Distributed Consensus Control of DFIGs with Storage for Wind Farm Power Output Regulation

Today the state-of-the-art (SoA) wind generators (WGs) are the double-fed induction (DFIGs) with integrated storage devices. In the future, these WGs are expected to be one of the largest producers of renewable energy worldwide. In this paper, we propose a distributed control methodology for solving the problem of coordinating and controlling a group of SoA WGs to attain fast wind farm (WF) power output regulation with each storage device providing the same amount of power, i.e with equal sharing among the storage devices. Our proposed methodology introduces a consensus protocol for coordinating the grid-side converters (GSCs), whose dynamical equations constitute their closed-loop dynamics, and a particular closed-loop form for the interfacing capacitor dynamics. We establish stability of these closed-loop dynamics by leveraging singular perturbation and Lyapunov theories, proving that with these closed-loop dynamics DFIGs accomplish their assigned control objectives. Finally, we analytically construct a distributed and a Control Lyapunov Function (CLF) -based control law for the GSC and the DCDC converter respectively, which jointly lead to the desired closed-loop dynamics. We demonstrate the effectiveness of our methodology through simulations on the IEEE 24-bus reliability test system (RTS)

CSI: Dognapping workshop : an outreach experiment designed to produce students that are hooked on science.

The CSI: Dognapping Workshop is a culmination of the more than 65 Sandian staff and intern volunteers dedication to exciting and encouraging the next generation of scientific leaders. This 2 hour workshop used a 'theatrical play' and 'hands on' activities that was fun, exciting and challenging for 3rd-5th graders while meeting science curriculum standards. In addition, new pedagogical methods were developed in order to introduce nanotechnology to the public. Survey analysis indicated that the workshop had an overall improvement and positive impact on helping the students to understand concepts from materials science and chemistry as well as increased our interaction with the K-5 community. Anecdotal analyses showed that this simple exercise will have far reaching impact with the results necessary to maintain the United States as the scientific leader in the world. This experience led to the initiation of over 100 Official Junior Scientists

Age, Disease Severity and Ethnicity Influence Humoral Responses in a Multi-Ethnic COVID-19 Cohort

The COVID-19 pandemic has affected all individuals across the globe in some way. Despite large numbers of reported seroprevalence studies, there remains a limited understanding of how the magnitude and epitope utilization of the humoral immune response to SARS-CoV-2 viral anti-gens varies within populations following natural infection. Here, we designed a quantitative, multi-epitope protein microarray comprising various nucleocapsid protein structural motifs, including two structural domains and three intrinsically disordered regions. Quantitative data from the microarray provided complete differentiation between cases and pre-pandemic controls (100% sensitivity and specificity) in a case-control cohort (n = 100). We then assessed the influence of disease severity, age, and ethnicity on the strength and breadth of the humoral response in a multi-ethnic cohort (n = 138). As expected, patients with severe disease showed significantly higher antibody titers and interestingly also had significantly broader epitope coverage. A significant increase in antibody titer and epitope coverage was observed with increasing age, in both mild and severe disease, which is promising for vaccine efficacy in older individuals. Additionally, we observed significant differences in the breadth and strength of the humoral immune response in relation to ethnicity, which may reflect differences in genetic and lifestyle factors. Furthermore, our data enabled localization of the immuno-dominant epitope to the C-terminal structural domain of the viral nucleocapsid protein in two independent cohorts. Overall, we have designed, validated, and tested an advanced serological assay that enables accurate quantitation of the humoral response post natural infection and that has revealed unexpected differences in the magnitude and epitope utilization within a population

Common femoral artery intima-media thickness as marker for cardiovascular disease in asymptomatic adults

Background: The common carotid intima-media thickness (IMT) is considered as a marker of cardiovascular disease, while the value of the common femoral IMT is not well defined. The aim of the present study was to investigate the value of common femoral IMT alone or in combination with the common carotid IMT as a marker of cardiovascular disease in asymptomatic adults. Patients and Methods: Eighty-three individuals with no history of cardiovascular disease were subjected to IMT measurement of both common carotid and common femoral arteries with high-resolution ultrasonography. The Framingham Heart Study (FHS) risk score was calculated for each subject (according to gender) and was correlated with the carotid IMT, femoral IMT, and the combined IMT measured at both arterial sites. Results: The carotid and femoral IMT separately and in combination were found to be correlated with the FHS risk score, calculated based on either the total cholesterol or low density lipoprotein plasma levels (carotid IMT: r = 0.28, p = 0.035, and r = 0.35, p = 0.007, respectively, femoral IMT: r = 0.38, p = 0.003, and r = 0.43, p = 0.001, respectively, carotid-femoral IMT: r = 0.37, p = 0.005, and r = 0.46, p = 0.0001, respectively). In addition, femoral IMT was found to be correlated with the carotid IMT (r = 0.41, p = 0.001). Conclusions: Common carotid and common femoral IMT showed similar correlation with the FHS risk score. Additionally, the combination of IMT from both arterial sites was found to have similar correlation with the FHS risk score to carotid IMT alone

Mesure de la diffusivité de l’oxygène par inhibition de fluorescence de sondes pyréniques dans la membrane d’érythrocyte enrichie en cholestérol

L’influence du cholestérol sur la diffusibilité de l’oxygène dans les membranes biologiques a été étudiée par inhibition de la fluorescence des acides pyrènebutyrique (PBA) et dodécanoïque (PDA). La « fluidité membranaire », mesurée par polarisation de fluorescence avec des sondes spécifiques de différentes régions membranaires (6, 12-AS, DPH, TMA- DPH), évolue inversement au rapport cholestérol/protéine (C/Pt) et varie en fonction de la région étudiée. La durée de vie du monomère du PDA, mesurée par fluorescence résolue dans le temps, croît avec le rapport C/Pt en absence d’O2. En présence d’O2, les valeurs des constantes d’inhibition dynamique du PDA augmentent avec le rapport C/Pt (diffusivité apparente d’02 accrue). La diffusion d’O, augmenterait uniquement dans la région centrale de la membrane, caractérisée par le PDA. La variation de la solubilité d’O2 dans des domaines restreints de polarité différente pourrait expliquer l’inhibition de fluorescence du PDA

Sprayed Tl-1223 films: formation kinetics and superconducting properties

International audienceTlBa/sub 2/Ca/sub 2/Cu/sub 3/O/sub 9/ superconducting films, 0.5 to 1 /spl mu/m in thickness, have been prepared in a two step process. Using a nitrate solution, a precursor layer with composition Ba/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ is first sprayed on a LaAlO/sub 3/ heated substrate and then thallinated, following a procedure established for bulk samples. The critical temperature of the films ranges from 108 to 113 K, and the critical current density of the best samples reaches 0.7 MA/cm/sup 2/. The reaction kinetics for the formation of the Tl-1223 phase between 880 /spl deg/C and 910 /spl deg/C has been studied for a better control of the grain growth and texture. The effect of fluorine addition on both the microstructure and superconducting properties have been also analyzed