Cylindrically periodic dielectric waveguide at submillimeter waves

In the terahertz band, the availability of dielectric materials for fabrication of long waveguides is very limited. The only viable candidate at the current time appears to be fused quartz which unfortunately has a relatively low dielectric constant. This limits the use of standard Brag fibers which rely on higher dielectric constants. To overcome this limitation, we have examined the possibility of using a small number of low dielectric constant layers in a periodic arrangement and enclosing the entire structure with a metalic boundary. This configuration results in a moderate loss waveguide. Future work will include the manufacture and testing of such structures and a study of the bend losses

Physical optics characterization of a THz time domain system: UWB leaky lens antenna vs. Austin switch

In this work we show that a THz time domain system based on photoconductive antennas can be improved by over one order of magnitude by using the Ultra-wideband (UWB) leaky lens antenna. The system has been analyzed by implementing a physical optics method to characterize radiated fields by a silicon lens

Fluctuations in the electron system of a superconductor exposed to a photon flux

We report on fluctuations in the electron system, Cooper pairs and quasiparticles, of a superconducting aluminium film. The superconductor is exposed to pair-breaking photons (1.54 THz), which are coupled through an antenna. The change in the complex conductivity of the superconductor upon a change in the quasiparticle number is read out by a microwave resonator. A large range in radiation power can be chosen by carefully filtering the radiation from a blackbody source. We identify two regimes. At high radiation power, fluctuations in the electron system caused by the random arrival rate of the photons are resolved, giving a straightforward measure of the optical efficiency (48%). At low radiation power fluctuations are dominated by excess quasiparticles, the number of which is measured through their recombination lifetime

UWB leaky lens antenna as an improved performance emitter in a THz time domain system

In this contribution we introduce the use of the UWB leaky lens antenna as an improved photo-conducting emitter for a THz time domain system. The UWB antenna presents nearly constant impedance and directive symmetric patterns over a decade of frequency bandwidth. Currently, we are working towards the fabrication of a demonstrating prototype

Operation and Maintenance in Solar Plants: Eight study cases

The use of solar photovoltaic generation is growing up nowadays. New developments have been achieved lowering the prices of the modules and their installation. Nevertheless, the operation and maintenance of these plants still needs improvements in order to enhance their efficiency and economic balance. This paper presents a detailed analysis of eight photovoltaic (PV) plants revealing improvements on the monitoring system and the maintenance procedures. The common failures in PV plants have been established and their losses have been estimated. A correct diagnostic method using good information and monitoring systems could have reduced the losses

Machine Learning models for the estimation of the production of large utility-scale photovoltaic plants

Photovoltaic (PV) energy development has increased in the last years mainly based on large utility-scale plants. These plants are characterised by a huge number of panels connected to high-power inverters occupying a large land area. An accurate estimation of the power production of the PV plants is needed for failure detection, identifying production deviations, and the integration of the plants into the power grid. Various studies have used Machine Learning estimation techniques developed on very small PV plants. This paper deals with large utility-scale plants and uses all the available information to represent the non-uniform radiation over the whole studied solar field. Variables measured in up to four meteorological stations and distributed across the plant are used. Three PV plants with 1, 2 and 4 meteorological stations have been used to develop Machine Learning models. The hyperparameters were systematically optimised, demonstrating the improvements by comparing with a simple model based on Multiple Linear Regression. The best results were obtained with the Random Forest technique for the three PV plants, providing a RMS error value ranging from 1.9% to 5.4%. The final models were compared with those found in the literature for tiny PV plants showing in general much better performance

MKID development for SuperSpec: an on-chip, mm-wave, filter-bank spectrometer

SuperSpec is an ultra-compact spectrometer-on-a-chip for millimeter and submillimeter wavelength astronomy. Its very small size, wide spectral bandwidth, and highly multiplexed readout will enable construction of powerful multibeam spectrometers for high-redshift observations. The spectrometer consists of a horn-coupled microstrip feedline, a bank of narrow-band superconducting resonator filters that provide spectral selectivity, and Kinetic Inductance Detectors (KIDs) that detect the power admitted by each filter resonator. The design is realized using thin-film lithographic structures on a silicon wafer. The mm-wave microstrip feedline and spectral filters of the first prototype are designed to operate in the band from 195-310 GHz and are fabricated from niobium with at Tc of 9.2K. The KIDs are designed to operate at hundreds of MHz and are fabricated from titanium nitride with a Tc of 2K. Radiation incident on the horn travels along the mm-wave microstrip, passes through the frequency-selective filter, and is finally absorbed by the corresponding KID where it causes a measurable shift in the resonant frequency. In this proceedings, we present the design of the KIDs employed in SuperSpec and the results of initial laboratory testing of a prototype device. We will also briefly describe the ongoing development of a demonstration instrument that will consist of two 500-channel, R=700 spectrometers, one operating in the 1-mm atmospheric window and the other covering the 650 and 850 micron bands.Comment: As submitted, except that "in prep" references have been update

Medical oncology future plan of the Spanish Society of Medical Oncology: challenges and future needs of the Spanish oncologists

Purpose: The SEOM Future Plan is aimed at identifying the main challenges, trends and needs of the medical oncology speciality over the next years, including potential oncologist workforce shortages, and proposing recommendations to overcome them. Methods: The estimations of the required medical oncologists workforce are based on an updated Medical Oncologist Register in Spain, Medical Oncology Departments activity data, dedication times and projected cancer incidence. Challenges, needs and future recommendations were drawn from an opinion survey and an advisory board. Results: A shortage of 211 FTE medical oncologist specialists has been established. To maintain an optimal ratio of 158 new cases/FTE, medical oncology workforce should reach 1881 FTE by 2035. Conclusions: Main recommendations to face the growing demand and complexity of oncology services include a yearly growth of 2.5% of medical oncologist’s workforce until 2035, and development and application of more accurate quality indicators for cancer care and health outcomes measure

Pulsed Photoconductive Connected Slot Array Operating at the Sub-mm Wavelength Band

A novel pulsed photoconductive THz source is presented that is able to radiate mW-level average powers, over a large bandwidth by exploiting both the optical and electrical properties of photoconductive sources and the ultrawideband properties of connected antenna arrays. An optical system composed of a micro-lenses array splits the laser beam into N x N spots that host the active excitation of the antenna arrays. An “ad hoc” network has been adopted to bias the array active spots in order to implement a connected antenna array configuration. The array feeds a silicon lens to increase the directivity of the radiated THz beam. A slot array prototype has been designed, fabricated, and measured. The proposed solutions achieve excellent power radiation levels by making use of an accurate electromagnetic design. This solution can offer enhancements to any active system relying on pulsed photoconductive antennas