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Personal Knowledge Management for Scholars
No full textEach of us is bombarded each day with more information than we can possibly process. This makes creative and scholarly work extremely difficult. In this presentation, I share strategies for better managing this information, making it easier to find what you need when you need it, and to put that information to creative use
2017 Replicated Agronomic Cotton Evaluation(RACE) South, East and Central Regions of Texas
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A Flexible Tether Management Model for Heterogeneous Marsupial Robot Systems
No full textHeterogeneous marsupial robotic systems are systems comprised of two or more robots that collaborate and leverage the strengths of each other to complete missions. These systems consist of one dispensing agent that provides resources to one or more passenger agents. To exchange these resources, whether in the form of power or data, there must be a physical connection between the dispensing agent and each passenger agent, known as a tether. Tethers enable passenger agents to use large power supplies housed on the dispensing agent, which would otherwise be impractical or impossible to house on the passenger agents themselves. Additionally, tethers can provide bidirectional data communication between the dispensing agent and the passenger agent such that the sensing and computation capabilities of each component can be used in one system. Marsupial robot systems consisting of unmanned surface vehicles (USV) and unmanned aerial vehicles (UAV) are effective systems to dispatch in marine environments. These systems use the sensing capabilities of the UAV to explore more of an environment and the power capabilities of the USV to lengthen UAV flight times. The tether connected from the USV to the UAV changes length as the UAV changes positions. Maintaining a proper tether length is crucial to system efficacy. If the tether is too long, it is prone to catching on obstacles in the environment. If it is too short, it may limit the mobility of the UAV. Researchers have explored ways to maintain proper tether length, but also, the potential benefits of prioritizing slackness or tautness in the tension of the tether and the potential benefits that arise from either design choice. This paper proposes a tether management system that prioritizes consistency, reliability, and flexibility by meticulously maintaining a proper tether length while allowing for control over tether slackness and spool reactivity. It seeks to implement aspects of both the slacked and taut models. This system was implemented within a heterogeneous marsupial robot system, with its dispensing agent represented as a ground station and its passenger agent represented by the Duckiebot DB21J UGV. The hardware decisions and modifications for the spool, ground station, and DB21J are discussed in this paper, as well as the overall ROS workspace structure designed to maximize efficiency and data transfer. After implementation, the tether management system was then tested by running a series of trials with varying spool control and tether model parameter values, specifically slackness and control gain. In each of these trials, the DB21J drove in a square path in the environment, and the response of the spool was recorded in each trial. The data was used to determine the consistency of the system and its response to varying parameters. The conclusion drawn from observing the behavior of the tether management system is that the system is designed for consistency and flexibility in spool control and tether length. During trials, slackness and control gain were manually set. In the future, these values are meant to be modified based on environmental factors
Beyond TEX86: Evaluating Archaeal Evolution Coupled with Ocean and Climate Changes Using Tetraether Lipids
No full textArchaea, once thought to be limited to extreme environments, are one of the most ubiquitous life forms on Earth and play crucial roles in global biogeochemical cycles. Among marine archaea, ammonia-oxidizing archaea (AOA) are key autotrophic microbes that significantly influence global carbon and nitrogen cycles. These organisms can adjust membrane-spanning lipids in response to environmental stress, particularly water temperatures. Isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) are common archaeal lipids found in marine sediments. For the past two decades, paleoclimatologists have determined tens of thousands of GDGTs from marine sediments and used them as a proxy to reconstruct past ocean temperatures, most notably the temperature proxy TEX86 (TetraEther indeX of 86 carbon atoms). TEX86 proxy becomes an essential tool for SST reconstructions in deep geologic pasts because of its ubiquity and resistance to post-depositional changes. However, there is a significant gap in continuous TEX86 data coverage during the Cenozoic era, a period essential to understanding future climates. My doctoral research seeks to extend the use of GDGTs and TEX86 beyond their traditional role in SST reconstruction. Using various analytical tools and statistical methodologies, the objectives of this dissertation are to (i) create continuous, quality-controlled TEX86 records throughout the Cenozoic, (ii) develop a data-driven analytical framework to study the ecology and evolution of marine archaea through GDGT analysis, and (iii) establish a geochemical proxy that can trace past ocean (de)oxygenation by utilizing newly discovered GDGT compounds, referred to as overly branched GDGTs (OB-GDGTs). My research aims to improve our understanding of the distribution of GDGT in marine sediments throughout the Cenozoic, provide information on the ecology and evolution of marine AOA, and demonstrate the multiple applications of GDGT beyond their conventional role in temperature reconstruction. Ultimately, it aspires to contribute to a more comprehensive understanding of past climates and their relevance to future environmental dynamics through the perspective of tetraether lipids