23,305 research outputs found

    A route generator concept for aircraft onboard fault monitoring

    Get PDF
    Because of the increasingly complex environments in which the flight crews of commercial aviation aircraft must operate, a research effort is currently underway at NASA Langley Research Center to investigate the potential benefits of intelligent cockpit aids, and to establish guidelines for the application of artificial intelligence techniques to advanced flight management concepts. The segment of this research area that concentrates on automated fault monitoring and diagnosis requires that a reference frame exist, against which the current state of the aircraft may be compared to determine the existence of a fault. This paper describes a computer program which generates the position of that reference frame that specifies the horizontal flight route

    The impact of stochastic physics on climate sensitivity in EC-Earth

    Full text link
    Stochastic schemes, designed to represent unresolved sub-grid scale variability, are frequently used in short and medium-range weather forecasts, where they are found to improve several aspects of the model. In recent years, the impact of stochastic physics has also been found to be beneficial for the model's long term climate. In this paper, we demonstrate for the first time that the inclusion of a stochastic physics scheme can notably affect a model's projection of global warming, as well as its historical climatological global temperature. Specifically, we find that when including the 'stochastically perturbed parametrisation tendencies' scheme (SPPT) in the fully coupled climate model EC-Earth v3.1, the predicted level of global warming between 1850 and 2100 is reduced by 10% under an RCP8.5 forcing scenario. We link this reduction in climate sensitivity to a change in the cloud feedbacks with SPPT. In particular, the scheme appears to reduce the positive low cloud cover feedback, and increase the negative cloud optical feedback. A key role is played by a robust, rapid increase in cloud liquid water with SPPT, which we speculate is due to the scheme's non-linear interaction with condensation.Comment: Under review in Journal of Geophysical Research: Atmosphere

    Estimating European volatile organic compound emissions using satellite observations of formaldehyde from the Ozone Monitoring Instrument

    Get PDF
    Emission of non-methane Volatile Organic Compounds (VOCs) to the atmosphere stems from biogenic and human activities, and their estimation is difficult because of the many and not fully understood processes involved. In order to narrow down the uncertainty related to VOC emissions, which negatively reflects on our ability to simulate the atmospheric composition, we exploit satellite observations of formaldehyde (HCHO), an ubiquitous oxidation product of most VOCs, focusing on Europe. HCHO column observations from the Ozone Monitoring Instrument (OMI) reveal a marked seasonal cycle with a summer maximum and winter minimum. In summer, the oxidation of methane and other long-lived VOCs supply a slowly varying background HCHO column, while HCHO variability is dominated by most reactive VOC, primarily biogenic isoprene followed in importance by biogenic terpenes and anthropogenic VOCs. The chemistry-transport model CHIMERE qualitatively reproduces the temporal and spatial features of the observed HCHO column, but display regional biases which are attributed mainly to incorrect biogenic VOC emissions, calculated with the Model of Emissions of Gases and Aerosol from Nature (MEGAN) algorithm. These "bottom-up" or a-priori emissions are corrected through a Bayesian inversion of the OMI HCHO observations. Resulting "top-down" or a-posteriori isoprene emissions are lower than "bottom-up" by 40% over the Balkans and by 20% over Southern Germany, and higher by 20% over Iberian Peninsula, Greece and Italy. We conclude that OMI satellite observations of HCHO can provide a quantitative "top-down" constraint on the European "bottom-up" VOC inventories

    Screening High-z GRBs with BAT Prompt Emission Properties

    Get PDF
    Detecting high-z GRBs is important for constraining the GRB formation rate, and tracing the history of re-ionization and metallicity of the universe. Based on the current sample of GRBs detected by Swift with known redshifts, we investigated the relationship between red-shift, and spectral and temporal characteristics, using the BAT event-by-event data. We found red-shift trends for the peak-flux-normalized temporal width T90, the light curve variance, the peak flux, and the photon index in simple power-law fit to the BAT event data. We have constructed criteria for screening GRBs with high red-shifts. This will enable us to provide a much faster alert to the GRB community of possible high-z bursts.Comment: 4 pages, 4 figures, to be published in the proceedings of ''Gamma Ray Bursts 2007'', Santa Fe, New Mexico, November 5-

    Mapping isoprene emissions over North America using formaldehyde column observations from space

    Get PDF
    We present a methodology for deriving emissions of volatile organic compounds (VOC) using space-based column observations of formaldehyde (HCHO) and apply it to data from the Global Ozone Monitoring Experiment (GOME) satellite instrument over North America during July 1996. The HCHO column is related to local VOC emissions, with a spatial smearing that increases with the VOC lifetime. Isoprene is the dominant HCHO precursor over North America in summer, and its lifetime (≃1 hour) is sufficiently short that the smearing can be neglected. We use the Goddard Earth Observing System global 3-D model of tropospheric chemistry (GEOS-CHEM) to derive the relationship between isoprene emissions and HCHO columns over North America and use these relationships to convert the GOME HCHO columns to isoprene emissions. We also use the GEOS-CHEM model as an intermediary to validate the GOME HCHO column measurements by comparison with in situ observations. The GEOS-CHEM model including the Global Emissions Inventory Activity (GEIA) isoprene emission inventory provides a good simulation of both the GOME data (r2 = 0.69, n = 756, bias = +11%) and the in situ summertime HCHO measurements over North America (r2 = 0.47, n = 10, bias = −3%). The GOME observations show high values over regions of known high isoprene emissions and a day-to-day variability that is consistent with the temperature dependence of isoprene emission. Isoprene emissions inferred from the GOME data are 20% less than GEIA on average over North America and twice those from the U.S. EPA Biogenic Emissions Inventory System (BEIS2) inventory. The GOME isoprene inventory when implemented in the GEOS-CHEM model provides a better simulation of the HCHO in situ measurements than either GEIA or BEIS2 (r2 = 0.71, n = 10, bias = −10%)

    Maintained physical activity and physiotherapy in the management of distal upper limb pain – a protocol for a randomised controlled trial (the arm pain trial)

    Get PDF
    <b>Background</b><p></p> Distal upper limb pain (pain affecting the elbow, forearm, wrist, or hand) can be non-specific, or can arise from specific musculoskeletal disorders. It is clinically important and costly, the best approach to clinical management is unclear. Physiotherapy is the standard treatment and, while awaiting treatment, advice is often given to rest and avoid strenuous activities, but there is no evidence base to support these strategies. This paper describes the protocol of a randomised controlled trial to determine, among patients awaiting physiotherapy for distal arm pain, (a) whether advice to remain active and maintain usual activities results in a long-term reduction in arm pain and disability, compared with advice to rest; and (b) whether immediate physiotherapy results in a long-term reduction in arm pain and disability, compared with physiotherapy delivered after a seven week waiting list period.<p></p> <b>Methods/Design</b><p></p> Between January 2012 and January 2014, new referrals to 14 out-patient physiotherapy departments were screened for potential eligibility. Eligible and consenting patients were randomly allocated to one of the following three groups in equal numbers: 1) advice to remain active, 2) advice to rest, 3) immediate physiotherapy. Patients were and followed up at 6, 13, and 26 weeks post-randomisation by self-complete postal questionnaire and, at six weeks, patients who had not received physiotherapy were offered it at this time. The primary outcome is the proportion of patients free of disability at 26 weeks, as determined by the modified DASH (Disabilities of the Arm, Shoulder and Hand) questionnaire.<p></p> We hypothesise (a) that advice to maintain usual activities while awaiting physiotherapy will be superior than advice to rest the arm; and (b) that fast-track physiotherapy will be superior to normal (waiting list) physiotherapy. These hypotheses will be examined using an intention-to-treat analysis.<p></p> <b>Discussion</b><p></p> Results from this trial will contribute to the evidence base underpinning the clinical management of patients with distal upper limb pain, and in particular, will provide guidance on whether they should be advised to rest the arm or remain active within the limits imposed by their symptoms

    Stranded assets and the shipping industry

    Get PDF
    According to IMO forecasts, CO2 emissions from world shipping could double by the year 2050. Although shipping is in most cases the most efficient mode of transport per unit of transport supply, it is still heavily reliant on heavy fuel oil to power its propulsion. The IMO has introduced regulations to bring about reductions in the emissions of ships, including an Energy Efficiency Design Index which sets a mandatory CO2 intensity reduction target for new ships and imposing a sulphur regulation on ships operating in certain sea areas. At the same time, charterers are beginning to factor energy efficiency into their commercial decision-making through use of the EVDI (an approximation of EEDI). Exemplifying this trend, Cargill, Huntsman and UNIPEC UK publically announced in October 2012 that they would no longer charter the least efficient ships in the fleet. This regulatory environment, along with the uncertainty in energy prices and increased awareness of the industry’s carbon footprint, poses a threat to existing ships’ profitability and may result in certain ships becoming stranded assets. The objective of this paper is to identify the supply and demand-side risk factors contributing to existing ships becoming stranded assets, and to frame how an assessment could be carried out on the risk of stranded assets in the shipping industry

    Mitigating local over-fitting during single particle reconstruction with SIDESPLITTER

    Get PDF
    Single particle analysis has become a key structural biology technique. Experimental images are extremely noisy, and during iterative refinement it is possible to stably incorporate noise into the reconstruction. Such “over-fitting” can lead to misinterpretation of the structure and flawed biological results. Several strategies are routinely used to prevent over-fitting, the most common being independent refinement of two sides of a split dataset. In this study, we show that over-fitting remains an issue within regions of low local signal-to-noise, despite independent refinement of half datasets. We propose a modification of the refinement process through the application of a local signal-to-noise filter: SIDESPLITTER. We show that our approach can reduce over-fitting for both idealised and experimental data while maintaining independence between the two sides of a split refinement. SIDESPLITTER refinement leads to improved density, and can also lead to improvement of the final resolution in extreme cases where datasets are prone to severe over-fitting, such as small membrane proteins

    Prikaz knjige: Zorislav Kaleb - Djelovanje kaznene presude na parnični postupak /Vizura, Zagreb, 2008./

    Get PDF
    Nedavno je u izdanju nakladničke kuće Vizura objavljena knjiga mr. sc. Zorislava Kaleba, suca Kaznenog odjela Općinskog suda u Zagrebu, Djelovanje kaznene presude na parnični postupak s podnaslovom Vezanost parničnog suda za pravomoćnu presudu kaznenog suda. Knjiga Djelovanje kaznene presude na parnični postupak predstavlja autorov izra¬đeni i obranjeni magistarski rad na poslijediplomskom znanstvenom studiju iz trgovačkog prava i prava društava na Pravnom fakultetu Sveučilišta u Zagrebu dana 4. travnja 2006. godine na temu Vezanost parničnog suda za pravomoćnu presudu kaznenog suda pred Povjerenstvom koje su činili akademik Jakša Barbić, predsjednik Povjerenstva, prof. dr. se. Mihajlo Dika kao mentor, te prof. dr. se. Davor Krapac i dr. se. Branko Vukmir kao članovi Povjerenstva. Isti rad je autor u međuvremenu dijelom prilagodio radi objave kao monografije, a također je unio i izmjene koje su se u međuvremenu dogodile našem pozitivnom zakonodavstvu. U knjizi se obrađuje odnos između parničnog i kaznenog postupka, vezanost par¬ničnog suda za pravomoćnu osuđujuću presudu kaznenog suda po tužbi iz istog događaja, prejudicijelno djelovanje presude kaznenog suda na parnični postupak, djelovanje kaznene presude kao pravno relevantne činjenice u parničnom postupku, prekid postupka po od¬luci suda u parničnom postupku, donošenje pravomoćne kaznene presude kao razlog za ponavljanje parničnog postupka, te neki zaključni prijedlozi de legeferenda. Rad dijelom komparativno obrađuje istu materiju i u nekim drugim zakonodavstvima u opsegu koliko je to zanimljivo za našeg praktičara. Knjiga je rezultat dvogodišnjeg istraživanja autora prvenstveno odluka Županijskog suda u Zagrebu i Vrhovnog suda Republike Hrvatske, te potom i dostupnih odluka drugih domaćih i stranih sudova
    corecore