Caleb T. Phillips

Caleb T. Phillips
National Renewable Energy Laboratory | NREL · Computational Science

Ph.D.

About

77
Publications
29,460
Reads
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1,269
Citations
Introduction
Skills and Expertise
Additional affiliations
August 2014 - present
National Renewable Energy Laboratory
Position
  • Data Scientist
August 2013 - present
University of Colorado Boulder
Position
  • Research Assistant

Publications

Publications (77)
Article
Most of the existing traffic simulation packages require significant calibration work to be able to reflect reality. To evaluate special operations including emerging technologies, a microscopic simulation that tracks detailed interactions of all the elements of the traffic systems is usually needed. This type of simulation is usually computational...
Article
Full-text available
Background Sodium supplements are ubiquitous in endurance running, but their impact on performance has been subjected to much debate. The objective of the study was to assess the effect of sodium supplementation as a weight-based predictor of race performance in ultramarathon runners. Methods Prospective observational study during an 80 km (50 mi)...
Article
Emerging mobility technologies are changing the transportation system landscape. This is especially evident at airports, such as the Dallas-Fort Worth International Airport (DFW). Without careful analysis, these changes could lead to inefficient and costly airport operations. This paper presents a modeling framework that integrates travel mode enco...
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The High-Throughput Experimental Materials Database (HTEM-DB, htem.nrel.gov) is a repository of inorganic thin-film materials data collected during combinatorial experiments at the National Renewable Energy Laboratory (NREL). This data asset is enabled by NREL's Research Data Infrastructure (RDI), a set of custom data tools that collect, process, a...
Article
Background : Older populations are increasing and comprise a substantial portion of high-altitude travelers. Aging physiology may influence susceptibility to acute mountain sickness, though prior research remains inconclusive. The goal of this study was to investigate the relationship between increasing age and acute mountain sickness. Materials &...
Article
Airport ground access mode choice is distinct from everyday mode choice decisions, necessitating context-specific choice model estimation. Understanding airport ground access mode choice decisions is not only important for developing infrastructure planning strategies, but also for assessing the impacts of emerging modes on airport revenues, partic...
Article
The objective of this research is to reduce energy consumption from intra airport shuttle operations by optimizing routes and schedules, without compromising on passenger travel experience. To achieve this objective, we propose an optimization model that generates optimal airport shuttle routes for a given set of constraints and a discrete-event si...
Article
Airports are on the front line of significant innovations, allowing the movement of more people and goods faster, cheaper, and with greater convenience. As air travel continues to grow, airports will face challenges in responding to increasing passenger vehicle traffic, which leads to lower operational efficiency, poor air quality, and security con...
Article
Modern machine learning and autonomous experimentation schemes in materials science rely on accurate analysis of the data ingested by these models. Unfortunately, accurate analysis of the underlying data can be difficult, even for domain experts, complicating the training of the models intended to drive experiments. This is especially true when the...
Preprint
Full-text available
The High-Throughput Experimental Materials Database (HTEM-DB) is the endpoint repository for inorganic thin-film materials data collected during combinatorial experiments at the National Renewable Energy Laboratory (NREL). This unique data asset is enabled by the Research Data Infrastructure (RDI) - a set of custom data tools that collect, process,...
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Full-text available
Small, Elan, Nicholas Juul, David Pomeranz, Patrick Burns, Caleb Phillips, Mary Cheffers, and Grant S. Lipman. Predictive capacity of pulmonary function tests for acute mountain sickness. High Alt Med Biol. 00:000-000, 2021. Background: Pulmonary function as measured by spirometry has been investigated at altitude with heterogenous results, though...
Article
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Predictive maintenance and condition monitoring systems for wind turbines have seen increased adoption to minimize downtime, reducing operation and maintenance costs. On today’s wind power plants, the integrated supervisory control and data acquisition (SCADA) system provides low- frequency operational data that can be leveraged to quantify a wind...
Article
This article describes an interdisciplinary methodology to calculate the probability of failure for bearing axial cracking, the dominant failure mode in the intermediate and high-speed stages of many wind turbine gearboxes. This approach is mainly a physics-domain method with needed inputs from the data domain. The gearbox and bearing design along...
Article
Background Acetazolamide is the most common medication used for acute mountain sickness prevention, with speculation that a reduced dose may be as efficacious as standard dosing with fewer side effects. Methods This double-blind, randomized, controlled non-inferiority trial compared acetazolamide 62.5 mg twice daily to the standard dose acetazolam...
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Full-text available
Objective: Analyze the effect of sodium supplementation, hydration, and climate on dysnatremia in ultramarathon runners. Design: Prospective observational study. Setting: The 2017 80 km (50 mile) stage of the 250 km (150 mile) 6-stage RacingThePlanet ultramarathon in 2017 Chilean, Patagonian, and 2018 Namibian, Mongolian, and Chilean deserts....
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Background: Acetazolamide is the most common medication used for prevention of acute mountain sickness (AMS), usually administered the day or night before ascent. The objective of this study was to evaluate the efficacy of day of ascent dosing of acetazolamide for AMS prevention. Methods: Double-blind, randomized, controlled noninferiority trial o...
Preprint
Peripheral blood oxygen saturation Sp02 is a vital measure in healthcare. Modern off-the-shelf wrist-worn devices, such as the Apple Watch, FitBit, and Samsung Gear, have an onboard sensor called a pulse oximeter. While pulse oximeters are capable of measuring both Sp02 and heart rate, current wrist-worn devices use them only to determine heart rat...
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Background: Acute mountain sickness (AMS) is a common disease that may have a pulmonary component, as suggested by interstitial pulmonary edema quantified by the B-line score (BLS) on ultrasound (US). This subclinical pulmonary edema has been shown to increase with ascent to high altitude and AMS severity, but has not been prospectively associated...
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High-throughput experimental (HTE) techniques are an increasingly important way to accelerate the rate of materials research and development for many technological applications. However, there are very few publications on the reproducibility of the HTE results obtained across different laboratories for the same materials system, and on the associat...
Article
Background: Acute mountain sickness is a common occurrence for travel to high altitudes. Although previous studies of ibuprofen have shown efficacy for the prevention of acute mountain sickness, recommendations have been limited, as ibuprofen has not been compared directly with acetazolamide until this study. Methods: Before their ascent to 3810...
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Background: Climate change effect on flora and fauna has been scientifically documented, but the effect on North American venomous snakebites is unknown. The objectives were to examine Californian snakebite incidence and correlate with weather patterns and climate changes. Methods: A retrospective analysis of snakebites reported to the Californian...
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The use of advanced machine learning algorithms in experimental materials science is limited by the lack of sufficiently large and diverse datasets amenable to data mining. If publicly open, such data resources would also enable materials research by scientists without access to expensive experimental equipment. Here, we report on our progress towa...
Article
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As high-throughput combinatorial experimental methods become more common, the technical challenge is shifting from producing materials to dealing with increasingly large datasets. One of the most important metrics to determine suitability of semiconductor materials for various applications is the band gap. This paper discusses automated algorithms...
Conference Paper
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Path computing is a new paradigm that generalizes the edge computing vision into a multi-tier cloud architecture deployed over the geographic span of the network. Path computing supports scalable and localized processing by providing storage and computation along a succession of datacenters of increasing sizes, positioned between the client device...
Conference Paper
The use of unmanned aerial vehicles (UAV), or drones, has in recent years seen explosive growth due to lower costs and technology advances in mobile computing, batteries, sensors, and control systems. Drones are now used in a multitude of applications, from natural resource exploration, the film and entertainment industry, to urban surveillance, an...
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Abstract Background Despite concerns that non-steroidal antiinflammatory drugs (NSAIDs) contribute to acute kidney injury (AKI), up to 75% of ultramarathon runners ingest these during competition. The effect of NSAID on AKI incidence in ultramarathon runners is unclear. Methods Multisite randomised double-blind placebocontrolled trial in the Gobi,...
Article
Background Inhaled budesonide has been suggested as a novel prevention for acute mountain sickness. However, efficacy has not been compared to the standard acute mountain sickness prevention medication acetazolamide. Methods This double-blind, randomized, placebo-controlled trial compared inhaled budesonide to oral acetazolamide to placebo, starti...
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Introduction The focused assessment with sonography in trauma (FAST) exam is a critical diagnostic test for intraperitoneal free fluid (FF). Current teaching is that fluid accumulates first in Morison’s pouch. The goal of this study was to evaluate the “sub-quadrants” of traditional FAST views to determine the most sensitive areas for FF accumulati...
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Foraging provides decentralized access to food, medicines and other resources for communities across the planet. In urban environments, foraging can support social cohesion, food justice, and ecosystem restoration. Given growing urban populations and an increasing need for sustainable food systems in cities and surrounding areas, urban foraging is...
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Objective: To determine whether paper tape prevents foot blisters in multistage ultramarathon runners. Design: Multisite prospective randomized trial. Setting: The 2014 250-km (155-mile) 6-stage RacingThePlanet ultramarathons in Jordan, Gobi, Madagascar, and Atacama Deserts. Participants: One hundred twenty-eight participants were enrolled: 19 (15%...
Article
Objectives: We hypothesize that earlier operative intervention for acetabular fractures improves the probability of achieving an anatomic reduction. Design: Retrospective review SETTING:: Academic level I trauma center PATIENTS/PARTICIPANTS:: 650 acetabular fractures treated via ORIF between September 2001 and February 2014. Intervention: Acet...
Article
Full-text available
Objective: To determine whether paper tape prevents foot blisters in multistage ultramarathon runners. Design: Multisite prospective randomized trial. Setting: The 2014 250-km (155-mile) 6-stage RacingThePlanet ultramarathons in Jordan, Gobi, Madagascar, and Atacama Deserts. Participants: One hundred twenty-eight participants were enrolled:...
Article
Full-text available
Acute mountain sickness (AMS) affects 25%-70% of the tens of millions of high altitude travelers annually, with hypoxia and nocturnal desaturations as major contributing factors. This is the first double blind randomized placebo controlled trial to assess expiratory positive airway pressure (EPAP) for AMS prevention and nocturnal hypoxic events. He...
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Study Looking at End Expiratory Pressure for Altitude Illness Decrease (SLEEP-AID). High Alt Med Biol 00:000–000, 2015.—Acute mountain sickness (AMS) affects 25%–70% of the tens of millions of high altitude travelers annually, with hypoxia and nocturnal desaturations as major contributing factors. This is the first double blind randomized placebo c...
Article
Who gets to use radio spectrum, and when, where, and how? Scheduling (who, where, when) and system configuration (how) are fundamental problems in radio communication and wireless networking. Optimization decomposition based on Lagrangian relaxation of signal quality requirements provides a mathematical framework for solving this type of combined p...
Article
Full-text available
In this paper we study the simultaneous problems of food waste and hunger in the context of food (waste) rescue and redistribution as a means for mitigating hunger. To this end, we develop an empirical model that can be used in Monte Carlo simulations to study the dynamics of the underlying problem. Our model's parameters are derived from a data se...
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In this paper we provide a thorough and up to date survey of path loss prediction methods, spanning more than 60 years of fairly continuous research. These methods take a variety of approaches to modeling the signal attenuation between wireless transceivers: purely theoretical models, empirically fitted (often statistical) models, deterministic ray...
Conference Paper
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In this paper we present results from the first application of robust geostatistical modeling techniques to radio environment and coverage mapping of wireless networks. We perform our analysis of these methods with a case study mapping the coverage of a 2.5 GHz WiMax network at the University of Colorado, Boulder. Drawing from our experiences, we p...
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This paper applies the mathematics of chaos to the task of designing indoor rock-climbing routes. Chaotic variation has been used to great advantage on music and dance, but the challenges here are quite different, beginning with the representation. We present a formalized system for transcribing rock climbing problems and then describe a variation...
Article
We seek to provide practical lower bounds on the prediction accuracy of path loss models. We describe and implement 30 propagation models of varying popularity that have been proposed over the last 70 years. Our analysis is performed using a large corpus of measurements collected on production networks operating in the 2.4 GHz ISM, 5.8 GHz UNII, an...
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In this paper, we analyze the numerical stability of the popular Longley-Rice Irregular Terrain Model (ITM). This model is widely used to plan wireless networks and in simulation-validated research and hence its stability is of fundamental importance to the correctness of a large amount of work. We take a systematic approach by first porting the re...
Article
Full-text available
In this paper we study the simultaneous problems of food waste and hunger in the context of the possible solution of food (waste) rescue and redistribution. To this end, we develop an empirical model that can be used in Monte Carlo simulations to study the dynamics of the underlying problem. Our model's parameters are derived from a unique data set...
Conference Paper
Full-text available
Who gets to use radio spectrum, and when, where, and how? Many problems in traditional radio communication, wireless networking, and cognitive radio are variants of this question. Optimization decomposition based on Lagrangian relaxation of signal quality requirements provides a mathematical framework for solving this type of combined problem. This...
Conference Paper
Full-text available
In this paper we analyze the efficacy of basic path loss models at predicting median path loss in urban environments. We attempt to bound the practical error of these models and look at how they may hinder practical wireless applications, and in particular dynamic spectrum access networks. This analysis is made using a large set of measurements fro...
Article
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One method for improving wireless network throughput involves using directional antennas to increase signal gain and/or decrease interference. The physical layer models used in current networking simulators only minimally address the interaction of directional antennas and radio propagation. This paper compares the models found in popular simulatio...
Conference Paper
Full-text available
In this paper we make use of a large set of measurements from a production wireless network in rural New Zealand to analyze the performance of 28 path loss prediction models, published over the course of 60 years. We propose five metrics to determine the performance of each model. We show that the state of the art, even for the “simple” case of rur...
Conference Paper
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Phased array antennas enable the use of real-time beam-forming and null-steering to further increase control of signal strength and interference in wireless networks. Understanding the potential of this platform for both mesh and single-hop networks is becoming more important as smart antennas begin to appear in emerging networking standards. Prior...
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In this paper we apply chaotic systems to the task of sequence variation for the purpose of aiding humans in setting indoor rock climbing routes. This work expands on prior work where similar variations were used to assist in dance choreography and music composition. We present a formalization for transcription of rock climbing problems and a varia...
Article
Full-text available
Wireless networking optimizations are typically designed and evaluated independently of one another under the assumption that they can later be applied jointly. These works, however, do not provide sufficient information for future researchers and network administrators to determine which algorithms to combine, what order to combine them in, and ho...
Conference Paper
Full-text available
In the design of wireless networking protocols and systems, simulation has become the primary form of initial validation and performance evaluation. Hence, ensuring the realism of simulators and simulation methods is fundamental for simulated results to be interpretable. In this paper, we provide a simulation framework for infrastructure wireless n...