Method of Equivalencing for a Large Wind Power Plant with Multiple Turbine Representation: Preprint

This paper focuses on our effort to develop an equivalent representation of a Wind Power Plant collector system for power system planning studies

New archaeointensity data from Italy and geomagnetic field intensity variation in the Italian Peninsula

We present new archaeointensity results from three Italian kilns situated at Ascoli Satriano, Vagnari and Fontanetto Po obtained with the Thellier modified by Coe double heating method. These data complement the directional results previously published. All sites are dated on the basis of archaeological information and/or thermoluminescence dating. The results are corrected for the anisotropy of the thermoremanent magnetization and the cooling rate effects. The new data are compared with previously published archaeointensity data from Italy and nearby countries within 900 km radius from Viterbo. An initial data set including archaeointesity data mainly coming from Italy, France, Switzerland, Czech Republic, Slovakia, Hungary, Greece and Bulgaria has been compiled. After the application of strict selection criteria, the most reliable data have been used for the calculation of a preliminary Italian intensity secular variation (SV) curve for the last 3000 yr. The new curve covers the 300 BC–400 AD and 1200–1900 AD periods. It is established by means of sliding windows of 200 yr shifted by 100 yr. The lack of reliable data for the 1000–200 BC and 400–1200 AD time intervals does not permit the calculation of a continuous curve. Clearly, more high-quality archaeointensity data from Italy and Europe are still needed to draw a robust intensity SV curve for the Italian Peninsula that could be used for archaeomagnetic dating in combination with the directional data

A comparison of Thellier-type and multispecimen paleointensity determinations on Pleistocene and historical lava flows from Lanzarote (Canary Islands, Spain)

Sixteen Miocene, Pleistocene, and historic lava flows have been sampled in Lanzarote (Canary Islands) for paleointensity analysis with both the Coe and multispecimen methods. Besides obtaining new data, the main goal of the study was the comparison of paleointensity results determined with two different techniques. Characteristic Remanent Magnetization (ChRM) directions were obtained in 15 flows, and 12 were chosen for paleointensity determination. In Thellier-type experiments, a selection of reliable paleointensity determinations (43 of 78 studied samples) was performed using sets of criteria of different stringency, trying to relate the quality of results to the strictness of the chosen criteria. Uncorrected and fraction and domain-state corrected multispecimen paleointensity results were obtained in all flows. Results with the Coe method on historical flows either agree with the expected values or show moderately lower ones, but multispecimen determinations display a large deviation from the expected result in one case. No relation can be detected between correct or anomalous results and paleointensity determination quality or rock-magnetic properties. However, results on historical flows suggest that agreement between both methods could be a good indicator of correct determinations. Comparison of results obtained with both methods on seven Pleistocene flows yields an excellent agreement in four and disagreements in three cases. Pleistocene determinations were only accepted if either results from both methods agreed or a result was based on a sufficiently large number (n>4) of individual Thellier-type determinations. In most Pleistocene flows, a VADM around 5 31022 Am2 was observed, although two flows displayed higher values around 931022 Am2.project CGL2012-32149 (Ministerio de Econom ıa y Competitividad, Spain), project 320/2011 (Ministerio de Medio Ambiente y Medio Rural y Marino, Spain) and the European Regional Development Fund (ERDF)

Further progress in the study of epsilon iron oxide in archaeological baked clays

The occurrence of ε-Fe2O3 in archaeological samples that have been subjected to high temperatures is gradually being detected by the use of micrometric structural characterization techniques. This work provides new information by revealing that the ε-Fe2O3 is formed as a response to temperature, the aggregation state and the position within the baked clay with respect to the nearest heat source. In addition, depending mainly on the atmospheric environment, the temperature reached by the combustion structure, the distance from the heating source and the particle aggregation, other iron oxide magnetic phases are produced. In the baked clay studied here, hematite is found over the whole range of samples studied but its magnetic contribution is negligible. Magnetite is observed at the sample surface, probably due to local atmospheric environment closest to the combustion source. Maghemite is found at all depths up to 6 cm below the sample surface. ε-Fe2O3 has a limited distribution, found within 2–3 cm of the sample surface. Furthermore, the viability of this compound as a palaeofield marker has been evaluated in both archaeological and synthetic samples. The results indicate that ε-Fe2O3 is able to register the direction of the magnetic field. Linear palaeointensity plots have been obtained in synthetic samples, although the value of the palaeofield could be, sometimes, overestimated

Magnetic Granulometry and Mössbauer Spectroscopy of Synthetic Fe<inf>m</inf>O<inf>n</inf>-TiO<inf>2</inf> Composites

© 2020 IEEE. FemOn-TiO2 particle aggregates have been obtained using the sol-gel method and hydrothermal treatment. It is shown that the synthesis conditions favor forming composites that contain titanomagnetite in very low concentrations. Hysteresis loops and demagnetization curves of anhysteretic remanent magnetization were measured with a vibration sample and a SQUID magnetometer, respectively. Mössbauer spectroscopy, bulk magnetic properties, scanning electron microscopy (SEM) observations, coupled with the theoretical analysis of magnetostatic interaction between finely dispersed particles lead to a conclusion that the studied composites can be viewed as groups of interacting clusters 2-20 μm in size, consisting of chemically heterogeneous, mostly single-domain or close to single-domain particles with an average size of about 100 nm

Magnetic characterization of the Daule chondrite (Ecuador\u27s first meteorite fall): The case of elusive tetrataenite?

We investigated the magnetic properties of Ecuador\u27s first reported meteorite fall (March 23, 2008), the Daule ordinary chondrite (L5, S4, W0) using thermomagnetic analyses at high and cryogenic temperatures, analyses of magnetic hysteresis and first-order reversal curves, and thermal and alternating field (AF) demagnetization of natural remanent magnetization (NRM). The mineralogical and chemical composition of Daule was examined using scanning electron microscopy with energy-dispersive x-ray spectroscopy. Most methods indicate that the magnetic properties of Daule are dominated by multidomain FeNi alloys (kamacite) with Ni content varying between ∼4% and ∼17%. However, backfield demagnetization (BFD) analyses revealed the presence of high-coercivity tetrataenite that survived shock metamorphism. The differential survival of tetrataenite at the millimeter scale indicates heterogeneity of the impact-related temperature and pressure fields within the Daule meteorite. BFD curves may serve as an efficient tool for identifying minor amounts of tetrataenite that otherwise cannot be discerned from the signal from magnetically-soft FeNi mineral phases by methods based on induced magnetization. Thermal demagnetization experiments unveiled the presence of a well-defined characteristic component of NRM, which remains resistant to AF demagnetization. We interpret this component as a pre-impact thermochemical remanence carried by tetrataenite and acquired during the thermal metamorphism of the parent body. At cryogenic temperatures, the magnetic properties of Daule are dominated by low-Mg magnesiochromite with the Curie temperature at 60–70 K