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Isolectric precipitation of sunflower protein was carried out in a 20 m long, 6 mm internal diameter glass tubular pre- cipitator. Effects of feed flow rate, protein concentration in the feed stream, and mean residence time on par...
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Isolectric precipitation of sunflower protein was carried out in a 20 m long, 6 mm internal diameter glass tubular pre- cipitator. Effects of feed flow rate, protein concentration in the feed stream, and mean residence time on particles size dis- tribution(PSD)were studied. The population balance equation(PBE)for the tubular precipitator was solved using the orthogonal colllocation multiple shooting method. A simulated annealing method was used to determine the precipitation kinetic parameters for the nucleation rate, growth rate, aggregation rate, and breakage rate from the experimental data.
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Eastern Iberian Peninsula is characterized by the large occurrence of convective precipitation events, which entail important economic and social damage consequences. In order to prevent and minimize its effects, a good knowledge ...
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Eastern Iberian Peninsula is characterized by the large occurrence of convective precipitation events, which entail important economic and social damage consequences. In order to prevent and minimize its effects, a good knowledge and understanding of the meteorological processes involved are necessary to be achieved. In this regard, an algorithm for classifying convective and stratiform precipitation components has been applied to a decadal precipitation record. Dataset were provided by National Spanish Meteorological Agency (AEMET) for the period 1998-2008. Hourly precipitation records have been analyzed. The goals of this study have been: a) to classify total precipitation into its stratiform and convective components in Levante region (located in the Eastern Spanish Coast) and b) to analyze annual and seasonal trends of such components. For determining both convective and stratiform precipitation components, a suitable exponential function has been used. After a computation process, critical precipitation intensity (so-called Rc) is obtained for each year and season of the studied period. Every precipitation episode in Levante region is classified into prevailing convective or stratiform regime according to the threshold value defined by Rc. The results obtained have been compared to Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA-COARE) to verify the validity of the algorithm. First results show an annual and seasonal significant positive trend in total precipitation and stratiform component for 1998-2008 decade. Further analysis reveals that convective precipitation exhibits no significant trend. Preliminary conclusions state that the total precipitation amount in Levante Region strongly depends on the stratiform component evolution.
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Northwest China is one of the most arid areas in East Asia. Previous studies pointed out that some regions of Northwest China experienced a dry to wet climate change in the past half century. This study analyzed the observed daily...
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Northwest China is one of the most arid areas in East Asia. Previous studies pointed out that some regions of Northwest China experienced a dry to wet climate change in the past half century. This study analyzed the observed daily precipitation during 1961-2000 in Northwest China. Results show that the annual precipitation in Northwest China has different trends in the western region and the eastern region. The western region has a significant increasing trend as shown in previous studies, while the eastern region has a decreasing trend. It is found that the increasing trend in the western region is caused by the increase of the heaviest precipitation in summer, while the decreasing trend in the eastern region is caused by the decrease of the heaviest precipitation in autumn. In order to find out the dominating precipitation type in the change of precipitation, a simple parameter is used to distinguish convective precipitation from stratiform precipitation. It is found that the increase of the heaviest precipitation in summer in the western region resulted from the increased frequency of convective precipitation, and the decrease of the heaviest precipitation in autumn in the eastern region was caused by the decreased frequency of stratiform precipitation. (C) 2015 Elsevier B.V. All rights reserved.
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Quantification of precipitation hardening is a challenging subject as it demands combined knowledge of precipitation strengthening mechanism and precipitate growth/coarsening kinetics. Having not seen many attempts on developing n...
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Quantification of precipitation hardening is a challenging subject as it demands combined knowledge of precipitation strengthening mechanism and precipitate growth/coarsening kinetics. Having not seen many attempts on developing new theories in recent years, the authors are aware of the fact that many existing concepts and developed theories are Sometimes even neglected or misused. This article therefore aims to describe overview on some aspects which have not been fully addressed and/or misused. Recent developments in this subject include an accurate determination of the equilibrium precipitate fraction and interparticle spacing. The influence from precipitation fraction on precipitate coarsening and hardening kinetics was accounted for quantitatively, which allows the hardening quantification to be carried out in a more accurate manner. In addition, difficulties in quantification of precipitation strengthening effects in commercial systems are discussed. Advanced theories on dislocation precipitate interaction mechanisms are required to improve the accuracy in quantification of precipitation hardening to a high level.
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A network of 411 ground stations across Luzon Island, Philippines (12.5-20 degrees N, 119-126.5 degrees E) was used to characterize the diurnal cycles of summer precipitation, in terms of amount (PA), frequency (PF), and intensity...
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A network of 411 ground stations across Luzon Island, Philippines (12.5-20 degrees N, 119-126.5 degrees E) was used to characterize the diurnal cycles of summer precipitation, in terms of amount (PA), frequency (PF), and intensity (PI), during the southwest monsoon season (SWM; May-September) between 2011 and 2018. In addition to monsoon exposure, the effect of topography on the diurnal cycle of precipitation also was investigated by comparing a valley, plain, west- and east-facing coasts near mountains. Results show that monsoon exposure significantly influenced diurnal precipitation such that PA and PF decreased (PI increased) toward the leeward side of Luzon Island. Most topographies showed late afternoon-early evening peaks; however, the east-facing coast exhibited a late night-early morning peak. Orographic effects led to as high PA over mountains and enhanced the spatiotemporal propagation of PA in monsoon-exposed areas. The first (second) half of the diurnal peak exhibited high PI/low PF (low PI/high PF), suggesting both PI and PF are important indicators of PA. Finally, graded analysis revealed that light precipitation (0.01-2.5 mm h(-1)) captured overall precipitation trends across Luzon Island, highlighting the importance of this intensity of precipitation. Heavy precipitation (2.5-7.5 mm h(-1)) peaked in the morning; however, underlying mechanisms remain unknown. The study presents the first examination of the diurnal precipitation cycle in Luzon Island using a dense network of synoptic stations. The study demonstrates the complex effect of topography on precipitation and the importance of the SWM in the diurnal cycle of precipitation.
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The development of supercell storms was simulated using a 2-km-resolution weather research and forecast (WRF) model with spectral (bin) microphysics (WRF-SBM) and a recent version of the Thompson bulk-parameterization scheme. The ...
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The development of supercell storms was simulated using a 2-km-resolution weather research and forecast (WRF) model with spectral (bin) microphysics (WRF-SBM) and a recent version of the Thompson bulk-parameterization scheme. The simulations were performed in clean, semipolluted, and dirty air under two values of relative humidity, conditionally referred to as low and high humidity. Both SBM and the Thompson scheme simulated the development of supercell storm with storm splitting. Both SBM and the Thompson scheme demonstrated that an increase in relative humidity by 10% invigorates convection and increases precipitation by factor of 2, i.e., to much larger extent than can be achieved by variations of the aerosol concentration. At the same time the storms simulated by the schemes are quite different. The maximum updrafts in the Thompson scheme are about 65 m/s, and the left-moving storm prevails. The SBM predicts 35 m/s maximum updrafts, and the right-moving storm prevails in the SBM simulations. While the bulk scheme predicts decrease in precipitation in clean air at both low and high humidity, the SBM indicates decrease precipitation in polluted air under low humidity and increase in precipitation under high humidity. The SBM scheme shows a substantial effect of aerosols on spatial distribution of precipitation, especially in the low-humidity case. The sensitivity of the Thompson scheme to aerosols turns out to be much less than that of SBM. The difference in the results (vertical velocities, microphysical cloud structure, and precipitation) obtained by different schemes is much larger than the changes caused by variation of the aerosol concentration within each scheme. However, the average amount of precipitation in the Thompson scheme in each simulation was about twice that of the corresponding SBM simulation. The possible reasons for such difference are discussed. A scheme for classifying aerosol effects on precipitation from clouds and cloud systems is also discussed.
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Water is a basic element of the natural environment and the most important component in human water management. Rainfall is the main source of water. Therefore, determining the amount of precipitation reaching the ground using sen...
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Water is a basic element of the natural environment and the most important component in human water management. Rainfall is the main source of water. Therefore, determining the amount of precipitation reaching the ground using sensors is crucial information. Precise precipitation data are necessary for better modeling quality, as the observation data from weather stations are used as basics for weather model assessment. The authors compared precipitation from the Hellmann rain gauge (climatic precipitation, 1.0 m above the ground surface) measured throughout the year and the GGI 3000 rain gauge (actual precipitation on the ground level) measured from April to October. Measurement sequences from the years 2011-2020 were considered. The data for analysis were obtained from a weather station located in northern Poland. The authors analyzed the relationships between data from the two sensors. A comparative study showed that the measurements of actual precipitation are higher and there are strong relationships between actual and climatic rainfall (r = 0.99). Using the introduced coefficient it is possible to determine the full-year actual precipitation with high probability, taking into account the precipitation with a correction from the winter half-year and the actual precipitation from the summer half-year, which is of great importance in the calculation of the water balance.
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A gridded data set of daily precipitation records together with percentile-based precipitation indices was utilized to analyze changes in spatiotemporal pattern of precipitation across China in the last 33 years (1980-2012). Ident...
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A gridded data set of daily precipitation records together with percentile-based precipitation indices was utilized to analyze changes in spatiotemporal pattern of precipitation across China in the last 33 years (1980-2012). Identifiable changes in precipitation structure and distinctive spatial variations in precipitation trends were detected at both annual and seasonal timescales. Generally, a slight but discernable increasing trend was observed in annual precipitation, and precipitation increased during summer and winter but decreased in spring and autumn. In addition, great differences were distinguished in the aspects of precipitation day, precipitation amount and precipitation duration among light, moderate and heavy precipitation. Additional analyses of extreme events including wet day, very wet day, daily maximum precipitation, short dry period and long dry period, were also performed, which indicated an upward trend in days with more precipitation. Study of contributions to the precipitation day and amount showed that light and moderate precipitation contributed greatly to the precipitation day while moderate and heavy precipitation contributed greatly to the precipitation amount. Finally, it could be concluded that it was getting drier in southeast China but wetter in southwest China, with severe droughts in northwest China being relieved during the last 33 years.
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Abstract We introduce a technique for identifying daily precipitation records based on the analysis of maximum daily precipitation events within running 30‐day periods. The technique is applied to the E‐OBS daily precipitation d...
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Abstract We introduce a technique for identifying daily precipitation records based on the analysis of maximum daily precipitation events within running 30‐day periods. The technique is applied to the E‐OBS daily precipitation dataset for the European region spanning the period 1950–2018. We find that, on a Europe wide scale, the number of actual precipitation records as defined above exceeds the theoretical value expected under stationary climate conditions by a factor increasing with time by up to 1.6–1.8. This result, which has substantial subregional variability, is indicative of an increase of daily precipitation extremes consistent with what expected from climate warming conditions. We also apply the technique to the ERA5 reanalysis and four illustrative 21st century projections conducted with two regional climate models under the high end RCP8.5 and low end RCP2.6 greenhouse gas concentration pathways. We find a sustained increase of precipitation records throughout the 21st century with respect to the expected values for the RCP8.5 scenario, and a much reduced signal for the RCP2.6. In both cases the overall increase in actual to expected ratios of precipitation records is consistent with the warming trends found in the two scenarios, although this signal is highly variable in space and depends on the model being analysed. Our technique can be useful in studies of detection and attribution of extreme precipitation events and in the assessment of the impacts of increasing extremes under global warming conditions.
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In this study, the effect of deformation-induced-ferrite-transformation (DIFT) rolling on precipitation in Ti-Mo ferrite matrix micro-alloyed steel was investigated by comparing to rolling in austenite non-recrystallisation region...
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In this study, the effect of deformation-induced-ferrite-transformation (DIFT) rolling on precipitation in Ti-Mo ferrite matrix micro-alloyed steel was investigated by comparing to rolling in austenite non-recrystallisation region. The precipitate volume fraction and precipitation-starting time-temperature (PTT) curves under two kinds of process were calculated by thermodynamic and kinetic calculation, and the effects of non-recrystallisation rolling and DIFT rolling on the contribution of strengthening mechanisms were quantitatively analysed. The results showed that comparing with rolling in the austenite non-recrystallisation region, carbides in the steel by DIFT rolling were finer and more uniform. Moreover, DIFT rolling could enhance fine grain strengthening and precipitation strengthening simultaneously, and the increments of fine grain and precipitation strengthening were 34 and 63.7MPa, respectively.
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