Université Paris-Saclay
Recent publications
This works concerns the study of well-balanced Lagrange-projection schemes applied to the two-layer shallow water system. In particular, a formulation of the mathematical model in Lagrangian coordinates is proposed. The HLL method is then applied to a simplified version of the resulting Lagrangian system. Furthermore, based on the acoustic-transport splitting interpretation, another approximate Riemann solver for the acoustic-Lagrangian step is described. Both an explicit and an implicit-explicit method are proposed, where the latter can allow very fast simulations in sub-critical regimes. Finally, we show numerical simulations in which the outputs are compared with the IFCP method’s results.
The use of a reference state, i.e. a baseline, for data analysis in guided wave based structural health monitoring is limiting the range of applicability of such approaches. This has been largely demonstrated in the literature in the presence of temperature changes but is also true in the presence of other varying environmental and operational conditions, as well as aging effects. This paper presents a novel self-referenced methodology, which is built to be intrinsically robust to the influence of external effects, allegedly including the ones not identified during system design. The method relies on the concept of instantaneous baseline, i.e. the comparison of multiple measurements acquired on structures with a high degree of similarity from a guided wave perspective. The subtlety of the approach is the detection of flaws of small influence on the measurements in the presence of extrinsic and intrinsic variabilities of comparatively larger influence over several similar samples. The method also includes a dimension reduction through the extraction of quantities of interest from the acquired signals, potentially enabling the analysis of several samples with limited data volume. The proposed method is successfully validated on 12 aluminum plates, each with a through-hole crack from 1 to 30mm in length in a laboratory environment with limited external parameters. Next, the approach is tested on 2 woven composite samples of complex shape with up to 7 similar paths from a guided wave perspective. The detection of an added mass is successful over the whole temperature range under consideration (−30°C to 30 °C) for all studied interrogating frequencies (50, 100, and 150 kHz). The proposed methodology performs significantly better than a state of the art imaging algorithm with temperature compensation applied to the same data.
This paper investigates a distributed fuzzy adaptive formation control for quadrotor multiple unmanned aerial vehicles under unmodeled dynamics and switching topologies. The unmanned aerial vehicles dynamics model is described by the Newton-Euler formula, and the actuator faults are considered in the system model in the form of multiplicative factors and additive factors. Due to the underactuated characteristics of the unmanned aerial vehicles, two objective attitude commands are generated by designing a virtual control signal, which are transmitted to the attitude subsystem, and then the position controller is solved. By constructing a distributed communication mechanism between unmanned aerial vehicles, an adaptive formation control strategy is proposed, which can enable unmanned aerial vehicles to update their position and speed online according to their neighbor information, and then achieve the required formation. In addition, a fuzzy adaptive sliding mode controller is designed to ensure that the tracking errors of unmanned aerial vehicles converge to the neighborhood of the origin. Finally, the simulation results verify the effectiveness of the proposed control strategy.
The deformation mechanisms were studied in metastable Zr-13.8Nb-0.7Hf and Zr-15.5Nb-0.7Hf (wt.%) alloys exhibiting complex microstructures due to quenched-in precipitates (acicular body-centered tetragonal phase and globular monoclinic phase) in beta grains. Twinning-induced plasticity (TWIP) effect was observed in Zr-13.8Nb-0.7Hf via {332}<113> twinning operation, resulting in higher strain-hardening rate and uniform elongation than those of Zr-15.5Nb-0.7Hf deforming via only dislocation glide. In-situ characterizations, by applying tensile deformation during electron backscattered diffraction (EBSD) mapping and transmission electron microscopy (TEM) observation, were conducted to clarify the twinning process and the role of quenched-in precipitates when interacting with deformation twins.
Pollen beetles (Brassicogethes spp.) and stem flea beetles (Psylliodes chrysocephala) are among the main pests of oilseed rape crops in Europe, causing high yield losses. Increasing insecticide resistance and environmental concerns have highlighted the need for alternatives to chemical control, such as conservation biological control. Conservation biological control can be enhanced by providing resources to beneficial organisms in and around crop fields. Flower strips are a promising tool to provide nectar resources for parasitoids. In addition, the planting of such resources in field margins should be reinforced by the absence of insecticide application. However, the presence and amount of weeds within the field could mitigate the effect of flower strips and needs to be explored. We surveyed 25 oilseed rape fields in 2019 and 2020. Ten of these fields were adjacent to a sown wildflower strip. We compared an eco-friendly strategy (wildflower strip without insecticide in spring) to a conventional approach (no wildflower strip and chemical control of pests). We assessed the parasitism of stem flea beetle and pollen beetle larvae in the spring, at distances of 5 m and 30 m from the wildflower strip or the natural field margin. We performed botanical surveys in wildflower strips and natural field margins and within the field, to assess the availability of accessible nectar resources to parasitoids. Stem flea beetle parasitism rates were not affected by the strategy used, but the eco-friendly strategy had a weak positive effect on pollen beetle parasitism. Unexpectedly, the amount of accessible nectar did not differ significantly between wildflower strips in the eco-friendly strategy and natural herbaceous field margins in the conventional strategy. The amount of accessible nectar provided by weeds in the field was positively related only to pollen beetle parasitism rates. By contrast, the amount of accessible nectar for both spontaneous field margin and flower strips had no effect on the rates of parasitism of either species. Parasitism rate decreased significantly with decreasing distance to the field edge, for both species. Our results suggest that further studies are required: (i) to improve the composition of wildflower strips, so as to provide more accessible nectar resources at the start of spring and (ii) to explore more management strategy options, notably on in-field resources management such as unsown patches or intercropping.
Ammonia (NH 3) emissions are an important pathway of nitrogen (N) losses in rice paddies. Lime application and straw retention are common practices to enhance soil fertility in acidic soils. However, the interaction of lime and straw application on NH 3 emissions from paddies remain unclear. Here, a factorial experiment was employed to examine the interactive effects of slaked lime (i.e., Ca(OH) 2) and straw retention on NH 3 emissions and NH 3 emission factors (EFs) in a double-cropped rice field. The results showed that compared to unlimed treatments, liming promoted NH 3 emissions and EFs by 98.6% and 90.2% in the early rice growth season, respectively, with increases of 16.3% and 15.7% in the late rice growth season. Relative to straw removal, straw retention increased NH 3 emissions by 52.8% in the early rice growth season but did not alter EFs, while reducing NH 3 emissions by 9.9% and EFs by 25.7% in the late rice growth season. Liming interacted with straw retention to increase NH 3 emissions and EFs in the early rice growth season. Under straw retention, liming promoted NH 3 emissions by 147.7% and EFs by 148.3%, whereas liming raised NH 3 emissions and EFs only by 45.3% and 45.5% under straw removal, respectively. Liming had no significant interactions with straw retention on NH 3 emissions and EFs in the late rice growth season. It is likely that the decomposition extent of straw can alter the response of NH 3 emissions to liming. Thus, NH 3 emission inventories should take into account the interaction of liming and straw retention and its dependence on rice growth seasons in double-cropped rice systems with acidic soils.
The adaptive fuzzy predefined-time tracking control problem for a class of nonlinear systems with output hysteresis is investigated in this article. An inverse model is utilized to capture the output hysteresis phenomenon, and then the Nussbaum-type function technique is utilized to overcome the difficulty of unknown time-varying control gain caused by output hysteresis. An adaptive fuzzy control scheme under the backstepping framework is developed using the predefined-time stability criterion. Different from the existing predefined-time design approaches, the adaptive law designed in this article is represented as a nonlinear differential equation. Theoretical analysis demonstrates that all signals of the closed-loop systems are bounded, and the tracking error can converge to the neighborhood near origin within an expected settling time. The developed scheme's feasibility is verified by an example of an electromechanical system.
Land use change and anthropogenic forcing can drastically alter the rates and patterns of sediment transport and modify biodiversity and ecosystem functions in coastal transition zones, such as the coastal ecosystems. Molecular studies of sediment extracted DNAs provide information on currently living organisms within the upper layers or buried from various periods of time, but might also provide knowledge on species dynamics, replacement and turnover. In this study, we evaluated the eukaryotic communities of a marine core that present a shift in soil erosion that was linked to glyphosate usage and correlated to chlordecone resurgence since 2000. We show differences in community composition between samples from the second half of the last century and those from the last two decades. Temporal analyses of the relative abundance, alpha diversity, and beta diversity for the two periods demonstrated different temporal dynamics depending on the considered taxonomic group. In particular, Ascomycetes showed a decrease in abundance over the most recent period associated with changes in community membership but not community structure. Two photosynthetic groups, Bacillariophyceae and Prasinophytes clade VII, showed a different pattern with an increase in abundance since the beginning of the 21st century with a decrease in diversity and evenness to form more heterogeneous communities dominated by a few abundant OTUs. Altogether, our data reveal that agricultural usages such as pesticide use can have long-term and species-dependent implications for microeukaryotic coastal communities on a tropical island.
Introduction Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC) is a new drug delivery approach to treat peritoneal metastasis. This study evaluated two different devices, one based on aerosolization, the Capnopen ® (CAPNOMED – company) and a second, a prototype named Nebulo ® (GAMIDA - company), based on nebulization. The performance of the two devices were tested for PIPAC distribution and cell penetration of doxorubicin in a sheep model. Methods Doxorubicin was aerosolized for 30 min, using PIPAC into 6 ewes, 3 with Capnopen ® and 3 with Nebulo ®. The number of doxorubicin positive cells was determined using the ratio between doxorubicin fluorescence-positive cell nuclei (DOXO+) over total number of DAPI positive cell nuclei (DAPI+). Penetration depth (μm) was defined as the distance between the luminal surface and the location of the deepest DOXO+ nuclei. Results DOXO+ nuclei were identified in 46% of the samples. All omental samples, directly localized in front of the nebulizer head, had DOXO+ nuclei except one in the Nebulo group. There was no significant difference in penetration depth between the 2 groups. Concerning the peritoneum, 40% showed by microscope analysis a depth > 100 μm in the Capnopen group, versus 5% in the Nebulo group (p = 0.06). Conclusions Our results and limitations observed imposes a change in developing technic. A smaller size of PIPAC droplet is not an efficient option to increase significantly the tissue penetration and concentration of drugs in chemotherapy.
Background: Men who have sex with men (MSM) have an increased risk of infection by pathogens transmitted by the oro-fecal route. Here, we investigated the seroprevalence and incidence of hepatitis E virus (HEV) infection in 416 MSM included in the ANRS IPERGAY PrEP trial. Results: Among the 62 (14.9% (95% CI: [11.6%-18.7%]) seropositive for HEV at inclusion, the only factor associated with testing seropositive for HEV was older age. Geographical origin, use of recreational drugs, number of sexual partners, status for HAV and bacterial sexually transmitted infection (STI) at inclusion were not associated. Among the 342 HEV-seronegative patients with available samples, 9 seroconverted after a median of follow-up of 2.1 years (IQR (interquartile range): [1.6; 3.0]). Conclusion: Overall, the HEV incidence was 1.19% per 100 person-years [95% CI: 0.54%; 2.26%]. Sexual transmission does not seem to be a major route of HEV infection in MSM, unlike HAV.
Suicidal ideation (SI) is a major suicide risk factor; therefore, it is crucial to identify individuals with SI. Discrepancies between the clinicians and patients' estimation of SI may lead to under-evaluating the suicide risk. Yet, studies on discrepancies between self- and clinician-rated SI are lacking, although identifying the patients' sociodemographic and clinical characteristics associated with such discrepancies might help to reduce the under-evaluation risk. Therefore, the aim of this study was to identify features associated with SI rating discrepancies in patients with bipolar disorder (BD) because of the high prevalence of suicide in this population. Among the patients recruited by the French network of FondaMental expert centers for BD, patients with SI (i.e. ≥2 for item 12 of the Quick Inventory of Depressive Symptomatology-Self Report and/or ≥3 for item 10 of the clinician-rated Montgomery and Åsberg Depression Rating Scale) were selected and divided in concordant (i.e. SI in both self- and clinician-rated questionnaires; n = 130; 25.6%), and discordant (i.e. SI in only one questionnaire; n = 377; 74.4%). Depression severity was the feature most associated with SI evaluation discrepancy, especially in patients with SI identified only with the self-rated questionnaire. Clinician may under-evaluate SI presence in patients with low depression level.
Rice yields in Uruguay have increased rapidly (159 kg⁻¹ ha⁻¹ y⁻¹) between 1990 and 2013. There is evidence, however, of an incipient yield plateau in recent years. The aim of this study was to determine if the recent slowdown in yield gains is because average yield (Ya) has approached the yield potential (Yp) ceiling, which makes it increasingly difficult for farmers to sustain further yield gains. We followed the methodology developed by the Global Yield Gap Atlas to estimate Yp and associated yield gaps for irrigated rice supported by data from high-yield experiments to calibrate the rice simulation model Oryza (v3). Subsequently, the model was used to simulate Yp using long-term daily weather data from seven locations, representing 90 % of total rice area in Uruguay. The exploitable yield gap (Yeg) was calculated as the difference between 80 % of Yp and Ya. Estimated national average Yp was 13.9 Mg ha⁻¹, with relatively small variation across sites, from 13.1 to 15.1 Mg ha⁻¹. Average Ya was 8.3 Mg ha⁻¹, ranging from 7.9 to 8.5 Mg ha⁻¹ across sites, and representing 60 % of Yp. Our analysis suggests there is still room to further increase rice yields in Uruguay, because the Yeg is 2.8 Mg ha⁻¹, which means the current yield plateau is not due to Ya approaching Yp, as has occurred in other high-yield irrigated rice systems in China and California, USA. The approach followed here can help determine whether yield plateaus are occurring due to a small Yeg or other factors.
Objectives: To estimate the proportion of users of the TousAntiCovid app(lication) and identify factors associated with its non-use for contact tracing. Methods: We conducted an online survey of a quota sample of French adults between 8 and 18 January 2021. Three categories of TousAntiCovid use were considered: contact tracing, other or temporary usage, and no use. A weighted multiple logistic regression was performed to analyze the factors associated with these different uses. Results: Among the 1000 respondents, 63.3% declared they had never downloaded the TousAntiCovid app, 23.5% used it for contact tracing. The remaining 13.2% did not enable contact tracing, mainly because of excessive battery consumption and fear of misuse of personal data. Trust in political representatives, financial deprivation and other factors were associated with never downloading the app. Conclusion: This study confirms the previously suggested links between trust in political representatives, financial deprivation and the use of contact tracing apps in France.
The base excision repair (BER) pathway involves sequential action of DNA glycosylases and apurinic/apyrimidinic (AP) endonucleases to incise damaged DNA and prepare DNA termini for incorporation of a correct nucleotide by DNA polymerases. It has been suggested that the enzymatic steps in BER include recognition of a product-enzyme complex by the next enzyme in the pathway, resulting in the "passing-the-baton" model of transfer of DNA intermediates between enzymes. To verify this model, in this work, we aimed to create a suitable experimental system. We prepared APE1 site-specifically labeled with a fluorescent reporter that is sensitive to stages of APE1-DNA binding, of formation of the catalytic complex, and of subsequent dissociation of the enzyme-product complex. Interactions of the labeled APE1 with various model DNA substrates (containing an abasic site) of varied lengths revealed that the enzyme remains mostly in complex with the DNA product. By means of the fluorescently labeled APE1 in combination with a stopped-flow fluorescence assay, it was found that Polβ stimulates both i) APE1 binding to an abasic-site-containing DNA duplex with the formation of a catalytically competent complex and ii) the dissociation of APE1 from its product. These findings confirm DNA-mediated coordination of APE1 and Polβ activities and suggest that Polβ is the key trigger of the DNA transfer between the enzymes participating in initial steps of BER.
Removal/reinstallation of all Test Blanket System (TBS) equipment present in the Port Cell is required during the ITER Long Term Shutdown. TBS shall be designed so that occupational radiation exposure can be As Low As Reasonably Achievable (ALARA) over the life of the plant to follow the ITER Policy. The expected level of radiation in this area still allows performing maintenance tasks hands-on. However, the cumulated dose could be significant for operators. Classical Dose Reduction Measure (DRM) is to deploy Remote Handling systems. Consequently, use of robotized equipment, remotely operated means or collaborative robotics, have been investigated. Taking advantage of new digital technologies such as digital assistances, is expected to help operators during complex remote operations under limited vision conditions. Experiments were performed on a set of three TBS maintenance representative tasks: remote visual inspection of DN80 pipe, dye penetrant testing operation on pipe and dexterity test. A panel of remote handling equipment operators of different skill level was selected and involved onto these tasks. The results prove without ambiguity that for all operators the quality of the task execution is significantly improved when using digital assistances
This book examines the European Left’s attempt to think and give shape to an alternative type of European integration—a ‘social Europe’—during the long 1970s. Based on fresh archival research, it shows that the western European Left—in particular, social democratic parties, trade unions, and to a lesser extent ‘Eurocommunist’ parties—formulated a broad project to turn ‘capitalist Europe’ into a ‘workers’ Europe’. This alternative model of European unity favoured coordinated measures for wealth redistribution, market regulation, a democratization of the economy and of European institutions, upward harmonization of social and fiscal systems, more inclusive welfare regimes, guaranteed employment, economic and social planning with greater consideration for the environment, increased public spending to meet collective needs, greater control of capital flows and multinational corporations, a reduction in working time, and a fairer international economic order favouring the global South. During the pivotal years following 1968, deeply marked by labour militancy, new social movements, economic crisis, and the unmaking of the ‘postwar compromise’, a window of opportunity opened in which European integration could have taken different roads. The defeat of ‘social Europe’ was a result of a decade-long social conflict which ended with the affirmation of a neoliberal Europe. Investigating this forgotten power struggle and the reasons of its defeat can be useful not just to scholars and students eager to understand the historical evolution of European integration, the European Left, and European capitalism, but also to anyone interested in building alternative European and global futures.
We report on a comprehensive experimental and theoretical study of the Fe1−xRhxGe compounds, within the entire concentration range x ∈ [0.0 − 1.0], using X-Ray diffraction, small-angle neutron scattering, magnetometry and theoretical calculations. While FeGe and RhGe are single phase helimagnet and unconventional superconductor, respectively, an internal splitting of the crystallographic and magnetic states is found for intermediate compositions x ∈ [0.2 − 0.9]. A theoretical analysis of the stability of the two detected phases, together with the experimental data, indicate that this splitting preserves a common space group and occurs within single crystallites. Despite their apparent similarity, these two phases however display different magnetic structures, with distinct ferro- and helimagnetic character.
Vibrations of fuel assemblies are an important issue in the safe operation of nuclear reactors, because they can challenge the integrity of the fuel with potential for radioactive releases. Reactor neutron noise-based techniques for monitoring vibrations are valuable for core diagnostic since they are not intrusive and make use of ordinary neutron flux measurements from ex-core and in-core detectors. The application of these techniques involves the solution of inverse problems that require numerical simulations capable of estimating the reactor neutron noise, given a model of the vibrations. For this purpose, several novel reactor neutron noise solvers have been developed in the CORTEX project using either Monte Carlo or deterministic methods, such as the discrete ordinates method, the method of characteristics, and the diffusion approximation. In the current work, these solvers have been scrutinized by computing the neutron noise induced by vibrations of one or multiple fuel pins in a simplified UOX fuel assembly benchmark, via proper variations of macroscopic neutron cross sections. The comparison of these neutron noise solutions obtained from the different methods shows novel insights into the simulation of neutron noise induced by mechanical vibrations, such as the challenges posed by the Monte Carlo method, the impact of the angular discretization on the application of the discrete ordinates method, and the accuracy of the diffusion approximation assessed via the higher-order neutron transport methods.
We have studied the temperature-dependent electronic structure of the light rare-earth antimonide LaSb2 by combining angle-resolved photoemission (ARPES) measurements and density functional theory (DFT) calculations. ARPES measurements show the appearance of band replicas in the low-temperature Fermi surface with q = 0.25 ± 0.02 A⁻¹ and a band folding of the same periodicity with a considerable spectral weight in the folded band. From our calculations we elucidate that the folded band exhibiting the new periodicity is associated with the La-Sb layer. We propose that an in-plane distortion, probably affecting the whole unit cell, is the structural modification related to the electronic changes. All these results converge to support that a charge density wave is stabilized in LaSb2 at low temperature.
This study evaluates the impact of ethanol content on both regulated and non-regulated emissions with recent vehicle technologies. The three vehicles used here are complying with Euro 6d-temp or Euro 6c emission standards and are adapted to variable ethanol concentrations, either through flex-fuel or E85 conversion kit. Both regulated and non-regulated emissions are characterized to highlight the fuel and vehicle technology impacts. The analysis of non-regulated pollutants in exhaust gases is performed with three different techniques to evaluate their advantages or limitations and assess time-resolved emission levels. HPLC coupled to UV detection to measure aldehydes and ketones. GC–MS was used for PAHs characterization. GC-FID was used to measure VOCs (C1 to C12) on the first phase of the WLTC. FTICR-MS was used to assess time-resolved emission levels. Results indicate a negligible impact on the emissions for ethanol content from 10 to 20% vol. Nevertheless, a significant emission composition variation is observed at 50% vol., and this is even more pronounced with 85% vol. of ethanol. Expected trends based on the literature review are confirmed for all vehicles and this includes an increase in unburned ethanol and aldehydes emissions with higher ethanol content while in this condition lower aromatics contribute to reduce particulate matters emissions. The use of varying amounts of ethanol in recent and diverse Euro 6d-temp vehicle technologies shows that the increase in ethanol content is unaffected by the reduction in particulate emissions and the increase in the finest. However, the results indicate a risk of increased NOx emissions for Euro 6d-temp IC engines, which should be confirmed on other vehicles of similar technology. This study results also indicate that most pollutants are emitted in the engine and exhaust warm-up phase. All analytical techniques exhibited similar trends.
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Christophe Poulard
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