The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Chang Hyeon Ji - One of the best experts on this subject based on the ideXlab platform.
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Electromagnetic micromirror array with single-crystal silicon mirror plate and aluminum spring
Journal of Lightwave Technology, 2003Co-Authors: Chang Hyeon JiAbstract:We have designed and fabricated an addressable 4 /spl times/ 4 array of micromirrors capable of providing up to 90/spl deg/ of Angular Deflection. Each micromirror comprises a single-crystalline silicon mirror plate supported by aluminum springs, which provides an extremely flat reflective surface and a compliant spring material that enables the integration of the device into a limited area without mitigating its performance (i.e., total Angular Deflection). The device is fabricated using a combination of surface and bulk micromachining processes, such as electroplating, bulk wet etching and XeF/sub 2/ etch processes. Selective actuation is accomplished by the use of an electrostatic clamping force on each mirror plate. A mirror rotation angle of more than 80/spl deg/ can be obtained by applying an external magnetic field, and this angle can be further increased by the use of an electrostatic force. The designed structure can be used in microphotonic applications.
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Electromagnetic micromirror array with single-crystal silicon mirror plate and aluminum spring
Journal of Lightwave Technology, 2003Co-Authors: Chang Hyeon JiAbstract:We have designed and fabricated an addressable 4 × 4 array of micromirrors capable of providing up to 90° of Angular Deflection. Each micromirror comprises a single-crystalline silicon mirror plate supported by aluminum springs, which provides an extremely flat reflective surface and a compliant spring material that enables the integration of the device into a limited area without mitigating its performance (i.e., total Angular Deflection). The device is fabricated using a combination of surface and bulk micromachining processes, such as electroplating, bulk wet etching and XeF2 etch processes. Selective actuation is accomplished by the use of an electrostatic clamping force on each mirror plate. A mirror rotation angle of more than 80° can be obtained by applying an external magnetic field, and this angle can be further increased by the use of an electrostatic force. The designed structure can be used in microphotonic applications.
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Design and fabrication of magnetically driven micromirror with large Angular Deflection
Digest of Papers Microprocesses and Nanotechnology 2000. 2000 International Microprocesses and Nanotechnology Conference (IEEE Cat. No.00EX387), 2000Co-Authors: Chang Hyeon JiAbstract:In this research we have designed and fabricated electromagnetically driven micromirror by combination of surface and bulk micromachining processes. Individual mirror plate and springs occupy relatively small area of 300/spl times/300 /spl mu/m/sup 2/. To obtain flat mirror surface, bulk silicon of thickness ranging from 10 to 20 /spl mu/m is used as a mirror plate. For the mirror plate to have substantial amount of Angular Deflection, aluminum is used as a spring material and crab-leg shaped spring is used.
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Design and fabrication of electromagnetic micromirror with bulk silicon mirror plate and aluminum spring
2000 IEEE LEOS International Conference on Optical MEMS (Cat. No.00EX399), 2000Co-Authors: Chang Hyeon Ji, Bum-kyoo ChoiAbstract:We have designed and fabricated a magnetically actuated micromirror device. The fabricated device can be used in optical switching applications that require large Angular Deflection of the reflected beams. The fabrication process is a combination of surface and bulk micromachining, which can be characterized by the capability to form large flat bulk silicon structure and flexible metal spring. The fabrication process can be utilized in the fabrication of devices which require large flat structure and reduced energy in actuation.
M. E. El-hawary - One of the best experts on this subject based on the ideXlab platform.
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Rotor angle wind turbine energy capture control
2015 IEEE 28th Canadian Conference on Electrical and Computer Engineering (CCECE), 2015Co-Authors: Abdulrazig Alarabi, M. E. El-hawaryAbstract:In wind turbines the power generation (power capture) and output torque depends on wind speed. Due to the rapid variations in wind speed, wind and inflow angle evaluating the output power becomes a challenging problem. Many optimization control techniques seek to extract the output power continuously. This paper focusses on dynamic analysis and control of variable wind turbine's rotor yaw angle and Angular Deflection. Earlier work used wind direction and pitch angle to control the performance of wind turbine. Using rotor yaw and Angular Deflection control of horizontal and vertical axis wind turbines is relatively new. For dynamic analysis, rotor yaw and rotor Angular Deflection, model techniques and experimental setup mechanisms were done in detail. Simulations were carried out in C++ to program an Arduino microcontroller and motor driver. Matlab software was used to interface wind turbine experimental setup, Arduino microcontroller and show the functions and aerodynamic forces. The result shows that the performance of wind turbine with this technique gives better result by increasing the power capture by about 15% more.
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CCECE - Rotor angle wind turbine energy capture control
2015 IEEE 28th Canadian Conference on Electrical and Computer Engineering (CCECE), 2015Co-Authors: Abdulrazig Alarabi, M. E. El-hawaryAbstract:In wind turbines the power generation (power capture) and output torque depends on wind speed. Due to the rapid variations in wind speed, wind and inflow angle evaluating the output power becomes a challenging problem. Many optimization control techniques seek to extract the output power continuously. This paper focusses on dynamic analysis and control of variable wind turbine's rotor yaw angle and Angular Deflection. Earlier work used wind direction and pitch angle to control the performance of wind turbine. Using rotor yaw and Angular Deflection control of horizontal and vertical axis wind turbines is relatively new. For dynamic analysis, rotor yaw and rotor Angular Deflection, model techniques and experimental setup mechanisms were done in detail. Simulations were carried out in C++ to program an Arduino microcontroller and motor driver. Matlab software was used to interface wind turbine experimental setup, Arduino microcontroller and show the functions and aerodynamic forces. The result shows that the performance of wind turbine with this technique gives better result by increasing the power capture by about 15% more.
Abdulrazig Alarabi - One of the best experts on this subject based on the ideXlab platform.
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Rotor angle wind turbine energy capture control
2015 IEEE 28th Canadian Conference on Electrical and Computer Engineering (CCECE), 2015Co-Authors: Abdulrazig Alarabi, M. E. El-hawaryAbstract:In wind turbines the power generation (power capture) and output torque depends on wind speed. Due to the rapid variations in wind speed, wind and inflow angle evaluating the output power becomes a challenging problem. Many optimization control techniques seek to extract the output power continuously. This paper focusses on dynamic analysis and control of variable wind turbine's rotor yaw angle and Angular Deflection. Earlier work used wind direction and pitch angle to control the performance of wind turbine. Using rotor yaw and Angular Deflection control of horizontal and vertical axis wind turbines is relatively new. For dynamic analysis, rotor yaw and rotor Angular Deflection, model techniques and experimental setup mechanisms were done in detail. Simulations were carried out in C++ to program an Arduino microcontroller and motor driver. Matlab software was used to interface wind turbine experimental setup, Arduino microcontroller and show the functions and aerodynamic forces. The result shows that the performance of wind turbine with this technique gives better result by increasing the power capture by about 15% more.
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CCECE - Rotor angle wind turbine energy capture control
2015 IEEE 28th Canadian Conference on Electrical and Computer Engineering (CCECE), 2015Co-Authors: Abdulrazig Alarabi, M. E. El-hawaryAbstract:In wind turbines the power generation (power capture) and output torque depends on wind speed. Due to the rapid variations in wind speed, wind and inflow angle evaluating the output power becomes a challenging problem. Many optimization control techniques seek to extract the output power continuously. This paper focusses on dynamic analysis and control of variable wind turbine's rotor yaw angle and Angular Deflection. Earlier work used wind direction and pitch angle to control the performance of wind turbine. Using rotor yaw and Angular Deflection control of horizontal and vertical axis wind turbines is relatively new. For dynamic analysis, rotor yaw and rotor Angular Deflection, model techniques and experimental setup mechanisms were done in detail. Simulations were carried out in C++ to program an Arduino microcontroller and motor driver. Matlab software was used to interface wind turbine experimental setup, Arduino microcontroller and show the functions and aerodynamic forces. The result shows that the performance of wind turbine with this technique gives better result by increasing the power capture by about 15% more.
T. Hyoguchi - One of the best experts on this subject based on the ideXlab platform.
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ULTRAFAST STRESS PULSE DETECTION BY LASER BEAM Deflection
Journal De Physique Iv, 1994Co-Authors: O. B. Wright, T. HyoguchiAbstract:We describe a direct method for the detection of optically excited ultrashort stress pulses in thin films using a time-resolved pump and probe scheme. Changes in the surface profile are monitored by the Angular Deflection of a probe beam. Application to the detection of interfacial layers is also demonstrated. The time-resolved detection of high frequency phonons excited by picosecond or femtosecond optical pulses can be achieved by a variety of methods. Terahertz optical phonons, for example, have been detected through the electrooptic effect,[ll whereas acoustic phonons up to the 100-GHz range have been detected through the photoelastic effect.[2] Here we describe a n ultrafast method for the detection of stress pulses associated with longitudinal acoustic phonons, which i s based on laser beam Deflection from ultrafast surface vibrations.[3] Such a detection scheme has been widely used by the photoacoustics community in lower frequency photothermal Deflection or photothermal displacement experiments.E4,51 Optical pump pulses of duration 3 ps (FWHM), repetition rate 76 MHz, wavelength A = 630 nm and energy 0.6 n J are used to excite the stress pulses. Light absorbed within the optical absorption depth (-10 nm for the metal samples used here) is converted to heat, and, through the resulting thermal expansion, longitudinal stress pulses in the 100-GHz region are generated. Changes in the surface slope of the opaque films, induced by the stress pulses bouncing back and forth inside the films, are interrogated by measuring the Angular Deflection (68-1 prad) of a probe laser beam derived from the same laser (see Fig. 1). This beam is focused to a 20-pm diam. spot size to partially overlap with the pump spot of similar size. The Angular Deflection is monitored with a dual-element photodiode. The displacement of the surface, typically -0.001 nm, can therefore be measured. By scanning the delay line, time-resolved detection on a picosecond time scale is achieved. This Angular Deflection scheme was previously used to measure the transient thermal expansion of bulk crystalline silicon a t lower frequencies of order 2 GHz, but not for the detection of stress pulses.[61 ( 1 ) Present address: Consiglio Nazionale delle Ricerche (CNR), Istituto di Acustica "O.M. Corbino", Via Cassia 12 16,OO 1 X9 Roma, Italy Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jp4:19947165 JOURNAL DE PHYSIQUE IV
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Ultrafast stress pulse detection by laser beam Deflection
Le Journal de Physique IV, 1994Co-Authors: O. B. Wright, T. HyoguchiAbstract:We describe a direct method for the detection of optically excited ultrashort stress pulses in thin films using a time-resolved pump and probe scheme. Changes in the surface profile are monitored by the Angular Deflection of a probe beam. Application to the detection of interfacial layers is also demonstrated
Seokyon Hwang - One of the best experts on this subject based on the ideXlab platform.
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Framework for Measuring the Resilience of Utility Poles of an Electric Power Distribution Network
International Journal of Disaster Risk Science, 2019Co-Authors: Md. Morshedul Alam, Berna Eren Tokgoz, Seokyon HwangAbstract:The utility poles of an electric power distribution system are frequently damaged by wind-related disasters. This study notes that the wooden poles are particularly vulnerable to such disasters and the failures of the poles can cause a network-level failure leading to short- or long-term power outages. To mitigate the problem, this study proposes a framework for measuring the resilience of the wooden utility poles based on the Angular Deflection of a pole due to the wind force. Given the existing inclination angle of a pole, the Angular Deflection is measured by finite element analysis using ANSYS® Workbench1 to determine the resilience area under various wind speeds. For this, the conditions of load and support for a pole, which are called boundary conditions in ANSYS®, are generated. The proposed framework also includes an approach to cost–benefit analysis that compares different strategies for corrective action. The results of the case study in which the framework was applied show that the proposed framework can be effectively utilized by electric power distribution companies to increase the resilience of their systems.
