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Capítulos en libros Dynamic Voltage Restorers (DVRs) are a costeffective solution to protect sensitive loads against voltage sags in medium- and high-power applications because the power required to compensate sags is only a fraction of the load rated power. Also, the energy storage requirements of DVRs can be greatly reduced by using minimum-power compensation of voltage sags. However, this compensation strategy can disturb sensitive loads and tends to saturate the injection transformer unless a slow phase rotation technique is used when a voltage sag is detected. The sag detection needs to be robust, but also fast to provide accurate results so that the DVR can work under all possible situations. This paper proposes and studies in detail a sag-detection algorithm for a DVR that, when designed and implemented carefully, provides excellent performance when the grid voltage contains harmonics and the grid frequency varies. All the algorithms proposed in this paper are tested on a 5 kVA prototype of a DVR. info:eu-repo/semantics/publishedVersion

Research and development of cost-effective, high-performance thermal insulation materials for the construction sector has to be focused on their final application. In particular, solutions for refurbishing historic buildings, which represent 40% of the European building stock, have to offer a good compromise between environmental quality, energy efficiency and conservation aspects. In this paper, the experimental assessment of an insulation material based on aerogel technology, recently developed in the European project EFFESUS, is presented with regard to the material's thermal performance, compatibility with historic fabric and reversibility. The overall results obtained in laboratory testing on a real-size mock-up and in a real-world case application indicate that the new material is a promising solution for retrofitting historic buildings, thanks to its thermal properties, easy application, reversibility and material compatibility.

To review new putative mechanisms involved in the pathophysiology of a disturbed energy balance in cancer cachexia, which can lead to novel targets for clinical cachexia management. In the context of rapid developments in tumour treatment with potential systemic consequences, this article reviews recent data on energy requirements. Furthermore, we focus on new insights in brown adipose tissue (BAT) activity and reward processing in the brain in relation to the cachexia process.Nearly no new data have been published on energy requirements of cancer patients in the light of comprehensive new therapies in oncology. New developments, such as the introduction of staging with 18F-fluorodeoxyglucose PET-computed tomography scanning, led to the observation that BAT activation may contribute to impaired energy balance in cancer cachexia. Animal and human data to date provide an indication that BAT activation indeed occurs, but its quantitative impact on the degree of cachexia is controversial. The peripheral and central nervous system is known to influence satiation, with a possible role for impaired food reward processing in the brain. To date, there are limited confirmatory data, but this is an interesting new area to explore for better understanding and treating cancer-induced anorexia.The multimodal approach to counteract cancer cachexia should expand its targets to BAT and food reward processing in the brain.

Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48 ± 0.18 petagrams of carbon per year (Pg C yr(-1)) during the dry year but was carbon neutral (0.06 ± 0.1 Pg C yr(-1)) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25 ± 0.14 Pg C yr(-1), which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39 ± 0.10 Pg C yr(-1) previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.

A series of samples are collected from the catholyte solution of a vanadium redox flow battery (VRFB) at different values of state of charge (SoC)/state of discharge (SoD). The samples are analyzed by means of Raman spectroscopy to identify: (i) the species present into the catholyte; and (ii) how the composition of the catholyte is modulated along the charge and discharge processes of the VRFB. Raman results reveal that the most abundant species in the catholye are VO2+ and VO2 +; they are coordinated by HSO4 - and SO4 2- ligands. During the charge process of the VRFB the equilibrium between the vanadium species is shifted towards the formation of an ensemble of V(V) complexes. Instead, during discharge a family of V(IV) species is obtained. The formation of concatenated HV2O5 - and H3V2O7 - species in the catholyte is revealed, which indicates that side electrochemical reactions occur during the charge and discharge processes of a VRFB. The presence of these side reactions plays a crucial role in the modulation of the Coulombic efficiency of the VRFB. This work highlights the complexity of the chemical situation at a VRFB cathode, and the great importance to understand/control such chemical situation to improve the performance of VRFBs in the scenario of electrochemical energy storage field

AbstractAimBats are promising candidates for studying morphometric responses to anthropogenic climate or land‐use changes. We assessed whether the cranial size of a common bat (Pipistrellus kuhlii) had changed between 1875 and 2007. We formulated the following hypotheses: (1) if heat loss is an important reaction to climate change, body size will have decreased in response to the increased temperatures, because small bats have a larger surface‐to‐volume ratio and dissipate heat more effectively; (2) if water loss is the main driver, body size will have increased in response to the temperature increase, because larger bats will lose water more slowly through a reduced surface‐to‐volume ratio; (3) the energetic benefits provided by urbanization (food concentration at street lamps, warmer maternity roosts in buildings) will lead to a general body size increase in P. kuhlii; and (4) because street lamps impair moth antipredatory manoeuvres, cranial size may have selectively increased as an adaptive response to handle larger prey (moths) in artificially illuminated sites. Ours is the first study to assess temporal trends in bat body size over more than a century and to relate them to urbanization.LocationMainland Italy.MethodsWe used traditional morphometrics to compare seven variables of skull size in 117 museum specimens (75 female, 42 male).ResultsCranial size increased after 1950, but this change was not paralleled by an increase in body size, measured as forearm length. This selective increase matched a rapid increase in electric public illumination in Italy.Main conclusionsStreet lights are crucial foraging sites for P. kuhlii. The directional change that we found in cranial size might represent microevolutionary adaptive tracking of a sudden shift in food size, making more profitable prey available.

This paper provides a focus upon forecasting electricity prices in the medium term (from a few weeks to several months ahead) in which accurate estimates of tail risks, e.g. at the 1%, 5%, 95% and 99%, are important. Medium term forecasting and risk analysis are important for operational scheduling, fuel purchasing, trading and profit management. We extend the research on hybrid forecasting methods, which link detailed fundamental price formation models, using optimization techniques and market equilibrium considerations, with econometric re-calibration to the time series data. This paper is innovative in its use of quantile regression to undertake the recalibration and provide accurate risk estimates. It is shown that probabilistic outputs from the fundamental model add value over expected value inputs to the quantile regressions and that if the fundamental model is itself well-specified to diurnal variation through the inclusion of relevant explanatory variables such as demand or climatic conditions, then it is not necessary to undertake the quantile regressions separately for each hour of the day. A real application of the proposed methodology is successfully tested on the Spanish electric power system, in which the high penetration of intermittent wind generation creates extreme price risks. The hybrid method outperforms the more conventional fundamental model, making particular use of wind generation data in the quantile re-calibrations. info:eu-repo/semantics/draft

A consequence of Darwin's 'principle of divergence' is that loss of species can harm the functioning of ecosystems. A study of algal communities in artificial streams suggests that he was right. See Letter p.86 Studies in recent years have suggested that the conservation of biodiversity improves the ability of an ecosystem to retain nutrients and remain productive. These papers have proved controversial, in part because of a lack of direct evidence for a mechanism to explain the phenomenon. Now, in experiments involving manipulation of the number of algal species in model stream systems, Bradley Cardinale provides one such mechanism. Uptake of nitrogen nutrients increased linearly with species richness in response to changes in flow habitats and disturbance regimes. But when niche structure was experimentally removed, the relationship disappeared. This suggests that habitats with more species take greater advantage of the niche opportunities in an environment than do less-species-rich habitats, allowing the more diverse systems to capture a greater fraction of biologically active resources such as nitrogen.