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High-voltage direct-current (HVdc) transmission lines have been implemented in many countries, including Australia, Brazil, China, and Sweden, and the safety concerns as the result of the high electromagnetic-radiation underneath the HVdc lines have garnered increased public attentions. Here, we report on the model, design, and testing of field-mill electric field sensors to measure the electric field...
This paper describes a model free method for monitoring and fault diagnosis of the elements in a rotor system for a wind turbine. The diagnosis as well as the monitoring is done without using any model of the wind turbine and the applied controller or a description of the wind profile. The method is based on available standard sensors on wind turbines. The method can be used both on-line as well as...
We consider here the use of hovering unmanned aerial vehicles (UAVs) to test spectrum sensing capabilities of Citizen's Broadband Radio Service (CBRS) systems at 3.5 GHz. Aircraft transmit synthesized LTE or pulsed radar modulation to excite spectrum sensing nodes on the ground. This kind of test could be useful either to validate a system during development or to check a deployed system in the field...
Different type of vibrations are inherent in helicopters which cause discomfort to the crew, structural fatigue and other problems which may lead to accidents. Vertical vibrations are due to the out of track conditions i.e. the blades of the helicopter being out of track. The objective of this research work is to minimize the vertical vibrations by improving the blade tracking using image processing...
A major source of vibration in the helicopter is derived from the main rotor dynamics and imbalance. Excessive vibration can cause premature wear to the aircraft and rotating components. Additionally, vibration causes pilot fatigue that in itself can be a safety issue.
In this paper an unknown input observer is designed to detect three different sensor fault scenarios in a specified bench mark model for fault detection and accommodation of wind turbines. A subset of faults is dealt with, which are faults in the rotor and generator speed sensors as well as a converter sensor fault. The proposed scheme detects the speed sensor faults in question within the specified...
During extensive testing of 35 MVA synchronous generator, some tests in standstill were conducted. For those tests rotor was blocked and different DC currents were driven through excitation and armature winding. In order to ensure all necessary conditions for such tests lots of preparations were made. This paper will thoroughly explain all problems that come out of such request and solutions for them.
This paper presents a new and novel technique for speed control of a brushed DC motor without employing any direct shaft transducer in its feedback mechanism. This method uses the current/voltage variation produced on the motor main input power lines as the brushes move from collector blade to the next. The frequency of variation is proportional to the motor speed and the rotor position can also be...
Blade-tip measurement systems are in development for monitoring and prognosis of rotor health and blade health in turbomachinery. The preliminary development of these systems suffers from lack of experience with failure signatures; technical staff are improvising with a combination of test and inspired guesswork. Perhaps mistakes are being made; it may be that mature systems of the future will use...
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