321 research outputs found

    Design of a low-cost unmanned surface vehicle for swarm robotics research in laboratory environments

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    Swarm robotics is the study of groups of simple, typically inexpensive agents working collaboratively toward a common goal. Such systems offer several benefits over single-robot solutions: they are flexible, scalable, and robust to the failure of individual agents. The majority of existing work in this field has focused on robots operating in terrestrial environments but the benefits of swarm systems extend to applications in the marine domain as well. The current scarcity of marine robotics platforms suitable for swarm research is detrimental to progress in this field. Of the few that exist, no publicly available unmanned surface vehicles can operate in a laboratory environment; an indoor tank of water where the vessels, temperature, lighting, etc. can be observed and controlled at all times. Laboratory testing is a common intermediate step in the hardware validation of algorithms. This thesis details the design of the microUSV: a small, inexpensive, laboratory-based platform developed to fill this gap. The microUSV system was validated by performing laboratory testing of two algorithms: a waypoint-following controller and orbital retrieval. The waypoint-following controller was a simple PI controller implementation which corrects a vessel's speed and heading to seek predetermined goal positions. The orbital retrieval algorithm is a novel method for a swarm of unmanned surface vehicles to gather floating marine contaminants such as plastics. The vessels follow a circular path, orbiting around a central collection location and veer outwards to retrieve contaminants they detect outside the designated area. This method can potentially be used to cluster floating plastics together from a large region to facilitate cleanup

    Minor actinide waste disposal in deep geological boreholes

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    Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.Includes bibliographical references (leaves 63-65).The purpose of this investigation was to evaluate a waste canister design suitable for the disposal of vitrified minor actinide waste in deep geological boreholes using conventional oil/gas/geothermal drilling technology. The nature of minor actinide waste was considered, paying particular attention to nuclides whose decay energy and half lives were of relative significance to the minor actinide waste as a whole. Thermal Analysis was performed based on a reference borehole design, by Ian C. Hoag. The strategy of the thermal analysis is aimed at finding peak temperatures within the configuration, paying particular attention to the heat transfer under deep geological conditions in the air gap between the canister and the borehole. A first order economic analysis was made to compare the designed canister emplacement costs to that of intact spent fuel. The results of this analysis show that three minor actinide nuclides dominate heat generation after ten years cooling: Cm-244, Am-241, and Am-243 account for 97.5% of minor actinide decay heat. These three nuclides plus Np-237 account for 99% of the minor actinide mass. The thermal analysis was based on an irretrievable canister design, consisting of a 5 meter long synroc waste form, with minor actinides loaded to 1% wt, an outer radius of 15.8 cm and inner annular radius of 8.5 cm. Filling the annulus with a vitrified technetium and iodine waste form was found to be feasible using a multi-stage emplacement process. This process would only be required for three of the fifty boreholes because technetium and iodine have low heat generations after 10 years cooling. The suggested borehole waste form has a maximum centerline temperature of 349C. The costs of drilling boreholes to meet the demand of 100,000MT of PWR waste are estimated to be 3.5% of the current nuclear waste fund, or about $9.6/kg of original spent fuel.by Calvin Gregory Sizer.S.B

    Traceability for Food Safety and Quality Assurance: Mandatory Systems Miss the Mark

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    Traceability systems are record-keeping systems that are primarily used to help keep foods with different attributes separate from one another. When information about a particular attribute of a food product is systematically recorded from creation through marketing, traceability for that attribute is established. Recently, policy makers in many countries have begun weighing the usefulness of mandatory traceability for managing such diverse problems as the threat of bio-terrorism, country-of-origin labelling, mad cow disease, and identification of genetically engineered foods. The question before policymakers is, When is mandatory traceability a useful and appropriate policy choice?Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety,

    TRACEABILITY IN THE U.S. FOOD SUPPLY: ECONOMIC THEORY AND INDUSTRY STUDIES

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    This investigation into the traceability baseline in the United States finds that private sector food firms have developed a substantial capacity to trace. Traceability systems are a tool to help firms manage the flow of inputs and products to improve efficiency, product differentiation, food safety, and product quality. Firms balance the private costs and benefits of traceability to determine the efficient level of traceability. In cases of market failure, where the private sector supply of traceability is not socially optimal, the private sector has developed a number of mechanisms to correct the problem, including contracting, third-party safety/quality audits, and industry-maintained standards. The best-targeted government policies for strengthening firms' incentives to invest in traceability are aimed at ensuring that unsafe of falsely advertised foods are quickly removed from the system, while allowing firms the flexibility to determine the manner. Possible policy tools include timed recall standards, increased penalties for distribution of unsafe foods, and increased foodborne-illness surveillance.traceability, tracking, traceback, tracing, recall, supply-side management, food safety, product differentiation, Food Consumption/Nutrition/Food Safety, Industrial Organization,

    Fizzy: feature subset selection for metagenomics

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    BACKGROUND: Some of the current software tools for comparative metagenomics provide ecologists with the ability to investigate and explore bacterial communities using α- & β-diversity. Feature subset selection - a sub-field of machine learning - can also provide a unique insight into the differences between metagenomic or 16S phenotypes. In particular, feature subset selection methods can obtain the operational taxonomic units (OTUs), or functional features, that have a high-level of influence on the condition being studied. For example, in a previous study we have used information-theoretic feature selection to understand the differences between protein family abundances that best discriminate between age groups in the human gut microbiome. RESULTS: We have developed a new Python command line tool, which is compatible with the widely adopted BIOM format, for microbial ecologists that implements information-theoretic subset selection methods for biological data formats. We demonstrate the software tools capabilities on publicly available datasets. CONCLUSIONS: We have made the software implementation of Fizzy available to the public under the GNU GPL license. The standalone implementation can be found at http://github.com/EESI/Fizzy.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]

    The role of forensic anthropological techniques in identifying America\u27s war dead from past conflicts

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    The Scientific Analysis Directorate of the U.S. Department of Defense\u27s (DoD) Defense POW/MIA Accounting Agency (DPAA) is a unique entity within the U.S. Government. This agency currently houses the world\u27s largest, accredited skeletal identification laboratory in the world, in terms of the size of the scientific staff, global mission, and number of annual identifications. Traditional forensic anthropology is used for the formation of a biological profile (biological sex, stature, population affinity/ancestry, and age) as well as trauma and pathologies that may be compared with historical records and personnel files. Since World War II, various scientists associated with DoD have conducted base-line research in support of the identification of U.S. war dead, including, but not limited to, histology, the use of chest radiography and clavicle comparison, and statistical models to deal with commingling issues. The primary goal of the identification process of the Scientific Analysis Directorate is to use all available historical, field, and forensic methods to establish the most robust and defendable identification as scientifically and legally possible

    The Role of Forensic Anthropological Techniques in Identifying America\u27s War Dead from Past Conflicts

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    The Scientific Analysis Directorate of the U.S. Department of Defense\u27s (DoD) Defense POW/MIA Accounting Agency (DPAA) is a unique entity within the U.S. Government. This agency currently houses the world\u27s largest, accredited skeletal identification laboratory in the world, in terms of the size of the scientific staff, global mission, and number of annual identifications. Traditional forensic anthropology is used for the formation of a biological profile (biological sex, stature, population affinity/ancestry, and age) as well as trauma and pathologies that may be compared with historical records and personnel files. Since World War II, various scientists associated with DoD have conducted base-line research in support of the identification of U.S. war dead, including, but not limited to, histology, the use of chest radiography and clavicle comparison, and statistical models to deal with commingling issues. The primary goal of the identification process of the Scientific Analysis Directorate is to use all available historical, field, and forensic methods to establish the most robust and defendable identification as scientifically and legally possible

    Timescale of Petrogenetic Processes Recorded in the Mount Perkins Magma System, Northern Colorado River Extension Corridor, Arizona

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    The Miocene Mt. Perkins Pluton is a small composite intrusive body emplaced in the shallow crust as four separate phases during the earliest stages of crustal extension. Phase 1 (oldest) consists of isotropic hornblende gabbro and a layered cumulate sequence. Phase 2 consists of quartz monzonite to quartz monzodiorite hosting mafic microgranitoid enclaves. Phase 3 is composed of quartz monzonite and is subdivided into mafic enclave-rich zones and enclave-free zones. Phase 4 consists of aphanitic dikes of mafic, intermediate and felsic compositions hosting mafic enclaves. Phases 2-4 enclaves record significant isotopic disequilibrium with surrounding granitoid host rocks, but collectively enclaves and host rocks form a cogenetic suite exhibiting systematic variations in Nd-Sr-Pb isotopes that correlate with major and trace elements. Phases 2-4 record multiple episodes of magma mingling among cogenetic hybrid magmas that formed via magma mixing and fractional crystallization at a deeper crustal. The mafic end-member was alkali basalt similar to nearby 6-4 Ma basalt with enriched OIB-like trace elements and Nd-Sr-Pb isotopes. The felsic end-member was a subalkaline crustal-derived magma. Phase 1 isotropic gabbro exhibits elemental and isotopic compositional variations at relatively constant SiO2, suggesting generation of isotropic gabbro by an open-system process involving two mafic end-members. One end-member is similar in composition to the OIB-like mafic end-member for phases 2-4; the second is similar to nearby 11-8 Ma tholeiite basalt exhibiting low epsilon (sub Nd), and depleted incompatible trace elements. Phase 1 cumulates record in situ fractional crystallization of an OIB-like mafic magma with isotopic evidence of crustal contamination by partial melts generated in adjacent Proterozoic gneiss. The Mt Perkins pluton records a complex history in a lithospheric scale magma system involving two distinct mantle-derived mafic magmas and felsic magma sourced in the crust. Mixing and fractional crystallization of these magmas at various levels in the crust generated a suite of intermediate composition magmas. U-Pb zircon SHRIMP ages of phase 1 (15.7 +/- 0.2 Ma), phase 3 (15.8 +/- 0.2 Ma) and phase 4 (15.4 +/- 0.3 Ma) document a 100-300k year timescale for petrogenetic processes recorded in the Mt Perkins magma system

    On-Field Deployment and Validation for Wearable Devices

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    Wearable sensors are an important tool in the study of head acceleration events and head impact injuries in sporting and military activities. Recent advances in sensor technology have improved our understanding of head kinematics during on-field activities; however, proper utilization and interpretation of data from wearable devices requires careful implementation of best practices. The objective of this paper is to summarize minimum requirements and best practices for on-field deployment of wearable devices for the measurement of head acceleration events in vivo to ensure data evaluated are representative of real events and limitations are accurately defined. Best practices covered in this document include the definition of a verified head acceleration event, data windowing, video verification, advanced post-processing techniques, and on-field logistics, as determined through review of the literature and expert opinion. Careful use of best practices, with accurate acknowledgement of limitations, will allow research teams to ensure data evaluated is representative of real events, will improve the robustness of head acceleration event exposure studies, and generally improve the quality and validity of research into head impact injuries

    On-field deployment and validation for wearable devices

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    Wearable sensors are an important tool in the study of head acceleration events and head impact injuries in sporting and military activities. Recent advances in sensor technology have improved our understanding of head kinematics during on-field activities; however, proper utilization and interpretation of data from wearable devices requires careful implementation of best practices. The objective of this paper is to summarize minimum requirements and best practices for on-field deployment of wearable devices for the measurement of head acceleration events in vivo to ensure data evaluated are representative of real events and limitations are accurately defined. Best practices covered in this document include the definition of a verified head acceleration event, data windowing, video verification, advanced post-processing techniques, and on-field logistics, as determined through review of the literature and expert opinion. Careful use of best practices, with accurate acknowledgement of limitations, will allow research teams to ensure data evaluated is representative of real events, will improve the robustness of head acceleration event exposure studies, and generally improve the quality and validity of research into head impact injuries
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