306 research outputs found

    The Cordilleran Ice Sheet and the Glacial Geomorphology of Southern and Central British Colombia

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    This paper reviews the current state of knowledge about the Cordilleran Ice Sheet in southern and central British Columbia. Reconstructions of the ice sheet and the styles of ice expansion and déglaciation are based on extensive and varied glacigenic sediments and landforms that date from Late Wisconsinan (Fraser) Glaciation. Late-glacial lakes and sea level changes are also described and related to isostatic and eustatic effects. The timing of ice expansion and recession during Fraser Glaciation was markedly asymmetric: ice build-up commenced about 29 000 years BP, culminated between 14 500 and 14 000 years BP1 and déglaciation was largely completed by 11 500 years BP. Most of this interval appears to have been dominated by montane glaciation, which produced striking erosional landforms. A Cordilleran Ice Sheet existed from only about 19 000 to 13 500 years BP. An older glaciation, probably of Early Wisconsinan age, has been recognized from widespread exposures of drift that underlies Middle Wisconsinan non-glacial sediments. Pre-Wisconsinan drift is present near Vancouver. Drifts of late Tertiary to Middle Pleistocene age have been dated by association with volcanic sequences in the southern Coast Mountains and the central Interior, and by paleomagnetic studies in the southern Interior.On résume ici l'état des connaissances sur l'Inlandsis de la Cordillère du sud et du centre de la Colombie-Britannique. Les reconstitutions de l'inlandsis et les modes d'englaciation et de déglaciation sont fondés sur les formes et les sédiments glaciaires qui datent de la glaciation du Wisconsinien supérieur (Fraser). On décrit également les lacs tardiglaciaires et les changements du niveau marin en relation avec les conséquences sur les niveaux isostatique et eustatique. Les rythmes de la progression et du retrait glaciaire ont été tout à fait différents; la giaciation a commencé vers 29 000 BP, a connu son optimum entre 14 500 et 14 000 BP et la déglaciation était à toutes fins utiles terminée dès 11 500 BP. La plus grande partie de cette époque a été dominée par une glaciation de type alpin, qui a engendré des formes d'érosion remarquables. L'Inlandsis de la Cordillère n'a existé que de 19 000 à 13 500 BP. On a identifié une glaciation plus ancienne, probablement du Wisconsinien inférieur, à partir des affleurements répandus de dépôts glaciaires sous-jacents aux sédiments non glaciaires du Wisconsinien moyen. On a observé des dépôts glaciaires pré-wisconsiniens près de Vancouver. Les dépôts glaciaires datant du Tertiaire supérieur au Pleistocene moyen ont été datés par association aux séquences volcaniques du sud des montagnes Côtières et du centre de l'Intérieur et grâce à des études de paléomagnétisme menées dans le sud du système de l'Intérieur.Dieser Artikel gibt einen uberblick ûber den gegenwartigen Forschungsstand zur Kordilleren-Eisdecke im Sùden und im Zentrum von British Columbia. Die Rekonstruktionen der Eisdecke und der Art und Weise der Eisausdehnung und Enteisung stùtzen sich auf extensive und mannigfache glazigene Sedimente und Landformen, die aus der Spât-Wisconsin- (Fraser) Vereisung stammen. Spàtglaziale Seen und Meeresniveauwechsel werden auch beschrieben und in Beziehung zu isostatischen und eustatischen Auswirkungen gesetzt. Der zeitliche Ablauf der Eisausdehnung und des Eisrùckzugs wàhrend der Fraser-Vereisung war deutlich asymmetrisch : die Vereisung begann um etwa 29 000 Jahre v.u.Z., erreichte ihren Hôchststand zwischen 14 500 und 14 000 Jahren v.u.Z. und die Enteisung war weitgehend vollendet um 11 500 Jahre v.u.Z. Der grôfîte Tail dieses Zeitraums scheint von einer alpinen Vereisung beherrscht gewesen zu sein, welche eindrucksvolle Erosions-Landformen hervorbrachte. Eine Kordilleren-Eisdecke existierte nur von etwa 19 000 bis 13 500 Jahre v.u.Z. Eine altère Vereisung, môglicherweise aus dem frùhen Wisconsin konnte anhand ausgedehnter Anlagen von glazialen Ablagerungen, die sich unter nichtglazialen Sedimenten des mittleren Wiskonsin befinden, identifiziert werden. Abgelagerte Bildungen aus dem Spàttertiâr bis zum mittleren Pleistozân wurden in Verbindung mit vulkanischen Sequenzen in den Bergen der Sùdkùste und dem zentralen Landesinnern und mittels palàomagnetischen Studien im sûdlichen Landesinnern datiert

    Changing the CIS Academic Culture: Using Senior Design Projects to Unify the Curriculum

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    Recently we initiated an effort to create a synergistic relationship between the senior design sequence and the sophomore software engineering course that resulted in a cultural change to our CIS academic community. Because of the enthusiastic response from students and faculty, we are extending this initiative to generate early interest among freshman and sophomore majors for electives in artificial intelligence and decision support. With hardware acquisitions obtained through an Instrumentation Laboratory Improvement (ILI) grant from the National Science Foundation, teams in the Senior Projects capstone sequence are preparing projects that will be employed in early courses in the curriculum. The projects will be used to provide students with insight about each of the elective areas of the curriculum through demonstrations and activities. This paper describes the five project initiatives and how the projects will be employed to generate interest in the elective areas

    Potential formulation of the dispersion relation for a uniform, magnetized plasma with stationary ions in terms of a vector phasor

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    The derivation of the helicon dispersion relation for a uniform plasma with stationary ions subject to a constant background magnetic field is reexamined in terms of the potential formulation of electrodynamics. Under the same conditions considered by the standard derivation, the nonlinear self-coupling between the perturbed electron flow and the potential it generates is addressed. The plane wave solution for general propagation vector is determined for all frequencies and expressed in terms of a vector phasor. The behavior of the solution as described in vacuum units depends upon the ratio of conductivity to the magnitude of the background field. Only at low conductivity and below the cyclotron frequency can significant propagation occur as determined by the ratio of skin depth to wavelength.Comment: 10 pages, 6 figures, major revision, final version, to appear in Po

    Can Water-Injected Turbomachines Provide Cost-Effective Emissions and Maintenance Reductions?

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    An investigation has been performed to evaluate the effect of water injection on the performance of the Air Force Research Laboratory (AFRL, Wright-Patterson Air Force Base (WPAFB)) experimental trapped vortex combustor (TVC) over a range of fuel-to-air and water-to-fuel ratios. Performance is characterized by combustor exit quantities: temperature and emissions measurements using rakes, and overall pressure drop, from upstream plenum to combustor exit. Combustor visualization is performed using gray-scale and color still photographs and high-frame-rate videos. A parallel investigation evaluated the performance of a computational fluid dynamics (CFD) tool for the prediction of the reacting flow in a liquid fueled combustor (e.g., TVC) that uses water injection for control of pollutant emissions and turbine inlet temperature. Generally, reasonable agreement is found between data and NO(x) computations. Based on a study assessing the feasibility and performance impact of using water injection on a Boeing 747-400 aircraft to reduce NO(x) emissions during takeoff, retrofitting does not appear to be cost effective; however, an operator of a newly designed engine and airframe might be able to save up to 1.0 percent in operating costs. Other challenges of water injection will be discussed

    The effects of feed budgeting, complete diet blending, and corn supplement blending on finishing pig growth performance in a commercial environment

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    A total of 808 pigs (PIC 337 x 1050, initially 78.4 ± 1.4 lb BW) were used to compare different feed-blending strategies for finishing pigs using the FeedPro system (Feedlogic Corp., Willmar, MN). There were 3 experimental treatments: (1) a standard-phase complete feed program, (2) blending a high- and low-lysine complete diet (curve), and (3) blending ground corn and a supplement. FeedPro is an integrated feed dispensing system that can deliver and blend 2 separate diets while dispensing. Treatment diets were fed over 4 phases (78 to 231 lb BW) with a common complete diet containing Paylean fed during the fifth phase. The 5 phases were from 78 to 115, 115 to 157, 157 to 191, 191 to 239, and 239 to 281 lb. Each treatment had 10 replicate pens and 26 to 27 pigs per pen. Overall (d 0 to 78), pigs phase-fed complete diets had greater (P < 0.01) ADG than pigs fed blended diets and tended to have greater (P < 0.07) ADG than those fed the ground corn-supplement blend. Pigs fed the blended diets had lower (P < 0.001) ADFI than pigs phase-fed complete diets or fed the corn-supplement blend. However, pigs fed blended diets had improved (P < 0.001) F/G compared to pigs phase-fed a ground corn-supplement blend and tended to have improved (P < 0.07) F/G compared to pigs fed standard-phase diets. Pigs fed standard-phase diets had heavier (P < 0.03) HCW than pigs fed the corn-supplement blend and tended to have heavier (P < 0.03) HCW than pigs fed diets on a lysine curve. However, there were no differences (P ≥ 0.11) in percentage yield, percentage lean, fat depth, or loin depth among treatments. There were no differences (P ≥ 0.11) in total revenue or income over feed costs (IOFC) across treatments. However, standard phase-fed pigs held a numerical advantage in total revenue, mainly driven by a heavier HCW over other treatments. Also, pigs fed a ground corn-supplement blend had numerically the lowest IOFC compared to other treatments. In conclusion, feeding using the FeedPro system is competitive with standard phase-fed diets on a net return basis, while feeding a ground corn-supplement blend adversely affected net returns

    Wide-field dynamic astronomy in the near-infrared with Palomar Gattini-IR and DREAMS

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    There have been a dramatic increase in the number of optical and radio transient surveys due to astronomical transients such as gravitational waves and gamma ray bursts, however, there have been a limited number of wide-field infrared surveys due to narrow field-of-view and high cost of infrared cameras, we present two new wide-field near-infrared fully automated surveyors; Palomar Gattini-IR and the Dynamic REd All-sky Monitoring Survey (DREAMS). Palomar Gattini-IR, a 25 square degree J-band imager that begun science operations at Palomar Observatory, USA in October 2018; we report on survey strategy as well as telescope and observatory operations and will also providing initial science results. DREAMS is a 3.75 square degree wide-field imager that is planned for Siding Spring Observatory, Australia; we report on the current optical and mechanical design and plans to achieve on-sky results in 2020. DREAMS is on-track to be one of the first astronomical telescopes to use an Indium Galium Arsenide (InGaAs) detector and we report initial on-sky testing results for the selected detector package. DREAMS is also well placed to take advantage and provide near-infrared follow-up of the LSST

    Evaluation of feed budgeting, complete diet blending, and corn-supplement blending on finishing-pig performance

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    A total of 283 pigs (PIC TR4 x 1050, initially 77.2 ± 1.4 lb BW) were used to compare phase feeding with blending finishing diets by using the FeedPro system (Feedlogic Corporation, Willmar, MN). There were 3 experimental treatments: (1) a standard 4-phase complete feed program, (2) blending high- and low-lysine complete diets over the entire experiment, and (3) blending ground corn and a separate complete supplement within each phase. FeedPro is an integrated feed dispensing system that can deliver and blend 2 separate diets while dispensing. The 4 phases were 77 to 120, 120 to 175, 175 to 221, and 221 to 278 lb. Each treatment had 12 replicate pens and 8 pigs per pen. Overall (77 to 278 lb), ADG and ADFI were similar (P \u3e 0.24) across treatments. However, pigs fed the ground corn-supplement blend had poorer (P \u3c 0.01) F/G than pigs fed diets blended in multiple phases and tended to have poorer (P \u3c 0.09) F/G than pigs fed the standard phase diets. There were no differences (P \u3e 0.70) in HCW, percentage yield, and loin depth across treatments. Pigs fed using phase feeding of the ground corn-supplement blend had greater (P \u3c 0.02) percentage lean and lower (P \u3c 0.04) fat depth than pigs fed using phase feeding of complete diets or diet blending. There were no (P \u3e 0.28) statistical differences in total revenue and income over feed costs (IOFC) across treatments. However, the highest IOFC was obtained from diet blending, which had a numeric advantage of 1.44to1.44 to 2.32/pig over other treatments. In conclusion, the FeedPro system blended separate complete diets and a ground corn-supplement combination without adversely affecting growth performance and carcass characteristics.; Swine Day, Manhattan, KS, November 18, 201

    An Early and Comprehensive Millimetre and Centimetre Wave and X-ray Study of SN 2011dh: a Non-Equipartition Blast Wave Expanding into a Massive Stellar Wind

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    Only a handful of supernovae (SNe) have been studied in multiwavelengths from the radio to X-rays, starting a few days after the explosion. The early detection and classification of the nearby Type IIb SN 2011dh/PTF 11eon in M51 provides a unique opportunity to conduct such observations. We present detailed data obtained at one of the youngest phase ever of a core-collapse SN (days 3–12 after the explosion) in the radio, millimetre and X-rays; when combined with optical data, this allows us to explore the early evolution of the SN blast wave and its surroundings. Our analysis shows that the expanding SN shock wave does not exhibit equipartition (ϵe/ϵB ∼ 1000), and is expanding into circumstellar material that is consistent with a density profile falling like R−2. Within modelling uncertainties we find an average velocity of the fast parts of the ejecta of 15 000 ± 1800 km s−1, contrary to previous analysis. This velocity places SN 2011dh in an intermediate blast wave regime between the previously defined compact and extended SN Type IIb subtypes. Our results highlight the importance of early (∼1 d) high-frequency observations of future events. Moreover, we show the importance of combined radio/X-ray observations for determining the microphysics ratio ϵe/ϵB

    What is the progenitor of the Type Ia SN 2014J?

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    We report the deepest radio interferometric observations of the closest Type Ia supernova in decades, SN 2014J, which exploded in the nearby galaxy M 82. These observations represent, together with radio observations of SNe 2011fe, the most sensitive radio studies of a Type Ia SN ever. We constrain the mass-loss rate from the progenitor system of SN 2014J lower than 7.0 × 10^(−10) M yr^(−1) (for a wind speed of 100 km s^(−1) ). Our deep upper limits favor a double-degenerate scenario–involving two WD stars–for the progenitor system of SN 2014J, as such systems have less circumstellar gas than our upper limits. By contrast, most single-degenerate scenarios, i.e., the wide family of progenitor systems where a red giant, main-sequence, or sub-giant star donates mass to a exploding white dwarf, are ruled out by our observations. The evidence from SNe 2011fe and 2014J points in the direction of a double-degenerate scenario for both

    The HIPASS Catalogue - II. Completeness, Reliability, and Parameter Accuracy

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    The HI Parkes All Sky Survey (HIPASS) is a blind extragalactic HI 21-cm emission line survey covering the whole southern sky from declination -90 to +25. The HIPASS catalogue (HICAT), containing 4315 HI-selected galaxies from the region south of declination +2, is presented in Meyer et al. (2004a, Paper I). This paper describes in detail the completeness and reliability of HICAT, which are calculated from the recovery rate of synthetic sources and follow-up observations, respectively. HICAT is found to be 99 per cent complete at a peak flux of 84 mJy and an integrated flux of 9.4 Jy km/s. The overall reliability is 95 per cent, but rises to 99 per cent for sources with peak fluxes >58 mJy or integrated flux > 8.2 Jy km/s. Expressions are derived for the uncertainties on the most important HICAT parameters: peak flux, integrated flux, velocity width, and recessional velocity. The errors on HICAT parameters are dominated by the noise in the HIPASS data, rather than by the parametrization procedure.Comment: Accepted for publication in MNRAS. 12 pages, 11 figures. Paper with higher resolution figures can be downloaded from http://hipass.aus-vo.or
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