196,314 research outputs found
Effects of inertia on dynamic performance of wind turbines
No full textThe dynamic performance of wind turbines indicates that the power extracted from the wind is strongly related to the inertia of the system and characteristics of wind speed. In this paper, a simulation model of a wind turbine system has been developed to study the effects of inertia. Three aspects of the dynamic performance of wind turbines are investigated in the paper: the prediction of the trend of the natural time-constant versus power rating for wind turbines, the effects of shaft speed on the actual time constant and the power loss due to inertia under varying wind speed conditions.C. Tang, M. Pathmanathan, W.L. Soong and N. Ertugrulhttp://www.ee.unsw.edu.au/aupec2008
Investigation of phase advance modulation with surface permanent magnet generators
No full textPhase advance modulation of a semi-bridge switchedmode rectifier (SMR) has been shown to produce greater power than conventional SMR modulation, at a lower cost than an inverter. This paper investigates how these power improvements are affected by two generator parameters: stator inductance and resistance. These parameters were investigated by a simplified simulation model, which used the boost converter approximation of a semi-bridge SMR. The ratio of generator stator resistance to reactance was found to have a significant impact on the maximum amount of power which could be obtained by phase advance modulation, and the optimum modulation parameters required.M. Pathmanathan, W.L. Soong and N. Ertugru
Cetuximab associated dermal filler reaction
No full textA 52-year-old male patient with hyaluronic acid-based dermal fillers injected in his cheeks was diagnosed with glossotonsillary malignancy, and managed with concurrent cetuximab (epidermal growth factor receptor inhibitor) and radiation therapy. He developed significant inflammation around the dermal filler sites after first cycle of cetuximab which improved with dissolution of the dermal fillers with hyaluronidase. This suggests that cetuximab can lead to inflammation around the dermal filler sites, which can be treated with dissolution of the filler.No Full Tex
Output power capability of surface PM generators with switched-mode rectifiers
No full textSurface permanent magnet (SPM) machines operate with maximum output power for a given current when the induced voltage and the current are in phase. For an SPM generator this is obtained with a leading power-factor load. The inverter topology can achieve a leading input power-factor but this generally requires rotor position information. A lower-cost approach is to use a switched-mode rectifier (SMR) however with conventional modulation control its unity power factor operation results in a lower output power capability, particularly at low speeds. This paper examines performance of phase advance modulation methods to improve the lowspeed output power capability of SPM generators when operated with a SMR. A simplified phase advance modulation called zero-epsilon is proposed. Analytical and simulation approaches are used to understand the fundamental limitations, and the results are then confirmed experimentally.M. Pathmanathan, W.L. Soong and N. Ertugru
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Comparison of AC/DC converters and the principles of a new control strategy in small-scale wind turbine systems
No full textThis paper provides a detailed comparison of AC/DC converters commonly used in small-scale wind turbine systems. The paper reviews the main AC/DC converter topologies first including rectifier, switch-mode rectifier and inverter, and provides their operational features and characteristics. Then based on the previous analytical and comparison studies, it describes a novel multi-mode control strategy, which aims to improve the performance of small-scale wind turbines over a wide operating speed range while considering trade-off between performance and control complexity in such converters.Lujie Chen, Wen. L. Soong, Mehanathan Pathmanathan and Nesimi Ertugrulhttp://aupec2012.org
Maximum-torque-per-ampere control of phase advance modulation of an SPM wind generator
No full textSurface permanent-magnet (SPM) machines are normally operated by controlling the d- and q-axis currents. This paper examines the control of SPM generators based on controlling the terminal voltage magnitude V and power-factor angle 8. This is well suited for generator operation when using a switched-mode rectifier and avoids the need for a rotor position sensor. The parameters required for generating a given value of torque with minimum phase current in order to minimize copper losses are derived in this paper. This will be achieved by controlling V and 8 to keep the d-axis current equal to zero at low speed, before switching to field-weakening control at higher speeds. Simulated and experimental results will be used to verify the control strategy and the efficiency achieved.Mehanathan Pathmanathan, Wen L. Soong and Nesimi Ertugru
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Maximum torque per ampere control of phase advance modulation of a SPM wind generator
No full textSurface permanent magnet (PM) machines are normally operated by controlling the d-axis and q-axis currents. This paper examines the control of surface PM generators based on controlling the terminal voltage magnitude V and power-factor angle θ. This is well-suited for generator operation when using a switched-mode rectifier and avoids the need for a rotor position sensor. The parameters required for generating a given value of torque with minimum phase current in order to minimize copper losses are derived in this paper. This will be achieved by controlling V and θ to keep the d-axis current equal to zero at low speed, before switching to field-weakening control at higher speeds. Simulated and experimental results will be used to verify the control strategy, and the efficiency achieved.Mehanathan Pathmanathan, Wen Soong and Nesimi Ertugru
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