Coupling efficiency for phase locking of a spin transfer oscillator to a microwave current

The phase locking behavior of spin transfer nano-oscillators (STNOs) to an external microwave signal is experimentally studied as a function of the STNO intrinsic parameters. We extract the coupling strength from our data using the derived phase dynamics of a forced STNO. The predicted trends on the coupling strength for phase locking as a function of intrinsic features of the oscillators i.e. power, linewidth, agility in current, are central to optimize the emitted power in arrays of mutually coupled STNOs

Joule heating and high frequency nonlinear effects in the surface impedance of high Tc superconductors

Using the dielectric resonator method, we have investigated nonlinearities in the surface impedance Zs = Rs + jXs of YBa2Cu3O7 thin films at 10 GHz as function of the incident microwave power level and temperature. The use of a rutile dielectric resonator allows us to measure the precise temperature of the films. We conclusively show that the usually observed increase of the surface resistance of YBa2Cu3O7 thin film as function of microwave power is due to local heating

Digestate color and light intensity affect nutrient removal and competition phenomena in a microalgal-bacterial ecosystem

International audienceDuring anaerobic digestion, nutrients are mineralized and may require post-treatment for optimum valorization. The cultivation of autotrophic microalgae using the digestate supernatant is a promising solution; however the dark color of the influent poses a serious problem. First, the color of the digestates was studied and the results obtained using three different digestates demonstrated a strong heterogeneity although their color remained rather constant over time. The digestates absorbed light over the whole visible spectrum and remained colored even after a ten-fold dilution. Secondly, the impact of light and of substrate color on the growth of Scenedesmus sp. and on nitrogen removal were assessed. These experiments led to the construction of a model for predicting the impact of influent color and light intensity on N removal. Maximum N removal (8.5mgN-NH4+L-1d-1) was observed with an initial optical density of 0.221 and 244?molEm-?s-1 light and the model allows to determine N removal between 15.9 and 22.7mgN-NH4+L-1d-1 in real conditions according to the dilution level of the influent and related color. Changes in the microalgae community were monitored and revealed the advantage of Chlorella over Scenedesmus under light-limitation. Additionally microalgae outcompeted nitrifying bacteria and experiments showed how microalgae become better competitors for nutrients when phosphorus is limiting. Furthermore, nitrification was limited by microalgae growth, even when P was not limiting. © 2014

Design of microalgae process for nutrient extraction from digestate through laboratory tests and modelling

International audienceMicroalgae culture for extraction of nutrient from digestate was studied at laboratory scale to determine the influence of turbidity of influent, light provided, N:P of the influent, CO2 supplementation and solid retention time on microalgae productivity and associated N removal processes. The experimental results obtained in batch and semi-continuous mode showed the importance of turbidity of influent combined with light intensity on the microalgae roductivity compared to the impact of the level of CO2 supplementation and N:P ratio. Additionally to N assimilation by microalgae, nitrification-denitrification was identified as a major N pathway with N removal at least equal to N assimilation. However, limitation of nitrification process appears possible through the N:P ratio of the influent. The evolution of microalgae communities observed during these trials highlighted the interest of using mix culture allowing a better adaption to the conditions evolutions. Finally, all experimental results were used to build and calibrate a model simulating microalgae growth using nutrients from digestate and such a model was used to design a raceway pond treating digestate from a commercial farm producing 4000 pigs per year

Design of microalgae process for nutrient extraction from digestate through laboratory tests and modelling

International audienceMicroalgae culture for extraction of nutrient from digestate was studied at laboratory scale to determine the influence of turbidity of influent, light provided, N:P of the influent, CO2 supplementation and solid retention time on microalgae productivity and associated N removal processes. The experimental results obtained in batch and semi-continuous mode showed the importance of turbidity of influent combined with light intensity on the microalgae roductivity compared to the impact of the level of CO2 supplementation and N:P ratio. Additionally to N assimilation by microalgae, nitrification-denitrification was identified as a major N pathway with N removal at least equal to N assimilation. However, limitation of nitrification process appears possible through the N:P ratio of the influent. The evolution of microalgae communities observed during these trials highlighted the interest of using mix culture allowing a better adaption to the conditions evolutions. Finally, all experimental results were used to build and calibrate a model simulating microalgae growth using nutrients from digestate and such a model was used to design a raceway pond treating digestate from a commercial farm producing 4000 pigs per year

Suppression of the “notch effect” in microwave surface resistance in

RHEED controlled ultra-thin buffer layers of SrTiO3 have been deposited on (100) MgO by pulsed laser deposition to growth YBaCuO films for microwave applications. A buffer layer with a thickness between 2 and 15 nm, i.e. 5 to 40 unit cells of SrTiO3, is sufficient to expand to more than 60 °C the range of deposition temperatures leading to low microwave surface resistance. The Rs values are as good as those obtained on LaAlO3 substrates with a slighly lower magnetic field dependency. The SrTiO3 seed layer induces an oriented epitaxial growth with YBCO [100] // MgO [100] over this range of deposition temperatures

Concept of Superconducting Pipeline A/D Converter

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Dynamic bio-kinetic modelling of microalgae/bacteria cultivation and interaction

International audienceCultivation of microalgae in wastewater and digestate has received special attention during the last years due to the potential for nutrient, CO2 and/or heat recovery and recycling. However, understanding microalgae-bacteria interactions remains a major concern for process operation and control. This paper aims to develop a new mathematical process model in the IWA activated sludge model (ASM) framework, including microalgae cultivation, heterotrophic and autotrophic bacteria interactions, as well as pH dynamics. The model should allow to develop optimization and control strategies of microalgae processes for nutrient, CO2 and heat recovery. In this paper, the model was verified and calibrated under dynamic conditions. Mass balances were closed for nitrogen, phosphorus and carbon elements, whereas also the overall dynamics were satisfying. Finally, future research efforts were identified

Postmortem degradation of white fish skeletal muscle (Sea bass, Dicentrarchus labrax) : fat diet effects on in situ dystrophin proteolysis during the prerigor stage

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