Lower solar chromosphere-corona transition region. II - Wave pressure effects for a specific form of the heating function

1990 ◽  
Vol 73 ◽  
pp. 489 ◽  
Author(s):  
D. Tod Woods ◽  
Thomas E. Holzer ◽  
Keith B. MacGregor
Keyword(s):  
Transition Region ◽  
Specific Form ◽  
Pressure Effects ◽  
Solar Chromosphere ◽  
Wave Pressure ◽  
Region Ii

scholarly journals Improvement of Small Wind Turbine Control in the Transition Region

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 244
Author(s):  
Mario L. Ruz ◽  
Juan Garrido ◽  
Sergio Fragoso ◽  
Francisco Vazquez
Keyword(s):  
Wind Turbine ◽  
Transition Region ◽  
Control Strategies ◽  
Gain Scheduling ◽  
Wind Turbine Control ◽  
Wind Energy Conversion Systems ◽  
Power Regulation ◽  
Energy Conversion Systems ◽  
Transient Loads ◽  
Region Ii

Wind energy conversion systems are very challenging from the control system viewpoint. The control difficulties are even more challenging when wind turbines are able to operate at variable speed and variable pitch. The contribution of this work is focused on designing a combined controller that significantly alleviates the wind transient loads in the power tracking and power regulation modes as well as in the transition zone. In a previous work, the authors studied the applicability of different multivariable decoupling methodologies. The methodologies were tested in simulation and verified experimentally in a lab-scale wind turbine. It was demonstrated that multivariable control strategies achieve a good closed-loop response within the transition region, where the interaction level is greater. Nevertheless, although such controllers showed an acceptable performance in the power tracking (region II) and power regulation (region IV) zones, appreciable improvement was possible. To this end, the new proposed methodology employs a multivariable gain-scheduling controller with a static decoupling network for the transition region and monovariable controllers for the power tracking and power regulation regions. To make the transition between regions smoother, a gain scheduling block is incorporated into the multivariable controller. The proposed controller is experimentally compared with a standard switched controller in the lab-scale wind turbine. The experiments carried out suggest that the combination of the proposed multivariable strategy for the transition region to mitigate wind transient loads combined with two monovariable controllers, one dedicated to region II and other to region IV, provide better results than traditional switched control strategies.

scholarly journals Experiment to Determine the Temperature Structure in the Solar Chromosphere and Corona

1972 ◽  
Vol 14 ◽  
pp. 668-669
Author(s):  
C. R. Negus
Keyword(s):  
Transition Region ◽  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Research Unit ◽  
Emission Lines ◽  
Solar Chromosphere ◽  
Temperature Structure ◽  
Ultraviolet Emission ◽  
Ionization Temperature ◽  
Intensity Ratios

An experiment is in course of preparation at the Astrophysics Research Unit at Culham for flight on a Sun-pointing rocket. It is designed to determine the ionization temperature and electron density as a function of height in the temperature range of about 8 × 104 K to 3 × 106 K by measuring limb to disk intensity ratios of extreme ultraviolet emission lines in the 170 to 850 Å region. The work is an extension of current experiments in which normal-incidence spectrographs are used to determine the structure lower in the chromosphere-corona transition region.

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