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Evaluating the sustainability of pv technologies and their cooling systems: a life cycle assessment review
No full textInternational audienceLife cycle environmental consequences of photovoltaic systems, from raw material extraction to end-of-life (EoL) management, have attracted more interest in recent years. Life Cycle Assessment (LCA) is a vital tool to analyze the sustainability of PV panels based on parameters such as energy payback time (EPBT), greenhouse gas emissions (GHG), and cumulative energy demand (CED). Several studies have considered standalone PV technologies, while the environmental ramifications of integrating cooling systems have not been adequately investigated, even with their increasing relevance in enhancing PV efficiency and lifespan. This review fills the identified gap by systematically assessing the life cycle performance of the PV technologies considered here, alongside several cooling methods - air-based, liquid-based, phase change materials (PCM), radiative, and hybrid systems - for their combined performance, economic, and environmental trade-offs. Results show that Cadmium Telluride and Copper Indium Gallium Selenide technologies exhibit low energy payback times and global warming potential (GWP). Water-based cooling shows the lowest GWP, although water use remains a cause for concern. PCM cooling provides long-term energy savings but comes with recyclability issues. High-value EoL management with recycling would lower GWP. With these fragmented LCA findings, the review provides a common framework for assessing the PV cooling technologies and also provides a case of the need for consolidated datasets and harmonized methodologies. Future research needs to enhance the LCA databases relating to PV cooling systems and establish policy-driven steps to support circularity and sustainable pathways for PV technology
Screening of exoenzymes for guar gum biodegradation in activated sludge and soil
No full textInternational audienceOriginally standardized biodegradation tests, designed for small molecules, are often considered inadequate for evaluating polymers, as they do not account for the crucial fragmentation step catalyzed by exoenzymes, which is essential for initiating the microbial degradation of polymers. In this study, the presence of EEs in the environment and their role in the biodegradation of guar gum, a WSP, were evaluated. A metagenomic shotgun approach assessed the abundance of genes encoding α-galactosidase and β-mannosidase in the Waste Water Treatment Plant (WWTP) and soil. Secondly, we employed sonication to release EEs, measured their activity, and evaluated the impact of their release on guar degradation using biodegradation tests. These findings indicated that genes encoding α-galactosidase and β-mannosidase were more abundant in the WWTP than in soil. A sonication protocol with a power density of 1 W/mL and a frequency of 20 kHz for 1 min (WWTP) and 2 min (soil) released EEs without significant cell lysis and significantly reduced the lag phase of guar-grafted acrylamide biodegradation from 8 to 5 days and decreased variability in native guar biodegradation by 10%. Our findings highlight the potential of WWTP and soil microbial communities to degrade guar gum by screening EEs and propose a new method for preparing the inoculum for WSPs biodegradation tests
"Kangxi et Louis XIV" 《康熙与路易十四》
No full textInternational audienceL’année 2024 marque le 60e anniversaire de l'établissement des relations diplomatiques entre la Chine et la France. Les relations culturelles entre les deux pays remontent aux premières années de la dynastie Qing et à une figure centrale, celle de Joachim Bouvet (1656-1730), appelé Bai Jin par les Chinois mais également Ming Yuan, qui fut l'un des cinq premiers missionnaires jésuites envoyés en Chine par le roi de France Louis XIV. Arrivé en Chine en 1687, il mourut à Pékin et fut enterré dans le cimetière du temple de Zhengfu également connu sous le nom de cimetière français. Grâce à ses réalisations pionnières dans de nombreux domaines, Joachim Bouvet a toujours été la figure la plus observée parmi les missionnaires français en Chine
Online measurement of differential drain to source voltage for SiC MOSFETS power module
No full textInternational audienceThe on-state resistance RDSON is a key aging indicator of silicon carbide MOSFETs power module. It can provide information on both chip and packaging degradation allowing more reliable power electronic converter. This on-state resistance can be determined using both the on-state current and voltage of the power semiconductor. This paper focuses on an on-state voltage measurement circuit for SiC MOSFET power module. In the literature, power module bondwires resistance cannot be measured due to high switching voltage oscillations. An on-state voltage measurement circuit that can withstand such oscillations is proposed. The proposed circuit is characterized using the ISO 5725 standard over a wide temperature range. Finally, the circuit is successfully tested on a double pulse bench for various module base plate temperatures and compared to data obtained with a static curve tracer Keysight B1505
Differences in Persistent Inward Current Contribution to Spinal Motor Neuron Behaviour Between Early Morning and Late Afternoon
No full textInternational audienceDespite the critical role of persistent inward currents (PICs) in modulating motor neuron output, and thus neuromuscular performance, it remains unknown whether their contribution to motor neuron discharge behaviour varies throughout the day. This study aimed to determine whether PIC-related effects on motor neuron activity during submaximal dorsiflexion tasks differ between the early morning and late afternoon. Eighteen healthy adults (4 females; 27.4±5.6 years) performed triangular isometric contractions at two randomized time-points on separate days: early morning (7:00–8:30a.m.) and late afternoon (5:00–7:30p.m.). Two conditions were tested: (1) a relative condition, where the target force corresponded to 40% of the maximal voluntary force (MVF) measured during that session, and (2) an absolute condition, where the target force was 40%MVF recorded during the first session. High-density surface electromyography signals were recorded from the tibialis anterior and decomposed into motor unit spike trains. The prolongation effect of PICs, estimated via ΔF, was significantly greater in the late afternoon in both the relative-absolute force conditions. The amplification effect of PICs, estimated by the acceleration phase of the discharge trajectory, was higher in the late afternoon, but only in the relative force condition. Brace height did not differ between morning and afternoon, but attenuation was lower in the late afternoon during the relative force condition. Collectively, these findings suggest a time-of-day modulation of PIC contribution to motor neuron discharge behaviour, likely mediated by a change in inhibitory–excitatory balance between early morning and late afternoon rather than by changes in neuromodulatory drive
The Role of Ritual and Craft Production in Social Interaction and Elite Empowerment in a Mixed Centre during the South Italian Iron Age
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Constraints on Solar Reflected Dark Matter from a combined analysis of XENON1T and XENONnT data
No full textInternational audienceWe report on a search for sub-GeV dark matter upscattered via the solar reflection mechanism in the heavy mediator scenario. Under the Standard Halo Model, keV to MeV dark matter produces nuclear recoils with energies below the detection threshold of liquid xenon time projection chambers. We enhance sensitivity to low-mass dark matter by considering dark matter-electron scattering, employing dedicated event selections to reduce the detection threshold, and exploiting the additional kinetic energy imparted to the dark matter particle by solar upscattering. Using XENON1T ionization-only and XENONnT low-energy electronic recoil datasets, we exclude previously unconstrained DM-electron scattering cross section for masses between and , and between and , reaching a minimum of for a mass of at 90% confidence level
Study of Decay Shape Factors in First-Forbidden Transitions with for Reactor Antineutrino Spectra Predictions
No full textInternational audienceThe electron spectra of the decays of Rb and Cs, key contributors to the reactor antineutrino spectrum, were measured at the IGISOL facility using radioactive beams of high isotopic purity. The shapes of the measured spectra were compared with various shape models, including first-forbidden correction factors for ground-state to ground-state transitions. Comparisons with previous experimental results are also provided. The shapes of the newly measured spectra are well reproduced employing feedings extracted from total absorption gamma spectroscopy measurements
Assessment and mitigation of the effects of waves and wind gusts on power production of an energy ship
No full textInternational audienceThis study investigates the dynamic behavior and power performance of an energy ship designed to harvest offshore wind energy through wind propulsion and onboard hydrokinetic turbines. A nonlinear dynamic model, validated at model scale, is used to assess the influence of waves and wind gusts on power generation. Simulations accounting for wave effects show that, while wave-induced dynamics generate power fluctuations of up to approximately 2%, their impact on mean power production remains limited, with a reduction of less than 1%. The most constraining conditions are associated with wave periods close to the surge resonance of the vessel. Simulations taking into account wind gusts reveal that transient overproduction may arise under nominal operation, exceeding up to 120% the maximum allowable power. Thus, a combined control strategy-adjusting both the hydrokinetic turbine rotational speed and ship heading is introduced. It is shown that it can successfully maintain power, torque, and rotational speed within safe operating limits, while enabling an energy gain of 6-10% during gust events.The results highlight the need to consider unsteady environmental effects when designing energy ship control systems and demonstrate the effectiveness of the proposed strategy in ensuring safe and efficient operation under realistic sea conditions
SiC MOSFET gate oxide degradation monitoring: a gate leakage current approach
No full textInternational audienceThis paper deals with online measurement of degra-dation sensitive electrical parameters leading to a health mon-itoring approach for silicon carbide power MOSFETs. Thegate leakage current IGSS is chosen as a key indicator of thesilicon carbide MOSFET gate oxide degradation as it providesinformation on its gate dielectric breakdown time. Due to thelow amplitude of gate leakage current, on-line measurement ofIGSS presents critical challenges because of the high transientcurrent flowing through the gate during normal operation time.This paper presents an improved estimation circuit from analready existing one using the gate driver circuit. The proposedcircuit is characterised under various VGS conditions for differenttemperatures. Finally, the circuit is successfully tested on anelectronic chopper circuit for various Pulse Width Modulation(PWM) signal duty cycles