Architectures and Integrated Circuits for Efficient, High-power "Digital'' Transmitters for Millimeter-wave Applications

This thesis presents architectures and integrated circuits for the implementation of energy-efficient, high-power "digital'' transmitters to realize high-speed long-haul links at millimeter-wave frequencies in nano-scale silicon-based processes

Sensorless position control of induction machines using high frequency signal injection

The aim of this research project was to develop a position controlled induction machine vector drive operating without a speed or position sensor but having a dynamic performance comparable to that of a sensored position vector drive. The methodology relies on the detection of a rotor saliency in the machine by persistent high-frequency voltage injection. The rotor position is then estimated from the resulting stator current harmonics that are modulated by the spatial rotor saliency. This can be a built-in rotor saliency (a designed asymmetry) or the natural saliency due to rotor slotting. This project investigates the demodulation of the extracted high-frequency current spectrum and different topologies for the estimation of rotor position. The tracking of rotor position through rotor saliencies helps to overcome the limitations of model-based approaches that are restricted to speeds above 30rpm on a 4-pole machine and are sensitive to parameter mismatches. The project addresses the difficult problem of separating the modulation effects due to the rotor saliency from distorting modulations due to the saturation saliency and inverter effects. In previous research it had been found that the saturation saliency causes a deterioration of the position estimate that can result in a loss of position and eventually causes the drive to fail. The application of filters to remove the interfering saturation harmonics is not possible. In this research a new approach was developed that compensates online for the saturation effect using pre-commissioned information about the machine. This harmonic compensation scheme was utilized for a 30kW, 4-pole induction machine with asymmetric rotor and enabled the operation from zero to full load and from standstill up to about ±150rpm (±5Hz). The steady-state performance and accuracy of the resulting sensorless drive has been found to operate similarly to a sensored drive fitted with a medium resolution encoder of 600ppr. The project involved studies of the inverter switching deadtime and its distorting effect on the position estimation. A second compensation strategy was therefore developed that is better suited if a large interfering modulation due to the inverter deadtime is present in the machine. The new compensation method was implemented for a second 30kW machine that utilizes the rotor slotting saliency. Good tracking results were obtained with a mean error of less than ±0.5° mechanical under steady-state. The derivation of the position signal for higher speeds introduces an additional speed-dependent error of about 4° mechanical at 170rpm. Sensorless position control was realized for operation from zero to full load for the fully fluxed machine. The performance allowed low and zero speed operation including position transients reaching a speed of 50rpm. The high-frequency modulation introduced by the fundamental currents during transient operation was examined and identified as the main factor limiting the dynamics of the sensorless drive. Two rigs were used for the research. The first rig is build around a network of Transputers, the second rig uses state-of-the-art TMS320C40 and TMS320F240 digital signal processors for the control and was designed and constructed as part of the research

Topical Workshop on Electronics for Particle Physics

The purpose of the workshop was to present results and original concepts for electronics research and development relevant to particle physics experiments as well as accelerator and beam instrumentation at future facilities; to review the status of electronics for the LHC experiments; to identify and encourage common efforts for the development of electronics; and to promote information exchange and collaboration in the relevant engineering and physics communities

39th Aerospace Mechanisms Symposium

The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production, and use of aerospace mechanisms. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms. Organized by the Mechanisms Education Association, NASA Marshall Space Flight Center (MSFC) and Lockheed Martin Space Systems Company (LMSSC) share the responsibility for hosting the AMS. Now in its 39th symposium, the AMS continues to be well attended, attracting participants from both the United States and abroad. The 39th AMS was held in Huntsville, Alabama, May 7-9, 2008. During these 3 days, 34 papers were presented. Topics included gimbals and positioning mechanisms, tribology, actuators, deployment mechanisms, release mechanisms, and sensors. Hardware displays during the supplier exhibit gave attendees an opportunity to meet with developers of current and future mechanism components

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion