Power Quality Improvement of a Microgrid with a Demand-Side-Based Energy Management System

This chapter addresses the power quality of grid-connected microgrids in steady state. Three different power quality issues are evaluated: the voltage drop, the harmonic distortion, and the phase unbalance. A formulation for an energy management algorithm for microgrids is proposed under the form of a mixed-integer linear optimization including harmonic load flows. It handles both the optimization of the scheduling of all the generation, storage, and load assets, and the resolution of power quality issues at the tertiary level of control by adjusting the levels of certain types of loads within the system. This algorithm is simulated for different scenarios on a conceptual test-case microgrid with residential, industrial, and commercial loads. The results show that the demand-side management mechanism inside the algorithm can adapt efficiently the consumption behavior of certain loads, so that the voltage drop, the voltage total harmonic distortion, and the voltage unbalance factor meet the required standards at every node of the microgrid during the day. It is also highlighted that the microgrid can gradually reduce the purchase of power from the utility grid to which it is connected if the electricity price on the spot market increases

Sept élections et peu de changements

2014 a été une année électorale particulièrement chargée pour l’Amérique latine, avec sept élections présidentielles et d’importantes élections législative (Colombie) et locale (Pérou). Dans l’ensemble, l’Amérique latine a connu plus de continuité que de changement, et la gauche demeure la force politique dominante du continent. Dans quel contexte se sont déroulées ces élections ? Comment caractériser l’offre électorale et les stratégies de campagne ? Comment expliquer ces résultats ? Et quelles perspectives générales se dégagent ? Telles sont les questions abordées dans cette partie

Glucose use and lactate production by equine fresh semen in human and equine extender

This study shows that this human semen extender doesn’t support equine semen preservation. Sperm cells’ glucose consumption and lactate production seem to be negligible, as these parameters were not affected by sperm concentrations in our study. Our results suggest that spermatozoa are able to cleave complex carbohydrates as glucose concentration in INRA96 increased over time

The VLTI / PIONIER near-infrared interferometric survey of southern T Tauri stars. I. First results

Context : The properties of the inner disks of bright Herbig AeBe stars have been studied with near infrared (NIR) interferometry and high resolution spectroscopy. The continuum and a few molecular gas species have been studied close to the central star; however, sensitivity problems limit direct information about the inner disks of the fainter T Tauri stars. Aims : Our aim is to measure some of the properties of the inner regions of disks surrounding southern T Tauri stars. Methods : We performed a survey with the PIONIER recombiner instrument at H-band of 21 T Tauri stars. The baselines used ranged from 11 m to 129 m, corresponding to a maximum resolution of 3mas (0.45 au at 150 pc). Results : Thirteen disks are resolved well and the visibility curves are fully sampled as a function of baseline in the range 45-130 m for these 13 objects. A simple qualitative examination of visibility profiles allows us to identify a rapid drop-off in the visibilities at short baselines in 8 resolved disks. This is indicative of a significant contribution from an extended contribution of light from the disk. We demonstrate that this component is compatible with scattered light, providing strong support to a prediction made by Pinte et al. (2008). The amplitude of the drop-off and the amount of dust thermal emission changes from source to source suggesting that each disk is different. A by-product of the survey is the identification of a new milli-arcsec separation binary: WW Cha. Spectroscopic and interferometric data of AK Sco have also been fitted with a binary and disk model. Conclusions : Visibility data are reproduced well when thermal emission and scattering form dust are fully considered. The inner radii measured are consistent with the expected dust sublimation radii. Modelling of AK Sco suggests a likely coplanarity between the disk and the binary's orbital planeComment: 19 pages, 11 figure

Phase Referencing in Optical Interferometry

One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce images. Such techniques allow only to achieve modest dynamic ranges. However, with high contrast objects, for faint targets or when structure detail is needed, phase referencing techniques as used in radio interferometry, should theoretically achieve higher dynamic ranges for the same number of telescopes. Our approach is not to provide evidence either for or against the hypothesis that phase referenced imaging gives better dynamic range than closure phase imaging. Instead we wish to explore the potential of this technique for future optical interferometry and also because image reconstruction in the optical using phase referencing techniques has only been performed with limited success. We have generated simulated, noisy, complex visibility data, analogous to the signal produced in radio interferometers, using the VLTI as a template. We proceeded with image reconstruction using the radio image reconstruction algorithms contained in AIPS IMAGR (CLEAN algorithm). Our results show that image reconstruction is successful in most of our science cases, yielding images with a 4 milliarcsecond resolution in K band. (abridged)Comment: 11 pages, 36 figure

Azoospermie non obstructive : auto-immunité, génétique, histologie testiculaire et résultats d’une prise en charge endocrinienne dans une série prospective de 29 patients

peer reviewedIntroduction : L’azoospermie non obstructive (NOA) est l’absence de spermatozoïdes dans l’éjaculat, secondaire à une anomalie de la spermatogenèse. L’étiologie de cette atteinte est souvent méconnue. Patients et Méthodes : Depuis 2020, nous suivons une série de 29 hommes( (32 ans) avec NOA, consultant pour une infertilité primaire. Ils ont bénéficié d’un bilan endocrinien et urologique, incluant une échographie testiculaire, un spermogramme, une bactériologie et une sérologie virales. Une première étude du caryotype, CFTR et micro délétions AZF(29 patients) a été suivie d’un panel de 130 gènes d’hypogonadisme (10 patients). Résultats : Une auto-immunité thyroïdienne a été retrouvée chez 14/29. Des anomalies génétiques sont présentes chez 11/29 cas incluant : XXY (1cas), délétion AZF (2cas), CFTR (2 cas), une mutation hétérozygote connexine 30-26, associant une surdité congénitale (1 cas), 2 mutations non décrites du récepteur aux androgènes, une mutation SRD5A2, maladie de Wilson (1cas), CYP21A2 (1cas). L’histologie testiculaire retrouve un arrêt de la spermatogenèse chez 11/14 cas et un Sertoli only syndrome chez 3/14 cas, avec une orchite localisée (auto-immune ?) chez 2 cas. Après stimulation de 3 à 6 mois par clomifène 50 mg/j (26 cas), létrozol 2.5mg/j (5 cas), et supplémentation par hydrocortisone (1 cas) ou lévothyroxine (13 cas), on observe à ce jour une faible production de spermatozoïdes chez 6/29 patients. Conclusions : L’auto-immunité et les causes génétiques incluant la voie des androgènes sont des mécanismes sous-estimés chez les patients avec NOA. Une prise en charge endocrinienne est susceptible d’améliorer la fertilité chez des patients soigneusement étudiés.Introduction: Non-obstructive azoospermia (NOA) is the absence of spermatozoa in the ejaculate, secondary to an abnormality of spermatogenesis. The etiology of this disease is often unknown. Patients and Methods: Since 2020, we followed a series of 29 men (with NOA, consultant for primary infertility). They underwent an endocrine and urological assessment, including testicular ultrasound, spermogram, bacteriology and viral serology. A first study of karyotype, CFTR and AZF microdeletions (29 patients) was followed by a panel of 130 hypogonadism genes (10 patients). Results: Thyroid autoimmunity was found in 14/29 patients. Genetic abnormalities were present in 11/29 cases including: XXY (1 case), AZF deletion (2 cases), CFTR (2 cases), a heterozygous connectin 30-26 mutation, associating congenital deafness (1 case), 2 undescribed androgen receptor mutations, an SRD5A2 mutation, Wilson's disease (1 case), CYP21A2 (1 case). Testicular histology showed arrest of spermatogenesis in 11/14 cases and Sertoli only syndrome in 3/14 cases, with localized orchitis (autoimmune?) in 2 cases. After stimulation of 3 to 6 months with clomiphene 50 mg/day (26 cases), letrozol 2.5 mg/day (5 cases), and supplementation with hydrocortisone (1 case) or levothyroxine (13 cases), low sperm production has been observed to date in 6/29 patients. Conclusions: Autoimmunity and genetic causes including the androgen pathway are underestimated mechanisms in patients with NOA. Endocrine management has the potential to improve fertility in patients who have been carefully studied

Impact of laser-assisted hatching on pregnancy rate in fresh and frozen-thawed cycles

peer reviewe

Oocyte Cryopreservation in Patients with Endometriosis: Current Knowledge and Number Needed to Treat.

peer reviewedThe rise of oocytes cryopreservation (OOC) in assisted reproductive techniques allows fertility preservation (FP) in an increasing number of indications. Endometriosis, a highly prevalent disease, potentially impairing ovarian reserve, seems, therefore, an interesting indication for it. The purpose of this study is to summarize the available evidence concerning FP by OOC in women with endometriosis and to calculate the number needed to treat (NNT). In total, 272 articles related to this topic were identified in PubMed. Eight studies were eligible for the review. In order to shed some light, a SWOT analysis was performed and the argument pros and cons were developed. The NNT calculated of OOC was 16, meaning that 16 women need to perform an OOC for one of them to have a child that she would not have had without this technique. In conclusion, OOC must be discussed with patients who suffer from endometriosis since it is an effective technique of FP, which can allow these patients to succeed a pregnancy that they otherwise would not have achieved. Nevertheless, it should not be performed in all patients as there is still a lack of robust socio-economic and risk-benefit data

Milli-arcsecond astrophysics with VSI, the VLTI spectro-imager in the ELT era

Nowadays, compact sources like surfaces of nearby stars, circumstellar environments of stars from early stages to the most evolved ones and surroundings of active galactic nuclei can be investigated at milli-arcsecond scales only with the VLT in its interferometric mode. We propose a spectro-imager, named VSI (VLTI spectro-imager), which is capable to probe these sources both over spatial and spectral scales in the near-infrared domain. This instrument will provide information complementary to what is obtained at the same time with ALMA at different wavelengths and the extreme large telescopes.Comment: 8 pages. To be published in the proceedings of the ESO workshop "Science with the VLT in the ELT Era", held in Garching (Germany) on 8-12 October 2007, A. Moorwood edito