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Ratios of glycerol dialkyl glycerol tetraethers (GDGT), which are membrane lipids of bacteria and archaea, are at the base of several paleoenvironmental proxies. They are frequently applied to soils as well as lake‐ and marine sediments to generate records of past temperature and soil pH. To derive meaningful environmental information from these reconstructions, high analytical reproducibility is required. Based on submitted results by 39 laboratories from across the world, which employ a diverse range of analytical and quantification methods, we explored the reproducibility of brGDGT‐based proxies (MBT′5ME, IR, and #ringstetra) measured on four soil samples and four soil lipid extracts. Correct identification and integration of 5‐ and 6‐methyl brGDGTs is a prerequisite for the robust calculation of proxy values, but this can be challenging as indicated by the large inter‐interlaboratory variation. The exclusion of statistical outliers improves the reproducibility, where the remaining uncertainty translates into a temperature offset from median proxy values of 0.3–0.9°C and a pH offset of 0.05–0.3. There is no apparent systematic impact of the extraction method and sample preparation steps on the brGDGT ratios. Although reported GDGT concentrations are generally consistent within laboratories, they vary greatly between laboratories. This large variability in brGDGT quantification may relate to variations in ionization efficiency or specific mass spectrometer settings possibly impacting the response of brGDGTs masses relative to that of the internal standard used. While ratio values of GDGT are generally comparable, quantities can currently not be compared between laboratories. Key Points: 39 laboratories participated in a round robin to determine the reproducibility of glycerol dialkyl glycerol tetraethers (GDGT) proxy values and quantitiesPeak selection impacts the ratio values and there is no apparent systematic impact of the extraction method and sample preparation stepsQuantification of GDGTs remains a problem, and comparison of GDGT concentrations between laboratories requires further method development [ABSTRACT FROM AUTHOR]

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The large number of distributed generators, storages, and other devices which might be connected to the distribution grid pose significant modelling and control questions. It is computationally unattractive and sometimes infeasible to model and control all these devices individually; some method of aggregating them both for modelling and for control is appealing so that they can be represented collectively. It would also be preferable to limit the complexity of the controlled devices' dynamic behavior for easy integration with higher‐level (i.e., higher‐authority) controllers in the cascade. This paper describes a method combining these control goals based on geometric flexibility regions, constrained optimization, and transfer function considerations to enforce approximated first‐order transfer function behaviour at the bus. Time‐domain simulations are used for validation and demonstration. [ABSTRACT FROM AUTHOR]

Abstract: Since the last century, several geological and geophysical studies have been developed in the Santiago Basin to understand its morphology and tectonic evolution. However, some uncertainties regarding sedimentary fill properties and possible density anomalies below the sediments/basement boundary remain. Considering that this is an area densely populated with more than 6 million inhabitants in a highly active seismotectonic environment, the physical properties of the Santiago Basin are important to study the geological and structural evolution of the Andean forearc and to characterize its seismic response and related seismic hazard. Two and three‐dimensional gravimetric models were developed, based on a database of 797 compiled and 883 newly acquired gravity stations. To produce a well‐constrained basement elevation model, a review of 499 wells and 30 transient electromagnetic soundings were used, which contribute with basement depth or minimum sedimentary thickness information. For the 2‐D modelling, a total of 49 gravimetric profiles were processed considering a homogeneous density contrast and independent regional trends. A strong positive gravity anomaly was observed in the centre of the basin, which complicated the modelling process but was carefully addressed with the available constrains. The resulting basement elevation models show complex basement geometry with, at least, eight recognizable depocenters with maximum sedimentary infill of ~ 500 m. The 3‐D density models show alignments in the basement that correlates well with important intrusive units of the Cenozoic and Mesozoic. Along with interpreted fault zones westwards and eastwards of the basin, the observations suggest a structural control of Santiago basin geometry, where recent deformation associated with the Andean contractional deformation front and old structures developed during the Cenozoic extension are superimposed to the variability of river erosion/deposition processes. [ABSTRACT FROM AUTHOR]

The design of efficient three‐phase induction motors is a challenge for engineering; therefore, new design techniques are continually being proposed. For example, efficiency is in conflict with manufacturing cost, which leads to the use of multi‐objective optimisation techniques to solve this engineering problem. Nevertheless, this study shows that the way of accurately modelling the behaviour of the motor is as important as the optimisation method itself. Thus, the study discusses fundamental considerations in the motor model as part of a proposed methodology for the design of highly efficient three‐phase squirrel cage induction motors. For this purpose, the motor is modelled in two ways: an analytical equivalent circuit and the finite element method, which are validated with data obtained from laboratory tests. The main contribution of this study is to show for the first time the required characteristics of the analytical model used as part of a multi‐objective optimisation problem to have a suitable accuracy with a competitive runtime. Moreover, the problem is solved using three bio‐inspired optimisation algorithms: non‐dominated sorting genetic algorithms II, non‐dominated sorting particle swarm optimisation and bacterial chemotaxis multi‐objective optimisation algorithm. The methodology is tested in the optimal redesign of a two‐pole, 3.7 kW, IE2 efficiency motor, for which the efficiency and cost were improved. [ABSTRACT FROM AUTHOR]

Recent works of different authors have shown that the use of intercell transformers in interleaved inverters bring many improvements to this kind of parallelism. However, even though a balanced current distribution is necessary and not guaranteed by the converter itself; just a few of those studies are focused on the modelling and control of the inverter. Moreover, the fact that the paralleled modules are coupled and that the control signals are not updated simultaneously have not been considered yet. In this way, the current paper takes those facts into account and proposes a simple procedure for modelling and control a single-phase interleaved inverter. A mathematical analysis, some simulation and experimental results are shown in order to prove the simplicity and effectiveness of the proposed procedure. [ABSTRACT FROM AUTHOR]

ABSTRACT We investigated whether stand structure modulates the long-term physiological performance and growth of Pinus halepensis Mill. in a semiarid Mediterranean ecosystem. Tree radial growth and carbon and oxygen stable isotope composition of latewood ( δ13CLW and δ18OLW, respectively) from 1967 to 2007 were measured in P. halepensis trees from two sharply contrasting stand types: open woodlands with widely scattered trees versus dense afforested stands. In both stand types, tree radial growth, δ13CLW and δ18OLW were strongly correlated with annual rainfall, thus indicating that tree performance in this semiarid environment is largely determined by inter-annual changes in water availability. However, trees in dense afforested stands showed consistently higher δ18OLW and similar δ13CLW values compared with those in neighbouring open woodlands, indicating lower stomatal conductance and photosynthesis rates in the former, but little difference in water use efficiency between stand types. Trees in dense afforested stands were more water stressed and showed lower radial growth, overall suggesting greater vulnerability to drought and climate aridification compared with trees in open woodlands. In this semiarid ecosystem, the negative impacts of intense inter-tree competition for water on P. halepensis performance clearly outweigh potential benefits derived from enhanced infiltration and reduced run-off losses in dense afforested stands. [ABSTRACT FROM AUTHOR]