ALBERT

Description: New magnetostratigraphic results from a 3300 m-thick section across the syntectonic fluvial sediments of the Campodarbe Formation (Upper Eocene–Oligocene) in the Ebro foreland basin (NE Spain) are presented. The new data allow the top of the Campodarbe Formation to be correlated to Chron 7r (Chattian), younger than previously stated (C10r), therefore shifting the age of significant palaeogeographical changes in the foreland basin. The deformation in the southern front produces the cannibalization in the piggyback basin of 1300 m of sediments spanning c. 3.7 Myr. Average accumulation rates are lower in the Ebro foreland basin than in the piggyback basin and decrease from 35 to 27 cm kyr –1 by the time the San Felices thrust sheet activity decelerates (at c. 28 Myr). Shifts of accumulation rates result from accommodation space changes, which occur locally and are linked to the activity of the San Felices thrust, while the sediment supply occurs at orogenic scale (source of sediments is c. 200 km to the NE). Finally, sequence boundaries previously considered isochronous in the continental record of the Cenozoic Pyrenean basins are revealed to be 1.8–1 Myr older in the piggyback basin than in the Ebro foreland basin.

Description: Stand-alone power systems based on renewable energy sources are used to replace generators based on fossil fuels. Those renewable power systems also require Energy Storage Devices (ESD) interfaced by a charger/discharger power converter, which consist of a bidirectional DC/DC converter, and a DC bus. This paper proposes a single sliding-mode controller (SMC) for the charger/discharger DC/DC converter to provide a stable DC bus voltage in any operation condition: charging or discharging the ESD, or even without any power exchange between the ESD and the DC bus. Due to the non-linear nature of the power converter, the SMC parameters are adapted on-line to ensure global stability in any operation condition. Such stability of the adaptive SMC is mathematically demonstrated using analytical expressions for the transversality, reachability and equivalent control conditions. Moreover, a design procedure for the adaptive SMC parameters is provided in order to ensure the dynamic response required for the correct operation of the load. Finally, simulations and experimental tests validate the proposed controller and design procedure.

Description: The Cotiella thrust sheet in the South Central Pyrenees is a well-studied example of an extensional basin that formed at the northern Iberian rift margin during the Late Cretaceous, and was inverted in the Late Cretaceous and Cenozoic on top of the South Pyrenean Central Unit. A palaeomagnetic study of the thick sequence of shallow marine syn-extensional carbonates filling the Cotiella Basin reveals the presence of a widespread secondary magnetization of both normal and reversed polarities. Neither in situ nor bedding tilt correction provides a satisfactory grouping of the palaeomagnetic directions, thus suggesting syn-deformational magnetization. Best clustering of palaeomagnetic vectors is obtained after unfolding into a post-extensional pre-compressional stage, coherent with an acquisition age between Santonian and Paleocene. Strong magnetic enhancement and very distinct magnetic properties with depth suggest a link with burial diagenesis of organic matter, precipitation of iron sulphides and subsequent oxidation to SD fine-grained magnetite. The secondary magnetizations of the Cotiella record significant vertical axis rotations ranging from 14° to 52° clockwise, coherent with the scenario of the Cotiella thrust sheet transported piggy-back and bent during the emplacement of the lower Gavarnie–Sierras Exteriores thrust sheet.

Description: A recent approach to mitigate the adverse effects of photovoltaic (PV) arrays operating under mismatching conditions is the dynamic electrical reconfiguration of the PV panels. This paper introduces a procedure to determine the best configuration of a PV array connected in a series-parallel structure without using complex mathematical models. Such a procedure uses the experimental current vs. voltage curves of the PV panels, which are composed of multiple PV modules, to construct the power vs. voltage curves of all of the possible configurations to identify the optimal one. The main advantage of this method is the low computational effort required to reconstruct the power vs. voltage curves of the array. This characteristic enables one to implement the proposed solution using inexpensive embedded devices, which are widely adopted in industrial applications. The proposed method, and its embedded implementation, were tested using a hardware-in-the-loop simulation of the PV system. Finally, the real-time operation and benefits of the proposed solution are illustrated using a practical example based on commercial devices.

Description: ABSTRACT We present a source-to-sink environmental magnetic study of a sediment core from Lake Sanabria (north-west Iberian Peninsula) and rocks of its catchment. The results indicate the occurrence of magnetite, and probably also pyrrhotite, in sediments accumulated between ca. 26 and 13 cal ka BP in a proglacial lake environment. These minerals also appear to dominate the magnetic assemblage of Palaeozoic rocks from the lake catchment. This indicates that sedimentation was then driven by the erosion of glacial flour, which suffered minimal chemical transformation due to a rapid and short routing to the lake. A sharp change in magnetic properties observed in the lake sediments between 13 and 12.6 cal ka BP reflects the rapid retreat of glaciers from the lake catchment. Sediments from the upper half of the studied sequence, accumulated after 12.6 cal ka BP in a lacustrine environment with strong fluvial influence, contain magnetite and smaller amounts of maghemite and greigite. We suggest that greigite grew authigenically under anoxic conditions caused by enhanced accumulation of organic matter into the lake. The occurrence of maghemite in these sediments suggests pedogenic activity in the then deglaciated lake catchment before the erosion and transportation of detrital material into the lake.

Description: A previous article has presented the members of the asymmetrical interleaved dc/dc switching converters family as very appropriate candidates to interface between photovoltaic or fuel cell generators and their loads because of their reduced ripple and increased current processing capabilities. After a review of the main modeling methods suitable for high-order converters operating, as the asymmetrical interleaved converters (AIC) ones, in discontinuous current conduction mode a full-order averaged model has been adapted and improved to describe the dynamic behavior of AIC. The excellent agreement between the mathematical model predictions, the switched simulations and the experimental results has allowed for satisfactory design of a linear-quadratic regulator (LQR) in a fuel-cell application example, which demonstrates the usefulness of the improved control-oriented modeling approach when the switching converters operate in discontinuous conduction mode.

Description: A fifth-order dynamic continuous model of a linear induction motor (LIM), without considering “end effects” and considering attraction force, was developed. The attraction force is necessary in considering the dynamic analysis of the mechanically loaded linear induction motor. To obtain the circuit parameters of the LIM, a physical system was implemented in the laboratory with a Rapid Prototype System. The model was created by modifying the traditional three-phase model of a Y-connected rotary induction motor in a d–q stationary reference frame. The discrete-time LIM model was obtained through the continuous time model solution for its application in simulations or computational solutions in order to analyze nonlinear behaviors and for use in discrete time control systems. To obtain the solution, the continuous time model was divided into a current-fed linear induction motor third-order model, where the current inputs were considered as pseudo-inputs, and a second-order subsystem that only models the currents of the primary with voltages as inputs. For the discrete time model, the current-fed model is discretized by solving a set of differential equations, and the subsystem is discretized by a first-order Taylor series. Finally, a comparison of the continuous and discrete time model behaviors was shown graphically in order to validate the discrete time model.

Description: Energies, Vol. 11, Pages 1082: Modelling, Analysis and Performance Evaluation of Power Conversion Unit in G2V/V2G Application—A Review Energies doi: 10.3390/en11051082 Authors: María Garcés Quílez Mohamed Abdel-Monem Mohamed El Baghdadi Yang Yang Joeri Van Mierlo Omar Hegazy In response to climate change, which is caused by the increasing pollution of the environment and leads to the deterioration of human health, future electricity generations should reduce reliance on fossil fuels by growing the use of clean and renewable energy generation sources and by using clean vehicle technologies. Battery storage systems have been recognized as one of the most promising approaches for supporting the renewable energy generation sources and cleanly powering vehicles instead of burning gasoline and diesel fuel. However, the cost of batteries is still a prominent barrier for their use in stationary and traction applications. As a rule, the cost of batteries can be decreased by lowering material costs, enhancing process efficiencies, and increasing production volume. Another more effective solution is called Vehicle-to-grid (V2G) application. In V2G application, the battery system can be used to support the grid services, whereas the battery is still in the vehicle. To make a battery system economically viable for V2G/G2V applications, an effective power-electronics converter should be selected as well. This converter should be supported by an advanced control strategy. Therefore, this article provides a detailed technical assessment and review of V2G/G2V concepts, in conjunction with various power-electronics converter topologies. In this paper, modeling and detailed control strategies are fully designed and investigated in terms of dynamic response and harmonics. Furthermore, an extensive design and analysis of charging systems for low-duty/high-duty vehicles are also presented.

Description: Energies, Vol. 10, Pages 1316: Maximum Power Point Tracking of Photovoltaic Panels by Using Improved Pattern Search Methods Energies doi: 10.3390/en10091316 Authors: Andrés Tobón Julián Peláez-Restrepo Juan Villegas-Ceballos Sergio Serna-Garcés Jorge Herrera Asier Ibeas This paper deals with the optimization of maximum power point tracking when a photovoltaic panel is modelled as two diodes. The adopted control is implemented using a sliding mode control (SMC) and the optimization is implemented using an improved Pattern Search Method. Thus, the problem of maximum power point tracking is reduced to an optimization problem whose solution is implemented by Pattern Search Techniques, inheriting their convergence properties. Simulation examples show the effectiveness of the proposed technique in practice, being able to deal with different radiations. In addition, improved pattern search method (IPSM) is compared with other techniques such as perturb & observe and Particle Swarm optimization, after which IPSM presents lower energy losses in comparison with the other two algorithms, with the advantage of ensuring the location of the optimal power point in all cases.

Description: New magnetostratigraphic results from a 3300 m-thick section across the syntectonic fluvial sediments of the Campodarbe Formation (Upper Eocene–Oligocene) in the Ebro foreland basin (NE Spain) are presented. The new data allow the top of the Campodarbe Formation to be correlated to Chron 7r (Chattian), younger than previously stated (C10r), therefore shifting the age of significant palaeogeographical changes in the foreland basin. The deformation in the southern front produces the cannibalization in the piggyback basin of 1300 m of sediments spanning c. 3.7 Myr. Average accumulation rates are lower in the Ebro foreland basin than in the piggyback basin and decrease from 35 to 27 cm kyr –1 by the time the San Felices thrust sheet activity decelerates (at c. 28 Myr). Shifts of accumulation rates result from accommodation space changes, which occur locally and are linked to the activity of the San Felices thrust, while the sediment supply occurs at orogenic scale (source of sediments is c. 200 km to the NE). Finally, sequence boundaries previously considered isochronous in the continental record of the Cenozoic Pyrenean basins are revealed to be 1.8–1 Myr older in the piggyback basin than in the Ebro foreland basin.