Renal Rehabilitation: A Perspective From Human Body Movement

The prevalence and incidence of advanced chronic kidney disease has grown progressively in most countries of the world. Hemodialysis is the most common treatment that replaces the renal function, and although it allows to replace the function of the kidney, the patients who undergo it can present numerous alterations that lead to a loss of functional physical capacity and a decrease in the quality of life related to health. It is unknown to what extent low physical activity, uremia and anemia determine the decrease in functional capacity of these patients. The functional tests most frequently used in the published literature are characterized by their ease of application and their low cost, since they do not require large measuring instruments to quantify basic qualities in subjects with impaired or dysfunction of the renal system from the aerobic capacity, muscle performance and flexibility as axes within the kinetic wellbeing which is committed in the stay of the renal hemodialysis units

Editorial

La Revista Ingeniería Investigación y Desarrollo (I2+D) de la Uptc, durante los últimos 10 años, se ha dedicado a la difusión de artículos científicos en las diferentes áreas de la ingeniería. Gracias a los enormes esfuerzos de parte de sus editores, I2+D ha logrado ser reconocida y categorizada por el Departamento Administrativo de Ciencia, Tecnología e Innovación de Colombia (COLCIENCIAS). De esta manera, la revista ha venido consolidándose como un excelente medio para compartirimportantes resultados de investigación, tanto para autores nacionales como internacionales. Siendo para mí, un verdadero honor, haber sido invitado a redactar esta Editorial. Por lo tanto, quisiera a través de este escrito, dar un especial reconocimiento al Ingeniero Oscar Iván Higuera, por el arduo trabajo realizado como actual Jefe Editorial de la revista; sin olvidar, por supuesto, a su predecesor el Ingeniero Oscar Oswaldo Rodríguez. Además, es para mí importante, agradecer el apoyo incondicional de su Asistente Editorial Olga Lucía Chaparro, y de María Lorena Alarcón, diseñadora gráfica de la revista. No puedo olvidar, por otra parte, reconocer el inmenso apoyo otorgado al presente número de nuestra revista, por parte del equipo de revisores, los cuales podemos consultar en la página legal de esta publicación. De manera muy sincera, reciban los más grandes agradecimientos. ....

Amplificador de potencia Doherty de 25 W, 70% de eficiencia y back off de salida de 6 dB para aplicaciones a 2,4 GHz, con control de VGS, PEAK

This paper shows the design and simulation results of a hybrid Doherty power amplifier. The amplifier has been designed at 2,4 GHz, obtaining power-added efficiency above 70 % for 6 dB output power back-off, together with a small signal gain of 17 dB. Design and analysis equations are presented considering class AB bias conditions for the main amplifier and class C for the peak one in back-off larger than 6 dB, and FET device assumption. An additional control on the bias point of the peak device has been carried out, in order to increase the gain on the Doherty region and ease the design of the peak branch. A Cree’s GaN-HEMT CGH40010F device has been used with a nonlinear model guarantied up to 6 GHz and with an expected output power of 10 W. The obtained output power is higher than 25-W. The simulation has been carried out using Agilent ADS CAD tools. The present design could present the state of the art in terms of continuous-wave (CW) characterization.Este artículo muestra el diseño y los resultados de simulación de un amplificador de potencia Doherty sobre tecnología híbrida. El amplificador fue diseñado a 2,4 GHz, obteniendo una eficiencia de potencia aditiva arriba del 70 % a 6-dB debajo de saturación, junto con una ganancia a pequeña señal de 17 dB. Las ecuaciones de análisis y diseño son presentadas considerando polarización clase AB para el amplificador principal y clase C para el amplificador auxiliar a 6-dB debajo de saturación, y dispositivos FET. Un control adicional sobre el punto de polarización del dispositivo auxiliar se ha llevado a cabo, para incrementar la ganancia en la región Doherty y facilitar el diseño de la rama auxiliar. Un dispositivo GaN-HEMT CGH40010 de Cree ha sido usado con un modelo no-lineal garantizado hasta 6-GHz y con una potencia de salida esperada de 10-W. La potencia de salida obtenida es mayor a 25-W. La simulación ha sido llevada a cabo usando Agilent ADS. El presente diseño representaría el estado del arte en términos de caracterización de onda continua (OC)

Design of a 87% fractional bandwidth Doherty Power Amplifier supported by a simplified bandwidth estimation method

This paper presents a novel technique for the design of broadband Doherty power amplifiers (DPAs), supported by a simplified approach for the initial bandwidth estimation that requires linear simulations only. The equivalent impedance of the Doherty inverter is determined by the value of the output capacitance of the power device, and the Doherty combiner is designed following this initial choice and using a microstrip network. A GaN-based single-input DPA designed adopting this method exhibits, on a state-of-the-art bandwidth of 87% (1.5-3.8 GHz), a measured output power of around 20 W with 6 dB back-off efficiency between 33% and 55%, with a gain higher than 10 dB. System-level measurements prove the linearizability of the designed Doherty amplifier when a modulated signal is applied

Amplificador de Potencia Doherty de 25 W, 70% de Eficiencia y Back Off de Salida de 6 dB para Aplicaciones a 2,4 GHz, con Control de VGS, PEAK

This paper shows the design and simulation results of a hybrid Doherty power amplifier. The amplifier has been designed at 2,4 GHz, obtaining power-added efficiency above 70 % for 6 dB output power back-off, together with a small signal gain of 17 dB. Design and analysis equations are presented considering class AB bias conditions for the main amplifier and class C for the peak one in back-off larger than 6 dB, and FET device assumption. An additional control on the bias point of the peak device has been carried out, in order to increase the gain on the Doherty region and ease the design of the peak branch. A Cree’s GaN-HEMT CGH40010F device has been used with a nonlinear model guarantied up to 6 GHz and with an expected output power of 10 W. The obtained output power is higher than 25-W. The simulation has been carried out using Agilent ADS CAD tools. The present design could present the state of the art in terms of continuous-wave (CW) characterizationEste artículo muestra el diseño y los resultados de simulación de un amplificador de potencia Doherty sobre tecnología híbrida. El amplificador fue diseñado a 2,4 GHz, obteniendo una eficiencia de potencia aditiva arriba del 70 % a 6-dB debajo de saturación, junto con una ganancia a pequeña señal de 17 dB. Las ecuaciones de análisis y diseño son presentadas considerando polarización clase AB para el amplificador principal y clase C para el amplificador auxiliar a 6-dB debajo de saturación, y dispositivos FET. Un control adicional sobre el punto de polarización del dispositivo auxiliar se ha llevado a cabo, para incrementar la ganancia en la región Doherty y facilitar el diseño de la rama auxiliar. Un dispositivo GaN-HEMT CGH40010 de Cree ha sido usado con un modelo no-lineal garantizado hasta 6-GHz y con una potencia de salida esperada de 10-W. La potencia de salida obtenida es mayor a 25-W. La simulación ha sido llevada a cabo usando Agilent ADS. El presente diseño representaría el estado del arte en términos de caracterización de onda continua (OC)

A 4W Doherty power amplifier in GaN MMIC technology for 15GHz applications

This letter presents an integrated Doherty power amplifier (PA) in 0.25- μm GaN on SiC process. Designed for 15-GHz point-to-point radios, the PA exhibits an output power of 36 ± 0.5 dBm between 13.7 and 15.3 GHz, while at 14.6 GHz, it shows a 6-dB output back-off efficiency higher than 28%. Modulated signal measurements applying digital predistortion demonstrate the compatibility of the amplifier with point-to-point radio requirements. To the best of our knowledge, this PA has the highest back-off efficiency for the 15-GHz band, and is the first GaN Doherty in the Ku-band

Wireless energy transfer between anisotropic metamaterials shells

The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated.This work was supported by the Spanish Ministry of Economy and Competitiveness under Grants TEC 2010-19751 and Consolider CSD2008-00066. The authors acknowledge Daniel Torrent for useful discussions.Diaz Rubio, A.; Carbonell Olivares, J.; Sánchez-Dehesa Moreno-Cid, J. (2014). Wireless energy transfer between anisotropic metamaterials shells. Annals of Physics. 345:55-62. doi:10.1016/j.aop.2014.03.005S556234

3-3.6 GHz Wideband GaN Doherty power amplifier exploiting output compensation stages

We discuss the design, realization and experimental characterization of a GaN-based hybrid Doherty power amplifier for wideband operation in the 3-3.6 GHz frequency range. The design adopts a novel, simple approach based on wideband compensator networks. Second-harmonic tuning is exploited for the main amplifier at the upper limit of the frequency band, thus improving gain equalization over the amplifier bandwidth. The realized amplifier is based on a packaged GaN HEMT, and shows, at 6 dB of output power back-off, a drain efficiency higher than 38% in the 3-3.6 GHz band, gain around 10 dB, and maximum power between 43dBm and 44 dBm, with saturated efficiency between 55% and 66 %. With respect to the state of the art, we obtain, at a higher frequency, a wideband amplifier with similar performances in terms of bandwidth, output power, and efficiency, through a simpler approach. Moreover, the measured constant maximum output power of 20W suggests that the power utilization factor of the 10 W (Class A) GaN HEMT is excellent over the amplifier ban