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Peter Domonkos - One of the best experts on this subject based on the ideXlab platform.

  • Homogenisation of temperature and precipitation time series with ACMANT3: method description and efficiency tests
    International Journal of Climatology, 2016
    Co-Authors: Peter Domonkos, John Coll
    Abstract:

    The development of Adapted Caussinus–Mestre Algorithm for homogenising Networks of Temperature series (ACMANT), one of the most successful Homogenisation methods tested by the European project COST ES0601 (HOME) has been continued. The third generation of the software package ‘ACMANT3’ contains six programmes for homogenising temperature values or precipitation totals. These incorporate two models of the annual cycle of temperature biases and Homogenisation either on a monthly or daily time scale. All ACMANT3 programmes are fully automatic and the method is therefore suitable for homogenising large datasets. This paper describes the theoretical background of ACMANT and the recent developments, which extend the capabilities, and hence, the application of the method. The most important novelties in ACMANT3 are: the ensemble pre-Homogenisation with the exclusion of one potential reference composite in each ensemble member; the use of ordinary kriging for weighting reference composites; the assessment of seasonal cycle of temperature biases in case of irregular-shaped seasonal cycles. ACMANT3 also allows for Homogenisation on the daily scale including for break timing assessment, gap filling and ANOVA application on the daily time scale. Examples of efficiency tests of monthly temperature Homogenisation using artificially developed but realistic test datasets are presented. ACMANT3 can be characterized by improved efficiency in comparison with earlier ACMANT versions, high missing data tolerance and improved user friendliness. Discussion concerning when the use of an automatic Homogenisation method is recommended is included, and some caveats in relation to how and when ACMANT3 should be applied are provided.

  • Efficiency evaluation for detecting inhomogeneities by objective Homogenisation methods
    Theoretical and Applied Climatology, 2011
    Co-Authors: Peter Domonkos
    Abstract:

    Evaluation and comparison of efficiencies of widely used objective Homogenisation methods (OHOMs) are presented relying on some test-datasets and efficiency measures. Problems related to the choice of efficiency measure, creation of appropriate test-datasets and use of OHOM parameterisation are discussed. The detection parts of the OHOMs are examined only. Power of detection, false alarm rate, detection skill and skill of linear trend estimation are calculated and compared for eight OHOMs and six test-datasets. Each test-dataset comprises 10,000 100 year-long artificially simulated time series. In the simplest test dataset, each time series contains one inhomogeneity (IH), while a structure of inhomogeneities that is similar to that of real central European temperature time series is included in the most complex simulated dataset. Distinct attention is given to OHOMs that contain (1) cutting algorithm, (2) semihierarchic algorithm, (3) direct detection of multiple IHs, (4) detection of change-point and trend-line shaped IHs. Results show that Caussinus–Mestre method and Multiple Analysis of Series for Homogenization are the most powerful tools in detecting and correcting IHs in climatic time series.

  • First results from the COST-HOME monthly benchmark dataset with temperature and precipitation data for testing Homogenisation algorithms
    The EGU General Assembly, 2010
    Co-Authors: Venema, Peter Domonkos, O. Mestre, Enric Aguilar, Ingeborg Auer, José Antonio Guijarro, G. Vertacnik, Tamás Szentimrey, Petr Stepanek, Pavel Zahradníček
    Abstract:

    As part of the COST Action HOME (Advances in Homogenisation methods of climate series: an integrated approach) a dataset was generated that serves as a benchmark for Homogenisation algorithms. Members of the Action and third parties have been invited to homogenise this dataset. The results of this exercise are analysed by the HOME Working Groups (WG) on detection (WG2) and correction (WG3) algorithms to obtain recommendations for a standard Homogenisation procedure for climate data. This talk will shortly describe this benchmark dataset and present first results comparing the quality of the about 25 contributions.

Liya Liu - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Homogenisation and storage time on surface and rheology properties of whipping cream
    Food Chemistry, 2012
    Co-Authors: Zhao Long, Mouming Zhao, Qiangzhong Zhao, Bao Yang, Liya Liu
    Abstract:

    Abstract The effects of Homogenisation pressure and storage time on the droplet characteristics, surface protein concentration and rheological properties of whipping cream were investigated in this work. The droplet size distribution was in a range of 0.120–17.378 μm when homogenised once, and 0.0794–3.802 μm when homogenised twice. With the increase in Homogenisation pressure, the mean droplet diameter shifted toward a smaller size and dispersion index. The Homogenisation pressure change from 20 to 50 MPa resulted in a reduction of the surface protein concentration. As the time increased, the surface protein concentration declined, and a higher pressure led to its decline to a lesser extent. All the emulsions exhibited a shear-thinning and gel-like behaviour with the elastic modulus higher than the viscous modulus. When increasing the Homogenisation pressure, the gel-like behaviour was more pronounced in both Homogenisation systems. The Herschel–Bulkley model was able to describe well the rheological characteristics.

Claire Blayo - One of the best experts on this subject based on the ideXlab platform.

  • Technological aspects and potential applications of (ultra) high-pressure Homogenisation
    Trends in Food Science & Technology, 2013
    Co-Authors: E. Dumay, Dominique Chevalier-lucia, Laetitia Picart-palmade, Amal Benzaria, Alvar Gràcia-julià, Claire Blayo
    Abstract:

    The present review concerns Homogenisation processing, and more particularly high-pressure Homogenisation. Recent developments in high-pressure technology and the design of new Homogenisation valves able to withstand pressures up to 350–400 MPa have indeed opened new opportunities to Homogenisation processing in the dairy, pharmaceutical and cosmetic industries. Homogenisers equipped with high-pressure valves or interaction chambers of different designs, and consequently different flow characteristics (laminar or turbulent flow, cavitation, impingement on solid walls, fluid jet collision) are available. The present review will more particularly concern piston-gap type high-pressure homogenisers equipped with specially designed HP-valves able to reach 300–400 MPa for ultra-high-pressure Homogenisation (UHPH). An overview of some recent UHPH studies will be summarised in the following sections including UHPH-induced microbial inactivation, characteristics of submicron emulsions and UHPH-induced protein structural changes and functionality.

Ladislav Čurda - One of the best experts on this subject based on the ideXlab platform.

  • Influence of processing and κ-carrageenan on properties of whipping cream
    Journal of Food Engineering, 2010
    Co-Authors: Renáta Kováčová, Jaroslav Květina, Ladislav Čurda
    Abstract:

    Abstract The aim of this work was to characterise the influence of ultra-high-temperature (UHT) treatment and high-pressure Homogenisation on functional properties of whipping cream (30% fat content) in relation to adding κ-carrageenan (0%, 0.02% and 0.04% in milk plasma). The determination of the particle size distribution, which was measured by laser diffraction and verified by microscopic observation, indicated that the diameter of fat globules decreased significantly by Homogenisation but clusters of small fat globules were produced before the carrageenan–casein micelles aggregates. The viscosity of cream was increased and the thixotropic behaviour was observed both by adding carrageenan and by Homogenisation. The Homogenisation significantly increased colloidal stability during storage and milk plasmas’ release was minimised in combination with carrageenan addition. The most influenced functional properties were: the whippability, which was significantly impaired by Homogenisation, and the stability of whipped foam, which was significantly improved with the increase of the carrageenan concentration.

Sheng Zhang - One of the best experts on this subject based on the ideXlab platform.

  • enhancement of anaerobic sludge digestion by high pressure homogenization
    Bioresource Technology, 2012
    Co-Authors: Sheng Zhang, Panyue Zhang, Guangming Zhang, Yuxua Zhang
    Abstract:

    To improve anaerobic sludge digestion efficiency, the effects of high-pressure homogenization (HPH) conditions on the anaerobic sludge digestion were investigated. The VS and TCOD were significantly removed with the anaerobic digestion, and the VS removal and TCOD removal increased with increasing the homogenization pressure and homogenization cycle number; correspondingly, the accumulative biogas production also increased with increasing the homogenization pressure and homogenization cycle number. The optimal homogenization pressure was 50 MPa for one homogenization cycle and 40 MPa for two homogenization cycles. The SCOD of the sludge supernatant significantly increased with increasing the homogenization pressure and homogenization cycle number due to the sludge disintegration. The relationship between the biogas production and the sludge disintegration showed that the accumulative biogas and methane production were mainly enhanced by the sludge disintegration, which accelerated the anaerobic digestion process and improved the methane content in the biogas.

  • sewage sludge disintegration by high pressure homogenization a sludge disintegration model
    Journal of Environmental Sciences-china, 2012
    Co-Authors: Yuxua Zhang, Panyue Zhang, Sheng Zhang
    Abstract:

    High-pressure homogenization (HPH) technology was applied as a pretreatment to disintegrate sewage sludge. The effects of homogenization pressure, homogenization cycle number, and total solid content on sludge disintegration were investigated. The sludge disintegration degree (DDCOD), protein concentration, and polysaccharide concentration increased with the increase of homogenization pressure and homogenization cycle number, and decreased with the increase of sludge total solid (TS) content. The maximum DDCOD of 43.94% was achieved at 80 MPa with four homogenization cycles for a 9.58 g/L TS sludge sample. A HPH sludge disintegration model of DDCOD= kNaPb was established by multivariable linear regression to quantify the effects of homogenization parameters. The homogenization cycle exponent a and homogenization pressure exponent b were 0.4763 and 0.7324 respectively, showing that the effect of homogenization pressure (P) was more significant than that of homogenization cycle number (N). The value of the rate constant k decreased with the increase of sludge total solid content. The specific energy consumption increased with the increment of sludge disintegration efficiency. Lower specific energy consumption was required for higher total solid content sludge.