Propagation Time Correction on Earth's Orbital Motion for Two-way Satellite Time and Frequency Transfer

2017 ◽  
Author(s):  
Wen-Hung Tseng
Keyword(s):  
Orbital Motion ◽  
Propagation Time ◽  
Time Correction ◽  
Frequency Transfer

scholarly journals Temporal Imaging CeBr3 Compton Camera: A New Concept for Nuclear Decommissioning and Nuclear Waste Management

2018 ◽  
Vol 170 ◽  
pp. 06003 ◽  
Author(s):  
A. Iltis ◽  
H. Snoussi ◽  
L. Rodrigues de Magalhaes ◽  
M.Z. Hmissi ◽  
C. Tata Zafiarifety ◽  
...  
Keyword(s):  
Waste Management ◽  
Gamma Ray ◽  
High Energy ◽  
High Temporal Resolution ◽  
Time Of Arrival ◽  
Propagation Time ◽  
Compton Camera ◽  
Nuclear Decommissioning ◽  
Energy Gamma ◽  
Time Correction

During nuclear decommissioning or waste management operations, a camera that could make an image of the contamination field and identify and quantify the contaminants would be a great progress. Compton cameras have been proposed, but their limited efficiency for high energy gamma rays and their cost have severely limited their application. Our objective is to promote a Compton camera for the energy range (200 keV – 2 MeV) that uses fast scintillating crystals and a new concept for locating scintillation event: Temporal Imaging. Temporal Imaging uses monolithic plates of fast scintillators and measures photons time of arrival distribution in order to locate each gamma ray with a high precision in space (X,Y,Z), time (T) and energy (E). This provides a native estimation of the depth of interaction (Z) of every detected gamma ray. This also allows a time correction for the propagation time of scintillation photons inside the crystal, therefore resulting in excellent time resolution. The high temporal resolution of the system makes it possible to veto quite efficiently background by using narrow time coincidence (< 300 ps). It is also possible to reconstruct the direction of propagation of the photons inside the detector using timing constraints. The sensitivity of our system is better than 1 nSv/h in a 60 s acquisition with a 22Na source. The project TEMPORAL is funded by the ANDRA/PAI under the grant No. RTSCNADAA160019.

High speed interferometric device for real-time correction of aero-optic effects

1995 ◽  
Author(s):  
Rod Clark ◽  
John Karpinsky ◽  
Gregg Borek ◽  
Eric Johnson
Keyword(s):  
Real Time ◽  
High Speed ◽  
Time Correction

PROPAGATION OF THE BURNING WAVE IN A PULSED DETONATION COMBUSTOR OPERATING ON MIXTURES OF HEPTANE AND JET A-1 WITH AIR AND OXYGEN AT [O2/AIR] < 1

2020 ◽  
Author(s):  
M. S. ASSAD ◽  
◽  
O. G. PENYAZKOV ◽  
I. I. CHERNUHO ◽  
K. ALHUSSAN ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Combustion Wave ◽  
Equivalence Ratio ◽  
Pressure Sensors ◽  
Jet Fuel ◽  
Propagation Time ◽  
Burning Wave ◽  
Pulsed Detonation ◽  
Combustion Wave Propagation ◽  
Fuel Jet

This work is devoted to the study of the dynamics of combustion wave propagation in oxygen-enriched mixtures of n-heptane with air and jet fuel "Jet A-1" in a small-size pulsed detonation combustor (PDC) with a diameter of 20 mm and a length less than 1 m. Experiments are carried out after the PDC reaches a stationary thermal regime when changing the equivalence ratio (ϕ = 0.73-1.89) and the oxygen-to-air ratio ([O2/air] = 0.15-0.60). The velocity of the combustion wave is determined by measuring the propagation time of the flame front between adjacent pressure sensors that form measurement segements along the PDC.

Day-ahead Load Probabilistic Forecasting Based on Space-time Correction

2020 ◽  
Vol 13 ◽  
Author(s):  
Fei Jin ◽  
Xiaoliang Liu ◽  
Fangfang Xing ◽  
Guoqiang Wen ◽  
Shuangkun Wang ◽  
...  
Keyword(s):  
Short Term Memory ◽  
Northern China ◽  
Space Time ◽  
Load Prediction ◽  
Probabilistic Forecasting ◽  
Residual Distribution ◽  
Time And Space ◽  
Probability Prediction ◽  
Time Correction ◽  
Interval Coverage

Background : The day-ahead load forecasting is an essential guideline for power generating, and it is of considerable significance in power dispatch. Objective: Most of the existing load probability prediction methods use historical data to predict a single area, and rarely use the correlation of load time and space to improve the accuracy of load prediction. Methods: This paper presents a method for day-ahead load probability prediction based on space-time correction. Firstly, the kernel density estimation (KDE) is employed to model the prediction error of the long short-term memory (LSTM) model, and the residual distribution is obtained. Then the correlation value is used to modify the time and space dimensions of the test set's partial period prediction values. Results: The experiment selected three years of load data in 10 areas of a city in northern China. The MAPE of the two modified models on their respective test sets can be reduced by an average of 10.2% and 6.1% compared to previous results. The interval coverage of the probability prediction can be increased by an average of 4.2% and 1.8% than before. Conclusion: The test results show that the proposed correction schemes are feasible.

scholarly journals Two-Stage Water Jet Landing Point Prediction Model for Intelligent Water Shooting Robot

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2704
Author(s):  
Yunhan Lin ◽  
Wenlong Ji ◽  
Haowei He ◽  
Yaojie Chen
Keyword(s):  
Pitch Angle ◽  
Back Propagation ◽  
Water Jet ◽  
The State ◽  
Model Parameters ◽  
Propagation Time ◽  
Back Propagation Algorithm ◽  
Angle Error ◽  
Landing Point ◽  
Propagation Algorithm

In this paper, an intelligent water shooting robot system for situations of carrier shake and target movement is designed, which uses a 2 DOF (degree of freedom) robot as an actuator, a photoelectric camera to detect and track the desired target, and a gyroscope to keep the robot’s body stable when it is mounted on the motion carriers. Particularly, for the accurate shooting of the designed system, an online tuning model of the water jet landing point based on the back-propagation algorithm was proposed. The model has two stages. In the first stage, the polyfit function of Matlab is used to fit a model that satisfies the law of jet motion in ideal conditions without interference. In the second stage, the model uses the back-propagation algorithm to update the parameters online according to the visual feedback of the landing point position. The model established by this method can dynamically eliminate the interference of external factors and realize precise on-target shooting. The simulation results show that the model can dynamically adjust the parameters according to the state relationship between the landing point and the desired target, which keeps the predicted pitch angle error within 0.1°. In the test on the actual platform, when the landing point is 0.5 m away from the position of the desired target, the model only needs 0.3 s to adjust the water jet to hit the target. Compared to the state-of-the-art method, GA-BP (genetic algorithm-back-propagation), the proposed method’s predicted pitch angle error is within 0.1 degree with 1/4 model parameters, while costing 1/7 forward propagation time and 1/200 back-propagation calculation time.

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