Robust model following control of parallel buck converters

A robust model-following (RMF) control technique for average current mode controlled (ACC) parallel buck dc-dc converters, RMFACC, is presented. RMFACC achieves that the loop gain of the voltage loop is little sensitive to the variation of power stage parameters: number of modules, input voltage, load, and component tolerances. The design of the voltage loop is 'decoupled' from the design of the disturbance rejection transfer functions in an important degree, so that the output impedance and audio susceptibility are greatly reduced without the need of high loop gain crossover frequencies. A comparative study between conventional ACC and RMFACC is shown.     

Lagrangian analysis of satellite-derived currents: Application to the North Western Mediterranean coastal dynamics

Optimal interpolation methods for improving the reconstruction of coastal dynamics from along-track satellite altimetry measurements have been recently developed over the North Western Mediterranean Sea. Maps of satellite-derived geostrophic current anomalies are generated using these methods, and added to different mean circulation fields in order to obtained absolute geostrophic currents. The resulting fields are then compared to standard AVISO products, and their accuracies are assessed with Lagrangian diagnostics. The trajectories of virtual particle clusters are simulated with a Lagrangian code either with new current fields or with the AVISO ones. The simulated trajectories are then compared to 16 in situ drifter trajectories to evaluate the performance of the different velocity fields. The comparisons show that the new current fields lead to better results than the AVISO one, especially over the shallow continental shelf of the Gulf of Lion. However, despite the use of innovative strategies, some altimetry limitations still persist in the coastal domain, where small scale processes remain sub-sampled by conventional altimetry coverage but will benefit from technological development in the near future. Some of the limitations of the Lagrangian diagnostics presently used are also analyzed, but dedicated studies will be required for future further investigations.     

General aviation aircraft avionics: integration & system tests

The avionics of current-day aircraft is termed as modular integrated full glass cockpit. Unlike lots of dials and gauges, the pilot will interact with Multi-Function Displays (MYD). This means that the systems are coupled with multi-function displays, communication and navigation radios with control units, multi-mode interactive instruments for control and navigation, recording and fault management systems, airframes and health monitoring diagnostic capabilities. Pilot Vehicle Interface (PVI) is an important measure of good avionics and cockpit layout, which implies the optimization of man-machine interface, enhancement of the economy, and safety of flight operations. This presents the avionics architecture of a 14-seat Light Transport Aircraft (LTA) for general aviation, which has multi-role commuter capabilities. LTA is a twin turbo-prop, multi-role aircraft, with air taxi and commuter services as its primary roles. The avionics is built on the digital communication mode for both command and control with current requirements of TCAS, digital Autopilot, and AMLCD multi-purpose glass displays. The LTA Avionics suite is grouped into six major groups based on functionality: Display System, Communication System, Navigation System, Recording System, Radar System, and Engine instruments and other cockpit displays. This paper also covers details about the extensive tests carried out to prove the avionics design in terms of functionality, inter-operability, interference, and compatibility. Various practical integration and flight-test issues, methodologies, and details of the scenarios is presented herein.     

Planck-LFI 44 GHz back end module

This work describes the principle of operation, assembly and performance of one branch of the 44 GHz back end module (BEM) for the Planck low frequency instrument (LFI). This subsystem constitutes a fully representative branch of the qualification-model version (QM). It includes waveguide to microstrip transition, GaAs pseudomorphic high electron mobility transistor (PHEMT) low noise amplifiers (LNA), bandpass filter, square-law detector and dc amplifier. The fundamentals of the design of the RF part are described and all of the components have been tested individually before integration. Using single tone and wideband noise stimuli, the output voltage has been measured for several input powers, in order to obtain the sensitivity factor of the complete BEM. The effective bandwidth and the equivalent noise temperature have been calculated from the measurements, taking into account the frequency dependence on the noise source and the BEM. Finally, the low frequency output power spectrum has been obtained and a maximum 1/f knee frequency around 200 Hz has been measured with a 3 dB output signal video bandwidth above 50 KHz.