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

Diagnosis of failures in solar plants based on performance monitoring

Photovoltaic (PV) solar energy has become a reference in electrical generation. The plants currently installed, and those planned have a huge capacity and occupy large areas. The increase in size of the plants presents new challenges in operation and maintenance areas, such as the optimization of the number of sensors installed, large data management and the reduction of the timework in maintenance. The aim of this paper is to show a methodology, to diagnose failures, based on the measured data in the plant. The methodology used is supervised regression machine learning and comparison algorithms. This methodology allows the study of the sensors, the inverters, the joint boxes and the power reduction caused by soiling. The result would allow the detection of around 1-5% of production loss in the plant. The algorithms have been tested with real data of PV plants, and have detected common failures such as production drops in strings and losses due to soiling

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

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

Problem-matched basis functions for microstrip coupled slot antennas based on Transmission Line Green's Functions (TLGF)

Problem matched basis functions are proposed for the method of moments analysis of printed slot coupled microstrips. The appropriate equivalent currents of the integral equation kernel are represented in terms of two sets of entire domain basis functions. These functions synthesize on one hand the resonant behavior of slots, microstrips or dipoles and on the other hand the field in proximity of the feeding source and of the discontinuities. In order to define these basis functions, canonical geometries are identified, whose Green's functions have been found in semi-analytical form. The accuracy and the effectiveness of the method in terms of convergence rate and number of unknowns is demonstrated by comparison with a standard fine meshing full-wave analysis. The method is extremely convenient for large arrays, where the subwavelength details should be treated together with large global dimensions. Since the proposed solution is independent of the dimensions of these details, it provides dramatic reduction of the number of unknowns and improvement of condition number

Progressive loss functions for speech enhancement with deep neural networks

The progressive paradigm is a promising strategy to optimize network performance for speech enhancement purposes. Recent works have shown different strategies to improve the accuracy of speech enhancement solutions based on this mechanism. This paper studies the progressive speech enhancement using convolutional and residual neural network architectures and explores two criteria for loss function optimization: weighted and uniform progressive. This work carries out the evaluation on simulated and real speech samples with reverberation and added noise using REVERB and VoiceHome datasets. Experimental results show a variety of achievements among the loss function optimization criteria and the network architectures. Results show that the progressive design strengthens the model and increases the robustness to distortions due to reverberation and noise

EBG enhanced feeds for the improvement of the aperture efficiency of reflector antennas

We describe the use of electromagnetic bandgap (EBG) super-layers to improve the shape of reflectors illumination function. Following an investigation of the leaky wave pole singularities of the EBG Green's function, the shape of the radiation patterns of small apertures in ground planes are optimized. The maximization of the reflector aperture efficiency can be obtained by properly tuning the super layers geometrical parameters. A prototype of such feed has been designed, manufactured and tested. The results indicate that the inclusion of the EBG, increases the aperture efficiency of the feed+reflector system to values higher than 80%, over a 10% bandwidth. These low profile feeds are compatible with printed circuit board and/or integrated technology

Properties of leaky waves supported by grounded dielectric super-layers and implications on the design of reflector feeds

The design strategy that uses dielectric super-layers with neighboring wave-guides closed in matched loads constitutes a worst case scenario as far as the performance enhancement is concerned and finds applicability in radiometric imaging arrays. On the other side the design strategy that uses dielectric super-layers with neighboring wave-guides closed in properly tuned reactive loads can be seen as best case scenario representative of a multi beam system for a telecommunication satellite with independent channels

Valor de la Resonancia Nuclear Magnética en Ortopedia Oncológica

Presentamos nuestra experiencia preliminar sobre la utilidad diagnóstica de la Resonancia Nuclear Magnética (RM) en la evaluación pre- y postoperatoria de pacientes con tumores musculoesqueléticos. Se han revisado 21 pacientes con tumores caracterizados histológicamente. Del total, 10 casos eran sarcomas de partes blandas, 7 correspondían a tumores óseos y 4 eran metástasis óseas o recidivas locales. Las imágenes se obtuvieron mediante un sistema de RM de campo medio provisto de un imán superconductor operando a 0.5 Teslas. En todos los casos se obtuvieron imágenes T1 y T2, en los planos axial y coronal. Como norma se objetivó un excelente contraste entre la señal de la lesión y la de las estructuras normales adyacentes. Sólo en un caso, un osteosarcoma del extremo proximal del peroné, las imágenes de extensión a partes blandas vecinas resultaron ser negativas en la exploración quirúrgica. El análisis de los cambios de intensidad de la señal no permitieron distinguir la especificidad tisular del tumor, ni diferenciar lesiones benignas y malignas. En nuestra experiencia, la RM nos ha permitido un mejor diagnóstico anatómico de la extensión tumoral, facilitándonos la planificación quirúrgica que requieren las modernas técnicas reconstructivas en ortopedia oncológica.The preliminary experience using Magnetic Resonance imaging for pre- and post-operative assessment of orthopaedic oncologic patients is hereby reported. Twenty-one patients with histologically characterized bone and soft tissue tumors have been reviewed. Seventeen patients had primary musculoskeletal neoplasia: 10 had soft tissue sarcomas and 7 bone tumors. The remained 4 patients consisted of bone metastasis or local racidive. Magnetic resonance images were acquired using a superconductive magnet operating at 0.5 Tesla. T1- and T2-weighted transaxial and coronal images were obtained in all cases. An excellent contrast between the signal of the lesion and the normal adjacent structures was usually obtained. Only in one osteosarcoma of the proximal fibula, an extraosseous extension was presumed but not found during surgical resection. Changes in image intensity did not permit to identify tumor tissue specificity neither distinguish between benign and malignat lesions. In our experience, Magnetic Resonance shows a great advantage in order to determine tumor anatomical extension, providing a useful information for the surgical planning required by current reconstructive techniques in orthopaedic oncology