1,489 research outputs found
Decision Analysis with Geographically Varying Outcomes: Preference Models and Illustrative Applications
Get PDFDRMI Working Paper SeriesThe series is intended to convey the preliminary results of [DRMI] ongoing research. The research described in these papers is preliminary and has not completed the usual review process for Institute publications. We welcome feedback from readers and encourage you to convey your comments and criticisms directly to the authors
Update on Engine Combustion Research at Sandia National Laboratories
Full text linkThe objectives of this paper are to describe the research efforts in diesel engine combustion at Sandia National Laboratories' Combustion Research Facility and to provide recent experimental results. We have four diesel engine experiments supported by the Department of Energy, Office of Heavy Vehicle Technologies: a one-cylinder version of a Cummins heavy-duty engine, a diesel simulation facility, a one-cylinder Caterpillar engine to evaluate combustion of alternative fuels, and a homogeneous-charge, compression ignition (HCCI) engine. Recent experimental results of diesel combustion research will be discussed and a description will be given of our HCCI experimental program and of our HCCI modeling work
Removing Silos: 3 Graduate Programs Working Together
Get PDFPoster presented at: the Innovations in Best Practices in School Counselor Preparation Conference, The University of Georgia, Athens, GA, 2016
Time-resolved gas temperatures in the oscillating turbulent flow of a pulse combustor tail pipe
Full text linkThe cyclic behavior of the gas temperature in the oscillating turbulent flow in a pulse combustor tail pipe was studied using two-line atomic fluorescence. In this flow, the oscillations result from an acoustic resonance, and have amplitudes of up to 5 times the mean velocity. Oscillation frequencies were varied from 67 to 101 Hz. Spatially resolved temperature measurements were made to within 400 [mu]m of the wall, providing cycle-resolved profiles of the temperature and the random temperature fluctuations. The combustor-cycle phase relationships among the gas temperature, random-temperature-fluctuation intensity, velocity, and combustion chamber pressure, are compared. Velocity field effects dominated the cyclic behavior of the gas temperature, over the effects of isentropic compressive heating and the convection of hot pockets of gas from the combustion chamber. Cycle-resolved profiles show the gas temperature to be constant across the tail pipe, except for a boundary layer region, at all times during the cycle. Although cyclic temperature oscillations of more than 200 K were observed, the thermal boundary layer was well developed at all times during the cycle. The gas temperature was greater than the wall temperature at all cycle times, unlike the reversing velocity field, indicating that Reynolds analogy between momentum and thermal transport is not valid in this flow. Time-resolved wall heat flux was also measured and its fundamental oscillation is found to be in phase with that of the gas temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28549/1/0000348.pd
Pegasus Simulator: An Isaac Sim Framework for Multiple Aerial Vehicles Simulation
Full text linkDeveloping and testing novel control and motion planning algorithms for
aerial vehicles can be a challenging task, with the robotics community relying
more than ever on 3D simulation technologies to evaluate the performance of new
algorithms in a variety of conditions and environments. In this work, we
introduce the Pegasus Simulator, a modular framework implemented as an NVIDIA
Isaac Sim extension that enables real-time simulation of multiple multirotor
vehicles in photo-realistic environments, while providing out-of-the-box
integration with the widely adopted PX4-Autopilot and ROS2 through its modular
implementation and intuitive graphical user interface. To demonstrate some of
its capabilities, a nonlinear controller was implemented and simulation results
for two drones performing aggressive flight maneuvers are presented. Code and
documentation for this framework are also provided as supplementary material
Gender Differences in Stress and Coping Among Adults Living in Hawai`i
Get PDFBackground and purpose. Stress has been recognized as a public health problem. However, little research has been done on gender differences in sources of stress and coping strategies in Hawaii. In this study, we hypothesized that: 1) women will report higher levels of stress than men; 2) women will report being stressed by family and health related stressors while men will report stress related to finances and work-related issues; 3) women will report using adaptive coping strategies more frequently while men will report using maladaptive and avoidance strategies more frequently; 4) there will be no gender differences in the readiness to use stress management strategies. Method. A statewide cross-sectional telephone-survey of 1518 participants was conducted during the spring and summer of 2006. Results. Women reported higher overall perceived stress levels, but there was no difference in the experienced social stressors and health stressors between genders. Men perceived more stress from personal factors. There were no gender differences in the perceived ability to cope with stress. However, women were more likely to use adaptive coping strategies, whereas men were more likely to use maladaptive and avoidance coping strategies. There were no significant gender differences in stages of change for stress management. Conclusion. Based on this study, interventions can be developed to help people better cope with stress. Interventions for women may focus on increasing the use of adaptive strategies such as praying and talking to friends and family, while interventions for men may introduce the use of adaptive coping strategies such as exercise and actively fighting causes of stress. This study shows that gender differences in stress levels and coping in Hawaii are similar to previous studies conducted on the mainland. More research into specific stressors and coping strategies may help tailor interventions that are more effective and comprehensive
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