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Dynamic spectrum access, enabled by cognitive radio technologies, has become a promising approach to improve efficiency in spectrum utilization, and the spectrum auction is one approach in which unlicensed wireless users lease some unused bands from spectrum license holders. However, spectrum auctions are different from traditional auctions studied by economists, because spectrum resources are interference-limited...
In this paper, the gain and noise performances of a DC-6 GHz microwave amplifier using commercial Silicon Germanium Heterostructure Bipolar Transistor (SiGe HBT) are investigated at different bath temperatures. At room temperature, the two-stage amplifier has a gain of 21 dB and a noise figure of 3.7 dB at 2.62 GHz. When cooled to 70 K, it demonstrates 27 dB gain and 1.5 dB noise figure at the same...
An equivalent circuit model of erbium-doped fibre amplifiers (EDFAs), including amplified spontaneous emission (ASE), is proposed. Using the circuit model, static and dynamic characteristics of EDFAs with the help of a SPICE simulator can be analysed conveniently. DC gain, ASE spectrum, frequency response and transient analysis of EDFAs can be simulated. A good agreement is obtained between the result...
In this paper, we present the results of identification and control experiments on NASA's ACES structure at the Marshall Space Flight Center. The models used for controller design were obtained from identification experiments employing the algorithm Q-Markov Cover. The OVC algorithm used for control design produces a controller minimizing the control energy of the closed-loop system, subject to inequality...
A design strategy which integrates model reduction by modal cost analysis and a multi-objective controller design is proposed The necessary modeling and control algorithms are easily programmed in Matlab standard software. Hence, this method is very practical for controller design for large space structures. The design algorithm also presents a solution for the very important problem of "tuning"...
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