10 research outputs found
Advances in Decentralized Single-Beacon Acoustic Navigation for Underwater Vehicles: Theory and Simulation
This paper reports the theory and implementation
of a decentralized navigation system that enables simultaneous
single-beacon navigation of multiple underwater vehicles. In
single-beacon navigation, each vehicle uses ranges from a single,
moving reference beacon in addition to its own inertial navigation
sensors to perform absolute localization and navigation. In this
implementation the vehicles perform simultaneous communication
and navigation using underwater acoustic modems, encoding
and decoding data within the acoustic broadcast. Vehicles calculate
range from the time of flight of asynchronous acoustic
broadcasts from the reference beacon. Synchronous clocks on
the reference beacon and the vehicles enable the measurement
of one-way travel-times, whereby the time of launch of the
acoustic signal at the reference beacon is encoded in the acoustic
broadcast and the time of arrival of the broadcast is measured
by each vehicle. The decentralized navigation algorithm, running
independently on each vehicle, is implemented using the
information form of the extended Kalman filter and has been
previously shown to yield results that are identical to a centralized
Kalman filter at the instant of each range measurement. We
summarize herein the architecture and design of the acoustic
communications (Acomms) system consisting of an underwater
acoustic modem, synchronous clock, and the software necessary
to run them, and salient results from the validation of the
decentralized information filter using a simulated data set.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86057/1/swebster-4.pd
Preliminary Deep Water Results in Single-Beacon One-Way-Travel-Time Acoustic Navigation for Underwater Vehicles
This paper reports the development and experimental
evaluation of a novel navigation system for underwater
vehicles that employs Doppler sonar, synchronous clocks, and
acoustic modems to achieve simultaneous acoustic communication
and navigation. The system reported herein, which is
employed to renavigate the vehicle in post-processing, forms the
basis for a vehicle-based real-time navigation system. Existing
high-precision absolute navigation techniques for underwater
vehicles are impractical over long length scales and lack
scalability for simultaneously navigating multiple vehicles. The
navigation method reported in this paper relies on a single
moving reference beacon, eliminating the requirement for
the underwater vehicle to remain in a bounded navigable
area. The use of underwater modems and synchronous clocks
enables range measurements based on one-way time-of-flight
information from acoustic data packet broadcasts. The acoustic
data packets are broadcast from the single, moving reference
beacon and can be received simultaneously by multiple vehicles
within acoustic range. We report experimental results from
the first deep-water evaluation of this method using data
collected from an autonomous underwater vehicle (AUV) survey
carried out in 4000 m of water on the southern Mid-Atlantic
Ridge. We report a comparative experimental evaluation of the
navigation fixes provided by the proposed synchronous acoustic
navigation system in comparison to navigation fixes obtained by
an independent conventional long baseline acoustic navigation
system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86040/1/swebster-7.pd
Toward a Platform-Independent Acoustic Communications and Navigation System for Underwater Vehicles
This paper presents a platform-independent
acoustic communication (Acomms) system that enables multiple
nodes (any combination of underwater vehicles, surface
ships, and fixed beacons) to simultaneously exchange data
and calculate inter-node ranges with O(1m) accuracy. The
Acomms system supports two types of communications: standard
asynchronous acoustic communication and synchronous
communication, which enables navigation based on inter-node
ranges derived from the one-way travel-times of acoustic
messages between nodes. The Acomms system hardware is
implemented with a dedicated software program, Linux host
computers, Woods Hole Oceanographic Institution (WHOI)
Micro-Modems, and precision reference clocks. The acoustic
communications software configures the modem, manages all
acoustic communication traffic, and acts as an interface between
the vehicle-specific software and the modems and clocks. The
software and related hardware have been installed on theWoods
Hole Oceanographic Institution vehicles Puma, Jaguar, and
Nereus, and deployed in sea trials in the North Pacific and
South Atlantic.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86048/1/swebster-8.pd
Important Attributes of a Behaviorally-Based Coaching Culture
Professional coaching is still considered an emerging field. Over the past 30 years, professional coaches and researchers have worked to further this profession by developing coaching competencies, exploring the nuances between various coaching modalities, and developing models to explain the role of coaching in organizations. There remains, however, a dearth of literature on coaching culture, including limited agreement on what it is and how it should look in an organization.
This study aims to establish agreement by investigating the confluence of coaching culture definitions and models present in industry and scholarly literature, and garnering input from a sample of professionals from diverse industries. This multiphase multimethod study provides an essential step, which has been largely missing in literature, establishing an empirically derived foundation of important behaviorally-based attributes from which coaching culture can be measured
ICD-10-CM-Based Definitions for Emergency Department Opioid Poisoning Surveillance: Electronic Health Record Case Confirmation Study
OBJECTIVES: Valid opioid poisoning morbidity definitions are essential to the accuracy of national surveillance. The goal of our study was to estimate the positive predictive value (PPV) of case definitions identifying emergency department (ED) visits for heroin or other opioid poisonings, using billing records with International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes.
METHODS: We examined billing records for ED visits from 4 health care networks (12 EDs) from October 2015 through December 2016. We conducted medical record reviews of representative samples to estimate the PPVs and 95% confidence intervals (CIs) of (1) first-listed heroin poisoning diagnoses (n = 398), (2) secondary heroin poisoning diagnoses (n = 102), (3) first-listed other opioid poisoning diagnoses (n = 452), and (4) secondary other opioid poisoning diagnoses (n = 103).
RESULTS: First-listed heroin poisoning diagnoses had an estimated PPV of 93.2% (95% CI, 90.0%-96.3%), higher than secondary heroin poisoning diagnoses (76.5%; 95% CI, 68.1%-84.8%). Among other opioid poisoning diagnoses, the estimated PPV was 79.4% (95% CI, 75.7%-83.1%) for first-listed diagnoses and 67.0% (95% CI, 57.8%-76.2%) for secondary diagnoses. Naloxone was administered in 867 of 1055 (82.2%) cases; 254 patients received multiple doses. One-third of all patients had a previous drug poisoning. Drug testing was ordered in only 354 cases.
CONCLUSIONS: The study findings suggest that heroin or other opioid poisoning surveillance definitions that include multiple diagnoses (first-listed and secondary) would identify a high percentage of true-positive cases