An Insider’s Perspective on Observing Time Selection Committees

2006 ◽  
pp. 111-116 ◽  
Author(s):  
Jeffrey L. Linsky
Keyword(s):  
Time Selection

scholarly journals Detection of signals of moving objects based on the time selection method

2021 ◽  
Vol 66 (3) ◽  
pp. 335-342
Author(s):  
V. M. Artemiev ◽  
S. M. Kostromitsky ◽  
A. O. Naumov
Keyword(s):  
Moving Objects ◽  
Average Duration ◽  
Threshold Level ◽  
Selection Method ◽  
Probability Of Detection ◽  
False Alarms ◽  
Threshold Method ◽  
Detection Of Signals ◽  
Two Stages ◽  
Time Selection

To increase the efficiency of detecting moving objects in radiolocation, additional features are used, associated with the characteristics of trajectories. The authors assumed that trajectories are correlated, that allows extrapolation of the coordinate values taking into account their increments over the scanning period. The detection procedure consists of two stages. At the first, detection is carried out by the classical threshold method with a low threshold level, which provides a high probability of detection with high values of the probability of false alarms. At the same time uncertainty in the selection of object trajectory embedded in false trajectories arises. Due to the statistical independence of the coordinates of the false trajectories in comparison with the correlated coordinates of the object, the average duration of the first of them is less than the average duration of the second ones. This difference is used to solve the detection problem at the second stage based on the time-selection method. The obtained results allow estimation of the degree of gain in the probability of detection when using the proposed method.

Waypoint Constrained Multi-Phase Optimal Guidance of Spacecraft for Soft Lunar Landing

2019 ◽  
Vol 07 (02) ◽  
pp. 83-104 ◽  
Author(s):  
Kapil Sachan ◽  
Radhakant Padhi
Keyword(s):  
Selection Procedure ◽  
Landing Site ◽  
Terminal Point ◽  
Computationally Efficient ◽  
Soft Landing ◽  
Hard Constraints ◽  
Optimal Guidance ◽  
Safety Constraints ◽  
Multi Phase ◽  
Time Selection

A waypoint constrained multi-phase nonlinear optimal guidance scheme is presented in this paper for the soft landing of a spacecraft on the Lunar surface by using the recently developed computationally efficient Generalized Model Predictive Static Programming (G-MPSP). The proposed guidance ensures that the spacecraft passes through two waypoints, which is a strong requirement to facilitate proper landing site detection by the on-board camera for mission safety. Constraints that are required at the waypoints as well as at the terminal point include position, velocity, and attitude of the spacecraft. In addition to successfully meeting these hard constraints, the G-MPSP guidance also minimizes the fuel consumption, which is a very good advantage. An optimal final time selection procedure is also presented in this paper to facilitate minimization of fuel requirement to the best extent possible. Extensive simulation studies have been carried out with various perturbations to illustrate the effectiveness of the algorithm. Finally, processor-in-loop simulation has been carried out, which demonstrates the feasibility of on-board implementation of the proposed guidance.

scholarly journals Maximizing the Expected Duration of Owning a Relatively Best Object in a Poisson Process with Rankable Observations

2009 ◽  
Vol 46 (02) ◽  
pp. 402-414
Author(s):  
Aiko Kurushima ◽  
Katsunori Ano
Keyword(s):  
Poisson Process ◽  
Stopping Time ◽  
Fixed Time ◽  
Time Interval ◽  
Prior Density ◽  
Deterministic Equation ◽  
Fixed Time Interval ◽  
Unknown Number ◽  
Random Intensity ◽  
Time Selection

Suppose that an unknown number of objects arrive sequentially according to a Poisson process with random intensity λ on some fixed time interval [0,T]. We assume a gamma prior density G λ(r, 1/a) for λ. Furthermore, we suppose that all arriving objects can be ranked uniquely among all preceding arrivals. Exactly one object can be selected. Our aim is to find a stopping time (selection time) which maximizes the time during which the selected object will stay relatively best. Our main result is the following. It is optimal to select the ith object that is relatively best and arrives at some time s i (r) onwards. The value of s i (r) can be obtained for each r and i as the unique root of a deterministic equation.

scholarly journals Born at the Wrong Time: Selection Bias in the NHL Draft

PLoS ONE ◽  
2013 ◽  
Vol 8 (2) ◽  
pp. e57753 ◽  
Author(s):  
Robert O. Deaner ◽  
Aaron Lowen ◽  
Stephen Cobley
Keyword(s):  
Selection Bias ◽  
Time Selection
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