An analysis of the survivability of sensor darts in impacts with trees.

Prentice, John K. (Sci-Tac, Inc., Boulder, CO.) ; Gardner, David Randall

Sandia National Laboratories

关键词: Probability;    Forests;    99 General And Miscellaneous//Mathematics, Computing, And Information Science;    Damage;    Trees;   

DOI  :  10.2172/923170
RP-ID  :  SAND2005-4330
RP-ID  :  AC04-94AL85000
RP-ID  :  923170

美国|英语

来源: UNT Digital Library

【 摘 要 】

A methodology was developed for computing the probability that the sensor dart for the 'Near Real-Time Site Characterization for Assured HDBT Defeat' Grand-Challenge LDRD project will survive deployment over a forested region. The probability can be decomposed into three approximately independent probabilities that account for forest coverage, branch density and the physics of an impact between the dart and a tree branch. The probability that a dart survives an impact with a tree branch was determined from the deflection induced by the impact. If a dart that was deflected so that it impacted the ground at an angle of attack exceeding a user-specified, threshold value, the dart was assumed to not survive the impact with the branch; otherwise it was assumed to have survived. A computer code was developed for calculating dart angle of attack at impact with the ground and a Monte Carlo scheme was used to calculate the probability distribution of a sensor dart surviving an impact with a branch as a function of branch radius, length, and height from the ground. Both an early prototype design and the current dart design were used in these studies. As a general rule of thumb, it we observed that for reasonably generic trees and for a threshold angle of attack of 5{sup o} (which is conservative for dart survival), the probability of reaching the ground with an angle of attack less than the threshold is on the order of 30% for the prototype dart design and 60% for the current dart design, though these numbers should be treated with some caution.