Search results for "surface"
showing 10 items of 9345 documents
Guiding and confinement of interface acoustic waves in solid-fluid pillar-based phononic crystals
2016
International audience; Pillar-based phononic crystals exhibit some unique wave phenomena due to the interaction between surface acoustic modes of the substrate and local resonances supported by pillars. In this paper, we extend the investigations by taking into account the presence of a liquid medium. We particularly demonstrate that local resonances dramatically decrease the phase velocity of Scholte-Stoneley wave, which leads to a slow wave at the solid/fluid interface. Moreover, we show that increasing the height of pillars introduces a new set of branches of interface modes and drastically affects the acoustic energy localization. Indeed, while some modes display a highly confined pres…
Nanovector formation by functionalization of TRAIL ligand on single-walled carbon nanotube: Experimental and theoretical evidences
2015
Équipe 104 : Nanomatériaux; International audience; The synthesis and the characterization of a novel nanovector based on oxidized single-walled carbon nanotubes (SWCNT) functionalized with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) via noncovalent 1-pyrenebutanoic acid N-hydrosuccinimid ester (PSE) is described. Experimental noncovalent functionalized SWCNT by PSE are compared to full DFT theoretical predictions. For this, several experimental techniques are gathered to prove the well functionalization of oxidized SWCNT by pi-pi stacking such as micro Raman and XPS spectroscopy analysis coupled to full-DFT calculations. Scanning transmission electron microscopy (STEM) …
Single crystal EXAFS at high pressure
2000
Abstract We present a new technique for structure characterization under high pressure conditions. The use of an undulator beam of the third-generation ESRF source of synchrotron radiation has enabled the first single crystal EXAFS experiments at high pressure using a diamond anvil cell as pressure generator. Taking advantage of the linear polarization of X-rays the technique becomes an orientation-selective probe of the local structure of materials. We describe the principle of the technique and some applications.
Surface plasmon interference excited by tightly focused laser beams
2007
International audience; We show that interfering surface plasmon polaritons can be excited with a focused laser beam at normal incidence to a plane metal film. No protrusions or holes are needed in this excitation scheme. Depending on the axial position of the focus, the intensity distribution on the metal surface is either dominated by interferences between counterpropagating plasmons or by a two-lobe pattern characteristic of localized surface plasmon excitation. Our experiments can be accurately explained by use of the angular spectrum representation and provide a simple means for locally exciting standing surface plasmon polaritons.
Application of a simple algorithm to estimate daily evapotranspiration from NOAA–AVHRR images for the Iberian Peninsula
2007
International audience; Evapotranspiration (ET) is a key process in land surface–atmosphere studies. It mainly depends on water availability and incoming solar radiation and then reflects the interactions between surface water processes and climate. In this paper, a methodology for retrieving ET from low spatial resolution remote sensing data is presented. It is based on the evaporative fraction concept, and it has been applied to Advanced Very High Resolution Radiometer (AHVRR) data acquired over the Iberian Peninsula. The methodology does not require other data than the data provided by the satellite and may be applied to areas with almost spatially constant atmospheric conditions and whi…
The EuroSTARRS airborne campaign in support of the SMOS mission: first results over land surfaces
2004
A number of experiments using ground-based and airborne sensors have shown the high potential of L-band passive microwave radiometry for estimating and monitoring surface soil moisture. This has led to the Soil Moisture and Ocean Salinity (SMOS) mission, a European Space Agency (ESA) Earth Explorer Opportunity mission. SMOS has the objective to observe soil moisture over land and sea surface salinity over sea, both key parameters for atmospheric, oceanographic and hydrological predictive models. In preparation of SMOS, the EuroSTARRS airborne campaign was carried out in November 2001. Multi-angular measurements of the surface brightness temperature at L-band (1.4 GHz) at vertical polarizati…
Retrieval of evapotranspiration over the Alpilles/ReSeDA experimental site using airborne POLDER sensor and a thermal camera
2005
Abstract Knowledge of land surface evapotranspiration is of prime interest for environmental applications, such as optimizing irrigation water use, especially in arid and semiarid rangelands where water shortage is a critical problem. Numerous methods aiming at estimating evapotranspiration have been proposed in the literature. In the current paper, we assess the potential of the evaporative fraction based on the S-SEBI (Simplified Surface Energy Balance Index) concept for estimating instantaneous evapotranspiration, and extend this potential to the retrieval of daily evapotranspiration (ETd). To this end, a feasible and operational method is developed, which allows mapping instantaneous an…
Gas sensors arrays (electronic noses) : a study about the speed/accuracy ratio
2000
Abstract New Fingerprint Mass Spectra (FMS) systems claim for a higher precision, a reduced analysis time, and a lower drift, compared with Gas Sensors Arrays ‘Electronic Noses’. We demonstrated in this study that metal oxide gas sensors may have highly improved performances for both accuracy and run time, when used in optimum conditions. The different noise components were quantified referring to popular words (equivalent of ethanol concentration) using the transfer function of the sensor. It was pointed out that sample surrounding greatly affects the noise level, and that the signal-to-noise ratio may be dramatically increased, reducing the distortion generally assessed between sensor and…
Noise Analysis and Comparison of Phase-and Frequency-Detecting Readout Systems: Application to SAW Delay Line Magnetic Field Sensor
2019
International audience; Transmission surface acoustic wave (SAW) sensors are widely used in various fields of application. In order to improve the limit of detection (LOD) of such sensor systems, it is essential to understand and quantify the relevant noise sources. Only then, strategies for noise reduction can be developed. In this paper, low noise readout systems for the application with SAW sensors in an open-loop and a closed-loop configuration are presented and experimentally investigated with regard to their phase noise on the example of a SAW delay line magnetic field sensor. Besides a comprehensive analysis of the phaseand frequency modulated signals, respectively, previously derive…
Electronic noses : specify or disappear
2000
Abstract When the quality control is achieved by using GC or GC/MS, the apparatus must comply with the applicable norms, but what about “electronic noses”? End users demand for formal specifications for selectivity, sensitivity, repeatability and sample throughput. The behavioural modelling of electronic olfactometers may provide specifications for these required parameters. This will allow both the measure itself, and evaluate the influence of the experimental errors on the sample classification. Users may expect to find a methodology allowing the performances of systems to be checked before any final decision and during routine use. We have demonstrated that the system sensitivity and log…