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AbstractAlumosilicate minerals are suitable sorbents at high temperatures for removing alkalis in syngas. Thermogravimetric investigations of these sorbents usually focus on the reaction mechanisms. Herein, a crucible arrangement is described that allows evaporation of the alkali source and sorption of gaseous alkali components in one temperature zone. With this experimental setup, kinetic investigations of alkali sorption are possible in a conventional thermobalance. Experiments were performed with sodium chloride as the alkali source and kaolin as the getter material. The reaction rate increased with alkali concentration and showed an exponential dependence on temperature. Thus, the Arrhenius model approach and power law model were selected for mathematical description.

AbstractThe rotational spectra of two isotopologues of the 1:1 complex formed between acetone and ethanol have been recorded and analyzed by using Fourier‐transform microwave spectroscopy. One rotamer was detected, in which ethanol adopts the gauche form. The two subunits are linked by a conventional O−H⋅⋅⋅O and a weak C−H⋅⋅⋅O hydrogen bond, forming a six‐membered ring. Each rotational transition is split into five component lines due to the internal rotations of two nonequivalent acetone methyl groups. The V3 barriers to internal rotation of the two CH3 tops of acetone were determined to be 252(4) and 220(1) cm−1, which are noticeably lower than the value for the monomer (266 cm−1).

IntroductionBoth mean power output (MPO) and the distribution of the available energy over the race, that is, pacing strategy, are critical factors in performance. The purpose of this study was to determine the relative importance of both pacing strategy and MPO to performance.MethodsSix well-trained, regionally competitive cyclists performed four 1500-m ergometer time trials (∼2 min). For each subject, the fastest (Fast) and slowest (Slow) time trials were compared and the relative importance of differences in power output and pacing strategy were determined with an energy flow model.ResultsThe difference in final time between Fast and Slow was 4.0 (2.5) s. Fast was performed with a higher MPO (437.8 (32.3) W vs 411.3 (39.0) W), a higher aerobic peak power (295.3 (36.8) vs 287.5 (34.7) W) and a higher anaerobic peak power (828.8 (145.4) W vs 649.5 (112.2) W) combined with a relatively higher, but not statistically different anaerobic rate constant (0.051 (0.016) vs 0.041 (0.009) W). The changes in MPO (63% anaerobic, 37% aerobic) largely explained the differences in final times. Athletes chose a different pacing strategy that was close to optimal for their physiological condition in both Fast and Slow.ConclusionDifferences in intraindividual performance were mainly caused by differences in MPO. Athletes seemed to be able to effectively adjust their pacing profile based on their “status of the day”.Keywordsmodelling performance, energy expenditure, aerobic, anaerobic, sports.

Silica-tin dioxide thin films doped with Er3+ ions were fabricated and investigated. Different parameters such as heat-treatment temperatures, molar concentrations of SnO2 as well as Er3+ ions concentration were changed in order to obtain the best properties of presented thin films. Using several techniques, thin films were characterized and proved to be crack-free, water-free and smooth after a heat-treatment at 1200 °C. Aiming to application in optics, the transparency of thin films was also evidenced by transmission spectra. Based on the photoluminescence measurements, the mechanism of energy transfer from SnO2 nanocrystals to Er3+ ions was examined and discussed.

Thin film technology has reached a maturity to achieve conversion efficiencies of the order of 22%. Among thin films, CdTe-based photovoltaic modules represent 80% of the total production. Nonetheless, some issues concerning back-contact are still open. In industrial process a chemical etching is required in order to make the CdTe film surface rich in Te. The Te-excess is fundamental in order to form a stable telluride compound with copper and to obtain an ohmic, low-resistance back-contact. Moreover, the Te-excess hinders the fast diffusion of copper in CdTe and its achievement of the junction region, preventing the destruction of the device. In this paper we study a ZnTe:Cu buffer layer deposited onto a CdTe film, characterized by a naturally Te-rich surface obtained with a particular chlorine heat treatment without any chemical etching. Copper diffusion and the CdTe/ZnTe:Cu interface were studied by x-ray photoemission spectroscopy (SIPS) and time-of-flight secondary ion mass spectrometry (ToF- SIMS) to deeply analyze the intermixing phenomena and copper behavior inside polycrystalline CdTe film.

Storage capacity is a key aspect when validating potential CO2 sequestration sites. Most CO2 storage projects, for obvious reasons, target conventional aquifers (e.g., saline aquifers, depleted hydrocarbon fields) with good reservoir properties and ample subsurface data. However, non-geological factors, such as proximity to the CO2 source, may require storing CO2 in geologically “less-than-ideal” sites. We here present a first-order CO2 storage resource estimate of such an unconventional storage unit, a naturally fractured, compartmentalized and underpressured siliciclastic aquifer located at 670–1,000 m below Longyearbyen, Arctic Norway. Water injection tests confirm the injectivity of the reservoir. Capacity calculations, based on the US DOE guidelines for CO2 storage resource estimation, were implemented in a stochastic volumetric workflow. All available data were used to specify input parameters and their probability distributions. The areal extent of the compartmentalized reservoir is poorly constrained, encouraging a scenario-based approach. Other high-impact parameters influencing storage resource estimates include CO2 saturation, CO2 density and the storage efficiency factor. The hydrodynamic effects of storing CO2 in a compartmentalized aquifer are accounted for by calculating probable storage efficiency factors (0.04–0.79 %) in a fully closed system. The results are ultimately linked to the chosen scenario, with two orders of magnitude difference between scenarios. The fracture network contributes with up to 2 % to the final volumes. The derived workflow validates CO2 storage sites based on initial feasibility assessments, and may be applied to aid decision making at other unconventional CO2 storage sites with significant data uncertainty.

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.