190 research outputs found

    Measuring Scaling Effects in Small Two-Stroke Internal Combustion Engines

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    As internal combustion (IC) engines decrease in displacement, their cylinder surface area to swept volume ratio increases. Examining power output of IC engines with respect to cylinder surface area to swept volume ratio shows that there is a dramatic change in power scaling trends at approximately 1.5 cm-1. At this size, thermal quenching and friction losses are expected to dominate , so power production and efficiency characteristics suffer. Furthermore, small IC engines (100cc displacement) have limited technical performance data compared to IC engines in larger size classes. Therefore, it is critical to establish accurate performance figures for a family of geometrically similar engines in the size class of approximately 1.5 cm-1 in order to better predict the phenomena that contribute to lower efficiencies in small ICEs. A series of three two stroke, single cylinder, spark ignited, air cooled, and carbureted IC engines were tested in this study. They had a displacement of 28cc, 55cc and 85cc corresponding to cylinder surface area to swept volume ratios of 1.81 cm-1, 1.46 cm-1, and 1.28 cm-1 respectively. The engines share design features like compression ratio, gas exchange port design, and scavenging metho

    Assessing the Spatial Accuracy of Applanix DSS\u3csup\u3eTM\u3c/sup\u3e Model-301 Sensor Stereo Imagery using a Survey GPS Ground Control Network

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    During the past decade, Geographic Information Systems (GISs) have become widely used in many disciplines and that has created demands for accurate high-resolution digital data, especially digital imagery. Photogrammetry has emerged as one of the most important disciplines employed in the collection of spatially related information for use in GIS databases, especially for terrestrial landscapes. This study assessed the horizontal and vertical accuracy of the Applanix Digital Sensor System (DSS ) 301 orthophotographs. The study area was located on the University of Arkansas at Monticello campus and included 950 acres. To assess the spatial accuracy of the DSS, 56 Ground Control Points (GCPs) were collected prior to image acquisition using Trimble Surveying grade 4700 Global Positioning Systems (GPS). The 28 stereo aerial photographs used to create the orthorectified mosaic were taken with the DSSâ„¢ 30I, with approximately a 15.24 cm pixel spatial resolution. The average horizontal Root Mean Square Error (RMSE) for the DSS\u27 mosaic was 0.212m using the GPS-aided Inertial Measurement Unit (IMU) and 0.194 m from the mosaic created using one GCP per photo with the IMU. The vertical RMSE was 0.371 m for the 2-meter DEM created from stereo imagery using only the IMU

    Arbon-14 Isotope Effects in the Decarboxylation of 2-benzoylpropionic Acid

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    Organic Chemistr

    Evaluation of juvenile hormone analogues as rodent feed-through insecticides for control of immature phlebotomine sandflies

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    The juvenile hormone analogues methoprene and pyriproxyfen were evaluated as rodent feed-through insecticides for control of immature stages of the sandfly Phlebotomus papatasi Scopoli (Diptera: Psychodidae). The development and survival of P. papatasi second-instar larvae fed faeces from Syrian hamsters, Mesocricetus auratus, that had been fed a diet containing methoprene (0, 9.788, 97.88 or 978.8 p.p.m.) or pyriproxyfen (0, 9.82, 98.2 or 982 p.p.m.) were evaluated. The faeces of methoprene-treated hamsters greatly reduced the percentage of larvae that pupated at all concentrations tested and prevented adult emergence at all but the lowest concentration (9.788 p.p.m.). Pyriproxyfen prevented both pupation and adult emergence at all concentrations tested. The results of this study suggest that a control strategy using rodent baits containing juvenile hormone analogues to control phlebotomine sandflies that live in rodent burrows and feed on rodent faeces may be possible. As rodent reservoirs and vectors of Leishmania major live in close association in many parts of the Middle East, control of the transmission of the agent of zoonotic cutaneous leishmaniasis may also be possible. © 2010 The Authors. Medical and Veterinary Entomology © 2010 The Royal Entomological Society

    Experimental evidence of a natural parity state in 26^{26}Mg and its impact to the production of neutrons for the s process

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    We have studied natural parity states in 26^{26}Mg via the 22^{22}Ne(6^{6}Li,d)26^{26}Mg reaction. Our method significantly improves the energy resolution of previous experiments and, as a result, we report the observation of a natural parity state in 26^{26}Mg. Possible spin-parity assignments are suggested on the basis of published γ\gamma-ray decay experiments. The stellar rate of the 22^{22}Ne(α\alpha,γ\gamma)26^{26}Mg reaction is reduced and may give rise to an increase in the production of s-process neutrons via the 22^{22}Ne(α\alpha,n)25^{25}Mg reaction.Comment: Published in PR

    Canine Visceral Leishmaniasis, United States and Canada, 2000–2003

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    Foxhounds infected with Leishmania spp. were found in 18 states and 2 Canadian provinces

    Smoke, curtains and mirrors: the production of race through time and title registration

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    This article analyses the temporal effects of title registration and their relationship to race. It traces the move away from the retrospection of pre-registry common law conveyancing and toward the dynamic, future-oriented Torrens title registration system. The Torrens system, developed in early colonial Australia, enabled the production of ‘clean’, fresh titles that were independent of their predecessors. Through a process praised by legal commentators for ‘curing’ titles of their pasts, this system produces indefeasible titles behind its distinctive ‘curtain’ and ‘mirror’, which function similarly to magicians’ smoke and mirrors by blocking particular realities from view. In the case of title registries, those realities are particular histories of and relationships with land, which will not be protected by property law and are thus made precarious. Building on interdisciplinary work which theorises time as a social tool, I argue that Torrens title registration produces a temporal order which enables land market coordination by rendering some relationships with land temporary and making others indefeasible. This ordering of relationships with land in turn has consequences for the human subjects who have those relationships, cutting futures short for some and guaranteeing permanence to others. Engaging with Renisa Mawani and other critical race theorists, I argue that the categories produced by Torrens title registration systems materialise as race
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