3,969 research outputs found

    Reliability assessment of microgrid with renewable generation and prioritized loads

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    With the increase in awareness about the climate change, there has been a tremendous shift towards utilizing renewable energy sources (RES). In this regard, smart grid technologies have been presented to facilitate higher penetration of RES. Microgrids are the key components of the smart grids. Microgrids allow integration of various distributed energy resources (DER) such as the distributed generation (DGs) and energy storage systems (ESSs) into the distribution system and hence remove or delay the need for distribution expansion. One of the crucial requirements for utilities is to ensure that the system reliability is maintained with the inclusion of microgrid topology. Therefore, this paper evaluates the reliability of a microgrid containing prioritized loads and distributed RES through a hybrid analytical-simulation method. The stochasticity of RES introduces complexity to the reliability evaluation. The method takes into account the variability of RES through Monte- Carlo state sampling simulation. The results indicate the reliability enhancement of the overall system in the presence of the microgrid topology. In particular, the highest priority load has the largest improvement in the reliability indices. Furthermore, sensitivity analysis is performed to understand the effects of the failure of microgrid islanding in the case of a fault in the upstream network

    Study of a Strategy for Parallax Microlensing Detection Towards the Magellanic Clouds

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    In this article, we have investigated the possibility to distinguish between different galactic models through the microlensing parallax studies. We show that a systematic search for parallax effects can be done using the currently running alert systems and complementary photometric telescopes, to distinguish between different lens distance distributions. We have considered two galactic dark compact objects distributions, with total optical depths corresponding to the EROS current upper limits. These models correspond to two extreme hypothesis on a three component galactic structure made of a thin disc, a thick disc, and a spherically symmetric halo. Our study shows that for sub-solar mass lenses, an exposure of 8×1078\times 10^7 star×\timesyr toward LMC should allow to distinguish between these two extreme models. In addition the self-lensing hypothesis (lensing by LMC objects) can efficiently be tested through the method proposed here.Comment: 10 pages, 12 eps figures. To be published in A&A (accepted version). Minor changes: - Discussion added on the differential velocity of the thick galactic disk with respect to the thin disk. - Quality and lisibility of figures improved. - Typo errors correcte

    Osmo and hydro priming improvement germination characteristics and enzyme activity of Mountain Rye (Secale montanum) seeds under drought stress

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    Impacts of various concentrations of polyetylenglycol 6000 (PEG 6000)(0, -9, -11, -13 and -15 bar) and hydro priming on Mountain Rye (secale montanum) germination characteristic and enzyme activity were evaluated under drought stress in the seed laboratory of Natural Resources Faculty, University of Tehran, Karaj, Iran. Analyze of variance for hydro priming showed that temperature × time of priming interaction was significantly for germination percentage (GP), normal seedling percentage (NSP), coefficient of velocity of germination (CVG), seedling vigor index (SVI), coefficient of allometry (AC) and seedling length (SL) under drought stress and for osmo priming showed that Concentration of PEG × Temperature × Time of priming interaction was significantly for all traits under drought stress. Results of interaction effects for hydro priming showed that the highest GP (53%) and NSP (23.5%) were attained from hydro priming for 16h at 15 ◦C and the highest CVG (0.21) and AC (0.49) were attained from hydro priming for 8h at 10 ◦C, also hydro priming for 8h at 15 ◦C increased SL (3.15) as compared to the unprimed.Osmo priming with concentration of -15 bar PEG for 24h at 15 ◦C increased GP (80.5 %), GI (17.9), NSP (45 %), SVI (257.85) and SL (5.73 cm) and decreased MTG as compared to the unprimed and other treatments of osmo priming. The highest CVG was attained from concentration of -9 bar PEG for 24h at 10 ◦C. the highest AC was attained from concentration of -9 bar PEG for 12h at 15 ◦C. Also osmo and hydro priming increased catalase (CAT) and ascorbate peroxidase (APX) as compared to the unprimed

    Effect of Hormone Priming on Germination Characteristics and Enzyme Activity of Mountain Rye (Secale montanum) Seeds under Drought Stress Conditions

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    Seed priming techniques have been used to increase germination, improve germination uniformity and seedling establishment under stressed conditions. Seed priming was used in Rye Mountain (Secale montanum) to increase seed germination and tolerance on stress exposure. Rye seeds were treated with various priming agents for different time and temperatures. The effect of priming was assessed on germination characteristics on subsequent exposure to drought (PEG -14 bar) stress for 7 days. Seed priming treatments significantly (p≤ 0.01) affected, Germination percentage (GP), normality seedling percentage (NSP), germination Index (GI), germination uniformity (GU), means time to germination (MTG), coefficient of velocity of germination (CVG), seedling vigour index (SVI) and coefficient of allometry (AC). Seed priming with gibberelic acid (GA) and salicylic acid (SA) (p≤ 0.01) increased germination characteristics as the compared to the unprimed. Seed priming with concentrations 25, 50 ppm of GA for 15 h at 10 °C and 25 ppm of SA for 12 h at 10 °C, may be considered as optimal treatment for priming of Secale montanum seeds in drought stress conditions. Also priming increased catalase (CAT) and ascorbate peroxidase (APX) as compared to the unprimed

    The prevalence of domestic violence among pregnant women in Nigeria: a systematic review.

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    To identify, appraise, and synthesize research evidence on the prevalence of domestic violence (DV) among pregnant women in Nigeria. We conducted a systematic review of all published studies between April 2004 and June 2016. Comprehensive searches were conducted on electronic databases such as PubMed, CINAHL, Global Health, MEDLINE, PsycINFO, Directory of Open Access Journals, Google Scholar, and electronic libraries of the authors' institution. Identified articles were screened in two stages against the inclusion criteria with titles and abstract screened first followed by full-text screening. Selected articles were assessed using the "guidelines for evaluating prevalence studies," and findings were synthesized narratively. Among 19 studies that met the inclusion criteria, two articles were excluded due to low methodological quality and 17 articles were included in the review. The prevalence of DV during pregnancy in Nigeria ranged between 2.3% and 44.6% with lifetime prevalence rates ranging between 33.1% and 63.2%. Physical, sexual, psychological, and verbal abuses were the most frequent types of DV reported in this review. The most common perpetrators were husbands, as reported in 11 of the 17 studies. Pregnant women between the ages of 20 and 30 years were the most common victims of DV. Our review suggests high prevalence of DV in pregnancy among women in Nigeria and higher lifetime prevalence. However, determining an overall, synthesized accurate prevalence rate of DV within this population based on existing evidence presents a challenge. The findings have important implications for stakeholders such as planners, policy makers, maternity care providers, and researchers in public health and social policy at national, regional, and international levels toward combating the issue. OBJECTIVE METHOD RESULTS CONCLUSIO

    About the connection between the CC_{\ell} power spectrum of the Cosmic Microwave Background and the Γm\Gamma_{m} Fourier spectrum of rings on the sky

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    In this article we present and study a scaling law of the mΓmm\Gamma_m CMB Fourier spectrum on rings which allows us (i) to combine spectra corresponding to different colatitude angles (e.g. several detectors at the focal plane of a telescope), and (ii) to recover the ClC_l power spectrum once the Γm\Gamma_m coefficients have been measured. This recovery is performed numerically below the 1% level for colatitudes Θ>80\Theta> 80^\circ degrees. In addition, taking advantage of the smoothness of the ClC_l and of the Γm\Gamma_m, we provide analytical expressions which allow to recover one of the spectrum at the 1% level, the other one being known.Comment: 8 pages, 8 figure

    Estimation method for determining surface film conductance during cooling of fish packages.

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    This paper presents an alternative method for determining the surface film conductance of an infinite fish slab subjected to the cooling process. Many methods have been published, but their solutions have inherent appreciable inaccuracy and limitations. The present authors used the temperature histories of five locations within a slab sample of fish, obtained by the experimental investigation part of this work, along with the inverse heat conduction problem (IHCP) technique to develop a correlation for variable surface film conductance. When the above correlation was used for temperature predictions, the predicted and experimentally measured temperature distribution profiles were compared numerically. Better agreement than that implemented by other investigators was achieved. This revealed the accuracy and superiority of the present method, and the limitations of other methods are overcome in this method

    Observational Limits on Machos in the Galactic Halo

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    We present final results from the first phase of the EROS search for gravitational microlensing of stars in the Magellanic Clouds by unseen deflectors (machos: MAssive Compact Halo Objects). The search is sensitive to events with time scales between 15 minutes and 200 days corresponding to deflector masses in the range 1.e-7 to a few solar masses. Two events were observed that are compatible with microlensing by objects of mass of about 0.1 Mo. By comparing the results with the expected number of events for various models of the Galaxy, we conclude that machos in the mass range [1.e-7, 0.02] Mo make up less than 20% (95% C.L.) of the Halo dark matter.Comment: 4 pages, 3 Postscript figures, to be published in Astronomy & Astrophysic

    The EROS2 search for microlensing events towards the spiral arms: the complete seven season results

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    The EROS-2 project has been designed to search for microlensing events towards any dense stellar field. The densest parts of the Galactic spiral arms have been monitored to maximize the microlensing signal expected from the stars of the Galactic disk and bulge. 12.9 million stars have been monitored during 7 seasons towards 4 directions in the Galactic plane, away from the Galactic center. A total of 27 microlensing event candidates have been found. Estimates of the optical depths from the 22 best events are provided. A first order interpretation shows that simple Galactic models with a standard disk and an elongated bulge are in agreement with our observations. We find that the average microlensing optical depth towards the complete EROS-cataloged stars of the spiral arms is τˉ=0.51±.13×106\bar{\tau} =0.51\pm .13\times 10^{-6}, a number that is stable when the selection criteria are moderately varied. As the EROS catalog is almost complete up to IC=18.5I_C=18.5, the optical depth estimated for the sub-sample of bright target stars with IC<18.5I_C<18.5 (τˉ=0.39±>.11×106\bar{\tau}=0.39\pm >.11\times 10^{-6}) is easier to interpret. The set of microlensing events that we have observed is consistent with a simple Galactic model. A more precise interpretation would require either a better knowledge of the distance distribution of the target stars, or a simulation based on a Galactic model. For this purpose, we define and discuss the concept of optical depth for a given catalog or for a limiting magnitude.Comment: 22 pages submitted to Astronomy & Astrophysic

    The damping width of giant dipole resonances of cold and hot nuclei: a macroscopic model

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    A phenomenological macroscopic model of the Giant Dipole Resonance (GDR) damping width of cold- and hot-nuclei with ground-state spherical and near-spherical shapes is developed. The model is based on a generalized Fermi Liquid model which takes into account the nuclear surface dynamics. The temperature dependence of the GDR damping width is accounted for in terms of surface- and volume-components. Parameter-free expressions for the damping width and the effective deformation are obtained. The model is validated with GDR measurements of the following nuclides, 39,40^{39,40}K, 42^{42}Ca, 45^{45}Sc, 59,63^{59,63}Cu, 109120^{109-120}Sn,147^{147}Eu, 194^{194}Hg, and 208^{208}Pb, and is compared with the predictions of other models.Comment: 10 pages, 5 figure
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