Boost-based MPPT Converter Topology Trade-off for Space Applications

High power and high voltage – 100V – power buses are often required not only in the frame of the telecommunication spacecrafts, but also for those scientific and interplanetary mission cases where a high user power load demand is driving the design of the power subsystem. On many cases, the use of Maximum Power Point Tracking (MPPT) is essential for an optimum power subsystem sizing

Boost-based MPPT for the MTM PCDU of the Bepicolombo mission

BepiColombo is an ESA mission to Mercury to be launched in 2013. A better knowledge of the origin and evolution of the planet, of its structure and vestigial atmosphere, of its magnetosphere, and of the origin of its magnetic field are the main objectives for the program. The journey to Mercury will last for approximately 6 years, and will be based on the gravity of the Earth, Venus and Mercury, and on the use of Solar Electric Propulsion. For the last, the use of the MPPT concept is essential for the mission. A mission power demand of up to 14kW is foreseen in the cruise phase for the Mercury Transfer Module (MTM) PCDU, being the power subsystem based on a 100V bus. Under this scenario, the use of a classical step-down regulator for the implementation of the MPPT power cell would require to keep the worst case minimum solar array voltage over the bus for any mission operating condition. Then, the maximum solar array voltage would become as high as to overpass the insulating capability of the isolation layer between the solar array cells and the substrate, under the high temperature environment experienced by the spacecraft near Mercury. As a result, the development of a step-up MPPT Array Power Regulator (APR) becomes a critical issue for the mission feasibility. Moreover, due to the hard environment that the solar array will be exposed to, the segregation of the solar array power is a very desirable feature. Furthermore, apart from the two classical operating modes of the APR – conductance or MPPT, depending on the spacecraft user loads demand and the available solar array power – the APR will have to operate in S3R mode for solar array voltages over the bus, with a fully autonomous transition between the three operating modes. This paper covers all the aspects related with the design of the APR MPPT concept and its implementation: APR power cell topology, control scheme, control strategy, protections. The implications on the design of the MTM PCDU MEA will be also addressed. Finally, they will be presented the results of the test carried out over an 1/10 scaled-down engineering model of the BepiColombo PCU - including 3 APRs - in front of the real operating conditions foreseen for the MTM PCDU, including all the relevant issues related to the behaviour of the Electric Propulsion load like beam-out events and load transients

On-demand spectrum and space defragmentation in an elastic SDM/FDM/TDM network with mixed multi- and single-core fiber links

We show on-demand multi-wavelength spectrum and space defragmentation in an SDM and elastic network with four programmable nodes and two multi-core fiber links. The combined approach is shown to reduce blocking and hardware requirements in small nodes

On-Demand Spectrum and Space Defragmentation in an Elastic SDM/FDM/TDM Network with Mixed Multi- and Single-core Fiber Links

We show on-demand multi-wavelength spectrum and space defragmentation in an SDM and elastic network with four programmable nodes and two multi-core fiber links. The combined approach is shown to reduce blocking and hardware requirements in small nodes. © 2013 OSA

100-GHz grid-aligned multi-channel polarization insensitive black-box wavelength converter

A new scheme for a flexible modulation and bit rate independent, polarization-insensitive optical wavelength converter (WC) based on four-wave mixing (FWM) in a highly nonlinear fiber (HNLF) is demonstrated and characterized for different modulation formats and data rates. Its robustness is demonstrated in a data transmission experiment in which the WC is incorporated at the mid-point of a transmission line based on installed fiber. In addition, an optical feedback system designed to prevent slow polarization drift of the pumps and consequently to ensure the long-term stability of the system is implemented and characterized. The WC is tested with the feedback system in place enabling turn-key operation

Correlación clínico-citohistológica de los quistes congénitos cervicales

Objective: To determine the effectiveness of clinical and cytological diagnosis in congenital cysts located in head and neck. Method: We were carried out a retrospective study of patients with clinical, cytological or histological diagnosis of thyroglossal, branchial and dermoid cyst, assisted in the University Hospital Arnaldo Milián Castro", during five years. It was calculated the sensibility, specificity and security of the clinical diagnosis and the Fine Needle Aspiration Biopsy for each cyst. Result: The security of the clinical diagnosis it was respectively of 94,1%, 92,2% and 98% for the thyroglossal, branchial and dermoid cysts. We find bigger tendency to the clinical error in branchial cysts, where the most frequent confusions are presented with inflammatory linfoadenopathy. The security of the Fine Needle Aspiration Biopsy was of 96,1% and 94,1% for the thyroglossal and branchial cysts respectively. Conclusions: Clinical diagnosis is not enough in occasions, for what is necessary to appeal to means complementary diagnoses, as the Fine Needle Aspiration Biopsy; however this test is not 100% sure.Objetivo: Determinar la efectividad de los diagnósticos clínico y citológico en los quistes congénitos cervicofaciales. Método: Se realizó un estudio retrospectivo de los pacientes con diagnóstico clínico, citológico y/o histológico de quiste tirogloso, branquial y dermoide, atendidos en el Hospital Universitario «Arnaldo Milián Castro», durante cinco años. Se calculó la sensibilidad, especificidad y seguridad del diagnóstico clínico y la biopsia por aspiración con aguja fina (FNAC) para cada quiste. Resultado: La seguridad del diagnóstico clínico fue de 94,1%, 92,2% y 98% para los quistes tirogloso branquial y dermoide respectivamente. Encontramos mayor tendencia al error clínico en los quistes branquiales, donde las confusiones más frecuentes se presentan con linfoadenopatías inflamatorias. La seguridad de la biopsia por aspiración con aguja fina fue de 96,1% y 94,1% para los quistes tirogloso y branquial respectivamente. Conclusiones: El diagnóstico clínico no es suficiente en ocasiones, por lo que es preciso recurrir a medios diagnósticos complementarios, como la biopsia por aspiración con aguja fina; sin embargo esta prueba no es 100% segura