7,719 research outputs found

    Electrical power transmission and load analysis for a combine

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    Performance studies were made to determine design criteria for electrical couplings for combines. Electric motors were mounted on a Model 60, Allis- Chalmers combine so that the combine could be driven by a single motor, by combinations of more than one motor or by a standard pto coupling. Electrical energy was supplied to the motors from a tractor-mounted and -driven generator.https://lib.dr.iastate.edu/specialreports/1020/thumbnail.jp

    Systematic review of copper intrauterine contraception continuation in young nulliparous women based on intrauterine device type.

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    OBJECTIVES: No copper intrauterine device (IUD) type is known to better suit young nulliparous women who tend to experience higher rates of IUD discontinuation compared with their older parous counterparts. A systematic review to determine which IUDs have higher continuation rates in young nulliparous women was undertaken. DESIGN: Systematic review and meta-analyses of available evidence based on IUD type. DATA SOURCES: AMED, BNI, CINAHL, DARE, EMBASE, EMCARE, HMIC, MEDLINE, PsycINFO, PubMed, TRIP, and the Cochrane Library electronic databases were searched from inception to 11 May 2022; as well as the Bandolier, Medicines and Healthcare products Regulatory Agency, Faculty of Sexual and Reproductive Healthcare, Royal College of Obstetricians and Gynaecologists, Department of Health, National Institute for Health and Care Excellence, Scottish Intercollegiate Guidelines, WHO and Google Scholar websites. ELIGIBILITY CRITERIA: All studies on IUDs currently available in the UK or comparable (same design and size) to those available in the UK, involving nulliparous women of any age including those aged under 30. DATA EXTRACTION AND SYNTHESIS: Independently extracted data were assessed as low risk of bias using the Mixed Methods Appraisal Tool. Random effects meta-analyses of proportions were performed where data, including subgroups, were amenable to quantitative synthesis. Heterogeneity was reported using tau2 and I2 statistics, and sensitivity analyses were also performed. RESULTS: Nineteen studies involving 13 045 nulliparous women were included but the heterogeneity of participant ages, parity and IUD types made quantitative synthesis of outcome data in totality inappropriate. The highest continuation rate obtained was 91.02% (95% CI 88.01% to 93.64%) for the smaller TCu 380A at 12 months post insertion. CONCLUSIONS: Evidence for IUD use in young nulliparous women based on IUD type remains limited. Smaller sized IUD types appear better suited to this group of IUD users, however, more research is needed. PROSPERO REGISTRATION NUMBER: CRD42019120969

    Policy disconnect: A critical review of UK air quality policy in relation to EU and LAQM responsibilities over the last 20 years

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    © 2018 Elsevier Ltd This paper critically reviews United Kingdom (UK) air quality policy in relation to European and Local Air Quality Management (LAQM) responsibilities over the last 20 years. The arguments articulated in this paper highlight the gulf between national and local air quality management in the UK, including differences in legislation, legal responsibilities, scales of operation, monitoring and modelling requirements, exceedence reporting and action planning. It is argued that local authorities cannot be held responsible for the UK's failure to achieve the European Union (EU) nitrogen dioxide (NO2) limit values due to fundamental differences between local government responsibilities under LAQM and the UK compliance assessment reporting to the EU. Furthermore, unambitious and counterproductive national policies and the failure of EU light-duty vehicle type approval tests and Euro standards to reduce real-world emissions of nitrogen oxides (NOx) are the main reasons for continued NO2 limit value exceedences. This failure of EU and national air quality policies has effectively undermined local authority action to improve local air quality, resulting in delays in achieving the standards, wasted resources at local and national levels, and, ultimately, unnecessary loss of life and increased morbidity in the UK population. This paper concludes that the current emphasis that the UK government is placing on implementation of Clean Air Zones (CAZs) to achieve the Ambient Air Quality Directive (2008/50/EC) (AAQD), and avoid substantial fines imposed by the European Court of Justice (CJEU), is flawed. Based on the arguments presented in this paper, a series of recommendations is proposed for the European Union, the UK government, devolved administrations and local authorities

    Thermally Activated Magnetization and Resistance Decay during Near Ambient Temperature Aging of Co Nanoflakes in a Confining Semi-metallic Environment

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    We report the observation of magnetic and resistive aging in a self assembled nanoparticle system produced in a multilayer Co/Sb sandwich. The aging decays are characterized by an initial slow decay followed by a more rapid decay in both the magnetization and resistance. The decays are large accounting for almost 70% of the magnetization and almost 40% of the resistance for samples deposited at 35 oC^oC. For samples deposited at 50 oC^oC the magnetization decay accounts for 50\sim 50% of the magnetization and 50% of the resistance. During the more rapid part of the decay, the concavity of the slope of the decay changes sign and this inflection point can be used to provide a characteristic time. The characteristic time is strongly and systematically temperature dependent, ranging from 1\sim1x102s10^2 s at 400K to 3\sim3x105s10^5 s at 320K in samples deposited at 35oC35 ^oC. Samples deposited at 50 oC^oC displayed a 7-8 fold increase in the characteristic time (compared to the 35oC35 ^oC samples) for a given aging temperature, indicating that this timescale may be tunable. Both the temperature scale and time scales are in potentially useful regimes. Pre-Aging, Scanning Tunneling Microscopy (STM) reveals that the Co forms in nanoscale flakes. During aging the nanoflakes melt and migrate into each other in an anisotropic fashion forming elongated Co nanowires. This aging behavior occurs within a confined environment of the enveloping Sb layers. The relationship between the characteristic time and aging temperature fits an Arrhenius law indicating activated dynamics

    The Properties of Poor Groups of Galaxies: III. The Galaxy Luminosity Function

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    We obtain R-band photometry for galaxies in six nearby poor groups for which we have spectroscopic data, including 328 new galaxy velocities. For the five groups with luminous X-ray halos, the composite group galaxy luminosity function (GLF) is fit adequately by a Schechter function with Mstar = -21.6 +/- 0.4 + 5log h and alpha = -1.3 +/- 0.1. We also find that (1) the ratio of dwarfs to giants is significantly larger for the five groups with luminous X-ray halos than for the one marginally X-ray detected group, (2) the composite GLF for the luminous X-ray groups is consistent in shape with that for rich clusters, (3) the composite group GLF rises more steeply at the faint end than that of the field, (4) the shape difference between the field and composite group GLF's results mostly from the population of non-emission line galaxies, whose dwarf-to-giant ratio is larger in the denser group environment than in the field, and (5) the non-emission line dwarfs are more concentrated about the group center than the non-emission line giants. This last result indicates that the dwarfs and giants occupy different orbits (i.e., have not mixed completely) and suggests that the populations formed at a different times. Our results show that the shape of the GLF varies with environment and that this variation is due primarily to an increase in the dwarf-to-giant ratio of quiescent galaxies in higher density regions, at least up to the densities characteristic of X-ray luminous poor groups. This behavior suggests that, in some environments, dwarfs are more biased than giants with respect to dark matter. This trend conflicts with the prediction of standard biased galaxy formation models. (Abridged)Comment: 36 pages, AASLaTeX with 8 figures. Table 1 also available at http://atropos.as.arizona.edu/aiz/papers/all_grp_lf_ascii.dat.final . To appear in Ap

    Structure and triclustering in Ba-Al-O glass

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    Glass-forming ability in the (BaO) x(Al 2O 3) 1-x system (0≤x≤1) was investigated by using the containerless aerodynamic levitation and laser-heating method. The main glass-forming region was found to occur for 0.40(2) ≤x≤ 0.48(2), where there is insufficient oxygen to form an ideal network of corner-sharing AlO 4 tetrahedra in which the oxygen atoms are twofold coordinated, with another narrow glass-forming region at x = 0.62(2) around the eutectic composition. The glass corresponding to x = 0.4 was chosen for further investigation by using both neutron and x-ray diffraction, and a detailed atomistic model was built by applying a combination of molecular dynamics and reverse Monte Carlo methods. The results show a network structure based predominantly on corner-sharing tetrahedral AlO 4 motifs in which triclusters (OAl 3 units formed by three tetrahedral Al atoms sharing a common vertex) play an integral part, with as many as 21% of the oxygen atoms involved in these configurations. The barium ions bind to an average of 7.4 O atoms, most of which are twofold-coordinated bridging oxygen atoms. The larger size of barium compared to calcium narrows the range of glass-forming compositions in alkaline-earth aluminates such that the main glass-forming range corresponds to a regime in which an oxygen-deficient Al-O network is stabilized by the formation of triclusters

    Investigation of Control System and Display Variations on Spacecraft Handling Qualities for Docking with Stationary and Rotating Targets

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    This paper documents the investigation into the manual docking of a preliminary version of the Crew Exploration Vehicle with stationary and rotating targets in Low Earth Orbit. The investigation was conducted at NASA Langley Research Center in the summer of 2008 in a repurposed fixed-base transport aircraft cockpit and involved nine evaluation astronauts and research pilots. The investigation quantified the benefits of a feed-forward reaction control system thruster mixing scheme to reduce translation-into-rotation coupling, despite unmodeled variations in individual thruster force levels and off-axis center of mass locations up to 12 inches. A reduced rate dead-band in the phase-plane attitude controller also showed some promise. Candidate predictive symbology overlaid on a docking ring centerline camera image did not improve handling qualities, but an innovative attitude status indicator symbol was beneficial. The investigation also showed high workload and handling quality problems when manual dockings were performed with a rotating target. These concerns indicate achieving satisfactory handling quality ratings with a vehicle configuration similar to the nominal Crew Exploration Vehicle may require additional automation
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