real Operating Conditions
- Migan-Dubois Anne
- Badosa Jordi
- Bourdin Vincent
- Torres Aguilar Moira
- Bonnassieux Yvan
International Journal of Photoenergy, Hindawi Publishing Corporation , 2021, 2021, pp.4228658 . The simulation of photovoltaic installations is a major issue for their sizing, their smart grid operation, and their fault detection and diagnosis. In this article, we study in detail every step of the simulation chain, either from the global horizontal irradiance and the ambient temperature (i.e., 4 steps of simulation) or considering the global in-plane irradiance and the module operating temperature (i.e., 1 step of simulation). The average quality estimation of the models is made through the calculations of average annual error between estimations and measurements, from 2016 to 2020. We have shown that the most uncertain step is the conversion of the global irradiance in its diffuse and direct components (17.2%, 2 models tested). If the model goes up to the in-plane irradiance, the average annual error decreases to 5.3% (6 models tested). The photovoltaic module temperature calculation induces an error of less than 2Â°C (4 models tested with 2 configurations). Meanwhile, the photoelectrical conversion shows a 3.5% error, similar to the measurement uncertainties, considering as input, the modules temperature, and the in-plane irradiance. If the simulation goes from the global irradiance and the ambient temperature measured locally, the estimation leads to a 6.7% average annual error. If the local measurements are not available, we can use the closest meteorological station’s records (13 for our study), and the error becomes 12.1%. Finally, we can also use the satellite images that lead to a 15.2% error, for average per year. The impact of available input shows that modeling the DC photovoltaic production, using global horizontal irradiance and ambient temperature, gives rise to an error of 6.6% for local measurements, 12.1% for weather station measurements, and 15.2% for satellite images estimations. This article thus draws up a review of the existing models, allowing to calculate the DC production of a photovoltaic module, depending on the atmospheric conditions, and highlights the most precise or most critical steps, considering in situ and weather station ground-based measurements, and also estimation from satellite images. (10.1155/2021/4228658)
DOI : 10.1155/2021/4228658
Electrochemical Active Surface Area Determination of Iridium‐Based Mixed Oxides by Mercury Underpotential Deposition
- Duran Silvia
- Elmaalouf Marine
- Odziomek Mateusz
- Piquemal Jean‐yves
- Faustini Marco
- Giraud Marion
- Peron Jennifer
- Tard Cédric
ChemElectroChem, Weinheim : Wiley-VCH , 2021, 8 (18), pp.3519-3524 . The electrochemical surface area (ECSA) is a critical property to describe, analyze and compare electrocatalysts. The determination of the mass activity of a given catalyst is associated with this parameter which can thus lead to materials benchmarking. Reliable and robust methods to measure ECSA are needed, and those have to accommodate different structures, morphologies and compositions. In this study, we investigate mercury underpotential deposition (HgUPD) as a way to estimate ECSA for ultraporous electrocatalysts based on iridium and iridium-molybdenum electrocatalysts for the oxygen evolution reaction. Results reveal a clear agreement between physisorption measurements and HgUPD with excellent reproducibility. The method shows also that pre- and post-catalysis surface area measurements are not affected by the catalytic process on short timescale, opening the possibility of electrocalyst stability and degradation monitoring. (10.1002/celc.202100649)
DOI : 10.1002/celc.202100649
Mixing nanostructured Ni/piezoPVDF composite thin films with e-beam irradiation: A beneficial synergy to piezoelectric response
- Potrzebowska Natalia
- Cavani Olivier
- Oral Ozlem
- Doaré Olivier
- Melilli Giuseppe
- Wegrowe Jean-Eric
- Clochard Marie-Claude.
Materials Today Communications, Elsevier , 2021, 28, pp.102528 . (10.1016/j.mtcomm.2021.102528)
DOI : 10.1016/j.mtcomm.2021.102528
Integration of climate variability and climate change in renewable energy planning
- Drobinski Philippe
- Tantet Alexis
Physics-Uspekhi, Turpion , 2021 . The trajectory outlined in the Paris Agreement to keep global warming below 2°C dictates not only the timing but also the speed at which the transformation of our energy system must take place to decarbonize energy production. Complying with the Paris Agreement requires reducing the carbon content of energy by about 75% and therefore making a rapid transition from fossil production to production based on low-carbon technologies. Among these technologies are those based on renewable energies. The variability of the climate itself induces a fluctuating or even an intermittent production of variable renewable energy (solar, wind, marine), challenging the balance of the electricity grid. In this context, to speak of energy transition is to face the problem of increasing the penetration of low-carbon energy production while limiting the variability while ensuring socio-technical feasibility and economic viability. The problem is not simple and the delicate balance between urgency (drastic reduction in emissions) and utopia (what strategy for low carbon energies, opportunities and obstacles) needs to be clearly defined. (10.3367/UFNe.2021.07.039080)
DOI : 10.3367/UFNe.2021.07.039080
Chiral Radical Cation Salts of Me-EDT-TTF and DM-EDT-TTF with Octahedral, Linear and Tetrahedral Monoanions
- Mroweh Nabil
- Bogdan Alexandra
- Pop Flavia
- Auban-Senzier Pascale
- Vanthuyne Nicolas
- Lopes Elsa B
- Almeida Manuel
- Avarvari Narcis
Magnetochemistry, MDPI , 2021, 7 (6), pp.87 . Methyl-ethylenedithio-tetrathiafulvalene (Me-EDT-TTF (1) and dimethyl-ethylenedithio-tetrathiafulvalene (DM-EDT-TTF (2) are valuable precursors for chiral molecular conductors, which are generally obtained by electrocrystallization in the presence of various counter-ions. The number of the stereogenic centers, their relative location on the molecule, the nature of the counter-ion and the electrocrystallization conditions play a paramount role in the crystal structures and conducting properties of the resulting materials. Here, we report the preparation and detailed structural characterization of the following series of radical cation salts: (i) mixed valence (1)2AsF6 as racemic, and (S) and (R) enantiomers; (ii) [(S)-1]AsF6·C4H8O and [(R)-1]AsF6·C4H8O where a strong dimerization of the donors is observed; (iii) (1)I3 and (2)I3 as racemic and enantiopure forms and (iv) [(meso)-2]PF6 and [(meso)-2]XO4 (X = Cl, Re), based on the new donor (meso)-2. In the latter, the two methyl substituents necessarily adopt axial and equatorial conformations, thus leading to a completely different packing of the donors when compared to the chiral form (S,S)/(R,R) of 2 in its radical cation salts. Single crystal resistivity measurements, complemented by thermoelectric power measurements in the case of (1)2AsF6, suggest quasi-metallic conductivity for the latter in the high temperature regime, with σRT ≈ 1–10 S cm–1, while semiconducting behavior is observed for the (meso)-2 based salts. (10.3390/magnetochemistry7060087)
DOI : 10.3390/magnetochemistry7060087
The Tuning Strategy of IPSL‐CM6A‐LR
- Mignot Juliette
- Hourdin Frédéric
- Deshayes Julie
- Boucher Olivier
- Gastineau Guillaume
- Musat Ionela
- Vancoppenolle Martin
- Servonnat Jérôme
- Caubel Arnaud
- Cheruy Frédérique
- Denvil Sebastien
- Dufresne Jean-Louis
- Éthé Christian
- Fairhead Laurent
- Foujols Marie-Alice
- Grandpeix Jean-Yves
- Levavasseur Guillaume
- Marti Olivier
- Menary Matthew B
- Rio Catherine
- rousset clement
- Silvy Yona
Journal of Advances in Modeling Earth Systems, American Geophysical Union , 2021, 13 (5), pp.e2020MS002340 . Climate change is a serious issue for humanity with important ramifications for policy and decision making. Robust and cost-efficient policies on mitigation and adaptation require assessments of current and future risks for natural and human systems under a range of socioeconomic scenarios. Those assessments rely on numerical simulations performed with state-of-the-art climate models. Simulations are coordinated at an international level within the Coupled Model Intercomparison Project (CMIP) which provides the bedrock for a substantial part of the publications synthesized in the Intergovernmental Panel on Climate Change (IPCC) reports. Such projects are fundamental in order to document the robust features as well as the relatively large uncertainties in the future climate projections. Among others, these uncertainties come from the various assumptions made by the ∼30 teams that develop CMIP-class models. In particular, because of (10.1029/2020ms002340)
DOI : 10.1029/2020ms002340
Charge-Transfer Chemical Reactions in Nanofluidic Fabry-Pérot Cavities
- Mauro L
- Caicedo K
- Jonusauskas G
- Avriller Rémi
Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society , 2021 . We investigate the chemical reactivity of molecular populations confined inside a nanofluidic Fabry-Pérot cavity. Due to strong light-matter interactions developing between a resonant electromagnetic cavity-mode and the electric dipole moment of the confined molecules, a polariton is formed. The former gets dressed by environmental vibrational and rotational degrees of freedom of the solvent. We call the resulting polariton dressed by its cloud of environmental excitation a "reacton", since it further undergoes chemical reactions. We characterize how the reacton formation modifies the kinetics of a photoisomerization chemical reaction involving an elementary charge-transfer process. We show that the reaction driving-force and reorganization energy are both modulated optically by the reactant concentration, the vacuum Rabi splitting and the de-tuning between the Fabry-Pérot cavity frequency and targeted electronic transition. Finally, we compute the ultrafast picosecond dynamics of the whole photochemical reaction. We predict that despite optical cavity losses and solvent-mediated non-radiative relaxation, measurable signatures of the reacton formation can be found in state-of-the-art pump-probe experiments. (10.1103/PhysRevB.103.165412)
DOI : 10.1103/PhysRevB.103.165412
POT : Python Optimal Transport
- Flamary Rémi
- Courty Nicolas
- Gramfort Alexandre
- Alaya Mokhtar Zahdi
- Boisbunon Aurélie
- Chambon Stanislas
- Chapel Laetitia
- Corenflos Adrien
- Fatras Kilian
- Fournier Nemo
- Gautheron Léo
- Gayraud Nathalie T H
- Janati Hicham
- Rakotomamonjy Alain
- Redko Ievgen
- Rolet Antoine
- Schutz Antony
- Seguy Vivien
- Sutherland Danica J
- Tavenard Romain
- Tong Alexander
- Vayer Titouan
Journal of Machine Learning Research, Microtome Publishing , 2021 . Optimal transport has recently been reintroduced to the machine learning community thanks in part to novel efficient optimization procedures allowing for medium to large scale applications. We propose a Python toolbox that implements several key optimal transport ideas for the machine learning community. The toolbox contains implementations of a number of founding works of OT for machine learning such as Sinkhorn algorithm and Wasserstein barycenters, but also provides generic solvers that can be used for conducting novel fundamental research. This toolbox, named POT for Python Optimal Transport, is open source with an MIT license.
Utility-Scale PV-Battery versus CSP-Thermal Storage in Morocco: Storage and Cost Effect under Penetration Scenarios
- Bouramdane Ayat-Allah
- Tantet Alexis
- Drobinski Philippe
Energies, MDPI , 2021, 14 (15), pp.4675 . In this study, we examine how Battery Storage (BES) and Thermal Storage (TES) combined with solar Photovoltaic (PV) and Concentrated Solar Power (CSP) technologies with an increased storage duration and rental cost together with diversification would influence the Moroccan mix and to what extent the variability (i.e., adequacy risk) can be reduced; this is done using recent (2013) cost data and under various penetration scenarios. To do this, we use MERRA-2 climate reanalysis to simulate hourly demand and capacity factors (CFs) of wind, solar PV and CSP without and with increasing storage capabilities—as defined by the CSP Solar Multiple (SM) and PV Inverter Loading Ratio (ILR). We adjust these time series to observations for the four Moroccan electrical zones over the year 2018. Our objective is to maximize the renewable (RE) penetration and minimize the imbalances between RE production and consumption considering three optimization strategies. We analyze mixes along Pareto fronts using the Mean-Variance Portfolio approach—implemented in the E4CLIM model—in which we add a maximum-cost constraint to take into account the different rental costs of wind, PV and CSP. We propose a method to calculate the rental cost of storage and production technologies taking into account the constraints on storage associated with the increase of SM and ILR in the added PV-BES and CSP-TES modules, keeping the mean solar CFs fixed. We perform some load bands-reduction diagnostics to assess the reliability benefits provided by each RE technology. We find that, at low penetrations, the maximum-cost budget is not reached because a small capacity is needed. The higher the ILR for PV, the larger the share of PV in the mix compared to wind and CSP without storage is removed completely. Between PV-BES and CSP-TES, the latter is preferred as it has larger storage capacity and thus stronger impact in reducing the adequacy risk. As additional BES are installed, more than TES, PV-BES is favored. At high penetrations, optimal mixes are impacted by cost, the more so as CSP (resp., PV) with high SM (resp., ILR) are installed. Wind is preferably installed due to its high mean CF compared to cost, followed by either PV-BES or CSP/CSP-TES. Scenarios without or with medium storage capacity favor CSP/CSP-TES, while high storage duration scenarios are dominated by low-cost PV-BES. However, scenarios ignoring the storage cost and constraints provide more weight to PV-BES whatever the penetration level. We also show that significant reduction of RE variability can only be achieved through geographical diversification. Technological complementarity may only help to reduce the variance when PV and CSP are both installed without or with a small amount of storage. However, the diversification effect is slightly smaller when the SM and ILR are increased and the covariances are reduced as well since mixes become less diversified. (10.3390/en14154675)
DOI : 10.3390/en14154675
A Minimal System Cost Minimization Model for Variable Renewable Energy Integration: Application to France and Comparison to Mean-Variance Analysis
- Tantet Alexis
- Drobinski Philippe
Energies, MDPI , 2021, 14 (16), pp.5143 . The viability of Variable Renewable Energy (VRE)-investment strategies depends on the response of dispatchable producers to satisfy the net load. We lack a simple research tool with sufficient complexity to represent major phenomena associated with the response of dispatchable producers to the integration of high shares of VRE and their impact on system costs. We develop a minimization of the system cost allowing one to quantify and decompose the system value of VRE depending on an aggregate dispatchable production. Defining the variable cost of the dispatchable generation as quadratic with a coefficient depending on macroeconomic factors such as the cost of greenhouse gas emissions leads to the simplest version of the model. In the absence of curtailment, and for particular parameter values, this version is equivalent to a mean-variance problem. We apply this model to France with solar and wind capacities distributed over the administrative regions of metropolitan France. In this case, ignoring the wholesale price effect and variability has a relatively small impact on optimal investments, but leads to largely underestimating the system total cost and overestimating the system marginal cost. (10.3390/en14165143)
DOI : 10.3390/en14165143