1,721,005 research outputs found
Experimental evaluation of the limit condition for tap-staggered autotransformers through noise and vibration analysis
No full textThe growing demand for electric energy and the development of green sources such as photovoltaic and wind power are requiring the integration of new systems in the already developed transmission network. This task is not always straightforward, since when a large amount of power is not used, it gives rise to reactive loads. Usually, to put back into phase the voltage and the current, specific devices such as reactors are applied at the electric station level. One of the practices that are becoming increasingly common is the use of two autotransformers adopting the tap-staggering technique. In this way, already existing devices can be used to rearrange the electric line parameters. One of the downsides is that, related to the specific design of the transformers, high magnetic flux can occur in the core. Due to overexcitation, vibrations generated by magnetostriction can become extremely high and can bring to damages that in some cases can cause an impairment of the device. This article aims to find suitable parameters able to predict the approaching of a limit condition beyond which the autotransformer can undergo damage. For this purpose, experimental investigations considering the vibrations and the noise emitted by five autotransformers were carried out in different tap staggering conditions. It was found that the acceleration values very much depend on the position of the transducer, while the acoustic noise measurements give an average of the sound radiated by the different parts of the autotransformers but depend on the distance from the case of the device. For this reason, it is advised not to exceed an average overall value of 80 dB(A) sound pressure level at a 2 m distance from the autotransformer
Design of sound insulating sandwich structures based on multiple criteria
No full textThe pressure on the electric power grid deriving from the growing use of renewable sources and mobility electrification is pushing new infrastructures closer to the urban environment. For this reason, the equipment must be as quiet as possible or otherwise enclosed in technical volumes having the functions to prevent unauthorised access and shield the noise propagating towards the neighbourhood. The different nature of the noise generated by the equipment, together with the other conditions that influence the propagation towards the receivers, require the choice of panels which may differ case by case. For this reason an ad-hoc optimization of the internal structure of the panels may be needed. This article proposes a procedure allowing the selection of the best sandwich structure able to contain the noise on the base of some characteristics such as the weight, the maximum thickness, the cost and the environmental sustainability
Dipotassium glycyrrhizate via HMGB1 or AMPK signaling suppresses oxidative stress during intestinal inflammation
No full textAims Oxidative stress and inflammation are always associated. Appropriate management of oxidative mediators may represent a therapeutic strategy to reduce inflammation, and use of antioxidant can be protective against inflammatory diseases. Glycyrrhizin (GL) plays an anti-inflammatory and antioxidant effect by inhibiting high mobility group box 1 (HMGB1) or 11-β-hydroxysteroid dehydrogenase type II (11βHSD2) enzyme. In this study, the potential role of dipotassium glycyrrhizate (DPG), a salt of GL, to reduce oxidative stress in intestinal inflammatory condition was investigated in vivo and the mechanism of action of DPG was studied in vitro. Results In a colitis mouse model DPG affected oxidative stress reducing iNOS and COX-2 expression, as well as NO and PGE2 levels. By means of LPS-stimulated macrophages we found that DPG inhibited the expression of pro-inflammatory cytokines and reduced iNOS and COX-2 expression in a time dependent manner, through two different ways of signal. DPG reduced, at a later time, both iNOS and COX-2, through a mechanism HMGB1-dependent, and at an earlier time only COX-2, through a mechanism AMP-activated kinase (AMPK)-phosphorylation-mediated. Conclusion DPG has a protective effect on colitis and inflammation through the inhibition of oxidative stress. This study clarifies the two-ways mechanism by which DPG inhibits iNOS and COX-2 during inflammation and demonstrates for the first time that AMPK is a target of DPG. Uncovering this mechanism is significant to clarify the relationship between energy homeostasis and anti-oxidative responses and suggests that DPG could play a relevant role in the development of new therapy against inflammatory diseases associated to oxidative stress. © 2015 Elsevier Inc. All rights reserved
Dipotassium Glycyrrhizate Inhibits HMGB1-Dependent Inflammation and Ameliorates Colitis in Mice
No full textBackground:High mobility group box-1 (HMGB1) is a DNA-binding protein that is released from injured cells during inflammation. Advances in targeting HMGB1 represent a major challenge to improve the treatment of acute/chronic inflammation.Aim:This study is aimed at verifying whether the inhibition of HMGB1 through dipotassium glycyrrhizate (DPG) is a good strategy to reduce intestinal inflammation.Methods:Human colon adenocarcinoma cell line, HT29, human epithelial colorectal adenocarcinoma, Caco2, and murine macrophage cell line, RAW 264.7, were cultured to investigate the effect of DPG on the secretion of HMGB1. Acute colitis was induced in C57BL/6 mice through administration of 3% dextran sodium sulphate (DSS); a combined treatment with DSS and 3 or 8 mg/kg/day DPG was used to investigate the effects of DPG on intestinal inflammation. Animals were euthanized at seventh day and colonic samples underwent molecular and histological analyses.Results:DPG significantly reduces in vitro the release of HMGB1 in the extracellular matrix as well as expression levels of pro-inflammatory cytokines, TNF-alpha, IL-1beta and IL-6, by inhibiting HMGB1. Moreover, DPG significantly decreases the severity of DSS-induced colitis in mice. Murine colonic samples show decreased mRNA levels of pro-inflammatory cytokines TNF-alpha, IL-1beta and IL-6, as well as HMGB1 receptors, RAGE and TLR4. Finally, HMGB1, abundantly present in the feces of mice with DSS-induced colitis, is strongly reduced by DPG.Conclusions:HMGB1 is an early pro-inflammatory cytokine and an active protagonist of mucosal gut inflammation. DPG exerts inhibitory effects against HMGB1 activity, significantly reducing intestinal inflammation. Thus, we reason that DPG could represent an innovative tool for the management of human intestinal inflammation. © 2013 Vitali et al
Sodium-nickel chloride battery experimental transient modelling for energy stationary storage
No full textThe paper presents the analysis of Sodium Nickel chloride batteries in transient operation, and proposes a simple but very precise model to represent both the transient and steady battery behaviours. Hence, the main purpose of this model is to foresee the battery voltage during the most important network services, which require very fast transitions from the battery charge operation to the discharge one. In order to validate the model, several comparisons between experimental measures and model results are shown
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Cost evaluation of EHVAC offshore wind farm interconnections using intermediate shunt compensation: A parametric study
No full textA double-circuit line using commercially available 400 kV-50 Hz three-core XLPE-insulated submarine cables is considered for the evacuation of up to 1 GW offshore wind generation. Three transmission distances are studied, namely 80 km, 100 km and 160 km, evaluating conventional (line-end) as well as mid-line shunt compensation. Operating envelopes and transmission losses are assessed, showing the low losses at EHVAC cable transmission and the beneficial effects of midline compensation, which allows covering distances up to 180 km. Results show that the proposed transmission solution guarantees very low full-load losses, not exceeding 1.5%, 2% and 3% for the simulated cases. Lastly, a technical-economic comparison based on Dutch North Sea wind producibility data and new German feed-in tariffs, is subsequently carried out in order to assess the capitalized losses of the different EHVAC solutions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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