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System Engineers (system + engineer)
Selected AbstractsEffects of intermediate load on damping of synchronous generatorEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2006P. Aree Abstract The transfer-function block-diagram model of a single-machine infinite-bus power system, originally developed by Heffron and Phillips, has been a popular analytical tool amongst power system engineers for explanation and assessment of synchronous generator dynamic behaviors. Since this model simply accounts for the generator field circuit with none of the damper circuits, it may not always give a realistic transient response. Moreover, the model considers only a grid-system load without local and intermediate loads. Hence, effects of these loads together with the damper circuits on electromechanical damping have not yet been completely studied. In this paper, the Heffron-Phillips's model has been advanced to incorporate an intermediate load plus one additional damper circuit in the q -axis. The upgraded model demonstrates a great influence of the intermediate load together with the q -axis damper circuit on the electromechanical damping and the dynamic interaction between the field and damper flux linkages. The study shows the key contributions of load to rise and fall of the damping. It appears that the electromechanical damping can be improved with regard to the unity power-factor load through increasing in the natural damping and decreasing in the automatic voltage regulator (AVR) negative damping torques. Nevertheless, the damping is mostly declined, when the load power factor is poor. Moreover, it is markedly changed in relation to various locations of load. The damping characteristics of synchronous generator are investigated using the eigenvalue and frequency response methods. Copyright © 2006 John Wiley & Sons, Ltd. [source] Computers, systems theory, and the making of a wired hospital: A history of Technicon Medical Information System, 1964,1987JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 6 2010Rachel Plotnick This paper investigates the controversy surrounding the systems approach in medicine, contributing to the body of literature on systems and information technology in civilian contexts. Specifically, the paper follows the design and implementation of a hospital information system at El Camino Hospital in Mountain View, California, in the 1960s and 1970s. The case study suggests that while many considered "people problems" like healthcare too complex for the systems approach, in fact it could have positive results if system engineers could translate social concerns about medicine into business and organizational strategies. This paper identifies the ways systems designers approached an organization characterized by autonomy rather than collaboration, craft rather than science, and charity rather than business, and helped to redefine that organization as one that emphasized rationality, efficiency, and the coexistence of man and machine. [source] Magnetic forces and moving body induced voltages: applications to velocity sensing and DC,AC conversionEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2010J. A. Brandão Faria Abstract This research and tutorial paper illustrates two interlinked phenomena of the greatest importance for power and energy systems engineers, i.e., magnetic forces and moving body induced voltages. A two-solenoid system with driving and sensing parts is analyzed taking into account that a moving ferromagnetic core can freely move along the system axial coordinate. At first-order approximation the frequency of the oscillating core movement is shown to be linearly controllable by the direct-current intensity injected in the driving solenoid. On the other hand the induced voltage on the sensing solenoid is shown to be a sinusoidal voltage with a frequency twice the one of the moving core. Copyright © 2009 John Wiley & Sons, Ltd. [source] Operational performance metrics for mars exploration roversJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 8-9 2007Edward Tunstel The concept of operational performance metrics and associated measurement issues is explored for deployed robotic systems. The focus is on performance of mobility and robotic arm autonomy exercised on the NASA Mars Exploration Rovers surface mission. This planetary rover mission has been underway for nearly 3 years since January 2004 using two rovers performing separate missions. The autonomy functions of surface navigation, short-distance approach to surface science targets, and robotic placement of armmounted instruments on science targets are considered. Operational metrics that measure performance of these functions relative to system requirements are advocated. Specific metrics are defined and computed using telemetry from the rovers' multiyear operations on Mars and applied to rate performance during their respective missions. An existing methodology is applied to compute metrics with respect to required performance and to aggregate multiple metrics into a composite performance score for each rover. The formulation is augmented to accommodate importance weights that add flexibility in use of the metrics by different potential endusers, e.g., sponsors, program managers, systems engineers, and technologists. A brief example illustrates the application and effect of importance weights on overall rover performance scores. © 2007 Wiley Periodicals, Inc. 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