scholarly journals Extending the Observable Zenith Angle of FAST Using an Offset Feed

2001 ◽  
Vol 182 ◽  
pp. 255-259
Author(s):  
Li Guoding ◽  
R. Nan ◽  
B. Peng
Keyword(s):  
Real Time ◽  
Active Control ◽  
Radio Telescope ◽  
Zenith Angle ◽  
Spherical Reflector ◽  
Paraboloid Of Revolution ◽  
Reflecting Surface

AbstractThe five hundred meter aperture spherical radio telescope is will use an active spherical reflector. When the zenith scan angle is changed, the illuminated part of the reflecting surface is made to fit a paraboloid of revolution in real time by active control. The maximum zenith scan angle | ψmax | of FAST is 30° under conditions of the geometry selected in order that the feed does not illuminate the ground. The result of this paper shows that the maximum zenith scan angle | ψmax | can be extended to 69° by offsetting the feed.

Active control of the scattered radiation with a reflecting surface

2019 ◽  
Vol 67 (3) ◽  
pp. 190-196
Author(s):  
Ning Han
Keyword(s):  
Control System ◽  
Active Control ◽  
Scattered Radiation ◽  
Sound Pressure ◽  
Sound Field ◽  
Control Area ◽  
Mirror Image ◽  
Three Dimension ◽  
Control Effect ◽  
Reflecting Surface

Based on a prediction method of the scattered sound pressure, an active control system was proposed in previous work for the three-dimension scattered radiation, where all the relevant simulations and experiments were implemented in three-dimensional free sound field. However, for practical applications, such as the anti-eavesdropping system or the stealth system for submarines, the sound field conditions are usually complex, and the most common case is the one with reflecting surface. It is questionable whether the previous control system is still effective in non-free sound field, or what improvements should be operated to ensure the control effect. In this article, based on the mirror image principle, two methods of calculating the control source strengths are proposed for the scattered radiation control, and numerical simulations with one-channel and multi-channel system are implemented to detect the corresponding control effect. It is seen that the local active control for the scattered radiation is still effective, and the reduction of the sound pressure level as well as the control area is extended with the increasement of the error sensors and control sources.

Real-time Closed-loop Active Surface Technology of a Large Radio Telescope

2022 ◽  
Vol 134 (1031) ◽  
pp. 015003
Author(s):  
Yong Zhang ◽  
Guoping Li ◽  
Guohua Zhou ◽  
Qishuai Lu ◽  
Heng Zuo ◽  
...  
Keyword(s):  
Real Time ◽  
Radio Telescope ◽  
Closed Loop ◽  
Preliminary Test ◽  
Active Surface ◽  
Angle Measurement ◽  
Quality Data ◽  
Surface Accuracy ◽  
Surface System ◽  
Reflector Surface

Abstract The surface accuracy of a large radio telescope’s primary reflector is easily affected by gravity and temperature change during observations. An active surface system is crucial to ensure the regular operation and high-quality data output of the radio telescope. We propose a real-time closed-loop active surface system including two components. The first component, a new type of photoelectric edge sensor, detects the angle change of the adjacent panels. The second component, the displacement actuator, adjusts the panels’ position and posture to compensate for the angle changes. So, over the entire observation, the closed-loop surface control system with these two components could actively maintain the primary reflector’s accuracy in real time. Using this approach, we constructed an experimental active surface system for the Xinjiang Qitai 110 m Radio Telescope (QTT) to test the maintenance of the surface accuracy. The angle measurement accuracy is better than 0.″2, and the positioning accuracy of the displacement actuator could achieve ±15 μm over the whole 50 mm stroke. The preliminary test results show that the accuracy requirements of the QTT’s primary reflector surface can be met using the active surface system we propose.

A Spherical-Reflector Radio Telescope

1966 ◽  
pp. 97-101
Author(s):  
Yu. L. Kokurin ◽  
R. L. Sorochenko
Keyword(s):  
Radio Telescope ◽  
Spherical Reflector

Real-Time Tuning of Delayed Resonator-Based Absorbers for Spectral and Spatial Variations

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Ryan Jenkins ◽  
Nejat Olgac
Keyword(s):  
Real Time ◽  
Active Control ◽  
Design Guidelines ◽  
Spatial Variations ◽  
Time Varying ◽  
Vibration Absorption ◽  
Spatial Tuning ◽  
System Components ◽  
Hybrid Concept ◽  
Time Variations

This paper offers two interlinked contributions in the field of vibration absorption. The first involves an active tuning of an absorber for spectral and spatial variations. The second contribution is a set of generalized design guidelines for such absorber operations. “Spectral” tuning handles time-varying excitation frequencies, while “spatial” tuning treats the real-time variations in the desired location of suppression. Both objectives, however, must be achieved using active control and without physically altering the system components to ensure practicality. Spatial tuning is inspired by the concept of “noncollocated vibration absorption,” for which the absorber location is different from the point of suppression. This concept is relatively under-developed in the literature, mainly because it requires the use of part of the primary structure (PS) as the extended absorber—a delicate operation. Within this investigation, we employ the delayed resonator (DR)-based absorber, a hybrid concept with passive and active elements, to satisfy both tuning objectives. The presence of active control in the absorber necessitates an intriguing stability investigation of a time-delayed dynamics. For this subtask, we follow the well-established methods of frequency sweeping and D-subdivision. Example cases are also presented to corroborate our findings.

Real-time demand response of thermostatic load with active control

2018 ◽  
Vol 100 (4) ◽  
pp. 2649-2658 ◽  
Author(s):  
Ahmet Doğan ◽  
Mustafa Alçı
Keyword(s):  
Real Time ◽  
Active Control ◽  
Demand Response

scholarly journals Combining dielectrophoresis and computer vision for precise and fully automated single-cell handling and analysis

Lab on a Chip ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 4016-4020 ◽  
Author(s):  
Neus Godino ◽  
Felix Pfisterer ◽  
Tobias Gerling ◽  
Christian Guernth-Marschner ◽  
Claus Duschl ◽  
...  
Keyword(s):  
Image Processing ◽  
Computer Vision ◽  
Single Cell ◽  
Real Time ◽  
Active Control ◽  
Microfluidic Channel ◽  
Real Time Image Processing ◽  
Real Time Image ◽  
Cell Handling ◽  
Time Image

We employ real-time image processing in the active control of dielectrophoretic actuation to select, isolate and arrange individual cells in a microfluidic channel.

Data storage and real time observations at the Mexican Array Radio Telescope

2010 ◽  
Vol 46 (7) ◽  
pp. 968-972
Author(s):  
Gilberto A. Casillas-Pérez ◽  
Solai Jeyakumar ◽  
Armando Carrillo-Vargas ◽  
Ernesto Andrade ◽  
Americo González-Esparza ◽  
...  
Keyword(s):  
Real Time ◽  
Data Storage ◽  
Radio Telescope

scholarly journals Active Control and Adaptive Optics for Optical Interferometers

1989 ◽  
Vol 8 ◽  
pp. 565-566
Author(s):  
Fritz Merkle
Keyword(s):  
Control Systems ◽  
Real Time ◽  
Active Control ◽  
Adaptive Optics ◽  
Field Of View ◽  
Telescope Array ◽  
Large Unit ◽  
Long Baseline ◽  
Optical Interferometers ◽  
The Individual

Long baseline interferometry requires the full phasing of a telescope array. Especially for future arrays with large unit telescopes active control systems are mandatory. Adaptive optics can be applied for real-time phase compensation of the individual pupils due to atmospheric distortions. Additional to phasing of the individual pupils of independently mounted telescopes, the whole array has to be phased, including pupil position corrections due to pupil foreshortening and shift effects in order to reach a reasonable phased field-of-view.

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