2,960 research outputs found

    Design and Test of a UAV Swarm Architecture over a Mesh Ad-Hoc Network

    Get PDF
    The purpose of this research was to develop a testable swarm architecture such that the swarm of UAVs collaborate as a team rather than acting as several independent vehicles. Commercial-off-the-shelf (COTS) components were used as they were low-cost, readily available, and previously proven to work with at least two networked UAVs. Initial testing was performed via software-in-the-loop (SITL) demonstrating swarming of three simulated multirotor aircraft, then transitioned to real hardware. The architecture was then tested in an outdoor nylon netting enclosure. Command and control (C2) was provided by software implementing an enhanced version of Reynolds’ flocking rules via an onboard companion computer, and UDP multicast messages over a W-Fi mesh ad-hoc network. Experimental results indicate a standard deviation between vehicles of two meters or less, at airspeeds up to two meters per second. This aligns with navigation instrumentation error, permitting safe operation of multiple vehicles within five meters of each other. Qualitative observations indicate this architecture is robust enough to handle more aircraft, pass additional sensor data, and incorporate different swarming algorithms and missions

    A Nonparametric Efficiency Analysis of Bean Producers from North and South Kivu

    Get PDF
    The purpose of this research is to determine how technically efficient small-scale producers are in two provinces (North and South Kivu) in the Democratic of Republic (DR) of Congo at producing two different varieties of beans: bush and climbing beans. In addition to calculating the efficiency scores, this research attempts to identify what producer and field characteristics affect these scores. We hypothesize that bean producers will be more productive than producers in South Kivu and that climbing bean producers will be more productive than bush bean producers. Technical efficiency is estimated using a nonparametric approach. A tobit model is used to examine the effect of producer and field characteristic on the efficiency score. On average, farms were 66% technically efficient. North Kivu bean producers and climbing bean producers have, on average, a higher technical efficiency score than their counterparts. Implications from this research suggest that there is room for improvement in the technical efficiency scores for producers in DR of Congo. Based on the results, it may be more productive to continue focusing on improving the yield and nutritional content of climbing beans.Production Economics, Production Economics,

    Sn-modification of Pt7/alumina model catalysts: Suppression of carbon deposition and enhanced thermal stability.

    Get PDF
    An atomic layer deposition process is used to modify size-selected Pt7/alumina model catalysts by Sn addition, both before and after Pt7 cluster deposition. Surface science methods are used to probe the effects of Sn-modification on the electronic properties, reactivity, and morphology of the clusters. Sn addition, either before or after cluster deposition, is found to strongly affect the binding properties of a model alkene, ethylene, changing the number and type of binding sites, and suppressing decomposition leading to carbon deposition and poisoning of the catalyst. Density functional theory on a model system, Pt4Sn3/alumina, shows that the Sn and Pt atoms are mixed, forming alloy clusters with substantial electron transfer from Sn to Pt. The presence of Sn also makes all the thermally accessible structures closed shell, such that ethylene binds only by π-bonding to a single Pt atom. The Sn-modified catalysts are quite stable in repeated ethylene temperature programmed reaction experiments, suggesting that the presence of Sn also reduces the tendency of the sub-nano-clusters to undergo thermal sintering

    Body Movement Syllabus - The City College of New York - Department of Theatre - Prof Timothy Allen

    Get PDF
    This course will explore three modules of learning. Anatomy and Psycho-Physical Centering, will explore two foundations: (1) the start of our research and practical application of the human anatomy in regards to how our body moves; and (2) your ability to tune into movement centers within the body by utilizing Chakra as a guiding study. Please note: Anatomy will be a continuous study throughout the entire semester. THE SECOND MODULE, Partnered Connection, will focus on partnering with lifts, counter-balances, falls, and rolls that will build to a partnering sequence of the tools presented. THE LAST MODULE, Global Archetypes, will explore archetypal dynamics in movement and how that connects to others, physical impulses, and given circumstances. This coursework aims to refine and expand proficiency in physical skills and the ability to embody and perform in an authentic, expressive, and unedited manner. â—Ź Application of the learned movement techniques will be assessed in various homework exercises, daily ensemble participation, quizzes, and three in-class performances

    Subsonic Ultra Green Aircraft Research: Phase II- Volume III-Truss Braced Wing Aeroelastic Test Report

    Get PDF
    This Test Report summarizes the Truss Braced Wing (TBW) Aeroelastic Test (Task 3.1) work accomplished by the Boeing Subsonic Ultra Green Aircraft Research (SUGAR) team, which includes the time period of February 2012 through June 2014. The team consisted of Boeing Research and Technology, Boeing Commercial Airplanes, Virginia Tech, and NextGen Aeronautics. The model was fabricated by NextGen Aeronautics and designed to meet dynamically scaled requirements from the sized full scale TBW FEM. The test of the dynamically scaled SUGAR TBW half model was broken up into open loop testing in December 2013 and closed loop testing from January 2014 to April 2014. Results showed the flutter mechanism to primarily be a coalescence of 2nd bending mode and 1st torsion mode around 10 Hz, as predicted by analysis. Results also showed significant change in flutter speed as angle of attack was varied. This nonlinear behavior can be explained by including preload and large displacement changes to the structural stiffness and mass matrices in the flutter analysis. Control laws derived from both test system ID and FEM19 state space models were successful in suppressing flutter. The control laws were robust and suppressed flutter for a variety of Mach, dynamic pressures, and angle of attacks investigated

    Impacts of a Community Supported Agriculture (CSA) Voucher Program on Food Lifestyle Behaviors: Evidence from an Employer-Sponsored Pilot Program

    Get PDF
    Community supported agriculture (CSA) programs have recently received attention for their potential to influence food lifestyle behaviors and health outcomes. We build on and expand inquiries into the relationship between CSA participation and behavior change by presenting the results from a controlled pilot study of first-time CSA shareholders. We offered 95 first-time shareholders a $200 voucher to participate in a CSA. Prior to and immediately following CSA participation, these shareholders completed a survey on food lifestyle behaviors. Using econometric analyses, we measured shareholder behavior changes against an 82 person control group. All participants were drawn from a pool of individuals involved in a university wellness program. From these analyses, we identified potential benefits and changes to shareholders in four unique categories: (1) fresh versus processed food consumption; (2) food prepared at home versus away from home; (3) food purchasing behavior and interest in nutrition; and (4) self-reported health outcomes. Changes within these categories and differences between test and control were more strongly realized in shareholders who reported lower than average health prior to the CSA. We conclude with a discussion about the potential of incentivized CSAs to serve as a novel preventative health intervention

    Passive, broadband and low-frequency suppression of laser amplitude noise to the shot-noise limit using hollow-core fibre

    Get PDF
    We use hollow-core fibre to preserve the spectrum and temporal profile of picosecond laser pulses in CBD to suppress 2.6 dB of amplitude noise at MHz noise frequencies, to within 0.01 dB of the shot-noise limit. We provide an enhanced version of the CBD scheme that concatenates circuits to suppress over multiple frequencies and over broad frequency ranges --- we perform a first demonstration that reduces total excess amplitude noise, between 2 - 6 MHz, by 85%. These demonstrations enable passive, broad-band, all-guided fibre laser technology operating at the shot-noise limit.Comment: 8 pages, 8 figure

    Subsonic Ultra Green Aircraft Research

    Get PDF
    This report summarizes the Truss Braced Wing (TBW) work accomplished by the Boeing Subsonic Ultra Green Aircraft Research (SUGAR) team, consisting of Boeing Research and Technology, Boeing Commercial Airplanes, General Electric, Georgia Tech, Virginia Tech, NextGen Aeronautics, and Microcraft. A multi-disciplinary optimization (MDO) environment defined the geometry that was further refined for the updated SUGAR High TBW configuration. Airfoil shapes were tested in the NASA TCT facility, and an aeroelastic model was tested in the NASA TDT facility. Flutter suppression was successfully demonstrated using control laws derived from test system ID data and analysis models. Aeroelastic impacts for the TBW design are manageable and smaller than assumed in Phase I. Flutter analysis of TBW designs need to include pre-load and large displacement non-linear effects to obtain a reasonable match to test data. With the updated performance and sizing, fuel burn and energy use is reduced by 54% compared to the SUGAR Free current technology Baseline (Goal 60%). Use of the unducted fan version of the engine reduces fuel burn and energy by 56% compared to the Baseline. Technology development roadmaps were updated, and an airport compatibility analysis established feasibility of a folding wing aircraft at existing airports
    • …
    corecore