scholarly journals A Novel Scanning Method Applied to New-Style Solar Telescope Based on Autoguiding System

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Zhi-ming Song ◽  
Zhong-quan Qu
Keyword(s):  
Closed Loop ◽  
Special Structure ◽  
Field Of View ◽  
Optical Telescope ◽  
Fiber Array ◽  
Scanning Method ◽  
Scanning Step ◽  
Disturbance Suppression ◽  
Random Disturbances ◽  
Software And Hardware

To expand field of view (FOV) of telescope, the method of special scanning often is used, but, for some telescopes with special structure in optics and machine, the conventional scanning methods are unsuitable. This paper proposes a novel scanning method based on autoguiding system so as to expand the FOV of fiber array solar optical telescope (FASOT) in possession of the special structure in optics and machine. Meanwhile, corresponding experiments are conducted in the FASOT prototype, FASOT-1B, in order to demonstrate that, for both FASOT and FASOT-1B, the proposed scanning method is feasible. First of all, on the basis of the software and hardware characteristics of FASOT and FASOT-1B, the three key technologies related to the proposed scanning method are described: quickly locating and pointing the first scanning step, the closed-loop controlling of multistep scanning, and the disturbance suppression of every scanning step based on Kalman filter. Afterwards, experiments are conducted and corresponding results show that the proposed scanning method is robust for the random disturbances forced on every scanning step and able to meet the scanning requirement of both FASOT and FASOT-1B .

scholarly journals A Leukocyte image fast scanning based on max–min distance clustering

2016 ◽  
Vol 09 (06) ◽  
pp. 1650022
Author(s):  
Yapin Wang ◽  
Yiping Cao
Keyword(s):  
Low Power ◽  
High Power ◽  
Blood Smear ◽  
Human Peripheral Blood ◽  
Lower Proportion ◽  
Field Of View ◽  
Clustering Method ◽  
Scanning Method ◽  
Scanning Time ◽  
Almost All

A leukocyte image fast scanning method based on max-min distance clustering is proposed. Because of the lower proportion and uneven distribution of leukocytes in human peripheral blood, there will not be any leukocyte in lager quantity of the captured images if we directly scan the blood smear along an ordinary zigzag scanning routine with high power (100x) objective. Due to the larger field of view of low power (10x) objective, the captured low power blood smear images can be used to locate leukocytes. All of the located positions make up a specific routine, if we scan the blood smear along this routine with high power objective, there will be definitely leukocytes in almost all of the captured images. Considering the number of captured images is still large and some leukocytes may be redundantly captured twice or more, a leukocyte clustering method based on max–min distance clustering is developed to reduce the total number of captured images as well as the number of redundantly captured leukocytes. This method can improve the scanning efficiency obviously. The experimental results show that the proposed method can shorten scanning time from 8.0–14.0[Formula: see text]min to 2.5–4.0[Formula: see text]min while extracting 110 nonredundant individual high power leukocyte images.

scholarly journals A study of gamma-ray burst afterglows as they first come into view of the SwiftUltraviolet and Optical Telescope

2019 ◽  
Vol 488 (2) ◽  
pp. 2855-2863
Author(s):  
M J Page ◽  
S R Oates ◽  
M De Pasquale ◽  
A A Breeveld ◽  
S W K Emery ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Light Curves ◽  
Field Of View ◽  
Prompt Gamma ◽  
Optical Telescope ◽  
Gamma Ray Burst ◽  
Thick Shells ◽  
Temporal Indices ◽  
Rule Out

ABSTRACT We examine the emission from optically bright gamma-ray burst (GRB) afterglows, as the Ultraviolet and Optical Telescope (UVOT) on the Neil Gehrels Swift Observatory first begins observing, following the slew to target the GRB, while the pointing of the Swift satellite is still settling. We verify the photometric quality of the UVOT settling data using bright stars in the field of view. In the majority of cases, we find no problems with the settling exposure photometry, but in one case, we excise the first second of the exposure to mitigate a spacecraft attitude reconstruction issue, and in a second case, we exclude the first second of the exposure in which the UVOT photocathode voltage appears to be ramping up. Of a sample of 23 afterglows which have peak V magnitudes <16, we find that all are detected in the settling exposures, when Swift arrives on target. For nine of the GRBs, the UVOT settling exposure took place before the conclusion of the prompt gamma-ray emission. Five of these GRBs have well-defined optical peaks after the settling exposures, with rises of >0.5 mag in their optical light curves, and there is a marginal trend for these GRBs to have long T90. Such a trend is expected for thick-shell afterglows, but the temporal indices of the optical rises and the timing of the optical peaks appear to rule out thick shells.

scholarly journals KOOLS–IFU: Kyoto Okayama Optical Low-dispersion Spectrograph with optical-fiber Integral Field Unit

2019 ◽  
Vol 71 (5) ◽  
Author(s):  
Kazuya Matsubayashi ◽  
Kouji Ohta ◽  
Fumihide Iwamuro ◽  
Ikuru Iwata ◽  
Eiji Kambe ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Gamma Ray ◽  
Field Of View ◽  
Resolving Power ◽  
Optimal Conditions ◽  
Total Field ◽  
Fiber Array ◽  
Field Unit ◽  
Low Dispersion ◽  
Integral Field

Abstract Observations of transient objects, such as short gamma-ray bursts and electromagnetic counterparts of gravitational wave sources, require prompt spectroscopy. To carry out prompt spectroscopy, we have developed an optical-fiber integral field unit (IFU) and connected it with an existing optical spectrograph, KOOLS. KOOLS–IFU was mounted on the Okayama Astrophysical Observatory 188 cm telescope. The fiber core and cladding diameters of the fiber bundle are 100 μm and 125 μm, respectively, and 127 fibers are hexagonally close-packed in the sleeve of the two-dimensional fiber array. We conducted test observations to measure the KOOLS–IFU performance and obtained the following conclusions: (1) the spatial sampling is ${2{^{\prime\prime}_{.}}34}$$\, \pm \,$${0{^{\prime\prime}_{.}}05}$ per fiber, and the total field of view is ${30{^{\prime\prime}_{.}}4}$$\, \pm \,$${0{^{\prime\prime}_{.}}65}$ with 127 fibers; (2) the observable wavelength and the spectral resolving power of the grisms of KOOLS are 4030–7310 Å and 400–600, 5020–8830 Å and 600–900, 4160–6000 Å and 1000–1200, and 6150–7930 Å and 1800–2400, respectively; and (3) the estimated limiting magnitude is 18.2–18.7 AB mag during 30 min exposure under optimal conditions.

Dynamic Visual Servoing for a Quadrotor Using a Virtual Camera

2017 ◽  
Vol 05 (01) ◽  
pp. 1-17 ◽  
Author(s):  
Geoff Fink ◽  
Hui Xie ◽  
Alan F. Lynch ◽  
Martin Jagersand
Keyword(s):  
Visual Servoing ◽  
Closed Loop ◽  
Field Of View ◽  
Visual Features ◽  
Control Law ◽  
Asymptotically Stable ◽  
Globally Asymptotically Stable ◽  
Virtual Camera ◽  
Aerial Vehicle ◽  
Planar Target

This paper presents a dynamic image-based visual servoing (IBVS) control law for a quadrotor unmanned aerial vehicle (UAV) equipped with a single fixed on-board camera. The motion control problem is to regulate the relative position and yaw of the vehicle to a moving planar target located within the camera’s field of view. The control law is termed dynamic as it’s based on the dynamics of the vehicle. To simplify the kinematics and dynamics, the control law relies on the notion of a virtual camera and image moments as visual features. The convergence of the closed-loop is proven to be globally asymptotically stable for a horizontal target. In the case of nonhorizontal targets, we modify the control using a homography decomposition. Experimental and simulation results demonstrate the control law’s performance.

A novel off-axis scanning method for an enlarged ellipse cone-beam computed tomography field of view

2010 ◽  
Vol 37 (12) ◽  
pp. 6233-6239 ◽  
Author(s):  
Tianfang Li ◽  
Xiang Li ◽  
Yong Yang ◽  
Dwight E. Heron ◽  
M. Saiful. Huq
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Field Of View ◽  
Cone Beam ◽  
Scanning Method

scholarly journals Control of BLDC Motor using PV fed Bridgeless Single Switch SEPIC Converter

2019 ◽  
Vol 9 (1) ◽  
pp. 2575-2580
Keyword(s):  
Closed Loop ◽  
Control Technique ◽  
Bldc Motor ◽  
Cuk Converter ◽  
Brushless Dc ◽  
Conduction Loss ◽  
Bridge Rectifier ◽  
Software And Hardware ◽  
Inherent Nature ◽  
Domestic Appliances

Brushless DC (BLDC) motors are now widely used in many industrial and domestic applications due to their significant advantages in terms of size, weight, torque and efficiency against any other type of motor. Most of the domestic appliances including refrigerators, fans and washing machines use BLDC motors in them. Moreover, photovoltaic (PV) inverters are being installed in more houses than ever which in-turn make BLDC motors more suitable in home appliances and can be seen as imminent future. However, PV due to its inherent nature is intermittent in its operation and requires an efficient DC-DC converter to control its output for its smooth operation. This papers proposes a bridgeless single switch single ended primary inductance converter (SEPIC) converter which serves as a better alternative to Buck-Boost and Cuk converter as it eliminates use of diode bridge rectifier at front end and thus lowers the conduction loss. A closed loop speed control technique is also introduced for control of BLDC motor to make it more practical for various applications and is verified using MATLAB/Simulink and a hardware prototype using Arduino. Results obtained from software and hardware prove the usefulness of the proposed scheme.

A Sensitivity Based Iterative Approach for Tuning Damper Parameters in Combination With the Controller to Increase Closed Loop Performance

2014 ◽  
Author(s):  
C. A. M. Verbaan ◽  
P. C. J. N. Rosielle ◽  
M. Steinbuch
Keyword(s):  
Closed Loop ◽  
Optimization Procedure ◽  
Iterative Approach ◽  
Main Difficulty ◽  
Frequency Range ◽  
Plant Model ◽  
Motion System ◽  
Controller Gain ◽  
Disturbance Suppression ◽  
Stiffness And Damping

In motion systems, high controller gains are beneficial in order to suppress disturbances acting on the system. Low-damped non-rigid body (NRB) resonances usually limit this controller gain. The result is a bound on the maximum achievable sensitivity, i.e. the suppression of low frequent position disturbances. Robust Mass Dampers (RMD’s) with a relatively high damping value have shown to be able to increase the NRB damping over a broad frequency range. The main difficulty is to determine the stiffness and damping parameters for these damper mechanisms in order to optimize the closed loop performance of the motion system. This paper proposes a modulus margin based iterative optimization procedure which includes a plant model with dampers added and a PID+ type controller. The results are optimal damper parameters — stiffness and damping — in combination with an as high as possible controller gain, which result in an improved disturbance suppression at frequencies below the bandwidth and a faster setpoint tracking.

scholarly journals Retina-like Imaging and Its Applications: A Brief Review

2021 ◽  
Vol 11 (15) ◽  
pp. 7058
Author(s):  
Qun Hao ◽  
Yu Tao ◽  
Jie Cao ◽  
Mingyuan Tang ◽  
Yang Cheng ◽  
...  
Keyword(s):  
State Of The Art ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Field Of View ◽  
Large Field ◽  
Ghost Imaging ◽  
Time Performance ◽  
Software And Hardware ◽  
Eye Retina ◽  
Space Variant

The properties of the human eye retina, including space-variant resolution and gaze characters, provide many advantages for numerous applications that simultaneously require a large field of view, high resolution, and real-time performance. Therefore, retina-like mechanisms and sensors have received considerable attention in recent years. This paper provides a review of state-of-the-art retina-like imaging techniques and applications. First, we introduce the principle and implementing methods, including software and hardware, and describe the comparisons between them. Then, we present typical applications combined with retina-like imaging, including three-dimensional acquisition and reconstruction, target tracking, deep learning, and ghost imaging. Finally, the challenges and outlook are discussed to further study for practical use. The results are beneficial for better understanding retina-like imaging.

scholarly journals Optical telescope with 3.75 ◦ field of view and pre-aperture slewing mirror with observation area of 50 ◦ ×120 ◦ for the system of observation of day time asteroids (the SODA project)

2021 ◽  
pp. 60-67
Author(s):  
А.С. Шугаров ◽  
В.Е. Шмагин ◽  
А.И. Буслаева ◽  
Б.М. Шустов
Keyword(s):  
Distinctive Feature ◽  
Field Of View ◽  
Optical Scheme ◽  
Space System ◽  
Optical Telescope ◽  
Advantages And Disadvantages ◽  
Observation Area ◽  
Flat Mirror ◽  
Small Pixel

В работе предложена оптическая схема широкоугольного телескопа с полем зрения 3.75 ◦ и апертурой 30 см для космической системы обнаружения декаметровых астероидов (проект СОДА). Основная отличительная особенность телескопа - наличие предапертурного плоского зеркала, обеспечивающего область наведения 50 ◦ × 120 ◦ , время перенаведения между соседними площадками составит не более 3 с. Предложен современный КМОП детектор с мелким пикселем. В работе представлены области обзора телескопов проекта СОДА из точки Лагранжа L 1 при использовании двух, трех и четырех телескопов, кратко обсуждены преимущества и недостатки каждого из вариантов. We propose an optical scheme of a telescope with a field of view of 3.75 ◦ and 30 cm aperture for the space system for observation of decameter size asteroids (the SODA project). The main distinctive feature of this telescope is a pre-aperture flat mirror that provides an observation area of 50 ◦ ×120 ◦ and a repointing time between the adjacent fields of less than 3 s. A modern CMOS detector with a small pixel is proposed. Observable sky area when using 2, 3 and 4 telescopes are described. The advantages and disadvantages of each option are briefly discussed.

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