871 research outputs found

    A simulation of remote sensor systems and data processing algorithms for spectral feature classification

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    A computational model of the deterministic and stochastic processes involved in multispectral remote sensing was designed to evaluate the performance of sensor systems and data processing algorithms for spectral feature classification. Accuracy in distinguishing between categories of surfaces or between specific types is developed as a means to compare sensor systems and data processing algorithms. The model allows studies to be made of the effects of variability of the atmosphere and of surface reflectance, as well as the effects of channel selection and sensor noise. Examples of these effects are shown

    Earth feature identification for onboard multispectral data editing: Computational experiments

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    A computational model of the processes involved in multispectral remote sensing and data classification is developed as a tool for designing smart sensors which can process, edit, and classify the data that they acquire. An evaluation of sensor system performance and design tradeoffs involves classification rates and errors as a function of number and location of spectral channels, radiometric sensitivity and calibration accuracy, target discrimination assignments, and accuracy and frequency of compensation for imaging conditions. This model provides a link between the radiometric and statistical properties of the signals to be classified and the performance characteristics of electro-optical sensors and data processing devices. Preliminary computational results are presented which illustrate the editing performance of several remote sensing approaches

    Baseline LHC machine parameters and configuration of the 2015 proton run

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    This paper shows the baseline LHC machine parameters for the 2015 start-up. Many systems have been upgraded during LS1 and in 2015 the LHC will operate at a higher energy than before and with a tighter filling scheme. Therefore, the 2015 commissioning phase risks to be less smooth than in 2012. The proposed starting configuration puts the focus on feasibility rather than peak performance and includes margins for operational uncertainties. Instead, once beam experience and a better machine knowledge has been obtained, a push in ÎČ∗\beta^* and performance can be envisaged. In this paper, the focus is on collimation settings and reach in ÎČ∗\beta^*---other parameters are covered in greater depth by other papers in these proceedings.Comment: submitted for publication in a CERN yellow report (Proceedings of the LHC Performance Workshop - Chamonix 2014

    The importance of root interactions in field bean/triticale intercrops

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    To highlight the contribution of belowground interactions to biomass and N and P yields, field bean and triticale were grown in a P-poor soil as sole crops and as replacement intercrops at two N levels. The shoots were always in contact, while the roots of adjacent rows were free to interact or were completely separated. This allowed simultaneous testing the intraspecific and interspecific competition between rows, which to our knowledge has not been studied before. Root biomass, distribution in soil, morphometry, and functional traits were determined, together with the nodule number and biomass. The Land Equivalent Ratio for shoot biomass and N and P yield were higher than 1 when roots were in contact, and markedly lower when they were separated. This demonstrates the positive contribution of root interactions, which in field bean, consisted of increased root elongation without changes in biomass and nutrient status; in triticale, of increased N and P uptake eciency and reduced biomass partitioning to roots. The soil-plant processes underlying intercrop advantage led to complementarity in N sources with low N inputs and facilitated N and P uptake with high N inputs, which demonstrates that intercropping could be profitable in both low and high input agriculture

    Cover crop introduction in a Mediterranean maize cropping system. Effects on soil variables and yield

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    Cover crops (CCs) are able to affect subsequent crop behaviour by acting on many soil variables and affecting the dynamics of different ecological processes. This study aimed to investigate the effects of introducing CC in continuous-maize cropping systems within Mediterranean areas. The experimental site was located in Central Italy, on a sandy loam and the research activity was carried out over two years (2019–2020). The two cropping systems in comparison differed from each other in terms of the CC cultivation: TR (treated, with CC) and CO (control, without CC). In both years, we observed a significant reduction (p < 0.05) of soil nitrate and water content for the TR system. In the shallowest layer (0–30 cm), nitrate content was reduced by up 80% and 65% (July 2019 and 2020), whereas soil moisture showed decreases ranging from 13% (July 2019) to 34% (May 2019). In 2019, the TR-maize (Zea mays L.) yield was statistically lower than CO (443 g dm m2), whereas in 2020 the yields of the two systems resulted statistically equivalent. This different behaviour can be explained with the serious delay in the CC sowing occurred in 2019 (12 December). Conversely, an increase in the apparent remaining N in the soil (+140 and +133 kg N ha1 for 2019 and 2020, respectively) and in the C (carbon) inputs (+4.78 and +7.39 t dm ha1 of biomass) were pointed out for the TR system. The large use of inputs in Mediterranean maize cropping systems limited some of the benefits from CCs, but their suitability has to be evaluated by considering all the involved effects, some of which need a long time to become appreciable

    European emissions of HCFC-22 based on eleven years of high frequency atmospheric measurements and a Bayesian inversion method

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    HCFC-22 (CHClF2), a stratospherie ozone depleting substance and a powerful greenhouse gas, is the third most abundant anthropogenic halocarbon in the atmosphere. Primarily used in refrigeration and air conditioning systems, its global production and consumption have increased during the last 60 years, with the global increases in the last decade mainly attributable to developing countries. In 2007, an adjustment to the Montreal Protocol for Substances that Deplete the Ozone Layer called for an accelerated phase out of HCFCs, implying a 75% reduction (base year 1989) of HCFC production and consumption by 2010 in developed countries against the previous 65% reduction. In Europe HCFC-22 is continuously monitored at the two sites Mace Head (Ireland) and Monte Cimone (Italy). Combining atmospheric observations with a Bayesian inversion technique, we estimated fluxes of HCFC-22 from Europe and from eight macro-areas within it, over an 11-year period from January 2002 to December 2012, during which the accelerated restrictions on HCFCs production and consumption have entered into force. According to our study, the maximum emissions over the entire domain was in 2003 (38.2 +/- 4.7 Gg yr(-1)), and the minimum in 2012 (12.1 +/- 2.0 Gg yr(-1)); emissions continuously decreased between these years, except for secondary maxima in the 2008 and 2010. Despite such a decrease in regional emissions, background values of HCFC-22 measured at the two European stations over 2002-2012 are still increasing as a consequence of global emissions, in part from developing countries, with an average trend of ca 7.0 ppt yr(-1). However, the observations at the two European stations show also that since 2008 a decrease in the global growth rate has occurred. In general, our European emission estimates are in good agreement with those reported by previous studies that used different techniques. Since the currently dominant emission source of HCFC-22 is from banks, we assess the banks' size and their contribution to the total European emissions up to 2030, and we project a fast decrease approaching negligible emissions in the last five years of the considered period. Finally, inversions conducted over three month periods showed evidence for a seasonal cycle in emissions in regions in the Mediterranean basin but not outside it. Emissions derived from regions in the Mediterranean basin were ca. 25% higher in warmer months than in colder months. (C) 2015 The Authors. Published by Elsevier Ltd

    Nominal LHC Beam Instability Observations in the CERN Proton Synchrotron

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    The nominal LHC beam has been produced successfully in the CERN Proton Synchrotron since 2003. However, after having restarted the CERN PS in spring 2006, the LHC beam was set-up and observed to be unstable on the 26 GeV/c extraction flat top. An intensive measurement campaign was made to understand the instability and to trace its source. This paper presents the observations, possible explanations and the necessary measures to be taken in order to avoid this instability in the future

    LEP Operation and Performance with 100 GeV Colliding Beams

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    Luminosity production in LEP was extended to 101 GeV beam energy in 1999 and 104.4 GeV in 2000. The performance was continually optimised, resulting in 1999 peak and integrated luminosities higher than in any previous year of LEP operation. In particular, the beam-beam tune shift reached 0.083 per interaction point. This was achieved with the help of a faster luminosity monitoring, a new tune working point, a reduced design vertical dispersion and new dispersion and coupling optimisation tools. A higher beam rate from the injectors, a better injection efficiency, a faster ramp and a newly automated control of the horizontal damping partition number Jx maximised the time available for physics and thus contributed to the higher integrated luminosity

    LEP Performance at 91.5 GeV

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    The 1997 LEP collider run was the first year of the LEP2 program devoted to stable high luminosity running. The good performance of the LEP superconducting RF system allowed to run at beam energies of 91.5 GeV. In addition to the to usual optimisation procedures to minimise the vertical beam emittances, the horizontal beam sizes were reduced by increasing the horizontal damping partition number and reducing the betatron function at the interaction points. Vertical beam-beam tune shifts in excess of 0.05 were achieved with total beam currents of 5 mA. The total integrated luminosity of 73 pb-1 is the highest ever recorded in a single year of LEP operation
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