How to automate a kinematic mount using a 3D printed Arduino-based system

We demonstrate a simple, flexible and cost-effective system to automatize most of the kinematic mounts available nowadays on the market. It combines 3D printed components, an Arduino board, stepper motors, and simple electronics. The system developed can control independently and simultaneously up to ten stepper motors using commands sent through the serial port, and it is suitable for applications where optical realignment using flat mirrors is required on a periodic basis.Comment: 9 pages, 8 figure

Thermal-hydraulic and optical modeling of solar Direct Steam Generation systems based on Parabolic-Trough Collectors

Not only the round absorber tube has been studied, but as a matter of example, the potential of the IMCRT method has also been applied to flat absorbers. A thermal model of a linear receiver has also been performed to describe the heat transfer mechanisms between all the elements on it. Heat diffusion in the absorber tube wall as well as the glass cover has been modeled in 3D, whereas the fluid domain (superheated steam) has been simplified according to a 1D approach. Results have been validated with experimental data from the DISS facility located at Plataforma Solar de Almería. Besides, a detailed thermal-hydraulic study has also been carried out by means of the commercial code RELAP5. This code is based on a transient two-fluid model where both, single-phase and two-phase flow regions can be simulated. Thermal behavior of the absorber tube can also be approximated by means of the standard capabilities of RELAP5. A full and detailed model of the DISS facility has been performed where the connection pipes between adjacent collectors have been included. This model has been validated with experimental data obtained from full day tests getting a good agreement. According to the results, the 1D approach followed by RELAP5 is able to reproduce transient phenomena which usually take place in common operation conditions. In addition, heat losses have been experimentally characterized in the same facility. A new correlation, which takes into account heat losses of receivers after two years and a half of operation, is proposed and included in the model. Thermal-hydraulic codes also make it possible to study severe slugging in connection pipes. For that purpose, a particular connection pipe alongside their two adjacent collectors have been simulated to figure out in which range of operation conditions severe slugging occurs at a pressure of 0.5 MPa.CSP systems based on Parabolic-Trough Collectors (PTCs) account for a representative share of the global solar thermal capacity installed. Most of the existing PTC power plants use synthetic oil as heat transfer fluid. However, water can be alternatively used, where both single and two-phase flow occur. This technology is called Direct Steam Generation (DSG) and it presents some advantages in terms of system overall efficiency and plant cost reduction. Nevertheless, some complexities inherent to two-phase flow have to be addressed to succeed in the commercial deployment of DSG. The development of numerical codes to model such systems is of key importance to put new insights into them. Both, the thermal-hydraulic and optical modeling are of relevance. Conventional parabolic-trough reflectors concentrate solar radiation on absorber tubes following a characteristic pattern with a non-homogeneous distribution in the angular direction. It means that the bottom half of the absorber tube receives much more flux than the upper half. Under specific two-phase flow patterns (e.g. stratified flow) the refrigeration of the absorber tube is not homogeneous and thermal bending may take place. This problem can also be reported in single-phase flow conditions (e.g. superheated steam), where a significant thermal gradient at the cross-sectional plane of the absorber tube can be critical. A new technique called Inverse Monte Carlo Ray Tracing (IMCRT) method is proposed in this thesis. It aims to design new reflector geometries so that a more homogeneous distribution of concentrated solar radiation on the absorber tube can be accomplished. In line with this, new reflector geometries have been proposed with the same aperture width as the LS-3 design for the same absorber design, where quasi-constant flux distribution is achieved within a specific angular range

Optical sectioning in induced coherence tomography with frequency-entangled photons

We demonstrate a different scheme to perform optical sectioning of a sample based on the concept of induced coherence [Zou et al., Phys. Rev. Lett. 67, 318 (1991)]. This can be viewed as a different type of optical coherence tomography scheme where the varying reflectivity of the sample along the direction of propagation of an optical beam translates into changes of the degree of first-order coherence between two beams. As a practical advantage the scheme allows probing the sample with one wavelength and measuring photons with another wavelength. In a bio-imaging scenario, this would result in a deeper penetration into the sample because of probing with longer wavelengths, while still using the optimum wavelength for detection. The scheme proposed here could achieve submicron axial resolution by making use of nonlinear parametric sources with broad spectral bandwidth emission.Comment: Published version. 11 pages, 9 figure

Tunable beam displacer

We report the implementation of a tunable beam displacer, composed of a polarizing beam splitter (PBS) and two mirrors, that divides an initially polarized beam into two parallel beams whose separation can be continuously tuned. The two output beams are linearly polarized with either vertical or horizontal polarization and no optical path difference is introduced between them. The wavelength dependence of the device as well as the maximum separation between the beams achievable is limited mainly by the PBS characteristics.Comment: 3 pages, 2 figure

The Sustainable Management of Metals: An Analysis of Global Research

The objective of this study was to analyze research trends in the field of sustainable management of metals on a global level between 1993 and 2017. To do so, a bibliometric analysis was carried out on a total of 6967 articles. The results revealed the growing interest in this research field, particularly over the last five year-period during which 63% of all articles were published. The three journals in which most articles had been published were the Journal of Cleaner Production, ACS Sustainable Chemistry and Engineering, and Chemsuschem. The countries that published the most articles were China, the United States, India, Germany, and the United Kingdom. A sizeable network of collaboration has been established between countries for the joint publication of studies. The main lines of research have been focused on metal decontamination in water and soil, waste management oriented towards reuse and recycling, and the innovation of processes for cleaner and more efficient production. The results revealed the need for comprehensive studies that integrate different disciplines within the same analytical framework, and to promote research that contributes to the different dimensions of sustainability (environmental, economic, and social)

Un nuevo bronce hallado en La Alcudia

Presentación del bronce de la centuriación de Ilici

Modelling and Terrestrial Laser Scanning Methodology (2009–2018) on Debris Cones in Temperate High Mountains

Producción CientíficaDebris cones are a very common landform in temperate high mountains. They are the most representative examples of the periglacial and nival processes. This work studies the dynamic behavior of two debris cones (Cone A and Cone B) in the Picos de Europa, in the north of the Iberian Peninsula. Their evolution was measured uninterruptedly throughout each August for 10 years (2009–2018) using the Terrestrial Laser Scanning (TLS) technique. The observations and calculations of the two debris cones were treated independently, but both showed the same behavior. Therefore, if these results are extrapolated to other debris cones in similar environments (temperate high mountain), they should show behavior similar to that of the two debris cones analyzed. Material falls onto the cones from the walls, and transfer of sediments follows linear trajectories according to the maximum slope. In order to understand the linear evolution of the two debris cones, profiles were created along the maximum slope lines of the Digital Elevation Model (DEM) of 2009, and these profile lines were extrapolated to the remaining years of measurement. In order to determine volumetric surface behavior in the DEMs, each year for the period 2009–2018 was compared. In addition, the statistical predictive value for position (Z) in year 2018 was calculated for the same planimetric position (X,Y) throughout the profiles of maximum slopes. To do so, the real field data from 2009–2017 were interpolated and used to form a sample of curves. These curves are interpreted as the realization of a functional random variable that can be predicted using statistical techniques. The predictive curve obtained was compared with the 2018 field data. The results of both coordinates (Z), the real field data, and the statistical data are coherent within the margin of error of the data collection.Fondo Europeo de Desarrollo Regional - Agencia Estatal de Investigación (grant TIN2016-76843-C4-2-R)Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (grant CGL2015-68144-R

Surface movement and cascade processes on debris cones in temperate high mountain (Picos de Europa, northern Spain)

Producción CientíficaDebris talus is a very common landform in the temperate high mountain, so much so that it is the most representative of the periglacial and nival processes. This work studies debris cones in the Picos de Europa, an Atlantic mountain range in the north of the Iberian Peninsula. A detailed geomorphological map was prepared, fieldwork was carried out on the debris cone surface, the ground and air thermal regime was analyzed, and a five-year Terrestrial Laser Scan survey carried out. Annual volume changes on the surface of the debris cones were detected and related to active processes and sediment transfer. Two different behaviors were observed in each cone. Cone A is linear, with equilibrium between accumulation and sediment transfer, while Cone B is concave-convex denoting accumulation processes in the upper part deriving from the greater frequency of snow avalanches. Changes in morphology surpass 50 cm/year with most of the activity taking place in the highest and lowest areas. The presence and action of the ice on the debris slope are moderate or non-existent and freeze-thaw processes are only active on the walls at over 2000 m a.s.l. The main processes on debris cones are debris flow and creep related to snowcover, but sediment transfer on the slopes involves high intensity-low frequency (debris flow, avalanches) and high frequency-low intensity processes (creep, shift, solifluction and wasting).Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project CGL2015-68144-R)Junta de Extremadura - Fondo Europeo de Desarrollo Regional (project GR10071