Soil modulates the effect of precipitation seasonality on bioenergy crop production

USDA-ARS?s Scientific Manuscript database

Background/Questions/Methods Future climate change scenarios remain uncertain with respect to precipitation amounts and variability. In the U.S. Great Plains, spring precipitation is expected to decrease in the lower Great Plains but increase 20%–40% in the upper Mississippi Valley, suggesting pot...

Development of a Video-Microscopic Tool To Evaluate the Precipitation Kinetics of Poorly Water Soluble Drugs: A Case Study with Tadalafil and HPMC.

PubMed

Christfort, Juliane Fjelrad; Plum, Jakob; Madsen, Cecilie Maria; Nielsen, Line Hagner; Sandau, Martin; Andersen, Klaus; Müllertz, Anette; Rades, Thomas

2017-12-04

Many drug candidates today have a low aqueous solubility and, hence, may show a low oral bioavailability, presenting a major formulation and drug delivery challenge. One way to increase the bioavailability of these drugs is to use a supersaturating drug delivery strategy. The aim of this study was to develop a video-microscopic method, to evaluate the effect of a precipitation inhibitor on supersaturated solutions of the poorly soluble drug tadalafil, using a novel video-microscopic small scale setup. Based on preliminary studies, a degree of supersaturation of 29 was chosen for the supersaturation studies with tadalafil in FaSSIF. Different amounts of hydroxypropyl methyl cellulose (HPMC) were predissolved in FaSSIF to give four different concentrations, and the supersaturated system was then created using a solvent shift method. Precipitation of tadalafil from the supersaturated solutions was monitored by video-microscopy as a function of time. Single-particle analysis was possible using commercially available software; however, to investigate the entire population of precipitating particles (i.e., their number and area covered in the field of view), an image analysis algorithm was developed (multiparticle analysis). The induction time for precipitation of tadalafil in FaSSIF was significantly prolonged by adding 0.01% (w/v) HPMC to FaSSIF, and the maximum inhibition was reached at 0.1% (w/v) HPMC, after which additional HPMC did not further increase the induction time. The single-particle and multiparticle analyses yielded the same ranking of the HPMC concentrations, regarding the inhibitory effect on precipitation. The developed small scale method to assess the effect of precipitation inhibitors can speed up the process of choosing the right precipitation inhibitor and the concentration to be used.

The influence of non-ionisable excipients on precipitation parameters measured using the CheqSol method.

PubMed

Etherson, Kelly; Halbert, Gavin; Elliott, Moira

2016-09-01

The aim of this study was to determine the influence of non-ionisable excipients hydroxypropyl-β-cyclodextrin (HPβCD) and poloxamers 407 and 188 on the supersaturation and precipitation kinetics of ibuprofen, gliclazide, propranolol and atenolol induced through solution pH shifts using the CheqSol method. The drug's kinetic and intrinsic aqueous solubilities were measured in the presence of increasing excipient concentrations using the CheqSol method. Experimental data rate of change of pH with time was also examined to determine excipient-induced parachute effects and influence on precipitation rates. The measured kinetic and intrinsic solubilities provide a determination of the influence of each excipient on supersaturation index, and the area under the CheqSol curve can measure the parachute capability of excipients. The excipients influence on precipitation kinetics can be measured with novel parameters; for example, the precipitation pH or percentage ionised drug at the precipitation point, which provide further information on the excipient-induced changes in precipitation performance. This method can therefore be employed to measure the influence of non-ionisable excipients on the kinetic solubility behaviour of supersaturated solutions of ionisable drugs and to provide data, which discriminates between excipient systems during precipitation. © 2016 Royal Pharmaceutical Society.

Effects of latent heat in various cloud microphysics processes on autumn rainstorms with different intensities on Hainan Island, China

NASA Astrophysics Data System (ADS)

Li, Jiangnan; Wu, Kailu; Li, Fangzhou; Chen, Youlong; Huang, Yanbin; Feng, YeRong

2017-06-01

In this study, we used the Weather Research and Forecasting (WRF) and WRF-3DVAR models to perform a series of simulations of two autumn rainstorms on Hainan Island. The results of neighborhood fractions and Hanssen skill scoring (FSS, HSS) methods show that the control experiments reproduced well two heavy rainfall episodes. Effects of latent heat in various cloud microphysical processes are different at distinct intensities or stages of precipitation. In the absence of any heating effect of deposition, precipitation weakened. The greater was the precipitation, the more significant was the weakening effect. Ascending movement at upper troposphere could be weakened or descending movement at lower troposphere enhanced. With decreases in the strength of precipitation, cloud ice, snow, graupel, and rainwater, increases in latent heat lessened. With weak precipitation, at upper troposphere the rainwater content increased and snow and ice content decreased, whereas at middle troposphere, the ice, snow, and graupel contents increased. Latent heating increased at middle and lower troposphere and decreased at upper troposphere. The absence of any heating effect of freezing had little effect on precipitation. By removing the evaporative cooling of cloud water, the interactions between vertical movement and cloud microphysical processes resulted in a weakening of strong precipitation and an intensification of weak precipitation. However, in the preliminary stages of these two precipitation events, snow, graupel, cloud ice, and rainwater all increased, and precipitation was enhanced in both. In the later stages, strong precipitation systems weakened and weak precipitation systems strengthened. Latent heating first increased and then dropped in strong precipitation systems, whereas they continuously increased in weak precipitation systems.

Precipitation-Frequency and Discharge-Frequency Relations for Basins Less than 32 Square Miles in Kansas

USGS Publications Warehouse

Perry, Charles A.

2008-01-01

Precipitation-frequency and discharge-frequency relations for small drainage basins with areas less than 32 square miles in Kansas were evaluated to reduce the uncertainty of discharge-frequency estimates. Gaged-discharge records were used to develop discharge-frequency equations for the ratio of discharge to drainage area (Q/A) values using data from basins with variable soil permeability, channel slope, and mean annual precipitation. Soil permeability and mean annual precipitation are the dominant basin characteristics in the multiple linear regression analyses. In addition, 28 discharge measurements at ungaged sites by indirect surveying methods and by velocity meters also were used in this analysis to relate precipitation-recurrence interval to discharge-recurrence interval. Precipitation-recurrence interval for each of these discharge measurements were estimated from weather-radar estimates of precipitation and from nearby raingages. Time of concentration for each basin for each of the ungaged sites was computed and used to determine the precipitation-recurrence interval based on precipitation depth and duration. The ratio of discharge/drainage area (Q/A) value for each event was then assigned to that precipitation-recurrence interval. The relation between the ratio of discharge/drainage area (Q/A) and precipitation-recurrence interval for all 28 measured events resulted in a correlation coefficient of 0.79. Using basins less than 5.4 mi2 only, the correlation decreases to 0.74. However, when basins greater than 5.4 and less than 32 mi2 are examined the relation improves to a correlation coefficient of 0.95. There were a sufficient number of discharge and radar-measured precipitation events for both the 5-year (8 events) and the 100-year (11 events) recurrence intervals to examine the effect of basin characteristics on the Q/A values for basins less than 32 mi2. At the 5-year precipitation-/discharge-recurrence interval, channel slope was a significant predictor (r=0.99) of Q/A. Permeability (r=0.68) also had a significant effect on Q/A values for the 5-year recurrence interval. At the 100-year recurrence interval, permeability, channel slope, and mean annual precipitation did not have a significant effect on Q/A; however, time of concentration was a significant factor in determining Q/A for the 100-year events with greater times of concentration resulting in lower Q/A values. Additional high-recurrence interval (5-, 10-, 25-, 50-, and 100-year) precipitation/discharge data are needed to confirm these relations suggested above. Discharge data with attendant basin-wide precipitation data from precipitation-radar estimates provides a unique opportunity to study the effects of basin characteristics on the relation between precipitation recurrence interval and discharge-recurrence interval. Discharge-frequency values from the Q/A equations, the rational method, and the Kansas discharge-frequency equations (KFFE) were compared to 28 measured weather-radar precipitation-/discharge-frequency values. The association between precipitation frequency from weather-radar estimates and the frequency of the resulting discharge was shown in these comparisons. The measured and Q/A equation computed discharges displayed the best equality from low to high discharges of the three methods. Here the slope of the line was nearly 1:1 (y=0.9844x0.9677). Comparisons with the rational method produced a slope greater than 1:1 (y=0.0722x1.235), and the KFFE equations produced a slope less than 1:1 (y=5.9103x0.7475). The Q/A equation standard error of prediction averaged 0.1346 log units for the 5.4-to 32-square-mile group and 0.0944 log units for the less than 5.4-square mile group. The KFFE standard error averaged 0.2107 log units for the less-than-30-square-mile equations. Using the Q/A equations for determining discharge frequency values for ungaged sites thus appears to be a good alternative to the other two methods because of this s

Characterization of the evolution of the volume fraction of precipitates in aged AlMgSiCu alloys using DSC technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esmaeili, Shahrzad; Lloyd, David J.

2005-11-15

Differential scanning calorimetry is used to quantify the evolution of the volume fraction of precipitates during age hardening in AlMgSiCu alloys. The calorimetry tests are run on alloy samples after aging for various times at 180 deg. C and the change in the collective heat effects from the major precipitation and dissolution processes in each run are used to determine the precipitation state of the samples. The method is implemented on alloys with various thermal histories prior to artificial aging, including commercial pre-aging histories. The estimated values for the relative volume fraction of precipitates are compared with the results frommore » a newly developed analytical method using isothermal calorimetry and a related quantitative transmission electron microscopy work. Excellent agreement is obtained between the results from various methods.« less

SEPARATING PROTOACTINIUM WITH MANGANESE DIOXIDE

DOEpatents

Seaborg, G.T.; Gofman, J.W.; Stoughton, R.W.

1958-04-22

The preparation of U/sup 235/ and an improved method for isolating Pa/ sup 233/ from foreign products present in neutronirradiated thorium is described. The method comprises forming a solution of neutron-irradiated thorium together with a manganous salt, then adding potassium permanganate to precipitate the manganese as manganese dioxide whereby protoactinium is carried down with the nnanganese dioxide dissolving the precipitate, adding a soluble zirconium salt, and adding phosphate ion to precipitate zirconium phosphate whereby protoactinium is then carried down with the zirconium phosphate to effect a further concentration.

Photocatalytic degradation of methylene blue dye by zinc oxide nanoparticles obtained from precipitation and sol-gel methods.

PubMed

Balcha, Abebe; Yadav, Om Prakash; Dey, Tania

2016-12-01

Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10 -3 and 12.4 × 10 -3  min -1 , respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

A simple and effective method for detecting precipitated proteins in MALDI-TOF MS.

PubMed

Oshikane, Hiroyuki; Watabe, Masahiko; Nakaki, Toshio

2018-04-01

MALDI-TOF MS has developed rapidly into an essential analytical tool for the life sciences. Cinnamic acid derivatives are generally employed in routine molecular weight determinations of intact proteins using MALDI-TOF MS. However, a protein of interest may precipitate when mixed with matrix solution, perhaps preventing MS detection. We herein provide a simple approach to enable the MS detection of such precipitated protein species by means of a "direct deposition method" -- loading the precipitant directly onto the sample plate. It is thus expected to improve routine MS analysis of intact proteins. Copyright © 2018. Published by Elsevier Inc.

A Statistical Method for Reducing Sidelobe Clutter for the Ku-Band Precipitation Radar on Board the GPM Core Observatory

NASA Technical Reports Server (NTRS)

Kubota, Takuji; Iguchi, Toshio; Kojima, Masahiro; Liao, Liang; Masaki, Takeshi; Hanado, Hiroshi; Meneghini, Robert; Oki, Riko

2016-01-01

A statistical method to reduce the sidelobe clutter of the Ku-band precipitation radar (KuPR) of the Dual-Frequency Precipitation Radar (DPR) on board the Global Precipitation Measurement (GPM) Core Observatory is described and evaluated using DPR observations. The KuPR sidelobe clutter was much more severe than that of the Precipitation Radar on board the Tropical Rainfall Measuring Mission (TRMM), and it has caused the misidentification of precipitation. The statistical method to reduce sidelobe clutter was constructed by subtracting the estimated sidelobe power, based upon a multiple regression model with explanatory variables of the normalized radar cross section (NRCS) of surface, from the received power of the echo. The saturation of the NRCS at near-nadir angles, resulting from strong surface scattering, was considered in the calculation of the regression coefficients.The method was implemented in the KuPR algorithm and applied to KuPR-observed data. It was found that the received power from sidelobe clutter over the ocean was largely reduced by using the developed method, although some of the received power from the sidelobe clutter still remained. From the statistical results of the evaluations, it was shown that the number of KuPR precipitation events in the clutter region, after the method was applied, was comparable to that in the clutter-free region. This confirms the reasonable performance of the method in removing sidelobe clutter. For further improving the effectiveness of the method, it is necessary to improve the consideration of the NRCS saturation, which will be explored in future work.

Extraction of rare earth elements from low-grade Bauxite via precipitation reaction

NASA Astrophysics Data System (ADS)

Kusrini, E.; Nurani, Y.; Bahari, ZJ

2018-03-01

The aim of this research was to determine the optimum hydrometallurgical parameters to extract the rare earth elements (REE) from low-grade bauxite through acid leaching and precipitation reaction. REE or lanthanide recovery by a precipitation method with sodium sulphate and sodium phosphate as precipitation agents is reported where the effect of pH and recovery of REE are described. The metal composition of REE in low-grade bauxite after treatment were analyzed by ICP-OES. The total recovery values of REE elements at the first precipitation reaction using sodium sulphate as the precipitation agent at pH 3.5 showed ~68.2% of lanthanum, ~18.9% cerium, and ~7.8% yttrium. Lanthanum was the rare-earth element present at the highest concentration in the low-grade bauxite after the series treatments. An optimum pH of 3.5 for precipitation of rare-earth elements using sodium sulphate was demonstrated where this method is recommended for the extraction of REE elements from low-grade bauxite.

Effect of the precipitation interpolation method on the performance of a snowmelt runoff model

NASA Astrophysics Data System (ADS)

Jacquin, Alexandra

2014-05-01

Uncertainties on the spatial distribution of precipitation seriously affect the reliability of the discharge estimates produced by watershed models. Although there is abundant research evaluating the goodness of fit of precipitation estimates obtained with different gauge interpolation methods, few studies have focused on the influence of the interpolation strategy on the response of watershed models. The relevance of this choice may be even greater in the case of mountain catchments, because of the influence of orography on precipitation. This study evaluates the effect of the precipitation interpolation method on the performance of conceptual type snowmelt runoff models. The HBV Light model version 4.0.0.2, operating at daily time steps, is used as a case study. The model is applied in Aconcagua at Chacabuquito catchment, located in the Andes Mountains of Central Chile. The catchment's area is 2110[Km2] and elevation ranges from 950[m.a.s.l.] to 5930[m.a.s.l.] The local meteorological network is sparse, with all precipitation gauges located below 3000[m.a.s.l.] Precipitation amounts corresponding to different elevation zones are estimated through areal averaging of precipitation fields interpolated from gauge data. Interpolation methods applied include kriging with external drift (KED), optimal interpolation method (OIM), Thiessen polygons (TP), multiquadratic functions fitting (MFF) and inverse distance weighting (IDW). Both KED and OIM are able to account for the existence of a spatial trend in the expectation of precipitation. By contrast, TP, MFF and IDW, traditional methods widely used in engineering hydrology, cannot explicitly incorporate this information. Preliminary analysis confirmed that these methods notably underestimate precipitation in the study catchment, while KED and OIM are able to reduce the bias; this analysis also revealed that OIM provides more reliable estimations than KED in this region. Using input precipitation obtained by each method, HBV parameters are calibrated with respect to Nash-Sutcliffe efficiency. The performance of HBV in the study catchment is not satisfactory. Although volumetric errors are modest, efficiency values are lower than 70%. Discharge estimates resulting from the application of TP, MFF and IDW obtain similar model efficiencies and volumetric errors. These error statistics moderately improve if KED or OIM are used instead. Even though the quality of precipitation estimates of distinct interpolation methods is dissimilar, the results of this study show that these differences do not necessarily produce noticeable changes in HBV's model performance statistics. This situation arises because the calibration of the model parameters allows some degree of compensation of deficient areal precipitation estimates, mainly through the adjustment of model simulated evaporation and glacier melt, as revealed by the analysis of water balances. In general, even if there is a good agreement between model estimated and observed discharge, this information is not sufficient to assert that the internal hydrological processes of the catchment are properly simulated by a watershed model. Other calibration criteria should be incorporated if a more reliable representation of these processes is desired. Acknowledgements: This research was funded by FONDECYT, Research Project 1110279. The HBV Light software used in this study was kindly provided by J. Seibert, Department of Geography, University of Zürich.

Assessing the applicability of WRF optimal parameters under the different precipitation simulations in the Greater Beijing Area

NASA Astrophysics Data System (ADS)

Di, Zhenhua; Duan, Qingyun; Wang, Chen; Ye, Aizhong; Miao, Chiyuan; Gong, Wei

2018-03-01

Forecasting skills of the complex weather and climate models have been improved by tuning the sensitive parameters that exert the greatest impact on simulated results based on more effective optimization methods. However, whether the optimal parameter values are still work when the model simulation conditions vary, which is a scientific problem deserving of study. In this study, a highly-effective optimization method, adaptive surrogate model-based optimization (ASMO), was firstly used to tune nine sensitive parameters from four physical parameterization schemes of the Weather Research and Forecasting (WRF) model to obtain better summer precipitation forecasting over the Greater Beijing Area in China. Then, to assess the applicability of the optimal parameter values, simulation results from the WRF model with default and optimal parameter values were compared across precipitation events, boundary conditions, spatial scales, and physical processes in the Greater Beijing Area. The summer precipitation events from 6 years were used to calibrate and evaluate the optimal parameter values of WRF model. Three boundary data and two spatial resolutions were adopted to evaluate the superiority of the calibrated optimal parameters to default parameters under the WRF simulations with different boundary conditions and spatial resolutions, respectively. Physical interpretations of the optimal parameters indicating how to improve precipitation simulation results were also examined. All the results showed that the optimal parameters obtained by ASMO are superior to the default parameters for WRF simulations for predicting summer precipitation in the Greater Beijing Area because the optimal parameters are not constrained by specific precipitation events, boundary conditions, and spatial resolutions. The optimal values of the nine parameters were determined from 127 parameter samples using the ASMO method, which showed that the ASMO method is very highly-efficient for optimizing WRF model parameters.

SULFIDE METHOD PLUTONIUM SEPARATION

DOEpatents

Duffield, R.B.

1958-08-12

A process is described for the recovery of plutonium from neutron irradiated uranium solutions. Such a solution is first treated with a soluble sullide, causing precipitation of the plutoniunn and uraniunn values present, along with those impurities which form insoluble sulfides. The precipitate is then treated with a solution of carbonate ions, which will dissolve the uranium and plutonium present while the fission product sulfides remain unaffected. After separation from the residue, this solution may then be treated by any of the usual methods, such as formation of a lanthanum fluoride precipitate, to effect separation of plutoniunn from uranium.

A study on large-scale nudging effects in regional climate model simulation

NASA Astrophysics Data System (ADS)

Yhang, Yoo-Bin; Hong, Song-You

2011-05-01

The large-scale nudging effects on the East Asian summer monsoon (EASM) are examined using the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM). The NCEP/DOE reanalysis data is used to provide large-scale forcings for RSM simulations, configured with an approximately 50-km grid over East Asia, centered on the Korean peninsula. The RSM with a variant of spectral nudging, that is, the scale selective bias correction (SSBC), is forced by perfect boundary conditions during the summers (June-July-August) from 1979 to 2004. The two summers of 2000 and 2004 are investigated to demonstrate the impact of SSBC on precipitation in detail. It is found that the effect of SSBC on the simulated seasonal precipitation is in general neutral without a discernible advantage. Although errors in large-scale circulation for both 2000 and 2004 are reduced by using the SSBC method, the impact on simulated precipitation is found to be negative in 2000 and positive in 2004 summers. One possible reason for a different effect is that precipitation in the summer of 2004 is characterized by a strong baroclinicity, while precipitation in 2000 is caused by thermodynamic instability. The reduction of convective rainfall over the oceans by the application of the SSBC method seems to play an important role in modeled atmosphere.

Micro and colloidal stickie pacification with precipitated calcium carbonate

Treesearch

John H. Klungness; Roland L. Gleisner; Marguerite S. Sykes

2002-01-01

Colloidal stickies that build up in mill process water during pulping are problematic and difficult to remove. We examined precipitated calcium carbonate (PCC) as a means to ameliorate process water stickies. The effectiveness of PCC added directly into a slurry of deinked pulp was compared with in situ precipitation of PCC by the fiber loading method. We found that...

Correction of Excessive Precipitation over Steep and High Mountains in a GCM: A Simple Method of Parameterizing the Thermal Effects of Subgrid Topographic Variation

NASA Technical Reports Server (NTRS)

Chao, Winston C.

2015-01-01

The excessive precipitation over steep and high mountains (EPSM) in GCMs and meso-scale models is due to a lack of parameterization of the thermal effects of the subgrid-scale topographic variation. These thermal effects drive subgrid-scale heated slope induced vertical circulations (SHVC). SHVC provide a ventilation effect of removing heat from the boundary layer of resolvable-scale mountain slopes and depositing it higher up. The lack of SHVC parameterization is the cause of EPSM. The author has previously proposed a method of parameterizing SHVC, here termed SHVC.1. Although this has been successful in avoiding EPSM, the drawback of SHVC.1 is that it suppresses convective type precipitation in the regions where it is applied. In this article we propose a new method of parameterizing SHVC, here termed SHVC.2. In SHVC.2 the potential temperature and mixing ratio of the boundary layer are changed when used as input to the cumulus parameterization scheme over mountainous regions. This allows the cumulus parameterization to assume the additional function of SHVC parameterization. SHVC.2 has been tested in NASA Goddard's GEOS-5 GCM. It achieves the primary goal of avoiding EPSM while also avoiding the suppression of convective-type precipitation in regions where it is applied.

METHOD FOR REMOVING CONTAMINATION FROM PRECIPITATES

DOEpatents

Stahl, G.W.

1959-01-01

An improvement in the bismuth phosphate carrier precipitation process is presented for the recovery and purification of plutonium. When plutonium, in the tetravalent state, is carried on a bismuth phosphate precipitate, amounts of centain of the fission products are carried along with the plutonium. The improvement consists in washing such fission product contaminated preeipitates with an aqueous solution of ammonium hydrogen fluoride. since this solution has been found to be uniquely effective in washing fission production contamination from the bismuth phosphate precipitate.

Topographical effects on the distributions of rainfall and 18O distributions: a case in Miyake Island, Japan

NASA Astrophysics Data System (ADS)

Tang, Changyuan; Shindo, Shizuo; Machida, Isao

1998-03-01

In this paper, we try to calculate precipitation in Miyake Island, Japan. In order to know the temporal and spatial variations of precipitation, we have set 15 rain gauges randomly in the island to collect the monthly precipitation data since June 1994. It is found that the precipitation is very different from point to point. First, we used statistical methods to get the correlations between the monthly precipitation at our survey points and that at the weather station. Next, regression analyses were used to establish formulae to calculate precipitation as a function of altitude, aspect of the geomorphological surface and wind direction. Based on these results, distributions of monthly and yearly precipitation and 18O over the island were assessed. The results show that landscape patterns strongly influence precipitation distribution over the island, with the highest precipitation being found on the windward side, about 400-600 m above sea level. Even at places at the same altitude, the precipitation was different because of the aspect of the landscape. At the same time, altitude effects for 18O on both the windward and leeward sides were -0·10/100 m and -0·15/100 m, respectively. Comparing with the distribution of precipitation distribution, it was also found that 18O for the windward and leeward sides was different from that for precipitation, which means that both topographical effects must be considered separately.

Effect of synthesizing method on the properties of LiFePO4/C composite for rechargeable lithium-ion batteries

NASA Astrophysics Data System (ADS)

Yoon, Man-Soon; Islam, Mobinul; Park, Young Min; Ur, Soon-Chul

2013-03-01

Olivine-type LiFePO4/C cathode materials are fabricated with FePO4 powders that are pre-synthesized by two different processes from iron chloride solution. Process I is a modified precipitation method which is implemented by the pH control of a solution using NH4OH to form FePO4 precipitates at room temperature. Process II is a conventional precipitation method, of which H3PO4 (85%) solution is gradually added to a FeCl3 solution during the process to maintain a designated mole ratio. The solution is subsequently aged at 90°C in a water bath until FePO4 precipitates appear. In order to synthesize LiFePO4/C composites, each batch of FePO4 powders is then mixed with pre-milled lithium carbonate and glucose (8 wt. %) as a carbon source in a ball-mill. The structural characteristics of both LiFePO4/C composites fabricated using iron phospates from two different routes have been examined employing XRD and SEM. The modified precipitation process is considered to be a relatively simple and effective process for the preparation of LiFePO4/C composites owing to their excellent electrochemical properties and rate capabilities.

Quantification of the impact of precipitation spatial distribution uncertainty on predictive uncertainty of a snowmelt runoff model

NASA Astrophysics Data System (ADS)

Jacquin, A. P.

2012-04-01

This study is intended to quantify the impact of uncertainty about precipitation spatial distribution on predictive uncertainty of a snowmelt runoff model. This problem is especially relevant in mountain catchments with a sparse precipitation observation network and relative short precipitation records. The model analysed is a conceptual watershed model operating at a monthly time step. The model divides the catchment into five elevation zones, where the fifth zone corresponds to the catchment's glaciers. Precipitation amounts at each elevation zone i are estimated as the product between observed precipitation at a station and a precipitation factor FPi. If other precipitation data are not available, these precipitation factors must be adjusted during the calibration process and are thus seen as parameters of the model. In the case of the fifth zone, glaciers are seen as an inexhaustible source of water that melts when the snow cover is depleted.The catchment case study is Aconcagua River at Chacabuquito, located in the Andean region of Central Chile. The model's predictive uncertainty is measured in terms of the output variance of the mean squared error of the Box-Cox transformed discharge, the relative volumetric error, and the weighted average of snow water equivalent in the elevation zones at the end of the simulation period. Sobol's variance decomposition (SVD) method is used for assessing the impact of precipitation spatial distribution, represented by the precipitation factors FPi, on the models' predictive uncertainty. In the SVD method, the first order effect of a parameter (or group of parameters) indicates the fraction of predictive uncertainty that could be reduced if the true value of this parameter (or group) was known. Similarly, the total effect of a parameter (or group) measures the fraction of predictive uncertainty that would remain if the true value of this parameter (or group) was unknown, but all the remaining model parameters could be fixed. In this study, first order and total effects of the group of precipitation factors FP1- FP4, and the precipitation factor FP5, are calculated separately. First order and total effects of the group FP1- FP4 are much higher than first order and total effects of the factor FP5, which are negligible This situation is due to the fact that the actual value taken by FP5 does not have much influence in the contribution of the glacier zone to the catchment's output discharge, mainly limited by incident solar radiation. In addition to this, first order effects indicate that, in average, nearly 25% of predictive uncertainty could be reduced if the true values of the precipitation factors FPi could be known, but no information was available on the appropriate values for the remaining model parameters. Finally, the total effects of the precipitation factors FP1- FP4 are close to 41% in average, implying that even if the appropriate values for the remaining model parameters could be fixed, predictive uncertainty would be still quite high if the spatial distribution of precipitation remains unknown. Acknowledgements: This research was funded by FONDECYT, Research Project 1110279.

Effect of precipitation pattern on leaching of preservative from treated wood and implications for accelerated testing

Treesearch

Stan Lebow

2014-01-01

There is a need to develop improved accelerated test methods for evaluating the leaching of wood preservatives from treated wood exposed to precipitation. In this study the effects of rate of rainfall and length of intervals between rainfall events on leaching was evaluated by exposing specimens to varying patterns of simulated rainfall under controlled laboratory...

A method of evaluating effects of antecedent precipitation on duststorms and its application to Yuma, Arizona, 1981-1988

USGS Publications Warehouse

MacKinnon, D.J.; Elder, D.F.; Helm, P.J.; Tuesink, M.F.; Nist, C.A.

1990-01-01

Precipitation causes several short- and long-term effects on wind-induced surface erodibility and subsequent dust emission. Among the principal effects considered by this paper are soil moisture, soil crusts, and vegetation. A quantitative method is developed to assess these effects using differences between the potential and the actual amounts of dust emitted from dust sources as inferred from surface meteorological measurements obtained downwind from those sources. The results of this assessment must be interpreted with caution, however, when the size and location of dust sources are unknown. Using meteorological data recorded near Yuma, Arizona at the Yuma Marine Corps Air Station (YMCAS), the method is applied to calculate the potential and actual amounts of dust emitted from upwind dust sources during the spring and fall/winter seasons between January 1, 1981 and May 31, 1988. (Spring is considered to be the period between February 1 and May 31; fall/winter, between October 1 and January 31.) Because summer precipitation is intermittent and wind patterns are localized, summer meteorological data are not used to evaluate regional correlations between precipitation and dust storms. For the period between 1981 and 1988, a correlation of -0.60 was found between fall/winter precipitation and the actual amount of dust emitted from sources upwind of YMCAS during the following spring. A particularly strong reduction in dust emission was noted during the springs of 1983 and 1984 following the start of an 'El Nino event' in fall/winter 1982. Photographs taken at a geological and meteorological data-collection (Geomet) site, located in the natural desert 25 km southeast of YMCAS, show a correspondence between increased antecedent precipitation recorded at the site and increased vegetation. Whereas the annual precipitation totals at YMCAS and the Geomet site from the beginning of 1982 through 1984 are high, their seasonal totals, especially during the fall/winter seasons, are disparate. This fall/winter precipitation disparity may account for evidence suggesting that significant vegetation growth occurred at dust sources upwind of YMCAS by spring 1983, but that such growth did not occur at the Geomet site until fall/ winter of 1983. Spatial inhomogeneity in fall/winter precipitation probably contributed to the relatively low correlation (-0.60) between fall/winter precipitation recorded at YMCAS and the actual amount of dust emitted from upwind sources during the following spring. ?? 1990 Kluwer Academic Publishers.

Corrosion behavior of ferritic stainless steel with 15wt% chromium for the automobile exhaust system

NASA Astrophysics Data System (ADS)

Li, Hua-bing; Jiang, Zhou-hua; Feng, Hao; Zhu, Hong-chun; Sun, Bin-han; Li, Zhen

2013-09-01

The effect of chloride ion concentration, pH value, and grain size on the pitting corrosion resistance of a new ferritic stainless steel with 15wt% Cr was investigated using the anodic polarization method. The semiconducting properties of passive films with different chloride ion concentrations were performed using capacitance measurement and Mott-Schottky analysis methods. The aging precipitation and intergranular corrosion behavior were evaluated at 400-900°C. It is found that the pitting potential decreases when the grain size increases. With the increase in chloride ion concentration, the doping density and the flat-bland potential increase but the thickness of the space charge layer decreases. The pitting corrosion resistance increases rapidly with the decrease in pH value. Precipitants is identified as Nb(C,N) and NbC, rather than Cr-carbide. The intergranular corrosion is attributed to the synergistic effects of Nb(C,N) and NbC precipitates and Cr segregation adjacent to the precipitates.

Systematic Assessment of Seven Solvent and Solid-Phase Extraction Methods for Metabolomics Analysis of Human Plasma by LC-MS

NASA Astrophysics Data System (ADS)

Sitnikov, Dmitri G.; Monnin, Cian S.; Vuckovic, Dajana

2016-12-01

The comparison of extraction methods for global metabolomics is usually executed in biofluids only and focuses on metabolite coverage and method repeatability. This limits our detailed understanding of extraction parameters such as recovery and matrix effects and prevents side-by-side comparison of different sample preparation strategies. To address this gap in knowledge, seven solvent-based and solid-phase extraction methods were systematically evaluated using standard analytes spiked into both buffer and human plasma. We compared recovery, coverage, repeatability, matrix effects, selectivity and orthogonality of all methods tested for non-lipid metabolome in combination with reversed-phased and mixed-mode liquid chromatography mass spectrometry analysis (LC-MS). Our results confirmed wide selectivity and excellent precision of solvent precipitations, but revealed their high susceptibility to matrix effects. The use of all seven methods showed high overlap and redundancy which resulted in metabolite coverage increases of 34-80% depending on LC-MS method employed as compared to the best single extraction protocol (methanol/ethanol precipitation) despite 7x increase in MS analysis time and sample consumption. The most orthogonal methods to methanol-based precipitation were ion-exchange solid-phase extraction and liquid-liquid extraction using methyl-tertbutyl ether. Our results help facilitate rational design and selection of sample preparation methods and internal standards for global metabolomics.

Systematic Assessment of Seven Solvent and Solid-Phase Extraction Methods for Metabolomics Analysis of Human Plasma by LC-MS

PubMed Central

Sitnikov, Dmitri G.; Monnin, Cian S.; Vuckovic, Dajana

2016-01-01

The comparison of extraction methods for global metabolomics is usually executed in biofluids only and focuses on metabolite coverage and method repeatability. This limits our detailed understanding of extraction parameters such as recovery and matrix effects and prevents side-by-side comparison of different sample preparation strategies. To address this gap in knowledge, seven solvent-based and solid-phase extraction methods were systematically evaluated using standard analytes spiked into both buffer and human plasma. We compared recovery, coverage, repeatability, matrix effects, selectivity and orthogonality of all methods tested for non-lipid metabolome in combination with reversed-phased and mixed-mode liquid chromatography mass spectrometry analysis (LC-MS). Our results confirmed wide selectivity and excellent precision of solvent precipitations, but revealed their high susceptibility to matrix effects. The use of all seven methods showed high overlap and redundancy which resulted in metabolite coverage increases of 34–80% depending on LC-MS method employed as compared to the best single extraction protocol (methanol/ethanol precipitation) despite 7x increase in MS analysis time and sample consumption. The most orthogonal methods to methanol-based precipitation were ion-exchange solid-phase extraction and liquid-liquid extraction using methyl-tertbutyl ether. Our results help facilitate rational design and selection of sample preparation methods and internal standards for global metabolomics. PMID:28000704

USSR and Eastern Europe Scientific Abstracts, Geophysics, Astronomy and Space, Number 394.

DTIC Science & Technology

1977-04-13

Abstracts of Scientific Articles 10 Temperature and Wind Variations in Upper Atmosphere 10 Prediction of Precipitation for Five Days 10 Short...34 Method in Sea Gravimetry ... 30 Frequency Characteristics of Filter in "Points of Intersection" Method 30 Page Gravitational Anomalies in the...Inclination of Axes of Rotation and Orbits of Planets 47 Effect of Solar Activity on Precipitation Regime 47 Gravitational Orientation Systems with Two

Multiscale Modeling of Inclusions and Precipitation Hardening in Metal Matrix Composites: Application to Advanced High-Strength Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Askari, Hesam; Zbib, Hussein M.; Sun, Xin

In this study, the strengthening effect of inclusions and precipitates in metals is investigated within a multiscale approach that utilizes models at various length scales, namely, Molecular Mechanics (MM), discrete Dislocation Dynamics (DD), and an Eigenstrain Inclusion Method (EIM). Particularly, precipitates are modeled as hardsoft particles whose stress fields interact with dislocations. The stress field resulting from the elastic mismatch between the particles and the matrix is accounted for through the EIM. While the MM method is employed for the purpose of developing rules for DD for short range interaction between a single dislocation and an inclusion, the DD methodmore » is used to predict the strength of the composite resulting from the interaction between ensembles of dislocations and particles. As an application to this method, the mechanical behavior of Advanced High Strength Steel (AHSS) is investigated and the results are then compared to the experimental data. The results show that the finely dispersive precipitates can strengthen the material by pinning the dislocations up to a certain shear stress and retarding the recovery, as well as annihilation of dislocations. The DD results show that strengthening due to nano sized particles is a function of the density and size of the precipitates. This size effect is then explained using a mechanistic model developed based on dislocation-particle interaction.« less

Spatial interpolation schemes of daily precipitation for hydrologic modeling

USGS Publications Warehouse

Hwang, Y.; Clark, M.R.; Rajagopalan, B.; Leavesley, G.

2012-01-01

Distributed hydrologic models typically require spatial estimates of precipitation interpolated from sparsely located observational points to the specific grid points. We compare and contrast the performance of regression-based statistical methods for the spatial estimation of precipitation in two hydrologically different basins and confirmed that widely used regression-based estimation schemes fail to describe the realistic spatial variability of daily precipitation field. The methods assessed are: (1) inverse distance weighted average; (2) multiple linear regression (MLR); (3) climatological MLR; and (4) locally weighted polynomial regression (LWP). In order to improve the performance of the interpolations, the authors propose a two-step regression technique for effective daily precipitation estimation. In this simple two-step estimation process, precipitation occurrence is first generated via a logistic regression model before estimate the amount of precipitation separately on wet days. This process generated the precipitation occurrence, amount, and spatial correlation effectively. A distributed hydrologic model (PRMS) was used for the impact analysis in daily time step simulation. Multiple simulations suggested noticeable differences between the input alternatives generated by three different interpolation schemes. Differences are shown in overall simulation error against the observations, degree of explained variability, and seasonal volumes. Simulated streamflows also showed different characteristics in mean, maximum, minimum, and peak flows. Given the same parameter optimization technique, LWP input showed least streamflow error in Alapaha basin and CMLR input showed least error (still very close to LWP) in Animas basin. All of the two-step interpolation inputs resulted in lower streamflow error compared to the directly interpolated inputs. ?? 2011 Springer-Verlag.

Effect of Various Retrogression Regimes on Aging Behavior and Precipitates Characterization of a High Zn-Containing Al-Zn-Mg-Cu Alloy

NASA Astrophysics Data System (ADS)

Wen, Kai; Xiong, Baiqing; Zhang, Yongan; Li, Zhihui; Li, Xiwu; Huang, Shuhui; Yan, Lizhen; Yan, Hongwei; Liu, Hongwei

2018-03-01

In the present work, the influence of various retrogression treatments on hardness, electrical conductivity and mechanical properties of a high Zn-containing Al-Zn-Mg-Cu alloy is investigated and several retrogression regimes subjected to a same strength level are proposed. The precipitates are qualitatively investigated by means of transmission electron microscopy (TEM) and high-resolution transmission electron microscopy techniques. Based on the matrix precipitate observations, the distributions of precipitate size and nearest inter-precipitate distance are extracted from bright-field TEM images projected along <110>Al orientation with the aid of an imaging analysis and an arithmetic method. The results show that GP zones and η' precipitates are the major precipitates and the precipitate size and its distribution range continuously enlarge with the retrogression regime expands to an extent of high temperature. The nearest inter-precipitate distance ranges obtained are quite the same and the average distance of nearest inter-precipitates show a slight increase. The influence of precipitates on mechanical properties is discussed through the interaction relationship between precipitates and dislocations.

Effect of Various Retrogression Regimes on Aging Behavior and Precipitates Characterization of a High Zn-Containing Al-Zn-Mg-Cu Alloy

NASA Astrophysics Data System (ADS)

Wen, Kai; Xiong, Baiqing; Zhang, Yongan; Li, Zhihui; Li, Xiwu; Huang, Shuhui; Yan, Lizhen; Yan, Hongwei; Liu, Hongwei

2018-05-01

In the present work, the influence of various retrogression treatments on hardness, electrical conductivity and mechanical properties of a high Zn-containing Al-Zn-Mg-Cu alloy is investigated and several retrogression regimes subjected to a same strength level are proposed. The precipitates are qualitatively investigated by means of transmission electron microscopy (TEM) and high-resolution transmission electron microscopy techniques. Based on the matrix precipitate observations, the distributions of precipitate size and nearest inter-precipitate distance are extracted from bright-field TEM images projected along <110>Al orientation with the aid of an imaging analysis and an arithmetic method. The results show that GP zones and η' precipitates are the major precipitates and the precipitate size and its distribution range continuously enlarge with the retrogression regime expands to an extent of high temperature. The nearest inter-precipitate distance ranges obtained are quite the same and the average distance of nearest inter-precipitates show a slight increase. The influence of precipitates on mechanical properties is discussed through the interaction relationship between precipitates and dislocations.

Retrospective Analog Year Analyses Using NASA Satellite Precipitation and Soil Moisture Data to Improve USDA's World Agricultural Supply and Demand Estimates

NASA Astrophysics Data System (ADS)

Teng, W. L.; Shannon, H.

2010-12-01

The USDA World Agricultural Outlook Board (WAOB) coordinates the development of the monthly World Agricultural Supply and Demand Estimates (WASDE) for the U.S. and major foreign producing countries. Given the significant effect of weather on crop progress, conditions, and production, WAOB prepares frequent agricultural weather assessments in the Global Agricultural Decision Support Environment (GLADSE). Because the timing of the precipitation is often as important as the amount, in their effects on crop production, WAOB frequently examines precipitation time series to estimate crop productivity. An effective method for such assessment is the use of analog year comparisons, where precipitation time series, based on surface weather stations, from several historical years are compared with the time series from the current year. Once analog years are identified, crop yields can be estimated for the current season based on observed yields from the analog years, because of the similarities in the precipitation patterns. In this study, NASA satellite precipitation and soil moisture time series are used to identify analog years. Given that soil moisture often has a more direct effect than does precipitation on crop water availability, the time series of soil moisture could be more effective than that of precipitation, in identifying those years with similar crop yields. Retrospective analyses of analogs will be conducted to determine any reduction in the level of uncertainty in identifying analog years, and any reduction in false negatives or false positives. The comparison of analog years could potentially be improved by quantifying the selection of analogs, instead of the current visual inspection method. Various approaches to quantifying are currently being evaluated. This study is part of a larger effort to improve WAOB estimates by integrating NASA remote sensing soil moisture observations and research results into GLADSE, including (1) the integration of the Land Parameter Retrieval Model (LPRM) soil moisture algorithm for operational production and (2) the assimilation of LPRM soil moisture into the USDA Environmental Policy Integrated Climate (EPIC) crop model.

Validation of non-stationary precipitation series for site-specific impact assessment: comparison of two statistical downscaling techniques

NASA Astrophysics Data System (ADS)

Mullan, Donal; Chen, Jie; Zhang, Xunchang John

2016-02-01

Statistical downscaling (SD) methods have become a popular, low-cost and accessible means of bridging the gap between the coarse spatial resolution at which climate models output climate scenarios and the finer spatial scale at which impact modellers require these scenarios, with various different SD techniques used for a wide range of applications across the world. This paper compares the Generator for Point Climate Change (GPCC) model and the Statistical DownScaling Model (SDSM)—two contrasting SD methods—in terms of their ability to generate precipitation series under non-stationary conditions across ten contrasting global climates. The mean, maximum and a selection of distribution statistics as well as the cumulative frequencies of dry and wet spells for four different temporal resolutions were compared between the models and the observed series for a validation period. Results indicate that both methods can generate daily precipitation series that generally closely mirror observed series for a wide range of non-stationary climates. However, GPCC tends to overestimate higher precipitation amounts, whilst SDSM tends to underestimate these. This infers that GPCC is more likely to overestimate the effects of precipitation on a given impact sector, whilst SDSM is likely to underestimate the effects. GPCC performs better than SDSM in reproducing wet and dry day frequency, which is a key advantage for many impact sectors. Overall, the mixed performance of the two methods illustrates the importance of users performing a thorough validation in order to determine the influence of simulated precipitation on their chosen impact sector.

High post-irradiation ductility thermomechanical treatment for precipitation strengthened austenitic alloys

DOEpatents

Laidler, James J.; Borisch, Ronald R.; Korenko, Michael K.

1982-01-01

A method for improving the post-irradiation ductility is described which prises a solution heat treatment following which the materials are cold worked. They are included to demonstrate the beneficial effect of this treatment on the swelling resistance and the ductility of these austenitic precipitation hardenable alloys.

Quantitative analysis of the effect of climate change and human activities on runoff in the Liujiang River Basin

NASA Astrophysics Data System (ADS)

LI, X.

2017-12-01

Abstract: As human basic and strategic natural resources, Water resources have received an unprecedented challenge under the impacts of global climate change. Analyzing the variation characteristics of runoff and the effect of climate change and human activities on runoff could provide the basis for the reasonable utilization and management of water resources. Taking the Liujiang River Basin as the research object, the discharge data of hydrological station and meteorological data at 24 meteorological stations in the Guangxi Province as the basis, the variation characteristics of runoff and precipitation in the Liujiang River Basin was analyzed, and the quantitatively effect of climate change and human activities on runoff was proposed. The results showed that runoff and precipitation in the Liujiang River Basin had an increasing trend from 1964 to 2006. Using the method of accumulative anomaly and the orderly cluster method, the runoff series was divided into base period and change period. BP - ANN model and sensitivity coefficient method were used for quantifying the influences of climate change and human activities on runoff. We found that the most important factor which caused an increase trend of discharges in the Liujiang River Basin was precipitation. Human activities were also important factors which influenced the intra-annual distribution of runoff. Precipitation had a more sensitive influence to runoff variation than potential evaporation in the Liujiang River Basin. Key words: Liujiang River Basin, climate change, human activities, BP-ANN, sensitivity coefficient method

Benchmarking a geostatistical procedure for the homogenisation of annual precipitation series

NASA Astrophysics Data System (ADS)

Caineta, Júlio; Ribeiro, Sara; Henriques, Roberto; Soares, Amílcar; Costa, Ana Cristina

2014-05-01

The European project COST Action ES0601, Advances in homogenisation methods of climate series: an integrated approach (HOME), has brought to attention the importance of establishing reliable homogenisation methods for climate data. In order to achieve that, a benchmark data set, containing monthly and daily temperature and precipitation data, was created to be used as a comparison basis for the effectiveness of those methods. Several contributions were submitted and evaluated by a number of performance metrics, validating the results against realistic inhomogeneous data. HOME also led to the development of new homogenisation software packages, which included feedback and lessons learned during the project. Preliminary studies have suggested a geostatistical stochastic approach, which uses Direct Sequential Simulation (DSS), as a promising methodology for the homogenisation of precipitation data series. Based on the spatial and temporal correlation between the neighbouring stations, DSS calculates local probability density functions at a candidate station to detect inhomogeneities. The purpose of the current study is to test and compare this geostatistical approach with the methods previously presented in the HOME project, using surrogate precipitation series from the HOME benchmark data set. The benchmark data set contains monthly precipitation surrogate series, from which annual precipitation data series were derived. These annual precipitation series were subject to exploratory analysis and to a thorough variography study. The geostatistical approach was then applied to the data set, based on different scenarios for the spatial continuity. Implementing this procedure also promoted the development of a computer program that aims to assist on the homogenisation of climate data, while minimising user interaction. Finally, in order to compare the effectiveness of this methodology with the homogenisation methods submitted during the HOME project, the obtained results were evaluated using the same performance metrics. This comparison opens new perspectives for the development of an innovative procedure based on the geostatistical stochastic approach. Acknowledgements: The authors gratefully acknowledge the financial support of "Fundação para a Ciência e Tecnologia" (FCT), Portugal, through the research project PTDC/GEO-MET/4026/2012 ("GSIMCLI - Geostatistical simulation with local distributions for the homogenization and interpolation of climate data").

Evaluation of multiple precipitation products across Mainland China using the triple collocation method without ground truth

NASA Astrophysics Data System (ADS)

Tang, G.; Li, C.; Hong, Y.; Long, D.

2017-12-01

Proliferation of satellite and reanalysis precipitation products underscores the need to evaluate their reliability, particularly over ungauged or poorly gauged regions. However, it is really challenging to perform such evaluations over regions lacking ground truth data. Here, using the triple collocation (TC) method that is capable of evaluating relative uncertainties in different products without ground truth, we evaluate five satellite-based precipitation products and comparatively assess uncertainties in three types of independent precipitation products, e.g., satellite-based, ground-observed, and model reanalysis over Mainland China, including a ground-based precipitation dataset (the gauge based daily precipitation analysis, CGDPA), the latest version of the European reanalysis agency reanalysis (ERA-interim) product, and five satellite-based products (i.e., 3B42V7, 3B42RT of TMPA, IMERG, CMORPH-CRT, PERSIANN-CDR) on a regular 0.25° grid at the daily timescale from 2013 to 2015. First, the effectiveness of the TC method is evaluated by comparison with traditional methods based on ground observations in a densely gauged region. Results show that the TC method is reliable because the correlation coefficient (CC) and root mean square error (RMSE) are close to those based on the traditional method with a maximum difference only up to 0.08 and 0.71 (mm/day) for CC and RMSE, respectively. Then, the TC method is applied to Mainland China and the Tibetan Plateau (TP). Results indicate that: (1) the overall performance of IMERG is better than the other satellite products over Mainland China; (2) over grid cells without rain gauges in the TP, IMERG and ERA show better performance than CGDPA, indicating the potential of remote sensing and reanalysis data over these regions and the inherent uncertainty of CGDPA due to interpolation using sparsely gauged data; (3) both TMPA-3B42 and CMORPH-CRT have some unexpected CC values over certain grid cells that contain water bodies, reaffirming the overestimation of precipitation over inland water bodies. Overall, the TC method provides not only reliable cross-validation results of precipitation estimates over Mainland China but also a new perspective as to compressively assess multi-source precipitation products, particularly over poorly gauged regions.

Impacts of precipitation and potential evapotranspiration patterns on downscaling soil moisture in regions with large topographic relief

NASA Astrophysics Data System (ADS)

Cowley, Garret S.; Niemann, Jeffrey D.; Green, Timothy R.; Seyfried, Mark S.; Jones, Andrew S.; Grazaitis, Peter J.

2017-02-01

Soil moisture can be estimated at coarse resolutions (>1 km) using satellite remote sensing, but that resolution is poorly suited for many applications. The Equilibrium Moisture from Topography, Vegetation, and Soil (EMT+VS) model downscales coarse-resolution soil moisture using fine-resolution topographic, vegetation, and soil data to produce fine-resolution (10-30 m) estimates of soil moisture. The EMT+VS model performs well at catchments with low topographic relief (≤124 m), but it has not been applied to regions with larger ranges of elevation. Large relief can produce substantial variations in precipitation and potential evapotranspiration (PET), which might affect the fine-resolution patterns of soil moisture. In this research, simple methods to downscale temporal average precipitation and PET are developed and included in the EMT+VS model, and the effects of spatial variations in these variables on the surface soil moisture estimates are investigated. The methods are tested against ground truth data at the 239 km2 Reynolds Creek watershed in southern Idaho, which has 1145 m of relief. The precipitation and PET downscaling methods are able to capture the main features in the spatial patterns of both variables. The space-time Nash-Sutcliffe coefficients of efficiency of the fine-resolution soil moisture estimates improve from 0.33 to 0.36 and 0.41 when the precipitation and PET downscaling methods are included, respectively. PET downscaling provides a larger improvement in the soil moisture estimates than precipitation downscaling likely because the PET pattern is more persistent through time, and thus more predictable, than the precipitation pattern.

The Effects of Secondary Oxides on Copper-Based Catalysts for Green Methanol Synthesis.

PubMed

Hayward, James S; Smith, Paul J; Kondrat, Simon A; Bowker, Michael; Hutchings, Graham J

2017-05-10

Catalysts for methanol synthesis from CO 2 and H 2 have been produced by two main methods: co-precipitation and supercritical anti-solvent (SAS) precipitation. These two methods are compared, along with the behaviour of copper supported on Zn, Mg, Mn, and Ce oxides. Although the SAS method produces initially active material with high Cu specific surface area, they appear to be unstable during reaction losing significant amounts of surface area and hence activity. The CuZn catalysts prepared by co-precipitation, however, showed much greater thermal and reactive stability than the other materials. There appeared to be the usual near-linear dependence of activity upon Cu specific area, though the initial performance relationship was different from that post-reaction, after some loss of surface area. The formation of the malachite precursor, as reported before, is important for good activity and stability, whereas if copper oxides are formed during the synthesis and ageing process, then a detrimental effect on these properties is seen.

The Effects of Secondary Oxides on Copper‐Based Catalysts for Green Methanol Synthesis

PubMed Central

Hayward, James S.; Smith, Paul J.; Kondrat, Simon A.; Bowker, Michael

2017-01-01

Abstract Catalysts for methanol synthesis from CO2 and H2 have been produced by two main methods: co‐precipitation and supercritical anti‐solvent (SAS) precipitation. These two methods are compared, along with the behaviour of copper supported on Zn, Mg, Mn, and Ce oxides. Although the SAS method produces initially active material with high Cu specific surface area, they appear to be unstable during reaction losing significant amounts of surface area and hence activity. The CuZn catalysts prepared by co‐precipitation, however, showed much greater thermal and reactive stability than the other materials. There appeared to be the usual near‐linear dependence of activity upon Cu specific area, though the initial performance relationship was different from that post‐reaction, after some loss of surface area. The formation of the malachite precursor, as reported before, is important for good activity and stability, whereas if copper oxides are formed during the synthesis and ageing process, then a detrimental effect on these properties is seen. PMID:28706570

Estimating Watershed-Averaged Precipitation and Evapotranspiration Fluxes using Streamflow Measurements in a Semi-Arid, High Altitude Montane Catchment

NASA Astrophysics Data System (ADS)

Herrington, C.; Gonzalez-Pinzon, R.

2014-12-01

Streamflow through the Middle Rio Grande Valley is largely driven by snowmelt pulses and monsoonal precipitation events originating in the mountain highlands of New Mexico (NM) and Colorado. Water managers rely on results from storage/runoff models to distribute this resource statewide and to allocate compact deliveries to Texas under the Rio Grande Compact agreement. Prevalent drought conditions and the added uncertainty of climate change effects in the American southwest have led to a greater call for accuracy in storage model parameter inputs. While precipitation and evapotranspiration measurements are subject to scaling and representativeness errors, streamflow readings remain relatively dependable and allow watershed-average water budget estimates. Our study seeks to show that by "Doing Hydrology Backwards" we can effectively estimate watershed-average precipitation and evapotranspiration fluxes in semi-arid landscapes of NM using fluctuations in streamflow data alone. We tested this method in the Valles Caldera National Preserve (VCNP) in the Jemez Mountains of central NM. This method will be further verified by using existing weather stations and eddy-covariance towers within the VCNP to obtain measured values to compare against our model results. This study contributes to further validate this technique as being successful in humid and semi-arid catchments as the method has already been verified as effective in the former setting.

Identification of critical process variables affecting particle size following precipitation using a supercritical fluid.

PubMed

Sacha, Gregory A; Schmitt, William J; Nail, Steven L

2006-01-01

The critical processing parameters affecting average particle size, particle size distribution, yield, and level of residual carrier solvent using the supercritical anti-solvent method (SAS) were identified. Carbon dioxide was used as the supercritical fluid. Methylprednisolone acetate was used as the model solute in tetrahydrofuran. Parameters examined included pressure of the supercritical fluid, agitation rate, feed solution flow rate, impeller diameter, and nozzle design. Pressure was identified as the most important process parameter affecting average particle size, either through the effect of pressure on dispersion of the feed solution into the precipitation vessel or through the effect of pressure on solubility of drug in the CO2/organic solvent mixture. Agitation rate, impeller diameter, feed solution flow rate, and nozzle design had significant effects on particle size, which suggests that dispersion of the feed solution is important. Crimped HPLC tubing was the most effective method of introducing feed solution into the precipitation vessel, largely because it resulted in the least amount of clogging during the precipitation. Yields of 82% or greater were consistently produced and were not affected by the processing variables. Similarly, the level of residual solvent was independent of the processing variables and was present at 0.0002% wt/wt THF or less.

Spatial distribution of precipitation extremes in Norway

NASA Astrophysics Data System (ADS)

Verpe Dyrrdal, Anita; Skaugen, Thomas; Lenkoski, Alex; Thorarinsdottir, Thordis; Stordal, Frode; Førland, Eirik J.

2015-04-01

Estimates of extreme precipitation, in terms of return levels, are crucial in planning and design of important infrastructure. Through two separate studies, we have examined the levels and spatial distribution of daily extreme precipitation over catchments in Norway, and hourly extreme precipitation in a point. The analyses were carried out through the development of two new methods for estimating extreme precipitation in Norway. For daily precipitation we fit the Generalized Extreme Value (GEV) distribution to areal time series from a gridded dataset, consisting of daily precipitation during the period 1957-today with a resolution of 1x1 km². This grid-based method is more objective and less manual and time-consuming compared to the existing method at MET Norway. In addition, estimates in ungauged catchments are easier to obtain, and the GEV approach includes a measure of uncertainty, which is a requirement in climate studies today. Further, we go into depth on the debated GEV shape parameter, which plays an important role for longer return periods. We show that it varies according to dominating precipitation types, having positive values in the southeast and negative values in the southwest. We also find indications that the degree of orographic enhancement might affect the shape parameter. For hourly precipitation, we estimate return levels on a 1x1 km² grid, by linking GEV distributions with latent Gaussian fields in a Bayesian hierarchical model (BHM). Generalized linear models on the GEV parameters, estimated from observations, are able to incorporate location-specific geographic and meteorological information and thereby accommodate these effects on extreme precipitation. Gaussian fields capture additional unexplained spatial heterogeneity and overcome the sparse grid on which observations are collected, while a Bayesian model averaging component directly assesses model uncertainty. We find that mean summer precipitation, mean summer temperature, latitude, longitude, mean annual precipitation and elevation are good covariate candidates for hourly precipitation in our model. Summer indices succeed because hourly precipitation extremes often occur during the convective season. The spatial distribution of hourly and daily precipitation differs in Norway. Daily precipitation extremes are larger along the southwestern coast, where large-scale frontal systems dominate during fall season and the mountain ridge generates strong orographic enhancement. The largest hourly precipitation extremes are mostly produced by intense convective showers during summer, and are thus found along the entire southern coast, including the Oslo-region.

Comparison of conventional and bio-treated methods as dust suppressants.

PubMed

Naeimi, Maryam; Chu, Jian

2017-10-01

Dust is an environmental, geotechnical, health, and economical hazard. Fugitive dust emanating along transportation systems such as roads, railways, and airports especially can have significant impacts on health, safety, material loss, cost of maintenance, and interfere with the facilities. Quantitative studies on the effectiveness of the proper dust palliatives and their environmental impact have been studied with a number of biological and chemical methods. The objective of this study was to establish a method for using the microbial Induced calcium carbonate precipitation (MICP) approach to reduce the percent of mass loss against erosive force of wind regarding to the concentration and characteristics of aggregate used, climate, and traffic amounts. The results of this study showed that the required precipitation for dust control of sand by 70% is less than 15 g CaCO 3 /m 2 between sand grains in bio-treated sand. The wind tunnel test results of this study also indicate that the effectiveness of the bio-treatment method for dust control depends on many variables, such as the percent of precipitated calcium carbonate and tensile strength.

a Study of Oxygen Precipitation in Heavily Doped Silicon.

NASA Astrophysics Data System (ADS)

Graupner, Robert Kurt

Gettering of impurities with oxygen precipitates is widely used during the fabrication of semiconductors to improve the performance and yield of the devices. Since the effectiveness of the gettering process is largely dependent on the initial interstitial oxygen concentration, accurate measurements of this parameter are of considerable importance. Measurements of interstitial oxygen following thermal cycles are required for development of semiconductor fabrication processes and for research into the mechanisms of oxygen precipitate nucleation and growth. Efforts by industrial associations have led to the development of standard procedures for the measurement of interstitial oxygen in wafers. However practical oxygen measurements often do not satisfy the requirements of such standard procedures. An additional difficulty arises when the silicon wafer has a low resitivity (high dopant concentration). In such cases the infrared light used for the measurement is severely attenuated by the electrons of holes introduced by the dopant. Since such wafers are the substrates used for the production of widely used epitaxial wafers, this measurement problem is economically important. Alternative methods such as Secondary Ion Mass Spectroscopy or Gas Fusion Analysis have been developed to measure oxygen in these cases. However, neither of these methods is capable of distinguishing interstitial oxygen from precipitated oxygen as required for precipitation studies. In addition to the commercial interest in heavily doped silicon substrates, they are also of interest for research into the role of point defects in nucleation and precipitation processes. Despite considerable research effort, there is still disagreement concerning the type of point defect and its role in semiconductor processes. Studies of changes in the interstitial oxygen concentration of heavily doped and lightly doped silicon wafers could help clarify the role of point defects in oxygen nucleation and precipitation processes. This could lead to more effective control and use of oxygen precipitation for gettering. One of the principal purposes of this thesis is the extension of the infrared interstitial oxygen measurement technique to situations outside the measurement capacities of the standard technique. These situations include silicon slices exhibiting interfering precipitate absorption bands and heavily doped n-type silicon wafers. A new method is presented for correcting for the effect of multiple reflections in silicon wafers with optically rough surfaces. The technique for the measurement of interstitial oxygen in heavily doped n-type wafers is then used to perform a comparative study of oxygen precipitation in heavily antimony doped (.035 ohm-cm) silicon and lightly doped p-type silicon. A model is presented to quantitatively explain the observed suppression of defect formation in heavily doped n-type wafers.

Calcium carbonate scale control, effect of material and inhibitors.

PubMed

Macadam, J; Parsons, S A

2004-01-01

This paper focuses on developing a reproducible method for reducing calcium carbonate scale formation on heated surfaces where scaling can cause serious problems. It is known that calcium carbonate precipitation is sensitive to impurity ions, such as iron and zinc, even at trace concentration levels. In this paper two sets of experiments are reported. The first experiments were undertaken to investigate the effect of zinc, copper and iron dosing on CaCO3 nucleation and precipitation. Results from the experiments showed that the most effective inhibitor of CaCO3 precipitation was zinc and the effect was linked to dose levels and temperature. Copper and iron had little effect on precipitation in the dose range investigated. The second trial was undertaken to translate the precipitation data to scale formation. These tests were undertaken at 70 degrees C. 5 mg x L(-1) zinc dose reduced the scale formation by 35%. The effect of iron on calcium carbonate scaling rate was not significant. The physical nature of the material on which the scale is formed also influences the scaling. The scaling experiment was also used to investigate the effect of different surface material (stainless steel, copper and aluminium) on CaCO3 scale formation. Copper surface scaled the most.

Method and apparatus for measuring coupled flow, transport, and reaction processes under liquid unsaturated flow conditions

DOEpatents

McGrail, Bernard P.; Martin, Paul F.; Lindenmeier, Clark W.

1999-01-01

The present invention is a method and apparatus for measuring coupled flow, transport and reaction processes under liquid unsaturated flow conditions. The method and apparatus of the present invention permit distinguishing individual precipitation events and their effect on dissolution behavior isolated to the specific event. The present invention is especially useful for dynamically measuring hydraulic parameters when a chemical reaction occurs between a particulate material and either liquid or gas (e.g. air) or both, causing precipitation that changes the pore structure of the test material.

Impact of the North Atlantic Oscillation on winter precipitation totals in Slovakia

NASA Astrophysics Data System (ADS)

Leskova, Livia; Stastny, Pavel

2013-04-01

The North Atlantic Oscillation (NAO) is the most important circulation mode in the Northern Hemisphere, which impacts climate in Europe in various ways. The strongest impacts of oscillation on air temperature and precipitation regime are detected in Scandinavia and Mediterranean region, but impacts have opposite effect. Therefore, assessment of the relation between NAO and precipitation totals seems to be interesting in Slovakia, because of the country location in the centre between above mentioned regions. Our former research detected only the relation between NAO and a winter precipitation totals in Slovakia. More detailed aspects of this relation is analysed in this paper. A correlation method was used at two resolution levels, which detected opposite spatial impact of NAO on above mentioned seasonal precipitation. The first generalised level was based on the precipitation regions, which were distinguished on the base of characteristic precipitation regime of individual regions. The second level was more detailed and the correlation method was applied on data of every individual rain gauge station from the set of 202 rain gauge stations with complete data for period 1901 - 2010 in Slovakia. In the northern part of the country (Orava and Kysuce regions), there was found the positive correlation. Increase in the winter precipitation totals was recorded in the same regions and general precipitation trend in this area was similar to the trend in used Hurrell oscillation index. It means, following the increasing trend in oscillation course, we can also expect the increase in precipitation totals in these regions in the near future. In a southward direction, this correlation changed to the negative values and the most negative correlation coefficients were reached in the lowland regions (Podunajská and Východoslovenská nížina) and in the region of Juhoslovenská kotlina. This last mentioned region is located in multiple precipitation shadow of Carpathians, whereas the precipitation shadow is lower in other regions. Therefore, we suppose, the impact of NAO is strongly influenced by barrier effect of Carpathian Mountains. It can also be expected the important impact of Mediterranean oscillation in the last mentioned regions. ACKNOWLEDGEMENT The article was prepared with the support of grant VEGA 1/1155/12.

PROCESS FOR PRODUCING URANIUM TETRAFLUORIDE

DOEpatents

Harvey, B.G.

1954-09-14

>This patent relates to improvements in the method for producing uranium tetrafluoride by treating an aqueous solutlon of a uranyl salt at an elevated temperature with a reducing agent effective in acld solutlon in the presence of hydrofluoric acid. Uranium tetrafluoride produced this way frequentiy contains impurities in the raw material serving as the source of uranium. Uranium tetrafluoride much less contaminated with impurities than when prepared by the above method can be prepared from materials containing such impurities by first adding a small proportion of reducing agent so as to cause a small fraction, for example 1 to 5% of the uranium tetrafluoride to be precipitated, rejecting such precipitate, and then precipitating and recovering the remainder of the uranium tetrafluoride.

Comparative study of two methods of fractionation bromelain from pineapple core extract (Ananas comosus)

NASA Astrophysics Data System (ADS)

Febriani, K.; Wahyuni, I.; Setiasih, S.; Hudiyono, S.

2017-07-01

The enzyme can be purified by fractional precipitation. This can be done by salt or organic solvent. In this research, purification of bromelain from pineapple core by fractional precipitation was done by 2 compounds, ammonium sulfate, and ethanol. Fractional precipitation by ammonium sulfate proved to be more effective as it yielded a higher specific activity. Specific activity by ethanol and ammonium sulfate is 4.6480 U/mg at 0-60 % saturation and 8.2243 U/mg at 50-80 % saturation.

Investigation of Nd xY 0.25-xZr 0.75O 1.88 inert matrix fuel materials made by a co-precipitation synthetic route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, John R.; Grosvenor, Andrew P.

Yttria-stabilized zirconia (YSZ) is a material that we are considering in our inert matrix fuel nuclear reactors, but a complete characterization of these materials is required for them to be licensed for use. A series of NdxY0.25–xZr0.75O1.88 materials have been synthesized using a co-precipitation method, and the thermal stability of these materials has been studied by annealing them at 1400 and 1500 °C. (Nd was used as surrogate for Am.) The long-range and local structures of the materials were characterized via powder X-ray diffraction, scanning electron microscopy, wavelength dispersive spectroscopy, and X-ray absorption spectroscopy at the Zr K- and Ymore » K-edges. These results were compared with the previous characterization of Nd-YSZ materials synthesized using a ceramic method. Moreover, the results indicated that the ordering in the local metal–oxygen polyhedral remains relatively unaffected by the synthetic method, but there was increased long-range disorder in the materials prepared by the co-precipitation method. Further, it was found that the materials produced by the co-precipitation method were unexpectedly unstable when annealed at high temperature. This study highlights the importance of determining the effect of synthetic method on material properties and demonstrates how the co-precipitation route could be used to produce inert matrix fuels.« less

Precipitation and Air Temperature Impact on Seasonal Variations of Groundwater Levels

NASA Astrophysics Data System (ADS)

Vitola, Ilva; Vircavs, Valdis; Abramenko, Kaspars; Lauva, Didzis; Veinbergs, Arturs

2012-12-01

The aim of this study is to clarify seasonal effects of precipitation and temperature on groundwater level changes in monitoring stations of the Latvia University of Agriculture - Mellupīte, Bērze and Auce. Groundwater regime and level fluctuations depend on climatic conditions such as precipitation intensity, evapotranspiration, surface runoff and drainage, as well as other hydrological factors. The relationship between precipitation, air temperature and groundwater level fluctuations could also lead and give different perspective of possible changes in groundwater quality. Using mathematical statistics and graphic-analytic methods it is concluded that autumn and winter precipitation has the dominant impact on groundwater level fluctuations, whereas spring and summer season fluctuations are more dependent on the air temperature.

The coincidence of daily rainfall events in Liberia, Costa Rica and tropical cyclones in the Caribbean basin

NASA Astrophysics Data System (ADS)

Waylen, Peter R.; Harrison, Michael

2005-10-01

The occurrence of tropical cyclones in the Caribbean and North Atlantic basins has been previously noted to have a significant effect both upon individual hydro-climatological events as well as on the quantity of annual precipitation experienced along the Pacific flank of Central America. A methodology for examining the so-called indirect effects of tropical cyclones (i.e. those effects resulting from a tropical cyclone at a considerable distance from the area of interest) on a daily rainfall record is established, which uses a variant of contingency table analysis. The method is tested using a single station on the Pacific slope of Costa Rica. Employing daily precipitation records from Liberia, north-western Costa Rica (1964-1995), and historic storm tracks of tropical cyclones in the North Atlantic, it is determined that precipitation falling in coincidence with the passage of tropical depressions, tropical storms, and hurricanes accounts for approximately 15% of average annual precipitation. The greatest effects are associated with storms passing within 1300 km of the precipitation station, and are most apparent in the increased frequency of daily rainfall totals in the range of 40-60 mm, rather than in the largest daily totals. The complexity and nonstationarity of factors affecting precipitation in this region are reflected in the decline in the number of tropical cyclones and their significance to annual precipitation totals after 1980, simultaneous to an increase in annual precipitation totals. The methodology employed in this study is shown to be a useful tool in illuminating the indirect effects of tropical cyclones in the region, with the potential for application in other areas.

The strength and dislocation microstructure evolution in superalloy microcrystals

NASA Astrophysics Data System (ADS)

Hussein, Ahmed M.; Rao, Satish I.; Uchic, Michael D.; Parthasarathay, Triplicane A.; El-Awady, Jaafar A.

2017-02-01

In this work, the evolution of the dislocations microstructure in single crystal two-phase superalloy microcrystals under monotonic loading has been studied using the three-dimensional discrete dislocation dynamics (DDD) method. The DDD framework has been extended to properly handle the collective behavior of dislocations and their interactions with large collections of arbitrary shaped precipitates. Few constraints are imposed on the initial distribution of the dislocations or the precipitates, and the extended DDD framework can support experimentally-obtained precipitate geometries. Full tracking of the creation and destruction of anti-phase boundaries (APB) is accounted for. The effects of the precipitate volume fraction, APB energy, precipitate size, and crystal size on the deformation of superalloy microcrystals have been quantified. Correlations between the precipitate microstructure and the dominant deformation features, such as dislocation looping versus precipitate shearing, are also discussed. It is shown that the mechanical strength is independent of the crystal size, increases linearly with increasing the volume fraction, follows a near square-root relationship with the APB energy and an inverse square-root relationship with the precipitate size. Finally, the flow strength in simulations having initial dislocation pair sources show a flow strength that is about one half of that predicted from simulations starting with single dislocation sources. The method developed can be used, with minimal extensions, to simulate dislocation microstructure evolution in general multiphase materials.

Measurement of precipitation using lysimeters

NASA Astrophysics Data System (ADS)

Fank, Johann; Klammler, Gernot

2013-04-01

Austria's alpine foothill aquifers contain important drinking water resources, but are also used intensively for agricultural production. These groundwater bodies are generally recharged by infiltrating precipitation. A sustainable water resources management of these aquifers requires quantifying real evapotranspiration (ET), groundwater recharge (GR), precipitation (P) and soil water storage change (ΔS). While GR and ΔS can be directly measured by weighable lysimeters and P by separate precipitation gauges, ET is determined by solving the climatic water balance ET = P GR ± ΔS. According to WMO (2008) measurement of rainfall is strongly influenced by precipitation gauge errors. Most significant errors result from wind loss, wetting loss, evaporation loss, and due to in- and out-splashing of water. Measuring errors can be reduced by a larger area of the measuring gaugés surface and positioning the collecting vessel at ground level. Modern weighable lysimeters commonly have a surface of 1 m², are integrated into their typical surroundings of vegetation cover (to avoid oasis effects) and allow scaling the mass change of monolithic soil columns in high measuring accuracy (0.01 mm water equivalent) and high temporal resolution. Thus, also precipitation can be quantified by measuring the positive mass changes of the lysimeter. According to Meissner et al. (2007) also dew, fog and rime can be determined by means of highly precise weighable lysimeters. Furthermore, measuring precipitation using lysimeters avoid common measuring errors (WMO 2008) at point scale. Though, this method implicates external effects (background noise, influence of vegetation and wind) which affect the mass time series. While the background noise of the weighing is rather well known and can be filtered out of the mass time series, the influence of wind, which blows through the vegetation and affects measured lysimeter mass, cannot be corrected easily since there is no clear relation between wind speeds and the measured outliers of lysimeter mass. Moreover, the influence of wind seems to be varying for different lysimeters. At the agricultural test site Wagna, Austria, two precipitation gauges in high temporal resolution (weighing-recording gauge and tipping-bucket gauge; both 200 cm² surface; measuring height 1.5 m) are installed. Furthermore, mass time series of various lysimeters cultivated with different vegetation is also available for the same location. Appropriate methods to compensate the influence of wind on measuring precipitation using lysimeters are investigated and results between the different measuring devices are compared. Results show that precipitation measured with lysimeters is generally higher, especially compared to the weighing-recording gauge. In addition it is detected that also the data interval of lysimeter mass time series used for quantifying precipitation (e.g., 1 day, 1 hour, 30 minutes, 10 minutes) is a crucial factor and influences the result. Summarizing, the potential of using highly precise weighable lysimeters for measuring precipitation at the point scale is rather high. However, methods used to compensate external effects on lysimeter weighing have to be enhanced for a global application of using lysimeters as precipitation gauges. Meissner, R., J. Seeger, H. Rupp, M. Seyfarth & H. Borg, 2007: Measurement of dew, fog, and rime with a high-precision gravitation Lysimeter. J. Plant Nutr. Soil Sci. 2007, 170, p. 335-344. WMO (World Meteorological Organization), 2008. Guide to Meteorological Instruments and Methods of Observation. WMO-No. 8, 140 pp.

Effects of anthropogenic activity emerging as intensified extreme precipitation over China

NASA Astrophysics Data System (ADS)

Li, Huixin; Chen, Huopo; Wang, Huijun

2017-07-01

This study aims to provide an assessment of the effects of anthropogenic (ANT) forcings and other external factors on observed increases in extreme precipitation over China from 1961 to 2005. Extreme precipitation is represented by the annual maximum 1 day precipitation (RX1D) and the annual maximum 5 day consecutive precipitation (RX5D), and these variables are investigated using observations and simulations from the Coupled Model Intercomparison Project phase 5. The analyses mainly focus on the probability-based index (PI), which is derived from RX1D and RX5D by fitting generalized extreme value distributions. The results indicate that the simulations that include the ANT forcings provide the best representation of the spatial and temporal characteristics of extreme precipitation over China. We use the optimal fingerprint method to obtain the univariate and multivariate fingerprints of the responses to external forcings. The results show that only the ANT forcings are detectable at a 90% confidence level, both individually and when natural forcings are considered simultaneously. The impact of the forcing associated with greenhouse gases (GHGs) is also detectable in RX1D, but its effects cannot be separated from those of combinations of forcings that exclude the GHG forcings in the two-signal analyses. Besides, the estimated changes of PI, extreme precipitation, and events with a 20 year return period under nonstationary climate states are potentially attributable to ANT or GHG forcings, and the relationships between extreme precipitation and temperature from ANT forcings show agreement with observations.

Short-range quantitative precipitation forecasting using Deep Learning approaches

NASA Astrophysics Data System (ADS)

Akbari Asanjan, A.; Yang, T.; Gao, X.; Hsu, K. L.; Sorooshian, S.

2017-12-01

Predicting short-range quantitative precipitation is very important for flood forecasting, early flood warning and other hydrometeorological purposes. This study aims to improve the precipitation forecasting skills using a recently developed and advanced machine learning technique named Long Short-Term Memory (LSTM). The proposed LSTM learns the changing patterns of clouds from Cloud-Top Brightness Temperature (CTBT) images, retrieved from the infrared channel of Geostationary Operational Environmental Satellite (GOES), using a sophisticated and effective learning method. After learning the dynamics of clouds, the LSTM model predicts the upcoming rainy CTBT events. The proposed model is then merged with a precipitation estimation algorithm termed Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) to provide precipitation forecasts. The results of merged LSTM with PERSIANN are compared to the results of an Elman-type Recurrent Neural Network (RNN) merged with PERSIANN and Final Analysis of Global Forecast System model over the states of Oklahoma, Florida and Oregon. The performance of each model is investigated during 3 storm events each located over one of the study regions. The results indicate the outperformance of merged LSTM forecasts comparing to the numerical and statistical baselines in terms of Probability of Detection (POD), False Alarm Ratio (FAR), Critical Success Index (CSI), RMSE and correlation coefficient especially in convective systems. The proposed method shows superior capabilities in short-term forecasting over compared methods.

Does Temperature Modify the Effects of Rain and Snow Precipitation on Road Traffic Injuries?

PubMed Central

Lee, Won-Kyung; Lee, Hye-Ah; Hwang, Seung-sik; Kim, Ho; Lim, Youn-Hee; Hong, Yun-Chul; Ha, Eun-Hee; Park, Hyesook

2015-01-01

Background There are few data on the interaction between temperature and snow and rain precipitation, although they could interact in their effects on road traffic injuries. Methods The integrated database of the Korea Road Traffic Authority was used to calculate the daily frequency of road traffic injuries in Seoul. Weather data included rain and snow precipitation, temperature, pressure, and fog from May 2007 to December 2011. Precipitation of rain and snow were divided into nine and six temperature range categories, respectively. The interactive effects of temperature and rain and snow precipitation on road traffic injuries were analyzed using a generalized additive model with a Poisson distribution. Results The risk of road traffic injuries during snow increased when the temperature was below freezing. Road traffic injuries increased by 6.6% when it was snowing and above 0°C, whereas they increased by 15% when it was snowing and at or below 0°C. In terms of heavy rain precipitation, moderate temperatures were related to an increased prevalence of injuries. When the temperature was 0–20°C, we found a 12% increase in road traffic injuries, whereas it increased by 8.5% and 6.8% when it was <0°C and >20°C, respectively. The interactive effect was consistent across the traffic accident subtypes. Conclusions The effect of adverse weather conditions on road traffic injuries differed depending on the temperature. More road traffic injuries were related to rain precipitation when the temperature was moderate and to snow when it was below freezing. PMID:26073021

Spatio-temporal changes in precipitation over Beijing-Tianjin-Hebei region, China

NASA Astrophysics Data System (ADS)

Zhao, Na; Yue, Tianxiang; Li, Han; Zhang, Lili; Yin, Xiaozhe; Liu, Yi

2018-04-01

Changes in precipitation have a large effect on human society and are of primary importance for many scientific fields such as hydrology, agriculture and eco-environmental sciences. The present study intended to investigate the spatio-temporal characteristics of precipitation in Beijing-Tianjin-Hebei (BTH) region by using 316 meteorological stations during the period 1965-2014. Geographical Weighted Regression (GWR) method and High Accuracy Surface Modeling (HASM) method were applied to produce the precipitation patterns at different time scales. Mann-Kendall (MK) statistical test was applied to analyze the precipitation temporal variations. Results indicated that annual precipitation over the past 50 years appeared to be a non-periodic oscillation phenomenon; the number of wet years was approximately the same as that of dry years; significant positive trends were observed in spring during 1978-2014 and summer during 1996-2014; on the whole, precipitation in May, June, September, and December showed increasing trends at the 95% confidence level; and significant positive trends were also identified in July during 2000-2013 and August during 1997-2010, while slight decreasing trends were observed in February and November. Summer (June, July, and August) was the wettest season, accounting for 68.73% of annual totals in BTH. In general, northeastern BTH received the highest range of precipitation while northwestern area had the lowest. It was found that precipitation variation in this region had been closely linked to latitude, Digital Elevation Model (DEM), distance to the sea, and urbanization rate. In addition, land use played an important role in the decadal precipitation changes in BTH.

Characteristics of people with self-reported stress-precipitated seizures.

PubMed

Privitera, Michael; Walters, Michael; Lee, Ikjae; Polak, Emily; Fleck, Adrienne; Schwieterman, Donna; Haut, Sheryl R

2014-12-01

Stress is the most common patient-reported seizure precipitant. We aimed to determine mood and epilepsy characteristics of people who report stress-precipitated seizures. Sequential patients at a tertiary epilepsy center were surveyed about stress as a seizure precipitant. We asked whether acute (lasting minutes-hours) or chronic (lasting days-months) stress was a seizure precipitant, whether stress reduction had been tried, and what effect stress reduction had on seizure frequency. We collected information on antiepileptic drugs, history of depression and anxiety disorder, prior or current treatment for depression or anxiety, and scores on the Neurological Disorders Depression Inventory (NDDI-E) and Generalized Anxiety Disorders-7 (GAD-7) instruments, which are administered at every visit in our Epilepsy Center. We also asked whether respondents thought that they could predict their seizures to determine if stress as a seizure precipitant was correlated with seizure self-prediction. Two hundred sixty-six subjects were included: 219 endorsed stress as a seizure precipitant [STRESS (+)] and 47 did not [STRESS (-)]. Among STRESS (+) subjects, 85% endorsed chronic stress as a seizure precipitant, and 68% endorsed acute stress as a seizure precipitant. In STRESS (+) subjects, 57% had used some type of relaxation or stress reduction method (most commonly yoga, exercise and meditation), and, of those who tried, 88% thought that these methods improved seizures. Among STRESS (-) subjects, 25% had tried relaxation or stress reduction, and 71% thought that seizures improved. Although univariate analysis showed multiple associations with stress as a seizure precipitant, in the multivariable logistic regression, only the GAD-7 score was associated with STRESS (+) (OR = 1.18 [1.03-1.35], p = 0.017). Subjects who reported stress as a seizure precipitant were more likely to report an ability to self-predict seizures (p < 0.001). Stress-precipitated seizures are commonly reported by patients, may be associated with either acute stress or chronic stress, and are associated with higher scores on anxiety tests. Patients frequently use stress reduction methods to self-treat and report high success rates. A prospective, randomized trial of stress reduction for seizures is indicated. Copyright © 2014 Elsevier Inc. All rights reserved.

Method for improving separation of carbohydrates from wood pulping and wood or biomass hydrolysis liquors

DOEpatents

Griffith, William Louis; Compere, Alicia Lucille; Leitten, Jr., Carl Frederick

2010-04-20

A method for separating carbohydrates from pulping liquors includes the steps of providing a wood pulping or wood or biomass hydrolysis pulping liquor having lignin therein, and mixing the liquor with an acid or a gas which forms an acid upon contact with water to initiate precipitation of carbohydrate to begin formation of a precipitate. During precipitation, at least one long chain carboxylated carbohydrate and at least one cationic polymer, such as a polyamine or polyimine are added, wherein the precipitate aggregates into larger precipitate structures. Carbohydrate gel precipitates are then selectively removed from the larger precipitate structures. The method process yields both a carbohydrate precipitate and a high purity lignin.

Precipitation Estimate Using NEXRAD Ground-Based Radar Images: Validation, Calibration and Spatial Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xuesong

2012-12-17

Precipitation is an important input variable for hydrologic and ecological modeling and analysis. Next Generation Radar (NEXRAD) can provide precipitation products that cover most of the continental United States with a high resolution display of approximately 4 × 4 km2. Two major issues concerning the applications of NEXRAD data are (1) lack of a NEXRAD geo-processing and geo-referencing program and (2) bias correction of NEXRAD estimates. In this chapter, a geographic information system (GIS) based software that can automatically support processing of NEXRAD data for hydrologic and ecological models is presented. Some geostatistical approaches to calibrating NEXRAD data using rainmore » gauge data are introduced, and two case studies on evaluating accuracy of NEXRAD Multisensor Precipitation Estimator (MPE) and calibrating MPE with rain-gauge data are presented. The first case study examines the performance of MPE in mountainous region versus south plains and cold season versus warm season, as well as the effect of sub-grid variability and temporal scale on NEXRAD performance. From the results of the first case study, performance of MPE was found to be influenced by complex terrain, frozen precipitation, sub-grid variability, and temporal scale. Overall, the assessment of MPE indicates the importance of removing bias of the MPE precipitation product before its application, especially in the complex mountainous region. The second case study examines the performance of three MPE calibration methods using rain gauge observations in the Little River Experimental Watershed in Georgia. The comparison results show that no one method can perform better than the others in terms of all evaluation coefficients and for all time steps. For practical estimation of precipitation distribution, implementation of multiple methods to predict spatial precipitation is suggested.« less

A modified method for determining tannin-protein precipitation capacity using accelerated solvent extraction (ASE) and microplate gel filtration.

PubMed

McArt, Scott H; Spalinger, Donald E; Kennish, John M; Collins, William B

2006-06-01

The protein precipitation assay used by Robbins et al., (1987) Ecology 68:98-107 has been shown to predict successfully the reduction in protein availability to some ruminants due to tannins. The procedure, however, is expensive and laborious, which limits its utility, especially for quantitative ecological or nutritional applications where large numbers of assays may be required. We have modified the method to decrease its cost and increase laboratory efficiency by: (1) automating the extraction by using Accelerated Solvent Extraction (ASE); and (2) by scaling and automating the precipitation reaction, chromatography, and spectrometry with microplate gel filtration and an automated UV-VIS microplate spectrometer. ASE extraction is shown to be as effective at extracting tannins as the hot methanol technique. Additionally, the microplate assay is sensitive and precise. We show that the results from the new technique correspond in a nearly 1:1 relationship to the results of the previous technique. Hence, this method could reliably replace the older method with no loss in relevance to herbivore protein digestion. Moreover, the ASE extraction technique should be applicable to other tannin-protein precipitation assays and possibly other phenolic assays.

Size fractionation of double-stranded DNA by precipitation with polyethylene glycol

PubMed Central

Lis, John T.; Schleif, Robert

1975-01-01

We show that DNA molecules of differing molecular mass are separable by selective precipitation with polyethylene glycol (PEG†). Higher molecular mass DNA precipitates at lower PEG concentrations than lower molecular mass DNA. Double-stranded DNA can be fractionated at least in the range of 3 × 107 to 1 × 105 daltons. The effects of PEG concentration, sodium chloride concentration, DNA concentration, pH, divalent ions, precipitation time, and centrifugal force have been determined. These studies show PEG precipitation offers a size fractionation method for DNA which is convenient, of high capacity, and applicable over a wide range of conditions. However, resolution is not high and separation of two species approaches 100% only if they differ in molecular mass by at least a factor of two. Images PMID:236548

BASIC PEROXIDE PRECIPITATION METHOD OF SEPARATING PLUTONIUM FROM CONTAMINANTS

DOEpatents

Seaborg, G.T.; Perlman, I.

1959-02-10

A process is described for the separation from each other of uranyl values, tetravalent plutonium values and fission products contained in an aqueous acidic solution. First the pH of the solution is adjusted to between 2.5 and 8 and hydrogen peroxide is then added to the solution causing precipitation of uranium peroxide which carries any plutonium values present, while the fission products remain in solution. Separation of the uranium and plutonium values is then effected by dissolving the peroxide precipitate in an acidic solution and incorporating a second carrier precipitate, selective for plutonium. The plutonium values are thus carried from the solution while the uranium remains flissolved. The second carrier precipitate may be selected from among the group consisting of rare earth fluorides, and oxalates, zirconium phosphate, and bismuth lihosphate.

Evaluation of global climate model on performances of precipitation simulation and prediction in the Huaihe River basin

NASA Astrophysics Data System (ADS)

Wu, Yenan; Zhong, Ping-an; Xu, Bin; Zhu, Feilin; Fu, Jisi

2017-06-01

Using climate models with high performance to predict the future climate changes can increase the reliability of results. In this paper, six kinds of global climate models that selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under Representative Concentration Path (RCP) 4.5 scenarios were compared to the measured data during baseline period (1960-2000) and evaluate the simulation performance on precipitation. Since the results of single climate models are often biased and highly uncertain, we examine the back propagation (BP) neural network and arithmetic mean method in assembling the precipitation of multi models. The delta method was used to calibrate the result of single model and multimodel ensembles by arithmetic mean method (MME-AM) during the validation period (2001-2010) and the predicting period (2011-2100). We then use the single models and multimodel ensembles to predict the future precipitation process and spatial distribution. The result shows that BNU-ESM model has the highest simulation effect among all the single models. The multimodel assembled by BP neural network (MME-BP) has a good simulation performance on the annual average precipitation process and the deterministic coefficient during the validation period is 0.814. The simulation capability on spatial distribution of precipitation is: calibrated MME-AM > MME-BP > calibrated BNU-ESM. The future precipitation predicted by all models tends to increase as the time period increases. The order of average increase amplitude of each season is: winter > spring > summer > autumn. These findings can provide useful information for decision makers to make climate-related disaster mitigation plans.

Geophysical methods for monitoring soil stabilization processes

NASA Astrophysics Data System (ADS)

Saneiyan, Sina; Ntarlagiannis, Dimitrios; Werkema, D. Dale; Ustra, Andréa

2018-01-01

Soil stabilization involves methods used to turn unconsolidated and unstable soil into a stiffer, consolidated medium that could support engineered structures, alter permeability, change subsurface flow, or immobilize contamination through mineral precipitation. Among the variety of available methods carbonate precipitation is a very promising one, especially when it is being induced through common soil borne microbes (MICP - microbial induced carbonate precipitation). Such microbial mediated precipitation has the added benefit of not harming the environment as other methods can be environmentally detrimental. Carbonate precipitation, typically in the form of calcite, is a naturally occurring process that can be manipulated to deliver the expected soil strengthening results or permeability changes. This study investigates the ability of spectral induced polarization and shear-wave velocity for monitoring calcite driven soil strengthening processes. The results support the use of these geophysical methods as soil strengthening characterization and long term monitoring tools, which is a requirement for viable soil stabilization projects. Both tested methods are sensitive to calcite precipitation, with SIP offering additional information related to long term stability of precipitated carbonate. Carbonate precipitation has been confirmed with direct methods, such as direct sampling and scanning electron microscopy (SEM). This study advances our understanding of soil strengthening processes and permeability alterations, and is a crucial step for the use of geophysical methods as monitoring tools in microbial induced soil alterations through carbonate precipitation.

A new moisture tagging capability in the Weather Research and Forecasting model: formulation, validation and application to the 2014 Great Lake-effect snowstorm

NASA Astrophysics Data System (ADS)

Insua-Costa, Damián; Miguez-Macho, Gonzalo

2018-02-01

A new moisture tagging tool, usually known as water vapor tracer (WVT) method or online Eulerian method, has been implemented into the Weather Research and Forecasting (WRF) regional meteorological model, enabling it for precise studies on atmospheric moisture sources and pathways. We present here the method and its formulation, along with details of the implementation into WRF. We perform an in-depth validation with a 1-month long simulation over North America at 20 km resolution, tagging all possible moisture sources: lateral boundaries, continental, maritime or lake surfaces and initial atmospheric conditions. We estimate errors as the moisture or precipitation amounts that cannot be traced back to any source. Validation results indicate that the method exhibits high precision, with errors considerably lower than 1 % during the entire simulation period, for both precipitation and total precipitable water. We apply the method to the Great Lake-effect snowstorm of November 2014, aiming at quantifying the contribution of lake evaporation to the large snow accumulations observed in the event. We perform simulations in a nested domain at 5 km resolution with the tagging technique, demonstrating that about 30-50 % of precipitation in the regions immediately downwind, originated from evaporated moisture in the Great Lakes. This contribution increases to between 50 and 60 % of the snow water equivalent in the most severely affected areas, which suggests that evaporative fluxes from the lakes have a fundamental role in producing the most extreme accumulations in these episodes, resulting in the highest socioeconomic impacts.

Resolving the morphology of niobium carbonitride nano-precipitates in steel using atom probe tomography.

PubMed

Breen, Andrew J; Xie, Kelvin Y; Moody, Michael P; Gault, Baptiste; Yen, Hung-Wei; Wong, Christopher C; Cairney, Julie M; Ringer, Simon P

2014-08-01

Atom probe is a powerful technique for studying the composition of nano-precipitates, but their morphology within the reconstructed data is distorted due to the so-called local magnification effect. A new technique has been developed to mitigate this limitation by characterizing the distribution of the surrounding matrix atoms, rather than those contained within the nano-precipitates themselves. A comprehensive chemical analysis enables further information on size and chemistry to be obtained. The method enables new insight into the morphology and chemistry of niobium carbonitride nano-precipitates within ferrite for a series of Nb-microalloyed ultra-thin cast strip steels. The results are supported by complementary high-resolution transmission electron microscopy.

Interpolating precipitation and its relation to runoff and non-point source pollution.

PubMed

Chang, Chia-Ling; Lo, Shang-Lien; Yu, Shaw-L

2005-01-01

When rainfall spatially varies, complete rainfall data for each region with different rainfall characteristics are very important. Numerous interpolation methods have been developed for estimating unknown spatial characteristics. However, no interpolation method is suitable for all circumstances. In this study, several methods, including the arithmetic average method, the Thiessen Polygons method, the traditional inverse distance method, and the modified inverse distance method, were used to interpolate precipitation. The modified inverse distance method considers not only horizontal distances but also differences between the elevations of the region with no rainfall records and of its surrounding rainfall stations. The results show that when the spatial variation of rainfall is strong, choosing a suitable interpolation method is very important. If the rainfall is uniform, the precipitation estimated using any interpolation method would be quite close to the actual precipitation. When rainfall is heavy in locations with high elevation, the rainfall changes with the elevation. In this situation, the modified inverse distance method is much more effective than any other method discussed herein for estimating the rainfall input for WinVAST to estimate runoff and non-point source pollution (NPSP). When the spatial variation of rainfall is random, regardless of the interpolation method used to yield rainfall input, the estimation errors of runoff and NPSP are large. Moreover, the relationship between the relative error of the predicted runoff and predicted pollutant loading of SS is high. However, the pollutant concentration is affected by both runoff and pollutant export, so the relationship between the relative error of the predicted runoff and the predicted pollutant concentration of SS may be unstable.

Comparing bias correction methods in downscaling meteorological variables for a hydrologic impact study in an arid area in China

NASA Astrophysics Data System (ADS)

Fang, G. H.; Yang, J.; Chen, Y. N.; Zammit, C.

2015-06-01

Water resources are essential to the ecosystem and social economy in the desert and oasis of the arid Tarim River basin, northwestern China, and expected to be vulnerable to climate change. It has been demonstrated that regional climate models (RCMs) provide more reliable results for a regional impact study of climate change (e.g., on water resources) than general circulation models (GCMs). However, due to their considerable bias it is still necessary to apply bias correction before they are used for water resources research. In this paper, after a sensitivity analysis on input meteorological variables based on the Sobol' method, we compared five precipitation correction methods and three temperature correction methods in downscaling RCM simulations applied over the Kaidu River basin, one of the headwaters of the Tarim River basin. Precipitation correction methods applied include linear scaling (LS), local intensity scaling (LOCI), power transformation (PT), distribution mapping (DM) and quantile mapping (QM), while temperature correction methods are LS, variance scaling (VARI) and DM. The corrected precipitation and temperature were compared to the observed meteorological data, prior to being used as meteorological inputs of a distributed hydrologic model to study their impacts on streamflow. The results show (1) streamflows are sensitive to precipitation, temperature and solar radiation but not to relative humidity and wind speed; (2) raw RCM simulations are heavily biased from observed meteorological data, and its use for streamflow simulations results in large biases from observed streamflow, and all bias correction methods effectively improved these simulations; (3) for precipitation, PT and QM methods performed equally best in correcting the frequency-based indices (e.g., standard deviation, percentile values) while the LOCI method performed best in terms of the time-series-based indices (e.g., Nash-Sutcliffe coefficient, R2); (4) for temperature, all correction methods performed equally well in correcting raw temperature; and (5) for simulated streamflow, precipitation correction methods have more significant influence than temperature correction methods and the performances of streamflow simulations are consistent with those of corrected precipitation; i.e., the PT and QM methods performed equally best in correcting flow duration curve and peak flow while the LOCI method performed best in terms of the time-series-based indices. The case study is for an arid area in China based on a specific RCM and hydrologic model, but the methodology and some results can be applied to other areas and models.

A comparative verification of high resolution precipitation forecasts using model output statistics

NASA Astrophysics Data System (ADS)

van der Plas, Emiel; Schmeits, Maurice; Hooijman, Nicolien; Kok, Kees

2017-04-01

Verification of localized events such as precipitation has become even more challenging with the advent of high-resolution meso-scale numerical weather prediction (NWP). The realism of a forecast suggests that it should compare well against precipitation radar imagery with similar resolution, both spatially and temporally. Spatial verification methods solve some of the representativity issues that point verification gives rise to. In this study a verification strategy based on model output statistics is applied that aims to address both double penalty and resolution effects that are inherent to comparisons of NWP models with different resolutions. Using predictors based on spatial precipitation patterns around a set of stations, an extended logistic regression (ELR) equation is deduced, leading to a probability forecast distribution of precipitation for each NWP model, analysis and lead time. The ELR equations are derived for predictands based on areal calibrated radar precipitation and SYNOP observations. The aim is to extract maximum information from a series of precipitation forecasts, like a trained forecaster would. The method is applied to the non-hydrostatic model Harmonie (2.5 km resolution), Hirlam (11 km resolution) and the ECMWF model (16 km resolution), overall yielding similar Brier skill scores for the 3 post-processed models, but larger differences for individual lead times. Besides, the Fractions Skill Score is computed using the 3 deterministic forecasts, showing somewhat better skill for the Harmonie model. In other words, despite the realism of Harmonie precipitation forecasts, they only perform similarly or somewhat better than precipitation forecasts from the 2 lower resolution models, at least in the Netherlands.

Evaporation, precipitation, and associated salinity changes at a humid, subtropical estuary

USGS Publications Warehouse

Sumner, D.M.; Belaineh, G.

2005-01-01

The distilling effect of evaporation and the diluting effect of precipitation on salinity at two estuarine sites in the humid subtropical setting of the Indian River Lagoon, Florida, were evaluated based on daily evaporation computed with an energy-budget method and measured precipitation. Despite the larger magnitude of evaporation (about 1,580 mm yr-1) compared to precipitation (about 1,180 mm yr-1) between February 2002 and January 2004, the variability of monthly precipitation induced salinity changes was more than twice the variability of evaporation induced changes. Use of a constant, mean value of evaporation, along with measured values of daily precipitation, were sufficient to produce simulated salinity changes that contained little monthly (root-mean-square error = 0.33??? mo-1 and 0.52??? mo-1 at the two sites) or cumulative error (<1??? yr-1) compared to simulations that used computed daily values of evaporation. This result indicates that measuring the temporal variability in evaporation may not be critical to simulation of salinity within the lagoon. Comparison of evaporation and precipitation induced salinity changes with measured salinity changes indicates that evaporation and precipitation explained only 4% of the changes in salinity within a flow-through area of the lagoon; surface water and ocean inflows probably accounted for most of the variability in salinity at this site. Evaporation and precipitation induced salinity changes explained 61% of the variability in salinity at a flow-restricted part of the lagoon. ?? 2005 Estuarine Research Federation.

The Use of Convolutional Neural Network in Relating Precipitation to Circulation

NASA Astrophysics Data System (ADS)

Pan, B.; Hsu, K. L.; AghaKouchak, A.; Sorooshian, S.

2017-12-01

Precipitation prediction in dynamical weather and climate models depends on 1) the predictability of pressure or geopotential height for the forecasting period and 2) the successive work of interpreting the pressure field in terms of precipitation events. The later task is represented as parameterization schemes in numerical models, where detailed computing inevitably blurs the hidden cause-and-effect relationship in precipitation generation. The "big data" provided by numerical simulation, reanalysis and observation networks requires better causation analysis for people to digest and realize their use. While classic synoptical analysis methods are very-often insufficient for spatially distributed high dimensional data, a Convolutional Neural Network(CNN) is developed here to directly relate precipitation with circulation. Case study carried over west coast United States during boreal winter showed that CNN can locate and capture key pressure zones of different structures to project precipitation spatial distribution with high accuracy across hourly to monthly scales. This direct connection between atmospheric circulation and precipitation offers a probe for attributing precipitation to the coverage, location, intensity and spatial structure of characteristic pressure zones, which can be used for model diagnosis and improvement.

Uncertainty in determining extreme precipitation thresholds

NASA Astrophysics Data System (ADS)

Liu, Bingjun; Chen, Junfan; Chen, Xiaohong; Lian, Yanqing; Wu, Lili

2013-10-01

Extreme precipitation events are rare and occur mostly on a relatively small and local scale, which makes it difficult to set the thresholds for extreme precipitations in a large basin. Based on the long term daily precipitation data from 62 observation stations in the Pearl River Basin, this study has assessed the applicability of the non-parametric, parametric, and the detrended fluctuation analysis (DFA) methods in determining extreme precipitation threshold (EPT) and the certainty to EPTs from each method. Analyses from this study show the non-parametric absolute critical value method is easy to use, but unable to reflect the difference of spatial rainfall distribution. The non-parametric percentile method can account for the spatial distribution feature of precipitation, but the problem with this method is that the threshold value is sensitive to the size of rainfall data series and is subjected to the selection of a percentile thus make it difficult to determine reasonable threshold values for a large basin. The parametric method can provide the most apt description of extreme precipitations by fitting extreme precipitation distributions with probability distribution functions; however, selections of probability distribution functions, the goodness-of-fit tests, and the size of the rainfall data series can greatly affect the fitting accuracy. In contrast to the non-parametric and the parametric methods which are unable to provide information for EPTs with certainty, the DFA method although involving complicated computational processes has proven to be the most appropriate method that is able to provide a unique set of EPTs for a large basin with uneven spatio-temporal precipitation distribution. The consistency between the spatial distribution of DFA-based thresholds with the annual average precipitation, the coefficient of variation (CV), and the coefficient of skewness (CS) for the daily precipitation further proves that EPTs determined by the DFA method are more reasonable and applicable for the Pearl River Basin.

Satellite and Model Analysis of the Atmospheric Moisture Budget in High Latitudes: High Resolution Precipitation Over Greenland Studied from Dynamic Method

NASA Technical Reports Server (NTRS)

Bromwich, David H.; Chen, Qiu-shi

2002-01-01

Observations of precipitation over Greenland are limited. Direct precipitation measurements for the whole ice sheet are impractical, and those in the coastal region have substantial uncertainty but may be correctable with some effort. However, the analyzed wind, geopotential height and moisture fields are available for recent years, and the precipitation is retrievable from these fields by a dynamic method. Based on recent Greenland precipitation from dynamic studies, several deficiencies in the precipitation spatial distributions from these dynamic methods were evaluated by Bromwich et al.

Regional analysis of annual precipitation maxima in Montana

USGS Publications Warehouse

Parrett, Charles

1997-01-01

Dimensionless precipitation-frequency curves for estimating precipitation depths having large recurrence intervals were developed for 2-, 6-, and 24-hour storm durations for three homogeneous regions in Montana. Within each homogeneous region, at-site annual precipitation maxima were made dimensionless by dividing by the at-site mean and grouped so that a single frequency curve would be applicable for each duration. L-moment statistics were used to help define the homogeneous regions and to develop the dimensionless precipitation- frequency curves. Data from 459 precipitation stations were used after application of statistical tests to ensure that the data were not serially correlated and were stationary over the general period of data collection (1900-92). The data were found to have a small, but significant, degree of interstation correlation. The GEV distribution was used to construct dimensionless frequency curves of annual precipitation maxima for each duration within each region. Each dimensionless frequency curve was considered to be reliable for recurrence intervals up to the effective record length. Because of significant, though small, interstation correlation in all regions for all durations, and because the selected regions exhibited some heterogeneity, the effective record length was considered to be less than the total number of station-years of data. The effective record length for each duration in each region was estimated using a graphical method and found to range from 500 years for 6-hour duration data in Region 2 to 5,100 years for 24-hour duration data in Region 3.

Infrared thermography of evaporative fluxes and dynamics of salt deposition on heterogeneous porous surfaces

NASA Astrophysics Data System (ADS)

Nachshon, Uri; Shahraeeni, Ebrahim; Or, Dani; Dragila, Maria; Weisbrod, Noam

2011-12-01

Evaporation of saline solutions from porous media, common in arid areas, involves complex interactions between mass transport, energy exchange and phase transitions. We quantified evaporation of saline solutions from heterogeneous sand columns under constant hydraulic boundary conditions to focus on effects of salt precipitation on evaporation dynamics. Mass loss measurements and infrared thermography were used to quantify evaporation rates. The latter method enables quantification of spatial and temporal variability of salt precipitation to identify its dynamic effects on evaporation. Evaporation from columns filled with texturally-contrasting sand using different salt solutions revealed preferential salt precipitation within the fine textured domains. Salt precipitation reduced evaporation rates from the fine textured regions by nearly an order of magnitude. In contrast, low evaporation rates from coarse-textured regions (due to low capillary drive) exhibited less salt precipitation and consequently less evaporation rate suppression. Experiments provided insights into two new phenomena: (1) a distinct increase in evaporation rate at the onset of evaporation; and (2) a vapor pumping mechanism related to the presence of a salt crust over semidry media. Both phenomena are related to local vapor pressure gradients established between pore water and the surface salt crust. Comparison of two salts: NaCl and NaI, which tend to precipitate above the matrix surface and within matrix pores, respectively, shows a much stronger influence of NaCl on evaporation rate suppression. This disparity reflects the limited effect of NaI precipitation on matrix resistivity for solution and vapor flows.

A novel isolation method for hen egg yolk antibody, "IgY".

PubMed

Hatta, H; Kim, M; Yamamoto, T

1990-10-01

A method for isolation of egg yolk immunoglobulin, IgG, a livetin protein, was investigated. Several natural gums (carrageenan and xanthan gum) were found to be effective for removal of yolk lipoprotein as a precipitate. The effect was pronounced with lambda-carrageenan and the lipid content in the supernatant after removal of the resulting precipitate was less than 0.4% of that of egg yolk. IgY remained in this supernatant, with a yield of 86%, and was isolated by chromatography on a column of DEAE-Sephacel followed by salting-out with sodium sulfate. IgY thus isolated was almost pure (98%) and the yield was 70 to 100 mg per egg.

Assessment of Areal Recharge to the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

USGS Publications Warehouse

Bartolino, James R.

2007-01-01

A numerical flow model of the Spokane Valley-Rathdrum Prairie aquifer currently (2007) being developed requires the input of values for areally-distributed recharge, a parameter that is often the most uncertain component of water budgets and ground-water flow models because it is virtually impossible to measure over large areas. Data from six active weather stations in and near the study area were used in four recharge-calculation techniques or approaches; the Langbein method, in which recharge is estimated on the basis of empirical data from other basins; a method developed by the U.S. Department of Agriculture (USDA), in which crop consumptive use and effective precipitation are first calculated and then subtracted from actual precipitation to yield an estimate of recharge; an approach developed as part of the Eastern Snake Plain Aquifer Model (ESPAM) Enhancement Project in which recharge is calculated on the basis of precipitation-recharge relations from other basins; and an approach in which reference evapotranspiration is calculated by the Food and Agriculture Organization (FAO) Penman-Monteith equation, crop consumptive use is determined (using a single or dual coefficient approach), and recharge is calculated. Annual recharge calculated by the Langbein method for the six weather stations was 4 percent of annual mean precipitation, yielding the lowest values of the methods discussed in this report, however, the Langbein method can be only applied to annual time periods. Mean monthly recharge calculated by the USDA method ranged from 53 to 73 percent of mean monthly precipitation. Mean annual recharge ranged from 64 to 69 percent of mean annual precipitation. Separate mean monthly recharge calculations were made with the ESPAM method using initial input parameters to represent thin-soil, thick-soil, and lava-rock conditions. The lava-rock parameters yielded the highest recharge values and the thick-soil parameters the lowest. For thin-soil parameters, calculated monthly recharge ranged from 10 to 29 percent of mean monthly precipitation and annual recharge ranged from 16 to 23 percent of mean annual precipitation. For thick-soil parameters, calculated monthly recharge ranged from 1 to 5 percent of mean monthly precipitation and mean annual recharge ranged from 2 to 4 percent of mean annual precipitation. For lava-rock parameters, calculated mean monthly recharge ranged from 37 to 57 percent of mean monthly precipitation and mean annual recharge ranged from 45 to 52 percent of mean annual precipitation. Single-coefficient (crop coefficient) FAO Penman-Monteith mean monthly recharge values were calculated for Spokane Weather Service Office (WSO) Airport, the only station for which the necessary meteorological data were available. Grass-referenced values of mean monthly recharge ranged from 0 to 81 percent of mean monthly precipitation and mean annual recharge was 21 percent of mean annual precipitation; alfalfa-referenced values of mean monthly recharge ranged from 0 to 85 percent of mean monthly precipitation and mean annual recharge was 24 percent of mean annual precipitation. Single-coefficient FAO Penman-Monteith calculations yielded a mean monthly recharge of zero during the eight warmest and driest months of the year (March-October). In order to refine the mean monthly recharge estimates, dual-coefficient (basal crop and soil evaporation coefficients) FAO Penman-Monteith dual-crop evapotranspiration and deep-percolation calculations were applied to daily values from the Spokane WSO Airport for January 1990 through December 2005. The resultant monthly totals display a temporal variability that is absent from the mean monthly values and demonstrate that the daily amount and timing of precipitation dramatically affect calculated recharge. The dual-coefficient FAO Penman-Monteith calculations were made for the remaining five stations using wind-speed values for Spokane WSO Airport and other assumptions regarding

High-resolution near real-time drought monitoring in South Asia

NASA Astrophysics Data System (ADS)

Aadhar, Saran; Mishra, Vimal

2017-10-01

Drought in South Asia affect food and water security and pose challenges for millions of people. For policy-making, planning, and management of water resources at sub-basin or administrative levels, high-resolution datasets of precipitation and air temperature are required in near-real time. We develop a high-resolution (0.05°) bias-corrected precipitation and temperature data that can be used to monitor near real-time drought conditions over South Asia. Moreover, the dataset can be used to monitor climatic extremes (heat and cold waves, dry and wet anomalies) in South Asia. A distribution mapping method was applied to correct bias in precipitation and air temperature, which performed well compared to the other bias correction method based on linear scaling. Bias-corrected precipitation and temperature data were used to estimate Standardized precipitation index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) to assess the historical and current drought conditions in South Asia. We evaluated drought severity and extent against the satellite-based Normalized Difference Vegetation Index (NDVI) anomalies and satellite-driven Drought Severity Index (DSI) at 0.05°. The bias-corrected high-resolution data can effectively capture observed drought conditions as shown by the satellite-based drought estimates. High resolution near real-time dataset can provide valuable information for decision-making at district and sub-basin levels.

Relative Humidity Has Uneven Effects on Shifts From Snow to Rain Over the Western U.S.

NASA Astrophysics Data System (ADS)

Harpold, A. A.; Rajagopal, S.; Crews, J. B.; Winchell, T.; Schumer, R.

2017-10-01

Predicting the phase of precipitation is fundamental to water supply and hazard forecasting. Phase prediction methods (PPMs) are used to predict snow fraction, or the ratio of snowfall to total precipitation. Common temperature-based regression (Dai method) and threshold at freezing (0°C) PPMs had comparable accuracy to a humidity-based PPM (TRH method) using 6 and 24 h observations. Using a daily climate data set from 1980 to 2015, the TRH method estimates 14% and 6% greater precipitation-weighted snow fraction than the 0°C and Dai methods, respectively. The TRH method predicts four times less area with declining snow fraction than the Dai method (2.1% and 8.1% of the study domain, respectively) from 1980 to 2015, with the largest differences in the Cascade and Sierra Nevada mountains and southwestern U.S. Future Representative Concentration Pathway (RCP) 8.5 projections suggest warming temperatures of 4.2°C and declining relative humidity of 1% over the 21st century. The TRH method predicts a smaller reduction in snow fraction than temperature-only PPMs by 2100, consistent with lower humidity buffering declines in snow fraction caused by regional warming.

Formulation and characterization of fisetin nanosuspension

NASA Astrophysics Data System (ADS)

Dzakwan, M.; Pramukantoro, G. E.; Mauludin, R.; Wikarsa, S.

2017-11-01

Fisetin (3,3,4,7-tetrahydroxyflavone) is a natural antioxidant that has shown to posses anticancer, antioxidant and anti-inflammatory properties. However, the poor solubility leads to poor bioavailability and limits its development. The aim of the study is to investigate the effect of fisetin nanosuspension using a precipitation-sonication method and additional stabilizers polysorbat 80, SLS, F68, PVP, PVA and HPMC on particle size average and the polydispersity index. The suspensions of microcrystalline FIS were prepared by a precipitation method with different proportion of stabilizers fixed. The nanosuspension produced was then characterized using Photon Correlation Spectroscopy (PCS) in term of particle size distribution, polydispersity index and morphology particle (SEM). Result showed fisetin nanosuspension were successfully prepared by anti-solvent precipitation with additional stabilizer SLS and PVA. The nanosuspension containing PVA showed smaller average particle size of 406 nm, a polydispersity index of 0.22±0.1 was obtained. The drug particles precipitated with the PVA as stabilizer were spherical in shape.

Evaluation of three methods for the concentration of poliovirus from oysters.

PubMed

Bouchriti, N; Goyal, S M

1992-10-01

Three methods for the concentration of poliovirus from oyster homogenates were compared. The adsorption-elution-precipitation method gave the lowest average virus recovery (24.1%), while the beef extract elution-acid precipitation method and the non-fat dry milk elution-acid precipitation methods gave recoveries of 47.2% and 39.6%, respectively. Although the overall recovery rates with these methods were lower than those reported in previous studies, recoveries of 40-47% obtained with the elution-precipitation methods used in the present study are considered to be above average in terms of recovery efficiency.

Simultaneous Precipitation of Solar Protons and Relativistic Electrons as a New Factor Affecting the Earth's Atmosphere

NASA Astrophysics Data System (ADS)

Shirochkov, A. V.; Sokolov, S. N.

In the field of solar - terrestrial physics during the last decade there has been renewed interest in the effects produced in the Earth atmosphere and ionosphere by fluxes of precipitated highly relativistic electrons. A series of investigation on the subject (preferably by means of satellite measurements) was performed recently, which discussed different aspects of these phenomena called HRE events. More careful study of the HRE events revealed previously unnoticed geophysical phenomenon: a great majority of the solar proton events (SPE) were accompanied by simultaneous precipitation of relativistic electron fluxes. The studies of previous SPE events attributed their atmospheric and ionospheric effects entirely to the solar proton fluxes. It turned out that such an assumption is wrong. Therefore we have actually a new class of geophysical phenomena when the Earth's atmosphere and ionosphere experience combined impact of simultaneously precipitating fluxes of solar protons and relativistic electrons. If one takes into accounts effect of enhanced density of the solar wind during the SPEs (i.e. its dynamic pressure) the real situation during these combined events became more complicated. In this paper the effects during the storm of May 1992 are analyzed as an example of such unusual combination. The methods of separation of the effects produced by different precipitation particles are presented. Other similar events are considered to demonstrate that such complex events are not unique geophysical phenomena.

The effect of multiple stressors on salt marsh end-of-season biomass

USGS Publications Warehouse

Visser, J.M.; Sasser, C.E.; Cade, B.S.

2006-01-01

It is becoming more apparent that commonly used statistical methods (e.g., analysis of variance and regression) are not the best methods for estimating limiting relationships or stressor effects. A major challenge of estimating the effects associated with a measured subset of limiting factors is to account for the effects of unmeasured factors in an ecologically realistic matter. We used quantile regression to elucidate multiple stressor effects on end-of-season biomass data from two salt marsh sites in coastal Louisiana collected for 18 yr. Stressor effects evaluated based on available data were flooding, salinity, air temperature, cloud cover, precipitation deficit, grazing by muskrat, and surface water nitrogen and phosphorus. Precipitation deficit combined with surface water nitrogen provided the best two-parameter model to explain variation in the peak biomass with different slopes and intercepts for the two study sites. Precipitation deficit, cloud cover, and temperature were significantly correlated with each other. Surface water nitrogen was significantly correlated with surface water phosphorus and muskrat density. The site with the larger duration of flooding showed reduced peak biomass, when cloud cover and surface water nitrogen were optimal. Variation in the relatively low salinity occurring in our study area did not explain any of the variation in Spartina alterniflora biomass. ?? 2006 Estuarine Research Federation.

The effect of multiple stressors on salt marsh end-of-season biomass

USGS Publications Warehouse

Visser, J.M.; Sasser, C.E.; Cade, B.S.

2006-01-01

It is becoming more apparent that commonly used statistical methods (e.g. analysis of variance and regression) are not the best methods for estimating limiting relationships or stressor effects. A major challenge of estimating the effects associated with a measured subset of limiting factors is to account for the effects of unmeasured factors in an ecologically realistic matter. We used quantile regression to elucidate multiple stressor effects on end-of-season biomass data from two salt marsh sites in coastal Louisiana collected for 18 yr. Stressor effects evaluated based on available data were flooding, salinity air temperature, cloud cover, precipitation deficit, grazing by muskrat, and surface water nitrogen and phosphorus. Precipitation deficit combined with surface water nitrogen provided the best two-parameter model to explain variation in the peak biomass with different slopes and intercepts for the two study sites. Precipitation deficit, cloud cover, and temperature were significantly correlated with each other. Surface water nitrogen was significantly correlated with surface water phosphorus and muskrat density. The site with the larger duration of flooding showed reduced peak biomass, when cloud cover and surface water nitrogen were optimal. Variation in the relatively low salinity occurring in our study area did not explain any of the variation in Spartina alterniflora biomass.

An in situ USAXS-SAXS-WAXS study of precipitate size distribution evolution in a model Ni-based alloy.

PubMed

Andrews, Ross N; Serio, Joseph; Muralidharan, Govindarajan; Ilavsky, Jan

2017-06-01

Intermetallic γ' precipitates typically strengthen nickel-based superalloys. The shape, size and spatial distribution of strengthening precipitates critically influence alloy strength, while their temporal evolution characteristics determine the high-temperature alloy stability. Combined ultra-small-, small- and wide-angle X-ray scattering (USAXS-SAXS-WAXS) analysis can be used to evaluate the temporal evolution of an alloy's precipitate size distribution (PSD) and phase structure during in situ heat treatment. Analysis of PSDs from USAXS-SAXS data employs either least-squares fitting of a preordained PSD model or a maximum entropy (MaxEnt) approach, the latter avoiding a priori definition of a functional form of the PSD. However, strong low- q scattering from grain boundaries and/or structure factor effects inhibit MaxEnt analysis of typical alloys. This work describes the extension of Bayesian-MaxEnt analysis methods to data exhibiting structure factor effects and low- q power law slopes and demonstrates their use in an in situ study of precipitate size evolution during heat treatment of a model Ni-Al-Si alloy.

An in situ USAXS–SAXS–WAXS study of precipitate size distribution evolution in a model Ni-based alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrews, Ross N.; Serio, Joseph A.; Muralidharan, Govindarajan

Intermetallic γ' precipitates typically strengthen nickel-based superalloys. The shape, size and spatial distribution of strengthening precipitates critically influence alloy strength, while their temporal evolution characteristics determine the high-temperature alloy stability. Combined ultra-small-, small- and wide-angle X-ray scattering (USAXS–SAXS–WAXS) analysis can be used to evaluate the temporal evolution of an alloy's precipitate size distribution (PSD) and phase structure duringin situheat treatment. Analysis of PSDs from USAXS–SAXS data employs either least-squares fitting of a preordained PSD model or a maximum entropy (MaxEnt) approach, the latter avoidinga prioridefinition of a functional form of the PSD. However, strong low-qscattering from grain boundaries and/or structuremore » factor effects inhibit MaxEnt analysis of typical alloys. Lastly, this work describes the extension of Bayesian–MaxEnt analysis methods to data exhibiting structure factor effects and low-qpower law slopes and demonstrates their use in anin situstudy of precipitate size evolution during heat treatment of a model Ni–Al–Si alloy.« less

An in situ USAXS–SAXS–WAXS study of precipitate size distribution evolution in a model Ni-based alloy1

PubMed Central

Andrews, Ross N.; Serio, Joseph; Muralidharan, Govindarajan; Ilavsky, Jan

2017-01-01

Intermetallic γ′ precipitates typically strengthen nickel-based superalloys. The shape, size and spatial distribution of strengthening precipitates critically influence alloy strength, while their temporal evolution characteristics determine the high-temperature alloy stability. Combined ultra-small-, small- and wide-angle X-ray scattering (USAXS–SAXS–WAXS) analysis can be used to evaluate the temporal evolution of an alloy’s precipitate size distribution (PSD) and phase structure during in situ heat treatment. Analysis of PSDs from USAXS–SAXS data employs either least-squares fitting of a preordained PSD model or a maximum entropy (MaxEnt) approach, the latter avoiding a priori definition of a functional form of the PSD. However, strong low-q scattering from grain boundaries and/or structure factor effects inhibit MaxEnt analysis of typical alloys. This work describes the extension of Bayesian–MaxEnt analysis methods to data exhibiting structure factor effects and low-q power law slopes and demonstrates their use in an in situ study of precipitate size evolution during heat treatment of a model Ni–Al–Si alloy. PMID:28656039

3D DDD modelling of dislocation-precipitate interaction in a nickel-based single crystal superalloy under cyclic deformation

NASA Astrophysics Data System (ADS)

Lin, Bing; Huang, Minsheng; Zhao, Liguo; Roy, Anish; Silberschmidt, Vadim; Barnard, Nick; Whittaker, Mark; McColvin, Gordon

2018-06-01

Strain-controlled cyclic deformation of a nickel-based single crystal superalloy has been modelled using three-dimensional (3D) discrete dislocation dynamics (DDD) for both [0 0 1] and [1 1 1] orientations. The work focused on the interaction between dislocations and precipitates during cyclic plastic deformation at elevated temperature, which has not been well studied yet. A representative volume element with cubic γ‧-precipitates was chosen to represent the material, with enforced periodical boundary conditions. In particular, cutting of superdislocations into precipitates was simulated by a back-force method. The global cyclic stress-strain responses were captured well by the DDD model when compared to experimental data, particularly the effects of crystallographic orientation. Dislocation evolution showed that considerably high density of dislocations was produced for [1 1 1] orientation when compared to [0 0 1] orientation. Cutting of dislocations into the precipitates had a significant effect on the plastic deformation, leading to material softening. Contour plots of in-plane shear strain proved the development of heterogeneous strain field, resulting in the formation of shear-band embryos.

An in situ USAXS–SAXS–WAXS study of precipitate size distribution evolution in a model Ni-based alloy

DOE PAGES

Andrews, Ross N.; Serio, Joseph A.; Muralidharan, Govindarajan; ...

2017-05-30

Intermetallic γ' precipitates typically strengthen nickel-based superalloys. The shape, size and spatial distribution of strengthening precipitates critically influence alloy strength, while their temporal evolution characteristics determine the high-temperature alloy stability. Combined ultra-small-, small- and wide-angle X-ray scattering (USAXS–SAXS–WAXS) analysis can be used to evaluate the temporal evolution of an alloy's precipitate size distribution (PSD) and phase structure duringin situheat treatment. Analysis of PSDs from USAXS–SAXS data employs either least-squares fitting of a preordained PSD model or a maximum entropy (MaxEnt) approach, the latter avoidinga prioridefinition of a functional form of the PSD. However, strong low-qscattering from grain boundaries and/or structuremore » factor effects inhibit MaxEnt analysis of typical alloys. Lastly, this work describes the extension of Bayesian–MaxEnt analysis methods to data exhibiting structure factor effects and low-qpower law slopes and demonstrates their use in anin situstudy of precipitate size evolution during heat treatment of a model Ni–Al–Si alloy.« less

RAPID METHOD FOR DETERMINATION OF RADIOSTRONTIUM IN EMERGENCY MILK SAMPLES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, S.; Culligan, B.

2008-07-17

A new rapid separation method for radiostrontium in emergency milk samples was developed at the Savannah River Site (SRS) Environmental Bioassay Laboratory (Aiken, SC, USA) that will allow rapid separation and measurement of Sr-90 within 8 hours. The new method uses calcium phosphate precipitation, nitric acid dissolution of the precipitate to coagulate residual fat/proteins and a rapid strontium separation using Sr Resin (Eichrom Technologies, Darien, IL, USA) with vacuum-assisted flow rates. The method is much faster than previous method that use calcination or cation exchange pretreatment, has excellent chemical recovery, and effectively removes beta interferences. When a 100 ml samplemore » aliquot is used, the method has a detection limit of 0.5 Bq/L, well below generic emergency action levels.« less

Mid-Western US heavy summer-precipitation in regional and global climate models: the impact on model skill and consensus through an analogue lens

NASA Astrophysics Data System (ADS)

Gao, Xiang; Schlosser, C. Adam

2018-04-01

Regional climate models (RCMs) can simulate heavy precipitation more accurately than general circulation models (GCMs) through more realistic representation of topography and mesoscale processes. Analogue methods of downscaling, which identify the large-scale atmospheric conditions associated with heavy precipitation, can also produce more accurate and precise heavy precipitation frequency in GCMs than the simulated precipitation. In this study, we examine the performances of the analogue method versus direct simulation, when applied to RCM and GCM simulations, in detecting present-day and future changes in summer (JJA) heavy precipitation over the Midwestern United States. We find analogue methods are comparable to MERRA-2 and its bias-corrected precipitation in characterizing the occurrence and interannual variations of observed heavy precipitation events, all significantly improving upon MERRA precipitation. For the late twentieth-century heavy precipitation frequency, RCM precipitation improves upon the corresponding driving GCM with greater accuracy yet comparable inter-model discrepancies, while both RCM- and GCM-based analogue results outperform their model-simulated precipitation counterparts in terms of accuracy and model consensus. For the projected trends in heavy precipitation frequency through the mid twenty-first century, analogue method also manifests its superiority to direct simulation with reduced intermodel disparities, while the RCM-based analogue and simulated precipitation do not demonstrate a salient improvement (in model consensus) over the GCM-based assessment. However, a number of caveats preclude any overall judgement, and further work—over any region of interest—should include a larger sample of GCMs and RCMs as well as ensemble simulations to comprehensively account for internal variability.

Method of precipitating uranium from an aqueous solution and/or sediment

DOEpatents

Tokunaga, Tetsu K; Kim, Yongman; Wan, Jiamin

2013-08-20

A method for precipitating uranium from an aqueous solution and/or sediment comprising uranium and/or vanadium is presented. The method includes precipitating uranium as a uranyl vanadate through mixing an aqueous solution and/or sediment comprising uranium and/or vanadium and a solution comprising a monovalent or divalent cation to form the corresponding cation uranyl vanadate precipitate. The method also provides a pathway for extraction of uranium and vanadium from an aqueous solution and/or sediment.

Calcite phase determination of CaCO3 nanoparticles synthesized by one step drying method

NASA Astrophysics Data System (ADS)

Sulimai, N. H.; Rani, Rozina Abdul; Khusaimi, Z.; Abdullah, S.; Salifairus, M. J.; Alrokayan, Salman; Khan, Haseeb; Rusop, M.

2018-05-01

Calcium Carbonate (CaCO3) is a type of carbonic salt. It exist naturally as white odourless solid and may also be synthesized by chemical reactions. This work studies one-step precipitation of CaCO3 that was prepared by novel method of one-step precipitation method. The method was then proceeded by different types of drying. The first type is by normal drying in oven whereas the second type is with the presence of hydrothermal influence. From the results, precipitated CaCO3 dried by normal drying method produces CaCO3 with two polymorphs present; calcite and vaterite. Normal drying at 500°C has no vaterite phase left. Drying by hydrothermal precipitated CaCO3 has Nitrogen (N) left on the surfaces of the precipitated CaCO3. This work successfully identified calcite phase in the precipitated CaCO3.

Matrix precipitation: a general strategy to eliminate matrix interference for pharmaceutical toxic impurities analysis.

PubMed

Yang, Xiaojing; Xiong, Xuewu; Cao, Ji; Luan, Baolei; Liu, Yongjun; Liu, Guozhu; Zhang, Lei

2015-01-30

Matrix interference, which can lead to false positive/negative results, contamination of injector or separation column, incompatibility between sample solution and the selected analytical instrument, and response inhibition or even quenching, is commonly suffered for the analysis of trace level toxic impurities in drug substance. In this study, a simple matrix precipitation strategy is proposed to eliminate or minimize the above stated matrix interference problems. Generally, a sample of active pharmaceutical ingredients (APIs) is dissolved in an appropriate solvent to achieve the desired high concentration and then an anti-solvent is added to precipitate the matrix substance. As a result, the target analyte is extracted into the mixed solution with very less residual of APIs. This strategy has the characteristics of simple manipulation, high recovery and excellent anti-interference capability. It was found that the precipitation ratio (R, representing the ability to remove matrix substance) and the proportion of solvent (the one used to dissolve APIs) in final solution (P, affecting R and also affecting the method sensitivity) are two important factors of the precipitation process. The correlation between R and P was investigated by performing precipitation with various APIs in different solvent/anti-solvent systems. After a detailed mathematical reasoning process, P=20% was proved to be an effective and robust condition to perform the precipitation strategy. The precipitation method with P=20% can be used as a general strategy for toxic impurity analysis in APIs. Finally, several typical examples are described in this article, where the challenging matrix interference issues have been resolved successfully. Copyright © 2014 Elsevier B.V. All rights reserved.

AI-based (ANN and SVM) statistical downscaling methods for precipitation estimation under climate change scenarios

NASA Astrophysics Data System (ADS)

Mehrvand, Masoud; Baghanam, Aida Hosseini; Razzaghzadeh, Zahra; Nourani, Vahid

2017-04-01

Since statistical downscaling methods are the most largely used models to study hydrologic impact studies under climate change scenarios, nonlinear regression models known as Artificial Intelligence (AI)-based models such as Artificial Neural Network (ANN) and Support Vector Machine (SVM) have been used to spatially downscale the precipitation outputs of Global Climate Models (GCMs). The study has been carried out using GCM and station data over GCM grid points located around the Peace-Tampa Bay watershed weather stations. Before downscaling with AI-based model, correlation coefficient values have been computed between a few selected large-scale predictor variables and local scale predictands to select the most effective predictors. The selected predictors are then assessed considering grid location for the site in question. In order to increase AI-based downscaling model accuracy pre-processing has been developed on precipitation time series. In this way, the precipitation data derived from various GCM data analyzed thoroughly to find the highest value of correlation coefficient between GCM-based historical data and station precipitation data. Both GCM and station precipitation time series have been assessed by comparing mean and variances over specific intervals. Results indicated that there is similar trend between GCM and station precipitation data; however station data has non-stationary time series while GCM data does not. Finally AI-based downscaling model have been applied to several GCMs with selected predictors by targeting local precipitation time series as predictand. The consequences of recent step have been used to produce multiple ensembles of downscaled AI-based models.

Effect of modification methods on the surface properties and n-butane isomerization performance of La/Ni-promoted SO42-/ZrO2-Al2O3

NASA Astrophysics Data System (ADS)

Wang, Pengzhao; Zhang, Jiaoyu; Han, Chaoyi; Yang, Chaohe; Li, Chunyi

2016-08-01

The La and/or Ni was introduced into alumina-promoted sulfated zirconia by impregnation and co-precipitation to improve the catalytic property of n-butane isomerization. Catalysts characterization shows that the addition of La/Ni has a remarkable influence on the surface and textual properties depending on the modification method. The impregnation of La/Ni facilitates the transformation of a small amount of tetragonal zirconia into monoclinic phase, while the co-precipitation improves the stability of tetragonal ZrO2. H2-TPR indicates that the addition of La/Ni changes the interaction between SO42- and supports, which affects the acidity on the surface. Specifically, the Lewis acidity is significantly enhanced by either modification method. The co-precipitation reserves almost all of the Brønsted acid sites, while the impregnation causes a remarkable decrease of Brønsted acid sites. Reaction results demonstrate that the co-precipitation exhibits a significant advantage over impregnation that the higher conversion of n-butane and selectivity to isobutane are obtained on the catalyst prepared by co-precipitation. The increase of catalytic activity is ascribed to the accelerated activation rate of n-butane molecules by hydride subtraction on the Lewis acid sites at higher reaction temperature. Furthermore, the addition of La/Ni improves the selectivity to isobutane by inhibiting the bimolecular reaction.

a Study of Precipitation Using Dual-Frequency and Interferometric Doppler Radars.

NASA Astrophysics Data System (ADS)

Chilson, Phillip Bruce

The primary focus of this dissertation involves the investigation of precipitation using Doppler radar but using distinctly different methods. Each method will be treated separately. The first part describes an investigation of a tropical thunderstorm that occurred in the summer of 1991 over the National Astronomy and Ionosphere Center in Arecibo, Puerto Rico. Observations were made using a vertically pointing, dual-wavelength, collinear beam Doppler radar which permits virtually simultaneous observations of the same pulse volume using transmission and reception of coherent UHF and VHF signals on alternate pulses. This made it possible to measure directly the vertical wind within the sampling volume using the VHF signal while using the UHF signal to study the nature of the precipitation. The observed storm showed strong similarities with systems observed in the Global Atmospheric Research Program's (GARP) Atlantic Tropical Experiment (GATE) study. The experiment provided a means of determining various parameters associated with the storm, such as the vertical air velocity, the mean fall speeds of the precipitation, and the reflectivity. Rogers proposed a means of deducing the mean fall speed of precipitation particles using the radar reflectivity factor. Using the data from our experiment, the mean precipitation fall speeds were calculated and compared with those that would be inferred from Rogers' method. The results suggest the Rogers method of estimating mean precipitation fall speeds to be unreliable in turbulent environments. The second part reports observations made with the 50 MHz Middle and Upper Atmosphere (MU) radar located at Shigaraki, Japan during May of 1992. The facility was operated in a spatial interferometry (SI) mode while observing frontal precipitation. The data suggest that the presence of precipitation can produce a bias in the SI cross-spectral phase that in turn creates an overestimation of the horizontal wind. The process is likened to turbulent fading which produces a temporal decorrelation in the time history of the complex radar voltages. In the case of precipitation, it is proposed that the size distribution of the hydrometeors produces a similar effect. This work examines the supposition by creating mathematical and computer simulations to test for any biases introduced by an exponential form of the drop-size distribution. The simulations were run for both the cases of Bragg scatter from turbulent variations in the refractive index and Rayleigh scatter from precipitation particles. Finally the simulation results were compared with actual radar data. It is shown that particle size distributions do indeed influence the cross -spectral phase which in turn leads to erroneous horizontal wind estimates.

Temporal and spatial characteristics of extreme precipitation events in the Midwest of Jilin Province based on multifractal detrended fluctuation analysis method and copula functions

NASA Astrophysics Data System (ADS)

Guo, Enliang; Zhang, Jiquan; Si, Ha; Dong, Zhenhua; Cao, Tiehua; Lan, Wu

2017-10-01

Environmental changes have brought about significant changes and challenges to water resources and management in the world; these include increasing climate variability, land use change, intensive agriculture, and rapid urbanization and industrial development, especially much more frequency extreme precipitation events. All of which greatly affect water resource and the development of social economy. In this study, we take extreme precipitation events in the Midwest of Jilin Province as an example; daily precipitation data during 1960-2014 are used. The threshold of extreme precipitation events is defined by multifractal detrended fluctuation analysis (MF-DFA) method. Extreme precipitation (EP), extreme precipitation ratio (EPR), and intensity of extreme precipitation (EPI) are selected as the extreme precipitation indicators, and then the Kolmogorov-Smirnov (K-S) test is employed to determine the optimal probability distribution function of extreme precipitation indicators. On this basis, copulas connect nonparametric estimation method and the Akaike Information Criterion (AIC) method is adopted to determine the bivariate copula function. Finally, we analyze the characteristics of single variable extremum and bivariate joint probability distribution of the extreme precipitation events. The results show that the threshold of extreme precipitation events in semi-arid areas is far less than that in subhumid areas. The extreme precipitation frequency shows a significant decline while the extreme precipitation intensity shows a trend of growth; there are significant differences in spatiotemporal of extreme precipitation events. The spatial variation trend of the joint return period gets shorter from the west to the east. The spatial distribution of co-occurrence return period takes on contrary changes and it is longer than the joint return period.

Effects of isoconcentration surface threshold values on the characteristics of needle-shaped precipitates in atom probe tomography data from an aged Al-Mg-Si alloy.

PubMed

Aruga, Yasuhiro; Kozuka, Masaya

2016-04-01

Needle-shaped precipitates in an aged Al-0.62Mg-0.93Si (mass%) alloy were identified using a compositional threshold method, an isoconcentration surface, in atom probe tomography (APT). The influence of thresholds on the morphological and compositional characteristics of the precipitates was investigated. Utilizing optimum parameters for the concentration space, a reliable number density of the precipitates is obtained without dependence on the elemental concentration threshold in comparison with evaluation by transmission electron microscopy (TEM). It is suggested that careful selection of the concentration space in APT can lead to a reasonable average Mg/Si ratio for the precipitates. It was found that the maximum length and maximum diameter of the precipitates are affected by the elemental concentration threshold. Adjustment of the concentration threshold gives better agreement with the precipitate dimensions measured by TEM. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Projected Response of Low-Level Convergence and Associated Precipitation to Greenhouse Warming

NASA Astrophysics Data System (ADS)

Weller, Evan; Jakob, Christian; Reeder, Michael J.

2017-10-01

The parameterization of convection in climate models is a large source of uncertainty in projecting future precipitation changes. Here an objective method to identify organized low-level convergence lines has been used to better understand how atmospheric convection is organized and projected to change, as low-level convergence plays an important role in the processes leading to precipitation. The frequency and strength of convergence lines over both ocean and land in current climate simulations is too low compared to reanalysis data. Projections show a further reduction in the frequency and strength of convergence lines over the midlatitudes. In the tropics, the largest changes in frequency are generally associated with shifts in major low-latitude convergence zones, consistent with changes in the precipitation. Further, examining convergence lines when in the presence or absence of precipitation results in large spatial contrasts, providing a better understanding of regional changes in terms of thermodynamic and dynamic effects.

Microwave (SSM/I) Estimates of the Precipitation Rate to Improve Numerical Atmospheric Model Forecasts

NASA Technical Reports Server (NTRS)

Raymond, William H.; Olson, William S.

1990-01-01

Delay in the spin-up of precipitation early in numerical atmospheric forecasts is a deficiency correctable by diabatic initialization combined with diabatic forcing. For either to be effective requires some knowledge of the magnitude and vertical placement of the latent heating fields. Until recently the best source of cloud and rain water data was the remotely sensed vertical integrated precipitation rate or liquid water content. Vertical placement of the condensation remains unknown. Some information about the vertical distribution of the heating rates and precipitating liquid water and ice can be obtained from retrieval techniques that use a physical model of precipitating clouds to refine and improve the interpretation of the remotely sensed data. A description of this procedure and an examination of its 3-D liquid water products, along with improved modeling methods that enhance or speed-up storm development is discussed.

Solvent shift method for anti-precipitant screening of poorly soluble drugs using biorelevant medium and dimethyl sulfoxide.

PubMed

Yamashita, Taro; Ozaki, Shunsuke; Kushida, Ikuo

2011-10-31

96-well plate based anti-precipitant screening using bio-relevant medium FaSSIF (fasted-state simulated small intestinal fluid) is a useful technique for discovering anti-precipitants that maintain supersaturation of poorly soluble drugs. In a previous report, two disadvantages of the solvent evaporation method (solvent casting method) were mentioned: precipitation during the evaporation process and the use of volatile solvents to dissolve compounds. In this report, we propose a solvent shift method using DMSO (dimethyl sulfoxide). Initially, the drug substance was dissolved in DMSO at a high concentration and diluted with FaSSIF that contained anti-precipitants. To evaluate the validity of the method, itraconazole (ITZ) was used as the poorly soluble model drug. The solvent shift method resolved the disadvantages of the evaporation method, and AQOAT (HPMC-AS) was found as the most appropriate anti-precipitant for ITZ in a facile and expeditious manner when compared with the solvent evaporation method. In the large scale JP paddle method, AQOAT-based solid dispersion maintained a higher concentration than Tc-5Ew (HPMC)-based formulation; this result corresponded well with the small scale of the solvent shift method. Copyright © 2011 Elsevier B.V. All rights reserved.

Kriging and local polynomial methods for blending satellite-derived and gauge precipitation estimates to support hydrologic early warning systems

USGS Publications Warehouse

Verdin, Andrew; Funk, Christopher C.; Rajagopalan, Balaji; Kleiber, William

2016-01-01

Robust estimates of precipitation in space and time are important for efficient natural resource management and for mitigating natural hazards. This is particularly true in regions with developing infrastructure and regions that are frequently exposed to extreme events. Gauge observations of rainfall are sparse but capture the precipitation process with high fidelity. Due to its high resolution and complete spatial coverage, satellite-derived rainfall data are an attractive alternative in data-sparse regions and are often used to support hydrometeorological early warning systems. Satellite-derived precipitation data, however, tend to underrepresent extreme precipitation events. Thus, it is often desirable to blend spatially extensive satellite-derived rainfall estimates with high-fidelity rain gauge observations to obtain more accurate precipitation estimates. In this research, we use two different methods, namely, ordinary kriging and κ-nearest neighbor local polynomials, to blend rain gauge observations with the Climate Hazards Group Infrared Precipitation satellite-derived precipitation estimates in data-sparse Central America and Colombia. The utility of these methods in producing blended precipitation estimates at pentadal (five-day) and monthly time scales is demonstrated. We find that these blending methods significantly improve the satellite-derived estimates and are competitive in their ability to capture extreme precipitation.

[Estimating the impacts of future climate change on water requirement and water deficit of winter wheat in Henan Province, China].

PubMed

Ji, Xing-jie; Cheng, Lin; Fang, Wen-song

2015-09-01

Based on the analysis of water requirement and water deficit during development stage of winter wheat in recent 30 years (1981-2010) in Henan Province, the effective precipitation was calculated using the U.S. Department of Agriculture Soil Conservation method, the water requirement (ETC) was estimated by using FAO Penman-Monteith equation and crop coefficient method recommended by FAO, combined with the climate change scenario A2 (concentration on the economic envelopment) and B2 ( concentration on the sustainable development) of Special Report on Emissions Scenarios (SRES) , the spatial and temporal characteristics of impacts of future climate change on effective precipitation, water requirement and water deficit of winter wheat were estimated. The climatic impact factors of ETc and WD also were analyzed. The results showed that under A2 and B2 scenarios, there would be a significant increase in anomaly percentage of effective precipitation, water requirement and water deficit of winter wheat during the whole growing period compared with the average value from 1981 to 2010. Effective precipitation increased the most in 2030s under A2 and B2 scenarios by 33.5% and 39.2%, respectively. Water requirement increased the most in 2010s under A2 and B2 scenarios by 22.5% and 17.5%, respectively, and showed a significant downward trend with time. Water deficit increased the most under A2 scenario in 2010s by 23.6% and under B2 scenario in 2020s by 13.0%. Partial correlation analysis indicated that solar radiation was the main cause for the variation of ETc and WD in future under A2 and B2 scenarios. The spatial distributions of effective precipitation, water requirement and water deficit of winter wheat during the whole growing period were spatially heterogeneous because of the difference in geographical and climatic environments. A possible tendency of water resource deficiency may exist in Henan Province in the future.

Effects of 4D-Var data assimilation using remote sensing precipitation products in a WRF over the complex Heihe River Basin

NASA Astrophysics Data System (ADS)

Pan, Xiaoduo; Li, Xin; Cheng, Guodong

2017-04-01

Traditionally, ground-based, in situ observations, remote sensing, and regional climate modeling, individually, cannot provide the high-quality precipitation data required for hydrological prediction, especially over complex terrain. Data assimilation techniques are often used to assimilate ground observations and remote sensing products into models for dynamic downscaling. In this study, the Weather Research and Forecasting (WRF) model was used to assimilate two satellite precipitation products (TRMM 3B42 and FY-2D) using the 4D-Var data assimilation method. The results show that the assimilation of remote sensing precipitation products can improve the initial WRF fields of humidity and temperature, thereby improving precipitation forecasting and decreasing the spin-up time. Hence, assimilating TRMM and FY-2D remote sensing precipitation products using WRF 4D-Var can be viewed as a positive step toward improving the accuracy and lead time of numerical weather prediction models, particularly for short-term weather forecasting. Future work is proposed to assimilate a suite of remote sensing data, e.g., the combination of precipitation and soil moisture data, into a WRF model to improve 7-8 day forecasts of precipitation and other atmospheric variables.

Drought severity in intensive agricultural areas by means of the EDI index

NASA Astrophysics Data System (ADS)

Procházková, Petra; Chuchma, Filip; Středa, Tomáš

2016-12-01

The aim of this work was the evaluation of drought severity development in the Czech Republic for the period 1971-2015 by the means of the Effective Drought Index (EDI). Annual values of the EDI index were determined using the method of effective precipitation for 14 localities spread throughout the Czech Republic (Central Europe). The seven categories were created according to obtained index values for the drought conditions determination for years during the period 1971-2015 through the percentile method. The annual index values were compared with acquired 2nd, 15th, 45th, 55th, 85th and 98th percentiles. Both the years with precipitation unfavourable conditions: 1972, 1973, 1984, 1990, 1991, 1992, 1993 and 2015 and the years with precipitation favourable conditions: 1977, 1987, 1995, 2001, 2002 and 2010 were determined. Precipitation conditions in the growing season from 61st to 180th day of the year were also analysed. This evaluation was conducted during the period 1971-2015 through the ten-day index values which were compared with acquired 2nd, 15th, 45th, 55th, 85th and 98th percentiles. Dry growing seasons occurred in 1973, 1974, 1976 and 1993. Wet growing seasons occurred in 1987, 2006 and 2010. Trend analysis of annual index values was performed through the Mann-Kendall test. Highly statistically significant increasing linear trends (P < 0.01) were found for four localities (Uherský Ostroh, Vysoká, Znojmo-Oblekovice and Žatec); statistically significant increasing trends (P < 0.05) were found for three localities (Brno-Chrlice, Lednice and Lípa). Based on the extrapolation of the trend, a slightly higher effective precipitation can be expected during the year in a substantial part of the country. However, these findings do not necessarily mean an optimal supply of agricultural land with water. Precipitation exhibits considerable unevenness of distribution through time. Given the increasing evapotranspiration demands of the environment their availability is limited.

Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

PubMed

Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

2016-04-01

Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+.

Logit-normal mixed model for Indian monsoon precipitation

NASA Astrophysics Data System (ADS)

Dietz, L. R.; Chatterjee, S.

2014-09-01

Describing the nature and variability of Indian monsoon precipitation is a topic of much debate in the current literature. We suggest the use of a generalized linear mixed model (GLMM), specifically, the logit-normal mixed model, to describe the underlying structure of this complex climatic event. Four GLMM algorithms are described and simulations are performed to vet these algorithms before applying them to the Indian precipitation data. The logit-normal model was applied to light, moderate, and extreme rainfall. Findings indicated that physical constructs were preserved by the models, and random effects were significant in many cases. We also found GLMM estimation methods were sensitive to tuning parameters and assumptions and therefore, recommend use of multiple methods in applications. This work provides a novel use of GLMM and promotes its addition to the gamut of tools for analysis in studying climate phenomena.

PROCESS FOR THE SEPARATION OF HEAVY METALS

DOEpatents

Gofman, J.W.; Connick, R.E.; Wahl, A.C.

1959-01-27

A method is presented for thc separation of plutonium from uranium and the fission products with which it is associated. The method is based on the fact that hexavalent plutonium forms an insoluble complex precipitate with sodium acetate, as does the uranyl ion, while reduced plutonium is not precipitated by sodium acetate. Several embodiments are shown, e.g., a solution containing plutonium and uranium in the hexavalent state may be contacted with sodium acetate causing the formation of a sodium uranyl acetate precipitate which carries the plutonium values while the fission products remain in solution. If the original solution is treated with a reducing agent, so that the plutonium is reduced while the uranium remains in the hexavalent state, and sodium and acetate ions are added, the uranium will precipitutc while the plutonium remains in solution effecting separation of the Pu from urarium.

Effect of Co on Discontinuous Precipitation Transformation with TCP Phase in Ni-based Alloy Containing Re

NASA Astrophysics Data System (ADS)

Shi, Qianying; An, Ning; Huo, Jiajie; Zheng, Yunrong; Feng, Qiang

2017-05-01

The effect of Co on discontinuous precipitation (DP) transformation involving the formation of topologically close-packed (TCP) phase was investigated in three Ni-Cr-Re model alloys containing different levels of Co. One typical TCP phase, σ, was generated within DP cellular colonies along the migrating grain boundaries in experimental alloys during aging treatment. As a result of the increased solubility of Re in the γ matrix and enlarged interlamellar spacing of σ precipitates inside of growing DP colonies, Co addition suppressed the formation of σ phase and associated DP colonies. This study suggests that Co could potentially serve as a microstructural stabilizer in Re-containing Ni-base superalloys, which provides an alternative method for the composition optimization of superalloys.

Enhanced precipitation promotes decomposition and soil C stabilization in semiarid ecosystems, but seasonal timing of wetting matters

USGS Publications Warehouse

Campos, Xochi; Germino, Matthew; de Graaff, Marie-Anne

2017-01-01

AimsChanging precipitation regimes in semiarid ecosystems will affect the balance of soil carbon (C) input and release, but the net effect on soil C storage is unclear. We asked how changes in the amount and timing of precipitation affect litter decomposition, and soil C stabilization in semiarid ecosystems.MethodsThe study took place at a long-term (18 years) ecohydrology experiment located in Idaho. Precipitation treatments consisted of a doubling of annual precipitation (+200 mm) added either in the cold-dormant season or in the growing season. Experimental plots were planted with big sagebrush (Artemisia tridentata), or with crested wheatgrass (Agropyron cristatum). We quantified decomposition of sagebrush leaf litter, and we assessed organic soil C (SOC) in aggregates, and silt and clay fractions.ResultsWe found that: (1) increased precipitation applied in the growing season consistently enhanced decomposition rates relative to the ambient treatment, and (2) precipitation applied in the dormant season enhanced soil C stabilization.ConclusionsThese data indicate that prolonged increases in precipitation can promote soil C storage in semiarid ecosystems, but only if these increases happen at times of the year when conditions allow for precipitation to promote plant C inputs rates to soil.

High-Resolution Near Real-Time Drought Monitoring in South Asia

NASA Astrophysics Data System (ADS)

Aadhar, S.; Mishra, V.

2017-12-01

Drought in South Asia affect food and water security and pose challenges for millions of people. For policy-making, planning and management of water resources at the sub-basin or administrative levels, high-resolution datasets of precipitation and air temperature are required in near-real time. Here we develop a high resolution (0.05 degree) bias-corrected precipitation and temperature data that can be used to monitor near real-time drought conditions over South Asia. Moreover, the dataset can be used to monitor climatic extremes (heat waves, cold waves, dry and wet anomalies) in South Asia. A distribution mapping method was applied to correct bias in precipitation and air temperature (maximum and minimum), which performed well compared to the other bias correction method based on linear scaling. Bias-corrected precipitation and temperature data were used to estimate Standardized precipitation index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) to assess the historical and current drought conditions in South Asia. We evaluated drought severity and extent against the satellite-based Normalized Difference Vegetation Index (NDVI) anomalies and satellite-driven Drought Severity Index (DSI) at 0.05˚. We find that the bias-corrected high-resolution data can effectively capture observed drought conditions as shown by the satellite-based drought estimates. High resolution near real-time dataset can provide valuable information for decision-making at district and sub- basin levels.

How does bias correction of RCM precipitation affect modelled runoff?

NASA Astrophysics Data System (ADS)

Teng, J.; Potter, N. J.; Chiew, F. H. S.; Zhang, L.; Vaze, J.; Evans, J. P.

2014-09-01

Many studies bias correct daily precipitation from climate models to match the observed precipitation statistics, and the bias corrected data are then used for various modelling applications. This paper presents a review of recent methods used to bias correct precipitation from regional climate models (RCMs). The paper then assesses four bias correction methods applied to the weather research and forecasting (WRF) model simulated precipitation, and the follow-on impact on modelled runoff for eight catchments in southeast Australia. Overall, the best results are produced by either quantile mapping or a newly proposed two-state gamma distribution mapping method. However, the difference between the tested methods is small in the modelling experiments here (and as reported in the literature), mainly because of the substantial corrections required and inconsistent errors over time (non-stationarity). The errors remaining in bias corrected precipitation are typically amplified in modelled runoff. The tested methods cannot overcome limitation of RCM in simulating precipitation sequence, which affects runoff generation. Results further show that whereas bias correction does not seem to alter change signals in precipitation means, it can introduce additional uncertainty to change signals in high precipitation amounts and, consequently, in runoff. Future climate change impact studies need to take this into account when deciding whether to use raw or bias corrected RCM results. Nevertheless, RCMs will continue to improve and will become increasingly useful for hydrological applications as the bias in RCM simulations reduces.

Cadmium, copper, lead, and zinc determination in precipitation: A comparison of inductively coupled plasma atomic emission spectrometry and graphite furnace atomization atomic absorption spectrometry

USGS Publications Warehouse

Reddy, M.M.; Benefiel, M.A.; Claassen, H.C.

1987-01-01

Selected trace element analysis for cadmium, copper, lead, and zinc in precipitation samples by inductively coupled plasma atomic emission Spectrometry (ICP) and by atomic absorption spectrometry with graphite furnace atomization (AAGF) have been evaluated. This task was conducted in conjunction with a longterm study of precipitation chemistry at high altitude sites located in remote areas of the southwestern United States. Coefficients of variation and recovery values were determined for a standard reference water sample for all metals examined for both techniques. At concentration levels less than 10 micrograms per liter AAGF analyses exhibited better precision and accuracy than ICP. Both methods appear to offer the potential for cost-effective analysis of trace metal ions in precipitation. ?? 1987 Springer-Verlag.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szcześ, Aleksandra, E-mail: aszczes@poczta.umcs.lublin.pl; Czemierska, Magdalena; Jarosz-Wilkołazka, Anna

Extracellular polymeric substance (EPS) extracted from Rhodococcus opacus bacterial strain was used as a matrix for calcium carbonate precipitation using the vapour diffusion method. The total exopolymer and water-soluble exopolymer fraction of different concentrations were spread on the mica surface by the spin-coating method. The obtained layers were characterized using the atomic force microscopy measurement and XPS analysis. The effects of polymer concentration, initial pH of calcium chloride solution and precipitation time on the obtained crystals properties were investigated. Raman spectroscopy and scanning electron microscopy were used to characterize the precipitated minerals. It was found that the type of precipitatedmore » CaCO{sub 3} polymorph and the crystal size depend on the kind of EPS fraction. The obtained results indicates that the water soluble fraction favours vaterite dissolution and calcite growth, whereas the total EPS stabilizes vaterite and this effect is stronger at basic pH. It seems to be due to different contents of the functional group of EPS fractions. - Highlights: • CaCO{sub 3} crystal size and polymorph can be controlled by EPS substance obtained from R. opacus. • The water soluble fraction favours vaterite dissolution and calcite growth. • The total EPS stabilizes vaterite. • This effect is stronger at basic pH.« less

A non-chromatographic method for the removal of endotoxins from bacteriophages.

PubMed

Branston, Steven D; Wright, Jason; Keshavarz-Moore, Eli

2015-08-01

The Ff filamentous bacteriophages show potential as a new class of therapeutics, displaying utility in materials science as well as pharmaceutical applications. These phages are produced by the infection of E. coli, a Gram-negative bacterium which unavoidably sheds endotoxins into the extracellular space during growth. Since endotoxin molecules are highly immunoreactive, separation from the phage product is of critical importance, particularly those developed for human therapeutic use. The properties of M13, one of the Ff group, present a purification challenge chiefly because the standard scalable method for endotoxin removal from proteins-anion exchange chromatography-is not applicable due to pI similarity between the particles. This article examines the potential of polyethylene glycol (PEG)-NaCl precipitation as a scalable method for the separation of endotoxins from phage M13. Precipitation of M13 by 2% (w/v) PEG 6 000, 500 mM NaCl reduced endotoxin contamination of the phage product by 88%, but additional precipitation rounds did not maintain this proportional decrease. Dynamic light scattering was subsequently used to determine the effectiveness of a detergent to disassociate endotoxin molecules from M13. As a result, PEG-NaCl precipitation was supplemented with up to 2% (v/v) Triton X-100 to improve separation. A 5.7 log10 reduction in endotoxin concentration was achieved over three rounds of precipitation whilst retaining over 97% of the phage. This method compares favorably with the well-known ATPS (Triton X-114) technique for endotoxin removal from protein solutions. © 2015 Wiley Periodicals, Inc.

Effect of Synthesis Method of La1 - x Sr x MnO3 Manganite Nanoparticles on Their Properties

NASA Astrophysics Data System (ADS)

Shlapa, Yulia; Solopan, Sergii; Belous, Anatolii; Tovstolytkin, Alexandr

2018-01-01

Nanoparticles of lanthanum-strontium manganite were synthesized via different methods, namely, sol-gel method, precipitation from non-aqueous solution, and precipitation from reversal microemulsions. It was shown that the use of organic compounds and non-aqueous media allowed significantly decreasing of the crystallization temperature of nanoparticles, and the single-phased crystalline product was formed in one stage. Morphology and properties of nanoparticles depended on the method and conditions of the synthesis. The heating efficiency directly depended on the change in the magnetic parameters of nanoparticles, especially on the magnetization. Performed studies showed that each of these methods of synthesis can be used to obtain weakly agglomerated manganite nanoparticles; however, particles synthesized via sol-gel method are more promising for use as hyperthermia inducers. PACS: 61.46.Df 75.75.Cd 81.20. Fw

A rapid method for the sequential separation of polonium, plutonium, americium and uranium in drinking water.

PubMed

Lemons, B; Khaing, H; Ward, A; Thakur, P

2018-06-01

A new sequential separation method for the determination of polonium and actinides (Pu, Am and U) in drinking water samples has been developed that can be used for emergency response or routine water analyses. For the first time, the application of TEVA chromatography column in the sequential separation of polonium and plutonium has been studied. This method utilizes a rapid Fe +3 co-precipitation step to remove matrix interferences, followed by plutonium oxidation state adjustment to Pu 4+ and an incubation period of ~ 1 h at 50-60 °C to allow Po 2+ to oxidize to Po 4+ . The polonium and plutonium were then separated on a TEVA column, while separation of americium from uranium was performed on a TRU column. After separation, polonium was micro-precipitated with copper sulfide (CuS), while actinides were micro co-precipitated using neodymium fluoride (NdF 3 ) for counting by the alpha spectrometry. The method is simple, robust and can be performed quickly with excellent removal of interferences, high chemical recovery and very good alpha peak resolution. The efficiency and reliability of the procedures were tested by using spiked samples. The effect of several transition metals (Cu 2+ , Pb 2+ , Fe 3+ , Fe 2+ , and Ni 2+ ) on the performance of this method were also assessed to evaluate the potential matrix effects. Studies indicate that presence of up to 25 mg of these cations in the samples had no adverse effect on the recovery or the resolution of polonium alpha peaks. Copyright © 2018 Elsevier Ltd. All rights reserved.

Particle-Size-Grouping Model of Precipitation Kinetics in Microalloyed Steels

NASA Astrophysics Data System (ADS)

Xu, Kun; Thomas, Brian G.

2012-03-01

The formation, growth, and size distribution of precipitates greatly affects the microstructure and properties of microalloyed steels. Computational particle-size-grouping (PSG) kinetic models based on population balances are developed to simulate precipitate particle growth resulting from collision and diffusion mechanisms. First, the generalized PSG method for collision is explained clearly and verified. Then, a new PSG method is proposed to model diffusion-controlled precipitate nucleation, growth, and coarsening with complete mass conservation and no fitting parameters. Compared with the original population-balance models, this PSG method saves significant computation and preserves enough accuracy to model a realistic range of particle sizes. Finally, the new PSG method is combined with an equilibrium phase fraction model for plain carbon steels and is applied to simulate the precipitated fraction of aluminum nitride and the size distribution of niobium carbide during isothermal aging processes. Good matches are found with experimental measurements, suggesting that the new PSG method offers a promising framework for the future development of realistic models of precipitation.

Evaporation from weighing precipitation gauges: impacts on automated gauge measurements and quality assurance methods

NASA Astrophysics Data System (ADS)

Leeper, R. D.; Kochendorfer, J.

2015-06-01

Evaporation from a precipitation gauge can cause errors in the amount of measured precipitation. For automated weighing-bucket gauges, the World Meteorological Organization (WMO) suggests the use of evaporative suppressants and frequent observations to limit these biases. However, the use of evaporation suppressants is not always feasible due to environmental hazards and the added cost of maintenance, transport, and disposal of the gauge additive. In addition, research has suggested that evaporation prior to precipitation may affect precipitation measurements from auto-recording gauges operating at sub-hourly frequencies. For further evaluation, a field campaign was conducted to monitor evaporation and its impacts on the quality of precipitation measurements from gauges used at U.S. Climate Reference Network (USCRN) stations. Two Geonor gauges were collocated, with one gauge using an evaporative suppressant (referred to as Geonor-NonEvap) and the other with no suppressant (referred to as Geonor-Evap) to evaluate evaporative losses and evaporation biases on precipitation measurements. From June to August, evaporative losses from the Geonor-Evap gauge exceeded accumulated precipitation, with an average loss of 0.12 mm h-1. The impact of evaporation on precipitation measurements was sensitive to the choice of calculation method. In general, the pairwise method that utilized a longer time series to smooth out sensor noise was more sensitive to gauge evaporation (-4.6% bias with respect to control) than the weighted-average method that calculated depth change over a smaller window (<+1% bias). These results indicate that while climate and gauge design affect gauge evaporation rates, computational methods also influence the magnitude of evaporation biases on precipitation measurements. This study can be used to advance quality insurance (QA) techniques used in other automated networks to mitigate the impact of evaporation biases on precipitation measurements.

Synoptic moisture pathways associated with mean and extreme precipitation over Canada for winter and spring

NASA Astrophysics Data System (ADS)

Tan, X.; Gan, T. Y. Y.; Chen, Y. D.

2017-12-01

Dominant synoptic moisture pathway patterns of vertically integrated water vapor transport (IVT) in winter and spring over Canada West and East were identified using the self-organizing map method. Large-scale meteorological patterns (LSMPs) were related to the variability in seasonal precipitation totals and occurrences of precipitation extremes. Changes in both occurrences of LSMPs and seasonal precipitation occurred under those LSMPs were evaluated to attribute observed changes in seasonal precipitation totals and occurrences of precipitation extremes. Effects of large-scale climate anomalies on occurrences of LSMPs were also examined. Results show that synoptic moisture pathways and LSMPs exhibit the propagation of jet streams as the location and direction of ridges and troughs, and the strength and center of pressure lows and highs varied considerably between LSMPs. Significant decreases in occurrences of synoptic moisture pathway patterns that are favorable with positive precipitation anomalies and more precipitation extremes in winter over Canada West resulted in decreases in seasonal precipitation and occurrences of precipitation extremes. LSMPs resulting in a hot and dry climate and less (more) frequent precipitation extremes over the Canadian Prairies in winter and northwestern Canada in spring are more likely to occur in years with a negative phase of PNA. Occurrences of LSMPs for a wet climate and frequent occurrences of extreme precipitation events over southeastern Canada are associated with a positive phase of NAO. In El Niño years or negative PDO years, LSMPs associated with a dry climate and less frequent precipitation extremes over western Canada tend to occur.

Impacts of correcting the inter-variable correlation of climate model outputs on hydrological modeling

NASA Astrophysics Data System (ADS)

Chen, Jie; Li, Chao; Brissette, François P.; Chen, Hua; Wang, Mingna; Essou, Gilles R. C.

2018-05-01

Bias correction is usually implemented prior to using climate model outputs for impact studies. However, bias correction methods that are commonly used treat climate variables independently and often ignore inter-variable dependencies. The effects of ignoring such dependencies on impact studies need to be investigated. This study aims to assess the impacts of correcting the inter-variable correlation of climate model outputs on hydrological modeling. To this end, a joint bias correction (JBC) method which corrects the joint distribution of two variables as a whole is compared with an independent bias correction (IBC) method; this is considered in terms of correcting simulations of precipitation and temperature from 26 climate models for hydrological modeling over 12 watersheds located in various climate regimes. The results show that the simulated precipitation and temperature are considerably biased not only in the individual distributions, but also in their correlations, which in turn result in biased hydrological simulations. In addition to reducing the biases of the individual characteristics of precipitation and temperature, the JBC method can also reduce the bias in precipitation-temperature (P-T) correlations. In terms of hydrological modeling, the JBC method performs significantly better than the IBC method for 11 out of the 12 watersheds over the calibration period. For the validation period, the advantages of the JBC method are greatly reduced as the performance becomes dependent on the watershed, GCM and hydrological metric considered. For arid/tropical and snowfall-rainfall-mixed watersheds, JBC performs better than IBC. For snowfall- or rainfall-dominated watersheds, however, the two methods behave similarly, with IBC performing somewhat better than JBC. Overall, the results emphasize the advantages of correcting the P-T correlation when using climate model-simulated precipitation and temperature to assess the impact of climate change on watershed hydrology. However, a thorough validation and a comparison with other methods are recommended before using the JBC method, since it may perform worse than the IBC method for some cases due to bias nonstationarity of climate model outputs.

Extreme Precipitation and Flooding: Exposure Characterization and the Association Between Exposure and Mortality in 108 United States Communities, 1987-2005

NASA Astrophysics Data System (ADS)

Severson, R. L.; Peng, R. D.; Anderson, G. B.

2017-12-01

There is substantial evidence that extreme precipitation and flooding are serious threats to public health and safety. These threats are predicted to increase with climate change. Epidemiological studies investigating the health effects of these events vary in the methods used to characterize exposure. Here, we compare two sources of precipitation data (National Oceanic and Atmospheric Administration (NOAA) station-based and North American Land Data Assimilation Systems (NLDAS-2) Reanalysis data-based) for estimating exposure to extreme precipitation and two sources of flooding data, based on United States Geological Survey (USGS) streamflow gages and the NOAA Storm Events database. We investigate associations between each of the four exposure metrics and short-term risk of four causes of mortality (accidental, respiratory-related, cardiovascular-related, and all-cause) in the United States from 1987 through 2005. Average daily precipitation values from the two precipitation data sources were moderately correlated (Spearman's rho = 0.74); however, values from the two data sources were less correlated when comparing binary metrics of exposure to extreme precipitation days (Jaccard index (J) = 0.35). Binary metrics of daily flood exposure were poorly correlated between the two flood data sources (Spearman's rho = 0.07; J = 0.05). There was little correlation between extreme precipitation exposure and flood exposure in study communities. We did not observe evidence of a positive association between any of the four exposure metrics and risk of any of the four mortality outcomes considered. Our results suggest, due to the observed lack of agreement between different extreme precipitation and flood metrics, that exposure to extreme precipitation may not serve as an effective surrogate for exposures related to flooding. Furthermore, It is possible that extreme precipitation and flood exposures may often be too localized to allow accurate exposure assessment at the community level for epidemiological studies.

Strengthening Mechanisms and Their Relative Contributions to the Yield Strength of Microalloyed Steels

NASA Astrophysics Data System (ADS)

Lu, Junfang; Omotoso, Oladipo; Wiskel, J. Barry; Ivey, Douglas G.; Henein, Hani

2012-09-01

Microalloyed steels are used widely in oil and gas pipelines. They are a class of high-strength, low-carbon steels that contain small additions (in amounts less than 0.1 wt pct) of Nb, Ti, and/or V. The steels may contain other alloying elements, such as Mo, in amounts exceeding 0.1 wt pct. Precipitation in these steels can be controlled through thermomechanical-controlled processing, leading to precipitates with sizes that range from several microns to a few nanometers. Microalloyed steels have good strength, good toughness, and excellent weldability, which are attributed in part to the presence of the nanosized carbide and carbonitride precipitates. Because of their fine sizes, wide particle size distribution, and low volume fractions, conventional microscopic methods are not satisfactory for quantifying these precipitates. Matrix dissolution is a promising alternative to extract the precipitates for quantification. Relatively large volumes of material can be analyzed so that statistically significant quantities of precipitates of different sizes are collected. In this article, the microstructure features of a series of microalloyed steels (X70, X80, and X100) as well as a Grade 100 steel are characterized using optical microscopy (OM) and scanning electron microscopy (SEM). A chemical dissolution technique is used to extract the precipitates from the steels. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) are combined to analyze the chemical composition of these precipitates. Rietveld refinement of the XRD patterns is used to quantify fully the relative amounts of these precipitates. The size distribution of the nanosized precipitates is quantified using dark-field imaging (DF) in the TEM. The effects of microalloying content, finish rolling temperature (FRT), and coiling temperature (CT)/interrupted cooling temperature (ICT) on the grain size and the amount of nanoprecipitation are discussed. Individual strengthening contributions from grain size effects, solid-solution strengthening, and precipitation strengthening are quantified to understand fully the strengthening mechanisms for these steels.

Recovery of nickel and cobalt as MHP from limonitic ore leaching solution: Kinetics analysis and precipitate characterization

NASA Astrophysics Data System (ADS)

Safitri, Nina; Mubarok, M. Zaki; Winarko, Ronny; Tanlega, Zela

2018-05-01

In the present study, precipitation of nickel and cobalt as mixed hydroxide precipitate (MHP) from pregnant leach solution of nickel limonite ore from Soroako after iron removal stage was carried out. A series of MHP precipitation experiments was conducted by using MgO slurry as neutralizing agent and the effects of pH, temperature, duration of precipitation and the addition of MHP seed on the precipitation behavior of nickel, cobalt, as well as iron and manganese was studied. Characterization of MHP product was performed by particle size analyzer (PSA) as well as X-Ray Fluorescence (XRF), X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM) analyses. Kinetics analysis was made by using differential-integral method for the rate of homogenous reaction. Precipitation at pH 7, temperature 50°C for 30 minute, without seed addition resulted in nickel and cobalt recoveries of 82.8% and 92%, respectively with co-precipitated iron and manganese of 70% and 24.2%, respectively. The seed addition increases nickel and cobalt precipitations significantly to 99.9% and 99.1%, respectively. However, the addition of seed into led to a significant increase of manganese co-precipitation from 24.2% without seed addition to 39.5% at the addition of 1 g seed per 200 mL of PLS. Kinetics analysis revealed that Ni precipitation to form MHP follows the second-order reaction kinetics with activation energy of 94.6 kJ/mol.

Study on camel IgG purification

PubMed Central

Khamehchian, Sedigheh; Zolfagharian, Hossein; Dounighi, Naser Mohammadpour; Tebianian, Majid; Madani, Rasool

2014-01-01

A combined process of ammonium sulfate precipitation (salting out) and ion-exchange chromatography on DEAE-Sepharose CL-6B was used to prepare camel antivenom (IgG) against Naja Naja Oxiana for therapy. In the ammonium sulfate precipitation, the best condition for fractionation of IgG from the other proteins in camel serum was 55% precipitate. The camel IgG presented as 2 bands with molecular masses of 250 and 100 kDa, the latter corresponding to heavy chain IgG, on 10% gel electrophoresis. A trace amount of non-IgG proteins was not isolated and remained in this precipitate. Therefore in order to effectively separate albumin and the other nonspecific proteins from the IgG, the 25% precipitate of ammonium sulfate precipitation of serum was subjected to DEAE-Sepharose CL-6B column chromatography. A peak of antibody (IgG) could be obtained by elution with sodium phosphate buffer. In this stage, 2 bands of molecular masses of 150 and 75 kDa were observed on 7% gel electrophoresis. A comparative study was performed between camel IgG and conventional horse F(ab)2 antivenoms in term of potency (serum neutralization test and ELISA). Our results showed that the potency of camel antivenom was 4-fold higher than that of horse. It is suggested the combined ammonium sulfate precipitation and ion-exchange chromatography process effectively removed residual proteins in the final camel IgG preparation and can be a suitable method for large-scale refinement of therapeutic camel antivenoms. PMID:24642472

How does bias correction of regional climate model precipitation affect modelled runoff?

NASA Astrophysics Data System (ADS)

Teng, J.; Potter, N. J.; Chiew, F. H. S.; Zhang, L.; Wang, B.; Vaze, J.; Evans, J. P.

2015-02-01

Many studies bias correct daily precipitation from climate models to match the observed precipitation statistics, and the bias corrected data are then used for various modelling applications. This paper presents a review of recent methods used to bias correct precipitation from regional climate models (RCMs). The paper then assesses four bias correction methods applied to the weather research and forecasting (WRF) model simulated precipitation, and the follow-on impact on modelled runoff for eight catchments in southeast Australia. Overall, the best results are produced by either quantile mapping or a newly proposed two-state gamma distribution mapping method. However, the differences between the methods are small in the modelling experiments here (and as reported in the literature), mainly due to the substantial corrections required and inconsistent errors over time (non-stationarity). The errors in bias corrected precipitation are typically amplified in modelled runoff. The tested methods cannot overcome limitations of the RCM in simulating precipitation sequence, which affects runoff generation. Results further show that whereas bias correction does not seem to alter change signals in precipitation means, it can introduce additional uncertainty to change signals in high precipitation amounts and, consequently, in runoff. Future climate change impact studies need to take this into account when deciding whether to use raw or bias corrected RCM results. Nevertheless, RCMs will continue to improve and will become increasingly useful for hydrological applications as the bias in RCM simulations reduces.

High-resolution speleothem record of precipitation from the Yucatan Peninsula spanning the Maya Preclassic Period

NASA Astrophysics Data System (ADS)

Medina-Elizalde, Martín; Burns, Stephen J.; Polanco-Martínez, Josué M.; Beach, Timothy; Lases-Hernández, Fernanda; Shen, Chuan-Chou; Wang, Hao-Cheng

2016-03-01

We produced a new high-resolution absolute U-Th dated stalagmite oxygen isotope record (δ18O) from Río Secreto, Playa del Carmen, Yucatan Peninsula (YP). This new 1434-year stalagmite record (named Itzamna after the Maya god of creation) spans the time interval between BCE 1037 and CE 397 with an average resolution of 8 ± 2 years. It provides a novel view of climate evolution over the Preclassic and early Classic periods in Maya history. To understand the controls of regional precipitation δ18O on seasonal time scales, we characterized the amount effect between precipitation amount (P) and precipitation δ18O (δP). We found that precipitation δ18O in the Yucatan Peninsula is controlled by the amount effect on seasonal scales (δP/ΔP = - 0.0137 ± 0.0031‰ per mm, r = 0.9), as suspected but never before demonstrated. Cave drip δ18O is consistent with the annual amount-weighted δ18O composition of precipitation. Multiple lines of evidence suggest that stalagmite δ18O reflects isotopic equilibrium conditions and thus stalagmite δ18O changes are interpreted to reflect precipitation amount. We determined quantitative precipitation changes from the stalagmite δ18O record following previous methods (Medina-Elizalde and Rohling, 2012). The stalagmite precipitation record suggests twelve periods of anomalous precipitation reductions ranging between about 30 and 70% below mean conditions at the time and with durations from 6 years to 31 years. Between BCE 520 and 166, the speleothem precipitation record suggests that the YP experienced an interval of high precipitation labeled the Late Preclassic Humid Period (LPHP) with precipitation maxima of up to + 86 ± 20%. Preclassic Maya cultural expansion in El Mirador Basin, located in northern Guatemala, took place while the peninsula transitioned from the LPHP to an interval with below average precipitation. We find that the Preclassic abandonment of major centers in the Mirador Basin and others around the Maya Lowlands was synchronous with two unprecedented multi-decadal events of severe precipitation reduction with magnitudes of - 55 ± 13% and - 49 ± 12 and centered at CE 186 and 234, respectively. We also find evidence that centennial scale precipitation variability in the YP during the Preclassic Period may have been associated with shifts in rainfall fluxes from Atlantic tropical cyclones.

[Study on X-ray powder diffraction of various structured zinc titanate prepared by the method of direct precipitation].

PubMed

Guo, Jian; Wang, Zhi-hua; Tao, Dong-liang; Guo, Guang-sheng

2007-05-01

Zinc titanate powders were prepared from Ti(SO4)2, Zn(NO3)2 x (6)H2O and (NH4)2CO3 by the method of direct precipitation. The effects of reaction conditions on the structure of zinc titanate were studied. The sample was analyzed by means of XRD and TG-DTA. The structure of zinc titanate was affected by the reaction subsequence of the formation of titanic acid and zinc carbonate. In the reaction system where titanic acid was generated earlier, collision reaction occurred between the generated zinc carbonate molecule and the surrounding titanic acid molecule. When titanic acid was generated earlier and precipitant (NH4)2CO3 was sufficient, Zn2Ti3O8 was obtained because of the sufficient collision reaction and superfluous titanic acid. In the reaction system where zinc carbonate was generated earlier, collision reaction occurred between the generated titanic acid molecule and the surrounding zinc carbonate molecule. When zinc carbonate was generated earlier and precipitant (NH4)2CO3 was sufficient, Zn2TiO4 was obtained because of the sufficient collision reaction and superfluous zinc carbonate. In addition, the kinds and structure of the production were affected by the dosage of precipitant and the reaction temperature. Zn2Ti3O8 or Zn2TiO4 could be obtained easier when using more precipitant or higher reaction temperature which could cause more sufficient collision reaction. ZnTiO3 could be obtained under the conditions of less precipitant and lower reaction temperature.

Pore-scale simulation of calcium carbonate precipitation and dissolution under highly supersaturated conditions in a microfludic pore network

NASA Astrophysics Data System (ADS)

Yoon, H.; Dewers, T. A.; Valocchi, A. J.; Werth, C. J.

2011-12-01

Dissolved CO2 during geological CO2 storage may react with minerals in fractured rocks or confined aquifers and cause mineral precipitation. The overall rate of reaction can be affected by coupled processes among hydrodynamics, transport, and reactions at pore-scale. Pore-scale models of coupled fluid flow, reactive transport, and CaCO3 precipitation and dissolution are applied to account for transient experimental results of CaCO3 precipitation and dissolution under highly supersaturated conditions in a microfluidic pore network (i.e., micromodel). Pore-scale experiments in the micromodel are used as a basis for understanding coupled physics of systems perturbed by geological CO2 injection. In the micromodel, precipitation is induced by transverse mixing along the centerline in pore bodies. Overall, the pore-scale model qualitatively captured the governing physics of reactions such as precipitate morphology, precipitation rate, and maximum precipitation area in first few pore spaces. In particular, we found that proper estimation of the effective diffusion coefficient and the reactive surface area is necessary to adequately simulate precipitation and dissolution rates. As the model domain increases, the effect of flow patterns affected by precipitation on the overall reaction rate also increases. The model is also applied to account for the effect of different reaction rate laws on mineral precipitation and dissolution at pore-scale. Reaction rate laws tested include the linear rate law, nonlinear power law, and newly-developed rate law based on in-situ measurements at nano scale in the literature. Progress on novel methods for upscaling pore-scale models for reactive transport are discussed, and are being applied to mineral precipitation patterns observed in natural analogues. H.Y. and T. D. were supported as part of the Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001114. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Radar-derived quantitative precipitation estimation in complex terrain over the eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Gou, Yabin; Ma, Yingzhao; Chen, Haonan; Wen, Yixin

2018-05-01

Quantitative precipitation estimation (QPE) is one of the important applications of weather radars. However, in complex terrain such as Tibetan Plateau, it is a challenging task to obtain an optimal Z-R relation due to the complex spatial and temporal variability in precipitation microphysics. This paper develops two radar QPE schemes respectively based on Reflectivity Threshold (RT) and Storm Cell Identification and Tracking (SCIT) algorithms using observations from 11 Doppler weather radars and 3264 rain gauges over the Eastern Tibetan Plateau (ETP). These two QPE methodologies are evaluated extensively using four precipitation events that are characterized by different meteorological features. Precipitation characteristics of independent storm cells associated with these four events, as well as the storm-scale differences, are investigated using short-term vertical profile of reflectivity (VPR) clusters. Evaluation results show that the SCIT-based rainfall approach performs better than the simple RT-based method for all precipitation events in terms of score comparison using validation gauge measurements as references. It is also found that the SCIT-based approach can effectively mitigate the local error of radar QPE and represent the precipitation spatiotemporal variability better than the RT-based scheme.

Multi-scale fluctuation analysis of precipitation in Beijing by Extreme-point Symmetric Mode Decomposition

NASA Astrophysics Data System (ADS)

Li, Jiqing; Duan, Zhipeng; Huang, Jing

2018-06-01

With the aggravation of the global climate change, the shortage of water resources in China is becoming more and more serious. Using reasonable methods to study changes in precipitation is very important for planning and management of water resources. Based on the time series of precipitation in Beijing from 1951 to 2015, the multi-scale features of precipitation are analyzed by the Extreme-point Symmetric Mode Decomposition (ESMD) method to forecast the precipitation shift. The results show that the precipitation series have periodic changes of 2.6, 4.3, 14 and 21.7 years, and the variance contribution rate of each modal component shows that the inter-annual variation dominates the precipitation in Beijing. It is predicted that precipitation in Beijing will continue to decrease in the near future.

Studying precipitation recycling over the Tibetan Plateau using evaporation-tagging and back-trajectory analysis

NASA Astrophysics Data System (ADS)

Gao, Y.

2017-12-01

Regional precipitation recycling (i.e., the contribution of local evaporation to local precipitation) is an important component of water cycle over the Tibetan Plateau (TP). Two methods were used to investigate regional precipitation recycling: 1) tracking of tagged atmospheric water parcels originating from evaporation in a source region (i.e., E-tagging), and 2) back-trajectory approach to track the evaporative sources contributed to precipitation in a specific region. These two methods were applied to Weather Research and Forecasting (WRF) regional climate simulations to quantify the precipitation recycling ratio in the TP for three selected years: climatologically normal, dry and wet year. The simulation region is characterized by high average elevation above 4000 m and complex terrain. The back-trajectory approach is also calculated over three sub-regions over the TP: namely western, northeastern and southeastern TP, and the E-tagging approach could provide recycling-ratio distributions over the whole TP. Three aspects are investigated to characterize the precipitation recycling: annual mean, seasonal variations and spatial distributions. Averaged over the TP, the precipitation recycling ratio estimated by the E-tagging approach is higher than that from the back-trajectory method. The back-trajectory approach uses a precipitation threshold as total precipitation in five days divided by a random number, and this number was set to 500 as a tread off between equilibrium and computational efficiency. Lower recycling ratio derived from the back-trajectory approach is related to the precipitation threshold used. The E-tagging, however, tracks every air parcel of evaporation regardless of the precipitation amount. There is no obvious seasonal variation in the recycling ratio using both methods. The E-tagging approach shows high recycling ratios in the center TP, indicating stronger land-atmospheric interactions than elsewhere.

Development and Validation of HPLC Method for Determination of Crocetin, a constituent of Saffron, in Human Serum Samples

PubMed Central

Mohammadpour, Amir Hooshang; Ramezani, Mohammad; Tavakoli Anaraki, Nasim; Malaekeh-Nikouei, Bizhan; Amel Farzad, Sara; Hosseinzadeh, Hossein

2013-01-01

Objective(s): The present study reports the development and validation of a sensitive and rapid extraction method beside high performance liquid chromatographic method for the determination of crocetin in human serum. Materials and Methods: The HPLC method was carried out by using a C18 reversed-phase column and a mobile phase composed of methanol/water/acetic acid (85:14.5:0.5 v/v/v) at the flow rate of 0.8 ml/min. The UV detector was set at 423 nm and 13-cis retinoic acid was used as the internal standard. Serum samples were pretreated with solid-phase extraction using Bond Elut C18 (200mg) cartridges or with direct precipitation using acetonitrile. Results: The calibration curves were linear over the range of 0.05-1.25 µg/ml for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction. The mean recoveries of crocetin over a concentration range of 0.05-5 µg/ml serum for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction were above 70 % and 60 %, respectively. The intraday coefficients of variation were 0.37- 2.6% for direct precipitation method and 0.64 - 5.43% for solid-phase extraction. The inter day coefficients of variation were 1.69 – 6.03% for direct precipitation method and 5.13-12.74% for solid-phase extraction, respectively. The lower limit of quantification for crocetin was 0.05 µg/ml for direct precipitation method and 0.5 µg/ml for solid-phase extraction. Conclusion: The validated direct precipitation method for HPLC satisfied all of the criteria that were necessary for a bioanalytical method and could reliably quantitate crocetin in human serum for future clinical pharmacokinetic study. PMID:23638292

Emulsifying and foaming properties of amaranth seed protein isolates.

PubMed

Fidantsi, A; Doxastakis, G

2001-07-01

The emulsifying and foaming properties of amaranth seed protein isolates prepared by wet extraction methods, such as isoelectric precipitation and dialysis, were investigated. The various isolates differ from each other in many ways. The isolate prepared by isoelectric precipitation mainly contains the globulin but not the albumin fraction and a considerable amount of polysaccharides, while the other isolate prepared by the dialysis method contains all the globulin and albumin fractions. The protein-polysaccharide complexes enhance emulsion stability due to steric repulsion effects. Measurements of the emulsion stability show that the studied protein isolates act as effective stabilizing agents. Foam expansion is dominated by the surface activity and availability of protein in the solution, while foam stability is determined by the properties of the interfacial layer. The results show that amaranth protein isolates act as an effective foaming agent. Both foaming properties intensified from the presence of protein-polysaccharide complexes.

Research on the technical requirements standards of high efficiency precipitator in power industries for assessment

NASA Astrophysics Data System (ADS)

Jin, Huang; Ling, Lin; Jun, Guo; Jianguo, Li; Yongzhong, Wang

2017-11-01

Facing the increasingly severe situation of air pollution, China are now positively promoting the evaluation of high efficiency air pollution control equipments and the research of the relative national standards. This paper showed the significance and the effect of formulating the technical requirements of high efficiency precipitator equipments for assessment national standards in power industries as well as the research thoughts and principle of these standards. It introduce the qualitative and quantitative evaluation requirements of high efficiency precipitators using in power industries and the core technical content such as testing, calculating, evaluation methods and so on. The implementation of a series of national standards is in order to lead and promote the production and application of high efficiency precipitator equipments in the field of the prevention of air pollution in national power industries.

GPS-based PWV for precipitation forecasting and its application to a typhoon event

NASA Astrophysics Data System (ADS)

Zhao, Qingzhi; Yao, Yibin; Yao, Wanqiang

2018-01-01

The temporal variability of precipitable water vapour (PWV) derived from Global Navigation Satellite System (GNSS) observations can be used to forecast precipitation events. A number of case studies of precipitation events have been analysed in Zhejiang Province, and a forecasting method for precipitation events was proposed. The PWV time series retrieved from the Global Positioning System (GPS) observations was processed by using a least-squares fitting method, so as to obtain the line tendency of ascents and descents over PWV. The increment of PWV for a short time (two to six hours) and PWV slope for a longer time (a few hours to more than ten hours) during the PWV ascending period are considered as predictive factors with which to forecast the precipitation event. The numerical results show that about 80%-90% of precipitation events and more than 90% of heavy rain events can be forecasted two to six hours in advance of the precipitation event based on the proposed method. 5-minute PWV data derived from GPS observations based on real-time precise point positioning (RT-PPP) were used for the typhoon event that passed over Zhejiang Province between 10 and 12 July, 2015. A good result was acquired using the proposed method and about 74% of precipitation events were predicted at some ten to thirty minutes earlier than their onset with a false alarm rate of 18%. This study shows that the GPS-based PWV was promising for short-term and now-casting precipitation forecasting.

Effects of Precipitant and pH on Coprecipitation of Nanosized Co-Cr-V Alloy Powders.

PubMed

Chen, Xiaoyu; Li, Yongxia; Huang, Lan; Zou, Dan; Wu, Enxi; Liu, Yanjun; Xie, Yuanyan; Yao, Rui; Liao, Songyi; Wang, Guangrong; Zheng, Feng

2017-09-21

Nanosized Co-Cr-V alloy powders were synthesized via coprecipitation method. Effects of precipitants ((NH₄)₂C₂O₄·H₂O and Na₂CO₃) and pH were investigated by X-ray diffraction (XRD), Zeta potential analyzer, thermogravimetry-differential scanning calorimetry (TG-DSC), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). Co-Cr-V alloy powders were consisted of major face-centered cubic Co (fcc Co) and minor hexagonal close-packed Co (hcp Co). Grain sizes of precursors and Co-Cr-V alloy powders were increased with pH value (7-10) within the ranges of 3~39 and 39~66 nm, respectively. Rod-like or granular Co-Cr-V alloy particles were assembled by interconnected nanograins. At pH = 7, Na₂CO₃ precipitant was found to be beneficial to maintain the desirable composition of Co-Cr-V powders. It was also found that lower pH favors the maintenance of pre-designed composition, while grain coarsens at higher pH. Effects of variation for precipitant and pH on the morphology and composition of Co-Cr-V alloy powder were discussed in detail and relevant mechanism was further proposed.

Information theory-based decision support system for integrated design of multivariable hydrometric networks

NASA Astrophysics Data System (ADS)

Keum, Jongho; Coulibaly, Paulin

2017-07-01

Adequate and accurate hydrologic information from optimal hydrometric networks is an essential part of effective water resources management. Although the key hydrologic processes in the water cycle are interconnected, hydrometric networks (e.g., streamflow, precipitation, groundwater level) have been routinely designed individually. A decision support framework is proposed for integrated design of multivariable hydrometric networks. The proposed method is applied to design optimal precipitation and streamflow networks simultaneously. The epsilon-dominance hierarchical Bayesian optimization algorithm was combined with Shannon entropy of information theory to design and evaluate hydrometric networks. Specifically, the joint entropy from the combined networks was maximized to provide the most information, and the total correlation was minimized to reduce redundant information. To further optimize the efficiency between the networks, they were designed by maximizing the conditional entropy of the streamflow network given the information of the precipitation network. Compared to the traditional individual variable design approach, the integrated multivariable design method was able to determine more efficient optimal networks by avoiding the redundant stations. Additionally, four quantization cases were compared to evaluate their effects on the entropy calculations and the determination of the optimal networks. The evaluation results indicate that the quantization methods should be selected after careful consideration for each design problem since the station rankings and the optimal networks can change accordingly.

Linking precipitation, evapotranspiration and soil moisture content for the improvement of predictability over land

NASA Astrophysics Data System (ADS)

Catalano, Franco; Alessandri, Andrea; De Felice, Matteo

2013-04-01

Climate change scenarios are expected to show an intensification of the hydrological cycle together with modifications of evapotranspiration and soil moisture content. Evapotranspiration changes have been already evidenced for the end of the 20th century. The variance of evapotranspiration has been shown to be strongly related to the variance of precipitation over land. Nevertheless, the feedbacks between evapotranspiration, soil moisture and precipitation have not yet been completely understood at present-day. Furthermore, soil moisture reservoirs are associated to a memory and thus their proper initialization may have a strong influence on predictability. In particular, the linkage between precipitation and soil moisture is modulated by the effects on evapotranspiration. Therefore, the investigation of the coupling between these variables appear to be of primary importance for the improvement of predictability over the continents. The coupled manifold (CM) technique (Navarra and Tribbia 2005) is a method designed to separate the effects of the variability of two variables which are connected. This method has proved to be successful for the analysis of different climate fields, like precipitation, vegetation and sea surface temperature. In particular, the coupled variables reveal patterns that may be connected with specific phenomena, thus providing hints regarding potential predictability. In this study we applied the CM to recent observational datasets of precipitation (from CRU), evapotranspiration (from GIMMS and MODIS satellite-based estimates) and soil moisture content (from ESA) spanning a time period of 23 years (1984-2006) with a monthly frequency. Different data stratification (monthly, seasonal, summer JJA) have been employed to analyze the persistence of the patterns and their characteristical time scales and seasonality. The three variables considered show a significant coupling among each other. Interestingly, most of the signal of the evapotranspiration-precipitation coupled terms comes from the summer (JJA), when convective motions increase sensitivity to surface conditions over land. The CM analysis of the response of evapotranspiration to soil moisture allowed a characterization of the robustness of the coupling between these two variables which has been identified as a key requirement for precipitation predictability (Koster et al. 2000). References Navarra, A., and J. Tribbia (2005), The coupled manifold, J. Atmos. Sci., 62, 310-330. Koster, R. D., M. J. Suarez, and M. Heiser (2000), Variance and predictability of precipitation at seasonal-to-interannual timescales, J. Hydrometeor., 1, 26-46.

Spatiotemporal analysis the precipitation extremes affecting rice yield in Jiangsu province, southeast China

NASA Astrophysics Data System (ADS)

Huang, Jin; Islam, A. R. M. Towfiqul; Zhang, Fangmin; Hu, Zhenghua

2017-10-01

With the increasing risk of meteorological disasters, it is of great importance to analyze the spatiotemporal changes of precipitation extremes and its possible impact on rice productivity, especially in Jiangsu province, southeast China. In this study, we explored the relationships between rice yield and extreme precipitation indices using Mann-Kendall trend test, Pettitt's test, and K-means clustering methods. This study used 10 extreme precipitation indices of the rice growing season (May to October) based on the daily precipitation records and rice yield data at 52 meteorological stations during 1961-2012 in Jiangsu province. The main findings were as follows: (1) correlation results indicated that precipitation extremes occurred in the months of July, August, and October, which had noticeable adverse effects on rice yield; (2) the maximum 7-day precipitation of July and the number of rainy days of August and October should be considered as three key indicators for the precipitation-induced rice meteorological disasters; and (3) most of the stations showed an increasing trends for the maximum 7-day precipitation of July and the number of rainy days of August, while the number of rainy days of October in all the stations demonstrated a decreasing trend. Moreover, Jiangsu province could be divided into two major sub-regions such as north and south areas with different temporal variations in the three key indicators.

Model Parameter Estimation Using Ensemble Data Assimilation: A Case with the Nonhydrostatic Icosahedral Atmospheric Model NICAM and the Global Satellite Mapping of Precipitation Data

NASA Astrophysics Data System (ADS)

Kotsuki, Shunji; Terasaki, Koji; Yashiro, Hasashi; Tomita, Hirofumi; Satoh, Masaki; Miyoshi, Takemasa

2017-04-01

This study aims to improve precipitation forecasts from numerical weather prediction (NWP) models through effective use of satellite-derived precipitation data. Kotsuki et al. (2016, JGR-A) successfully improved the precipitation forecasts by assimilating the Japan Aerospace eXploration Agency (JAXA)'s Global Satellite Mapping of Precipitation (GSMaP) data into the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) at 112-km horizontal resolution. Kotsuki et al. mitigated the non-Gaussianity of the precipitation variables by the Gaussian transform method for observed and forecasted precipitation using the previous 30-day precipitation data. This study extends the previous study by Kotsuki et al. and explores an online estimation of model parameters using ensemble data assimilation. We choose two globally-uniform parameters, one is the cloud-to-rain auto-conversion parameter of the Berry's scheme for large scale condensation and the other is the relative humidity threshold of the Arakawa-Schubert cumulus parameterization scheme. We perform the online-estimation of the two model parameters with an ensemble transform Kalman filter by assimilating the GSMaP precipitation data. The estimated parameters improve the analyzed and forecasted mixing ratio in the lower troposphere. Therefore, the parameter estimation would be a useful technique to improve the NWP models and their forecasts. This presentation will include the most recent progress up to the time of the symposium.

X-ray peak profile analysis of zinc oxide nanoparticles formed by simple precipitation method

NASA Astrophysics Data System (ADS)

Pelicano, Christian Mark; Rapadas, Nick Joaquin; Magdaluyo, Eduardo

2017-12-01

Zinc oxide (ZnO) nanoparticles were successfully synthesized by a simple precipitation method using zinc acetate and tetramethylammonium hydroxide. The synthesized ZnO nanoparticles were characterized by X-ray Diffraction analysis (XRD) and Transmission Electron Microscopy (TEM). The XRD result revealed a hexagonal wurtzite structure for the ZnO nanoparticles. The TEM image showed spherical nanoparticles with an average crystallite size of 6.70 nm. For x-ray peak analysis, Williamson-Hall (W-H) and Size-Strain Plot (SSP) methods were applied to examine the effects of crystallite size and lattice strain on the peak broadening of the ZnO nanoparticles. Based on the calculations, the estimated crystallite sizes and lattice strains obtained are in good agreement with each other.

Geographically weighted regression based methods for merging satellite and gauge precipitation

NASA Astrophysics Data System (ADS)

Chao, Lijun; Zhang, Ke; Li, Zhijia; Zhu, Yuelong; Wang, Jingfeng; Yu, Zhongbo

2018-03-01

Real-time precipitation data with high spatiotemporal resolutions are crucial for accurate hydrological forecasting. To improve the spatial resolution and quality of satellite precipitation, a three-step satellite and gauge precipitation merging method was formulated in this study: (1) bilinear interpolation is first applied to downscale coarser satellite precipitation to a finer resolution (PS); (2) the (mixed) geographically weighted regression methods coupled with a weighting function are then used to estimate biases of PS as functions of gauge observations (PO) and PS; and (3) biases of PS are finally corrected to produce a merged precipitation product. Based on the above framework, eight algorithms, a combination of two geographically weighted regression methods and four weighting functions, are developed to merge CMORPH (CPC MORPHing technique) precipitation with station observations on a daily scale in the Ziwuhe Basin of China. The geographical variables (elevation, slope, aspect, surface roughness, and distance to the coastline) and a meteorological variable (wind speed) were used for merging precipitation to avoid the artificial spatial autocorrelation resulting from traditional interpolation methods. The results show that the combination of the MGWR and BI-square function (MGWR-BI) has the best performance (R = 0.863 and RMSE = 7.273 mm/day) among the eight algorithms. The MGWR-BI algorithm was then applied to produce hourly merged precipitation product. Compared to the original CMORPH product (R = 0.208 and RMSE = 1.208 mm/hr), the quality of the merged data is significantly higher (R = 0.724 and RMSE = 0.706 mm/hr). The developed merging method not only improves the spatial resolution and quality of the satellite product but also is easy to implement, which is valuable for hydrological modeling and other applications.

Phase-field simulations of coherent precipitate morphologies and coarsening kinetics

NASA Astrophysics Data System (ADS)

Vaithyanathan, Venugopalan

2002-09-01

The primary aim of this research is to enhance the fundamental understanding of coherent precipitation reactions in advanced metallic alloys. The emphasis is on a particular class of precipitation reactions which result in ordered intermetallic precipitates embedded in a disordered matrix. These precipitation reactions underlie the development of high-temperature Ni-base superalloys and ultra-light aluminum alloys. Phase-field approach, which has emerged as the method of choice for modeling microstructure evolution, is employed for this research with the focus on factors that control the precipitate morphologies and coarsening kinetics, such as precipitate volume fractions and lattice mismatch between precipitates and matrix. Two types of alloy systems are considered. The first involves L1 2 ordered precipitates in a disordered cubic matrix, in an attempt to model the gamma' precipitates in Ni-base superalloys and delta' precipitates in Al-Li alloys. The effect of volume fraction on coarsening kinetics of gamma' precipitates was investigated using two-dimensional (2D) computer simulations. With increase in volume fraction, larger fractions of precipitates were found to have smaller aspect ratios in the late stages of coarsening, and the precipitate size distributions became wider and more positively skewed. The most interesting result was associated with the effect of volume fraction on the coarsening rate constant. Coarsening rate constant as a function of volume fraction extracted from the cubic growth law of average half-edge length was found to exhibit three distinct regimes: anomalous behavior or decreasing rate constant with volume fraction at small volume fractions ( ≲ 20%), volume fraction independent or constant behavior for intermediate volume fractions (˜20--50%), and the normal behavior or increasing rate constant with volume fraction for large volume fractions ( ≳ 50%). The second alloy system considered was Al-Cu with the focus on understanding precipitation of metastable tetragonal theta'-Al 2Cu in a cubic Al solid solution matrix. In collaboration with Chris Wolverton at Ford Motor Company, a multiscale model, which involves a novel combination of first-principles atomistic calculations with a mesoscale phase-field microstructure model, was developed. Reliable energetics in the form of bulk free energy, interfacial energy and parameters for calculating the elastic energy were obtained using accurate first-principles calculations. (Abstract shortened by UMI.)

A decision tree algorithm for investigation of model biases related to dynamical cores and physical parameterizations: CESM/CAM EVALUATION BY DECISION TREES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soner Yorgun, M.; Rood, Richard B.

An object-based evaluation method using a pattern recognition algorithm (i.e., classification trees) is applied to the simulated orographic precipitation for idealized experimental setups using the National Center of Atmospheric Research (NCAR) Community Atmosphere Model (CAM) with the finite volume (FV) and the Eulerian spectral transform dynamical cores with varying resolutions. Daily simulations were analyzed and three different types of precipitation features were identified by the classification tree algorithm. The statistical characteristics of these features (i.e., maximum value, mean value, and variance) were calculated to quantify the difference between the dynamical cores and changing resolutions. Even with the simple and smoothmore » topography in the idealized setups, complexity in the precipitation fields simulated by the models develops quickly. The classification tree algorithm using objective thresholding successfully detected different types of precipitation features even as the complexity of the precipitation field increased. The results show that the complexity and the bias introduced in small-scale phenomena due to the spectral transform method of CAM Eulerian spectral dynamical core is prominent, and is an important reason for its dissimilarity from the FV dynamical core. The resolvable scales, both in horizontal and vertical dimensions, have significant effect on the simulation of precipitation. The results of this study also suggest that an efficient and informative study about the biases produced by GCMs should involve daily (or even hourly) output (rather than monthly mean) analysis over local scales.« less

A decision tree algorithm for investigation of model biases related to dynamical cores and physical parameterizations: CESM/CAM EVALUATION BY DECISION TREES

DOE PAGES

Soner Yorgun, M.; Rood, Richard B.

2016-11-11

An object-based evaluation method using a pattern recognition algorithm (i.e., classification trees) is applied to the simulated orographic precipitation for idealized experimental setups using the National Center of Atmospheric Research (NCAR) Community Atmosphere Model (CAM) with the finite volume (FV) and the Eulerian spectral transform dynamical cores with varying resolutions. Daily simulations were analyzed and three different types of precipitation features were identified by the classification tree algorithm. The statistical characteristics of these features (i.e., maximum value, mean value, and variance) were calculated to quantify the difference between the dynamical cores and changing resolutions. Even with the simple and smoothmore » topography in the idealized setups, complexity in the precipitation fields simulated by the models develops quickly. The classification tree algorithm using objective thresholding successfully detected different types of precipitation features even as the complexity of the precipitation field increased. The results show that the complexity and the bias introduced in small-scale phenomena due to the spectral transform method of CAM Eulerian spectral dynamical core is prominent, and is an important reason for its dissimilarity from the FV dynamical core. The resolvable scales, both in horizontal and vertical dimensions, have significant effect on the simulation of precipitation. The results of this study also suggest that an efficient and informative study about the biases produced by GCMs should involve daily (or even hourly) output (rather than monthly mean) analysis over local scales.« less

Development and Validation of HPLC Method for Determination of Crocetin, a constituent of Saffron, in Human Serum Samples.

PubMed

Mohammadpour, Amir Hooshang; Ramezani, Mohammad; Tavakoli Anaraki, Nasim; Malaekeh-Nikouei, Bizhan; Amel Farzad, Sara; Hosseinzadeh, Hossein

2013-01-01

The present study reports the development and validation of a sensitive and rapid extraction method beside high performance liquid chromatographic method for the determination of crocetin in human serum. The HPLC method was carried out by using a C18 reversed-phase column and a mobile phase composed of methanol/water/acetic acid (85:14.5:0.5 v/v/v) at the flow rate of 0.8 ml/min. The UV detector was set at 423 nm and 13-cis retinoic acid was used as the internal standard. Serum samples were pretreated with solid-phase extraction using Bond Elut C18 (200mg) cartridges or with direct precipitation using acetonitrile. The calibration curves were linear over the range of 0.05-1.25 µg/ml for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction. The mean recoveries of crocetin over a concentration range of 0.05-5 µg/ml serum for direct precipitation method and 0.5-5 µg/ml for solid-phase extraction were above 70 % and 60 %, respectively. The intraday coefficients of variation were 0.37- 2.6% for direct precipitation method and 0.64 - 5.43% for solid-phase extraction. The inter day coefficients of variation were 1.69 - 6.03% for direct precipitation method and 5.13-12.74% for solid-phase extraction, respectively. The lower limit of quantification for crocetin was 0.05 µg/ml for direct precipitation method and 0.5 µg/ml for solid-phase extraction. The validated direct precipitation method for HPLC satisfied all of the criteria that were necessary for a bioanalytical method and could reliably quantitate crocetin in human serum for future clinical pharmacokinetic study.

Germanium recovery from gasification fly ash: evaluation of end-products obtained by precipitation methods.

PubMed

Arroyo, Fátima; Font, Oriol; Fernández-Pereira, Constantino; Querol, Xavier; Juan, Roberto; Ruiz, Carmen; Coca, Pilar

2009-08-15

In this study the purity of the germanium end-products obtained by two different precipitation methods carried out on germanium-bearing solutions was evaluated as a last step of a hydrometallurgy process for the recovery of this valuable element from the Puertollano Integrated Gasification Combined Cycle (IGCC) fly ash. Since H(2)S is produced as a by-product in the gas cleaning system of the Puertollano IGCC plant, precipitation of germanium as GeS(2) was tested by sulfiding the Ge-bearing solutions. The technological and hazardous issues that surround H(2)S handling conducted to investigate a novel precipitation procedure: precipitation as an organic complex by adding 1,2-dihydroxy benzene pyrocatechol (CAT) and cetyltrimethylammonium bromide (CTAB) to the Ge-bearing solutions. Relatively high purity Ge end-products (90 and 93% hexagonal-GeO(2) purity, respectively) were obtained by precipitating Ge from enriched solutions, as GeS(2) sulfiding the solutions with H(2)S, or as organic complex with CAT/CTAB mixtures and subsequent roasting of the precipitates. Both methods showed high efficiency (>99%) to precipitate selectively Ge using a single precipitation stage from germanium-bearing solutions.

Implications of the methodological choices for hydrologic portrayals of climate change over the contiguous United States: Statistically downscaled forcing data and hydrologic models

USGS Publications Warehouse

Mizukami, Naoki; Clark, Martyn P.; Gutmann, Ethan D.; Mendoza, Pablo A.; Newman, Andrew J.; Nijssen, Bart; Livneh, Ben; Hay, Lauren E.; Arnold, Jeffrey R.; Brekke, Levi D.

2016-01-01

Continental-domain assessments of climate change impacts on water resources typically rely on statistically downscaled climate model outputs to force hydrologic models at a finer spatial resolution. This study examines the effects of four statistical downscaling methods [bias-corrected constructed analog (BCCA), bias-corrected spatial disaggregation applied at daily (BCSDd) and monthly scales (BCSDm), and asynchronous regression (AR)] on retrospective hydrologic simulations using three hydrologic models with their default parameters (the Community Land Model, version 4.0; the Variable Infiltration Capacity model, version 4.1.2; and the Precipitation–Runoff Modeling System, version 3.0.4) over the contiguous United States (CONUS). Biases of hydrologic simulations forced by statistically downscaled climate data relative to the simulation with observation-based gridded data are presented. Each statistical downscaling method produces different meteorological portrayals including precipitation amount, wet-day frequency, and the energy input (i.e., shortwave radiation), and their interplay affects estimations of precipitation partitioning between evapotranspiration and runoff, extreme runoff, and hydrologic states (i.e., snow and soil moisture). The analyses show that BCCA underestimates annual precipitation by as much as −250 mm, leading to unreasonable hydrologic portrayals over the CONUS for all models. Although the other three statistical downscaling methods produce a comparable precipitation bias ranging from −10 to 8 mm across the CONUS, BCSDd severely overestimates the wet-day fraction by up to 0.25, leading to different precipitation partitioning compared to the simulations with other downscaled data. Overall, the choice of downscaling method contributes to less spread in runoff estimates (by a factor of 1.5–3) than the choice of hydrologic model with use of the default parameters if BCCA is excluded.

Identification of relationships between climate indices and long-term precipitation in South Korea using ensemble empirical mode decomposition

NASA Astrophysics Data System (ADS)

Kim, Taereem; Shin, Ju-Young; Kim, Sunghun; Heo, Jun-Haeng

2018-02-01

Climate indices characterize climate systems and may identify important indicators for long-term precipitation, which are driven by climate interactions in atmosphere-ocean circulation. In this study, we investigated the climate indices that are effective indicators of long-term precipitation in South Korea, and examined their relationships based on statistical methods. Monthly total precipitation was collected from a total of 60 meteorological stations, and they were decomposed by ensemble empirical mode decomposition (EEMD) to identify the inherent oscillating patterns or cycles. Cross-correlation analysis and stepwise variable selection were employed to select the significant climate indices at each station. The climate indices that affect the monthly precipitation in South Korea were identified based on the selection frequencies of the selected indices at all stations. The NINO12 indices with four- and ten-month lags and AMO index with no lag were identified as indicators of monthly precipitation in South Korea. Moreover, they indicate meaningful physical information (e.g. periodic oscillations and long-term trend) inherent in the monthly precipitation. The NINO12 indices with four- and ten- month lags was a strong indicator representing periodic oscillations in monthly precipitation. In addition, the long-term trend of the monthly precipitation could be explained by the AMO index. A multiple linear regression model was constructed to investigate the influences of the identified climate indices on the prediction of monthly precipitation. Three identified climate indices successfully explained the monthly precipitation in the winter dry season. Compared to the monthly precipitation in coastal areas, the monthly precipitation in inland areas showed stronger correlation to the identified climate indices.

Self-organizing map network-based precipitation regionalization for the Tibetan Plateau and regional precipitation variability

NASA Astrophysics Data System (ADS)

Wang, Nini; Yin, Jianchuan

2017-12-01

A precipitation-based regionalization for the Tibetan Plateau (TP) was investigated for regional precipitation trend analysis and frequency analysis using data from 1113 grid points covering the period 1900-2014. The results utilizing self-organizing map (SOM) network suggest that four clusters of precipitation coherent zones can be identified, including the southwestern edge, the southern edge, the southeastern region, and the north central region. Regionalization results of the SOM network satisfactorily represent the influences of the atmospheric circulation systems such as the East Asian summer monsoon, the south Asian summer monsoon, and the mid-latitude westerlies. Regionalization results also well display the direct impacts of physical geographical features of the TP such as orography, topography, and land-sea distribution. Regional-scale annual precipitation trend as well as regional differences of annual and seasonal total precipitation were investigated by precipitation index such as precipitation concentration index (PCI) and Standardized Anomaly Index (SAI). Results demonstrate significant negative long-term linear trends in southeastern TP and the north central part of the TP, indicating arid and semi-arid regions in the TP are getting drier. The empirical mode decomposition (EMD) method shows an evolution of the main cycle with 4 and 12 months for all the representative grids of four sub-regions. The cross-wavelet analysis suggests that predominant and effective period of Indian Ocean Dipole (IOD) on monthly precipitation is around ˜12 months, except for the representative grid of the northwestern region.

Statistical simulation of ensembles of precipitation fields for data assimilation applications

NASA Astrophysics Data System (ADS)

Haese, Barbara; Hörning, Sebastian; Chwala, Christian; Bárdossy, András; Schalge, Bernd; Kunstmann, Harald

2017-04-01

The simulation of the hydrological cycle by models is an indispensable tool for a variety of environmental challenges such as climate prediction, water resources management, or flood forecasting. One of the crucial variables within the hydrological system, and accordingly one of the main drivers for terrestrial hydrological processes, is precipitation. A correct reproduction of the spatio-temporal distribution of precipitation is crucial for the quality and performance of hydrological applications. In our approach we stochastically generate precipitation fields conditioned on various precipitation observations. Rain gauges provide high-quality information for a specific measurement point, but their spatial representativeness is often rare. Microwave links, e. g. from commercial cellular operators, on the other hand can be used to estimate line integrals of near-surface rainfall information. They provide a very dense observational system compared to rain gauges. A further prevalent source of precipitation information are weather radars, which provide rainfall pattern informations. In our approach we derive precipitation fields, which are conditioned on combinations of these different observation types. As method to generate precipitation fields we use the random mixing method. Following this method a precipitation field is received as a linear combination of unconditional spatial random fields, where the spatial dependence structure is described by copulas. The weights of the linear combination are chosen in the way that the observations and the spatial structure of precipitation are reproduced. One main advantage of the random mixing method is the opportunity to consider linear and non-linear constraints. For a demonstration of the method we use virtual observations generated from a virtual reality of the Neckar catchment. These virtual observations mimic advantages and disadvantages of real observations. This virtual data set allows us to evaluate simulated precipitation fields in a very detailed manner as well as to quantify uncertainties which are conveyed by measurement inaccuracies. In a further step we use real observations as a basis for the generation of precipitation fields. The resulting ensembles of precipitation fields are used for example for data assimilation applications or as input data for hydrological models.

Precipitation of aluminum nitride in a high strength maraging steel with low nitrogen content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeanmaire, G., E-mail: guillaume.jeanmaire@univ-lorraine.fr; Aubert and Duval, BP1, 63770 Les Ancizes; Dehmas, M.

2014-12-15

In the present work, aluminum nitride (AlN) precipitation was investigated in a X23NiCoCrMoAl13-6-3 maraging steel with low nitrogen content (wt.% N = 5.5 ppm). A reliable and robust automatic method by scanning electron microscopy observations coupled with energy dispersive X-ray spectroscopy was developed for the quantification of AlN precipitates. The first stage was to identify the solvus temperature and to develop a heat treatment able to dissolve the AlN precipitates. The experimental determination of equilibrium conditions and solvus temperature show good agreement with ThermoCalc® simulation. Then, from this AlN-free state, the cooling rate, isothermal holding time and temperature were themore » subject of an intensive investigation in the austenite region of this maraging steel. In spite of the high temperatures used during heat treatments, the growth kinetic of the largest AlN precipitates (> 1 μm) is slow. The cooling rate has a major effect on the size and the number density of AlN due to a higher driving force for nucleation at low temperatures. At last, quenching prior to isothermal annealing at high temperatures leads to fine and dense AlN precipitation, resulting from the martensite to austenite transformation. Experimental results will be discussed and compared with kinetic data obtained with the mobility database MobFe2 implemented in Dictra® software. - Highlights: • Slow dissolution kinetic of AlN precipitates due to both their large size and small chemical driving force • Significant effects of cooling rate prior isothermal heat treatment, holding time and temperature on AlN precipitation • Size of AlN precipitates can be reduced by quenching prior isothermal holding. • Fine precipitation of AlN related to the α → γ transformation.« less

Effect of solution treatment on microstructure and properties of duplex stainless steel

NASA Astrophysics Data System (ADS)

Wang, X. Y.; Luo, J. M.; Huang, L. Q.; Wang, H. B.; Ma, C. W.

2017-09-01

The influence of solution treatment on microstructure and properties of 2205 duplex stainless steel (DSS) was studied. The microstructure, precipitates and corrosion resisting property were observed and analyzed by means of optical microscopy (OM), scanning electron microscopy (SEM) and electrochemical methods. The results showed that a large number of brittle σ-phase precipitates, which deteriorate the plasticity and corrosion resistance of the material, were easy to produce in the duplex stainless steel under the low temperature. The precipitation of σ-phase can be decreased and the plasticity and corrosion resistance can be improved by increasing solution temperature. In addition, the ferrite content increases with the increase of solution temperature, while less affected by cooling rate.

Three-dimensional characterization of BaHfO3 precipitates in GdBa2Cu3O7-y flim using STEM tomography.

PubMed

Nishiyama, T; Kaneko, K; Yamada, K; Teranishi, R; Kato, T; Hirayama, T; Tobita, H; Izumi, T; Shiohara, Y

2014-11-01

IntroductionSince the discovery of REBa2Cu3O7-y (RE: Rare Earth element, REBCO) superconductors, they have been expected as the best candidates for the power cable application due to its high critical temperature (Tc) and critical current density (Jc). Among those REBCO superconductors, GdBa2Cu3O7-y (GdBCO) have been receiving great interest because they have higher Tc and Jc than YBa2Cu3O7-y [1].GdBCO with various types of precipitates as artificial pinning centers (APCs) have been proposed to minimize the anisotropy of Jc characteristics under the magnetic field. Among those precipitates, BaHfO3 (BHO) was found most effective precipitates as APCs in GdBCO film prepared by pulsed laser deposition (PLD) method [2]. It is therefore necessary to investigate not only the morphologies but also the dispersion of BHO precipitates within the GdBCO, to understand the role of BHO for the superconducting characteristics. In this study, morphologies and dispersions of BHO precipitates were characterized three-dimensional by scanning transmission electron tomography ExperimentalBHO dispersed GdBCO films were fabricated on Hastelloy C-276TM substrates with buffer layers of CeO2/LaMnO3/MgO/ Gd2ZrO7 by PLD method.To observe microstructure of GdBCO film with BHO precipitates, cross-section TEM specimens were prepared by FIB method using Quanta 3D-200 (FEI, USA) with acceleration voltage from 2 to 30 kV. Three-dimensional information such as morphology and dispersion, of BHO precipitates were characterized by electron tomography using STEM-HAADF. Result and discussionFigure 1 shows three-dimensional reconstructed volume of BHO precipitates in GdBCO, which revealed that fine BHO precipitates have rod- and plate-like morphologies with homogeneous dispersion in GdBCO. In addition, growth directions of these precipitates were found with wide angular distributions from growth direction of GdBCO. Anisotropy of Jc in the magnetic fields was probably enhanced by various growth directions and homogeneous dispersion of nanosized BHO within GdBCO.jmicro;63/suppl_1/i26/DFU080F1F1DFU080F1Fig. 1.Three-dimensional reconstructed volume of BHO. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Plan and Some Results of "Advanced Study on Precipitation Enhancement in Arid and Semi-Arid Regions"

NASA Astrophysics Data System (ADS)

Murakami, M.

2016-12-01

There are several technologies to secure water resources, including the desalination of seawater, recycling of industrial water and reuse of wastewater. However precipitation enhancement is the only way we can create a large amount of water for industrial use, for example, water for irrigation, provided we find clouds suitable for cloud seeding and apply appropriate and effective methods to increase precipitation. Therefore, rain enhancement research is critical in the quest for new water security options and innovative solutions in the UAE and other arid and semi-arid regions. The main objective of our project is to better evaluate, and ultimately improve, the effectiveness of rain enhancement in the UAE and other arid and semi-arid regions using hygroscopic and glaciogenic seeding techniques. One of the major questions regarding rain enhancement today is the effectiveness of hygroscopic seeding for warm and supercooled convective clouds. Our research will investigate the microphysical processes in seeded and unseeded clouds using a combination of laboratory experiments, numerical simulations and in-situ aircraft measurements in order to decipher the mechanism responsible for precipitation augmentation due to hygroscopic seeding. In our research, major elements of cloud seeding, e.g., assessment of seedability, development of optimal seeding methods and evaluation of seeding effects, will be investigated in the most efficient and realistic way, within three years, using mainly the numerical models with the sophisticated seeding scheme, which is developed on a basis of laboratory experiments and then validated against in-situ and remote sensing observations. In addition to the research plan, the outcomes of the research projects, which will be made available to the public at the end of the project and benefit the broader society, is discussed.

Exploring the long-term balance between net precipitation and net groundwater exchange in Florida seepage lakes

USGS Publications Warehouse

Lee, Terrie M.; Sacks, Laura A.; Swancar, Amy

2014-01-01

The long-term balance between net precipitation and net groundwater exchange that maintains thousands of seepage lakes in Florida’s karst terrain is explored at a representative lake basin and then regionally for the State’s peninsular lake district. The 15-year water budget of Lake Starr includes El Niño Southern Oscillation (ENSO)-related extremes in rainfall, and provides the longest record of Bowen ratio energy-budget (BREB) lake evaporation and lake-groundwater exchanges in the southeastern United States. Negative net precipitation averaging -25 cm/yr at Lake Starr overturns the previously-held conclusion that lakes in this region receive surplus net precipitation. Net groundwater exchange with the lake was positive on average but too small to balance the net precipitation deficit. Groundwater pumping effects and surface-water withdrawals from the lake widened the imbalance. Satellite-based regional estimates of potential evapotranspiration at five large lakes in peninsular Florida compared well with basin-scale evaporation measurements from seven open-water sites that used BREB methods. The regional average lake evaporation estimated for Lake Starr during 1996-2011 was within 5 percent of its measured average, and regional net precipitation agreed within 10 percent. Regional net precipitation to lakes was negative throughout central peninsular Florida and the net precipitation deficit increased by about 20 cm from north to south. Results indicate that seepage lakes farther south on the peninsula receive greater net groundwater inflow than northern lakes and imply that northern lakes are in comparatively leakier hydrogeologic settings. Findings reveal the peninsular lake district to be more vulnerable than was previously realized to drier climate, surface-water withdrawals from lakes, and groundwater pumping effects.

Improving Satellite-Based Snowfall Estimation: A New Method for Classifying Precipitation Phase and Estimating Snowfall Rate

NASA Astrophysics Data System (ADS)

Sims, Elizabeth M.

In order to study the impact of climate change on the Earth's hydrologic cycle, global information about snowfall is needed. To achieve global measurements of snowfall over both land and ocean, satellites are necessary. While satellites provide the best option for making measurements on a global scale, the task of estimating snowfall rate from these measurements is a complex problem. Satellite-based radar, for example, measures effective radar reflectivity, Ze, which can be converted to snowfall rate, S, via a Ze-S relation. Choosing the appropriate Ze-S relation to apply is a complicated problem, however, because quantities such as particle shape, size distribution, and terminal velocity are often unknown, and these quantities directly affect the Ze-S relation. Additionally, it is important to correctly classify the phase of precipitation. A misclassification can result in order-of-magnitude errors in the estimated precipitation rate. Using global ground-based observations over multiple years, the influence of different geophysical parameters on precipitation phase is investigated, with the goal of obtaining an improved method for determining precipitation phase. The parameters studied are near-surface air temperature, atmospheric moisture, low-level vertical temperature lapse rate, surface skin temperature, surface pressure, and land cover type. To combine the effects of temperature and moisture, wet-bulb temperature, instead of air temperature, is used as a key parameter for separating solid and liquid precipitation. Results show that in addition to wet-bulb temperature, vertical temperature lapse rate also affects the precipitation phase. For example, at a near-surface wet-bulb temperature of 0°C, a lapse rate of 6°C km-1 results in an 86 percent conditional probability of solid precipitation, while a lapse rate of -2°C km-1 results in a 45 percent probability. For near-surface wet-bulb temperatures less than 0°C, skin temperature affects precipitation phase, although the effect appears to be minor. Results also show that surface pressure appears to influence precipitation phase in some cases, however, this dependence is not clear on a global scale. Land cover type does not appear to affect precipitation phase. Based on these findings, a parameterization scheme has been developed that accepts available meteorological data as input, and returns the conditional probability of solid precipitation. Ze-S relations for various particle shapes, size distributions, and terminal velocities have been developed as part of this research. These Ze-S relations have been applied to radar reflectivity data from the CloudSat Cloud Profiling Radar to calculate the annual mean snowfall rate. The calculated snowfall rates are then compared to surface observations of snowfall. An effort to determine which particle shape best represents the type of snow falling in various locations across the United States has been made. An optimized Ze-S relation has been developed, which combines multiple Ze-S relations in order to minimize error when compared to the surface snowfall observations. Additionally, the resulting surface snowfall rate is compared with the CloudSat standard product for snowfall rate.

Global Precipitation Measurement: Methods, Datasets and Applications

NASA Technical Reports Server (NTRS)

Tapiador, Francisco; Turk, Francis J.; Petersen, Walt; Hou, Arthur Y.; Garcia-Ortega, Eduardo; Machado, Luiz, A. T.; Angelis, Carlos F.; Salio, Paola; Kidd, Chris; Huffman, George J.;

Ammonia release method for depositing metal oxides

DOEpatents

Silver, Gary L.; Martin, Frank S.

1994-12-13

A method of depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates.

Quantitative measurement for the microstructural parameters of nano-precipitates in Al-Mg-Si-Cu alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Kai

Size, number density and volume fraction of nano-precipitates are important microstructural parameters controlling the strengthening of materials. In this work a widely accessible, convenient, moderately time efficient method with acceptable accuracy and precision has been provided for measurement of volume fraction of nano-precipitates in crystalline materials. The method is based on the traditional but highly accurate technique of measuring foil thickness via convergent beam electron diffraction. A new equation is proposed and verified with the aid of 3-dimensional atom probe (3DAP) analysis, to compensate for the additional error resulted from the hardly distinguishable contrast of too short incomplete precipitates cutmore » by the foil surface. The method can be performed on a regular foil specimen with a modern LaB{sub 6} or field-emission-gun transmission electron microscope. Precisions around ± 16% have been obtained for precipitate volume fractions of needle-like β″/C and Q precipitates in an aged Al-Mg-Si-Cu alloy. The measured number density is close to that directly obtained using 3DAP analysis by a misfit of 4.5%, and the estimated precision for number density measurement is about ± 11%. The limitations of the method are also discussed. - Highlights: •A facile method for measuring volume fraction of nano-precipitates based on CBED •An equation to compensate for small invisible precipitates, with 3DAP verification •Precisions around ± 16% for volume fraction and ± 11% for number density.« less

[Study on the determination of trace Cu and Mn in foodstuff preconcentration by precipitate flotation and FAAS].

PubMed

Li, Chun-xiang; Chen, Ting-yu; Yan, Yong-sheng

2007-10-01

In the present paper, the use of 8-hydroxyquinoline(oxine, HQ) complexs in precipitate flotation to separate and preconcentrate Cu and Mn, using SDBS as collector, followed by AAS spectrophotometric determination is proposed. The optimum conditions of precipitate flotation were studied. The effects of several parameters of flotation processes condition on single metal ions precipitation-flotation and multi-metal ions coprecipitation-flotation of Cu and Mn at pH 9 were investigated. The experimental results show that the flotation rate of Cu is supreme with pH 9. Under the condition of pH 9 and changing the ratio of concentration, when Mn/Cu> or =8, the recovery rate of Cu is less than 90%. This method is simple, rapid, accurate, sensitive and precise and avoids using the virulent organic solvent. The linear range of Cu is 0.5-5.0 microg x mL(-1) with the correlative coefficient of 0.9996, detection limit of this method was found to be 1.59 x 10(-3) microg x mL(-1), the linear range of Mn is 0.5-5.0 microg x mL(-1) with the correlative coefficient of 0.9987, and the detection limit of this method was found to be 3.52 x 10(-3) microg x mL(-1). The method was applied to the determination of Cu and Mn in foodstuff, and the recovery is 87.6%-100.7%. The result was satisfactory.

A precipitation regionalization and regime for Iran based on multivariate analysis

NASA Astrophysics Data System (ADS)

Raziei, Tayeb

2018-02-01

Monthly precipitation time series of 155 synoptic stations distributed over Iran, covering 1990-2014 time period, were used to identify areas with different precipitation time variability and regimes utilizing S-mode principal component analysis (PCA) and cluster analysis (CA) preceded by T-mode PCA, respectively. Taking into account the maximum loading values of the rotated components, the first approach revealed five sub-regions characterized by different precipitation time variability, while the second method delineated eight sub-regions featured with different precipitation regimes. The sub-regions identified by the two used methods, although partly overlapping, are different considering their areal extent and complement each other as they are useful for different purposes and applications. Northwestern Iran and the Caspian Sea area were found as the two most distinctive Iranian precipitation sub-regions considering both time variability and precipitation regime since they were well captured with relatively identical areas by the two used approaches. However, the areal extents of the other three sub-regions identified by the first approach were not coincident with the coverage of their counterpart sub-regions defined by the second approach. Results suggest that the precipitation sub-region identified by the two methods would not be necessarily the same, as the first method which accounts for the variance of the data grouped stations with similar temporal variability while the second one which considers a fixed climatology defined by the average over the period 1990-2014 clusters stations having a similar march of monthly precipitation.

Are recent severe floods in Xiang River basin of China linked with the increase extreme precipitation?

NASA Astrophysics Data System (ADS)

Cheng, L.; Du, J.

2015-12-01

The Xiang River, a main tributary of the Yangtze River, is subjected to high floods frequently in recent twenty years. Climate change, including abrupt shifts and fluctuations in precipitation is an important factor influencing hydrological extreme conditions. In addition, human activities are widely recognized as another reasons leading to high flood risk. With the effects of climate change and human interventions on hydrological cycle, there are several questions that need to be addressed. Are floods in the Xiang River basin getting worse? Whether the extreme streamflow shows an increasing tendency? If so, is it because the extreme rainfall events have predominant effect on floods? To answer these questions, the article detected existing trends in extreme precipitation and discharge using Mann-Kendall test. Continuous wavelet transform method was employed to identify the consistency of changes in extreme precipitation and discharge. The Pearson correlation analysis was applied to investigate how much degree of variations in extreme discharge can be explained by climate change. The results indicate that slightly upward trends can be detected in both extreme rainfalls and discharge in the upper region of Xiang River basin. For the most area of middle and lower river basin, the extreme rainfalls show significant positive trends, but the extreme discharge displays slightly upward trends with no significance at 90% confidence level. Wavelet transform analysis results illustrate that highly similar patterns of signal changes can be seen between extreme precipitation and discharge in upper section of the basin, while the changes in extreme precipitation for the middle and lower reaches do not always coincide with the extreme streamflow. The correlation coefficients of the wavelet transforms for the precipitation and discharge signals in most area of the basin pass the significance test. The conclusion may be drawn that floods in recent years are not getting worse in Xiang River basin. The similar signal patterns and positive correlation between extreme discharge and precipitation indicate that the variability of extreme precipitation has an important effect on extreme discharge of flood, although the intensity of human impacts in lower section of Xiang River basin has increased markedly.

Development of a global historic monthly mean precipitation dataset

NASA Astrophysics Data System (ADS)

Yang, Su; Xu, Wenhui; Xu, Yan; Li, Qingxiang

2016-04-01

Global historic precipitation dataset is the base for climate and water cycle research. There have been several global historic land surface precipitation datasets developed by international data centers such as the US National Climatic Data Center (NCDC), European Climate Assessment & Dataset project team, Met Office, etc., but so far there are no such datasets developed by any research institute in China. In addition, each dataset has its own focus of study region, and the existing global precipitation datasets only contain sparse observational stations over China, which may result in uncertainties in East Asian precipitation studies. In order to take into account comprehensive historic information, users might need to employ two or more datasets. However, the non-uniform data formats, data units, station IDs, and so on add extra difficulties for users to exploit these datasets. For this reason, a complete historic precipitation dataset that takes advantages of various datasets has been developed and produced in the National Meteorological Information Center of China. Precipitation observations from 12 sources are aggregated, and the data formats, data units, and station IDs are unified. Duplicated stations with the same ID are identified, with duplicated observations removed. Consistency test, correlation coefficient test, significance t-test at the 95% confidence level, and significance F-test at the 95% confidence level are conducted first to ensure the data reliability. Only those datasets that satisfy all the above four criteria are integrated to produce the China Meteorological Administration global precipitation (CGP) historic precipitation dataset version 1.0. It contains observations at 31 thousand stations with 1.87 × 107 data records, among which 4152 time series of precipitation are longer than 100 yr. This dataset plays a critical role in climate research due to its advantages in large data volume and high density of station network, compared to other datasets. Using the Penalized Maximal t-test method, significant inhomogeneity has been detected in historic precipitation datasets at 340 stations. The ratio method is then employed to effectively remove these remarkable change points. Global precipitation analysis based on CGP v1.0 shows that rainfall has been increasing during 1901-2013 with an increasing rate of 3.52 ± 0.5 mm (10 yr)-1, slightly higher than that in the NCDC data. Analysis also reveals distinguished long-term changing trends at different latitude zones.

Classification and global distribution of ocean precipitation types based on satellite passive microwave signatures

NASA Astrophysics Data System (ADS)

Gautam, Nitin

The main objectives of this thesis are to develop a robust statistical method for the classification of ocean precipitation based on physical properties to which the SSM/I is sensitive and to examine how these properties vary globally and seasonally. A two step approach is adopted for the classification of oceanic precipitation classes from multispectral SSM/I data: (1)we subjectively define precipitation classes using a priori information about the precipitating system and its possible distinct signature on SSM/I data such as scattering by ice particles aloft in the precipitating cloud, emission by liquid rain water below freezing level, the difference of polarization at 19 GHz-an indirect measure of optical depth, etc.; (2)we then develop an objective classification scheme which is found to reproduce the subjective classification with high accuracy. This hybrid strategy allows us to use the characteristics of the data to define and encode classes and helps retain the physical interpretation of classes. The classification methods based on k-nearest neighbor and neural network are developed to objectively classify six precipitation classes. It is found that the classification method based neural network yields high accuracy for all precipitation classes. An inversion method based on minimum variance approach was used to retrieve gross microphysical properties of these precipitation classes such as column integrated liquid water path, column integrated ice water path, and column integrated min water path. This classification method is then applied to 2 years (1991-92) of SSM/I data to examine and document the seasonal and global distribution of precipitation frequency corresponding to each of these objectively defined six classes. The characteristics of the distribution are found to be consistent with assumptions used in defining these six precipitation classes and also with well known climatological patterns of precipitation regions. The seasonal and global distribution of these six classes is also compared with the earlier results obtained from Comprehensive Ocean Atmosphere Data Sets (COADS). It is found that the gross pattern of the distributions obtained from SSM/I and COADS data match remarkably well with each other.

Bayesian Non-Stationary Index Gauge Modeling of Gridded Precipitation Extremes

NASA Astrophysics Data System (ADS)

Verdin, A.; Bracken, C.; Caldwell, J.; Balaji, R.; Funk, C. C.

2017-12-01

We propose a Bayesian non-stationary model to generate watershed scale gridded estimates of extreme precipitation return levels. The Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) dataset is used to obtain gridded seasonal precipitation extremes over the Taylor Park watershed in Colorado for the period 1981-2016. For each year, grid cells within the Taylor Park watershed are aggregated to a representative "index gauge," which is input to the model. Precipitation-frequency curves for the index gauge are estimated for each year, using climate variables with significant teleconnections as proxies. Such proxies enable short-term forecasting of extremes for the upcoming season. Disaggregation ratios of the index gauge to the grid cells within the watershed are computed for each year and preserved to translate the index gauge precipitation-frequency curve to gridded precipitation-frequency maps for select return periods. Gridded precipitation-frequency maps are of the same spatial resolution as CHIRPS (0.05° x 0.05°). We verify that the disaggregation method preserves spatial coherency of extremes in the Taylor Park watershed. Validation of the index gauge extreme precipitation-frequency method consists of ensuring extreme value statistics are preserved on a grid cell basis. To this end, a non-stationary extreme precipitation-frequency analysis is performed on each grid cell individually, and the resulting frequency curves are compared to those produced by the index gauge disaggregation method.

Precipitation forecast using artificial neural networks. An application to the Guadalupe Valley, Baja California, Mexico

NASA Astrophysics Data System (ADS)

Herrera-Oliva, C. S.

2013-05-01

In this work we design and implement a method for the determination of precipitation forecast through the application of an elementary neuronal network (perceptron) to the statistical analysis of the precipitation reported in catalogues. The method is limited mainly by the catalogue length (and, in a smaller degree, by its accuracy). The method performance is measured using grading functions that evaluate a tradeoff between positive and negative aspects of performance. The method is applied to the Guadalupe Valley, Baja California, Mexico. Using consecutive intervals of dt=0.1 year, employing the data of several climatological stations situated in and surrounding this important wine industries zone. We evaluated the performance of different models of ANN, whose variables of entrance are the heights of precipitation. The results obtained were satisfactory, except for exceptional values of rain. Key words: precipitation forecast, artificial neural networks, statistical analysis

Spatio-temporal interpolation of precipitation during monsoon periods in Pakistan

NASA Astrophysics Data System (ADS)

Hussain, Ijaz; Spöck, Gunter; Pilz, Jürgen; Yu, Hwa-Lung

2010-08-01

Spatio-temporal estimation of precipitation over a region is essential to the modeling of hydrologic processes for water resources management. The changes of magnitude and space-time heterogeneity of rainfall observations make space-time estimation of precipitation a challenging task. In this paper we propose a Box-Cox transformed hierarchical Bayesian multivariate spatio-temporal interpolation method for the skewed response variable. The proposed method is applied to estimate space-time monthly precipitation in the monsoon periods during 1974-2000, and 27-year monthly average precipitation data are obtained from 51 stations in Pakistan. The results of transformed hierarchical Bayesian multivariate spatio-temporal interpolation are compared to those of non-transformed hierarchical Bayesian interpolation by using cross-validation. The software developed by [11] is used for Bayesian non-stationary multivariate space-time interpolation. It is observed that the transformed hierarchical Bayesian method provides more accuracy than the non-transformed hierarchical Bayesian method.

Projections of East Asian summer monsoon change at global warming of 1.5 and 2 °C

NASA Astrophysics Data System (ADS)

Liu, Jiawei; Xu, Haiming; Deng, Jiechun

2018-04-01

Much research is needed regarding the two long-term warming targets of the 2015 Paris Agreement, i.e., 1.5 and 2 °C above pre-industrial levels, especially from a regional perspective. The East Asian summer monsoon (EASM) intensity change and associated precipitation change under both warming targets are explored in this study. The multimodel ensemble mean projections by 19 CMIP5 models show small increases in EASM intensity and general increases in summer precipitation at 1.5 and 2 °C warming, but with large multimodel standard deviations. Thus, a novel multimodel ensemble pattern regression (EPR) method is applied to give more reliable projections based on the concept of emergent constraints, which is effective at tightening the range of multimodel diversity and harmonize the changes of different variables over the EASM region. Future changes projected by using the EPR method suggest decreased precipitation over the Meiyu belt and increased precipitation over the high latitudes of East Asia and Central China, together with a considerable weakening of EASM intensity. Furthermore, reduced precipitation appears over 30-40° N of East Asia in June and over the Meiyu belt in July, with enhanced precipitation at their north and south sides. These changes in early summer are attributed to a southeastward retreat of the western North Pacific subtropical high (WNPSH) and a southward shift of the East Asian subtropical jet (EASJ), which weaken the moisture transport via southerly wind at low levels and alter vertical motions over the EASM region. In August, precipitation would increase over the high latitudes of East Asia with more moisture from the wetter area over the ocean in the east and decrease over Japan with westward extension of WNPSH. These monthly precipitation changes would finally contribute to a tripolar pattern of EASM precipitation change at 1.5 and 2 °C warming. Corrected EASM intensity exhibits a slight difference between 1.5 and 2 °C, but a pronounced moisture increase during extra 0.5 °C leads to enhanced EASM precipitation over large areas in East Asia at 2 °C warming.

Analysis of an ethanol precipitate from ileal digesta: evaluation of a method to determine mucin.

PubMed

Miner-Williams, Warren M; Moughan, Paul J; Fuller, Malcolm F

2013-11-06

The precipitation of mucin using high concentrations of ethanol has been used by many researchers while others have questioned the validity of the technique. In this study, analysis of an ethanol precipitate, from the soluble fraction of ileal digesta from pigs was undertaken using molecular weight profiling and polyacrylamide gel electrophoresis. The precipitate contained 201 mg·g⁻¹ protein, 87% of which had a molecular weight >20 KDa. Polyacrylamide gel electrophoresis stained with Coomassie blue and periodic acid/Schiff, revealed that most glycoprotein had a molecular weight between 37-100 KDa. The molecular weight of glycoprotein in the precipitate was therefore lower than that of intact mucin. These observations indicated that the glycoprotein in the ethanol precipitate was significantly degraded. The large amount of protein and carbohydrate in the supernatant from ethanol precipitation indicated that the precipitation of glycoprotein was incomplete. As a method for determining the concentration of mucin in digesta, ethanol precipitation is unreliable.

Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption.

NASA Astrophysics Data System (ADS)

Giannakoudakis, Dimitrios; Saroyan, Hayarpi; Lazaridis, Nikolaos; Deliyanni, Eleni

2016-04-01

Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption. Dimitrios Giannakoudakis1, Hayarpi Saroyan2, Nikolaos Lazaridis2, Eleni Deliyanni2 1 City College of New York, Chemistry Department, 160 Convent Avenue, New York, United States 2 Laboratory of General and oInorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece In this study, the effect of preparation route of a mesoporous magnetic activated carbon on Reactive Black 5 (RB5) adsorption was investigated. The synthesis of the magnetic activated carbon was achieved both with (i) impregnation method (Bmi), and (ii) co-precipitation with two precipitation agents: NaOH (Bm) and NH4OH (Bma). After synthesis, the full characterization with various techniques (SEM, FTIR, XRD, DTA, DTG, VSM) was achieved in order to testify the effect of the preparation route on its textural and surface properties. It was shown that after the precipitation method the prepared carbon presented a collapsed texture and small magnetic properties. Effects of initial solution pH, effect of temperature, adsorption isotherms and kinetics were investigated in order to conclude about the aforementioned effect of the preparation method on dye adsorption performance of the magnetic carbons. The adsorption evaluation of the magnetic activated carbon presented higher adsorption capacity of Bmi carbon (350 mg/g) and lower of Bm (150 mg/g). Equilibrium experiments are also performed studying the effect of contact time (pseudo-first and -second order equations) and temperature (isotherms at 25, 45 and 65 °C fitted to Langmuir and Freundlich model). A full thermodynamic evaluation was carried out, calculating the parameters of enthalpy, free energy and entropy (ΔHο, ΔGο and ΔSο). The characterization with various techniques revealed the possible interactions/forces of dye-composite system.

A quasi-in-situ EBSD observation of the transformation from rolling texture to recrystallization texture in V-4Cr-4Ti alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Lixia

Recrystallization texture evolution of rolled V-4Cr-4Ti alloy has been investigated by quasi-in-situ EBSD (electron back-scattering diffraction) method. Concurrently, the precipitates were characterized by SEM (Scanning Electron Microscopy). It was found that both the initial rolling textures and the distribution of the precipitates affected the formation of the recrystallization texture. It was revealed that the texture transformations of (558) 〈110〉 + (665) 〈110〉 to (334) 〈483〉 + (665) 〈1 1 2.4〉 were possibly attributed to the selective drag induced by the sparsely dispersed Ti-rich precipitates. While the densely distributed Ti-rich precipitates were responsible for the randomized recrystallization texture. Finally, when themore » precipitates were absent, the orientation changes from (112) 〈110〉 and (558) 〈110〉 to (111) 〈112〉 and (001) <110> to (001) <520> were observed. - Highlights: • Micro recrystallization texture evolution in V-4Cr-4Ti alloys is reported for the first time. • The volume fraction of Ti-rich precipitates has significant effect on the recrystallization texture evolution. • The dissolution of the Ti-rich precipitates above 1100 °C induces the strengthening of (111) <112> texture.« less

Monitoring bacterially induced calcite precipitation in porous media using magnetic resonance imaging and flow measurements

NASA Astrophysics Data System (ADS)

Sham, E.; Mantle, M. D.; Mitchell, J.; Tobler, D. J.; Phoenix, V. R.; Johns, M. L.

2013-09-01

A range of nuclear magnetic resonance (NMR) techniques are employed to provide novel, non-invasive measurements of both the structure and transport properties of porous media following a biologically mediated calcite precipitation reaction. Both a model glass bead pack and a sandstone rock core were considered. Structure was probed using magnetic resonance imaging (MRI) via a combination of quantitative one-dimensional profiles and three-dimensional images, applied before and after the formation of calcite in order to characterise the spatial distribution of the precipitate. It was shown through modification and variations of the calcite precipitation treatment that differences in the calcite fill would occur but all methods were successful in partially blocking the different porous media. Precipitation was seen to occur predominantly at the inlet of the bead pack, whereas precipitation occurred almost uniformly along the sandstone core. Transport properties are quantified using pulse field gradient (PFG) NMR measurements which provide probability distributions of molecular displacement over a set observation time (propagators), supplementing conventional permeability measurements. Propagators quantify the local effect of calcite formation on system hydrodynamics and the extent of stagnant region formation. Collectively, the combination of NMR measurements utilised here provides a toolkit for determining the efficacy of a biological-precipitation reaction for partially blocking porous materials.

The Association Between Extreme Precipitation and Waterborne Disease Outbreaks in the United States, 1948–1994

PubMed Central

Curriero, Frank C.; Patz, Jonathan A.; Rose, Joan B.; Lele, Subhash

2001-01-01

Objectives. Rainfall and runoff have been implicated in site-specific waterborne disease outbreaks. Because upward trends in heavy precipitation in the United States are projected to increase with climate change, this study sought to quantify the relationship between precipitation and disease outbreaks. Methods. The US Environmental Protection Agency waterborne disease database, totaling 548 reported outbreaks from 1948 through 1994, and precipitation data of the National Climatic Data Center were used to analyze the relationship between precipitation and waterborne diseases. Analyses were at the watershed level, stratified by groundwater and surface water contamination and controlled for effects due to season and hydrologic region. A Monte Carlo version of the Fisher exact test was used to test for statistical significance. Results. Fifty-one percent of waterborne disease outbreaks were preceded by precipitation events above the 90th percentile (P = .002), and 68% by events above the 80th percentile (P = .001). Outbreaks due to surface water contamination showed the strongest association with extreme precipitation during the month of the outbreak; a 2-month lag applied to groundwater contamination events. Conclusions. The statistically significant association found between rainfall and disease in the United States is important for water managers, public health officials, and risk assessors of future climate change. PMID:11499103

Radar-derived Quantitative Precipitation Estimation in Complex Terrain over the Eastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Gou, Y.

2017-12-01

Quantitative Precipitation Estimation (QPE) is one of the important applications of weather radars. However, in complex terrain such as Tibetan Plateau, it is a challenging task to obtain an optimal Z-R relation due to the complex space time variability in precipitation microphysics. This paper develops two radar QPE schemes respectively based on Reflectivity Threshold (RT) and Storm Cell Identification and Tracking (SCIT) algorithms using observations from 11 Doppler weather radars and 3294 rain gauges over the Eastern Tibetan Plateau (ETP). These two QPE methodologies are evaluated extensively using four precipitation events that are characterized by different meteorological features. Precipitation characteristics of independent storm cells associated with these four events, as well as the storm-scale differences, are investigated using short-term vertical profiles of reflectivity clusters. Evaluation results show that the SCIT-based rainfall approach performs better than the simple RT-based method in all precipitation events in terms of score comparison using validation gauge measurements as references, with higher correlation (than 75.74%), lower mean absolute error (than 82.38%) and root-mean-square error (than 89.04%) of all the comparative frames. It is also found that the SCIT-based approach can effectively mitigate the radar QPE local error and represent precipitation spatiotemporal variability better than RT-based scheme.

Sample preparation methods for scanning electron microscopy of homogenized Al-Mg-Si billets: A comparative study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Österreicher, Johannes Albert; Kumar, Manoj

Characterization of Mg-Si precipitates is crucial for optimizing the homogenization heat treatment of Al-Mg-Si alloys. Although sample preparation is key for high quality scanning electron microscopy imaging, most common methods lead to dealloying of Mg-Si precipitates. In this article we systematically evaluate different sample preparation methods: mechanical polishing, etching with various reagents, and electropolishing using different electrolytes. We demonstrate that the use of a nitric acid and methanol electrolyte for electropolishing a homogenized Al-Mg-Si alloy prevents the dissolution of Mg-Si precipitates, resulting in micrographs of higher quality. This preparation method is investigated in depth and the obtained scanning electron microscopymore » images are compared with transmission electron micrographs: the shape and size of Mg-Si precipitates appear very similar in either method. The scanning electron micrographs allow proper identification and measurement of the Mg-Si phases including needles with lengths of roughly 200 nm. These needles are β″ precipitates as confirmed by high resolution transmission electron microscopy. - Highlights: •Secondary precipitation in homogenized 6xxx Al alloys is crucial for extrudability. •Existing sample preparation methods for SEM are improvable. •Electropolishing with nitric acid/methanol yields superior quality in SEM. •The obtained micrographs are compared to TEM micrographs.« less

Precipitation data in a mountainous catchment in Honduras: quality assessment and spatiotemporal characteristics

NASA Astrophysics Data System (ADS)

Westerberg, I.; Walther, A.; Guerrero, J.-L.; Coello, Z.; Halldin, S.; Xu, C.-Y.; Chen, D.; Lundin, L.-C.

2010-08-01

An accurate description of temporal and spatial precipitation variability in Central America is important for local farming, water supply and flood management. Data quality problems and lack of consistent precipitation data impede hydrometeorological analysis in the 7,500 km2 Choluteca River basin in central Honduras, encompassing the capital Tegucigalpa. We used precipitation data from 60 daily and 13 monthly stations in 1913-2006 from five local authorities and NOAA's Global Historical Climatology Network. Quality control routines were developed to tackle the specific data quality problems. The quality-controlled data were characterised spatially and temporally, and compared with regional and larger-scale studies. Two gap-filling methods for daily data and three interpolation methods for monthly and mean annual precipitation were compared. The coefficient-of-correlation-weighting method provided the best results for gap-filling and the universal kriging method for spatial interpolation. In-homogeneity in the time series was the main quality problem, and 22% of the daily precipitation data were too poor to be used. Spatial autocorrelation for monthly precipitation was low during the dry season, and correlation increased markedly when data were temporally aggregated from a daily time scale to 4-5 days. The analysis manifested the high spatial and temporal variability caused by the diverse precipitation-generating mechanisms and the need for an improved monitoring network.

The Effects of El Niño on Precipitation in Southern California Climate Divisions: Year 2016 Precipitation Forecast.

NASA Astrophysics Data System (ADS)

Perez Cruz, L.; Idris, N.; El-Askary, H. M.

2015-12-01

Recently, it has been reported by the National Oceanic and Atmospheric Administration (NOAA) that there is very high chance not only for El Niño to continue through Northern Hemisphere winter 2015-16, but also a remarkable chance for El Niño to last into early spring 2016. This research aims at: 1) investigating the impact of El Niño on precipitation in the Southern California Climate Divisions: Climate Division 6 South Coast Drainage, and Division 7 South Coast Desert Basin. 2) Analyzing the precipitation of Southern California region using the Empirical Mode Decomposition Method (EMD). 3) Looking at the SOI components and compare it with the precipitation components of Southern California Climate Divisions. 4) Comparing precipitation data with Niño indices: Niño 1+2, Niño 3, Nino 3.4, and Niño 4. As results, we found a significant cross correlation of 0.7 between SOI component 10 and precipitation component 10 in Climate Division 6. Furthermore, among all the Niño indices, Niño 3 region displayed the best correlation. When we compared precipitation division 7 component 9 with Niño 3 component 10, a 0.95 cross correlation value was obtained. The lowest cross correlation value of (0.33) was obtained from Climate Division 6, precipitation component 7 with Niño 4 component 7.

An eco-friendly, quick and cost-effective method for the quantification of acrylamide in cereal-based baby foods.

PubMed

Cengiz, Mehmet Fatih; Gündüz, Cennet Pelin Boyacı

2014-09-01

The presence of acrylamide in cereal-based baby foods is a matter of great concern owing to its possible health effects. Derivatization followed by gas chromatography/mass spectrometry (GC/MS) is one of the most common methods to quantify acrylamide. However, it requires the use of toxic chemicals and is time-consuming. The aim of this study was to develop an eco-friendly, rapid and inexpensive method for the determination of acrylamide in cereal-based baby foods. The method involves defatting with n-hexane, extraction into water, precipitation of proteins, bromination, extraction into ethyl acetate and injection into a GC/MS system. The effects of defatting, precipitation, treatment with triethylamine, addition of internal standard and column selection were reviewed. A flow chart for acrylamide analysis was prepared. To evaluate the applicability of the method, 62 different cereal-based baby foods were analyzed. The levels of acrylamide ranged from not detected (below the limit of detection) to 660 µg kg(-1). The method is more eco-friendly and less expensive because it consumes very little solvent relative to other methods using bromine solutions and ethyl acetate. In addition, sample pre-treatment requires no solid phase extraction or concentration steps. The method is recommended for the determination of trace acrylamide in complex cereal-based baby food products. © 2014 Society of Chemical Industry.

Calibration of collection procedures for the determination of precipitation chemistry

Treesearch

James N. Galloway; Gene E. Likens

1976-01-01

Precipitation is currently collected by several methods, including several different designs of collection apparatus. We are investigating these differing methods and designs to determine which gives the most representative sample of precipitation for the analysis of some 25 chemical parameters. The experimental site, located in Ithaca, New York, has 22 collectors of...

Evaluation of the light scattering and the turbidity microtiter plate-based methods for the detection of the excipient-mediated drug precipitation inhibition.

PubMed

Petruševska, Marija; Urleb, Uroš; Peternel, Luka

2013-11-01

The excipient-mediated precipitation inhibition is classically determined by the quantification of the dissolved compound in the solution. In this study, two alternative approaches were evaluated, one is the light scattering (nephelometer) and other is the turbidity (plate reader) microtiter plate-based methods which are based on the quantification of the compound precipitate. Following the optimization of the nephelometer settings (beam focus, laser gain) and the experimental conditions, the screening of 23 excipients on the precipitation inhibition of poorly soluble fenofibrate and dipyridamole was performed. The light scattering method resulted in excellent correlation (r>0.91) between the calculated precipitation inhibitor parameters (PIPs) and the precipitation inhibition index (PI(classical)) obtained by the classical approach for fenofibrate and dipyridamole. Among the evaluated PIPs AUC100 (nephelometer) resulted in only four false positives and lack of false negatives. In the case of the turbidity-based method a good correlation of the PI(classical) was obtained for the PIP maximal optical density (OD(max), r=0.91), however, only for fenofibrate. In the case of the OD(max) (plate reader) five false positives and two false negatives were identified. In conclusion, the light scattering-based method outperformed the turbidity-based one and could be reliably used for identification of novel precipitation inhibitors. Copyright © 2013 Elsevier B.V. All rights reserved.

Ultrasonic recovery of copper and iron through the simultaneous utilization of Printed Circuit Boards (PCB) spent acid etching solution and PCB waste sludge.

PubMed

Huang, Zhiyuan; Xie, Fengchun; Ma, Yang

2011-01-15

A method was developed to recover the copper and iron from Printed Circuit Boards (PCB) manufacturing generated spent acid etching solution and waste sludge with ultrasonic energy at laboratory scale. It demonstrated that copper-containing PCB spent etching solution could be utilized as a leaching solution to leach copper from copper contained PCB waste sludge. It also indicated that lime could be used as an alkaline precipitating agent in this method to precipitate iron from the mixture of acidic PCB spent etching solution and waste sludge. This method provided an effective technique for the recovery of copper and iron through simultaneous use of PCB spent acid solution and waste sludge. The leaching rates of copper and iron enhanced with ultrasound energy were reached at 93.76% and 2.07% respectively and effectively separated copper from iron. Followed by applying lime to precipitate copper from the mixture of leachate and rinsing water produced by the copper and iron separation, about 99.99% and 1.29% of soluble copper and calcium were settled as the solids respectively. Furthermore the settled copper could be made as commercial rate copper. The process performance parameters studied were pH, ultrasonic power, and temperature. This method provided a simple and reliable technique to recover copper and iron from waste streams generated by PCB manufacturing, and would significantly reduce the cost of chemicals used in the recovery. Copyright © 2010 Elsevier B.V. All rights reserved.

Magnetic agglomeration method for size control in the synthesis of magnetic nanoparticles

DOEpatents

Huber, Dale L [Albuquerque, NM

2011-07-05

A method for controlling the size of chemically synthesized magnetic nanoparticles that employs magnetic interaction between particles to control particle size and does not rely on conventional kinetic control of the reaction to control particle size. The particles are caused to reversibly agglomerate and precipitate from solution; the size at which this occurs can be well controlled to provide a very narrow particle size distribution. The size of particles is controllable by the size of the surfactant employed in the process; controlling the size of the surfactant allows magnetic control of the agglomeration and precipitation processes. Agglomeration is used to effectively stop particle growth to provide a very narrow range of particle sizes.

genRE: A Method to Extend Gridded Precipitation Climatology Data Sets in Near Real-Time for Hydrological Forecasting Purposes

NASA Astrophysics Data System (ADS)

van Osnabrugge, B.; Weerts, A. H.; Uijlenhoet, R.

2017-11-01

To enable operational flood forecasting and drought monitoring, reliable and consistent methods for precipitation interpolation are needed. Such methods need to deal with the deficiencies of sparse operational real-time data compared to quality-controlled offline data sources used in historical analyses. In particular, often only a fraction of the measurement network reports in near real-time. For this purpose, we present an interpolation method, generalized REGNIE (genRE), which makes use of climatological monthly background grids derived from existing gridded precipitation climatology data sets. We show how genRE can be used to mimic and extend climatological precipitation data sets in near real-time using (sparse) real-time measurement networks in the Rhine basin upstream of the Netherlands (approximately 160,000 km2). In the process, we create a 1.2 × 1.2 km transnational gridded hourly precipitation data set for the Rhine basin. Precipitation gauge data are collected, spatially interpolated for the period 1996-2015 with genRE and inverse-distance squared weighting (IDW), and then evaluated on the yearly and daily time scale against the HYRAS and EOBS climatological data sets. Hourly fields are compared qualitatively with RADOLAN radar-based precipitation estimates. Two sources of uncertainty are evaluated: station density and the impact of different background grids (HYRAS versus EOBS). The results show that the genRE method successfully mimics climatological precipitation data sets (HYRAS/EOBS) over daily, monthly, and yearly time frames. We conclude that genRE is a good interpolation method of choice for real-time operational use. genRE has the largest added value over IDW for cases with a low real-time station density and a high-resolution background grid.

Climate change effects on extreme flows of water supply area in Istanbul: utility of regional climate models and downscaling method.

PubMed

Kara, Fatih; Yucel, Ismail

2015-09-01

This study investigates the climate change impact on the changes of mean and extreme flows under current and future climate conditions in the Omerli Basin of Istanbul, Turkey. The 15 regional climate model output from the EU-ENSEMBLES project and a downscaling method based on local implications from geophysical variables were used for the comparative analyses. Automated calibration algorithm is used to optimize the parameters of Hydrologiska Byråns Vattenbalansavdel-ning (HBV) model for the study catchment using observed daily temperature and precipitation. The calibrated HBV model was implemented to simulate daily flows using precipitation and temperature data from climate models with and without downscaling method for reference (1960-1990) and scenario (2071-2100) periods. Flood indices were derived from daily flows, and their changes throughout the four seasons and year were evaluated by comparing their values derived from simulations corresponding to the current and future climate. All climate models strongly underestimate precipitation while downscaling improves their underestimation feature particularly for extreme events. Depending on precipitation input from climate models with and without downscaling the HBV also significantly underestimates daily mean and extreme flows through all seasons. However, this underestimation feature is importantly improved for all seasons especially for spring and winter through the use of downscaled inputs. Changes in extreme flows from reference to future increased for the winter and spring and decreased for the fall and summer seasons. These changes were more significant with downscaling inputs. With respect to current time, higher flow magnitudes for given return periods will be experienced in the future and hence, in the planning of the Omerli reservoir, the effective storage and water use should be sustained.

The effect of organic ligands on the crystallinity of calcium phosphate

NASA Astrophysics Data System (ADS)

van der Houwen, Jacqueline A. M.; Cressey, Gordon; Cressey, Barbara A.; Valsami-Jones, Eugenia

2003-03-01

Calcium phosphate phases precipitated under critical supersaturation were identified and studied in detail using X-ray powder diffraction, electron probe microanalysis, infrared spectroscopy (IR) and transmission electron microscopy. These synthetic calcium phosphates formed by spontaneous precipitation at pH 7, 25°C and 0.1 M ionic strength (NaCl as the background electrolyte). The combination of several methods allowed detailed characterisation of the calcium phosphates. The purpose of the work was to assess the influence of carboxylate ligands, specifically acetate and citrate, on the quality of the calcium phosphate precipitate. All precipitates were identified as non-stoichiometric, calcium-deficient hydroxylapatites (HAPs), containing carbonate, HPO 42-, sodium and chloride impurities. No other phases were found to be present in any of the precipitates. The presence of citrate resulted in a decrease in crystal size and a higher degree of apatite lattice imperfection in the precipitated HAP. Furthermore, IR spectroscopy showed a higher amount of carbonate present in that HAP, compared with the ones formed in the control and acetate experiments. An additional absorption band, in the infrared spectrum of the HAP formed in the presence of citrate, was observed at 1570 cm -1; this is interpreted as carboxyl groups bound to HAP.

Preparation and evaluation of ageing effect of Cu-Al-Be-Mn shape memory alloys

NASA Astrophysics Data System (ADS)

Shivasiddaramaiah, A. G.; Mallik, U. S.; Mahato, Ranjit; Shashishekar, C.

2018-04-01

10-14 wt. % of aluminum, 0.3-0.6 wt. % of beryllium and 0.1-0.4 wt. % of manganese and remaining copper melted in the induction furnace through ingot metallurgy. The prepared SMAs are subjected to homogenization. It was observed that the samples exhibits β-phase at high temperature and shape memory effect after going through step quenching to a low temperature. Scanning Electron Microscope, DSC, bending test were performed on the samples to determine the microstructure, transformation temperatures and shape memory effect respectively. The alloy exhibit good shape memory effect, up to around 96% strain recovery by shape memory effect. The ageing is performed on the specimen prepared according to ASTM standard for testing micro-hardness and tensile test. Precipitation hardening method was employed to age the samples and they were aged at different temperature and at different times followed by quenching. Various forms of precipitates were formed. It was found that the formation rate and transformation temperature increased with ageing time, while the amount of precipitate had an inverse impact on strain recovery by shape memory effect. The result expected is to increase in mechanical properties of the material such as hardness.

Reorganization of river networks under changing spatiotemporal precipitation patterns: An optimal channel network approach

NASA Astrophysics Data System (ADS)

Abed-Elmdoust, Armaghan; Miri, Mohammad-Ali; Singh, Arvind

2016-11-01

We investigate the impact of changing nonuniform spatial and temporal precipitation patterns on the evolution of river networks. To achieve this, we develop a two-dimensional optimal channel network (OCN) model with a controllable rainfall distribution to simulate the evolution of river networks, governed by the principle of minimum energy expenditure, inside a prescribed boundary. We show that under nonuniform precipitation conditions, river networks reorganize significantly toward new patterns with different geomorphic and hydrologic signatures. This reorganization is mainly observed in the form of migration of channels of different orders, widening or elongation of basins as well as formation and extinction of channels and basins. In particular, when the precipitation gradient is locally increased, the higher-order channels, including the mainstream river, migrate toward regions with higher precipitation intensity. Through pertinent examples, the reorganization of the drainage network is quantified via stream parameters such as Horton-Strahler and Tokunaga measures, order-based channel total length and river long profiles obtained via simulation of three-dimensional basin topography, while the hydrologic response of the evolved network is investigated using metrics such as hydrograph and power spectral density of simulated streamflows at the outlet of the network. In addition, using OCNs, we investigate the effect of orographic precipitation patterns on multicatchment landscapes composed of several interacting basins. Our results show that network-inspired methods can be utilized as insightful and versatile models for directly exploring the effects of climate change on the evolution of river drainage systems.

Effect of nano/micro-Ag compound particles on the bio-corrosion, antibacterial properties and cell biocompatibility of Ti-Ag alloys.

PubMed

Chen, Mian; Yang, Lei; Zhang, Lan; Han, Yong; Lu, Zheng; Qin, Gaowu; Zhang, Erlin

2017-06-01

In this research, Ti-Ag alloys were prepared by powder metallurgy, casting and heat treatment method in order to investigate the effect of Ag compound particles on the bio-corrosion, the antibacterial property and the cell biocompatibility. Ti-Ag alloys with different sizes of Ag or Ag-compounds particles were successfully prepared: small amount of submicro-scale (100nm) Ti 2 Ag precipitates with solid solution state of Ag, large amount of nano-scale (20-30nm) Ti 2 Ag precipitates with small amount of solid solution state of Ag and micro-scale lamellar Ti 2 Ag phases, and complete solid solution state of Ag. The mechanical tests indicated that both nano/micro-scale Ti 2 Ag phases had a strong dispersion strengthening ability and Ag had a high solid solution strengthening ability. Electrochemical results shown the Ag content and the size of Ag particles had a limited influence on the bio-corrosion resistance although nano-scale Ti 2 Ag precipitates slightly improved corrosion resistance. It was demonstrated that the nano Ag compounds precipitates have a significant influence on the antibacterial properties of Ti-Ag alloys but no effect on the cell biocompatibility. It was thought that both Ag ions release and Ti 2 Ag precipitates contributed to the antibacterial ability, in which nano-scale and homogeneously distributed Ti 2 Ag phases would play a key role in antibacterial process. Copyright © 2017 Elsevier B.V. All rights reserved.

Barrier Effect of the Indo-Pacific Maritime Continent on the MJO: Perspectives from Tracking MJO Precipitation

NASA Astrophysics Data System (ADS)

Zhang, C.; Ling, J.

2016-12-01

To advance the study of the barrier effect of the Indo-Pacific Maritime Continent (MC) on the MJO, we propose two criteria to judge explanations for this phenomenon. The first one is that such explanations should include specific features of the MC, namely, its intricate land-sea distributions and elevated terrains. The second is that they should include mechanisms for some MJO events to overcome the barrier effect as well as the barrier effect itself. Guided by these criteria, we have used a precipitation-tracking method to identify MJO events, distinguish those that propagate across the MC (MJO-C) from those that are blocked by the MC (MJO-B), and compare these two types of MJO events and their large-scale environments. The barrier effect cannot be explained in terms of the strength and horizontal scale or distributions of MJO convection as it approaches the MC from the Indian Ocean. A distinction between MJO-B and MJO-C is their ratios of precipitation over the sea vs. land in the MC. MJO events may propagate through the MC when their convection over the sea of the MC is sufficiently developed and dominates that over land. This may happen for two reasons. One is stronger precipitation over land that occurs before the arrival of MJO convection centers, which is assisted by greater low-level moisture flux convergence over the MC. This stronger "vanguard of precipitation" for MJO-C would make the ground wetter and thus reduce land-locked diurnal convection that has been proposed to be detrimental to MJO propagation through the MC. Another possible reason for the more vigorous development of MJO-C convection over the sea is higher SST in the MC before MJO convection centers enter the region.

Cross-evaluation of ground-based, multi-satellite and reanalysis precipitation products: Applicability of the Triple Collocation method across Mainland China

NASA Astrophysics Data System (ADS)

Li, Changming; Tang, Guoqiang; Hong, Yang

2018-07-01

Evaluating the reliability of satellite and reanalysis precipitation products is critical but challenging over ungauged or poorly gauged regions. The Triple Collocation (TC) method is a reliable approach to estimate the accuracy of any three independent inputs in the absence of truth values. This study assesses the uncertainty of three types of independent precipitation products, i.e., satellite-based, ground-based and model reanalysis over Mainland China using the TC method. The ground-based data set is Gauge Based Daily Precipitation Analysis (CGDPA). The reanalysis data set is European Reanalysis Agency Reanalysis Product (ERA-interim). The satellite-based products include five mainstream satellite products. The comparison and evaluation are conducted at 0.25° and daily resolutions from 2013 to 2015. First, the effectiveness of the TC method is evaluated in South China with dense gauge network. The results demonstrate that the TC method is reliable because the correlation coefficient (CC) and root mean square error (RMSE) derived from TC are close to those derived from ground observations, with only 9% and 7% mean relative differences, respectively. Then, the TC method is applied in Mainland China, with special attention paid to the Tibetan Plateau (TP) known as the Earth's third pole with few ground stations. Results indicate that (1) The overall performance of IMERG is better than the other satellite products over Mainland China, followed by 3B42V7, CMORPH-CRT and PERSIANN-CDR. (2) In the TP, CGDPA shows the best overall performance over gauged grid cells, however, over ungauged regions, IMERG and ERA-interim slightly outperform CGDPA with similar RMSE but higher mean CC (0.63, 0.61, and 0.58, respectively). It highlights the strengths and potentiality of remote sensing and reanalysis data over the TP and reconfirms the cons of the inherent uncertainty of CGDPA due to interpolation from sparsely gauged data. The study concludes that the TC method provides not only reliable cross-validation results over Mainland China but also a new perspective for comparatively assessing multi-source precipitation products, particularly over poorly gauged regions such as the TP.

Characterizing hydroclimatic variability in tributaries of the Upper Colorado River Basin—WY1911-2001

NASA Astrophysics Data System (ADS)

Matter, Margaret A.; Garcia, Luis A.; Fontane, Darrell G.; Bledsoe, Brian

2010-01-01

SummaryMountain snowpack is the main source of water in the semi-arid Colorado River Basin (CRB), and while the demands for water are increasing, competing and often conflicting, the supply is limited and has become increasingly variable over the 20th Century. Greater variability is believed to contribute to lower accuracy in water supply forecasts, plus greater variability violates the assumption of stationarity, a fundamental assumption of many methods used in water resources engineering planning, design and management. Thus, it is essential to understand the underpinnings of hydroclimatic variability in order to accurately predict effects of climate changes and effectively meet future water supply challenges. A new methodology was applied to characterized time series of temperature, precipitation, and streamflow (i.e., historic and reconstructed undepleted flows) according to the three climate regimes that occurred in CRB during the 20th Century. Results for two tributaries in the Upper CRB show that hydroclimatic variability is more deterministic than previously thought because it entails complementary temperature and precipitation patterns associated with wetter or drier conditions on climate regime and annual scales. Complementary temperature and precipitation patterns characterize climate regime type (e.g., cool/wet and warm/dry), and the patterns entail increasing or decreasing temperatures and changes in magnitude and timing of precipitation according to the climate regime type. Accompanying each climate regime on annual scales are complementary temperature ( T) and precipitation ( P) patterns that are associated with upcoming precipitation and annual basin yield (i.e., total annual flow volume at a streamflow gauge). Annual complementary T and P patterns establish by fall, are detectable as early as September, persist to early spring, are related to the relative magnitude of upcoming precipitation and annual basin yield, are unique to climate regime type, and are specific to each river basin. Thus, while most of the water supply in the Upper CRB originates from winter snowpack, statistically significant indictors of relative magnitude of upcoming precipitation and runoff are evident in the fall, well before appreciable snow accumulation. Results of this study suggest strategies that may integrated into existing forecast methods to potentially improve forecast accuracy and advance lead time by as much as six months (i.e., from April 1 to October 1 of the previous year). These techniques also have applications in downscaling climate models and in river restoration and management.

Identification and root cause analysis of cell culture media precipitates in the viral deactivation treatment with high-temperature/short-time method.

PubMed

Cao, Xiaolin; Stimpfl, Gregory; Wen, Zai-Qing; Frank, Gregory; Hunter, Glenn

2013-01-01

High-temperature/short-time (HTST) treatment of cell culture media is one of the proven techniques used in the biopharmaceutical manufacturing industry for the prevention and mitigation of media viral contamination. With the HTST method, the formulated media is pasteurized (virus-deactivated) by heating and pumping the media continuously through the preset high-temperature holding tubes to achieve a specified period of time at a specific temperature. Recently, during the evaluation and implementation of HTST method in multiple Amgen, Inc. manufacturing facilities, media precipitates were observed in the tests of HTST treatments. The media precipitates may have adverse consequences such as clogging the HTST system, altering operating conditions and compromising the efficacy of viral deactivation, and ultimately affecting the media composition and cell growth. In this study, we report the identification of the composition of media precipitates from multiple media HTST runs using combined microspectroscopic methods including Raman, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The major composition in the precipitates was determined to be metal phosphates, including calcium phosphate, magnesium phosphate, and iron (III) phosphate. Based on the composition, stoichiometry, and root-cause study of media precipitations, methods were implemented for the mitigation and prevention of the occurrence of the media precipitation. Viral contamination in cell culture media is an important issue in the biopharmaceutical manufacturing industry and may have serious consequences on product quality, efficacy, and safety. High-temperature/short-time (HTST) treatment of cell culture media is one of the proven techniques used in the industry for the prevention and mitigation of media viral contamination. With the HTST method, the formulated media is pasteurized (virus-deactivated) by heating at preset conditions. This paper provides the identification and root-cause study of the media precipitates that adversely affected the HTST process and discusses the possible solutions to mitigate the precipitation problem.

Multiresolution comparison of precipitation datasets for large-scale models

NASA Astrophysics Data System (ADS)

Chun, K. P.; Sapriza Azuri, G.; Davison, B.; DeBeer, C. M.; Wheater, H. S.

2014-12-01

Gridded precipitation datasets are crucial for driving large-scale models which are related to weather forecast and climate research. However, the quality of precipitation products is usually validated individually. Comparisons between gridded precipitation products along with ground observations provide another avenue for investigating how the precipitation uncertainty would affect the performance of large-scale models. In this study, using data from a set of precipitation gauges over British Columbia and Alberta, we evaluate several widely used North America gridded products including the Canadian Gridded Precipitation Anomalies (CANGRD), the National Center for Environmental Prediction (NCEP) reanalysis, the Water and Global Change (WATCH) project, the thin plate spline smoothing algorithms (ANUSPLIN) and Canadian Precipitation Analysis (CaPA). Based on verification criteria for various temporal and spatial scales, results provide an assessment of possible applications for various precipitation datasets. For long-term climate variation studies (~100 years), CANGRD, NCEP, WATCH and ANUSPLIN have different comparative advantages in terms of their resolution and accuracy. For synoptic and mesoscale precipitation patterns, CaPA provides appealing performance of spatial coherence. In addition to the products comparison, various downscaling methods are also surveyed to explore new verification and bias-reduction methods for improving gridded precipitation outputs for large-scale models.

An effective placental cotyledons proteins extraction method for 2D gel electrophoresis.

PubMed

Tan, Niu J; Daim, Leona D J; Jamil, Amilia A M; Mohtarrudin, Norhafizah; Thilakavathy, Karuppiah

2017-03-01

Effective protein extraction is essential especially in producing a well-resolved proteome on 2D gels. A well-resolved placental cotyledon proteome, with good reproducibility, have allowed researchers to study the proteins underlying the physiology and pathophysiology of pregnancy. The aim of this study is to determine the best protein extraction protocol for the extraction of protein from placental cotyledons tissues for a two-dimensional gel electrophoresis (2D-GE). Based on widely used protein extraction strategies, 12 different extraction methodologies were carefully selected, which included one chemical extraction, two mechanical extraction coupled protein precipitations, and nine chemical extraction coupled protein precipitations. Extracted proteins were resolved in a one-dimensional gel electrophoresis and 2D-GE; then, it was compared with set criteria: extraction efficacy, protein resolution, reproducibility, and recovery efficiency. Our results revealed that a better profile was obtained by chemical extraction in comparison to mechanical extraction. We further compared chemical extraction coupled protein precipitation methodologies, where the DNase/lithium chloride-dense sucrose homogenization coupled dichloromethane-methanol precipitation (DNase/LiCl-DSH-D/MPE) method showed good protein extraction efficiency. This, however, was carried out with the best protein resolution and proteome reproducibility on 2D-gels. DNase/LiCl-DSH-D/MPE was efficient in the extraction of proteins from placental cotyledons tissues. In addition, this methodology could hypothetically allow the protein extraction of any tissue that contains highly abundant lipid and glycogen. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of processing route for preparation of mullite from kaolinite and alumina

NASA Astrophysics Data System (ADS)

Behera, Pallavi Suhasinee; Bhattacharyya, Sunipa

2018-05-01

In current work, two different types of mullite ceramic powder were prepared using kaolinite and alumina by solid state and chemical precipitation route. The phases, bond types and microstructural evolution of the mullite powders were investigated by X-ray diffraction, infrared analysis, and field emission scanning electron microscopy to study the mullitisation behavior. The solid state method evident a pure mullite phase formation at 1550 °C. In case of chemical precipitation route small amount of alumina peak was noticed along with major phase of mullite which was also clearly apprehended from FESEM micrographs and IR spectra. Densification was more for the samples prepared by solid state process which may be correlated to the delayed mullitization process in chemical precipitation route.

Effects of Precipitant and pH on Coprecipitation of Nanosized Co-Cr-V Alloy Powders

PubMed Central

Chen, Xiaoyu; Li, Yongxia; Huang, Lan; Zou, Dan; Wu, Enxi; Liu, Yanjun; Xie, Yuanyan; Yao, Rui; Liao, Songyi; Wang, Guangrong

2017-01-01

Nanosized Co-Cr-V alloy powders were synthesized via coprecipitation method. Effects of precipitants ((NH4)2C2O4·H2O and Na2CO3) and pH were investigated by X-ray diffraction (XRD), Zeta potential analyzer, thermogravimetry-differential scanning calorimetry (TG-DSC), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). Co-Cr-V alloy powders were consisted of major face-centered cubic Co (fcc Co) and minor hexagonal close-packed Co (hcp Co). Grain sizes of precursors and Co-Cr-V alloy powders were increased with pH value (7–10) within the ranges of 3~39 and 39~66 nm, respectively. Rod-like or granular Co-Cr-V alloy particles were assembled by interconnected nanograins. At pH = 7, Na2CO3 precipitant was found to be beneficial to maintain the desirable composition of Co-Cr-V powders. It was also found that lower pH favors the maintenance of pre-designed composition, while grain coarsens at higher pH. Effects of variation for precipitant and pH on the morphology and composition of Co-Cr-V alloy powder were discussed in detail and relevant mechanism was further proposed. PMID:28934147

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffin, Brian M.; Larson, Vincent E.

Microphysical processes, such as the formation, growth, and evaporation of precipitation, interact with variability and covariances (e.g., fluxes) in moisture and heat content. For instance, evaporation of rain may produce cold pools, which in turn may trigger fresh convection and precipitation. These effects are usually omitted or else crudely parameterized at subgrid scales in weather and climate models.A more formal approach is pursued here, based on predictive, horizontally averaged equations for the variances, covariances, and fluxes of moisture and heat content. These higher-order moment equations contain microphysical source terms. The microphysics terms can be integrated analytically, given a suitably simplemore » warm-rain microphysics scheme and an approximate assumption about the multivariate distribution of cloud-related and precipitation-related variables. Performing the integrations provides exact expressions within an idealized context.A large-eddy simulation (LES) of a shallow precipitating cumulus case is performed here, and it indicates that the microphysical effects on (co)variances and fluxes can be large. In some budgets and altitude ranges, they are dominant terms. The analytic expressions for the integrals are implemented in a single-column, higher-order closure model. Interactive single-column simulations agree qualitatively with the LES. The analytic integrations form a parameterization of microphysical effects in their own right, and they also serve as benchmark solutions that can be compared to non-analytic integration methods.« less

Ammonia release method for depositing metal oxides

DOEpatents

Silver, G.L.; Martin, F.S.

1994-12-13

A method is described for depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates. 1 figure.

Development of Microalloyed Steels for The Oil and Gas Industry

NASA Astrophysics Data System (ADS)

Henein, H.; Ivey, D. G.; Luo, J.; Wiskel, J. B.

Microalloying, in combination with thermomechanical controlled processing (TMCP), is a cost effective method of producing steels for a wide range of applications where improved mechanical properties, namel y strength, formability and toughness coupled with weldability, are required. This paper reviews the efforts undertaken at the University of Alberta aimed at improving the above mentioned mechanical properties in microalloyed steels used in the transmission of oil and gas (i.e., pipelines). Topics that will be reviewed include the characterization of precipitates, the effect of processing conditions on precipitate evolution, and the effect of pipe forming and subsequent low temperature heat treatment on tensile behaviour and the use of Genetic Algorithm optimization of the laminar cooling system to produce a uniform through thickness microstructure.

A simple and rapid method to isolate purer M13 phage by isoelectric precipitation.

PubMed

Dong, Dexian; Sutaria, Sanjana; Hwangbo, Je Yeol; Chen, P

2013-09-01

M13 virus (phage) has been extensively used in phage display technology and nanomaterial templating. Our research aimed to use M13 phage to template sulfur nanoparticles for making lithium ion batteries. Traditional methods for harvesting M13 phage from Escherichia coli employ polyethylene glycol (PEG)-based precipitation, and the yield is usually measured by plaque counting. With this method, PEG residue is present in the M13 phage pellet and is difficult to eliminate. To resolve this issue, a method based on isoelectric precipitation was introduced and tested. The isoelectric method resulted in the production of purer phage with a higher yield, compared to the traditional PEG-based method. There is no significant variation in infectivity of the phage prepared using isoelectric precipitation, and the dynamic light scattering data indirectly prove that the phage structure is not damaged by pH adjustment. To maximize phage production, a dry-weight yield curve of M13 phage for various culture times was produced. The yield curve is proportional to the growth curve of E. coli. On a 200-mL culture scale, 0.2 g L(-1) M13 phage (dry-weight) was produced by the isoelectric precipitation method.

The effect of Mn/Ni on thermodynamic properties of critical nucleus in Fe-Cu-Mn (Ni) ternary alloys

DOE PAGES

Li, Boyan; Zhang, Lei; Li, Chengliang; ...

2018-04-18

The aging- or radiation-induced hardening of Cu/Mn/Ni precipitates in Fe alloys is one of property degradation mechanisms in structural materials in nuclear reactors. Experiments show that aging or radiation leads the formation of Cu-rich precipitates, and the addition of Mn or Ni elements enhances the precipitation kinetics. In this study, the phase-field model coupled with the constrained string method have been applied to investigate the thermodynamic properties of critical nuclei such as the minimum energy path of Cu/Mn/Ni precipitation in Fe-Cu-Mn and Fe-Cu-Ni ternary alloys. The chemical free energies used in the model are taken from CALPHAD. The simulation resultsmore » show that the formation of Cu/Mn/Ni clusters needs to overcome an energy barrier, and the precipitate has a Core-Shell structure. The thermodynamic properties of the critical nucleus are influenced by temperature and Cu/Mn/Ni overall concentrations, which are in accordance with the simulation results as well as the experimental observations.« less

The effect of Mn/Ni on thermodynamic properties of critical nucleus in Fe-Cu-Mn (Ni) ternary alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Boyan; Zhang, Lei; Li, Chengliang

The aging- or radiation-induced hardening of Cu/Mn/Ni precipitates in Fe alloys is one of property degradation mechanisms in structural materials in nuclear reactors. Experiments show that aging or radiation leads the formation of Cu-rich precipitates, and the addition of Mn or Ni elements enhances the precipitation kinetics. In this study, the phase-field model coupled with the constrained string method have been applied to investigate the thermodynamic properties of critical nuclei such as the minimum energy path of Cu/Mn/Ni precipitation in Fe-Cu-Mn and Fe-Cu-Ni ternary alloys. The chemical free energies used in the model are taken from CALPHAD. The simulation resultsmore » show that the formation of Cu/Mn/Ni clusters needs to overcome an energy barrier, and the precipitate has a Core-Shell structure. The thermodynamic properties of the critical nucleus are influenced by temperature and Cu/Mn/Ni overall concentrations, which are in accordance with the simulation results as well as the experimental observations.« less

The optimization of microalgal culturing in liquid digestate after struvite precipitation using gray relational analysis.

PubMed

Jiang, Yiqi; Wang, Hong; Wang, Wannan; Deng, Liangwei; Wang, Wenguo

2018-05-01

Liquid digestate (LD) is highly turbid and contains ammonium (NH 4 + -N), which negatively influences microalgal growth. Therefore, a method of reducing LD turbidity and NH 4 + -N content is proposed, using struvite precipitation. To obtain struvite precipitation supernatant with an ideal UV transmittance, NH 4 + -N concentration, and N/P ratio for microalgal growth, the effects of pH and the molar ratio of NH 4 + /Mg 2+ /PO 4 3- were studied. Results show that the optimal NH 4 + /Mg 2+ /PO 4 3- molar ratio was 1:1.5:1.5, with a pH value of 8.5, following NaOH addition. Gray relational analysis (GRA) was applied to obtain a relative gray scale for the evaluation of multiple outputs. Results show that Chlorella regularis FACHB-1068 was the optimal microalgae species to support growth in the struvite precipitation supernatant. Using struvite precipitation and treatment with cultured C. regularis FACHB-1068 for 7 days, the removal efficiencies of NH 4 + -N, PO 4 3- -P, and COD in LD were 96.52, 99.33, and 35.30%, respectively.

Precipitation Data Merging over Mountainous Areas Using Satellite Estimates and Sparse Gauge Observations (PDMMA-USESGO) for Hydrological Modeling — A Case Study over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Yang, Z.; Hsu, K. L.; Sorooshian, S.; Xu, X.

2017-12-01

Precipitation in mountain regions generally occurs with high-frequency-intensity, whereas it is not well-captured by sparsely distributed rain-gauges imposing a great challenge on water management. Satellite-based Precipitation Estimation (SPE) provides global high-resolution alternative data for hydro-climatic studies, but are subject to considerable biases. In this study, a model named PDMMA-USESGO for Precipitation Data Merging over Mountainous Areas Using Satellite Estimates and Sparse Gauge Observations is developed to support precipitation mapping and hydrological modeling in mountainous catchments. The PDMMA-USESGO framework includes two calculating steps—adjusting SPE biases and merging satellite-gauge estimates—using the quantile mapping approach, a two-dimensional Gaussian weighting scheme (considering elevation effect), and an inverse root mean square error weighting method. The model is applied and evaluated over the Tibetan Plateau (TP) with the PERSIANN-CCS precipitation retrievals (daily, 0.04°×0.04°) and sparse observations from 89 gauges, for the 11-yr period of 2003-2013. To assess the data merging effects on streamflow modeling, a hydrological evaluation is conducted over a watershed in southeast TP based on the Soil and Water Assessment Tool (SWAT). Evaluation results indicate effectiveness of the model in generating high-resolution-accuracy precipitation estimates over mountainous terrain, with the merged estimates (Mer-SG) presenting consistently improved correlation coefficients, root mean square errors and absolute mean biases from original satellite estimates (Ori-CCS). It is found the Mer-SG forced streamflow simulations exhibit great improvements from those simulations using Ori-CCS, with coefficient of determination (R2) and Nash-Sutcliffe efficiency reach to 0.8 and 0.65, respectively. The presented model and case study serve as valuable references for the hydro-climatic applications using remote sensing-gauge information in other mountain areas of the world.

A new ionospheric electron precipitation module coupled with RAM-SCB within the geospace general circulation model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Yiqun; Jordanova, Vania K.; Ridley, Aaron J.

Electron precipitation down to the atmosphere due to wave-particle scattering in the magnetosphere contributes significantly to the auroral ionospheric conductivity. In order to obtain the auroral conductivity in global MHD models that are incapable of capturing kinetic physics in the magnetosphere, MHD parameters are often used to estimate electron precipitation flux for the conductivity calculation. Such an MHD approach, however, lacks self-consistency in representing the magnetosphere-ionosphere coupling processes. In this study we improve the coupling processes in global models with a more physical method. We calculate the physics-based electron precipitation from the ring current and map it to the ionosphericmore » altitude for solving the ionospheric electrodynamics. In particular, we use the BATS-R-US (Block Adaptive Tree Scheme-Roe type-Upstream) MHD model coupled with the kinetic ring current model RAM-SCB (Ring current-Atmosphere interaction Model with Self-Consistent Magnetic field (B)) that solves pitch angle-dependent electron distribution functions, to study the global circulation dynamics during the 25–26 January 2013 storm event. Since the electron precipitation loss is mostly governed by wave-particle resonant scattering in the magnetosphere, we further investigate two loss methods of specifying electron precipitation loss associated with wave-particle interactions: (1) using pitch angle diffusion coefficients D αα(E,α) determined from the quasi-linear theory, with wave spectral and plasma density obtained from statistical observations (named as “diffusion coefficient method”) and (2) using electron lifetimes τ(E) independent on pitch angles inferred from the above diffusion coefficients (named as “lifetime method”). We found that both loss methods demonstrate similar temporal evolution of the trapped ring current electrons, indicating that the impact of using different kinds of loss rates is small on the trapped electron population. Furthermore, for the precipitated electrons, the lifetime method hardly captures any precipitation in the large L shell (i.e., 4 < L < 6.5) region, while the diffusion coefficient method produces much better agreement with NOAA/POES measurements, including the spatial distribution and temporal evolution of electron precipitation in the region from the premidnight through the dawn to the dayside. Further comparisons of the precipitation energy flux to DMSP observations indicates that the new physics-based precipitation approach using diffusion coefficients for the ring current electron loss can explain the diffuse electron precipitation in the dawn sector, such as the enhanced precipitation flux at auroral latitudes and flux drop near the subauroral latitudes, but the traditional MHD approach largely overestimates the precipitation flux at lower latitudes.« less

A new ionospheric electron precipitation module coupled with RAM-SCB within the geospace general circulation model

DOE PAGES

Yu, Yiqun; Jordanova, Vania K.; Ridley, Aaron J.; ...

2016-09-01

Electron precipitation down to the atmosphere due to wave-particle scattering in the magnetosphere contributes significantly to the auroral ionospheric conductivity. In order to obtain the auroral conductivity in global MHD models that are incapable of capturing kinetic physics in the magnetosphere, MHD parameters are often used to estimate electron precipitation flux for the conductivity calculation. Such an MHD approach, however, lacks self-consistency in representing the magnetosphere-ionosphere coupling processes. In this study we improve the coupling processes in global models with a more physical method. We calculate the physics-based electron precipitation from the ring current and map it to the ionosphericmore » altitude for solving the ionospheric electrodynamics. In particular, we use the BATS-R-US (Block Adaptive Tree Scheme-Roe type-Upstream) MHD model coupled with the kinetic ring current model RAM-SCB (Ring current-Atmosphere interaction Model with Self-Consistent Magnetic field (B)) that solves pitch angle-dependent electron distribution functions, to study the global circulation dynamics during the 25–26 January 2013 storm event. Since the electron precipitation loss is mostly governed by wave-particle resonant scattering in the magnetosphere, we further investigate two loss methods of specifying electron precipitation loss associated with wave-particle interactions: (1) using pitch angle diffusion coefficients D αα(E,α) determined from the quasi-linear theory, with wave spectral and plasma density obtained from statistical observations (named as “diffusion coefficient method”) and (2) using electron lifetimes τ(E) independent on pitch angles inferred from the above diffusion coefficients (named as “lifetime method”). We found that both loss methods demonstrate similar temporal evolution of the trapped ring current electrons, indicating that the impact of using different kinds of loss rates is small on the trapped electron population. Furthermore, for the precipitated electrons, the lifetime method hardly captures any precipitation in the large L shell (i.e., 4 < L < 6.5) region, while the diffusion coefficient method produces much better agreement with NOAA/POES measurements, including the spatial distribution and temporal evolution of electron precipitation in the region from the premidnight through the dawn to the dayside. Further comparisons of the precipitation energy flux to DMSP observations indicates that the new physics-based precipitation approach using diffusion coefficients for the ring current electron loss can explain the diffuse electron precipitation in the dawn sector, such as the enhanced precipitation flux at auroral latitudes and flux drop near the subauroral latitudes, but the traditional MHD approach largely overestimates the precipitation flux at lower latitudes.« less

Enhanced precipitation variability decreases grass- and increases shrub-productivity

PubMed Central

Gherardi, Laureano A.; Sala, Osvaldo E.

2015-01-01

Although projections of precipitation change indicate increases in variability, most studies of impacts of climate change on ecosystems focused on effects of changes in amount of precipitation, overlooking precipitation variability effects, especially at the interannual scale. Here, we present results from a 6-y field experiment, where we applied sequences of wet and dry years, increasing interannual precipitation coefficient of variation while maintaining a precipitation amount constant. Increased precipitation variability significantly reduced ecosystem primary production. Dominant plant-functional types showed opposite responses: perennial-grass productivity decreased by 81%, whereas shrub productivity increased by 67%. This pattern was explained by different nonlinear responses to precipitation. Grass productivity presented a saturating response to precipitation where dry years had a larger negative effect than the positive effects of wet years. In contrast, shrubs showed an increasing response to precipitation that resulted in an increase in average productivity with increasing precipitation variability. In addition, the effects of precipitation variation increased through time. We argue that the differential responses of grasses and shrubs to precipitation variability and the amplification of this phenomenon through time result from contrasting root distributions of grasses and shrubs and competitive interactions among plant types, confirmed by structural equation analysis. Under drought conditions, grasses reduce their abundance and their ability to absorb water that then is transferred to deep soil layers that are exclusively explored by shrubs. Our work addresses an understudied dimension of climate change that might lead to widespread shrub encroachment reducing the provisioning of ecosystem services to society. PMID:26417095

Associating extreme precipitation events to parent cyclones in gridded data

NASA Astrophysics Data System (ADS)

Rhodes, Ruari; Shaffrey, Len; Gray, Sue

2015-04-01

When analysing the relationship of regional precipitation to its parent cyclone, it is insufficient to consider the cyclone's region of influence as a fixed radius from the centre due to the irregular shape of rain bands. A new method is therefore presented which allows the use of objective feature tracking data in the analysis of regional precipitation. Utilising the spatial extent of precipitation in gridded datasets, the most appropriate cyclone(s) may be associated with regional precipitation events. This method is applied in the context of an analysis of the influence of clustering and stalling of extra-tropical cyclones in the North Atlantic on total precipitation accumulations over England and Wales. Cyclone counts and residence times are presented for historical records (ERA-Interim) and future projections (HadGEM2-ES) of extreme (> 98th percentile) precipitation accumulations over England and Wales, for accumulation periods ranging from one day to one month.

Reference values assessment in a Mediterranean population for small dense low-density lipoprotein concentration isolated by an optimized precipitation method.

PubMed

Fernández-Cidón, Bárbara; Padró-Miquel, Ariadna; Alía-Ramos, Pedro; Castro-Castro, María José; Fanlo-Maresma, Marta; Dot-Bach, Dolors; Valero-Politi, José; Pintó-Sala, Xavier; Candás-Estébanez, Beatriz

2017-01-01

High serum concentrations of small dense low-density lipoprotein cholesterol (sd-LDL-c) particles are associated with risk of cardiovascular disease (CVD). Their clinical application has been hindered as a consequence of the laborious current method used for their quantification. Optimize a simple and fast precipitation method to isolate sd-LDL particles and establish a reference interval in a Mediterranean population. Forty-five serum samples were collected, and sd-LDL particles were isolated using a modified heparin-Mg 2+ precipitation method. sd-LDL-c concentration was calculated by subtracting high-density lipoprotein cholesterol (HDL-c) from the total cholesterol measured in the supernatant. This method was compared with the reference method (ultracentrifugation). Reference values were estimated according to the Clinical and Laboratory Standards Institute and The International Federation of Clinical Chemistry and Laboratory Medicine recommendations. sd-LDL-c concentration was measured in serums from 79 subjects with no lipid metabolism abnormalities. The Passing-Bablok regression equation is y = 1.52 (0.72 to 1.73) + 0.07 x (-0.1 to 0.13), demonstrating no significant statistical differences between the modified precipitation method and the ultracentrifugation reference method. Similarly, no differences were detected when considering only sd-LDL-c from dyslipidemic patients, since the modifications added to the precipitation method facilitated the proper sedimentation of triglycerides and other lipoproteins. The reference interval for sd-LDL-c concentration estimated in a Mediterranean population was 0.04-0.47 mmol/L. An optimization of the heparin-Mg 2+ precipitation method for sd-LDL particle isolation was performed, and reference intervals were established in a Spanish Mediterranean population. Measured values were equivalent to those obtained with the reference method, assuring its clinical application when tested in both normolipidemic and dyslipidemic subjects.

Affinity-based precipitation via a bivalent peptidic hapten for the purification of monoclonal antibodies.

PubMed

Handlogten, Michael W; Stefanick, Jared F; Deak, Peter E; Bilgicer, Basar

2014-09-07

In a previous study, we demonstrated a non-chromatographic affinity-based precipitation method, using trivalent haptens, for the purification of mAbs. In this study, we significantly improved this process by using a simplified bivalent peptidic hapten (BPH) design, which enables facile and rapid purification of mAbs while overcoming the limitations of the previous trivalent design. The improved affinity-based precipitation method (ABP(BPH)) combines the simplicity of salt-induced precipitation with the selectivity of affinity chromatography for the purification of mAbs. The ABP(BPH) method involves 3 steps: (i) precipitation and separation of protein contaminants larger than immunoglobulins with ammonium sulfate; (ii) selective precipitation of the target-antibody via BPH by inducing antibody-complex formation; (iii) solubilization of the antibody pellet and removal of BPH with membrane filtration resulting in the pure antibody. The ABP(BPH) method was evaluated by purifying the pharmaceutical antibody trastuzumab from common contaminants including CHO cell conditioned media, DNA, ascites fluid, other antibodies, and denatured antibody with >85% yield and >97% purity. Importantly, the purified antibody demonstrated native binding activity to cell lines expressing the target protein, HER2. Combined, the ABP(BPH) method is a rapid and scalable process for the purification of antibodies with the potential to improve product quality while decreasing purification costs.

Encapsulation of albumin in self-assembled layer-by-layer microcapsules: comparison of co-precipitation and adsorption techniques.

PubMed

Labala, Suman; Mandapalli, Praveen Kumar; Bhatnagar, Shubhmita; Venuganti, Venkata Vamsi Krishna

2015-01-01

The objective of this study is to prepare and characterize polymeric self-assembled layer-by-layer microcapsules (LbL-MC) to deliver a model protein, bovine serum albumin (BSA). The aim is to compare the BSA encapsulation in LbL-MC using co-precipitation and adsorption methods. In co-precipitation method, BSA was co-precipitated with growing calcium carbonate particles to form a core template. Later, poly(styrene sulfonate) and poly(allylamine hydrochloride) were sequentially adsorbed onto the CaCO3 templates. In adsorption method, preformed LbL-MC were incubated with BSA and encapsulation efficiency is optimized for pH and salt concentration. Free and BSA-encapsulated LbL-MC were characterized using Zetasizer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and differential scanning calorimeter. Later, in vitro release studies were performed using dialysis membrane method at pH 4, 7.4 and 9. Results from Zetasizer and SEM showed free LbL-MC with an average size and zeta-potential of 2.0 ± 0.6 μm and 8.1 ± 1.9 mV, respectively. Zeta-potential of BSA-loaded LbL-MC was (-)7.4 ± 0.7 mV and (-)5.7 ± 1.0 mV for co-precipitation and adsorption methods, respectively. In adsorption method, BSA encapsulation in LbL-MC was found to be greater at pH 6.0 and 0.2 M NaCl. Co-precipitation method provided four-fold greater encapsulation efficiency (%) of BSA in LbL-MC compared with adsorption method. At pH 4, the BSA release from LbL-MC was extended up to 120 h. Polyacrylamide gel electrophoresis showed that BSA encapsulated in LBL-MC through co-precipitation is stable toward trypsin treatment. In conclusion, co-precipitation method provided greater encapsulation of BSA in LbL-MC. Furthermore, LbL-MC can be developed as carriers for pH-controlled protein delivery.

Relevance of the correlation between precipitation and the 0 °C isothermal altitude for extreme flood estimation

NASA Astrophysics Data System (ADS)

Zeimetz, Fraenz; Schaefli, Bettina; Artigue, Guillaume; García Hernández, Javier; Schleiss, Anton J.

2017-08-01

Extreme floods are commonly estimated with the help of design storms and hydrological models. In this paper, we propose a new method to take into account the relationship between precipitation intensity (P) and air temperature (T) to account for potential snow accumulation and melt processes during the elaboration of design storms. The proposed method is based on a detailed analysis of this P-T relationship in the Swiss Alps. The region, no upper precipitation intensity limit is detectable for increasing temperature. However, a relationship between the highest measured temperature before a precipitation event and the duration of the subsequent event could be identified. An explanation for this relationship is proposed here based on the temperature gradient measured before the precipitation events. The relevance of these results is discussed for an example of Probable Maximum Precipitation-Probable Maximum Flood (PMP-PMF) estimation for the high mountainous Mattmark dam catchment in the Swiss Alps. The proposed method to associate a critical air temperature to a PMP is easily transposable to similar alpine settings where meteorological soundings as well as ground temperature and precipitation measurements are available. In the future, the analyses presented here might be further refined by distinguishing between precipitation event types (frontal versus orographic).

The Effect of Precipitate Evolution on Austenite Grain Growth in RAFM Steel.

PubMed

Yan, Biyu; Liu, Yongchang; Wang, Zejun; Liu, Chenxi; Si, Yonghong; Li, Huijun; Yu, Jianxing

2017-09-01

To study the effects of various types of precipitates and precipitate evolution behavior on austenite (size and phase fraction) in reduced activation ferritic/martensitic (RAFM) steel, RAFM steel was heated to various austenitizing temperatures. The microstructures of specimens were observed using optical microscopy (OM) and transmission electron microscopy (TEM). The results indicate that the M 23 C₆ and MX precipitates gradually coarsen and dissolve into the matrix as the austenitizing temperatures increase. The M 23 C₆ precipitates dissolve completely at 1100 °C, while the MX precipitates dissolve completely at 1200 °C. The evolution of two types of precipitate has a significant effect on the size of austenite. Based on the Zener pinning model, the effect of precipitate evolution on austenite grain size is quantified. It was found that the coarsening and dissolution of M 23 C₆ and MX precipitates leads to a decrease in pinning pressure on grain boundaries, facilitating the rapid growth of austenite grains. The austenite phase fraction is also affected by the coarsening and dissolution of precipitates.

The Effect of Precipitate Evolution on Austenite Grain Growth in RAFM Steel

PubMed Central

Yan, Biyu; Liu, Yongchang; Wang, Zejun; Liu, Chenxi; Si, Yonghong; Li, Huijun; Yu, Jianxing

2017-01-01

To study the effects of various types of precipitates and precipitate evolution behavior on austenite (size and phase fraction) in reduced activation ferritic/martensitic (RAFM) steel, RAFM steel was heated to various austenitizing temperatures. The microstructures of specimens were observed using optical microscopy (OM) and transmission electron microscopy (TEM). The results indicate that the M23C6 and MX precipitates gradually coarsen and dissolve into the matrix as the austenitizing temperatures increase. The M23C6 precipitates dissolve completely at 1100 °C, while the MX precipitates dissolve completely at 1200 °C. The evolution of two types of precipitate has a significant effect on the size of austenite. Based on the Zener pinning model, the effect of precipitate evolution on austenite grain size is quantified. It was found that the coarsening and dissolution of M23C6 and MX precipitates leads to a decrease in pinning pressure on grain boundaries, facilitating the rapid growth of austenite grains. The austenite phase fraction is also affected by the coarsening and dissolution of precipitates. PMID:28862680

Effect of sodium lauryl sulfate in dissolution media on dissolution of hard gelatin capsule shells.

PubMed

Zhao, Fang; Malayev, Vyacheslav; Rao, Venkatramana; Hussain, Munir

2004-01-01

Sodium lauryl sulfate (SLS) is a commonly used surfactant in dissolution media for poorly water soluble drugs. However, it has occasionally been observed that SLS negatively impacts the dissolution of drug products formulated in gelatin capsules. This study investigated the effect of SLS on the dissolution of hard gelatin capsule shells. The USP paddle method was used with online UV monitoring at 214 nm (peptide bond). Empty size #0 capsule shells were held to the bottom of the dissolution vessel by magnetic three-prong sinkers. SLS significantly slowed down the dissolution of gelatin shells at pH < 5. Visually, the gelatin shells transformed into some less-soluble precipitate under these conditions. This precipitate was found to contain a higher sulfur content than the gelatin control sample by elemental analysis, indicating that SLS is part of the precipitate. Additionally, the slowdown of capsule shell dissolution was shown to be dependent on the SLS concentration and the ionic strength of the media. SLS interacts with gelatin to form a less-soluble precipitate at pH < 5. The use of SLS in dissolution media at acidic pH should be carefully evaluated for gelatin capsule products.

Investigation of discharged aerosol nanoparticles during chemical precipitation and spray pyrolysis for developing safety measures in the nano research laboratory.

PubMed

Kolesnikov, Еvgeny; Karunakaran, Gopalu; Godymchuk, Anna; Vera, Levina; Yudin, Andrey Grigorjevich; Gusev, Alexander; Kuznetsov, Denis

2017-05-01

Nowadays, the demands for the nanoparticles are increasing due to their tremendous applications in various fields. As a consequence, the discharge of nanoparticles into the atmosphere and environment is also increasing, posing a health threat and environmental damage in terms of pollution. Thus, an extensive research is essential to evaluate the discharge of these nanoparticles into the environment. Keeping this in mind, the present investigation aimed to analyze the discharge of aerosol nanoparticles that are synthesized in the laboratory via chemical precipitation and spray pyrolysis methods. The results indicated that the chemical precipitation method discharges a higher concentration of nanoparticles in the work site when compared to the spray pyrolysis method. The aerosol concentration also varied with the different steps involved during the synthesis of nanoparticles. The average particle's concentration in air for chemical precipitation and spray pyrolysis methods was around 1,037,476 and 883,421particles/cm 3 . In addition, the average total discharge of nanoparticles in the entire laboratory was also examined. A significant variation in the concentration of nanoparticles was noticed, during the processing of materials and the concentration of particles (14-723nm) exceeding the daily allowed concentration to about 70-170 times was observed over a period of 6 months. Thus, the results of the present study will be very useful in developing safety measures and would help in organizing the rules for people working in nanotechnology laboratories to minimize the hazardous effects. Copyright © 2017 Elsevier Inc. All rights reserved.

Separation of ovotransferrin and ovomucoid from chicken egg white.

PubMed

Abeyrathne, E D N S; Lee, H Y; Ahn, D U

2014-04-01

Ovotransferrin and ovomucoid were separated using 2 methods after extracting the ovotransferrin- and ovomucoid-containing fraction from egg white. Diluted egg white (2×) was added to Fe(3+) and treated with 43% ethanol (final concentration). After centrifugation, the supernatant was collected and treated with either a high-level ethanol (61% final concentration) or an acidic salt combination (2.5% ammonium sulfate and 2.5% citric acid) to separate ovotransferrin and ovomucoid. For the high-level of ethanol method, ovotransferrin was precipitated using 61% ethanol. After centrifugation, the precipitant was dissolved in 9 vol. of distilled water and the residual ethanol in the solution was removed using ultrafiltration. The supernatant, mainly containing ovomucoid, was diluted with 4 vol. of water, had ethanol removed, and was then concentrated and used as the ovomucoid fraction. For the acidic salt precipitation method, the ethanol in the supernatant was removed first. The ethanol-free solution was then concentrated and treated with a 2.5% ammonium sulfate and 2.5% citric acid combination. After centrifugation, the precipitant was used as the ovotransferrin and the supernatant as the ovomucoid fraction. The ovomucoid fraction from both of the protocols was further purified by heating at 65°C for 20 min and the impurities were removed by centrifugation. The yields of ovomucoid and ovotransferrin were >96 and >92%, respectively. The purity of ovomucoid was >89% and that of the ovotransferrin was >88%. The ELISA results confirmed that the activity of the separated ovotransferrin was >95%. Both of the protocols separated ovotransferrin and ovomucoid effectively and the methods were simple, fast, and easy to scale up.

[Effects of precipitation intensity on soil organic carbon fractions and their distribution under subtropical forests of South China].

PubMed

Chen, Xiao-mei; Liu, Ju-xiu; Deng, Qi; Chu, Guo-wei; Zhou, Guo-yi; Zhang, De-qiang

2010-05-01

From December 2006 to June 2008, a field experiment was conducted to study the effects of natural precipitation, doubled precipitation, and no precipitation on the soil organic carbon fractions and their distribution under a successional series of monsoon evergreen broad-leaf forest, pine and broad-leaf mixed forest, and pine forest in Dinghushan Mountain of Southern China. Different precipitation treatments had no significant effects on the total organic carbon (TOC) concentration in the same soil layer under the same forest type (P > 0.05). In treatment no precipitation, particulate organic carbon (POC) and light fraction organic carbon (LFOC) were mainly accumulated in surface soil layer (0-10 cm); but in treatments natural precipitation and doubled precipitation, the two fractions were infiltrated to deeper soil layers. Under pine forest, soil readily oxidizable organic carbon (ROC) was significantly higher in treatment no precipitation than in treatments natural precipitation and doubled precipitation (P < 0.05). The percentage of soil POC, ROC, and LFOC to soil TOC was much greater under the forests at early successional stage than at climax stage, suggesting that the forest at early successional stage might not be an ideal place for soil organic carbon storage. Precipitation intensity less affected TOC, but had greater effects on the labile components POC, ROC, and LFOC.

Specific solubilization of impurities in culture media: Arg solution improves purification of pH-responsive tag CspB50 with Teriparatide.

PubMed

Oki, Shogo; Nonaka, Takahiro; Shiraki, Kentaro

2018-06-01

Protein purification using non-chromatographic methods is a simple technique that avoids costly resin. Recently, a cell surface protein B (CspB) tag has been developed for a pH-responsive tag for protein purification by solid-liquid separation. Proteins fused with the CspB tag show reversible insolubilization at acidic pH that can be used in solid-liquid separation for protein purification. However, brown-color impurities from co-precipitation hamper further analysis of the target proteins. In this study, we investigated the effect of additives on the co-precipitation of CspB-tagged Teriparatide (CspB50TEV-Teriparatide) expressed in Corynebacterium glutamicum and associated impurities. Arginine (Arg) at 1.0 M was found to be the most effective additive for removing impurities, particularly carotenoids and nucleic acids. Furthermore, all impurities detected in the fluorescence and absorbance spectra were successfully removed by the repetition of precipitation-redissolution in the Arg solution. The precipitation yield of the CspB50TEV-Teriparatide did not change with the addition of Arg and the repetition of the precipitation-redissolution process. Collectively, our findings indicate that the specific desorption of π-electron rich compounds by Arg may be useful in conjunction with the pH-responsive CspB tag for solid-liquid protein purification. Copyright © 2018 Elsevier Inc. All rights reserved.

Increased precipitation accelerates soil organic matter turnover associated with microbial community composition in topsoil of alpine grassland on the eastern Tibetan Plateau.

PubMed

Han, Conghai; Wang, Zongli; Si, Guicai; Lei, Tianzhu; Yuan, Yanli; Zhang, Gengxin

2017-10-01

Large quantities of carbon are stored in alpine grassland of the Tibetan Plateau, which is extremely sensitive to climate change. However, it remains unclear whether soil organic matter (SOM) in different layers responds to climate change analogously, and whether microbial communities play vital roles in SOM turnover of topsoil. In this study we measured and collected SOM turnover by the 14 C method in alpine grassland to test climatic effects on SOM turnover in soil profiles. Edaphic properties and microbial communities in the northwestern Qinghai Lake were investigated to explore microbial influence on SOM turnover. SOM turnover in surface soil (0-10 cm) was more sensitive to precipitation than that in subsurface layers (10-40 cm). Precipitation also imposed stronger effects on the composition of microbial communities in the surface layer than that in deeper soil. At the 5-10 cm depth, the SOM turnover rate was positively associated with the bacteria/fungi biomass ratio and the relative abundance of Acidobacteria, both of which are related to precipitation. Partial correlation analysis suggested that increased precipitation could accelerate the SOM turnover rate in topsoil by structuring soil microbial communities. Conversely, carbon stored in deep soil would be barely affected by climate change. Our results provide valuable insights into the dynamics and storage of SOM in alpine grasslands under future climate scenarios.

METHOD OF SEPARATING FROTHS FROM LIQUIDS

DOEpatents

Monet, G.P.

1958-01-21

A method for separating solids and precipitates from liquids is described. The method is particularly adapted for and valuable in processing highly radioactive solutions. It consists in essence, in employing the principles of froth flotation to effect the separation of approximately 99% of the solids present. An apparatus, consisting of a system of pipes, valves and vessels, for carrying out the process of this patent is also described therein.

Parameter Uncertainty on AGCM-simulated Tropical Cyclones

NASA Astrophysics Data System (ADS)

He, F.

2015-12-01

This work studies the parameter uncertainty on tropical cyclone (TC) simulations in Atmospheric General Circulation Models (AGCMs) using the Reed-Jablonowski TC test case, which is illustrated in Community Atmosphere Model (CAM). It examines the impact from 24 parameters across the physical parameterization schemes that represent the convection, turbulence, precipitation and cloud processes in AGCMs. The one-at-a-time (OAT) sensitivity analysis method first quantifies their relative importance on TC simulations and identifies the key parameters to the six different TC characteristics: intensity, precipitation, longwave cloud radiative forcing (LWCF), shortwave cloud radiative forcing (SWCF), cloud liquid water path (LWP) and ice water path (IWP). Then, 8 physical parameters are chosen and perturbed using the Latin-Hypercube Sampling (LHS) method. The comparison between OAT ensemble run and LHS ensemble run shows that the simulated TC intensity is mainly affected by the parcel fractional mass entrainment rate in Zhang-McFarlane (ZM) deep convection scheme. The nonlinear interactive effect among different physical parameters is negligible on simulated TC intensity. In contrast, this nonlinear interactive effect plays a significant role in other simulated tropical cyclone characteristics (precipitation, LWCF, SWCF, LWP and IWP) and greatly enlarge their simulated uncertainties. The statistical emulator Extended Multivariate Adaptive Regression Splines (EMARS) is applied to characterize the response functions for nonlinear effect. Last, we find that the intensity uncertainty caused by physical parameters is in a degree comparable to uncertainty caused by model structure (e.g. grid) and initial conditions (e.g. sea surface temperature, atmospheric moisture). These findings suggest the importance of using the perturbed physics ensemble (PPE) method to revisit tropical cyclone prediction under climate change scenario.

A polychromatic turbidity microplate assay to distinguish discovery stage drug molecules with beneficial precipitation properties.

PubMed

Morrison, John; Nophsker, Michelle; Elzinga, Paul; Donoso, Maria; Park, Hyunsoo; Haskell, Roy

2017-10-05

A material sparing microplate screening assay was developed to evaluate and compare the precipitation of discovery stage drug molecules as a function of time, concentration and media composition. Polychromatic turbidity time course profiles were collected for cinnarizine, probucol, dipyridamole as well as BMS-932481, and compared with turbidity profiles of monodisperse particle size standards. Precipitation for select sample conditions were further characterized at several time points by size, morphology, amount and form via laser diffraction, microscopy, size based particle counting and X-ray diffraction respectively. Wavelength dependent turbidity was found indicative of nanoprecipitate, while wavelength independent turbidity was consistent with larger microprecipitate formation. A transition from wavelength dependent to wavelength independent turbidity occurred for nanoparticle to microparticle growth, and a decrease in wavelength independent turbidity correlated with continued growth in size of microparticles. Other sudden changes in turbidity signal over time such as rapid fluctuation, a decrease in slope or a sharp inversion were correlated with very large or aggregated macro-precipitates exceeding 100μm in diameter, a change in the rate of precipitate formation or an amorphous to crystalline form conversion respectively. The assay provides an effective method to efficiently monitor and screen the precipitation fates of drug molecules, even during the early stages of discovery with limited amounts of available material. This capability highlights molecules with beneficial precipitation properties that are able to generate and maintain solubility enabling amorphous or nanoparticle precipitates. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhancing phosphorus release from waste activated sludge containing ferric or aluminum phosphates by EDTA addition during anaerobic fermentation process.

PubMed

Zou, Jinte; Zhang, Lili; Wang, Lin; Li, Yongmei

2017-03-01

The effect of ethylene diamine tetraacetic acid (EDTA) addition on phosphorus release from biosolids and phosphate precipitates during anaerobic fermentation was investigated. Meanwhile, the impact of EDTA addition on the anaerobic fermentation process was revealed. The results indicate that EDTA addition significantly enhanced the release of phosphorus from biosolids, ferric phosphate precipitate and aluminum phosphate precipitate during anaerobic fermentation, which is attributed to the complexation of metal ions and damage of cell membrane caused by EDTA. With the optimal EDTA addition of 19.5 mM (0.41 gEDTA/gSS), phosphorus release efficiency from biosolids was 82%, which was much higher than that (40%) without EDTA addition. Meanwhile, with 19.5 mM EDTA addition, almost all the phosphorus in ferric phosphate precipitate was released, while only 57% of phosphorus in aluminum phosphate precipitate was released. This indicates that phosphorus in ferric phosphate precipitate was much easier to be released than that in aluminum phosphate precipitate during anaerobic fermentation of sludge. In addition, proper EDTA addition facilitated the production of soluble total organic carbon and volatile fatty acids, as well as solid reduction during sludge fermentation, although methane production could be inhibited. Therefore, EDTA addition can be used as an alternative method for recovering phosphorus from waste activated sludge containing ferric or aluminum precipitates, as well as recovery of soluble carbon source. Copyright © 2016 Elsevier Ltd. All rights reserved.

Relative importance of precipitation frequency and intensity in inter-annual variation of precipitation in Singapore during 1980-2013

NASA Astrophysics Data System (ADS)

Li, Xin; Babovic, Vladan

2017-04-01

Observed studies on inter-annual variation of precipitation provide insight into the response of precipitation to anthropogenic climate change and natural climate variability. Inter-annual variation of precipitation results from the concurrent variations of precipitation frequency and intensity, understanding of the relative importance of frequency and intensity in the variability of precipitation can help fathom its changing properties. Investigation of the long-term changes of precipitation schemes has been extensively carried out in many regions across the world, however, detailed studies of the relative importance of precipitation frequency and intensity in inter-annual variation of precipitation are still limited, especially in the tropics. Therefore, this study presents a comprehensive framework to investigate the inter-annual variation of precipitation and the dominance of precipitation frequency and intensity in a tropical urban city-state, Singapore, based on long-term (1980-2013) daily precipitation series from 22 rain gauges. First, an iterative Mann-Kendall trend test method is applied to detect long-term trends in precipitation total, frequency and intensity at both annual and seasonal time scales. Then, the relative importance of precipitation frequency and intensity in inducing the inter-annual variation of wet-day precipitation total is analyzed using a dominance analysis method based on linear regression. The results show statistically significant upward trends in wet-day precipitation total, frequency and intensity at annual time scale, however, these trends are not evident during the monsoon seasons. The inter-annual variation of wet-day precipitation is mainly dominated by precipitation intensity for most of the stations at annual time scale and during the Northeast monsoon season. However, during the Southwest monsoon season, the inter-annual variation of wet-day precipitation is mainly dominated by precipitation frequency. These results have implications for water resources management practices in Singapore.

Cross-seasonal effects on waterfowl productivity: Implications under climate change

USGS Publications Warehouse

Osnas, Erik; Zhao, Qing; Runge, Michael C.; Boomer, G Scott

2016-01-01

Previous efforts to relate winter-ground precipitation to subsequent reproductive success as measured by the ratio of juveniles to adults in the autumn failed to account for increased vulnerability of juvenile ducks to hunting and uncertainty in the estimated age ratio. Neglecting increased juvenile vulnerability will positively bias the mean productivity estimate, and neglecting increased vulnerability and estimation uncertainty will positively bias the year-to-year variance in productivity because raw age ratios are the product of sampling variation, the year-specific vulnerability, and year-specific reproductive success. Therefore, we estimated the effects of cumulative winter precipitation in the California Central Valley and the Mississippi Alluvial Valley on pintail (Anas acuta) and mallard (Anas platyrhnchos) reproduction, respectively, using hierarchical Bayesian methods to correct for sampling bias in productivity estimates and observation error in covariates. We applied the model to a hunter-collected parts survey implemented by the United States Fish and Wildlife Service and band recoveries reported to the United States Geological Survey Bird Banding Laboratory using data from 1961 to 2013. We compared our results to previous estimates that used simple linear regression on uncorrected age ratios from a smaller subset of years in pintail (1961–1985). Like previous analyses, we found large and consistent effects of population size and wetland conditions in prairie Canada on mallard productivity, and large effects of population size and mean latitude of the observed breeding population on pintail productivity. Unlike previous analyses, we report a large amount of uncertainty in the estimated effects of wintering-ground precipitation on pintail and mallard productivity, with considerable uncertainty in the sign of the estimated main effect, although the posterior medians of precipitation effects were consistent with past studies. We found more consistent estimates in the sign of an interaction effect between population size and precipitation, suggesting that wintering-ground precipitation has a larger effect in years of high population size, especially for pintail. When we used the estimated effects in a population model to derive a sustainable harvest and population size projection (i.e., a yield curve), there was considerable uncertainty in the effect of increased or decreased wintering-ground precipitation on sustainable harvest potential and population size. These results suggest that the mechanism of cross-seasonal effects between winter habitat and reproduction in ducks occurs through a reduction in the strength of density dependence in years of above-average wintering-ground precipitation. We suggest additional investigation of the underlying mechanisms and that habitat managers and decision-makers consider the level of uncertainty in these estimates when attempting to integrate habitat management and harvest management decisions. Collection of annual data on the status of wintering-ground habitat in a rigorous sampling framework would likely be the most direct way to improve understanding of mechanisms and inform management.

PRECIPITATION METHOD OF SEPARATING PLUTONIUM FROM CONTAMINATING ELEMENTS

DOEpatents

Sutton, J.B.

1958-02-18

This patent relates to an improved method for the decontamination of plutonium. The process consists broadly in an improvement in a method for recovering plutonium from radioactive uranium fission products in aqueous solutions by decontamination steps including byproduct carrier precipitation comprising the step of introducing a preformed aqueous slurry of a hydroxide of a metal of group IV B into any aqueous acidic solution which contains the plutonium in the hexavalent state, radioactive uranium fission products contaminant and a by-product carrier precipitate and separating the metal hydroxide and by-product precipitate from the solution. The process of this invention is especially useful in the separation of plutonium from radioactive zirconium and columbium fission products.

Simulation of Water Sources and Precipitation Recycling for the MacKenzie, Mississippi and Amazon River Basins

NASA Technical Reports Server (NTRS)

Bosilovich, Michael G.; Chern, Jiun-Dar

2005-01-01

An atmospheric general circulation model simulation for 1948-1997 of the water budgets for the MacKenzie, Mississippi and Amazon River basins is presented. In addition to the water budget, we include passive tracers to identify the geographic sources of water for the basins, and the analysis focuses on the mechanisms contributing to precipitation recycling in each basin. While each basin s precipitation recycling has a strong dependency on evaporation during the mean annual cycle, the interannual variability of the recycling shows important relationships with the atmospheric circulation. The MacKenzie River basin has only a weak interannual dependency on evaporation, where the variations in zonal moisture transport from the Pacific Ocean can affect the basin water cycle. On the other hand, the Mississippi River basin has strong interannual dependencies on evaporation. While the precipitation recycling weakens with increased low level jet intensity, the evaporation variations exert stronger influence in providing water vapor for convective precipitation at the convective cloud base. High precipitation recycling is also found to be partly connected to warm SSTs in the tropical Pacific Ocean. The Amazon River basin evaporation exhibits small interannual variations, so that the interannual variations of precipitation recycling are related to atmospheric moisture transport from the tropical south Atlantic Ocean. Increasing SSTs over the 50-year period are causing increased easterly transport across the basin. As moisture transport increases, the Amazon precipitation recycling decreases (without real time varying vegetation changes). In addition, precipitation recycling from a bulk diagnostic method is compared to the passive tracer method used in the analysis. While the mean values are different, the interannual variations are comparable between each method. The methods also exhibit similar relationships to the terms of the basin scale water budgets.

Indirect downscaling of global circulation model data based on atmospheric circulation and temperature for projections of future precipitation in hourly resolution

NASA Astrophysics Data System (ADS)

Beck, F.; Bárdossy, A.

2013-07-01

Many hydraulic applications like the design of urban sewage systems require projections of future precipitation in high temporal resolution. We developed a method to predict the regional distribution of hourly precipitation sums based on daily mean sea level pressure and temperature data from a Global Circulation Model. It is an indirect downscaling method avoiding uncertain precipitation data from the model. It is based on a fuzzy-logic classification of atmospheric circulation patterns (CPs) that is further subdivided by means of the average daily temperature. The observed empirical distributions at 30 rain gauges to each CP-temperature class are assumed as constant and used for projections of the hourly precipitation sums in the future. The method was applied to the CP-temperature sequence derived from the 20th century run and the scenario A1B run of ECHAM5. According to ECHAM5, the summers in southwest Germany will become progressively drier. Nevertheless, the frequency of the highest hourly precipitation sums will increase. According to the predictions, estival water stress and the risk of extreme hourly precipitation will both increase simultaneously during the next decades.

Statistical-Dynamical Seasonal Forecasts of Central-Southwest Asian Winter Precipitation.

NASA Astrophysics Data System (ADS)

Tippett, Michael K.; Goddard, Lisa; Barnston, Anthony G.

2005-06-01

Interannual precipitation variability in central-southwest (CSW) Asia has been associated with East Asian jet stream variability and western Pacific tropical convection. However, atmospheric general circulation models (AGCMs) forced by observed sea surface temperature (SST) poorly simulate the region's interannual precipitation variability. The statistical-dynamical approach uses statistical methods to correct systematic deficiencies in the response of AGCMs to SST forcing. Statistical correction methods linking model-simulated Indo-west Pacific precipitation and observed CSW Asia precipitation result in modest, but statistically significant, cross-validated simulation skill in the northeast part of the domain for the period from 1951 to 1998. The statistical-dynamical method is also applied to recent (winter 1998/99 to 2002/03) multimodel, two-tier December-March precipitation forecasts initiated in October. This period includes 4 yr (winter of 1998/99 to 2001/02) of severe drought. Tercile probability forecasts are produced using ensemble-mean forecasts and forecast error estimates. The statistical-dynamical forecasts show enhanced probability of below-normal precipitation for the four drought years and capture the return to normal conditions in part of the region during the winter of 2002/03.May Kabul be without gold, but not without snow.—Traditional Afghan proverb

Carrageenan :the difference between PNG and KCL gel precipitation method as Lactobacillus acidophilus encapsulation material

NASA Astrophysics Data System (ADS)

Setijawati, D.; Nursyam, H.; Salis, H.

2018-04-01

The study on the effects of using of materials and methods in the preparation of the microcapsules Lactobacillus acidophilus towards the viability has been done. The research method used is experimental laboratory design. Variable research was kind of material (A) as the first factor with sub factor (A1 = Eucheuma cottonii) (A2 = Eucheuma spinosum) (A3 = mixture of Eucheuma cottonii and Eucheuma spinosum 1:1 ratio), while the second factor is a method of extraction to produce caragenan (B) with sub factor (B1 = Philipine Natural Grade modification) (B2 = KCl gel Press Precipitation). Analysis of different influences uses Analysis Of Varians followed by Fisher’s test. Analysis of data uses Mini tab 16. The results shows that the kind of extraction factors and methods gave significantly different effects on the viability of Lactobacillus acidophilus. The highest mean of Viablity obtained in the treatment of materials with a mixture of Eucheuma cottonii and Eucheuma spinosum and used KCl Gel Press method is equal to 7.14 log (CFU / mL). It is ssuggested using of kappa-iota carrageenanmixture asencapsulation material with KCl Gel Press method on Lactobacillus acidophilus microencapsulation process because it treatment gavethe highest average of Lactobacillus acidophilus viability.

A resampling procedure for generating conditioned daily weather sequences

USGS Publications Warehouse

Clark, Martyn P.; Gangopadhyay, Subhrendu; Brandon, David; Werner, Kevin; Hay, Lauren E.; Rajagopalan, Balaji; Yates, David

2004-01-01

A method is introduced to generate conditioned daily precipitation and temperature time series at multiple stations. The method resamples data from the historical record “nens” times for the period of interest (nens = number of ensemble members) and reorders the ensemble members to reconstruct the observed spatial (intersite) and temporal correlation statistics. The weather generator model is applied to 2307 stations in the contiguous United States and is shown to reproduce the observed spatial correlation between neighboring stations, the observed correlation between variables (e.g., between precipitation and temperature), and the observed temporal correlation between subsequent days in the generated weather sequence. The weather generator model is extended to produce sequences of weather that are conditioned on climate indices (in this case the Niño 3.4 index). Example illustrations of conditioned weather sequences are provided for a station in Arizona (Petrified Forest, 34.8°N, 109.9°W), where El Niño and La Niña conditions have a strong effect on winter precipitation. The conditioned weather sequences generated using the methods described in this paper are appropriate for use as input to hydrologic models to produce multiseason forecasts of streamflow.

Novel Injectable Calcium Phosphate Bone Cement from Wet Chemical Precipitation Method

NASA Astrophysics Data System (ADS)

Hablee, S.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.; Singh, R.

2017-06-01

Calcium phosphate cement has been prepared via chemical precipitation method for injectable bone filling materials. Calcium hydroxide, Ca(OH)2, and diammonium hydrogen phosphate, (NH4)2HPO4, were used as calcium and phosphorus precursors respectively. The synthesized powder was mixed with water at different powder-to-liquid (P/L) ratios, which was adjusted at 0.8, 0.9, 1.0, 1.1 and 1.2. The influence of P/L ratio on the injectability, setting time and mechanical strength of calcium phosphate cement paste has been evaluated. The synthesized powder appeared as purely hydroxyapatite with nanosized and agglomerated spherical particles. All cement pastes show excellent injectability except for the paste with P/L ratio 1.2. Calcium phosphate cement with P/L ratio 1.1 shows the ideal cement for bone filler application with good injectability, the initial and final setting times of 30 min and 160 min, and the compression strength of 2.47 MPa. The result indicated that the newly developed calcium phosphate cement is physically suitable for bone filler application. This paper presents our investigation on the effect of P/L ratio on the handling and mechanical properties of calcium phosphate cement prepared via wet chemical precipitation method.

Satellite and Model Analysis of the Atmospheric Moisture Budget in High Latitudes

NASA Technical Reports Server (NTRS)

Bromwich, David H.; Chen, Qui-Shi

2001-01-01

In order to understand variations of accumulation over Greenland, it is necessary to investigate precipitation and its variations. Observations of precipitation over Greenland are limited and generally inaccurate, but the analyzed wind, geopotential height, and moisture fields are available for recent years. The objective of this study is to enhance the dynamic method for retrieving high resolution precipitation over Greenland from the analyzed fields. The dynamic method enhanced in this study is referred to as the improved dynamic method.

The Effect of Hurricanes on Annual Precipitation in Maryland and the Connection to Global Climate Change

NASA Technical Reports Server (NTRS)

Liu, Jackie; Liu, Zhong

2015-01-01

Precipitation is a vital aspect of our lives droughts, floods and other related disasters that involve precipitation can cause costly damage in the economic system and general society. Purpose of this project is to determine what, if any effect do hurricanes have on annual precipitation in Maryland Research will be conducted on Marylands terrain, climatology, annual precipitation, and precipitation contributed from hurricanes Possible connections to climate change

Ultrasound assisted co-precipitation of nanostructured CuO-ZnO-Al2O3 over HZSM-5: effect of precursor and irradiation power on nanocatalyst properties and catalytic performance for direct syngas to DME.

PubMed

Allahyari, Somaiyeh; Haghighi, Mohammad; Ebadi, Amanollah; Hosseinzadeh, Shahin

2014-03-01

Nanostructured CuO-ZnO-Al2O3/HZSM-5 was synthesized from nitrate and acetate precursors using ultrasound assisted co-precipitation method under different irradiation powers. The CuO-ZnO-Al2O3/HZSM-5 nanocatalysts were characterized using XRD, FESEM, BET, FTIR and EDX Dot-mapping analyses. The results indicated precursor type and irradiation power have significant influences on phase structure, morphology, surface area and functional groups. It was observed that the acetate formulated CuO-ZnO-Al2O3/HZSM-5 nanocatalyst have smaller CuO crystals with better dispersion and stronger interaction between components in comparison to nitrate based nanocatalysts. Ultrasound assisted co-precipitation synthesis method resulted in nanocatalyst with more uniform morphology compared to conventional method and increasing irradiation power yields smaller particles with better dispersion and higher surface area. Additionally the crystallinity of CuO is lower at high irradiation powers leading to stronger interaction between metal oxides. The nanocatalysts performance were tested at 200-300 °C, 10-40 bar and space velocity of 18,000-36,000 cm(3)/g h with the inlet gas composition of H2/CO = 2/1 in a stainless steel autoclave reactor. The acetate based nanocatalysts irradiated with higher levels of power exhibited better reactivity in terms of CO conversion and DME yield. While there is an optimal temperature for CO conversion and DME yield in direct synthesis of DME, CO conversion and DME yield both increase with the pressure increase. Furthermore ultrasound assisted co-precipitation method yields more stable CuO-ZnO-Al2O3/HZSM-5 nanocatalyst while conventional precipitated nanocatalyst lost their activity ca. 18% and 58% in terms of CO conversion and DME yield respectively in 24 h time on stream test.

THE EFFECT OF SALICYLATES ON THE PRECIPITATION OF ANTIGEN WITH ANTIBODY.

PubMed

Coburn, A F; Kapp, E M

1943-02-01

1. Sodium salicylate modifies the precipitation of normal rabbit serum protein by sodium tungstate, and partially inhibits the precipitation of horse serum euglobulin by rabbit antiserum. Sodium salicylate added to a system containing crystalline egg albumin and its antibody partly prevents the formation of precipitate, the degree of inhibition being related to the concentration of salicylate. 2. Precipitation in the equivalence zone is more readily prevented by salicylate than precipitation in the region of antibody excess, the immune system becoming progressively less sensitive to the action of salicylate as the excess of antibody becomes larger. 3. Formed precipitates were partly dissolved following resuspension in the presence of salicylate. 4. The salicylate effect on immune precipitation is reversible, and appears to be due to inactivation of antibody. 5. Salicylate was more effective in preventing specific precipitation than other anions of a lyotropic series tested.

THE EFFECT OF SALICYLATES ON THE PRECIPITATION OF ANTIGEN WITH ANTIBODY

PubMed Central

Coburn, Alvin F.; Kapp, Eleanor M.

1943-01-01

1. Sodium salicylate modifies the precipitation of normal rabbit serum protein by sodium tungstate, and partially inhibits the precipitation of horse serum euglobulin by rabbit antiserum. Sodium salicylate added to a system containing crystalline egg albumin and its antibody partly prevents the formation of precipitate, the degree of inhibition being related to the concentration of salicylate. 2. Precipitation in the equivalence zone is more readily prevented by salicylate than precipitation in the region of antibody excess, the immune system becoming progressively less sensitive to the action of salicylate as the excess of antibody becomes larger. 3. Formed precipitates were partly dissolved following resuspension in the presence of salicylate. 4. The salicylate effect on immune precipitation is reversible, and appears to be due to inactivation of antibody. 5. Salicylate was more effective in preventing specific precipitation than other anions of a lyotropic series tested. PMID:19871273

Experimental Marvin Windshield Effects on Precipitation Records in Leadville, Colorado

USGS Publications Warehouse

Jarrett, Robert D.; Crow, Loren W.

1988-01-01

An evaluation of the Leadville, Colorado, precipitation records that include a reported record-breaking storm (and flood) at higher elevations in the Rocky Mountains has indicated that the use of an experimental Marvin windshield (designed to decrease the effects of wind on precipitation-gage catchment of snow during winter) resulted in substantially overregistered summer precipitation for 1919 to 1938. The July monthly precipitation for these years was over-registered by an average of 157 percent of the long-term July monthly precipitation at Leadville. The cause of the overregistration of precipitation was the almost 4-foot-top-diameter cone-shaped windshield that had the effect of 'funneling' hail and rain splash into the rain gage. Other nearby precipitation gages, which did not use this Marvin windshield, did not have this trend of increased precipitation for the same period. Streamflow records from the Leadville area also do not indicate an increase in streamflow from 1919 to 1938.

Water and nitrogen availability co-control ecosystem CO2 exchange in a semiarid temperate steppe.

PubMed

Zhang, Xiaolin; Tan, Yulian; Li, Ang; Ren, Tingting; Chen, Shiping; Wang, Lixin; Huang, Jianhui

2015-10-23

Both water and nitrogen (N) availability have significant effects on ecosystem CO2 exchange (ECE), which includes net ecosystem productivity (NEP), ecosystem respiration (ER) and gross ecosystem photosynthesis (GEP). How water and N availability influence ECE in arid and semiarid grasslands is still uncertain. A manipulative experiment with additions of rainfall, snow and N was conducted to test their effects on ECE in a semiarid temperate steppe of northern China for three consecutive years with contrasting natural precipitation. ECE increased with annual precipitation but approached peak values at different precipitation amount. Water addition, especially summer water addition, had significantly positive effects on ECE in years when the natural precipitation was normal or below normal, but showed trivial effect on GEP when the natural precipitation was above normal as effects on ER and NEP offset one another. Nitrogen addition exerted non-significant or negative effects on ECE when precipitation was low but switched to a positive effect when precipitation was high, indicating N effect triggered by water availability. Our results indicate that both water and N availability control ECE and the effects of future precipitation changes and increasing N deposition will depend on how they can change collaboratively in this semiarid steppe ecosystem.

Comparison of sprinkler droplet size and velocity measurements using a laser precipitation meter and photographic method

USDA-ARS?s Scientific Manuscript database

Kinetic energy of water droplets has a substantial effect on development of a soil surface seal and infiltration rate of bare soil. Methods for measuring sprinkler droplet size and velocity needed to calculate droplet kinetic energy have been developed and tested over the past 50 years, each with ad...

Separation of strontium from fecal matter

DOEpatents

Kester, D.K.

1995-01-03

A method is presented of separating strontium from a sample of biomass potentially contaminated with various radionuclides. After the sample is reduced, dissociated, and carried on a first precipitate of actinides, the first precipitate is removed to leave a supernate. Next, oxalic acid is added to the supernate to cause a second precipitate of strontium and calcium. Then, after separating the second precipitate, nitric acid is added to the second precipitate to cause a third precipitate of strontium. The calcium remains in solution and is discarded to leave essentially the precipitate of strontium.

Separation of strontium from fecal matter

DOEpatents

Kester, Dianne K.

1995-01-01

A method of separating strontium from a sample of biomass potentially contaminated with various radionuclides. After the sample is reduced, dissociated, and carried on a first precipitate of actinides, the first precipitate is removed to leave a supernate. Next, oxalic acid is added to the supernate to cause a second precipitate of strontium and calcium. Then, after separating the second precipitate, nitric acid is added to the second precipitate to cause a third precipitate of strontium. The calcium remains in solution and is discarded to leave essentially the precipitate of strontium.

Phosphates behaviours in conversion of FP chlorides

NASA Astrophysics Data System (ADS)

Amamoto, I.; Kofuji, H.; Myochin, M.; Takasaki, Y.; Terai, T.

2009-06-01

The spent electrolyte of the pyroprocessing by metal electrorefining method should be considered for recycling after removal of fission products (FP) such as, alkali metals (AL), alkaline earth metals (ALE), and/or rare earth elements (REE), to reduce the volume of high-level radioactive waste. Among the various methods suggested for this purpose is precipitation by converting FP from chlorides to phosphates. Authors have been carrying out the theoretical analysis and experiment showing the behaviours of phosphate precipitates so as to estimate the feasibility of this method. From acquired results, it was found that AL except lithium and ALE are unlikely to form phosphate precipitates. However their conversion behaviours including REE were compatible with the theoretical analysis; in the case of LaPO 4 as one of the REE precipitates, submicron-size particles could be observed while that of Li 3PO 4 was larger; the precipitates were apt to grow larger at higher temperature; etc.

Effective precipitation duration for runoff peaks based on catchment modelling

NASA Astrophysics Data System (ADS)

Sikorska, A. E.; Viviroli, D.; Seibert, J.

2018-01-01

Despite precipitation intensities may greatly vary during one flood event, detailed information about these intensities may not be required to accurately simulate floods with a hydrological model which rather reacts to cumulative precipitation sums. This raises two questions: to which extent is it important to preserve sub-daily precipitation intensities and how long does it effectively rain from the hydrological point of view? Both questions might seem straightforward to answer with a direct analysis of past precipitation events but require some arbitrary choices regarding the length of a precipitation event. To avoid these arbitrary decisions, here we present an alternative approach to characterize the effective length of precipitation event which is based on runoff simulations with respect to large floods. More precisely, we quantify the fraction of a day over which the daily precipitation has to be distributed to faithfully reproduce the large annual and seasonal floods which were generated by the hourly precipitation rate time series. New precipitation time series were generated by first aggregating the hourly observed data into daily totals and then evenly distributing them over sub-daily periods (n hours). These simulated time series were used as input to a hydrological bucket-type model and the resulting runoff flood peaks were compared to those obtained when using the original precipitation time series. We define then the effective daily precipitation duration as the number of hours n, for which the largest peaks are simulated best. For nine mesoscale Swiss catchments this effective daily precipitation duration was about half a day, which indicates that detailed information on precipitation intensities is not necessarily required to accurately estimate peaks of the largest annual and seasonal floods. These findings support the use of simple disaggregation approaches to make usage of past daily precipitation observations or daily precipitation simulations (e.g. from climate models) for hydrological modeling at an hourly time step.

Ultrasonically controlled particle size distribution of explosives: a safe method.

PubMed

Patil, Mohan Narayan; Gore, G M; Pandit, Aniruddha B

2008-03-01

Size reduction of the high energy materials (HEM's) by conventional methods (mechanical means) is not safe as they are very sensitive to friction and impact. Modified crystallization techniques can be used for the same purpose. The solute is dissolved in the solvent and crystallized via cooling or is precipitated out using an antisolvent. The various crystallization parameters such as temperature, antisolvent addition rate and agitation are adjusted to get the required final crystal size and morphology. The solvent-antisolvent ratio, time of crystallization and yield of the product are the key factors for controlling antisolvent based precipitation process. The advantages of cavitationally induced nucleation can be coupled with the conventional crystallization process. This study includes the effect of the ultrasonically generated acoustic cavitation phenomenon on the solvent antisolvent based precipitation process. CL20, a high-energy explosive compound, is a polyazapolycyclic caged polynitramine. CL-20 has greater energy output than existing (in-use) energetic ingredients while having an acceptable level of insensitivity to shock and other external stimuli. The size control and size distribution manipulation of the high energy material (CL20) has been successfully carried out safely and quickly along with an increase in the final mass yield, compared to the conventional antisolvent based precipitation process.

Consolidation of degraded ornamental porous limestone stone by calcium carbonate precipitation induced by the microbiota inhabiting the stone.

PubMed

Jimenez-Lopez, C; Rodriguez-Navarro, C; Piñar, G; Carrillo-Rosúa, F J; Rodriguez-Gallego, M; Gonzalez-Muñoz, M T

2007-08-01

Although it has already been shown that calcareous stone can be consolidated by using a bacterially inoculated culture medium, a more user-friendly method is the in situ application of a sterile culture medium that is able to activate, among the microbial community of the stone, those bacteria with a potential for calcium carbonate precipitation. In order to test this new method for stone consolidation, non-sterilized decayed porous limestone was immersed in sterile nutritional media. Results were compared to those of the runs in which stone sterilized prior to the treatment was used. The effects of the microbial community on stone consolidation were determined by recording the evolution of the culture media chemistry. The treated stone was tested for mechanical resistance and porosity. Results demonstrate that the tested media were able to activate bacteria from the microbial community of the stone. As a consequence of the growth of these bacteria, an alkalinization occurred that resulted in calcium carbonate precipitation. The new precipitate was compatible with the substrate and consolidated the stone without pore plugging. Therefore, a good candidate to in situ consolidate decayed porous limestone is the application of a sterile culture medium with the characteristics specified in the present study.

Enhancing droplet deposition through in-situ precipitation

PubMed Central

Damak, Maher; Mahmoudi, Seyed Reza; Hyder, Md Nasim; Varanasi, Kripa K.

2016-01-01

Retention of agricultural sprays on plant surfaces is an important challenge. Bouncing of sprayed pesticide droplets from leaves is a major source of soil and groundwater pollution and pesticide overuse. Here we report a method to increase droplet deposition through in-situ formation of hydrophilic surface defects that can arrest droplets during impact. Defects are created by simultaneously spraying oppositely charged polyelectrolytes that induce surface precipitation when two droplets come into contact. Using high-speed imaging, we study the coupled dynamics of drop impact and surface precipitate formation. We develop a physical model to estimate the energy dissipation by the defects and predict the transition from bouncing to sticking. We demonstrate macroscopic enhancements in spray retention and surface coverage for natural and synthetic non-wetting surfaces and provide insights into designing effective agricultural sprays. PMID:27572948

Decarbonization process for carbothermically produced aluminum

DOEpatents

Bruno, Marshall J.; Carkin, Gerald E.; DeYoung, David H.; Dunlap, Sr., Ronald M.

2015-06-30

A method of recovering aluminum is provided. An alloy melt having Al.sub.4C.sub.3 and aluminum is provided. This mixture is cooled and then a sufficient amount of a finely dispersed gas is added to the alloy melt at a temperature of about 700.degree. C. to about 900.degree. C. The aluminum recovered is a decarbonized carbothermically produced aluminum where the step of adding a sufficient amount of the finely dispersed gas effects separation of the aluminum from the Al.sub.4C.sub.3 precipitates by flotation, resulting in two phases with the Al.sub.4C.sub.3 precipitates being the upper layer and the decarbonized aluminum being the lower layer. The aluminum is then recovered from the Al.sub.4C.sub.3 precipitates through decanting.

Enhancing droplet deposition through in-situ precipitation

NASA Astrophysics Data System (ADS)

Damak, Maher; Mahmoudi, Seyed Reza; Hyder, Md Nasim; Varanasi, Kripa K.

2016-08-01

Retention of agricultural sprays on plant surfaces is an important challenge. Bouncing of sprayed pesticide droplets from leaves is a major source of soil and groundwater pollution and pesticide overuse. Here we report a method to increase droplet deposition through in-situ formation of hydrophilic surface defects that can arrest droplets during impact. Defects are created by simultaneously spraying oppositely charged polyelectrolytes that induce surface precipitation when two droplets come into contact. Using high-speed imaging, we study the coupled dynamics of drop impact and surface precipitate formation. We develop a physical model to estimate the energy dissipation by the defects and predict the transition from bouncing to sticking. We demonstrate macroscopic enhancements in spray retention and surface coverage for natural and synthetic non-wetting surfaces and provide insights into designing effective agricultural sprays.

Linking Air Quality and Watershed Models for Environmental Assessments: Analysis of the Effects of Model-Specific Precipitation Estimates on Calculated Water Flux

EPA Science Inventory

Directly linking air quality and watershed models could provide an effective method for estimating spatially-explicit inputs of atmospheric contaminants to watershed biogeochemical models. However, to adequately link air and watershed models for wet deposition estimates, each mod...

Multisite stochastic simulation of daily precipitation from copula modeling with a gamma marginal distribution

NASA Astrophysics Data System (ADS)

Lee, Taesam

2018-05-01

Multisite stochastic simulations of daily precipitation have been widely employed in hydrologic analyses for climate change assessment and agricultural model inputs. Recently, a copula model with a gamma marginal distribution has become one of the common approaches for simulating precipitation at multiple sites. Here, we tested the correlation structure of the copula modeling. The results indicate that there is a significant underestimation of the correlation in the simulated data compared to the observed data. Therefore, we proposed an indirect method for estimating the cross-correlations when simulating precipitation at multiple stations. We used the full relationship between the correlation of the observed data and the normally transformed data. Although this indirect method offers certain improvements in preserving the cross-correlations between sites in the original domain, the method was not reliable in application. Therefore, we further improved a simulation-based method (SBM) that was developed to model the multisite precipitation occurrence. The SBM preserved well the cross-correlations of the original domain. The SBM method provides around 0.2 better cross-correlation than the direct method and around 0.1 degree better than the indirect method. The three models were applied to the stations in the Nakdong River basin, and the SBM was the best alternative for reproducing the historical cross-correlation. The direct method significantly underestimates the correlations among the observed data, and the indirect method appeared to be unreliable.

High-range resolution spectral analysis of precipitation through range imaging of the Chung-Li VHF radar

NASA Astrophysics Data System (ADS)

Tsai, Shih-Chiao; Chen, Jenn-Shyong; Chu, Yen-Hsyang; Su, Ching-Lun; Chen, Jui-Hsiang

2018-01-01

Multi-frequency range imaging (RIM) has been operated in the Chung-Li very high-frequency (VHF) radar, located on the campus of National Central University, Taiwan, since 2008. RIM processes the echo signals with a group of closely spaced transmitting frequencies through appropriate inversion methods to obtain high-resolution distribution of echo power in the range direction. This is beneficial to the investigation of the small-scale structure embedded in dynamic atmosphere. Five transmitting frequencies were employed in the radar experiment for observation of the precipitating atmosphere during the period between 21 and 23 August 2013. Using the Capon and Fourier methods, the radar echoes were synthesized to retrieve the temporal signals at a smaller range step than the original range resolution defined by the pulse width, and such retrieved temporal signals were then processed in the Doppler frequency domain to identify the atmosphere and precipitation echoes. An analysis called conditional averaging was further executed for echo power, Doppler velocity, and spectral width to verify the potential capabilities of the retrieval processing in resolving small-scale precipitation and atmosphere structures. Point-by-point correction of range delay combined with compensation of range-weighting function effect has been performed during the retrieval of temporal signals to improve the continuity of power spectra at gate boundaries, making the small-scale structures in the power spectra more natural and reasonable. We examined stratiform and convective precipitation and demonstrated their different structured characteristics by means of the Capon-processed results. The new element in this study is the implementation of RIM on spectral analysis, especially for precipitation echoes.

Improving Lightning and Precipitation Prediction of Severe Convection Using Lightning Data Assimilation With NCAR WRF-RTFDDA

NASA Astrophysics Data System (ADS)

Wang, Haoliang; Liu, Yubao; Cheng, William Y. Y.; Zhao, Tianliang; Xu, Mei; Liu, Yuewei; Shen, Si; Calhoun, Kristin M.; Fierro, Alexandre O.

2017-11-01

In this study, a lightning data assimilation (LDA) scheme was developed and implemented in the National Center for Atmospheric Research Weather Research and Forecasting-Real-Time Four-Dimensional Data Assimilation system. In this LDA method, graupel mixing ratio (qg) is retrieved from observed total lightning. To retrieve qg on model grid boxes, column-integrated graupel mass is first calculated using an observation-based linear formula between graupel mass and total lightning rate. Then the graupel mass is distributed vertically according to the empirical qg vertical profiles constructed from model simulations. Finally, a horizontal spread method is utilized to consider the existence of graupel in the adjacent regions of the lightning initiation locations. Based on the retrieved qg fields, latent heat is adjusted to account for the latent heat releases associated with the formation of the retrieved graupel and to promote convection at the observed lightning locations, which is conceptually similar to the method developed by Fierro et al. Three severe convection cases were studied to evaluate the LDA scheme for short-term (0-6 h) lightning and precipitation forecasts. The simulation results demonstrated that the LDA was effective in improving the short-term lightning and precipitation forecasts by improving the model simulation of the qg fields, updrafts, cold pool, and front locations. The improvements were most notable in the first 2 h, indicating a highly desired benefit of the LDA in lightning and convective precipitation nowcasting (0-2 h) applications.

Purification of anti-bromelain antibodies by affinity precipitation using pNIPAm-linked bromelain.

PubMed

Mahmood, Rubab

2016-01-01

Affinity precipitation has emerged as a very useful technique for the purification of proteins. Here it has been employed for the purification of anti-bromelain antibodies from rabbit serum. A system has been developed for reversibly binding and thermoprecipitating antibodies. Anti-bromelain antibodies were raised in rabbit by immunizing it with bromelain. Poly-N-isopropylacrylamide (pNIPAm)-bromelain conjugate was prepared and incubated with rabbit serum. After that the temperature was raised for thermal precipitation of the polymer. Antibodies were then eluted from the complex by incubating it with a small volume of buffer, pH 3.0. This method is very effective in concentrating the antibodies. Purity and specificity of the antibodies were checked by gel electrophoresis and enzyme-linked immunosorbent assay (ELISA), respectively. The study of the effect of pH and temperature on the binding of the antibodies to the conjugate showed that the optimum binding occurred at pH 8.0 and 25°C.The polymer enzyme conjugate was further used for another cycle.

Analysis of the evolution of precipitation in the Haihe river basin of China under changing environment

NASA Astrophysics Data System (ADS)

Ding, Xiangyi; Liu, Jiahong; Gong, Jiaguo

2018-02-01

Precipitation is one of the important factors of water cycle and main sources of regional water resources. It is of great significance to analyze the evolution of precipitation under changing environment for identifying the evolution law of water resources, thus can provide a scientific reference for the sustainable utilization of water resources and the formulation of related policies and measures. Generally, analysis of the evolution of precipitation consists of three levels: analysis the observed precipitation change based on measured data, explore the possible factors responsible for the precipitation change, and estimate the change trend of precipitation under changing environment. As the political and cultural centre of China, the climatic conditions in the Haihe river basin have greatly changed in recent decades. This study analyses the evolution of precipitation in the basin under changing environment based on observed meteorological data, GCMs and statistical methods. Firstly, based on the observed precipitation data during 1961-2000 at 26 meteorological stations in the basin, the actual precipitation change in the basin is analyzed. Secondly, the observed precipitation change in the basin is attributed using the fingerprint-based attribution method, and the causes of the observed precipitation change is identified. Finally, the change trend of precipitation in the basin under climate change in the future is predicted based on GCMs and a statistical downscaling model. The results indicate that: 1) during 1961-2000, the precipitation in the basin showed a decreasing trend, and the possible mutation time was 1965; 2) natural variability may be the factor responsible for the observed precipitation change in the basin; 3) under climate change in the future, precipitation in the basin will slightly increase by 4.8% comparing with the average, and the extremes will not vary significantly.

An empirical method for estimating instream pre-mining pH and dissolved Cu concentration in catchments with acidic drainage and ferricrete

USGS Publications Warehouse

Nimick, D.A.; Gurrieri, J.T.; Furniss, G.

2009-01-01

Methods for assessing natural background water quality of streams affected by historical mining are vigorously debated. An empirical method is proposed in which stream-specific estimation equations are generated from relationships between either pH or dissolved Cu concentration in stream water and the Fe/Cu concentration ratio in Fe-precipitates presently forming in the stream. The equations and Fe/Cu ratios for pre-mining deposits of alluvial ferricrete then were used to reconstruct estimated pre-mining longitudinal profiles for pH and dissolved Cu in three acidic streams in Montana, USA. Primary assumptions underlying the proposed method are that alluvial ferricretes and modern Fe-precipitates share a common origin, that the Cu content of Fe-precipitates remains constant during and after conversion to ferricrete, and that geochemical factors other than pH and dissolved Cu concentration play a lesser role in determining Fe/Cu ratios in Fe-precipitates. The method was evaluated by applying it in a fourth, naturally acidic stream unaffected by mining, where estimated pre-mining pH and Cu concentrations were similar to present-day values, and by demonstrating that inflows, particularly from unmined areas, had consistent effects on both the pre-mining and measured profiles of pH and Cu concentration. Using this method, it was estimated that mining has affected about 480 m of Daisy Creek, 1.8 km of Fisher Creek, and at least 1 km of Swift Gulch. Mean values of pH decreased by about 0.6 pH units to about 3.2 in Daisy Creek and by 1-1.5 pH units to about 3.5 in Fisher Creek. In Swift Gulch, mining appears to have decreased pH from about 5.5 to as low as 3.6. Dissolved Cu concentrations increased due to mining almost 40% in Daisy Creek to a mean of 11.7 mg/L and as much as 230% in Fisher Creek to 0.690 mg/L. Uncertainty in the fate of Cu during the conversion of Fe-precipitates to ferricrete translates to potential errors in pre-mining estimates of as much as 0.25 units for pH and 22% for dissolved Cu concentration. The method warrants further testing in other mined and unmined watersheds. Comparison of pre-mining water-quality estimates derived from the ferricrete and other methods in single watersheds would be particularly valuable. The method has potential for use in monitoring remedial efforts at mine sites with ferricrete deposits. A reasonable remediation objective might be realized when the downstream pattern of Fe/Cu ratios in modern streambed Fe-precipitates corresponds to the pattern in pre-mining alluvial ferricrete deposits along a stream valley.

Concentration and Separation of Active Proteins from Potato Industry Waste Based on Low-Temperature Evaporation and Ethanol Precipitation

PubMed Central

Ahokas, Mikko; Järvinen, Juho; Toivanen, Juho; Tanskanen, Juha P.

2017-01-01

Purpose. Potato fruit juice, a residue of starch industry, contains up to 2.5% [w/w] of proteins that are potentially valuable raw-materials of food, cosmetic, and pharma industries. The recovery of protein from the potato fruit juice is limited by the lack of industrially feasible concentration and separation technologies. The present research thus aimed at development of such process for the separation of active protease inhibitors from potato fruit juice. Methods. Low temperature mechanical vapor recompression evaporation was applied for concentration of potato fruit juice followed by ethanol precipitation for recovery of active proteins. The effects of precipitation temperature and precipitative agents were investigated employing response surface modeling methodology. Results. Concentration of potato fruit juice by evaporation was successful without loss of trypsin inhibition activity. Precipitation using 6.5 M ethanol at low temperature (0–+4°C) was found suitable for the recovery of active protease inhibitors from the concentrate. Piloting at starch industry yielded 50% of total proteins, with a high quantity of active protease inhibitors and a minor inclusion of other proteins. Conclusion. Concentration by low-temperature evaporation, followed by ethanol precipitation of protease inhibitors at optimized temperature, is an attractive option for valorization of potato fruit juice. PMID:28299232

Preparation of immunoglobulin Y from egg yolk using ammonium sulfate precipitation and ion exchange chromatography.

PubMed

Ko, K Y; Ahn, D U

2007-02-01

The objective of this study was to develop an economical, simple, and large-scale separation method for IgY from egg yolk. Egg yolk diluted with 9 volumes of cold water was centrifuged after adjusting the pH to 5.0. The supernatant was added with 0.01% charcoal or 0.01% carrageenan and centrifuged at 2,800 x g for 30 min. The supernatant was filtered through a Whatman no. 1 filter paper and then the filtrate was concentrated to 20% original volume using ultrafiltration. The concentrated solution was further purified using either cation exchange chromatography or ammonium sulfate precipitation. For the cation exchange chromatography method, the concentrated sample was loaded onto a column equilibrated with 20 mM citrate-phosphate buffer at pH 4.8 and eluted with 200 mM citrate-phosphate buffer at pH 6.4. For the ammonium sulfate precipitation method, the concentrated sample was twice precipitated with 40% ammonium sulfate solution at pH 9.0. The yield and purity of IgY were determined by ELISA and electrophoresis. The yield of IgY from the cation exchange chromatography method was 30 to 40%, whereas that of the ammonium sulfate precipitation was 70 to 80%. The purity of IgY from the ammonium sulfate method was higher than that of the cation exchange chromatography. The cation exchange chromatography could handle only a small amount of samples, whereas the ammonium sulfate precipitation could handle a large volume of samples. This suggests that ammonium sulfate precipitation was a more efficient and useful purification method than cation exchange chromatography for the large-scale preparation of IgY from egg yolk.

The full annual carbon balance of a subtropical coniferous plantation is highly sensitive to autumn precipitation.

PubMed

Xu, Mingjie; Wang, Huimin; Wen, Xuefa; Zhang, Tao; Di, Yuebao; Wang, Yidong; Wang, Jianlei; Cheng, Chuanpeng; Zhang, Wenjiang

2017-08-30

Deep understanding of the effects of precipitation on carbon budgets is essential to assess the carbon balance accurately and can help predict potential variation within the global change context. Therefore, we addressed this issue by analyzing twelve years (2003-2014) of observations of carbon fluxes and their corresponding temperature and precipitation data in a subtropical coniferous plantation at the Qianyanzhou (QYZ) site, southern China. During the observation years, this coniferous ecosystem experienced four cold springs whose effects on the carbon budgets were relatively clear based on previous studies. To unravel the effects of temperature and precipitation, the effects of autumn precipitation were examined by grouping the data into two pools based on whether the years experienced cold springs. The results indicated that precipitation in autumn can accelerate the gross primary productivity (GPP) of the following year. Meanwhile, divergent effects of precipitation on ecosystem respiration (Re) were found. Autumn precipitation was found to enhance Re in normal years but the same regulation was not found in the cold-spring years. These results suggested that for long-term predictions of carbon balance in global climate change projections, the effects of precipitation must be considered to better constrain the uncertainties associated with the estimation.

Water balance at a low-level radioactive-waste disposal site

USGS Publications Warehouse

Healy, R.W.; Gray, J.R.; De Vries, G. M.; Mills, P.C.

1989-01-01

The water balance at a low-level radioactive-waste disposal site in northwestern Illinois was studied from July 1982 through June 1984. Continuous data collection allowed estimates to be made for each component of the water-balance equation independent of other components. The average annual precipitation was 948 millimeters. Average annual evapotranspiration was estimated at 637 millimeters, runoff was 160 millimeters, change in water storage in a waste-trench cover was 24 millimeters, and deep percolation was 208 millimeters. The magnitude of the difference between precipitation and all other components (81 millimeters per year) indicates that, in a similar environment, the water-budget method would be useful in estimating evapotranspiration, but questionable for estimation of other components. Precipitation depth and temporal distribution had a very strong effect on all other components of the water-balance equation. Due to the variability of precipitation from year to year, it appears that two years of data are inadequate for characterization of the long-term average water balance at the site.

[Application of continuous mixing technology in ethanol precipitation process of Salvia miltiorrhiza by using micromixer].

PubMed

Gong, Xing-Chu; Shen, Ji-Chen; Qu, Hai-Bin

2016-12-01

Continuous pharmaceutical manufacturing is one of the development directions in international pharmaceutical technology. In this study, a continuous mixing technology of ethanol and concentrated extract in the ethanol precipitation of Salvia miltiorrhiza was realized by using a membrane dispersion method. The effects of ethanol flowrate, concentrated extract flowrate, and flowrate ratio on ethanol precipitation results were investigated. With the increase of the flowrates of ethanol and concentrated extract, retention rate of active phenolic acids components was increased, and the total solid removal rate was decreased. The purity of active components in supernatants was mainly affected by the ratio of ethanol flowrate and concentrated extract flowrate. The mixing efficiency of adding ethanol under continuous flow mixing mode in this study was comparable to that of industrial ethanol precipitation. Continuous adding ethanol by using a membrane dispersion mixer is a promising technology with many advantages such as easy enlargement, large production per unit volume, and easy control. Copyright© by the Chinese Pharmaceutical Association.

Concentration of infectious hematopoietic necrosis virus from water samples by tangential flow filtration and polyethylene glycol precipitation

USGS Publications Warehouse

Batts, W.N.; Winton, J.R.

1989-01-01

Infectious hematopoietic necrosis virus (IHNV) was concentrated from water samples by polyethylene glycol (PEG) precipitation, tangential flow filtration (TFF), and by a combination of TFF followed by PEG precipitation of the retentate. Used alone, PEG increased virus titers more than 200-fold, and the efficiency of recovery was as great as 100%. Used alone, TFF concentrated IHNV more than 20-fold, and average recovery was 70%. When the two techniques were combined, 10-L water samples were reduced to about 300 mL by TFF and the virus was precipitated with PEG into a 1 to 2 g pellet; total recovery was as great as 100%. The combined techniques were used to isolate IHNV from water samples taken from a river containing adult sockeye salmon (Oncorhynchus nerka) and from a hatchery pond containing adult spring chinook salmon (O. tshawytscha). The combination of these methods was effective in concentrating and detecting IHNV from water containing only three infectious particles per 10-L sample.

[Feedforward control strategy and its application in quality improvement of ethanol precipitation process of danhong injection].

PubMed

Yan, Bin-Jun; Guo, Zheng-Tai; Qu, Hai-Bin; Zhao, Bu-Chang; Zhao, Tao

2013-06-01

In this work, a feedforward control strategy basing on the concept of quality by design was established for the manufacturing process of traditional Chinese medicine to reduce the impact of the quality variation of raw materials on drug. In the research, the ethanol precipitation process of Danhong injection was taken as an application case of the method established. Box-Behnken design of experiments was conducted. Mathematical models relating the attributes of the concentrate, the process parameters and the quality of the supernatants produced were established. Then an optimization model for calculating the best process parameters basing on the attributes of the concentrate was built. The quality of the supernatants produced by ethanol precipitation with optimized and non-optimized process parameters were compared. The results showed that using the feedforward control strategy for process parameters optimization can control the quality of the supernatants effectively. The feedforward control strategy proposed can enhance the batch-to-batch consistency of the supernatants produced by ethanol precipitation.

Artifacts introduced by ion milling in Al-Li-Cu alloys.

PubMed

Singh, A K; Imam, M A; Sadananda, K

1988-04-01

Ion milling is commonly used to prepare specimens for observation under transmission electron microscope (TEM). This technique sometimes introduces artifacts in specimens contributing to misleading interpretation of TEM results as observed in the present investigation of Al-Li-Cu alloys. This type of alloy, in general, contains several kinds of precipitates, namely delta', T1, and theta'. It is found that ion milling even for a short time produces drastic changes in the precipitate characteristics as compared to standard electropolishing methods of specimen preparation for TEM. Careful analysis of selected area diffraction patterns and micrographs shows that after ion milling delta' precipitates are very irregular, whereas other precipitates coarsen and they are surrounded by misfit dislocations. In situ hot-stage TEM experiments were performed to relate the microstructure to that observed in the ion-milled specimen. Results and causes of ion milling effects on the microstructure are discussed in relation to standard electropolishing techniques and in situ hot-stage experiment.

Effect of Silicon in U-10Mo Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kautz, Elizabeth J.; Devaraj, Arun; Kovarik, Libor

2017-08-31

This document details a method for evaluating the effect of silicon impurity content on U-10Mo alloys. Silicon concentration in U-10Mo alloys has been shown to impact the following: volume fraction of precipitate phases, effective density of the final alloy, and 235-U enrichment in the gamma-UMo matrix. This report presents a model for calculating these quantities as a function of Silicon concentration, which along with fuel foil characterization data, will serve as a reference for quality control of the U-10Mo final alloy Si content. Additionally, detailed characterization using scanning electron microscope imaging, transmission electron microscope diffraction, and atom probe tomography showedmore » that Silicon impurities present in U-10Mo alloys form a Si-rich precipitate phase.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, S.; Yang, M.; Song, X.L.

The Laves phase precipitation process was characterised by means of field emission scanning electron microscopy to demonstrate its effect on creep rupture strength of steels with a fully ferritic matrix. To eliminate the effects of carbide and carbonitride precipitations so that the creep rupture data can be analysed exclusively in relation to the Laves phase precipitation process, an alloy Fe–9Cr–3Co–3W (wt.%) without C and N additions was used for the study. Creep rupture strengths were measured and volume fraction and particle size of Laves phase precipitates in the ruptured specimens were analysed. It was found that the creep rupture strengthmore » started to collapse (or decrease more rapidly) long before the Laves phase precipitation reached equilibrium fraction. This was related to the onset of the coarsening of Laves phase particles, which precipitated only on grain boundaries and hence contributed little to precipitation strengthening. Creep deformation had no effect either on the precipitation kinetics or on the growth kinetics of Laves phase particles. - Highlights: • Laves phase precipitation at 650 °C was characterised for Fe–9Cr–3W–3Co alloy. • Laves phase precipitated predominantly on grain boundaries. • Creep deformation had no effect on Laves phase precipitation and growth kinetics. • Creep strength started to collapse long before Laves phase precipitation is ended. • Collapse of creep strength was attributed to the coarsening of Laves phase particles.« less

An Investigation of the Effects of Black Carbon on Precipitation in the Western United States

NASA Astrophysics Data System (ADS)

Tseng, Hsien-Liang Rose

Black carbon (BC), the byproduct of incomplete combustion, is considered to be the second most important anthropogenic climate forcing agent after carbon dioxide. BC warms the atmosphere by absorbing solar radiation (direct effect), alters cloud and precipitation formation by acting as cloud condensation nuclei (indirect effect), and modifies cloud distribution via cloud burn-off (semi-direct effect). Currently, there are large discrepancies in general circulation model estimates of the influence of BC on precipitation. Even less known is how BC changes precipitation on regional scales. In the drought-stricken western United States (WUS), where BC emissions are known to affect the hydrological cycle, an investigation on how BC influences precipitation is warranted. In this study, we employ the Weather Research and Forecasting-Chemistry (WRF Chem) model (version 3.6.0) with the newly chemistry- and microphysics-coupled Fu-Liou-Gu radiation scheme to study how black carbon affects precipitation by separating BC-related effects into direct and semi-direct, and indirect effects. In this three-part study, we use a recent wet year (2005) to investigate black carbon effects. We first examine BC effects during a heavy wintertime heavy precipitation event (7-11 January 2005), a heavy summertime precipitation week for comparison to the wintertime event (20-24 July 2005), and finally, examine these same effects for the months of January to June 2005 to investigate month-long trends. We find that BC suppresses precipitation, predominantly through its direct and semi-direct effects. The direct and semi-direct effects warm the air aloft, and cool the lower levels of the atmosphere (surface dimming) through the reduction of downward shortwave radiation flux at the surface. These changes in vertical temperature increase the stability of the atmosphere and reduce convective precipitation. Convective precipitation reduction accounts for approximately 60 75% of the total precipitation reduction. Additionally, cooling in the lower levels reduces evaporation from the surface, which reduces the moisture needed for non-convective precipitation. Subsequently, reduced moisture in the atmosphere suppresses non-convective precipitation by approximately 10-40%. The indirect effects also reduce precipitation, but to a much smaller extent of 5-20%. Although we use an atypical BC emission dataset is used in this study, the resulting reduction of the different types of precipitation sheds light on the physical mechanisms of BC-cloud-radiation interactions by which the reductions follow. In particular, our results highlight the importance of the cumulus and surface layer parameterizations that house the triggering mechanism and surface moisture flux parameterizations in future studies. In this research we find the NEI 2005 emissions did not significantly change precipitation. This is likely due to the aggressive emission regulations that exist for the United States. Emission regulations, however, do not exist or are enforced equally across the globe. In the developing countries that rely on inefficient cook stoves and heating systems, the populations suffer the most due to black carbon emission. Along with respiratory and cardiovascular impacts from black carbon, they may suffer from reduced water resources from suppressed precipitation, as well. In a larger sense, findings from this research serve as a platform for understanding the wider-reaching effects of black carbon on regional precipitation and drought. In particular, in areas where there are no black carbon emission regulations, this would highlight health and potentially significant environmental benefits that could be achieved from a black carbon cap and trade.

Physical retrieval of precipitation water contents from Special Sensor Microwave/Imager (SSM/I) data. Part 2: Retrieval method and applications (report version)

NASA Technical Reports Server (NTRS)

Olson, William S.

1990-01-01

A physical retrieval method for estimating precipitating water distributions and other geophysical parameters based upon measurements from the DMSP-F8 SSM/I is developed. Three unique features of the retrieval method are (1) sensor antenna patterns are explicitly included to accommodate varying channel resolution; (2) precipitation-brightness temperature relationships are quantified using the cloud ensemble/radiative parameterization; and (3) spatial constraints are imposed for certain background parameters, such as humidity, which vary more slowly in the horizontal than the cloud and precipitation water contents. The general framework of the method will facilitate the incorporation of measurements from the SSMJT, SSM/T-2 and geostationary infrared measurements, as well as information from conventional sources (e.g., radiosondes) or numerical forecast model fields.

21st Century Changes in Precipitation Extremes Based on Resolved Atmospheric Patterns

NASA Astrophysics Data System (ADS)

Gao, X.; Schlosser, C. A.; O'Gorman, P. A.; Monier, E.

2014-12-01

Global warming is expected to alter the frequency and/or magnitude of extreme precipitation events. Such changes could have substantial ecological, economic, and sociological consequences. However, climate models in general do not correctly reproduce the frequency distribution of precipitation, especially at the regional scale. In this study, a validated analogue method is employed to diagnose the potential future shifts in the probability of extreme precipitation over the United States under global warming. The method is based on the use of the resolved large-scale meteorological conditions (i.e. flow features, moisture supply) to detect the occurrence of extreme precipitation. The CMIP5 multi-model projections have been compiled for two radiative forcing scenarios (Representative Concentration Pathways 4.5 and 8.5). We further analyze the accompanying circulation features and their changes that may be responsible for shifts in extreme precipitation in response to changed climate. The application of such analogue method to detect other types of hazard events, i.e. landslides is also explored. The results from this study may guide hazardous weather watches and help society develop adaptive strategies for preventing catastrophic losses.

CO-PRECIPITATION IN QUANTITATIVE ANALYSIS. COMMUNICATION V. THE INFLUENCE EXERCISED BY COMPLEXION UPON THE PRECIPITATION OF ZIRCONIUM PHOSPHATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babko, A.K.; Shtokalo, M.I.

The influence exercised by ethylenediamino-tetraacetic acid upon some processes of precipitation was investigated. A sharp mopdification of the form of precipitate as well as a decrease of coprecipitation was ium and titanium by means of the phosphate ;method are given. (TCO-W.D.M.)

Application of hierarchical clustering method to classify of space-time rainfall patterns

NASA Astrophysics Data System (ADS)

Yu, Hwa-Lung; Chang, Tu-Je

2010-05-01

Understanding the local precipitation patterns is essential to the water resources management and flooding mitigation. The precipitation patterns can vary in space and time depending upon the factors from different spatial scales such as local topological changes and macroscopic atmospheric circulation. The spatiotemporal variation of precipitation in Taiwan is significant due to its complex terrain and its location at west pacific and subtropical area, where is the boundary between the pacific ocean and Asia continent with the complex interactions among the climatic processes. This study characterizes local-scale precipitation patterns by classifying the historical space-time precipitation records. We applied the hierarchical ascending clustering method to analyze the precipitation records from 1960 to 2008 at the six rainfall stations located in Lan-yang catchment at the northeast of the island. Our results identify the four primary space-time precipitation types which may result from distinct driving forces from the changes of atmospheric variables and topology at different space-time scales. This study also presents an important application of the statistical downscaling to combine large-scale upper-air circulation with local space-time precipitation patterns.

Assessment of Drought Severity Using Normal Precipitation Index (Case Study: Sistan and Baluchistan Province)

NASA Astrophysics Data System (ADS)

Rahimi, D.; Movahedi, S.

2009-04-01

In the last decades, water crisis is one of the most important critical phenomenons in the environment planning and human society's management which affecting on development aspects in the international, national and regional levels. In this research, have been considered the Drought as the main parameter in water rare serious. For drought assessment, can treat the different methods, such as statistical model, meteorological and hydrological methods. In this research, have been used the Normal Precipitation index to meteorological analysis of drought severity in Sistan and Baluchistan province with high drought severity during recent years. According to the obtained result, the annual precipitation of studied area was between 36 to 52 percent more than mean precipitation of province. 10%-23 percent of precipitation amount involved the drought threshold border, 3%-13 percent of precipitations contain the weakness drought, 6.7% -23 percent were considered for moderate drought, 6%-20 percent involved the severe drought and ultimately, 6.7% to 23 percent of precipitations were considered as very severe drought. Keywords: Drought, Normal index, precipitation, Sistan and Baluchistan

Fast quantification of endogenous carbohydrates in plasma using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry.

PubMed

Zhu, Bangjie; Liu, Feng; Li, Xituo; Wang, Yan; Gu, Xue; Dai, Jieyu; Wang, Guiming; Cheng, Yu; Yan, Chao

2015-01-01

Endogenous carbohydrates in biosamples are frequently highlighted as the most differential metabolites in many metabolomics studies. A simple, fast, simultaneous quantitative method for 16 endogenous carbohydrates in plasma has been developed using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry. In order to quantify 16 endogenous carbohydrates in plasma, various conditions, including columns, chromatographic conditions, mass spectrometry conditions, and plasma preparation methods, were investigated. Different conditions in this quantified analysis were performed and optimized. The reproducibility, precision, recovery, matrix effect, and stability of the method were verified. The results indicated that a methanol/acetonitrile (50:50, v/v) mixture could effectively and reproducibly precipitate rat plasma proteins. Cold organic solvents coupled with vortex for 1 min and incubated at -20°C for 20 min were the most optimal conditions for protein precipitation and extraction. The results, according to the linearity, recovery, precision, matrix effect, and stability, showed that the method was satisfactory in the quantification of endogenous carbohydrates in rat plasma. The quantified analysis of endogenous carbohydrates in rat plasma performed excellently in terms of sensitivity, high throughput, and simple sample preparation, which met the requirement of quantification in specific expanded metabolomic studies after the global metabolic profiling research. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of the Ion Exchange-Gravimetric Method for Sodium in Serum as a Definitive Method

PubMed Central

Moody, John R.; Vetter, Thomas W.

1996-01-01

An ion exchange-gravimetric method, previously developed as a National Committee for Clinical Laboratory Standards (NCCLS) reference method for the determination of sodium in human serum, has been re-evaluated and improved. Sources of analytical error in this method have been examined more critically and the overall uncertainties decreased. Additionally, greater accuracy and repeatability have been achieved by the application of this definitive method to a sodium chloride reference material. In this method sodium in serum is ion-exchanged, selectively eluted and converted to a weighable precipitate as Na2SO4. Traces of sodium eluting before or after the main fraction, and precipitate contaminants are determined instrumentally. Co-precipitating contaminants contribute less than 0.1 % while the analyte lost to other eluted ion-exchange fractions contributes less than 0.02 % to the total precipitate mass. With improvements, the relative expanded uncertainty (k = 2) of the method, as applied to serum, is 0.3 % to 0.4 % and is less than 0.1 % when applied to a sodium chloride reference material. PMID:27805122

Effects of precipitation changes on switchgrass photosynthesis, growth, and biomass: A mesocosm experiment

USDA-ARS?s Scientific Manuscript database

Climate changes, including chronic changes in precipitation amounts, will influence plant physiology and growth. However, such precipitation effects on switchgrass, a major bioenergy crop, have not been well investigated. We conducted a two-year precipitation simulation experiment using large pots...

Parameterizing microphysical effects on variances and covariances of moisture and heat content using a multivariate probability density function: a study with CLUBB (tag MVCS)

DOE PAGES

Griffin, Brian M.; Larson, Vincent E.

2016-11-25

Microphysical processes, such as the formation, growth, and evaporation of precipitation, interact with variability and covariances (e.g., fluxes) in moisture and heat content. For instance, evaporation of rain may produce cold pools, which in turn may trigger fresh convection and precipitation. These effects are usually omitted or else crudely parameterized at subgrid scales in weather and climate models.A more formal approach is pursued here, based on predictive, horizontally averaged equations for the variances, covariances, and fluxes of moisture and heat content. These higher-order moment equations contain microphysical source terms. The microphysics terms can be integrated analytically, given a suitably simplemore » warm-rain microphysics scheme and an approximate assumption about the multivariate distribution of cloud-related and precipitation-related variables. Performing the integrations provides exact expressions within an idealized context.A large-eddy simulation (LES) of a shallow precipitating cumulus case is performed here, and it indicates that the microphysical effects on (co)variances and fluxes can be large. In some budgets and altitude ranges, they are dominant terms. The analytic expressions for the integrals are implemented in a single-column, higher-order closure model. Interactive single-column simulations agree qualitatively with the LES. The analytic integrations form a parameterization of microphysical effects in their own right, and they also serve as benchmark solutions that can be compared to non-analytic integration methods.« less

Method for determining processability of a hydrocarbon containing feedstock

DOEpatents

Schabron, John F.; Rovani, Jr., Joseph F.

2013-09-10

Disclosed herein is a method involving the steps of (a) precipitating an amount of asphaltenes from a liquid sample of a first hydrocarbon-containing feedstock having solvated asphaltenes therein with one or more first solvents in a column; (b) determining one or more solubility characteristics of the precipitated asphaltenes; (c) analyzing the one or more solubility characteristics of the precipitated asphaltenes; and (d) correlating a measurement of feedstock reactivity for the first hydrocarbon-containing feedstock sample with a mathematical parameter derived from the results of analyzing the one or more solubility characteristics of the precipitated asphaltenes.

Effects of large-scale deforestation on precipitation in the monsoon regions: remote versus local effects.

PubMed

Devaraju, N; Bala, Govindasamy; Modak, Angshuman

2015-03-17

In this paper, using idealized climate model simulations, we investigate the biogeophysical effects of large-scale deforestation on monsoon regions. We find that the remote forcing from large-scale deforestation in the northern middle and high latitudes shifts the Intertropical Convergence Zone southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America, and Australia). The magnitude of the monsoonal precipitation changes depends on the location of deforestation, with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most, with 18% decline in precipitation over India. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation alongside the large local impacts on temperatures.

Development of a methodology for probable maximum precipitation estimation over the American River watershed using the WRF model

NASA Astrophysics Data System (ADS)

Tan, Elcin

A new physically-based methodology for probable maximum precipitation (PMP) estimation is developed over the American River Watershed (ARW) using the Weather Research and Forecast (WRF-ARW) model. A persistent moisture flux convergence pattern, called Pineapple Express, is analyzed for 42 historical extreme precipitation events, and it is found that Pineapple Express causes extreme precipitation over the basin of interest. An average correlation between moisture flux convergence and maximum precipitation is estimated as 0.71 for 42 events. The performance of the WRF model is verified for precipitation by means of calibration and independent validation of the model. The calibration procedure is performed only for the first ranked flood event 1997 case, whereas the WRF model is validated for 42 historical cases. Three nested model domains are set up with horizontal resolutions of 27 km, 9 km, and 3 km over the basin of interest. As a result of Chi-square goodness-of-fit tests, the hypothesis that "the WRF model can be used in the determination of PMP over the ARW for both areal average and point estimates" is accepted at the 5% level of significance. The sensitivities of model physics options on precipitation are determined using 28 microphysics, atmospheric boundary layer, and cumulus parameterization schemes combinations. It is concluded that the best triplet option is Thompson microphysics, Grell 3D ensemble cumulus, and YSU boundary layer (TGY), based on 42 historical cases, and this TGY triplet is used for all analyses of this research. Four techniques are proposed to evaluate physically possible maximum precipitation using the WRF: 1. Perturbations of atmospheric conditions; 2. Shift in atmospheric conditions; 3. Replacement of atmospheric conditions among historical events; and 4. Thermodynamically possible worst-case scenario creation. Moreover, climate change effect on precipitation is discussed by emphasizing temperature increase in order to determine the physically possible upper limits of precipitation due to climate change. The simulation results indicate that the meridional shift in atmospheric conditions is the optimum method to determine maximum precipitation in consideration of cost and efficiency. Finally, exceedance probability analyses of the model results of 42 historical extreme precipitation events demonstrate that the 72-hr basin averaged probable maximum precipitation is 21.72 inches for the exceedance probability of 0.5 percent. On the other hand, the current operational PMP estimation for the American River Watershed is 28.57 inches as published in the hydrometeorological report no. 59 and a previous PMP value was 31.48 inches as published in the hydrometeorological report no. 36. According to the exceedance probability analyses of this proposed method, the exceedance probabilities of these two estimations correspond to 0.036 percent and 0.011 percent, respectively.

Method for the decontamination of metallic surfaces

DOEpatents

Purohit, Ankur; Kaminski, Michael D.; Nunez, Luis

2003-01-01

A method of decontaminating a radioactively contaminated oxide on a surface. The radioactively contaminated oxide is contacted with a diphosphonic acid solution for a time sufficient to dissolve the oxide and subsequently produce a precipitate containing most of the radioactive values. Thereafter, the diphosphonic solution is separated from the precipitate. HEDPA is the preferred diphosphonic acid and oxidizing and reducing agents are used to initiate precipitation. SFS is the preferred reducing agent.

METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM

DOEpatents

Koshland, D.E. Jr.; Willard, J.E.

1961-08-01

A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

Computation of rainfall erosivity from daily precipitation amounts.

PubMed

Beguería, Santiago; Serrano-Notivoli, Roberto; Tomas-Burguera, Miquel

2018-10-01

Rainfall erosivity is an important parameter in many erosion models, and the EI30 defined by the Universal Soil Loss Equation is one of the best known erosivity indices. One issue with this and other erosivity indices is that they require continuous breakpoint, or high frequency time interval, precipitation data. These data are rare, in comparison to more common medium-frequency data, such as daily precipitation data commonly recorded by many national and regional weather services. Devising methods for computing estimates of rainfall erosivity from daily precipitation data that are comparable to those obtained by using high-frequency data is, therefore, highly desired. Here we present a method for producing such estimates, based on optimal regression tools such as the Gamma Generalised Linear Model and universal kriging. Unlike other methods, this approach produces unbiased and very close to observed EI30, especially when these are aggregated at the annual level. We illustrate the method with a case study comprising more than 1500 high-frequency precipitation records across Spain. Although the original records have a short span (the mean length is around 10 years), computation of spatially-distributed upscaling parameters offers the possibility to compute high-resolution climatologies of the EI30 index based on currently available, long-span, daily precipitation databases. Copyright © 2018 Elsevier B.V. All rights reserved.

Examining the Stationarity Assumption for Statistically Downscaled Climate Projections of Precipitation

NASA Astrophysics Data System (ADS)

Wootten, A.; Dixon, K. W.; Lanzante, J. R.; Mcpherson, R. A.

2017-12-01

Empirical statistical downscaling (ESD) approaches attempt to refine global climate model (GCM) information via statistical relationships between observations and GCM simulations. The aim of such downscaling efforts is to create added-value climate projections by adding finer spatial detail and reducing biases. The results of statistical downscaling exercises are often used in impact assessments under the assumption that past performance provides an indicator of future results. Given prior research describing the danger of this assumption with regards to temperature, this study expands the perfect model experimental design from previous case studies to test the stationarity assumption with respect to precipitation. Assuming stationarity implies the performance of ESD methods are similar between the future projections and historical training. Case study results from four quantile-mapping based ESD methods demonstrate violations of the stationarity assumption for both central tendency and extremes of precipitation. These violations vary geographically and seasonally. For the four ESD methods tested the greatest challenges for downscaling of daily total precipitation projections occur in regions with limited precipitation and for extremes of precipitation along Southeast coastal regions. We conclude with a discussion of future expansion of the perfect model experimental design and the implications for improving ESD methods and providing guidance on the use of ESD techniques for impact assessments and decision-support.

THE DETERMINATION OF THE MAJOR CONSTITUENTS OTHER THAN URANIUM IN BELGIAN CONGO ORE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, A.B.; Wright, J.S.; Bradfield, E.G.

1953-12-22

Methods for determining the major constituents of Belgian Congo ore other than uranium are reviewed. A method is given for the determination of cobalt by precipitation with potassium ethyl xanthate from a nitric acid solution of the ore. After wet oxidation of the precipitate, it is titrated potentiometrically in ammoniacal citrate solution with potassium ferricyanide. A method for the determination of silicon is given in which the silica is dehydrated by fuming with perchloric acid. After filtration and ignition, it is volatized as the fluoride, and the silica is deternfined from weight loss. Nickel is determined from a solution ofmore » the ore in nitric acid by double precipitation with dimethyl glyoxime after addition of citrate ion, hydroxylamine, and ammonia. Molybdenum is determined by precipitation as lead molybdate after preliminary separation with benzoin oxime. Aluminum is determined by precipitation as the benzoate, thioglycolic acid being used to complex the iron. The aluminum is then estimated gravimetrically with oxime. A composite method is presented for the deterndnation of lead, iron, alununum, calciuna, and magnesium. (C.J.G.)« less

RADIOMETRIC STUDY ON THE SUITABILITY OF CINCHONIN AS PRECIPITATION REAGENT FOR TUNGSTEN AND MOLYBDENUM (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merz, E.

1962-01-01

The precipitation of W and Mo with cinchonin was studied using P/sup 32/ , Mp/sup 99/, and W/sup 185/. The effects of the acid, acid concentration, solution volume, and precipitation time on the quantitative precipitation of the metals were determined. W was precipitated only from HCl and HNO/sub 3/, and no quantitative precipitation of Mo was obtained. No variation was found in the completeness of the precipitation using HCl concentrations of 1 to 6N, but precipitation is prevented or strongly inhibited in very strong solutions. The quantitative precipitation of W is very strongly dependent on the solution volume, but theremore » is no sharp time dependence. A study of the effectiveness of cinchonin and tannin as combined precipitation agents showed no advantage over the use of cinchonin alone, except in the removal of interferring elements in the precipitation. (J.S.R.)« less

A new approach for assimilation of two-dimensional radar precipitation in a high resolution NWP model

NASA Astrophysics Data System (ADS)

Korsholm, Ulrik; Petersen, Claus; Hansen Sass, Bent; Woetman, Niels; Getreuer Jensen, David; Olsen, Bjarke Tobias; GIll, Rasphal; Vedel, Henrik

2014-05-01

The DMI nowcasting system has been running in a pre-operational state for the past year. The system consists of hourly simulations with the High Resolution Limited Area weather model combined with surface and three-dimensional variational assimilation at each restart and nudging of satellite cloud products and radar precipitation. Nudging of a two-dimensional radar reflectivity CAPPI product is achieved using a new method where low level horizontal divergence is nudged towards pseudo observations. Pseudo observations are calculated based on an assumed relation between divergence and precipitation rate and the strength of the nudging is proportional to the offset between observed and modelled precipitation leading to increased moisture convergence below cloud base if there is an under-production of precipitation relative to the CAPPI product. If the model over-predicts precipitation, the low level moisture source is reduced, and in-cloud moisture is nudged towards environmental values. In this talk results will be discussed based on calculation of the fractions skill score in cases with heavy precipitation over Denmark. Furthermore, results from simulations combining reflectivity nudging and extrapolation of reflectivity will be shown. Results indicate that the new method leads to fast adjustment of the dynamical state of the model to facilitate precipitation release when the model precipitation intensity is too low. Removal of precipitation is also shown to be of importance and strong improvements were found in the position of the precipitation systems. Bias is reduced for low and extreme precipitation rates.

Impact of Precipitating Ice Hydrometeors on Longwave Radiative Effect Estimated by a Global Cloud-System Resolving Model

NASA Astrophysics Data System (ADS)

Chen, Ying-Wen; Seiki, Tatsuya; Kodama, Chihiro; Satoh, Masaki; Noda, Akira T.

2018-02-01

Satellite observation and general circulation model (GCM) studies suggest that precipitating ice makes nonnegligible contributions to the radiation balance of the Earth. However, in most GCMs, precipitating ice is diagnosed and its radiative effects are not taken into account. Here we examine the longwave radiative impact of precipitating ice using a global nonhydrostatic atmospheric model with a double-moment cloud microphysics scheme. An off-line radiation model is employed to determine cloud radiative effects according to the amount and altitude of each type of ice hydrometeor. Results show that the snow radiative effect reaches 2 W m-2 in the tropics, which is about half the value estimated by previous studies. This effect is strongly dependent on the vertical separation of ice categories and is partially generated by differences in terminal velocities, which are not represented in GCMs with diagnostic precipitating ice. Results from sensitivity experiments that artificially change the categories and altitudes of precipitating ice show that the simulated longwave heating profile and longwave radiation field are sensitive to the treatment of precipitating ice in models. This study emphasizes the importance of incorporating appropriate treatments for the radiative effects of precipitating ice in cloud and radiation schemes in GCMs in order to capture the cloud radiative effects of upper level clouds.

Global modeling of land water and energy balances. Part III: Interannual variability

USGS Publications Warehouse

Shmakin, A.B.; Milly, P.C.D.; Dunne, K.A.

2002-01-01

The Land Dynamics (LaD) model is tested by comparison with observations of interannual variations in discharge from 44 large river basins for which relatively accurate time series of monthly precipitation (a primary model input) have recently been computed. When results are pooled across all basins, the model explains 67% of the interannual variance of annual runoff ratio anomalies (i.e., anomalies of annual discharge volume, normalized by long-term mean precipitation volume). The new estimates of basin precipitation appear to offer an improvement over those from a state-of-the-art analysis of global precipitation (the Climate Prediction Center Merged Analysis of Precipitation, CMAP), judging from comparisons of parallel model runs and of analyses of precipitation-discharge correlations. When the new precipitation estimates are used, the performance of the LaD model is comparable to, but not significantly better than, that of a simple, semiempirical water-balance relation that uses only annual totals of surface net radiation and precipitation. This implies that the LaD simulations of interannual runoff variability do not benefit substantially from information on geographical variability of land parameters or seasonal structure of interannual variability of precipitation. The aforementioned analyses necessitated the development of a method for downscaling of long-term monthly precipitation data to the relatively short timescales necessary for running the model. The method merges the long-term data with a reference dataset of 1-yr duration, having high temporal resolution. The success of the method, for the model and data considered here, was demonstrated in a series of model-model comparisons and in the comparisons of modeled and observed interannual variations of basin discharge.

Hydrology of the North Cascades region, Washington: 2. A proposed hydrometeorological streamflow prediction method

USGS Publications Warehouse

Tangborn, Wendell V.; Rasmussen, Lowell A.

1976-01-01

On the basis of a linear relationship between winter (October-April) precipitation and annual runoff from a drainage basin (Rasmussen and Tangborn, 1976) a physically reasonable model for predicting summer (May-September) streamflow from drainages in the North Cascades region was developed. This hydrometeorological prediction method relates streamflow for a season beginning on the day of prediction to the storage (including snow, ice, soil moisture, and groundwater) on that day. The spring storage is inferred from an input-output relationship based on the principle of conservation of mass: spring storage equals winter precipitation on the basin less winter runoff from the basin and less winter evapotranspiration, which is presumed to be small. The method of prediction is based on data only from the years previous to the one for which the prediction is made, and the system is revised each year as data for the previous year become available. To improve the basin storage estimate made in late winter or early spring, a short-season runoff prediction is made. The errors resulting from this short-term prediction are used to revise the storage estimate and improve the later prediction. This considerably improves the accuracy of the later prediction, especially for periods early in the summer runoff season. The optimum length for the test period appears to be generally less than a month for east side basins and between 1 and 2 months for those on the west side of the Cascade Range. The time distribution of the total summer runoff can be predicted when this test season is used so that on May 1 monthly streamflow for the May-September season can be predicted. It was found that summer precipitation and the time of minimum storage are two error sources that were amenable to analysis. For streamflow predictions in seasons beginning in early spring the deviation of the subsequent summer precipitation from a long-period average will contribute up to 53% of the prediction error. This contribution decreases to nearly zero during the summer and then rises slightly for late summer predictions. The reason for the smaller than expected effect of summer precipitation is thought to be due to the compensating effect of increased evaporative losses and increased infiltration when precipitation is greater than normal during the summer months. The error caused by the beginning winter month (assumed to be October in this study) not coinciding with the time of minimum storage was examined; it appears that October may be the best average beginning winter month for most drainages but that a more detailed study is needed. The optimum beginning of the winter season appears to vary from August to October when individual years are examined. These results demonstrate that standard precipitation and runoff measurements in the North Cascades region are adequate for constructing a predictive hydrologic model. This model can be used to make streamflow predictions that compare favorably with current multiple regression methods based on mountain snow surveys. This method has the added advantages of predicting the space and time distributions of storage and summer runoff.

Effects of grazing on leaf area index, fractional cover and evapotranspiration by a desert phreatophyte community at a former uranium mill site on the Colorado Plateau

USGS Publications Warehouse

Bresloff, Cynthia J.; Nguyen, Uyen; Glenn, Edward P.; Waugh, Jody; Nagler, Pamela L.

2013-01-01

This study employed ground and remote sensing methods to monitor the effects of grazing on leaf area index (LAI), fractional cover (fc) and evapotranspiration (ET) of a desert phreatophyte community over an 11 year period at a former uranium mill site on the Colorado Plateau, U.S. Nitrate, ammonium and sulfate are migrating away from the mill site in a shallow alluvial aquifer. The phreatophyte community, consisting of Atriplex canescens (ATCA) and Sarcobatus vermiculatus (SAVE) shrubs, intercepts groundwater and could potentially slow the movement of the contaminant plume through evapotranspiration (ET). However, the site has been heavily grazed by livestock, reducing plant cover and LAI. We used livestock exclosures and revegetation plots to determine the effects of grazing on LAI, fc and ET, then projected the findings over the whole site using multi-platform remote sensing methods. We show that ET is approximately equal to annual precipitation at the site, but when ATCA and SAVE are protected from grazing they can develop high fc and LAI values, and ET can exceed annual precipitation, with the excess coming from groundwater discharge. Therefore, control of grazing could be an effective method to slow migration of contaminants at this and similar sites in the western U.S.

Downscaling Satellite Precipitation with Emphasis on Extremes: A Variational ℓ1-Norm Regularization in the Derivative Domain

NASA Astrophysics Data System (ADS)

Foufoula-Georgiou, E.; Ebtehaj, A. M.; Zhang, S. Q.; Hou, A. Y.

2014-05-01

The increasing availability of precipitation observations from space, e.g., from the Tropical Rainfall Measuring Mission (TRMM) and the forthcoming Global Precipitation Measuring (GPM) Mission, has fueled renewed interest in developing frameworks for downscaling and multi-sensor data fusion that can handle large data sets in computationally efficient ways while optimally reproducing desired properties of the underlying rainfall fields. Of special interest is the reproduction of extreme precipitation intensities and gradients, as these are directly relevant to hazard prediction. In this paper, we present a new formalism for downscaling satellite precipitation observations, which explicitly allows for the preservation of some key geometrical and statistical properties of spatial precipitation. These include sharp intensity gradients (due to high-intensity regions embedded within lower-intensity areas), coherent spatial structures (due to regions of slowly varying rainfall), and thicker-than-Gaussian tails of precipitation gradients and intensities. Specifically, we pose the downscaling problem as a discrete inverse problem and solve it via a regularized variational approach (variational downscaling) where the regularization term is selected to impose the desired smoothness in the solution while allowing for some steep gradients (called ℓ1-norm or total variation regularization). We demonstrate the duality between this geometrically inspired solution and its Bayesian statistical interpretation, which is equivalent to assuming a Laplace prior distribution for the precipitation intensities in the derivative (wavelet) space. When the observation operator is not known, we discuss the effect of its misspecification and explore a previously proposed dictionary-based sparse inverse downscaling methodology to indirectly learn the observation operator from a data base of coincidental high- and low-resolution observations. The proposed method and ideas are illustrated in case studies featuring the downscaling of a hurricane precipitation field.

Variations of net ecosystem production due to seasonal precipitation differences in a tropical dry forest of northwest Mexico

NASA Astrophysics Data System (ADS)

Verduzco, Vivian S.; Garatuza-Payán, Jaime; Yépez, Enrico A.; Watts, Christopher J.; Rodríguez, Julio C.; Robles-Morua, Agustin; Vivoni, Enrique R.

2015-10-01

Due to their large extent and high primary productivity, tropical dry forests (TDF) are important contributors to atmospheric carbon exchanges in subtropical and tropical regions. In northwest Mexico, a bimodal precipitation regime that includes winter precipitation derived from Pacific storms and summer precipitation from the North American monsoon (NAM) couples water availability with ecosystem processes. We investigated the net ecosystem production of a TDF ecosystem using a 4.5 year record of water and carbon fluxes obtained from the eddy covariance method complemented with remotely sensed data. We identified a large CO2 efflux at the start of the summer season that is strongly related to the preceding winter precipitation and greenness. Since this CO2 efflux occurs prior to vegetation green-up, we infer that respiration is mainly due to decomposition of soil organic matter accumulated from the prior growing season. Overall, ecosystem respiration has an important effect on the net ecosystem production but can be overwhelmed by the strength of the primary productivity during the NAM. Precipitation characteristics during NAM have significant controls on sustaining carbon fixation in the TDF into the fall season. We identified that a threshold of ~350 to 400 mm of monsoon precipitation leads to a switch in the annual carbon balance in the TDF ecosystem from a net source (+102 g C/m2/yr) to a net sink (-249 g C/m2/yr). This monsoonal precipitation threshold is typically exceeded one out of every 2 years. The close coupling of winter and summer periods with respect to carbon fluxes suggests that the annual carbon balance is dependent on precipitation amounts in both seasons in TDF ecosystems.

Downscaling Satellite Precipitation with Emphasis on Extremes: A Variational 1-Norm Regularization in the Derivative Domain

NASA Technical Reports Server (NTRS)

Foufoula-Georgiou, E.; Ebtehaj, A. M.; Zhang, S. Q.; Hou, A. Y.

2013-01-01

The increasing availability of precipitation observations from space, e.g., from the Tropical Rainfall Measuring Mission (TRMM) and the forthcoming Global Precipitation Measuring (GPM) Mission, has fueled renewed interest in developing frameworks for downscaling and multi-sensor data fusion that can handle large data sets in computationally efficient ways while optimally reproducing desired properties of the underlying rainfall fields. Of special interest is the reproduction of extreme precipitation intensities and gradients, as these are directly relevant to hazard prediction. In this paper, we present a new formalism for downscaling satellite precipitation observations, which explicitly allows for the preservation of some key geometrical and statistical properties of spatial precipitation. These include sharp intensity gradients (due to high-intensity regions embedded within lower-intensity areas), coherent spatial structures (due to regions of slowly varying rainfall),and thicker-than-Gaussian tails of precipitation gradients and intensities. Specifically, we pose the downscaling problem as a discrete inverse problem and solve it via a regularized variational approach (variational downscaling) where the regularization term is selected to impose the desired smoothness in the solution while allowing for some steep gradients(called 1-norm or total variation regularization). We demonstrate the duality between this geometrically inspired solution and its Bayesian statistical interpretation, which is equivalent to assuming a Laplace prior distribution for the precipitation intensities in the derivative (wavelet) space. When the observation operator is not known, we discuss the effect of its misspecification and explore a previously proposed dictionary-based sparse inverse downscaling methodology to indirectly learn the observation operator from a database of coincidental high- and low-resolution observations. The proposed method and ideas are illustrated in case studies featuring the downscaling of a hurricane precipitation field.

Identifying and Analyzing Uncertainty Structures in the TRMM Microwave Imager Precipitation Product over Tropical Ocean Basins

NASA Technical Reports Server (NTRS)

Liu, Jianbo; Kummerow, Christian D.; Elsaesser, Gregory S.

2016-01-01

Despite continuous improvements in microwave sensors and retrieval algorithms, our understanding of precipitation uncertainty is quite limited, due primarily to inconsistent findings in studies that compare satellite estimates to in situ observations over different parts of the world. This study seeks to characterize the temporal and spatial properties of uncertainty in the Tropical Rainfall Measuring Mission Microwave Imager surface rainfall product over tropical ocean basins. Two uncertainty analysis frameworks are introduced to qualitatively evaluate the properties of uncertainty under a hierarchy of spatiotemporal data resolutions. The first framework (i.e. 'climate method') demonstrates that, apart from random errors and regionally dependent biases, a large component of the overall precipitation uncertainty is manifested in cyclical patterns that are closely related to large-scale atmospheric modes of variability. By estimating the magnitudes of major uncertainty sources independently, the climate method is able to explain 45-88% of the monthly uncertainty variability. The percentage is largely resolution dependent (with the lowest percentage explained associated with a 1 deg x 1 deg spatial/1 month temporal resolution, and highest associated with a 3 deg x 3 deg spatial/3 month temporal resolution). The second framework (i.e. 'weather method') explains regional mean precipitation uncertainty as a summation of uncertainties associated with individual precipitation systems. By further assuming that self-similar recurring precipitation systems yield qualitatively comparable precipitation uncertainties, the weather method can consistently resolve about 50 % of the daily uncertainty variability, with only limited dependence on the regions of interest.

Recovery of phosphorous from industrial waste water by oxidation and precipitation.

PubMed

Ylmén, Rikard; Gustafsson, Anna M K; Camerani-Pinzani, Caterina; Steenari, Britt-Marie

2017-07-03

This paper describes the development of a method for recovery of phosphorous from one of the waste waters at an Akzo Nobel chemical plant in Ale close to Göteborg. It was found that it is possible to transform the phosphorous in the waste water to a saleable product, i.e. a slowly dissolving fertilizer. The developed process includes oxidation of phosphite to phosphate with hydrogen peroxide and heat. The phosphate is then precipitated as crystalline struvite (ammonium magnesium phosphate) by the addition of magnesium chloride. The environmental impacts of the new method were compared with those of the current method using life cycle assessment. It was found that the methodology developed in this project was an improvement compared with the current practice regarding element resource depletion and eutrophication. However, the effect on global warming would be greater with the new method. There could however be several ways to decrease the global warming effect. Since most of the carbon dioxide emissions come from the production of magnesium chloride from carbonates, changing to utilization of a magnesium chloride from desalination of seawater or from recycling of PVC would decrease the carbon footprint significantly.

Quantitative assessment of the impacts of climate change and human activities on runoff change in a typical karst watershed, SW China.

PubMed

Wu, Luhua; Wang, Shijie; Bai, Xiaoyong; Luo, Weijun; Tian, Yichao; Zeng, Cheng; Luo, Guangjie; He, Shiyan

2017-12-01

The Yinjiang River watershed is a typical karst watershed in Southwest China. The present study explored runoff change and its responses to different driving factors in the Yinjiang River watershed over the period of 1984 to 2015. The methods of cumulative anomaly, continuous wavelet analysis, Mann-Kendall rank correlation trend test, and Hurst exponent were applied to analyze the impacts of climate change and human activities on runoff change. The contributions of climate change and human activities to runoff change were quantitatively assessed using the comparative method of the slope changing ratio of cumulative quantity (SCRCQ). The following results were obtained: (1) From 1984 to 2015, runoff and precipitation exhibited no-significant increasing trend, whereas evaporation exhibited significant decreasing trend. (2) In the future, runoff, precipitation, and evaporation will exhibit weak anti-persistent feature with different persistent times. This feature indicated that in their persistent times, runoff and precipitation will continuously decline, whereas evaporation will continuously increase. (3) Runoff and precipitation were well-synchronized with abrupt change features and stage characteristics, and exhibited consistent multi-timescale characteristics that were different from that of evaporation. (4) The contribution of precipitation to runoff change was 50%-60% and was considered high and stable. The contribution of evaporation to runoff change was 10%-90% and was variable with a positive or negative effects. The contribution of human activities to runoff change was 20%-60% and exerted a low positive or negative effect. (5) Climatic factors highly contributed to runoff change. By contrast, the contribution of human activities to runoff change was low. The contribution of climatic factors to runoff change was highly variable because of differences among base periods. In conclusion, this paper provides a basic theoretical understanding of the main factors that contribute to runoff change in a karst watershed. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigating the Control of Ocean-Atmospheric Oscillations on Global Terrestrial Evaporation

NASA Astrophysics Data System (ADS)

Martens, B.; Waegeman, W.; Dorigo, W.; Verhoest, N.; Miralles, D. G.

2017-12-01

Intra-annual and multi-decadal variability in Earth's climate is strongly driven by periodic oscillations in the coupled state of our atmosphere and ocean. These oscillations do not only impact climate in nearby regions, but can also have an effect on the climate in remote areas, a phenomenon that is often referred to as teleconnection. Because changes in local climate immediately affect terrestrial ecosystems through a series of complex processes, ocean-atmospheric oscillations are expected to influence land evaporation; i.e. the return flux of water from land into the atmosphere. In this presentation, the effects of ocean-atmospheric oscillations on global terrestrial evaporation are analysed. We use multi-decadal, satellite-based observations of different climate variables (air temperature, radiation, precipitation) in combination with a simple supervised learning method - the Least Absolute Shrinkage and Selection Operator - to detect the impact of sixteen leading ocean-atmospheric oscillations on terrestrial evaporation. The latter is retrieved using the Global Land Evaporation Amsterdam Model (GLEAM). The analysis reveals hotspot regions in which more than 30% of the inter-annual variability in terrestrial evaporation can be explained by ocean-atmospheric oscillations. The impact is different per region and season, and can typically be attributed to a small subset of oscillations. For instance, the dynamics in terrestrial evaporation over eastern Australia are substantially impacted by both the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) during Austral spring. Using the same learning method, but targeting terrestrial evaporation based on its local climatic drivers (air temperature, precipitation, and radiation), shows the dominant control of precipitation on terrestrial evaporation in Australia, suggesting that both ENSO and IOD affect the precipitation, in his turn influencing evaporation. The latter is confirmed by regressing precipitation to the ocean-atmospheric oscillations. The results of our study allow for a better understanding of the link between ocean-atmosphere dynamics and terrestrial bio-geochemical cycles, and may help improve the prediction of future changes in the water cycle over the continents.

Multifractal Detrended Fluctuation Analysis of Regional Precipitation Sequences Based on the CEEMDAN-WPT

NASA Astrophysics Data System (ADS)

Liu, Dong; Cheng, Chen; Fu, Qiang; Liu, Chunlei; Li, Mo; Faiz, Muhammad Abrar; Li, Tianxiao; Khan, Muhammad Imran; Cui, Song

2018-03-01

In this paper, the complete ensemble empirical mode decomposition with the adaptive noise (CEEMDAN) algorithm is introduced into the complexity research of precipitation systems to improve the traditional complexity measure method specific to the mode mixing of the Empirical Mode Decomposition (EMD) and incomplete decomposition of the ensemble empirical mode decomposition (EEMD). We combined the CEEMDAN with the wavelet packet transform (WPT) and multifractal detrended fluctuation analysis (MF-DFA) to create the CEEMDAN-WPT-MFDFA, and used it to measure the complexity of the monthly precipitation sequence of 12 sub-regions in Harbin, Heilongjiang Province, China. The results show that there are significant differences in the monthly precipitation complexity of each sub-region in Harbin. The complexity of the northwest area of Harbin is the lowest and its predictability is the best. The complexity and predictability of the middle and Midwest areas of Harbin are about average. The complexity of the southeast area of Harbin is higher than that of the northwest, middle, and Midwest areas of Harbin and its predictability is worse. The complexity of Shuangcheng is the highest and its predictability is the worst of all the studied sub-regions. We used terrain and human activity as factors to analyze the causes of the complexity of the local precipitation. The results showed that the correlations between the precipitation complexity and terrain are obvious, and the correlations between the precipitation complexity and human influence factors vary. The distribution of the precipitation complexity in this area may be generated by the superposition effect of human activities and natural factors such as terrain, general atmospheric circulation, land and sea location, and ocean currents. To evaluate the stability of the algorithm, the CEEMDAN-WPT-MFDFA was compared with the equal probability coarse graining LZC algorithm, fuzzy entropy, and wavelet entropy. The results show that the CEEMDAN-WPT-MFDFA was more stable than 3 contrast methods under the influence of white noise and colored noise, which proves that the CEEMDAN-WPT-MFDFA has a strong robustness under the influence of noise.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Min; Kollias, Pavlos; Feng, Zhe

The motivation for this research is to develop a precipitation classification and rain rate estimation method using cloud radar-only measurements for Atmospheric Radiation Measurement (ARM) long-term cloud observation analysis, which are crucial and unique for studying cloud lifecycle and precipitation features under different weather and climate regimes. Based on simultaneous and collocated observations of the Ka-band ARM zenith radar (KAZR), two precipitation radars (NCAR S-PolKa and Texas A&M University SMART-R), and surface precipitation during the DYNAMO/AMIE field campaign, a new cloud radar-only based precipitation classification and rain rate estimation method has been developed and evaluated. The resulting precipitation classification ismore » equivalent to those collocated SMART-R and S-PolKa observations. Both cloud and precipitation radars detected about 5% precipitation occurrence during this period. The convective (stratiform) precipitation fraction is about 18% (82%). The 2-day collocated disdrometer observations show an increased number concentration of large raindrops in convective rain compared to dominant concentration of small raindrops in stratiform rain. The composite distributions of KAZR reflectivity and Doppler velocity also show two distinct structures for convective and stratiform rain. These indicate that the method produces physically consistent results for two types of rain. The cloud radar-only rainfall estimation is developed based on the gradient of accumulative radar reflectivity below 1 km, near-surface Ze, and collocated surface rainfall (R) measurement. The parameterization is compared with the Z-R exponential relation. The relative difference between estimated and surface measured rainfall rate shows that the two-parameter relation can improve rainfall estimation.« less

Modelling probabilities of heavy precipitation by regional approaches

NASA Astrophysics Data System (ADS)

Gaal, L.; Kysely, J.

2009-09-01

Extreme precipitation events are associated with large negative consequences for human society, mainly as they may trigger floods and landslides. The recent series of flash floods in central Europe (affecting several isolated areas) on June 24-28, 2009, the worst one over several decades in the Czech Republic as to the number of persons killed and the extent of damage to buildings and infrastructure, is an example. Estimates of growth curves and design values (corresponding e.g. to 50-yr and 100-yr return periods) of precipitation amounts, together with their uncertainty, are important in hydrological modelling and other applications. The interest in high quantiles of precipitation distributions is also related to possible climate change effects, as climate model simulations tend to project increased severity of precipitation extremes in a warmer climate. The present study compares - in terms of Monte Carlo simulation experiments - several methods to modelling probabilities of precipitation extremes that make use of ‘regional approaches’: the estimation of distributions of extremes takes into account data in a ‘region’ (‘pooling group’), in which one may assume that the distributions at individual sites are identical apart from a site-specific scaling factor (the condition is referred to as ‘regional homogeneity’). In other words, all data in a region - often weighted in some way - are taken into account when estimating the probability distribution of extremes at a given site. The advantage is that sampling variations in the estimates of model parameters and high quantiles are to a large extent reduced compared to the single-site analysis. We focus on the ‘region-of-influence’ (ROI) method which is based on the identification of unique pooling groups (forming the database for the estimation) for each site under study. The similarity of sites is evaluated in terms of a set of site attributes related to the distributions of extremes. The issue of the size of the region is linked with a built-in test on regional homogeneity of data. Once a pooling group is delineated, weights based on a dissimilarity measure are assigned to individual sites involved in a pooling group, and all (weighted) data are employed in the estimation of model parameters and high quantiles at a given location. The ROI method is compared with the Hosking-Wallis (HW) regional frequency analysis, which is based on delineating fixed regions (instead of flexible pooling groups) and assigning unit weights to all sites in a region. The comparison of the performance of the individual regional models makes use of data on annual maxima of 1-day precipitation amounts at 209 stations covering the Czech Republic, with altitudes ranging from 150 to 1490 m a.s.l. We conclude that the ROI methodology is superior to the HW analysis, particularly for very high quantiles (100-yr return values). Another advantage of the ROI approach is that subjective decisions - unavoidable when fixed regions in the HW analysis are formed - may efficiently be suppressed, and almost all settings of the ROI method may be justified by results of the simulation experiments. The differences between (any) regional method and single-site analysis are very pronounced and suggest that the at-site estimation is highly unreliable. The ROI method is then applied to estimate high quantiles of precipitation amounts at individual sites. The estimates and their uncertainty are compared with those from a single-site analysis. We focus on the eastern part of the Czech Republic, i.e. an area with complex orography and a particularly pronounced role of Mediterranean cyclones in producing precipitation extremes. The design values are compared with precipitation amounts recorded during the recent heavy precipitation events, including the one associated with the flash flood on June 24, 2009. We also show that the ROI methodology may easily be transferred to the analysis of precipitation extremes in climate model outputs. It efficiently reduces (random) variations in the estimates of parameters of the extreme value distributions in individual gridboxes that result from large spatial variability of heavy precipitation, and represents a straightforward tool for ‘weighting’ data from neighbouring gridboxes within the estimation procedure. The study is supported by the Grant Agency of AS CR under project B300420801.

Method for inhibiting silica precipitation and scaling in geothermal flow systems

DOEpatents

Harrar, Jackson E.; Lorensen, Lyman E.; Locke, Frank E.

1982-01-01

A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds.

Evaluation of Fuzzy-Logic Framework for Spatial Statistics Preserving Methods for Estimation of Missing Precipitation Data

NASA Astrophysics Data System (ADS)

El Sharif, H.; Teegavarapu, R. S.

2012-12-01

Spatial interpolation methods used for estimation of missing precipitation data at a site seldom check for their ability to preserve site and regional statistics. Such statistics are primarily defined by spatial correlations and other site-to-site statistics in a region. Preservation of site and regional statistics represents a means of assessing the validity of missing precipitation estimates at a site. This study evaluates the efficacy of a fuzzy-logic methodology for infilling missing historical daily precipitation data in preserving site and regional statistics. Rain gauge sites in the state of Kentucky, USA, are used as a case study for evaluation of this newly proposed method in comparison to traditional data infilling techniques. Several error and performance measures will be used to evaluate the methods and trade-offs in accuracy of estimation and preservation of site and regional statistics.

Application of zinc chloride precipitation method for rapid isolation and concentration of infectious Pectobacterium spp. and Dickeya spp. lytic bacteriophages from surface water and plant and soil extracts.

PubMed

Czajkowski, Robert; Ozymko, Zofia; Lojkowska, Ewa

2016-01-01

This is the first report describing precipitation of bacteriophage particles with zinc chloride as a method of choice to isolate infectious lytic bacteriophages against Pectobacterium spp. and Dickeya spp. from environmental samples. The isolated bacteriophages are ready to use to study various (ecological) aspects of bacteria-bacteriophage interactions. The method comprises the well-known precipitation of phages from aqueous extracts of the test material by addition of ZnCl2, resuscitation of bacteriophage particles in Ringer's buffer to remove the ZnCl2 excess and a soft agar overlay assay with the host bacterium to isolate infectious individual phage plaques. The method requires neither an enrichment step nor other steps (e. g., PEG precipitation, ultrafiltration, or ultracentrifugation) commonly used in other procedures and results in isolation of active viable bacteriophage particles.

Evaluation of effects of changes in canal management and precipitation patterns on salinity in Biscayne Bay, Florida, using an integrated surface-water/groundwater model

USGS Publications Warehouse

Lohmann, Melinda A.; Swain, Eric D.; Wang, John D.; Dixon, Joann

2012-01-01

Biscayne National Park, located in Biscayne Bay in southeast Florida, is one of the largest marine parks in the country and sustains a large natural marine fishery where numerous threatened and endangered species reproduce. In recent years, the bay has experienced hypersaline conditions (salinity greater than 35 practical salinity units) of increasing magnitude and duration. Hypersalinity events were particularly pronounced during April to August 2004 in nearshore areas along the southern and middle parts of the bay. Prolonged hypersaline conditions can cause degradation of water quality and permanent damage to, or loss of, brackish nursery habitats for multiple species of fish and crustaceans as well as damage to certain types of seagrasses that are not tolerant of extreme changes in salinity. To evaluate the factors that contribute to hypersalinity events and to test the effects of possible changes in precipitation patterns and canal flows into Biscayne Bay on salinity in the bay, the U.S. Geological Survey constructed a coupled surface-water/groundwater numerical flow model. The model is designed to account for freshwater flows into Biscayne Bay through the canal system, leakage of salty bay water into the underlying Biscayne aquifer, discharge of fresh and salty groundwater from the Biscayne aquifer into the bay, direct effects of precipitation on bay salinity, indirect effects of precipitation on recharge to the Biscayne aquifer, direct effects of evapotranspiration (ET) on bay salinity, indirect effects of ET on recharge to the Biscayne aquifer, and maintenance of mass balance of both water and solute. The model was constructed using the Flow and Transport in a Linked Overland/Aquifer Density Dependent System (FTLOADDS) simulator, version 3.3, which couples the two-dimensional, surface-water flow and solute-transport simulator SWIFT2D with the density-dependent, groundwater flow an solute-transport simulator SEAWAT. The model was calibrated by a trial-and-error method to fit observed groundwater heads, estimated base flow, and measured bay salinity and temperatures from 1996 to 2004, as well as the location of the freshwater-saltwater interface in the aquifer, by adjusting ET rate limiters, canal vertical hydraulic conductance, leakage rate coefficients (transition-layer thickness and hydraulic conductivity), Manning's n value, and delineation of rainfall zones. Although flow budget calculations indicate that precipitation, ET, and groundwater flux into the bay represent a small portion of the overall budget, these factors may be important in controlling salinity in some parts of the bay, for example the southern parts of the bay where the canal system is not extensively developed or controlled. The balance of precipitation and ET during the wet season generally results in a reduction of bay salinity, whereas the balance of precipitation and ET during the dry season generally results in an increase in bay salinity. During years when wet season precipitation is lower than average, for example less than 70 percent total precipitation for an average year, ET could outweigh precipitation over the bay for essentially the entire year. Hypersaline conditions are prone to occur near the end of the dry season because precipitation rates are generally lower, canal discharge rates (which are strongly correlated to precipitation rates) are also generally lower, and ET rates are higher than during the rest of the year. The hypersalinity event of 2004 followed several years of relatively low precipitation and correspondingly reduced canal structure releases and was unusually extensive, continuing into July. Thus, hypersalinity is ultimately the result of a cumulative deficit of precipitation. The model was used to test the effects of possible changes in canal flux and precipitation. Simulation results showed that by increasing, reducing, or modifying canal discharge rates, the effects on salinity in the bay were more pronounced in the northern part of the bay where there are more canals and canal-control structures. By doubling and halving precipitation, the effects on bay salinity were more pronounced in the southern part of the bay than in the northern part of the bay where there are fewer canals and canal-control structures. The model is designed to quantify factors that contribute to hypersaline conditions in Biscayne Bay and may be less appropriate for addressing other issues or examining conditions substantially different from those described in this report. Model results must be interpreted in light of model limitations, which include representation of the system and conceptual model, uncertainty in physical properties used to describe the system or processes, the scale and discretization of the system, and representation of the boundary conditions.

Carrier free immobilization and characterization of trypsin.

PubMed

Menfaatli, Esra; Zihnioglu, Figen

2015-04-01

Pancreatic trypsin was immobilized by cross-linked enzyme aggregates (CLEA) which is a carrier free immobilization method. Ammonium sulfate was chosen for enzyme precipitation which was followed by cross linking of formed aggregates via glutaraldehyde. Concentrations of precipitant and cross linker were respectively optimized as 60% ammonium sulfate and 1% glutaraldehyde. Optimum pH and temperature for CLEA was increased compared to free enzyme. Furthermore, pH, thermal and storage stability were improved. Presence of additives had no effects on enzyme activity. Prepared cross-linked trypsin aggregates are convenient for in situ protein fragmentation and can be used for protein identification.

Kinetics of the isothermal decomposition of zirconium hydride: terminal solid solubility for precipitation and dissolution

NASA Astrophysics Data System (ADS)

Denisov, E. A.; Kompaniets, T. N.; Voyt, A. P.

2018-05-01

The hydrogen permeation technique in the surface-limited regime (SLR) was first used to study the isothermal decomposition of zirconium hydride. It is shown that under isothermal conditions, the hydrogen terminal solid solubility in the α-phase for hydride precipitation (TSSp) and dissolution (TSSd) differ only by 6%, in contrast to the 20-30% indicated in the available literature. It is demonstrated that even the minimum heating/cooling rate (1 C/min) used in the traditional methods of studying TSSp and TSSd is too high to exclude the effect of kinetics on the results obtained.

A data centred method to estimate and map how the local distribution of daily precipitation is changing

NASA Astrophysics Data System (ADS)

Chapman, Sandra; Stainforth, David; Watkins, Nick

2014-05-01

Estimates of how our climate is changing are needed locally in order to inform adaptation planning decisions. This requires quantifying the geographical patterns in changes at specific quantiles in distributions of variables such as daily temperature or precipitation. Here we focus on these local changes and on a method to transform daily observations of precipitation into patterns of local climate change. We develop a method[1] for analysing local climatic timeseries to assess which quantiles of the local climatic distribution show the greatest and most robust changes, to specifically address the challenges presented by daily precipitation data. We extract from the data quantities that characterize the changes in time of the likelihood of daily precipitation above a threshold and of the relative amount of precipitation in those days. Our method is a simple mathematical deconstruction of how the difference between two observations from two different time periods can be assigned to the combination of natural statistical variability and/or the consequences of secular climate change. This deconstruction facilitates an assessment of how fast different quantiles of precipitation distributions are changing. This involves both determining which quantiles and geographical locations show the greatest change but also, those at which any change is highly uncertain. We demonstrate this approach using E-OBS gridded data[2] timeseries of local daily precipitation from specific locations across Europe over the last 60 years. We treat geographical location and precipitation as independent variables and thus obtain as outputs the pattern of change at a given threshold of precipitation and with geographical location. This is model- independent, thus providing data of direct value in model calibration and assessment. Our results show regionally consistent patterns of systematic increase in precipitation on the wettest days, and of drying across all days which is of potential value in adaptation planning. [1] S C Chapman, D A Stainforth, N W Watkins, 2013, On Estimating Local Long Term Climate Trends, Phil. Trans. R. Soc. A, 371 20120287; D. A. Stainforth, 2013, S. C. Chapman, N. W. Watkins, Mapping climate change in European temperature distributions, Environ. Res. Lett. 8, 034031 [2] Haylock, M.R., N. Hofstra, A.M.G. Klein Tank, E.J. Klok, P.D. Jones and M. New. 2008: A European daily high-resolution gridded dataset of surface temperature and precipitation. J. Geophys. Res (Atmospheres), 113, D20119

Multi-model analysis of precipitation-related climatological extremes for the Carpathian Region

NASA Astrophysics Data System (ADS)

Kis, Anna; Pongracz, Rita; Bartholy, Judit

2015-04-01

As a consequence of global climate change, both frequency and intensity of climatological and meteorological extremes are likely to change. These will certainly further induce various effects on hydrological extremes. Although more frequent hot weather in summer and overall warmer climatic conditions compared to the past decades are quite straightforward direct consequences of global warming, the effects on precipitation might be less clear because the higher spatial and temporal variabilities might hide robust changing signals. Nevertheless, precipitation is one of the most important meteorological variables since it considerably affects natural ecosystems and cultivated vegetation as well, as most of human activities. Extreme precipitation events - both excessive, intense rainfalls and severe droughts - may result in severe environmental, agricultural, and economical disasters. For instance, excessive precipitation may induce floods, flash-floods, landslides, traffic accidents. On the other hand, the lack of precipitation for extended period and coincidental intense heat wave often lead to severe drought events, which certainly affect agricultural production negatively, and hence, food safety might also be threatened. In order to avoid or at least reduce the effects of these precipitation-related hazards, national and local communities need to develop regional adaptation strategies, and then, act according to them. For this purpose, climatological projections are needed as a scientific basis. Coarse resolution results of global climate model (GCM) simulations must be downscaled to regional and local scales, hence better serving decision-makers' and end-users' needs. Dynamical downscaling technique applies regional climate model (RCM) to provide fine resolution climatological estimations for the future. Thus, in this study 11 completed RCM simulations with 25 km horizontal resolution are used from the ENSEMBLES database taking into account SRES A1B scenario for the 21st century. Before the thorough analysis of several drought- and precipitation-related climate indices (i.e., describing drought events, or intensity of precipitation exceeding different percentile-based or absolute threshold values, respectively), a percentile-based bias correction method was applied to the raw RCM output data, for which the homogenized daily gridded CarpatClim database (1961-2010) served as a reference. Absolute and relative seasonal mean changes of the climate indices are calculated for two future time periods (2021-2050 and 2071-2100) and for three subregions (i.e., Slovakia, Hungary, and Romania) within the entire Carpathian Region. According to our results, longer dry periods are estimated for the summer season, mainly in the southern parts of the domain, while precipitation intensity is likely to increase. Heavy precipitation days and high percentile values are projected to increase in the Carpathian Region, especially, in winter and autumn.

Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara

NASA Astrophysics Data System (ADS)

Kemena, Tronje Peer; Matthes, Katja; Martin, Thomas; Wahl, Sebastian; Oschlies, Andreas

2017-09-01

Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR's CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.

Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara

NASA Astrophysics Data System (ADS)

Kemena, Tronje Peer; Matthes, Katja; Martin, Thomas; Wahl, Sebastian; Oschlies, Andreas

2018-06-01

Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR's CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.

Precipitation Effects on Microbial Pollution in a River: Lag Structures and Seasonal Effect Modification

PubMed Central

Tornevi, Andreas; Bergstedt, Olof; Forsberg, Bertil

2014-01-01

Background The river Göta Älv is a source of freshwater for 0.7 million swedes. The river is subject to contamination from sewer systems discharge and runoff from agricultural lands. Climate models projects an increase in precipitation and heavy rainfall in this region. This study aimed to determine how daily rainfall causes variation in indicators of pathogen loads, to increase knowledge of variations in river water quality and discuss implications for risk management. Methods Data covering 7 years of daily monitoring of river water turbidity and concentrations of E. coli, Clostridium and coliforms were obtained, and their short-term variations in relation with precipitation were analyzed with time series regression and non-linear distributed lag models. We studied how precipitation effects varied with season and compared different weather stations for predictive ability. Results Generally, the lowest raw water quality occurs 2 days after rainfall, with poor raw water quality continuing for several more days. A rainfall event of >15 mm/24-h (local 95 percentile) was associated with a three-fold higher concentration of E. coli and 30% higher turbidity levels (lag 2). Rainfall was associated with exponential increases in concentrations of indicator bacteria while the effect on turbidity attenuated with very heavy rainfall. Clear associations were also observed between consecutive days of wet weather and decreased water quality. The precipitation effect on increased levels of indicator bacteria was significant in all seasons. Conclusions Rainfall elevates microbial risks year-round in this river and freshwater source and acts as the main driver of varying water quality. Heavy rainfall appears to be a better predictor of fecal pollution than water turbidity. An increase of wet weather and extreme events with climate change will lower river water quality even more, indicating greater challenges for drinking water producers, and suggesting better control of sources of pollution. PMID:24874010

A multi-source precipitation approach to fill gaps over a radar precipitation field

NASA Astrophysics Data System (ADS)

Tesfagiorgis, K. B.; Mahani, S. E.; Khanbilvardi, R.

2012-12-01

Satellite Precipitation Estimates (SPEs) may be the only available source of information for operational hydrologic and flash flood prediction due to spatial limitations of radar and gauge products. The present work develops an approach to seamlessly blend satellite, radar, climatological and gauge precipitation products to fill gaps over ground-based radar precipitation fields. To mix different precipitation products, the bias of any of the products relative to each other should be removed. For bias correction, the study used an ensemble-based method which aims to estimate spatially varying multiplicative biases in SPEs using a radar rainfall product. Bias factors were calculated for a randomly selected sample of rainy pixels in the study area. Spatial fields of estimated bias were generated taking into account spatial variation and random errors in the sampled values. A weighted Successive Correction Method (SCM) is proposed to make the merging between error corrected satellite and radar rainfall estimates. In addition to SCM, we use a Bayesian spatial method for merging the gap free radar with rain gauges, climatological rainfall sources and SPEs. We demonstrate the method using SPE Hydro-Estimator (HE), radar- based Stage-II, a climatological product PRISM and rain gauge dataset for several rain events from 2006 to 2008 over three different geographical locations of the United States. Results show that: the SCM method in combination with the Bayesian spatial model produced a precipitation product in good agreement with independent measurements. The study implies that using the available radar pixels surrounding the gap area, rain gauge, PRISM and satellite products, a radar like product is achievable over radar gap areas that benefits the scientific community.

Sensitivity of snow process simulations to precipitation-phase transition method in forested and open areas

NASA Astrophysics Data System (ADS)

Lundberg, A.; Gustafsson, D.

2009-04-01

Modeling of forest snow processes is complicated and especially problematic seems to be the separation of precipitation phase in climates where a large part of the precipitation falls at temperatures near zero degrees Celsius. When the precipitation is classified as snow, the tree crowns can carry an order of magnitude more canopy storage as compared to when the precipitation is classified as rain, and snow in the trees also alters the albedo of the forest while rain does not. Many different schemes for the precipitation phase separation are used by various snow models. Some models use just one air temperature threshold (TR/S) below which all precipitation is assumed to be snow and above which all precipitation is classified as rain. A more common approach for forest snow models is to use two temperature thresholds. The snow fraction (SF) is then set to one below the snow threshold (TS) and to zero above the rain threshold (TR) and SF is assumed to decrease linearly between these two thresholds. Also more sophisticated schemes exist, but three seems to be a lack of agreement on how the precipitation phase separations should be performed. The aim with this study is to use a hydrological model including canopy snow processes to illustrate the sensitivity for different formulations of the precipitation phase separation on a) the simulated maximum snow pack storage b) the interception evaporation loss and c) snow melt runoff. In other words, to investigate of the choice of precipitation phase separation has an impact on the simulated wintertime water balance. Simulations are made for sites in different climates and for both open fields and forest sites in different regions of Sweden from north to south. In general, precipitation phase separation methods that classified snowfall at higher temperatures resulted in a larger proportion of the precipitation lost by interception evaporation as a result of the increased interception capacity. However, the maximum snow accumulation was also increased in some cases due to the overall increased snowfall, depending on canopy density and precipitation and temperature regimes. Results show that the choice of precipitation phase separation method can have an significant impact on the simulated wintertime water balance, especially in forested regions.

Monitoring of Typical Steppe Desertification Based on Time Series of Net Primary Productivity Data

NASA Astrophysics Data System (ADS)

Wang, Hongyan; Li, Qiangzi; Gao, Zhihai

2014-11-01

Monitoring of grassland condition is a basic prerequisite for finding the degradation of a territory under climatic and human pressures leading to desertification. The temporal change in vegetation productivity is a key indicator of grassland degradation. In this paper, taking the Xilin Gol League as a case, the net primary production (NPP) dynamic trends during 2001-2010 were analyzed, with the Mann-Kendall test. In this paper, in the study area where precipitation and NPP has significantly positive correlation, the residual trend method (RESTREND) was used to remove the annual NPP fluctuation caused by rainfall fluctuation and reduce the effect of precipitation on vegetation monitoring indicators. The results showed that An overall strong liner correlation between NPP and precipitation was observed in the Xilin Gol grassland, with 68.52% of the pixels analyzed being significantly correlated (α =0.1). The statistical analysis reveals that the NPP trend estimation generally shows a decreasing trend, with 13.02% of the Xilin Gol grassland being analyzed showing a significant trend (11.47% decrease and 1.55% increase). However, the Xilin Gol grassland desertification was not serious in the past ten years, only 5.16% of the study area where the vegetation productivity was significantly decreases (reducing the effect of precipitation).

Determination of Lead in Blood by Atomic Absorption Spectrophotometry1

PubMed Central

Selander, Stig; Cramér, Kim

1968-01-01

Lead in blood was determined by atomic absorption spectrophotometry, using a wet ashing procedure and a procedure in which the proteins were precipitated with trichloroacetic acid. In both methods the lead was extracted into isobutylmethylketone before measurement, using ammonium pyrrolidine dithiocarbamate as chelator. The simpler precipitation procedure was shown to give results identical with those obtained with the ashing technique. In addition, blood specimens were examined by the precipitation method and by spectral analysis, which method includes wet ashing of the samples, with good agreement. All analyses were done on blood samples from `normal' persons or from lead-exposed workers, and no additions of inorganic lead were made. The relatively simple protein precipitation technique gave accurate results and is suitable for the large-scale control of lead-exposed workers. PMID:5663425

A review of statistical methods to analyze extreme precipitation and temperature events in the Mediterranean region

NASA Astrophysics Data System (ADS)

Lazoglou, Georgia; Anagnostopoulou, Christina; Tolika, Konstantia; Kolyva-Machera, Fotini

2018-04-01

The increasing trend of the intensity and frequency of temperature and precipitation extremes during the past decades has substantial environmental and socioeconomic impacts. Thus, the objective of the present study is the comparison of several statistical methods of the extreme value theory (EVT) in order to identify which is the most appropriate to analyze the behavior of the extreme precipitation, and high and low temperature events, in the Mediterranean region. The extremes choice was made using both the block maxima and the peaks over threshold (POT) technique and as a consequence both the generalized extreme value (GEV) and generalized Pareto distributions (GPDs) were used to fit them. The results were compared, in order to select the most appropriate distribution for extremes characterization. Moreover, this study evaluates the maximum likelihood estimation, the L-moments and the Bayesian method, based on both graphical and statistical goodness-of-fit tests. It was revealed that the GPD can characterize accurately both precipitation and temperature extreme events. Additionally, GEV distribution with the Bayesian method is proven to be appropriate especially for the greatest values of extremes. Another important objective of this investigation was the estimation of the precipitation and temperature return levels for three return periods (50, 100, and 150 years) classifying the data into groups with similar characteristics. Finally, the return level values were estimated with both GEV and GPD and with the three different estimation methods, revealing that the selected method can affect the return level values for both the parameter of precipitation and temperature.

Comparison of Analytical Methods for the Determination of Uranium in Seawater Using Inductively Coupled Plasma Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, Jordana R.; Gill, Gary A.; Kuo, Li-Jung

2016-04-20

Trace element determinations in seawater by inductively coupled plasma mass spectrometry are analytically challenging due to the typically very low concentrations of the trace elements and the potential interference of the salt matrix. In this study, we did a comparison for uranium analysis using inductively coupled plasma mass spectrometry (ICP-MS) of Sequim Bay seawater samples and three seawater certified reference materials (SLEW-3, CASS-5 and NASS-6) using seven different analytical approaches. The methods evaluated include: direct analysis, Fe/Pd reductive precipitation, standard addition calibration, online automated dilution using an external calibration with and without matrix matching, and online automated pre-concentration. The methodmore » which produced the most accurate results was the method of standard addition calibration, recovering uranium from a Sequim Bay seawater sample at 101 ± 1.2%. The on-line preconcentration method and the automated dilution with matrix-matched calibration method also performed well. The two least effective methods were the direct analysis and the Fe/Pd reductive precipitation using sodium borohydride« less

Selection of an Appropriate Protein Extraction Method to Study the Phosphoproteome of Maize Photosynthetic Tissue

PubMed Central

Luís, Inês M.; Alexandre, Bruno M.; Oliveira, M. Margarida

2016-01-01

Often plant tissues are recalcitrant and, due to that, methods relying on protein precipitation, such as TCA/acetone precipitation and phenol extraction, are usually the methods of choice for protein extraction in plant proteomic studies. However, the addition of precipitation steps to protein extraction methods may negatively impact protein recovery, due to problems associated with protein re-solubilization. Moreover, we show that when working with non-recalcitrant plant tissues, such as young maize leaves, protein extraction methods with precipitation steps compromise the maintenance of some labile post-translational modifications (PTMs), such as phosphorylation. Therefore, a critical issue when studying PTMs in plant proteins is to ensure that the protein extraction method is the most appropriate, both at qualitative and quantitative levels. In this work, we compared five methods for protein extraction of the C4-photosynthesis related proteins, in the tip of fully expanded third-leaves. These included: TCA/Acetone Precipitation; Phenol Extraction; TCA/Acetone Precipitation followed by Phenol Extraction; direct extraction in Lysis Buffer (a urea-based buffer); and direct extraction in Lysis Buffer followed by Cleanup with a commercial kit. Protein extraction in Lysis Buffer performed better in comparison to the other methods. It gave one of the highest protein yields, good coverage of the extracted proteome and phosphoproteome, high reproducibility, and little protein degradation. This was also the easiest and fastest method, warranting minimal sample handling. We also show that this method is adequate for the successful extraction of key enzymes of the C4-photosynthetic metabolism, such as PEPC, PPDK, PEPCK, and NADP-ME. This was confirmed by MALDI-TOF/TOF MS analysis of excised spots of 2DE analyses of the extracted protein pools. Staining for phosphorylated proteins in 2DE revealed the presence of several phosphorylated isoforms of PEPC, PPDK, and PEPCK. PMID:27727304

Method for inhibiting silica precipitation and scaling in geothermal flow systems

DOEpatents

Harrar, J.E.; Lorensen, L.E.; Locke, F.E.

1980-06-13

A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds is described.

METHOD OF PREPARING PROTACTINIUM VALUES

DOEpatents

Katzin, L.I.; Larson, R.G.; Thompson, R.C.; Van Winkle, Q.

1959-05-19

Separation and purification from initial acid leaches of pitchblende of Pa is described. This supernatant acid solution is treated with alkali metal carbonates to precipitate Pa. Silica is removed from the precipitate by hydroxide treatment. The Pa residue is dissolved in HNO/sub 3/ and Pa is concentrated by cyclic precipitations with MnO/sub 2/. The last solution is hydrolyzed to precipitate Pa. The Pa precipitate contains Ti and Zr which are removed by ion exchange. (T.R.H.)

Monitoring Rainfall by Combining Ground-based Observed Precipitation and PERSIANN Satellite Product (Case Study Area: Lake Urmia Basin)

NASA Astrophysics Data System (ADS)

Abrishamchi, A.; Mirshahi, A.

2015-12-01

The global coverage, quick access, and appropriate spatial-temporal resolution of satellite precipitation data renders the data appropriate for hydrologic studies, especially in regions with no sufficient rain-gauge network. On the other hand, satellite precipitation products may have major errors. The present study aims at reduction of estimation error of the PERSIANN satellite precipitation product. Bayesian logic employed to develop a statistical relationship between historical ground-based and satellite precipitation data. This relationship can then be used to reduce satellite precipitation product error in near real time, when there is no ground-based precipitation observation. The method was evaluated in the Lake Urmia basin with a monthly time scale; November to May of 2000- 2008 for the purpose of model development and two years of 2009 and 2010 for the validation of the established relationships. Moreover, Kriging interpolation method was employed to estimate the average rainfall in the basin. Furthermore, to downscale the satellite precipitation product from 0.25o to 0.05o, data-location downscaling algorithm was used. In 76 percent of months, the final product, compared with the satellite precipitation, had less error during the validation period. Additionally, its performance was marginally better than adjusted PERSIANN product.

A GIS Tool for evaluating and improving NEXRAD and its application in distributed hydrologic modeling

NASA Astrophysics Data System (ADS)

Zhang, X.; Srinivasan, R.

2008-12-01

In this study, a user friendly GIS tool was developed for evaluating and improving NEXRAD using raingauge data. This GIS tool can automatically read in raingauge and NEXRAD data, evaluate the accuracy of NEXRAD for each time unit, implement several geostatistical methods to improve the accuracy of NEXRAD through raingauge data, and output spatial precipitation map for distributed hydrologic model. The geostatistical methods incorporated in this tool include Simple Kriging with varying local means, Kriging with External Drift, Regression Kriging, Co-Kriging, and a new geostatistical method that was newly developed by Li et al. (2008). This tool was applied in two test watersheds at hourly and daily temporal scale. The preliminary cross-validation results show that incorporating raingauge data to calibrate NEXRAD can pronouncedly change the spatial pattern of NEXRAD and improve its accuracy. Using different geostatistical methods, the GIS tool was applied to produce long term precipitation input for a distributed hydrologic model - Soil and Water Assessment Tool (SWAT). Animated video was generated to vividly illustrate the effect of using different precipitation input data on distributed hydrologic modeling. Currently, this GIS tool is developed as an extension of SWAT, which is used as water quantity and quality modeling tool by USDA and EPA. The flexible module based design of this tool also makes it easy to be adapted for other hydrologic models for hydrological modeling and water resources management.

X-ray studies of dynamic aging in an aluminum alloy subjected to severe plastic deformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitdikov, V.D., E-mail: svil@mail.rb.ru; Laboratory for Mechanics of Bulk Nanomaterials, Saint Petersburg State University, 28 Universitetsky pr., Saint Petersburg 198504; Chizhov, P.S.

In this work, X-ray scattering methods were applied for a quantitative characterization of the microstructure of an aluminum alloy of the Al–Mg–Si system during dynamic aging realized through the high pressure torsion technique. A qualitative and quantitative phase analysis of the alloy was performed, together with Al alloy lattice parameter determination. From the reflections broadening the effective size of the coherent scattering domains and the lattice microstrain were determined in the framework of the Halder–Wagner approach. Using the method of small-angle X-ray scattering, the quantitative characteristics of the size, shape and spatial distribution of the secondary phase particles formed inmore » the Al alloy during dynamic aging were established. In order to validate the obtained results, the method of small-angle X-ray scattering was preliminarily tested on similar samples after artificial aging and compared with the results from small-angle neutron diffraction widely known in literature. - Highlights: • Spherical fcc β-Mg2Si precipitates formed in Al 6201 alloy during dynamic aging in the course of severe plastic deformation. • The size, shape and distribution of the precipitates due to artificial and dynamic aging were revealed by SAXS method. • Monoclinic needle-like β' precipitates and Al5FeSi intermetallic phase were detected in 6201 alloy after T6 treatment.« less

Method to Remove Particulate Matter from Dusty Gases at Low Pressures

NASA Technical Reports Server (NTRS)

Calle, Carlos; Clements, J. Sid

2012-01-01

Future human exploration of Mars will rely on local Martian resources to reduce the mass, cost, and risk of space exploration launched from Earth. NASA's In Situ Resource Utilization (ISRU) Project seeks to produce mission consumables from local Martian resources, such as atmospheric gas. The Martian atmosphere, however, contains dust particles in the 2-to-10 -micrometer range. These dust particles must be removed before the Martian atmospheric gas can be processed. The low pressure of the Martian atmosphere, at 5 to 10 mbars, prevents the development of large voltages required for a standard electrostatic precipitator. If the voltage is increased too much, the corona transitions into a glow/streamer discharge unsuitable for the operation of a precipitator. If the voltage is not large enough, the dust particles are not sufficiently charged and the field is not strong enough to drive the particles to the collector. A method using electrostatic fields has been developed to collect dust from gaseous environments at low pressures, specifically carbon dioxide at pressures around 5 to 10 mbars. This method, commonly known as electrostatic precipitation, is a mature technology in air at one atmosphere. In this case, the high voltages required for the method to work can easily be achieved. However, in carbon dioxide at low pressures, such as those found on Mars, large voltages are not possible. The innovation reported here consists of two concentric cylindrical electrodes set at specific potential difference that generate an electric field that produces a corona capable of imparting an electrostatic charge to the incoming dust particles. The strength of the field is carefully balanced so as to produce a stable charging corona at 5 to 10 mbars, and is also capable of imparting a force to the particles that drives them to the collecting electrode. There are only two possible ways that dust can be removed from Martian atmospheric gas intakes: with this electrostatic precipitator design, and with the use of filters. However, filters require upstream compression of the gas to be treated because the atmospheric pressure on Mars is too close to vacuum to use a vacuum pump downstream to the filter to draw the gas through the filter. The electrostatic precipitator is the best and more efficient solution for this environment. No other precipitator designs have been developed for the environment of Mars due to the challenges of the low atmospheric pressure. Dust particles are charged using corona generation around the high-voltage discharge electrode, which ionizes gas molecules. Since the atmospheric gas intakes for the ISRU processing chambers will likely be cylindrical, cylindrical precipitator geometry was chosen. The electrostatic precipitator design presented here removes simulated Martian dust particles in the required range in a simulated Martian atmospheric environment. The current-voltage (I-V) characteristic curves taken for the nine precipitator configurations at 9 mbars of pressure showed that a cylindrical collecting electrode 7.0 cm in diameter with a concentric positive high voltage electrode 100 m thick provides the best range of voltage and charging corona current. This precipitator design is effective for the size of the dust particles expected in the Martian atmosphere. Mass determination, as well as microscopic images and particle size distributions of dust collected on a silicon wafer placed directly below the precipitator with the field on and off, showed excellent initial results.

METHOD FOR RECOVERING PLUTONIUM VALUES FROM SOLUTION USING A BISMUTH HYDROXIDE CARRIER PRECIPITATE

DOEpatents

Faris, B.F.

1961-04-25

Carrier precipitation processes for separating plutonium values from aqueous solutions are described. In accordance with the invention a bismuth hydroxide precipitate is formed in the plutonium-containing solution, thereby carrying plutonium values from the solution.

CONCENTRATION OF Pu USING AN IODATE PRECIPITATE

DOEpatents

Fries, B.A.

1960-02-23

A method is given for separating plutonium from lanthanum in a lanthanum fluoride carrier precipitation process for the recovery of plutonium values from an aqueous solution. The carrier precipitation process includes the steps of forming a lanthanum fluoride precipi- . tate, thereby carrying plutonium out of solution, metathesizing the fluoride precipitate to a hydroxide precipitate, and then dissolving the hydroxide precipitate in nitric acid. In accordance with the invention, the nitric acid solution, which contains plutonium and lanthanum, is made 0.05 to 0.15 molar in potassium iodate. thereby precipitating plutonium as plutonous iodate and the plutonous iodate is separated from the lanthanum- containing supernatant solution.

Students' mental models on the solubility and solubility product concept

NASA Astrophysics Data System (ADS)

Rahmi, Chusnur; Katmiati, Siti; Wiji, Mulyani, Sri

2017-05-01

This study aims to obtain some information regarding profile of students' mental models on the solubility and solubility product concept. A descriptive qualitative method was the method employed in the study. The participants of the study were students XI grade of a senior high school in Bandung. To collect the data, diagnostic test on mental model-prediction, observation, explanation (TDM-POE) instrument was employed in the study. The results of the study revealed that on the concept of precipitation formation of a reaction, 30% of students were not able to explain the precipitation formation of a reaction either in submicroscopic or symbolic level although the microscopic have been shown; 26% of students were able to explain the precipitation formation of a reaction based on the relation of Qsp and Ksp, but they were not able to explain the interaction of particles that involved in the reaction and to calculate Qsp; 26% of students were able to explain the precipitation formation of a reaction based on the relation of Qsp and Ksp, and determine the particles involved, but they did not have the knowledge about the interactions occured and were uncapable of calculating Qsp; and 18% of students were able to explain the precipitation formation of a reaction based on the relation of Qsp and Ksp, and determine the interactions of the particles involved in the reactions but they were not able to calculate Qsp. On the effect of adding common ions and decreasing pH towards the solubility concept, 96% of students were not able to explain the effect of adding common ions and decreasing pH towards the solubility either in submicroscopic or symbolic level although the microscopic have been shown; while 4% of students were only able to explain the effect of adding common ions towards the solubility based on the chemical equilibrium shifts and predict the effect of decreasing pH towards the solubility. However, they were not able to calculate the solubility before and after adding common ions and explain it up to the submicroscopic level either based on the shift of equilibrium solubility or the comparison of solubility calculation results before and after decreasing pH. Overall, the present study showed that most students obtain incomplete mental model on the solubility and solubility product concept. From the findings, it is recommended for the teachers to improve students' learning activity.

Trace Metals in Groundwater and Vadose Zone Calcite: In Situ Containment and Stabilization of Stronthium-90 and Other Divalent Metals and Radionuclides at Arid Western DOE Sites: Final Report for Award Number DE-FG07-02ER63486 to the University of Idaho (RW Smith) Environmental Management Science Program Project Number 87016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Robert W.; Fujita, Yoshiko

2007-11-07

Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) energy research and weapons complex. In situ containment and stabilization of these contaminants represents a cost-effective treatment strategy that minimizes workers’ exposure to hazardous substances, does not require removal or transport of contaminants, and generally does not generate a secondary waste stream. We have investigated an in situ bioremediation approach that immobilizes radionuclides or contaminant metals (e.g., strontium-90) by their microbially facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Calcite, a common mineral in many aquifers and vadosemore » zones in the arid west, can incorporate divalent metals such as strontium, cadmium, lead, and cobalt into its crystal structure by the formation of a solid solution. Collaborative research undertaken by the Idaho National Laboratory (INL), University of Idaho, and University of Toronto as part of this Environmental Management Science Program project has focused on in situ microbially-catalyzed urea hydrolysis, which results in an increase in pH, carbonate alkalinity, ammonium, calcite precipitation, and co-precipitation of divalent cations. In calcite-saturated aquifers, microbially facilitated co-precipitation with calcium carbonate represents a potential long-term contaminant sequestration mechanism. Key results of the project include: **Demonstrating the linkage between urea hydrolysis and calcite precipitation in field and laboratory experiments **Observing strontium incorporation into calcite precipitate by urea hydrolyzers with higher distribution coefficient than in abiotic **Developing and applying molecular methods for characterizing microbial urease activity in groundwater including a quantitative PCR method for enumerating ureolytic bacteria **Applying the suite of developed molecular methods to assess the feasibility of the proposed bioremediation technique at a contaminated site located within the 100-N area of the Hanford, Washington site **Assessing the role of nitrification on the persistence of precipitated calcite by modifying primers for identification of the amoA gene region of various ammonia oxidizing bacteria (AOB) for characterizing AOB in the field« less

¡Si, Se Puede! Achieving Academic Excellence Online

ERIC Educational Resources Information Center

Lumbreras, Ricardo, Jr.; Rupley, William H.

2017-01-01

Twenty-first century learners in post-secondary educational environments find themselves involved in online learning. Acquiring graduate degrees, especially for working professionals, has precipitated the need for effective, rigorous, relevant, and timely coursework online. Utilizing the qualitative research method of auto-ethnographic reporting,…

Evaluation of TRMM multi-satellite precipitation analysis (TMPA) against terrestrial measurement over a humid sub-tropical basin, India

NASA Astrophysics Data System (ADS)

Kumar, Dheeraj; Gautam, Amar Kant; Palmate, Santosh S.; Pandey, Ashish; Suryavanshi, Shakti; Rathore, Neha; Sharma, Nayan

2017-08-01

To support the GPM mission which is homologous to its predecessor, the Tropical Rainfall Measuring Mission (TRMM), this study has been undertaken to evaluate the accuracy of Tropical Rainfall Measuring Mission multi-satellite precipitation analysis (TMPA) daily-accumulated precipitation products for 5 years (2008-2012) using the statistical methods and contingency table method. The analysis was performed on daily, monthly, seasonal and yearly basis. The TMPA precipitation estimates were also evaluated for each grid point i.e. 0.25° × 0.25° and for 18 rain gauge stations of the Betwa River basin, India. Results indicated that TMPA precipitation overestimates the daily and monthly precipitation in general, particularly for the middle sub-basin in the non-monsoon season. Furthermore, precision of TMPA precipitation estimates declines with the decrease of altitude at both grid and sub-basin scale. The study also revealed that TMPA precipitation estimates provide better accuracy in the upstream of the basin compared to downstream basin. Nevertheless, the detection capability of daily TMPA precipitation improves with increase in altitude for drizzle rain events. However, the detection capability decreases during non-monsoon and monsoon seasons when capturing moderate and heavy rain events, respectively. The veracity of TMPA precipitation estimates was improved during the rainy season than during the dry season at all scenarios investigated. The analyses suggest that there is a need for better precipitation estimation algorithm and extensive accuracy verification against terrestrial precipitation measurement to capture the different types of rain events more reliably over the sub-humid tropical regions of India.

A time series approach to inferring groundwater recharge using the water table fluctuation method

NASA Astrophysics Data System (ADS)

Crosbie, Russell S.; Binning, Philip; Kalma, Jetse D.

2005-01-01

The water table fluctuation method for determining recharge from precipitation and water table measurements was originally developed on an event basis. Here a new multievent time series approach is presented for inferring groundwater recharge from long-term water table and precipitation records. Additional new features are the incorporation of a variable specific yield based upon the soil moisture retention curve, proper accounting for the Lisse effect on the water table, and the incorporation of aquifer drainage so that recharge can be detected even if the water table does not rise. A methodology for filtering noise and non-rainfall-related water table fluctuations is also presented. The model has been applied to 2 years of field data collected in the Tomago sand beds near Newcastle, Australia. It is shown that gross recharge estimates are very sensitive to time step size and specific yield. Properly accounting for the Lisse effect is also important to determining recharge.

Syzygies, Pluricanonical Maps, and the Birational Geometry of Varieties of Maximal Albanese Dimension

NASA Astrophysics Data System (ADS)

Tesfagiorgis, Kibrewossen B.

Satellite Precipitation Estimates (SPEs) may be the only available source of information for operational hydrologic and flash flood prediction due to spatial limitations of radar and gauge products in mountainous regions. The present work develops an approach to seamlessly blend satellite, available radar, climatological and gauge precipitation products to fill gaps in ground-based radar precipitation field. To mix different precipitation products, the error of any of the products relative to each other should be removed. For bias correction, the study uses a new ensemble-based method which aims to estimate spatially varying multiplicative biases in SPEs using a radar-gauge precipitation product. Bias factors were calculated for a randomly selected sample of rainy pixels in the study area. Spatial fields of estimated bias were generated taking into account spatial variation and random errors in the sampled values. In addition to biases, sometimes there is also spatial error between the radar and satellite precipitation estimates; one of them has to be geometrically corrected with reference to the other. A set of corresponding raining points between SPE and radar products are selected to apply linear registration using a regularized least square technique to minimize the dislocation error in SPEs with respect to available radar products. A weighted Successive Correction Method (SCM) is used to make the merging between error corrected satellite and radar precipitation estimates. In addition to SCM, we use a combination of SCM and Bayesian spatial method for merging the rain gauges and climatological precipitation sources with radar and SPEs. We demonstrated the method using two satellite-based, CPC Morphing (CMORPH) and Hydro-Estimator (HE), two radar-gauge based, Stage-II and ST-IV, a climatological product PRISM and rain gauge dataset for several rain events from 2006 to 2008 over different geographical locations of the United States. Results show that: (a) the method of ensembles helped reduce biases in SPEs significantly; (b) the SCM method in combination with the Bayesian spatial model produced a precipitation product in good agreement with independent measurements .The study implies that using the available radar pixels surrounding the gap area, rain gauge, PRISM and satellite products, a radar like product is achievable over radar gap areas that benefits the operational meteorology and hydrology community.

Atmospheric Moisture Budget and Spatial Resolution Dependence of Precipitation Extremes in Aquaplanet Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qing; Leung, Lai-Yung R.; Rauscher, Sara

This study investigates the resolution dependency of precipitation extremes in an aqua-planet framework. Strong resolution dependency of precipitation extremes is seen over both tropics and extra-tropics, and the magnitude of this dependency also varies with dynamical cores. Moisture budget analyses based on aqua-planet simulations with the Community Atmosphere Model (CAM) using the Model for Prediction Across Scales (MPAS) and High Order Method Modeling Environment (HOMME) dynamical cores but the same physics parameterizations suggest that during precipitation extremes moisture supply for surface precipitation is mainly derived from advective moisture convergence. The resolution dependency of precipitation extremes mainly originates from advective moisturemore » transport in the vertical direction. At most vertical levels over the tropics and in the lower atmosphere over the subtropics, the vertical eddy transport of mean moisture field dominates the contribution to precipitation extremes and its resolution dependency. Over the subtropics, the source of moisture, its associated energy, and the resolution dependency during extremes are dominated by eddy transport of eddies moisture at the mid- and upper-troposphere. With both MPAS and HOMME dynamical cores, the resolution dependency of the vertical advective moisture convergence is mainly explained by dynamical changes (related to vertical velocity or omega), although the vertical gradients of moisture act like averaging kernels to determine the sensitivity of the overall resolution dependency to the changes in omega at different vertical levels. The natural reduction of variability with coarser resolution, represented by areal data averaging (aggregation) effect, largely explains the resolution dependency in omega. The thermodynamic changes, which likely result from non-linear feedback in response to the large dynamical changes, are small compared to the overall changes in dynamics (omega). However, after excluding the data aggregation effect in omega, thermodynamic changes become relatively significant in offsetting the effect of dynamics leading to reduce differences between the simulated and aggregated results. Compared to MPAS, the simulated stronger vertical motion with HOMME also results in larger resolution dependency. Compared to the simulation at fine resolution, the vertical motion during extremes is insufficiently resolved/parameterized at the coarser resolution even after accounting for the natural reduction in variability with coarser resolution, and this is more distinct in the simulation with HOMME. To reduce uncertainties in simulated precipitation extremes, future development in cloud parameterizations must address their sensitivity to spatial resolution as well as dynamical cores.« less

Implementation of Biofilm Permeability Models for Mineral Reactions in Saturated Porous Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freedman, Vicky L.; Saripalli, Kanaka P.; Bacon, Diana H.

2005-02-22

An approach based on continuous biofilm models is proposed for modeling permeability changes due to mineral precipitation and dissolution in saturated porous media. In contrast to the biofilm approach, implementation of the film depositional models within a reactive transport code requires a time-dependent calculation of the mineral films in the pore space. Two different methods for this calculation are investigated. The first method assumes a direct relationship between changes in mineral radii (i.e., surface area) and changes in the pore space. In the second method, an effective change in pore radii is calculated based on the relationship between permeability andmore » grain size. Porous media permeability is determined by coupling the film permeability models (Mualem and Childs and Collis-George) to a volumetric model that incorporates both mineral density and reactive surface area. Results from single mineral dissolution and single mineral precipitation simulations provide reasonable estimates of permeability, though they under predict the magnitude of permeability changes relative to the Kozeny and Carmen model. However, a comparison of experimental and simulated data show that the Mualem film model is the only one that can replicate the oscillations in permeability that occur as a result of simultaneous dissolution and precipitation reactions occurring within the porous media.« less

Preparation of Fe3O4/Bentonite Nanocomposite from Natural Iron Sand by Co-precipitation Method for Adsorbents Materials

NASA Astrophysics Data System (ADS)

Sebayang, Perdamean; Kurniawan, Candra; Aryanto, Didik; Arief Setiadi, Eko; Tamba, Konni; Djuhana; Sudiro, Toto

2018-03-01

An adsorption method is one of the effective ways to filter the heavy metals wastes in aqueous system. In this paper, the Fe3O4/bentonite nanocomposites were successfully prepared from natural iron sand by co-precipitation method. The chemical process was carried out by dissolving and hot stirring the milled iron sand and bentonite in acid solution and precipitating it by NH4OH. The sediment was then washed using distilled water to neutralize pH and dried at 100 °C for 5 hours to produce Fe3O4/bentonite powders. The samples were characterized by XRD, FTIR, BET, TEM, VSM and AAS. All samples were composed by Fe3O4 single phase with a spinnel structure and lattice parameter of 8.373 Å. The transmittance peak of FTIR curve proved that the Fe3O4 particles and bentonite had a molecular bonding. The addition of bentonite to Fe3O4 nanoparticles generally reduced the magnetic properties of Fe3O4/bentonite nanocomposites. The optimum condition of 30 wt% bentonite resulted 105.9 m2/g in surface area, 14 nm in an average particle size and 3.2 nm in pore size. It can be used as Cu and Pb adsorbent materials.

Evaluation of rainfall structure on hydrograph simulation: Comparison of radar and interpolated methods, a study case in a tropical catchment

NASA Astrophysics Data System (ADS)

Velasquez, N.; Ochoa, A.; Castillo, S.; Hoyos Ortiz, C. D.

2017-12-01

The skill of river discharge simulation using hydrological models strongly depends on the quality and spatio-temporal representativeness of precipitation during storm events. All precipitation measurement strategies have their own strengths and weaknesses that translate into discharge simulation uncertainties. Distributed hydrological models are based on evolving rainfall fields in the same time scale as the hydrological simulation. In general, rainfall measurements from a dense and well maintained rain gauge network provide a very good estimation of the total volume for each rainfall event, however, the spatial structure relies on interpolation strategies introducing considerable uncertainty in the simulation process. On the other hand, rainfall retrievals from radar reflectivity achieve a better spatial structure representation but with higher uncertainty in the surface precipitation intensity and volume depending on the vertical rainfall characteristics and radar scan strategy. To assess the impact of both rainfall measurement methodologies on hydrological simulations, and in particular the effects of the rainfall spatio-temporal variability, a numerical modeling experiment is proposed including the use of a novel QPE (Quantitative Precipitation Estimation) method based on disdrometer data in order to estimate surface rainfall from radar reflectivity. The experiment is based on the simulation of 84 storms, the hydrological simulations are carried out using radar QPE and two different interpolation methods (IDW and TIN), and the assessment of simulated peak flow. Results show significant rainfall differences between radar QPE and the interpolated fields, evidencing a poor representation of storms in the interpolated fields, which tend to miss the precise location of the intense precipitation cores, and to artificially generate rainfall in some areas of the catchment. Regarding streamflow modelling, the potential improvement achieved by using radar QPE depends on the density of the rain gauge network and its distribution relative to the precipitation events. The results for the 84 storms show a better model skill using radar QPE than the interpolated fields. Results using interpolated fields are highly affected by the dominant rainfall type and the basin scale.

Reconstructing missing information on precipitation datasets: impact of tails on adopted statistical distributions.

NASA Astrophysics Data System (ADS)

Pedretti, Daniele; Beckie, Roger Daniel

2014-05-01

Missing data in hydrological time-series databases are ubiquitous in practical applications, yet it is of fundamental importance to make educated decisions in problems involving exhaustive time-series knowledge. This includes precipitation datasets, since recording or human failures can produce gaps in these time series. For some applications, directly involving the ratio between precipitation and some other quantity, lack of complete information can result in poor understanding of basic physical and chemical dynamics involving precipitated water. For instance, the ratio between precipitation (recharge) and outflow rates at a discharge point of an aquifer (e.g. rivers, pumping wells, lysimeters) can be used to obtain aquifer parameters and thus to constrain model-based predictions. We tested a suite of methodologies to reconstruct missing information in rainfall datasets. The goal was to obtain a suitable and versatile method to reduce the errors given by the lack of data in specific time windows. Our analyses included both a classical chronologically-pairing approach between rainfall stations and a probability-based approached, which accounted for the probability of exceedence of rain depths measured at two or multiple stations. Our analyses proved that it is not clear a priori which method delivers the best methodology. Rather, this selection should be based considering the specific statistical properties of the rainfall dataset. In this presentation, our emphasis is to discuss the effects of a few typical parametric distributions used to model the behavior of rainfall. Specifically, we analyzed the role of distributional "tails", which have an important control on the occurrence of extreme rainfall events. The latter strongly affect several hydrological applications, including recharge-discharge relationships. The heavy-tailed distributions we considered were parametric Log-Normal, Generalized Pareto, Generalized Extreme and Gamma distributions. The methods were first tested on synthetic examples, to have a complete control of the impact of several variables such as minimum amount of data required to obtain reliable statistical distributions from the selected parametric functions. Then, we applied the methodology to precipitation datasets collected in the Vancouver area and on a mining site in Peru.

Improving PERSIANN-CCS rain estimation using probabilistic approach and multi-sensors information

NASA Astrophysics Data System (ADS)

Karbalaee, N.; Hsu, K. L.; Sorooshian, S.; Kirstetter, P.; Hong, Y.

2016-12-01

This presentation discusses the recent implemented approaches to improve the rainfall estimation from Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network-Cloud Classification System (PERSIANN-CCS). PERSIANN-CCS is an infrared (IR) based algorithm being integrated in the IMERG (Integrated Multi-Satellite Retrievals for the Global Precipitation Mission GPM) to create a precipitation product in 0.1x0.1degree resolution over the chosen domain 50N to 50S every 30 minutes. Although PERSIANN-CCS has a high spatial and temporal resolution, it overestimates or underestimates due to some limitations.PERSIANN-CCS can estimate rainfall based on the extracted information from IR channels at three different temperature threshold levels (220, 235, and 253k). This algorithm relies only on infrared data to estimate rainfall indirectly from this channel which cause missing the rainfall from warm clouds and false estimation for no precipitating cold clouds. In this research the effectiveness of using other channels of GOES satellites such as visible and water vapors has been investigated. By using multi-sensors the precipitation can be estimated based on the extracted information from multiple channels. Also, instead of using the exponential function for estimating rainfall from cloud top temperature, the probabilistic method has been used. Using probability distributions of precipitation rates instead of deterministic values has improved the rainfall estimation for different type of clouds.

Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects

PubMed Central

Devaraju, N.; Bala, Govindasamy; Modak, Angshuman

2015-01-01

In this paper, using idealized climate model simulations, we investigate the biogeophysical effects of large-scale deforestation on monsoon regions. We find that the remote forcing from large-scale deforestation in the northern middle and high latitudes shifts the Intertropical Convergence Zone southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America, and Australia). The magnitude of the monsoonal precipitation changes depends on the location of deforestation, with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most, with 18% decline in precipitation over India. Our results indicate that any comprehensive assessment of afforestation/reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation alongside the large local impacts on temperatures. PMID:25733889

Application of precipitation methods for the production of water-insoluble drug nanocrystals: production techniques and stability of nanocrystals.

PubMed

Xia, Dengning; Gan, Yong; Cui, Fude

2014-01-01

This review focuses on using precipitation (bottom-up) method to produce water-insoluble drug nanocrystals, and the stability issues of nanocrystals. The precipitation techniques for production of ultra-fine particles have been widely researched for last few decades. In these techniques, precipitation of solute is achieved by addition of a non-solvent for solute called anti-solvent to decrease the solvent power for the solute dissolved in a solution. The anti-solvent can be water, organic solvents or supercritical fluids. In this paper, efforts have been made to review the precipitation techniques involving the anti-solvent precipitation by simple mixing, impinging jet mixing, multi-inlet vortex mixing, the using of high-gravity, ultrasonic waves and supercritical fluids. The key to the success of yielding stable nanocrystals in these techniques is to control the nucleation kinetics and particle growth through mixing during precipitation based on crystallization theories. The stability issues of the nanocrystals, such as sedimentation, Ostwald ripening, agglomeration and cementing of crystals, change of crystalline state, and the approaches to stabilizing nanocrystals are also discussed in detail.

The effects of monsoons and climate teleconnections on the Niangziguan Karst Spring discharge in North China

NASA Astrophysics Data System (ADS)

Zhang, Juan; Hao, Yonghong; Hu, Bill X.; Huo, Xueli; Hao, Pengmei; Liu, Zhongfang

2017-01-01

Karst aquifers supply drinking water for 25 % of the world's population, and they are, however, vulnerable to climate change. This study is aimed to investigate the effects of various monsoons and teleconnection patterns on Niangziguan Karst Spring (NKS) discharge in North China for sustainable exploration of the karst groundwater resources. The monsoons studied include the Indian Summer Monsoon, the West North Pacific Monsoon and the East Asian Summer Monsoon. The climate teleconnection patterns explored include the Indian Ocean Dipole, E1 Niño Southern Oscillation, and the Pacific Decadal Oscillation. The wavelet transform and wavelet coherence methods are used to analyze the karst hydrological processes in the NKS Basin, and reveal the relations between the climate indices with precipitation and the spring discharge. The study results indicate that both the monsoons and the climate teleconnections significantly affect precipitation in the NKS Basin. The time scales that the monsoons resonate with precipitation are strongly concentrated on the time scales of 0.5-, 1-, 2.5- and 3.5-year, and that climate teleconnections resonate with precipitation are relatively weak and diverged from 0.5-, 1-, 2-, 2.5-, to 8-year time scales, respectively. Because the climate signals have to overcome the resistance of heterogeneous aquifers before reaching spring discharge, with high energy, the strong climate signals (e.g. monsoons) are able to penetrate through aquifers and act on spring discharge. So the spring discharge is more strongly affected by monsoons than the climate teleconnections. During the groundwater flow process, the precipitation signals will be attenuated, delayed, merged, and changed by karst aquifers. Therefore, the coherence coefficients between the spring discharge and climate indices are smaller than those between precipitation and climate indices. Further, the fluctuation of the spring discharge is not coincident with that of precipitation in most situations. Karst spring discharge as a proxy can represent groundwater resource variability at a regional scale, and is more strongly influenced by climate variation.

Application of advanced data assimilation techniques to the study of cloud and precipitation feedbacks in the tropical climate system

NASA Astrophysics Data System (ADS)

Posselt, Derek J.

The research documented in this study centers around two topics: evaluation of the response of precipitating cloud systems to changes in the tropical climate system, and assimilation of cloud and precipitation information from remote-sensing platforms. The motivation for this work proceeds from the following outstanding problems: (1) Use of models to study the response of clouds to perturbations in the climate system is hampered by uncertainties in cloud microphysical parameterizations. (2) Though there is an ever-growing set of available observations, cloud and precipitation assimilation remains a difficult problem, particularly in the tropics. (3) Though it is widely acknowledged that cloud and precipitation processes play a key role in regulating the Earth's response to surface warming, the response of the tropical hydrologic cycle to climate perturbations remains largely unknown. The above issues are addressed in the following manner. First, Markov chain Monte Carlo (MCMC) methods are used to quantify the sensitivity of the NASA Goddard Cumulus Ensemble (GCE) cloud resolving model (CRM) to changes in its cloud odcrnpbymiC8l parameters. TRMM retrievals of precipitation rate, cloud properties, and radiative fluxes and heating rates over the South China Sea are then assimilated into the GCE model to constrain cloud microphysical parameters to values characteristic of convection in the tropics, and the resulting observation-constrained model is used to assess the response of the tropical hydrologic cycle to surface warming. The major findings of this study are the following: (1) MCMC provides an effective tool with which to evaluate both model parameterizations and the assumption of Gaussian statistics used in optimal estimation procedures. (2) Statistics of the tropical radiation budget and hydrologic cycle can be used to effectively constrain CRM cloud microphysical parameters. (3) For 2D CRM simulations run with and without shear, the precipitation efficiency of cloud systems increases with increasing sea surface temperature, while the high cloud fraction and outgoing shortwave radiation decrease.

Precipitating Condensation Clouds in Substellar Atmospheres

NASA Technical Reports Server (NTRS)

Ackerman, Andrew S.; Marley, Mark S.; Gore, Warren J. (Technical Monitor)

2000-01-01

We present a method to calculate vertical profiles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent diffusion and precipitation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with previous methods. An adjustable parameter describing the efficiency of precipitation allows the new model to span the range of predictions from previous models. Calculations for the Jovian ammonia cloud are found to be consistent with observational constraints. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet.

PLUTONIUM CARRIER METATHESIS WITH ORGANIC REAGENT

DOEpatents

Thompson, S.G.

1958-07-01

A method is described for converting a plutonium containing bismuth phosphate carrier precipitate Into a compositton more readily soluble in acid. The method consists of dissolving the bismuth phosphate precipitate in an aqueous solution of alkali metal hydroxide, and adding one of a certaia group of organic compounds, e.g., polyhydric alcohols or a-hydrorycarboxylic acids. The mixture is then heated causiing formation of a bismuth hydroxide precipitate containing plutonium which may be readily dissolved in nitric acid for further processing.

Exploring precipitation pattern scaling methodologies and robustness among CMIP5 models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kravitz, Ben; Lynch, Cary; Hartin, Corinne

Pattern scaling is a well-established method for approximating modeled spatial distributions of changes in temperature by assuming a time-invariant pattern that scales with changes in global mean temperature. We compare two methods of pattern scaling for annual mean precipitation (regression and epoch difference) and evaluate which method is better in particular circumstances by quantifying their robustness to interpolation/extrapolation in time, inter-model variations, and inter-scenario variations. Both the regression and epoch-difference methods (the two most commonly used methods of pattern scaling) have good absolute performance in reconstructing the climate model output, measured as an area-weighted root mean square error. We decomposemore » the precipitation response in the RCP8.5 scenario into a CO 2 portion and a non-CO 2 portion. Extrapolating RCP8.5 patterns to reconstruct precipitation change in the RCP2.6 scenario results in large errors due to violations of pattern scaling assumptions when this CO 2-/non-CO 2-forcing decomposition is applied. As a result, the methodologies discussed in this paper can help provide precipitation fields to be utilized in other models (including integrated assessment models or impacts assessment models) for a wide variety of scenarios of future climate change.« less

Exploring precipitation pattern scaling methodologies and robustness among CMIP5 models

DOE PAGES

Kravitz, Ben; Lynch, Cary; Hartin, Corinne; ...

2017-05-12

Pattern scaling is a well-established method for approximating modeled spatial distributions of changes in temperature by assuming a time-invariant pattern that scales with changes in global mean temperature. We compare two methods of pattern scaling for annual mean precipitation (regression and epoch difference) and evaluate which method is better in particular circumstances by quantifying their robustness to interpolation/extrapolation in time, inter-model variations, and inter-scenario variations. Both the regression and epoch-difference methods (the two most commonly used methods of pattern scaling) have good absolute performance in reconstructing the climate model output, measured as an area-weighted root mean square error. We decomposemore » the precipitation response in the RCP8.5 scenario into a CO 2 portion and a non-CO 2 portion. Extrapolating RCP8.5 patterns to reconstruct precipitation change in the RCP2.6 scenario results in large errors due to violations of pattern scaling assumptions when this CO 2-/non-CO 2-forcing decomposition is applied. As a result, the methodologies discussed in this paper can help provide precipitation fields to be utilized in other models (including integrated assessment models or impacts assessment models) for a wide variety of scenarios of future climate change.« less

Testing and development of transfer functions for weighing precipitation gauges in WMO-SPICE

NASA Astrophysics Data System (ADS)

Kochendorfer, John; Nitu, Rodica; Wolff, Mareile; Mekis, Eva; Rasmussen, Roy; Baker, Bruce; Earle, Michael E.; Reverdin, Audrey; Wong, Kai; Smith, Craig D.; Yang, Daqing; Roulet, Yves-Alain; Meyers, Tilden; Buisan, Samuel; Isaksen, Ketil; Brækkan, Ragnar; Landolt, Scott; Jachcik, Al

2018-02-01

Weighing precipitation gauges are used widely for the measurement of all forms of precipitation, and are typically more accurate than tipping-bucket precipitation gauges. This is especially true for the measurement of solid precipitation; however, weighing precipitation gauge measurements must still be adjusted for undercatch in snowy, windy conditions. In WMO-SPICE (World Meteorological Organization Solid Precipitation InterComparison Experiment), different types of weighing precipitation gauges and shields were compared, and adjustments were determined for the undercatch of solid precipitation caused by wind. For the various combinations of gauges and shields, adjustments using both new and previously existing transfer functions were evaluated. For most of the gauge and shield combinations, previously derived transfer functions were found to perform as well as those more recently derived. This indicates that wind shield type (or lack thereof) is more important in determining the magnitude of wind-induced undercatch than the type of weighing precipitation gauge. It also demonstrates the potential for widespread use of the previously developed transfer functions. Another overarching result was that, in general, the more effective shields, which were associated with smaller unadjusted errors, also produced more accurate measurements after adjustment. This indicates that although transfer functions can effectively reduce measurement biases, effective wind shielding is still required for the most accurate measurement of solid precipitation.

Quantifying the synergistic effect of the precipitation and land use on sandy desertification at county level: a case study in Naiman Banner, Northern China.

PubMed

Xiaodong, Ge; Jinren, Ni; Zhenshan, Li; Ronggui, Hu; Xin, Ming; Qing, Ye

2013-07-15

Assessing the driving forces of sandy desertification is fundamental and important for its control. It has been widely accepted that both climatic conditions and land use have great impact on sandy desertification in northern China. However, the relative role and synergistic effect of each driving force of sandy desertification are still not clear. In this paper, an indicator named as SI was defined to represent the integrated probability of sandy desertification caused by land use. A quantitative method was developed for characterizing the relative roles of annual precipitation and land use to sandy desertification in both spatial and temporal dimensions at county level. Results showed that, at county level, land use was the main cause of sandy desertification for Naiman Banner since 1987-2009. In the case of spatial dimension, the different combination of land use types decided the distribution of sandy desertification probability and finally decided the spatial pattern of bared sand land. In the case of temporal dimension, the synergistic effect of land use and precipitation highly influenced the spatial distribution of sandy desertification. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sequestration of Sr-90 Subsurface Contamination in the Hanford 100-N Area by Surface Infiltration of a Ca-Citrate-Phosphate Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szecsody, James E.; Rockhold, Mark L.; Oostrom, Martinus

The objective of this project is to develop a method to emplace apatite precipitate in the 100N vadose zone, which results in sorption and ultimately incorporation of Sr-90 into the apatite structure. The Ca-citrate-PO4 solution can be infiltrated into unsaturated sediments to result in apatite precipitate to provide effective treatment of Sr-90 contamination. Microbial redistribution during solution infiltration and a high rate of citrate biodegradation for river water microbes (water used for solution infiltration) results in a relatively even spatial distribution of the citrate biodegradation rate and ultimately apatite precipitate in the sediment. Manipulation of the Ca-citrate-PO4 solution infiltration strategymore » can be used to result in apatite precipitate in the lower half of the vadose zone (where most of the Sr-90 is located) and within low-K layers (which are hypothesized to have higher Sr-90 concentrations). The most effective infiltration strategy to precipitate apatite at depth (and with sufficient lateral spread) was to infiltrate a high concentration solution (6 mM Ca, 15 mM citrate, 60 mM PO4) at a rapid rate (near ponded conditions), followed by rapid, then slow water infiltration. Repeated infiltration events, with sufficient time between events to allow water drainage in the sediment profile can be used to buildup the mass of apatite precipitate at greater depth. Low-K heterogeneities were effectively treated, as the higher residual water content maintained in these zones resulted in higher apatite precipitate concentration. High-K zones did not receive sufficient treatment by infiltration, although an alternative strategy of air/surfactant (foam) was demonstrated effective for targeting high-K zones. The flow rate manipulation used in this study to treat specific depths and heterogeneities are not as easy to implement at field scale due to the lack of characterization of heterogeneities and difficulty tracking the wetting front over a large subsurface area. However, the use of real-time surface and cross-borehole geophysics can be used to track the infiltrating Ca-citrate-PO4 front so some adjustments can be made in the infiltration rate to precipitate apatite in desired zones. In addition, the reactive transport code used in this study with field scale physical parameters for sediments can be used to evaluate infiltration strategies along with preliminary water infiltration tests at field scale.« less

Accuracy evaluation of ClimGen weather generator and daily to hourly disaggregation methods in tropical conditions

NASA Astrophysics Data System (ADS)

Safeeq, Mohammad; Fares, Ali

2011-12-01

Daily and sub-daily weather data are often required for hydrological and environmental modeling. Various weather generator programs have been used to generate synthetic climate data where observed climate data are limited. In this study, a weather data generator, ClimGen, was evaluated for generating information on daily precipitation, temperature, and wind speed at four tropical watersheds located in Hawai`i, USA. We also evaluated different daily to sub-daily weather data disaggregation methods for precipitation, air temperature, dew point temperature, and wind speed at Mākaha watershed. The hydrologic significance values of the different disaggregation methods were evaluated using Distributed Hydrology Soil Vegetation Model. MuDRain and diurnal method performed well over uniform distribution in disaggregating daily precipitation. However, the diurnal method is more consistent if accurate estimates of hourly precipitation intensities are desired. All of the air temperature disaggregation methods performed reasonably well, but goodness-of-fit statistics were slightly better for sine curve model with 2 h lag. Cosine model performed better than random model in disaggregating daily wind speed. The largest differences in annual water balance were related to wind speed followed by precipitation and dew point temperature. Simulated hourly streamflow, evapotranspiration, and groundwater recharge were less sensitive to the method of disaggregating daily air temperature. ClimGen performed well in generating the minimum and maximum temperature and wind speed. However, for precipitation, it clearly underestimated the number of extreme rainfall events with an intensity of >100 mm/day in all four locations. ClimGen was unable to replicate the distribution of observed precipitation at three locations (Honolulu, Kahului, and Hilo). ClimGen was able to reproduce the distributions of observed minimum temperature at Kahului and wind speed at Kahului and Hilo. Although the weather data generation and disaggregation methods were concentrated in a few Hawaiian watersheds, the results presented can be used to similar mountainous location settings, as well as any specific locations aimed at furthering the site-specific performance evaluation of these tested models.

Scaling Linguistic Characterization of Precipitation Variability

NASA Astrophysics Data System (ADS)

Primo, C.; Gutierrez, J. M.

2003-04-01

Rainfall variability is influenced by changes in the aggregation of daily rainfall. This problem is of great importance for hydrological, agricultural and ecological applications. Rainfall averages, or accumulations, are widely used as standard climatic parameters. However different aggregation schemes may lead to the same average or accumulated values. In this paper we present a fractal method to characterize different aggregation schemes. The method provides scaling exponents characterizing weekly or monthly rainfall patterns for a given station. To this aim, we establish an analogy with linguistic analysis, considering precipitation as a discrete variable (e.g., rain, no rain). Each weekly, or monthly, symbolic precipitation sequence of observed precipitation is then considered as a "word" (in this case, a binary word) which defines a specific weekly rainfall pattern. Thus, each site defines a "language" characterized by the words observed in that site during a period representative of the climatology. Then, the more variable the observed weekly precipitation sequences, the more complex the obtained language. To characterize these languages, we first applied the Zipf's method obtaining scaling histograms of rank ordered frequencies. However, to obtain significant exponents, the scaling must be maintained some orders of magnitude, requiring long sequences of daily precipitation which are not available at particular stations. Thus this analysis is not suitable for applications involving particular stations (such as regionalization). Then, we introduce an alternative fractal method applicable to data from local stations. The so-called Chaos-Game method uses Iterated Function Systems (IFS) for graphically representing rainfall languages, in a way that complex languages define complex graphical patterns. The box-counting dimension and the entropy of the resulting patterns are used as linguistic parameters to quantitatively characterize the complexity of the patterns. We illustrate the high climatological discrimination power of the linguistic parameters in the Iberian peninsula, when compared with other standard techniques (such as seasonal mean accumulated precipitation). As an example, standard and linguistic parameters are used as inputs for a clustering regionalization method, comparing the resulting clusters.

Multiphysics phase field modeling of hydrogen diffusion and delta-hydride precipitation in alpha-zirconium

NASA Astrophysics Data System (ADS)

Jokisaari, Andrea M.

Hydride precipitation in zirconium is a significant factor limiting the lifetime of nuclear fuel cladding, because hydride microstructures play a key role in the degradation of fuel cladding. However, the behavior of hydrogen in zirconium has typically been modeled using mean field approaches, which do not consider microstructural evolution. This thesis describes a quantitative microstructural evolution model for the alpha-zirconium/delta-hydride system and the associated numerical methods and algorithms that were developed. The multiphysics, phase field-based model incorporates CALPHAD free energy descriptions, linear elastic solid mechanics, and classical nucleation theory. A flexible simulation software implementing the model, Hyrax, is built on the Multiphysics Object Oriented Simulation Environment (MOOSE) finite element framework. Hyrax is open-source and freely available; moreover, the numerical methods and algorithms that have been developed are generalizable to other systems. The algorithms are described in detail, and verification studies for each are discussed. In addition, analyses of the sensitivity of the simulation results to the choice of numerical parameters are presented. For example, threshold values for the CALPHAD free energy algorithm and the use of mesh and time adaptivity when employing the nucleation algorithm are studied. Furthermore, preliminary insights into the nucleation behavior of delta-hydrides are described. These include a) the sensitivities of the nucleation rate to temperature, interfacial energy, composition and elastic energy, b) the spatial variation of the nucleation rate around a single precipitate, and c) the effect of interfacial energy and nucleation rate on the precipitate microstructure. Finally, several avenues for future work are discussed. Topics encompass the terminal solid solubility hysteresis of hydrogen in zirconium and the effects of the alpha/delta interfacial energy, as well as thermodiffusion, plasticity, and irradiation, which are not yet accounted for in the model.

Increasing influence of heat stress on French maize yields from the 1960s to the 2030s

PubMed Central

Hawkins, Ed; Fricker, Thomas E; Challinor, Andrew J; Ferro, Christopher A T; Kit Ho, Chun; Osborne, Tom M

2013-01-01

Improved crop yield forecasts could enable more effective adaptation to climate variability and change. Here, we explore how to combine historical observations of crop yields and weather with climate model simulations to produce crop yield projections for decision relevant timescales. Firstly, the effects on historical crop yields of improved technology, precipitation and daily maximum temperatures are modelled empirically, accounting for a nonlinear technology trend and interactions between temperature and precipitation, and applied specifically for a case study of maize in France. The relative importance of precipitation variability for maize yields in France has decreased significantly since the 1960s, likely due to increased irrigation. In addition, heat stress is found to be as important for yield as precipitation since around 2000. A significant reduction in maize yield is found for each day with a maximum temperature above 32 °C, in broad agreement with previous estimates. The recent increase in such hot days has likely contributed to the observed yield stagnation. Furthermore, a general method for producing near-term crop yield projections, based on climate model simulations, is developed and utilized. We use projections of future daily maximum temperatures to assess the likely change in yields due to variations in climate. Importantly, we calibrate the climate model projections using observed data to ensure both reliable temperature mean and daily variability characteristics, and demonstrate that these methods work using retrospective predictions. We conclude that, to offset the projected increased daily maximum temperatures over France, improved technology will need to increase base level yields by 12% to be confident about maintaining current levels of yield for the period 2016–2035; the current rate of yield technology increase is not sufficient to meet this target. PMID:23504849

Precipitation phase separation schemes in the Naqu River basin, eastern Tibetan plateau

NASA Astrophysics Data System (ADS)

Liu, Shaohua; Yan, Denghua; Qin, Tianling; Weng, Baisha; Lu, Yajing; Dong, Guoqiang; Gong, Boya

2018-01-01

Precipitation phase has a profound influence on the hydrological processes in the Naqu River basin, eastern Tibetan plateau. However, there are only six meteorological stations with precipitation phase (rainfall/snowfall/sleet) before 1979 within and around the basin. In order to separate snowfall from precipitation, a new separation scheme with S-shaped curve of snowfall proportion as an exponential function of daily mean temperature was developed. The determinations of critical temperatures in the single/two temperature threshold (STT/TTT2) methods were explored accordingly, and the temperature corresponding to the 50 % snowfall proportion (SP50 temperature) is an efficiently critical temperature for the STT, and two critical temperatures in TTT2 can be determined based on the exponential function and SP50 temperature. Then, different separation schemes were evaluated in separating snowfall from precipitation in the Naqu River basin. The results show that the S-shaped curve methods outperform other separation schemes. Although the STT and TTT2 slightly underestimate and overestimate the snowfall when the temperature is higher and colder than SP50 temperature respectively, the monthly and annual separation snowfalls are generally consistent with the observed snowfalls. On the whole, S-shaped curve methods, STT, and TTT2 perform well in separating snowfall from precipitation with the Pearson correlation coefficient of annual separation snowfall above 0.8 and provide possible approaches to separate the snowfall from precipitation for hydrological modelling.

A comparison of monthly precipitation point estimates at 6 locations in Iran using integration of soft computing methods and GARCH time series model

NASA Astrophysics Data System (ADS)

Mehdizadeh, Saeid; Behmanesh, Javad; Khalili, Keivan

2017-11-01

Precipitation plays an important role in determining the climate of a region. Precise estimation of precipitation is required to manage and plan water resources, as well as other related applications such as hydrology, climatology, meteorology and agriculture. Time series of hydrologic variables such as precipitation are composed of deterministic and stochastic parts. Despite this fact, the stochastic part of the precipitation data is not usually considered in modeling of precipitation process. As an innovation, the present study introduces three new hybrid models by integrating soft computing methods including multivariate adaptive regression splines (MARS), Bayesian networks (BN) and gene expression programming (GEP) with a time series model, namely generalized autoregressive conditional heteroscedasticity (GARCH) for modeling of the monthly precipitation. For this purpose, the deterministic (obtained by soft computing methods) and stochastic (obtained by GARCH time series model) parts are combined with each other. To carry out this research, monthly precipitation data of Babolsar, Bandar Anzali, Gorgan, Ramsar, Tehran and Urmia stations with different climates in Iran were used during the period of 1965-2014. Root mean square error (RMSE), relative root mean square error (RRMSE), mean absolute error (MAE) and determination coefficient (R2) were employed to evaluate the performance of conventional/single MARS, BN and GEP, as well as the proposed MARS-GARCH, BN-GARCH and GEP-GARCH hybrid models. It was found that the proposed novel models are more precise than single MARS, BN and GEP models. Overall, MARS-GARCH and BN-GARCH models yielded better accuracy than GEP-GARCH. The results of the present study confirmed the suitability of proposed methodology for precise modeling of precipitation.

Spatiotemporal variations of the twentieth century Tibetan Plateau precipitation based on the monthly 2.5° reconstructed data

NASA Astrophysics Data System (ADS)

Shen, Samuel S. P.; Clarke, Gregori; Shen, Bo-Wen; Yao, Tandong

2017-12-01

This paper studies the spatiotemporal variations of precipitation over the Tibetan Plateau (TP) region with latitude and longitude ranges of (25° N, 45° N) and (65° E, 105° E) of the twentieth century from January 1901-December 2000. A long-term (January 1901-December 2009) TP monthly precipitation dataset with 2.5° latitude-longitude resolution is generated in this paper using spectral optimal gridding (SOG) method. The method uses the Global Precipitation Climatology Center (GPCC) ground station data to anchor the basis of empirical orthogonal functions (EOFs) computed from the Global Precipitation Climatology Project (GPCP) data. Our gridding takes teleconnection into account and uses data from stations both within and outside of the TP region. While the annual total precipitation increased at an approximate rate of 2.6 mm per decade in the period of 1971-2000 exists, no significant increase of TP precipitation from 1901 to 2000 was found. Our rate is less than those of previous publications based only on the TP stations because our data consider the entire TP region, including desert and high-altitude areas. An analysis of extremes and spatiotemporal patterns of our data shows that our reconstructed data can properly quantify the reported disasters of flooding and droughts in India, Bangladesh, and China for the following events: flooding in 1988 and 1998 and drought in 1972. Our time-frequency analysis using the empirical mode decomposition method shows that our nonlinear trend agrees well with the linear trend in the period from 1971 to 2000. The spatiotemporal variation characteristics documented in this paper can help understand atmospheric circulations on TP precipitation and validate the TP precipitation in climate models.

Comparison Of Downscaled CMIP5 Precipitation Datasets For Projecting Changes In Extreme Precipitation In The San Francisco Bay Area.

NASA Technical Reports Server (NTRS)

Milesi, Cristina; Costa-Cabral, Mariza; Rath, John; Mills, William; Roy, Sujoy; Thrasher, Bridget; Wang, Weile; Chiang, Felicia; Loewenstein, Max; Podolske, James

2014-01-01

Water resource managers planning for the adaptation to future events of extreme precipitation now have access to high resolution downscaled daily projections derived from statistical bias correction and constructed analogs. We also show that along the Pacific Coast the Northern Oscillation Index (NOI) is a reliable predictor of storm likelihood, and therefore a predictor of seasonal precipitation totals and likelihood of extremely intense precipitation. Such time series can be used to project intensity duration curves into the future or input into stormwater models. However, few climate projection studies have explored the impact of the type of downscaling method used on the range and uncertainty of predictions for local flood protection studies. Here we present a study of the future climate flood risk at NASA Ames Research Center, located in South Bay Area, by comparing the range of predictions in extreme precipitation events calculated from three sets of time series downscaled from CMIP5 data: 1) the Bias Correction Constructed Analogs method dataset downscaled to a 1/8 degree grid (12km); 2) the Bias Correction Spatial Disaggregation method downscaled to a 1km grid; 3) a statistical model of extreme daily precipitation events and projected NOI from CMIP5 models. In addition, predicted years of extreme precipitation are used to estimate the risk of overtopping of the retention pond located on the site through simulations of the EPA SWMM hydrologic model. Preliminary results indicate that the intensity of extreme precipitation events is expected to increase and flood the NASA Ames retention pond. The results from these estimations will assist flood protection managers in planning for infrastructure adaptations.

Investigation of precipitate refinement in Mg alloys by an analytical composite failure model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tabei, Ali; Li, Dongsheng; Lavender, Curt A.

2015-10-01

An analytical model is developed to simulate precipitate refinement in second phase strengthened magnesium alloys. The model is developed based on determination of the stress fields inside elliptical precipitates embedded in a rate dependent inelastic matrix. The stress fields are utilized to determine the failure mode that governs the refinement behavior. Using an AZ31 Mg alloy as an example, the effects the applied load, aspect ratio and orientation of the particle is studied on the macroscopic failure of a single α-Mg17Al12 precipitate. Additionally, a temperature dependent version of the corresponding constitutive law is used to incorporate the effects of temperature.more » In plane strain compression, an extensional failure mode always fragments the precipitates. The critical strain rate at which the precipitates start to fail strongly depends on the orientation of the precipitate with respect to loading direction. The results show that the higher the aspect ratio is, the easier the precipitate fractures. Precipitate shape is another factor influencing the failure response. In contrast to elliptical precipitates with high aspect ratio, spherical precipitates are strongly resistant to sectioning. In pure shear loading, in addition to the extensional mode of precipitate failure, a shearing mode may get activated depending on orientation and aspect ratio of the precipitate. The effect of temperature in relation to strain rate was also verified for plane strain compression and pure shear loading cases.« less

Solids precipitation in crude oils, gas-to-liquids and their blends

NASA Astrophysics Data System (ADS)

Ramanathan, Karthik

Gas-to-liquids (GTL) liquids are obtained from syngas by the Fischer-Tropsch synthesis. The blending of GTL liquids produced from natural gas/coal reserves and crude oils is a possibility in the near future for multiple reasons. Solids precipitation is a major problem in pipelines and refineries leading to significant additional operating costs. The effect of the addition of a paraffinic GTL liquid to crude oils on solids precipitation was investigated in this study. A Fourier transform infrared (FT-IR) spectroscopic technique was used to obtain solid-liquid equilibria (SLE) data for the various samples. The SLE of multiple systems of model oils composed of n-alkanes was investigated preliminarily. Blends of a model oil simulating a GTL liquid composition and a crude oil showed that the wax precipitation temperature (WPT) decreased upon blending. Three crude oils from different geographic regions (Alaskan North Slope, Colorado and Venezuela) and a laboratory-produced GTL liquid were used in the preparation of blends with five different concentrations of the GTL liquid. The wax precipitation temperatures of the blends were found to decrease with the increasing addition of the GTL liquid for all the oils. This effect was attributed to the solvent effect of the low molecular weight-paraffinic GTL liquid on the crude oils. The weight percent solid precipitated that was estimated as a function of temperature did not show a uniform trend for the set of crude oils. The asphaltene onset studies done on the blends with near-infrared spectroscopy indicated that the addition of GTL liquid could have a stabilizing effect on the asphaltenes in some oils. Analytical techniques such as distillation, solvent separation, HPLC, GC, and GPC were used to obtain detailed composition data on the samples. Two sets of compositional data with 49 and 86 pseudo-components were used to describe the three crude oils used in the blending work. The wax precipitation was calculated using a thermodynamic model based on a modified regular solution theory. A study was done to test the sensitivity of the thermodynamic model to varying levels of crude oil characterization input data for a fourth crude oil sample. The differentiation of the solute fraction (C25+) into the normal alkane, non-n-alkane and the aromatic fractions was found to be important for improving the predictive accuracy of the model. The n-alkane and non-n-alkane distribution used in the modeling of wax precipitation for the three crude oils blended with the GTL liquid gave the WPT's that agreed to within 5% of the experimental values. The precipitated solid amounts were overestimated using this method.

Precipitation information from GNSS Polarimetric Radio Occultation observations

NASA Astrophysics Data System (ADS)

Padulles, R.; Cardellach, E.; Turk, J.; Tomás, S.; Ao, C. O.; de la Torre-Juárez, M.

2017-12-01

There is currently a gap in satellite observations of the moisture structure during heavy precipitation conditions, since infrared and microwave sounders cannot sense water vapor structure near the surface in the presence of intense precipitation. Conversely, Global Navigation Satellite System (GNSS) Radio Occultations (RO) can profile the moisture structure with high precision and vertical resolution, but cannot directly indicate the presence of precipitation. Polarimetric RO (PRO) measurements have been proposed as a method to characterize heavy rain in GNSS RO, by measuring the polarimetric differential phase delay induced by large size hydrometeors. The PRO concept will be tested from space for the first time on board the Spanish PAZ satellite, planned for launch by the end of 2017. Therefore, for the first time ever, GNSS RO measurements will be taken at two polarizations, to exploit the potential capabilities of polarimetric RO for detecting and quantifying heavy precipitation events. If the concept is proved, PAZ will mean a new application of the GNSS Radio-Occultation observations, by providing coincident thermodynamic and precipitation information with high vertical resolution within regions with thick clouds. Before the launch, a series of studies have been performed in order to assess the retrieval of precipitation information from the polarimetric observations. These studies have been based on coincident observations from the COSMIC / FORMOSAT-3 RO satellite constellation, and TRMM and GPM missions. This massive collocation exercise allowed us to build a series of Look Up Tables that relate probabilistically the precipitation intensity to the polarimetric observables. Such studies needed a previous characterization of the polarimetric observable, since it contains contributions from the ionosphere and the emitting and receiving systems. For this purpose, complete end-to-end simulations have been performed, where information from the ionospheric state, the Earth magnetic field, the along-ray precipitation, the impurities at emission, and the effects introduced by the receiver have been taken into account. The results of the simulations and the expected PRO products (vertical profiles of precipitation information and thermodynamic parameters) will be presented here.

Interaction of bovine gallbladder mucin and calcium-binding protein: effects on calcium phosphate precipitation.

PubMed

Afdhal, N H; Ostrow, J D; Koehler, R; Niu, N; Groen, A K; Veis, A; Nunes, D P; Offner, G D

1995-11-01

Gallstones consist of calcium salts and cholesterol crystals, arrayed on a matrix of gallbladder mucin (GBM), and regulatory proteins like calcium-binding protein (CBP). To determine if interactions between CBP and GBM follow a biomineralization scheme, their mutual binding and effects on CaHPO4 precipitation were studied. Binding of CBP to GBM was assessed by inhibition of the fluorescence of the complex of GBM with bis-1,8-anilinonaphthalene sulfonic acid (bis-ANS). The effects of the proteins on precipitation of CaHPO4 were assessed by nephelometry and gravimetry. Precipitates were analyzed for calcium, phosphate, and protein. CBP and bis-ANS competitively displaced each other from 30 binding sites on mucin, with a 1:1 stoichiometry and similar affinity. The rate of precipitation of CaHPO4 was retarded by mucin and CBP. Precipitate mass was unaffected by GBM alone but decreased with the addition of CBP. Complexing CBP with GBM abolished or moderated this latter effect, altered precipitate morphology, and changed the stoichiometric ratios of Ca to PO4 in the precipitates from 1:1 to 3:2. Mucin and CBP were incorporated into the precipitates. These studies suggest that the formation of calcium-containing gallstones is a biomineralization process regulated by both GBM and CBP.

The contributions of local and remote atmospheric moisture fluxes to East Asian precipitation and its variability

NASA Astrophysics Data System (ADS)

Guo, Liang; Klingaman, Nicholas P.; Demory, Marie-Estelle; Vidale, Pier Luigi; Turner, Andrew G.; Stephan, Claudia C.

2018-01-01

We investigate the contribution of the local and remote atmospheric moisture fluxes to East Asia (EA) precipitation and its interannual variability during 1979-2012. We use and expand the Brubaker et al. (J Clim 6:1077-1089,1993) method, which connects the area-mean precipitation to area-mean evaporation and the horizontal moisture flux into the region. Due to its large landmass and hydrological heterogeneity, EA is divided into five sub-regions: Southeast (SE), Tibetan Plateau (TP), Central East (CE), Northwest (NW) and Northeast (NE). For each region, we first separate the contributions to precipitation of local evaporation from those of the horizontal moisture flux by calculating the precipitation recycling ratio: the fraction of precipitation over a region that originates as evaporation from the same region. Then, we separate the horizontal moisture flux across the region's boundaries by direction. We estimate the contributions of the horizontal moisture fluxes from each direction, as well as the local evaporation, to the mean precipitation and its interannual variability. We find that the major contributors to the mean precipitation are not necessarily those that contribute most to the precipitation interannual variability. Over SE, the moisture flux via the southern boundary dominates the mean precipitation and its interannual variability. Over TP, in winter and spring, the moisture flux via the western boundary dominates the mean precipitation; however, variations in local evaporation dominate the precipitation interannual variability. The western moisture flux is the dominant contributor to the mean precipitation over CE, NW and NE. However, the southern or northern moisture flux or the local evaporation dominates the precipitation interannual variability over these regions, depending on the season. Potential mechanisms associated with interannual variability in the moisture flux are identified for each region. The methods and results presented in this study can be readily applied to model simulations, to identify simulation biases in precipitation that relate to the simulated moisture supplies and transport.

Probabilistic precipitation and temperature downscaling of the Twentieth Century Reanalysis over France

NASA Astrophysics Data System (ADS)

Caillouet, Laurie; Vidal, Jean-Philippe; Sauquet, Eric; Graff, Benjamin

2015-04-01

This work proposes a daily high-resolution probabilistic reconstruction of precipitation and temperature fields in France over the last century built on the NOAA 20th century global extended atmospheric reanalysis (20CR, Compo et al., 2011). It aims at delivering appropriate meteorological forcings for continuous distributed hydrological modelling over the last 140 years. The longer term objective is to improve our knowledge of major historical hydrometeorological events having occurred outside of the last 50-year period, over which comprehensive reconstructions and observations are available. It would constitute a perfect framework for assessing the recent observed events but also future events projected by climate change impact studies. The Sandhy (Stepwise ANalogue Downscaling method for Hydrology) statistical downscaling method (Radanovics et al., 2013), initially developed for quantitative precipitation forecast, is used here to bridge the scale gap between 20CR predictors - temperature, geopotential shape, vertical velocity and relative humidity - and local predictands - precipitation and temperature - relevant for catchment-scale hydrology. Multiple predictor domains for geopotential shape are retained from a local optimisation over France using the Safran near-surface reanalysis (Vidal et al., 2010). Sandhy gives an ensemble of 125 equally plausible gridded precipitation and temperature time series over the whole 1871-2012 period. Previous studies showed that Sandhy precipitation outputs are very slightly biased at the annual time scale. Nevertheless, the seasonal precipitation signal for areas with a high interannual variability is not well simulated. Moreover, winter and summer temperatures are respectively over- and underestimated. Reliable seasonal precipitation and temperature signals are however necessary for hydrological modelling, especially for evapotranspiration and snow accumulation/snowmelt processes. Two different post-processing methods are considered to correct monthly precipitation and temperature time series. The first one applies two new analogy steps, using the sea surface temperature (SST) and the large-scale two-meter temperature. The second method is a calendar selection that keeps the closest analogue dates in the year for each target date. A sensitivity study has been performed to assess the final number of analogues dates to retain for each method. A comparison to Safran over 1958-2010 shows that biases on the interannual cycle of precipitation and temperature are strongly reduced with both methods. Using two supplementary analogy levels moreover leads to a large improvement of correlation in seasonal temperature time series. These two methods have also been validated before 1958 thanks to both raw observations and homogenized time series. The two post-processing methods come with some advantages and drawbacks. The calendar selection allows to slightly better correct for seasonal biases in precipitation and is therefore adapted in a forecasting context. The selection with two supplementary analogy levels would allow for possible season shifts and SST trends and is therefore better suited for climate reconstruction and climate change studies. Compo, G. P. et al. (2011). The Twentieth Century Reanalysis Project. Quarterly Journal of the Royal Meteorological Society, 137:1-28. doi: 10.1002/qj.776 Radanovics, S., Vidal, J.-P., Sauquet, E., Ben Daoud, A., and Bontron, G. (2013). Optimising predictor domains for spatially coherent precipitation downscaling. Hydrology and Earth System Sciences, 17:4189-4208. doi:10.5194/hess-17-4189-2013 Vidal, J.-P ., Martin, E., Franchistéguy, L., Baillon, M., and Soubeyroux, J.-M. (2010). A 50-year high-resolution atmospheric reanalysis over France with the Safran system. International Journal of Climatology, 30:1627-1644. doi:10.1002/joc.2003

Diagnosis of inconsistencies in multi-year gridded precipitation data over mountainous areas and related impacts on hydrologic simulations

NASA Astrophysics Data System (ADS)

Mizukami, N.; Smith, M. B.

2010-12-01

It is common for the error characteristics of long-term precipitation data to change over time due to various factors such as gauge relocation and changes in data processing methods. The temporal consistency of precipitation data error characteristics is as important as data accuracy itself for hydrologic model calibration and subsequent use of the calibrated model for streamflow prediction. In mountainous areas, the generation of precipitation grids relies on sparse gage networks, the makeup of which often varies over time. This causes a change in error characteristics of the long-term precipitation data record. We will discuss the diagnostic analysis of the consistency of gridded precipitation time series and illustrate the adverse effect of inconsistent precipitation data on a hydrologic model simulation. We used hourly 4 km gridded precipitation time series over a mountainous basin in the Sierra Nevada Mountains of California from October 1988 through September 2006. The basin is part of the broader study area that served as the focus of the second phase of the Distributed Model Intercomparison Project (DMIP-2), organized by the U.S. National Weather Service (NWS) of the National Oceanographic and Atmospheric Administration (NOAA). To check the consistency of the gridded precipitation time series, double mass analysis was performed using single pixel and basin mean areal precipitation (MAP) values derived from gridded DMIP-2 and Parameter-Elevation Regressions on Independent Slopes Model (PRISM) precipitation data. The analysis leads to the conclusion that over the entire study time period, a clear change in error characteristics in the DMIP-2 data occurred in the beginning of 2003. This matches the timing of one of the major gage network changes. The inconsistency of two MAP time series computed from the gridded precipitation fields over two elevation zones was corrected by adjusting hourly values based on the double mass analysis. We show that model simulations using the adjusted MAP data produce improved stream flow compared to simulations using the inconsistent MAP input data.

Fracture sealing caused by mineral precipitation: The role of aperture and mineral heterogeneity on precipitation-induced permeability loss

NASA Astrophysics Data System (ADS)

Jones, T.; Detwiler, R. L.

2017-12-01

Fractures act as dominant pathways for fluid flow in low-permeability rocks. However, in many subsurface environments, fluid rock reactions can lead to mineral precipitation, which alters fracture surface geometry and reduces fracture permeability. In natural fractures, surface mineralogy and roughness are often heterogeneous, leading to variations in both velocity and reactive surface area. The combined effects of surface roughness and mineral heterogeneity can lead to large disparities in local precipitation rates that are difficult to predict due to the strong coupling between dissolved mineral transport and reactions at the fracture surface. Recent experimental observations suggest that mineral precipitation in a heterogeneous fracture may promote preferential flow and focus large dissolved ion concentrations into regions with limited reactive surface area. Here, we build on these observations using reactive transport simulations. Reactive transport is simulated with a quasi-steady-state 2D model that uses a depth-averaged mass-transfer relationship to describe dissolved mineral transport across the fracture aperture and local precipitation reactions. Mineral precipitation-induced changes to fracture surface geometry are accounted for using two different approaches: (1) by only allowing reactive minerals to grow vertically, and (2) by allowing three-dimensional mineral growth at reaction sites. Preliminary results from simulations using (1) suggest that precipitation-induced aperture reduction focuses flow into thin flow paths. This flow focusing causes a reduction in the fracture-scale precipitation rate, and precipitation ceases when the reaction zone extends the entire length of the fracture. This approach reproduces experimental observations at early time reasonably well, but as precipitation proceeds, reaction sites can grow laterally along the fracture surfaces, which is not predicted by (1). To account for three-dimensional mineral growth (2), we have incorporated a level-set-method based approach for tracking the mineral interfaces in three dimensions. This provides a mechanistic approach for simulating the dynamics of the formation, and eventual closing, of preferential flow paths by precipitation-induced aperture alteration, that do not occur using (1).

A Data Centred Method to Estimate and Map Changes in the Full Distribution of Daily Precipitation and Its Exceedances

NASA Astrophysics Data System (ADS)

Chapman, S. C.; Stainforth, D. A.; Watkins, N. W.

2014-12-01

Estimates of how our climate is changing are needed locally in order to inform adaptation planning decisions. This requires quantifying the geographical patterns in changes at specific quantiles or thresholds in distributions of variables such as daily temperature or precipitation. We develop a method[1] for analysing local climatic timeseries to assess which quantiles of the local climatic distribution show the greatest and most robust changes, to specifically address the challenges presented by 'heavy tailed' distributed variables such as daily precipitation. We extract from the data quantities that characterize the changes in time of the likelihood of daily precipitation above a threshold and of the relative amount of precipitation in those extreme precipitation days. Our method is a simple mathematical deconstruction of how the difference between two observations from two different time periods can be assigned to the combination of natural statistical variability and/or the consequences of secular climate change. This deconstruction facilitates an assessment of how fast different quantiles of precipitation distributions are changing. This involves both determining which quantiles and geographical locations show the greatest change but also, those at which any change is highly uncertain. We demonstrate this approach using E-OBS gridded data[2] timeseries of local daily precipitation from specific locations across Europe over the last 60 years. We treat geographical location and precipitation as independent variables and thus obtain as outputs the pattern of change at a given threshold of precipitation and with geographical location. This is model- independent, thus providing data of direct value in model calibration and assessment. Our results identify regionally consistent patterns which, dependent on location, show systematic increase in precipitation on the wettest days, shifts in precipitation patterns to less moderate days and more heavy days, and drying across all days which is of potential value in adaptation planning. [1] S C Chapman, D A Stainforth, N W Watkins, 2013 Phil. Trans. R. Soc. A, 371 20120287; D. A. Stainforth, S. C. Chapman, N. W. Watkins, 2013 Environ. Res. Lett. 8, 034031 [2] Haylock et al. 2008 J. Geophys. Res (Atmospheres), 113, D20119

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yuan; Ma, Po-Lun; Jiang, Jonathan H.

The attribution of the widely observed shifted precipitation extremes to different forcing agents represents a critical issue for understanding of changes in the hydrological cycle. To compare aerosol and greenhouse-gas effects on the historical trends of precipitation intensity, we performed AMIP-style NCAR/DOE CAM5 model simulations from 1950-2005 with and without anthropogenic aerosol forcings. Precipitation rates at every time step in CAM5 are used to construct precipitation probability distribution functions. By contrasting the two sets of experiments, we found that the global warming induced by the accumulating greenhouse gases is responsible for the changes in precipitation intensity at the global scale.more » However, regionally over the Eastern China, the drastic increase in anthropogenic aerosols primarily accounts for the observed light precipitation suppression since the 1950s. Compared with aerosol radiative effects, aerosol microphysical effect has a predominant role in determining the historical trends of precipitation intensity in Eastern China.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Xi; Blue Sky Technology Corporation, Beijing 100083; Ma, Hongwen, E-mail: mahw@cugb.edu.cn

Highlights: • We use the anti-drop precipitation method for synthesis of magnesium hydroxide. • Boron mud which is solid waste from a borax factory is used as the magnesium source. • The magnesium hydroxide nanoflowers are prepared in a short time. • The as-prepared magnesium hydroxide can be used as an effective flame retardant. - Abstract: Using boron mud as the starting material, the flower-like magnesium hydroxide (MH) has been successfully prepared via anti-drop precipitation method. The effect of NH{sub 3}·H{sub 2}O concentration, aging time, and surfactant on the morphology of MH was investigated. The optimum precipitation conditions are droppingmore » MgSO{sub 4} solution in 5% NH{sub 3}·H{sub 2}O solution, with 3% polyethylene glycol as surfactant, aging for 30 min. XRD, SEM, FI-IR, and TG/DTA have been employed to characterize the as-prepared samples. XRD reveals that MH with high purity has the brucite structure. SEM images show that the flower-like MH exists in the form of mono-disperse well uniform spherical aggregation with diameter of 3–5 μm. TG/DTA shows a total percentage of weight loss 33.6% with a well-defined endothermic peak near 381.3 °C corresponding to the decomposition of MH. Furthermore, it reports that the extremely fast primary nucleation is of significance for crystal growth of MH.« less

Effects of nitrogen in shielding gas on microstructure evolution and localized corrosion behavior of duplex stainless steel welding joint

NASA Astrophysics Data System (ADS)

Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Zhou, Chao

2017-05-01

The effects of nitrogen addition in shielding gas on microstructure evolution and localized corrosion behavior of duplex stainless steel (DSS) welds were studied. N2-supplemented shielding gas facilitated the primary austenite formation, suppressed the Cr2N precipitation in weld root, and increased the microhardnesses of weld metal. Furthermore, N2-supplemented shielding gas increased pitting resistance equivalent number (PREN) of austenite, but which decreased slightly PREN of ferrite. The modified double loop electrochemical potentiokinetic reactivation in 2 M H2SO4 + 1 M HCl was an effective method to study the localized corrosion of the different zones in the DSS welds. The adding 2% N2 to pure Ar shielding gas improved the localized corrosion resistance in the DSS welds, which was due to compensation for nitrogen loss and promoting nitrogen further solution in the austenite phases, suppression of the Cr2N precipitation in the weld root, and increase of primary austenite content with higher PREN than the ferrite and secondary austenite. Secondary austenite are prone to selective corrosion because of lower PREN compared with ferrite and primary austenite. Cr2N precipitation in the pure Ar shielding weld root and heat affected zone caused the pitting corrosion within the ferrite and the intergranular corrosion at the ferrite boundary. In addition, sigma and M23C6 precipitation resulted in the intergranular corrosion at the ferrite boundary.

X-ray Diffraction Investigation of Annealing Behavior of Peened Surface Deformation Layer on Precipitation Hardening Stainless Steel

NASA Astrophysics Data System (ADS)

Huang, Junjie; Wang, Zhou; Gan, Jin; Yang, Ying; Huang, Feng; Wu, Gang; Meng, Qingshuai

2018-05-01

In order to investigate the recrystallization behavior of peened surface deformation layer of precipitation hardening stainless steel, a classic x-ray diffraction line profile analysis, Voigt method, was carried out on peened 17-4PH with different isothermal annealing temperatures. The activation energy of domain boundary migration ( Q a) and the activation energy of microstrain relaxation ( Q b) were calculated by regression analysis in different annealing temperature conditions. The results show that the value of Q a decreases with annealing temperature increasing, which is due to the influence of precipitation (ɛ-Cu) size on the movements of grain and subgrain boundaries. The maximum growth rate of ɛ-Cu particles occurs during 400 to 500 °C interval. Compared with growth behavior of domain size, microstrain relaxation behavior is less sensitive to precipitation particle size. The effects of annealing temperature and time on dislocation density are both significant when annealing temperature is lower than 500 °C. However, the effect of annealing temperature on dislocation density becomes insignificant when annealing temperature is higher than 500 °C. 300 °C annealing temperature only leads to the microstrain relaxation but nearly cannot lead to the domain size growth even if prolonging annealing time. Microstructure enhancement effect still exists in plastic deformation layer when 300 °C annealing temperature lasts for 60 min but nearly disappears when 600 °C annealing temperature lasts for 20 min.

X-ray Diffraction Investigation of Annealing Behavior of Peened Surface Deformation Layer on Precipitation Hardening Stainless Steel

NASA Astrophysics Data System (ADS)

Huang, Junjie; Wang, Zhou; Gan, Jin; Yang, Ying; Huang, Feng; Wu, Gang; Meng, Qingshuai

2018-04-01

In order to investigate the recrystallization behavior of peened surface deformation layer of precipitation hardening stainless steel, a classic x-ray diffraction line profile analysis, Voigt method, was carried out on peened 17-4PH with different isothermal annealing temperatures. The activation energy of domain boundary migration (Q a) and the activation energy of microstrain relaxation (Q b) were calculated by regression analysis in different annealing temperature conditions. The results show that the value of Q a decreases with annealing temperature increasing, which is due to the influence of precipitation (ɛ-Cu) size on the movements of grain and subgrain boundaries. The maximum growth rate of ɛ-Cu particles occurs during 400 to 500 °C interval. Compared with growth behavior of domain size, microstrain relaxation behavior is less sensitive to precipitation particle size. The effects of annealing temperature and time on dislocation density are both significant when annealing temperature is lower than 500 °C. However, the effect of annealing temperature on dislocation density becomes insignificant when annealing temperature is higher than 500 °C. 300 °C annealing temperature only leads to the microstrain relaxation but nearly cannot lead to the domain size growth even if prolonging annealing time. Microstructure enhancement effect still exists in plastic deformation layer when 300 °C annealing temperature lasts for 60 min but nearly disappears when 600 °C annealing temperature lasts for 20 min.

METHOD OF SEPARATION OF PLUTONIUM FROM CARRIER PRECIPITATES

DOEpatents

Dawson, I.R.

1959-09-22

The recovery of plutonium from fluoride carrier precipitates is described. The precipitate is dissolved in zirconyl nitrate, ferric nitrate, aluminum nitrate, or a mixture of these complexing agents, and the plutonium is then extracted from the aqueous solution formed with a water-immiscible organic solvent.

Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

PubMed Central

Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Yang, Qiuhong; Zhou, Chunlin; Zhang, Pande; Mao, Xiaojian; Zhang, Long

2015-01-01

The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders. PMID:28793510

System for recovery of daughter isotopes from a source material

DOEpatents

Tranter, Troy J [Idaho Falls, ID; Todd, Terry A [Aberdeen, ID; Lewis, Leroy C [Idaho Falls, ID; Henscheid, Joseph P [Idaho Falls, ID

2009-08-04

A method of separating isotopes from a mixture containing at least two isotopes in a solution is disclosed. A first isotope is precipitated and is collected from the solution. A daughter isotope is generated and collected from the first isotope. The invention includes a method of producing an actinium-225/bismuth-213 product from a material containing thorium-229 and thorium-232. A solution is formed containing nitric acid and the material containing thorium-229 and thorium-232, and iodate is added to form a thorium iodate precipitate. A supernatant is separated from the thorium iodate precipitate and a second volume of nitric acid is added to the thorium iodate precipitate. The thorium iodate precipitate is stored and a decay product comprising actinium-225 and bismuth-213 is generated in the second volume of nitric acid, which is then separated from the thorium iodate precipitate, filtered, and treated using at least one chromatographic procedure. A system for producing an actinium-225/bismuth-213 product is also disclosed.

Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method.

PubMed

Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Yang, Qiuhong; Zhou, Chunlin; Zhang, Pande; Mao, Xiaojian; Zhang, Long

2015-08-19

The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG) powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC) was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h) with high terminal pH value (>7.80) resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders.

Preparation of nanoparticles of poorly water-soluble antioxidant curcumin by antisolvent precipitation methods

NASA Astrophysics Data System (ADS)

Kakran, Mitali; Sahoo, Nanda Gopal; Tan, I.-Lin; Li, Lin

2012-03-01

The objective of this study was to enhance the solubility and dissolution rate of a poorly water-soluble antioxidant, curcumin, by fabricating its nanoparticles with two methods: antisolvent precipitation with a syringe pump (APSP) and evaporative precipitation of nanosuspension (EPN). For APSP, process parameters like flow rate, stirring speed, solvent to antisolvent (SAS) ratio, and drug concentration were investigated to obtain the smallest particle size. For EPN, factors like drug concentration and the SAS ratio were examined. The effects of these process parameters on the supersaturation, nucleation, and growth rate were studied and optimized to obtain the smallest particle size of curcumin by both the methods. The average particle size of the original drug was about 10-12 μm and it was decreased to a mean diameter of 330 nm for the APSP method and to 150 nm for the EPN method. Overall, decreasing the drug concentration or increasing the flow rate, stirring rate, and antisolvent amount resulted in smaller particle sizes. Differential scanning calorimetry studies suggested lower crystallinity of curcumin particles fabricated. The solubility and dissolution rates of the prepared curcumin particles were significantly higher than those the original curcumin. The antioxidant activity, studied by the DPPH free radical-scavenging assay, was greater for the curcumin nanoparticles than the original curcumin. This study demonstrated that both the methods can successfully prepare curcumin into submicro to nanoparticles. However, drug particles prepared by EPN were smaller than those by APSP and hence, showed the slightly better solubility, dissolution rate, and antioxidant activity than the latter.

Comparing Evaporative Sources of Terrestrial Precipitation and Their Extremes in MERRA Using Relative Entropy

NASA Technical Reports Server (NTRS)

Dirmeyer, Paul A.; Wei, Jiangfeng; Bosilovich, Michael G.; Mocko, David M.

2014-01-01

A quasi-isentropic back trajectory scheme is applied to output from the Modern Era Retrospective-analysis for Research and Applications and a land-only replay with corrected precipitation to estimate surface evaporative sources of moisture supplying precipitation over every ice-free land location for the period 1979-2005. The evaporative source patterns for any location and time period are effectively two dimensional probability distributions. As such, the evaporative sources for extreme situations like droughts or wet intervals can be compared to the corresponding climatological distributions using the method of relative entropy. Significant differences are found to be common and widespread for droughts, but not wet periods, when monthly data are examined. At pentad temporal resolution, which is more able to isolate floods and situations of atmospheric rivers, values of relative entropy over North America are typically 50-400 larger than at monthly time scales. Significant differences suggest that moisture transport may be the key to precipitation extremes. Where evaporative sources do not change significantly, it implies other local causes may underlie the extreme events.

Quasi-relativistic electron precipitation due to interactions with coherent VLF waves in the magnetosphere

NASA Technical Reports Server (NTRS)

Chang, H. C.; Inan, U. S.

1983-01-01

The equations of motion for the cyclotron resonance interaction between coherent whistler mode waves and energetic particles are rederived with the inclusion of relativistic effects. The pitch angle scattering of the near-loss-cone quasi-relativistic electrons trapped in the magnetosphere is studied using a test particle method employing these relativistic equations, and the precipitated energy spectrum due to the wave-induced perturbations of a full distribution of particles is computed. Results show that the full width at half maximum peak width of the rms scattering pattern of the near-loss-cone particles would give an upper bound to the peak width of the associated precipitated energy spectrum under the conditions of moderate wave intensities in the low L shell region. In addition, it is found that the peak widths are within the upper limit values measured by recent satellite experiments. It is concluded that interactions of inner radiation belt particles with monochromatic waves could produce precipitated fluxes with relatively sharp spectral widths, and that therefore the L-dependent narrow peaks observed by low altitude satellite particle detectors could be caused by such interactions.

Sensitivity of Asian Summer Monsoon precipitation to tropical sea surface temperature anomalies

NASA Astrophysics Data System (ADS)

Fan, Lei; Shin, Sang-Ik; Liu, Zhengyu; Liu, Qinyu

2016-10-01

Sensitivity of Asian Summer Monsoon (ASM) precipitation to tropical sea surface temperature (SST) anomalies was estimated from ensemble simulations of two atmospheric general circulation models (GCMs) with an array of idealized SST anomaly patch prescriptions. Consistent sensitivity patterns were obtained in both models. Sensitivity of Indian Summer Monsoon (ISM) precipitation to cooling in the East Pacific was much weaker than to that of the same magnitude in the local Indian-western Pacific, over which a meridional pattern of warm north and cold south was most instrumental in increasing ISM precipitation. This indicates that the strength of the ENSO-ISM relationship is due to the large-amplitude East Pacific SST anomaly rather than its sensitivity value. Sensitivity of the East Asian Summer Monsoon (EASM), represented by the Yangtze-Huai River Valley (YHRV, also known as the meiyu-baiu front) precipitation, is non-uniform across the Indian Ocean basin. YHRV precipitation was most sensitive to warm SST anomalies over the northern Indian Ocean and the South China Sea, whereas the southern Indian Ocean had the opposite effect. This implies that the strengthened EASM in the post-Niño year is attributable mainly to warming of the northern Indian Ocean. The corresponding physical links between these SST anomaly patterns and ASM precipitation were also discussed. The relevance of sensitivity maps was justified by the high correlation between sensitivity-map-based reconstructed time series using observed SST anomaly patterns and actual precipitation series derived from ensemble-mean atmospheric GCM runs with time-varying global SST prescriptions during the same period. The correlation results indicated that sensitivity maps derived from patch experiments were far superior to those based on regression methods.

Spatio-temporal characteristics of the extreme precipitation by L-moment-based index-flood method in the Yangtze River Delta region, China

NASA Astrophysics Data System (ADS)

Yin, Yixing; Chen, Haishan; Xu, Chong-Yu; Xu, Wucheng; Chen, Changchun; Sun, Shanlei

2016-05-01

The regionalization methods, which "trade space for time" by pooling information from different locations in the frequency analysis, are efficient tools to enhance the reliability of extreme quantile estimates. This paper aims at improving the understanding of the regional frequency of extreme precipitation by using regionalization methods, and providing scientific background and practical assistance in formulating the regional development strategies for water resources management in one of the most developed and flood-prone regions in China, the Yangtze River Delta (YRD) region. To achieve the main goals, L-moment-based index-flood (LMIF) method, one of the most popular regionalization methods, is used in the regional frequency analysis of extreme precipitation with special attention paid to inter-site dependence and its influence on the accuracy of quantile estimates, which has not been considered by most of the studies using LMIF method. Extensive data screening of stationarity, serial dependence, and inter-site dependence was carried out first. The entire YRD region was then categorized into four homogeneous regions through cluster analysis and homogenous analysis. Based on goodness-of-fit statistic and L-moment ratio diagrams, generalized extreme-value (GEV) and generalized normal (GNO) distributions were identified as the best fitted distributions for most of the sub-regions, and estimated quantiles for each region were obtained. Monte Carlo simulation was used to evaluate the accuracy of the quantile estimates taking inter-site dependence into consideration. The results showed that the root-mean-square errors (RMSEs) were bigger and the 90 % error bounds were wider with inter-site dependence than those without inter-site dependence for both the regional growth curve and quantile curve. The spatial patterns of extreme precipitation with a return period of 100 years were finally obtained which indicated that there are two regions with highest precipitation extremes and a large region with low precipitation extremes. However, the regions with low precipitation extremes are the most developed and densely populated regions of the country, and floods will cause great loss of human life and property damage due to the high vulnerability. The study methods and procedure demonstrated in this paper will provide useful reference for frequency analysis of precipitation extremes in large regions, and the findings of the paper will be beneficial in flood control and management in the study area.

The effect of precipitation collector design on the measured acid content of precipitation

Treesearch

H. A. Weibe

1976-01-01

In order to evaluate the effect of different types of collectors on the measured chemical constituents of monthly precipitation collections, an array of fourteen precipitation samplers of five different designs has been in operation at Woodbridge, Ontario since March 1974. The collectors are located in an open field near the city of Toronto in an area of approximately...

Method for the preparation of thallium-containing superconducting materials by precipitation

DOEpatents

Bunker, Bruce C.; Lamppa, Diana L.; Voigt, James A.

1991-01-01

This invention provides improved methods for the preparation of precursor powders that are used in the preparation of superconducting ceramic materials that contain thallium. A first solution that contains the hydrogen peroxide and metal cations, other than thallium, that will be part of the ceramic is quickly mixed with a second solution that contains precipitating anions and thallium (I) to form a precipitate which is dried to yield precursor powders. The precursor powders are calcined an sintered to produce superconducting materials that contain thallium.

Sensitivity of WRF precipitation field to assimilation sources in northeastern Spain

NASA Astrophysics Data System (ADS)

Lorenzana, Jesús; Merino, Andrés; García-Ortega, Eduardo; Fernández-González, Sergio; Gascón, Estíbaliz; Hermida, Lucía; Sánchez, José Luis; López, Laura; Marcos, José Luis

2015-04-01

Numerical weather prediction (NWP) of precipitation is a challenge. Models predict precipitation after solving many physical processes. In particular, mesoscale NWP models have different parameterizations, such as microphysics, cumulus or radiation schemes. These facilitate, according to required spatial and temporal resolutions, precipitation fields with increasing reliability. Nevertheless, large uncertainties are inherent to precipitation forecasting. Consequently, assimilation methods are very important. The Atmospheric Physics Group at the University of León in Spain and the Castile and León Supercomputing Center carry out daily weather prediction based on the Weather Research and Forecasting (WRF) model, covering the entire Iberian Peninsula. Forecasts of severe precipitation affecting the Ebro Valley, in the southern Pyrenees range of northeastern Spain, are crucial in the decision-making process for managing reservoirs or initializing runoff models. These actions can avert floods and ensure uninterrupted economic activity in the area. We investigated a set of cases corresponding to intense or severe precipitation patterns, using a rain gauge network. Simulations were performed with a dual objective, i.e., to analyze forecast improvement using a specific assimilation method, and to study the sensitivity of model outputs to different types of assimilation data. A WRF forecast model initialized by an NCEP SST analysis was used as the control run. The assimilation was based on the Meteorological Assimilation Data Ingest System (MADIS) developed by NOAA. The MADIS data used were METAR, maritime, ACARS, radiosonde, and satellite products. The results show forecast improvement using the suggested assimilation method, and differences in the accuracy of forecast precipitation patterns varied with the assimilation data source.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neelgund, Gururaj M.; Oki, Aderemi, E-mail: aroki@pvamu.edu; Luo, Zhiping

Graphical abstract: A facile chemical precipitation method is reported for effective in situ deposition of hydroxyapatite on graphene nanosheets. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. Display Omitted Highlights: ► It is a facile and effective method for deposition of HA on GR nanosheets. ► It avoids the use of harmful reducing agents like hydrazine, NaBH{sub 4} etc. ► GR nanosheets were produced using bio-compatible, ethylenediamine. ► The graphitic structure of synthesized GR nanosheets was high ordered. ► The ratio of Ca to P in HAmore » was 1.64, which is close to ratio in natural bone. -- Abstract: Graphene nanosheets were effectively functionalized by in situ deposition of hydroxyapatite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure.« less

Effects of daily precipitation and evapotranspiration patterns on flow and VOC transport to groundwater along a watershed flow path

USGS Publications Warehouse

Johnson, Richard L.; Thoms, R.B.; Zogorski, J.S.

2003-01-01

MTBE and other volatile organic compounds (VOCs) are widely observed in shallow groundwater in the United States, especially in urban areas. Previous studies suggest that the atmosphere and/or nonpoint surficial sources could be responsible for some of those VOCs, especially in areas where there is net recharge to groundwater. However, in semi-arid locations where annual potential evapotranspiration can exceed annual precipitation, VOC detections in groundwater can be frequent. VOC transport to groundwater under net discharge conditions has not previously been examined. A numerical model is used here to demonstrate that daily precipitation and evapotranspiration (ET) patterns can have a significant effect on recharge to groundwater, water table elevations, and VOC transport. Ten-year precipitation/ET scenarios from six sites in the United States are examined using both actual daily observed values and “average” pulsed precipitation. MTBE and tetrachloroethylene transport, including gas-phase diffusion, are considered. The effects of the precipitation/ET scenarios on net recharge and groundwater flow are significant and complicated, especially under low-precipitation conditions when pulsed precipitation can significantly underestimate transport to groundwater. In addition to precipitation and evapotranspiration effects, location of VOC entry into the subsurface within the watershed is important for transport in groundwater. This is caused by groundwater hydraulics at the watershed scale as well as variations in ET within the watershed. The model results indicate that it is important to consider both daily precipitation/ET patterns and location within the watershed in order to interpret VOC occurrence in groundwater, especially in low-precipitation settings.

Application of deep learning in determining IR precipitation occurrence: a Convolutional Neural Network model

NASA Astrophysics Data System (ADS)

Wang, C.; Hong, Y.

2017-12-01

Infrared (IR) information from Geostationary satellites can be used to retrieve precipitation at pretty high spatiotemporal resolutions. Traditional artificial intelligence (AI) methodologies, such as artificial neural networks (ANN), have been designed to build the relationship between near-surface precipitation and manually derived IR features in products including PERSIANN and PERSIANN-CCS. This study builds an automatic precipitation detection model based on IR data using Convolutional Neural Network (CNN) which is implemented by the newly developed deep learning framework, Caffe. The model judges whether there is rain or no rain at pixel level. Compared with traditional ANN methods, CNN can extract features inside the raw data automatically and thoroughly. In this study, IR data from GOES satellites and precipitation estimates from the next generation QPE (Q2) over the central United States are used as inputs and labels, respectively. The whole datasets during the study period (June to August in 2012) are randomly partitioned to three sub datasets (train, validation and test) to establish the model at the spatial resolution of 0.08°×0.08° and the temporal resolution of 1 hour. The experiments show great improvements of CNN in rain identification compared to the widely used IR-based precipitation product, i.e., PERSIANN-CCS. The overall gain in performance is about 30% for critical success index (CSI), 32% for probability of detection (POD) and 12% for false alarm ratio (FAR). Compared to other recent IR-based precipitation retrieval methods (e.g., PERSIANN-DL developed by University of California Irvine), our model is simpler with less parameters, but achieves equally or even better results. CNN has been applied in computer vision domain successfully, and our results prove the method is suitable for IR precipitation detection. Future studies can expand the application of CNN from precipitation occurrence decision to precipitation amount retrieval.

The Incorporation and Initialization of Cloud Water/ice in AN Operational Forecast Model

NASA Astrophysics Data System (ADS)

Zhao, Qingyun

Quantitative precipitation forecasts have been one of the weakest aspects of numerical weather prediction models. Theoretical studies show that the errors in precipitation calculation can arise from three sources: errors in the large-scale forecasts of primary variables, errors in the crude treatment of condensation/evaporation and precipitation processes, and errors in the model initial conditions. A new precipitation parameterization scheme has been developed to investigate the forecast value of improved precipitation physics via the introduction of cloud water and cloud ice into a numerical prediction model. The main feature of this scheme is the explicit calculation of cloud water and cloud ice in both the convective and stratiform precipitation parameterization. This scheme has been applied to the eta model at the National Meteorological Center. Four extensive tests have been performed. The statistical results showed a significant improvement in the model precipitation forecasts. Diagnostic studies suggest that the inclusion of cloud ice is important in transferring water vapor to precipitation and in the enhancement of latent heat release; the latter subsequently affects the vertical motion field significantly. Since three-dimensional cloud data is absent from the analysis/assimilation system for most numerical models, a method has been proposed to incorporate observed precipitation and nephanalysis data into the data assimilation system to obtain the initial cloud field for the eta model. In this scheme, the initial moisture and vertical motion fields are also improved at the same time as cloud initialization. The physical initialization is performed in a dynamical initialization framework that uses the Newtonian dynamical relaxation method to nudge the model's wind and mass fields toward analyses during a 12-hour data assimilation period. Results from a case study showed that a realistic cloud field was produced by this method at the end of the data assimilation period. Precipitation forecasts have been significantly improved as a result of the improved initial cloud, moisture and vertical motion fields.

A MATHEMATICAL MODEL FOR CALCULATING ELECTRICAL CONDITIONS IN WIRE-DUCT ELECTROSTATIC PRECIPITATION DEVICES

EPA Science Inventory

The article reports the development of a new method of calculating electrical conditions in wire-duct electrostatic precipitation devices. The method, based on a numerical solution to the governing differential equations under a suitable choice of boundary conditions, accounts fo...

Preparation and characterization of nanoparticles of carboxymethyl cellulose acetate butyrate containing acyclovir

NASA Astrophysics Data System (ADS)

Vedula, Venkata Bharadwaz; Chopra, Maulick; Joseph, Emil; Mazumder, Sonal

2016-02-01

Nanoparticles of carboxymethyl cellulose acetate butyrate complexed with the poorly soluble antiviral drug acyclovir (ACV) were produced by precipitation process and the formulation process and properties of nanoparticles were investigated. Two different particle synthesis methods were explored—a conventional precipitation method and a rapid precipitation in a multi-inlet vortex mixer. The particles were processed by rotavap followed by freeze-drying. Particle diameters as measured by dynamic light scattering were dependent on the synthesis method used. The conventional precipitation method did not show desired particle size distribution, whereas particles prepared by the mixer showed well-defined particle size ~125-450 nm before and after freeze-drying, respectively, with narrow polydispersity indices. Fourier transform infrared spectroscopy showed chemical stability and intactness of entrapped drug in the nanoparticles. Differential scanning calorimetry showed that the drug was in amorphous state in the polymer matrix. ACV drug loading was around 10 wt%. The release studies showed increase in solution concentration of drug from the nanoparticles compared to the as-received crystalline drug.

Linking sediment-charcoal records and ecological modeling to understand causes of fire-regime change in boreal forests.

PubMed

Brubaker, Linda B; Higuera, Philip E; Rupp, T Scott; Olson, Mark A; Anderson, Patricia M; Hu, Feng Sheng

2009-07-01

Interactions between vegetation and fire have the potential to overshadow direct effects of climate change on fire regimes in boreal forests of North America. We develop methods to compare sediment-charcoal records with fire regimes simulated by an ecologica model, ALFRESCO (Alaskan Frame-based Ecosystem Code) and apply these methods to evaluate potential causes of a mid-Holocene fire-regime shift in boreal forests of the south-central Brooks Range, Alaska, U.S.A. Fire-return intervals (FRIs, number of years between fires) are estimated over the past 7000 calibrated 14C years (7-0 kyr BP [before present]) from short-term variations in charcoal accumulation rates (CHARs) at three lakes, and an index of area burned is inferred from long-term CHARs at these sites. ALFRESCO simulations of FRIs and annual area burned are based on prescribed vegetation and climate for 7-5 kyr BP and 5-0 kyr BP, inferred from pollen and stomata records and qualitative paleoclimate proxies. Two sets of experiments examine potential causes of increased burning between 7-5 and 5-0 kyr BP. (1) Static-vegetation scenarios: white spruce dominates with static mean temperature and total precipitation of the growing season for 7-0 kyr BP or with decreased temperature and/or increased precipitation for 5-0 kyr BP. (2) Changed-vegetation scenarios: black spruce dominates 5-0 kyr BP, with static temperature and precipitation or decreased temperature and/or increased precipitation. Median FRIs decreased between 7-5 and 5-0 kyr BP in empirical data and changed-vegetation scenarios but remained relatively constant in static-vegetation scenarios. Median empirical and simulated FRIs are not statistically different for 7-5 kyr BP and for two changed-vegetation scenarios (temperature decrease, precipitation increase) for 5-0 kyr BP. In these scenarios, cooler temperatures or increased precipitation dampened the effect of increased landscape flammability resulting from the increase in black spruce. CHAR records and all changed-vegetation scenarios indicate long-term increases in area burned between 7-5 and 5-0 kyr BP. The similarity of CHAR and ALFRESCO results demonstrates the compatibility of these independent data sets for investigating ecological mechanisms causing past fire-regime changes. The finding that vegetation flammability was a major driver of Holocene fire regimes is consistent with other investigations that suggest that landscape fuel characteristics will mediate the direct effects of future climate change on boreal fire regimes.

A microwave backscattering model for precipitation

NASA Astrophysics Data System (ADS)

Ermis, Seda

A geophysical microwave backscattering model for space borne and ground-based remote sensing of precipitation is developed and used to analyze backscattering measurements from rain and snow type precipitation. Vector Radiative Transfer (VRT) equations for a multilayered inhomogeneous medium are applied to the precipitation region for calculation of backscattered intensity. Numerical solution of the VRT equation for multiple layers is provided by the matrix doubling method to take into account close range interactions between particles. In previous studies, the VRT model was used to calculate backscattering from a rain column on a sea surface. In the model, Mie scattering theory for closely spaced scatterers was used to determine the phase matrix for each sublayer characterized by a set of parameters. The scatterers i.e. rain drops within the sublayers were modelled as spheres with complex permittivities. The rain layer was bounded by rough boundaries; the interface between the cloud and the rain column as well as the interface between the sea surface and the rain were all analyzed by using the integral equation model (IEM). Therefore, the phase matrix for the entire rain column was generated by the combination of surface and volume scattering. Besides Mie scattering, in this study, we use T-matrix approach to examine the effect of the shape to the backscattered intensities since larger raindrops are most likely oblique in shape. Analyses show that the effect of obliquity of raindrops to the backscattered wave is related with size of the scatterers and operated frequency. For the ground-based measurement system, the VRT model is applied to simulate the precipitation column on horizontal direction. Therefore, the backscattered reflectivities for each unit range of volume are calculated from the backscattering radar cross sections by considering radar range and effective illuminated area of the radar beam. The volume scattering phase matrices for each range interval are calculated by Mie scattering theory. VRT equations are solved by matrix doubling method to compute phase matrix for entire radar beam. Model results are validated with measured data by X-band dual polarization Phase Tilt Weather Radar (PTWR) for snow, rain, wet hail type precipitation. The geophysical parameters given the best fit with measured reflectivities are used in previous models i.e. Rayleigh Approximation and Mie scattering and compared with the VRT model. Results show that reflectivities calculated by VRT models are differed up to 10 dB from the Rayleigh approximation model and up to 5 dB from the Mie Scattering theory due to both multiple scattering and attenuation losses for the rain rates as high as 80 mm/h.

Effects of Heparin and ε-Aminocaproic Acid in Dogs on Plasmin- 125I Generation in Response to Urokinase Injections and Venous Injury

PubMed Central

Takeda, Y.; Parkhill, T. R.; Nakabayashi, M.

1972-01-01

The isotopic method described previously for quantification of plasmin- 125I by disc gel electrophoresis was modified by inclusion of euglobulin precipitation to expand its applicability to plasmas containing low radioactivity of plasmin- 125I and plasminogen- 125I. It was found that the euglobulin precipitation method precipitates 72.4±2.1 (sd)% of both plasmin- 125I and plasminogen- 125I. Using this method and plasminogen- 125I as a tracer, studies were first made of the effects of heparin and ε-aminocaproic acid in dogs on plasmin- 125I generation in responese to a single injection of urokinase and to venous injury; second, of the effects of venous occlusion and thrombosis on plasmin- 125I generation; and third, in vitro studies of plasminogen- 125I affinity to fibrin and its activation in blood clots. The venous injury was produced by the damage of venous endothelium by an injection of 90% phenol and the thrombosis by a thrombin injection into an occluded vein. Heparin and ε-aminocaproic acid under the present experimental conditions inhibited about 78 and 100%, respectively of plasmin- 125I generation by the urokinase injection. Similar inhibitory effects of heparin and ε-aminocaproic acid were observed on plasmin- 125I generation in response to venous injury. The venous occlusion caused a small degree of plasmin- 125I generation, but thrombin thrombosis did not seem to stimulate the generation of plasmin- 125I. The in vitro studies showed that plasminogen- 125I does not have a specific affinity to fibrin and is incorporated into blood clots in approximately equal concentrations as those in serum during clotting processes, and that blood clots per se do not stimulate plasmin- 125I generation. These results suggest that injured veins release considerable amounts of vascular plasminogen activators into circulation and that these play an important role in thrombus dissolution in vivo. PMID:4262519

Dimension reduction method for SPH equations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tartakovsky, Alexandre M.; Scheibe, Timothy D.

2011-08-26

Smoothed Particle Hydrodynamics model of a complex multiscale processe often results in a system of ODEs with an enormous number of unknowns. Furthermore, a time integration of the SPH equations usually requires time steps that are smaller than the observation time by many orders of magnitude. A direct solution of these ODEs can be extremely expensive. Here we propose a novel dimension reduction method that gives an approximate solution of the SPH ODEs and provides an accurate prediction of the average behavior of the modeled system. The method consists of two main elements. First, effective equationss for evolution of averagemore » variables (e.g. average velocity, concentration and mass of a mineral precipitate) are obtained by averaging the SPH ODEs over the entire computational domain. These effective ODEs contain non-local terms in the form of volume integrals of functions of the SPH variables. Second, a computational closure is used to close the system of the effective equations. The computational closure is achieved via short bursts of the SPH model. The dimension reduction model is used to simulate flow and transport with mixing controlled reactions and mineral precipitation. An SPH model is used model transport at the porescale. Good agreement between direct solutions of the SPH equations and solutions obtained with the dimension reduction method for different boundary conditions confirms the accuracy and computational efficiency of the dimension reduction model. The method significantly accelerates SPH simulations, while providing accurate approximation of the solution and accurate prediction of the average behavior of the system.« less

Detection of the relationship between peak temperature and extreme precipitation

NASA Astrophysics Data System (ADS)

Yu, Y.; Liu, J.; Zhiyong, Y.

2017-12-01

Under the background of climate change and human activities, the characteristics and pattern of precipitation have changed significantly in many regions. As the political and cultural center of China, the structure and character of precipitation in Jingjinji District has varied dramatically in recent years. In this paper, the daily precipitation data throughout the period 1960-2013 are selected for analyzing the spatial-temporal variability of precipitation. The results indicate that the frequency and intensity of precipitation presents an increasing trend. Based on the precipitation data, the maximum, minimum and mean precipitation in different temporal and spatial scales is calculated respectively. The temporal and spatial variation of temperature is obtained by using statistical methods. The relationship between temperature and precipitation in different range is analyzed. The curve relates daily precipitation extremes with local temperatures has a peak structure, increasing at the low-medium range of temperature variations but decreasing at high temperatures. The relationship between extreme precipitation is stronger in downtown than that in suburbs.

The theory, direction, and magnitude of ecosystem fire probability as constrained by precipitation and temperature.

PubMed

Guyette, Richard; Stambaugh, Michael C; Dey, Daniel; Muzika, Rose Marie

2017-01-01

The effects of climate on wildland fire confronts society across a range of different ecosystems. Water and temperature affect the combustion dynamics, irrespective of whether those are associated with carbon fueled motors or ecosystems, but through different chemical, physical, and biological processes. We use an ecosystem combustion equation developed with the physical chemistry of atmospheric variables to estimate and simulate fire probability and mean fire interval (MFI). The calibration of ecosystem fire probability with basic combustion chemistry and physics offers a quantitative method to address wildland fire in addition to the well-studied forcing factors such as topography, ignition, and vegetation. We develop a graphic analysis tool for estimating climate forced fire probability with temperature and precipitation based on an empirical assessment of combustion theory and fire prediction in ecosystems. Climate-affected fire probability for any period, past or future, is estimated with given temperature and precipitation. A graphic analyses of wildland fire dynamics driven by climate supports a dialectic in hydrologic processes that affect ecosystem combustion: 1) the water needed by plants to produce carbon bonds (fuel) and 2) the inhibition of successful reactant collisions by water molecules (humidity and fuel moisture). These two postulates enable a classification scheme for ecosystems into three or more climate categories using their position relative to change points defined by precipitation in combustion dynamics equations. Three classifications of combustion dynamics in ecosystems fire probability include: 1) precipitation insensitive, 2) precipitation unstable, and 3) precipitation sensitive. All three classifications interact in different ways with variable levels of temperature.

Investigation and modeling of Al3(Sc, Zr) precipitation strengthening in the presence of enhanced supersaturation and within Al-Cu binary alloys

NASA Astrophysics Data System (ADS)

Deane, Kyle

Diffuse Al-Sc and Al-Zr alloys have been demonstrated in literature to be relatively coarsening resistant at higher temperatures when compared with commonly used precipitation strengthening alloys (e.g. 2000 series, 6000 series). However, because of a limited strengthening due to the low solubility of scandium and zirconium in aluminum, and owing to the scarcity and therefore sizeable price tag attached to scandium, little research has been done in the way of optimizing these alloys for commercial applications. With this in mind, this dissertation describes research which aims to tackle several important areas of Al-Sc-Zr research that have been yet unresolved. In Chapter 4, rapid solidification was utilized to enhance the achievable supersaturation of the alloy in an effort to increase the achievable precipitate strengthening. In Chapter 5, Additive Friction Stir processing (AFS), a novel method of mechanically combining materials without melting, was employed in an attempt to pass the benefits of supersaturation from melt spun ribbon into a more structurally useful bulk material. In Chapter 6, a Matlab program written to predict precipitate nucleation, growth, and coarsening with a modified Kampmann and Wagner Numerical (KWN) model, was used to predict heat treatment regimens for more efficient strengthening. Those predictions were then tested experimentally to test the validity of the results. And lastly, in Chapter 7, the effect of zirconium on Al-Cu secondary precipitates was studied in an attempt to increase their thermal stability, as much higher phase fractions of Al-Cu precipitates are achievable than Al-Zr precipitates.

Precipitate Evolution and Strengthening in Supersaturated Rapidly Solidified Al-Sc-Zr Alloys

NASA Astrophysics Data System (ADS)

Deane, Kyle; Kampe, S. L.; Swenson, Douglas; Sanders, P. G.

2017-04-01

Because of the low diffusivities of scandium and zirconium in aluminum, trialuminide precipitates containing these elements have been reported to possess excellent thermal stability at temperatures of 573 K (300 °C) and higher. However, the relatively low equilibrium solubilities of these elements in aluminum limit the achievable phase fraction and, in turn, strengthening contributions from these precipitates. One method of circumventing this limitation involves the use of rapid solidification techniques to suppress the initial formation of precipitates in alloys containing higher solute compositions. This work specifically discusses the fabrication of supersaturated Al-Sc, Al-Zr, and Al-Sc-Zr alloys via melt spinning, in which supersaturations of at least 0.55 at. pct Zr and 0.8 at. pct Sc are shown to be attainable through XRD analysis. The resulting ribbons were subjected to a multistep aging heat treatment in order to encourage a core-shell precipitate morphology, the precipitate evolution behavior was monitored with XRD and TEM, and the aging behavior was observed. While aging in these alloys is shown to follow similar trends to conventionally processed materials reported in literature, with phase fraction increasing until higher aging temperatures causing a competing dissolution effect, the onset of precipitation begins at lower temperatures than previously observed and the peak hardnesses occurred at higher temperature steps due to an increased aging time associated with increased solute concentration. Peaking in strength at a higher temperature doesn't necessarily mean an increase in thermal stability, but rather emphasizes the need for intelligently designed heat treatments to take full advantage of the potential strengthening of supersaturated Al-Sc-Zr alloys.

The theory, direction, and magnitude of ecosystem fire probability as constrained by precipitation and temperature

PubMed Central

Guyette, Richard; Stambaugh, Michael C.; Dey, Daniel

2017-01-01

The effects of climate on wildland fire confronts society across a range of different ecosystems. Water and temperature affect the combustion dynamics, irrespective of whether those are associated with carbon fueled motors or ecosystems, but through different chemical, physical, and biological processes. We use an ecosystem combustion equation developed with the physical chemistry of atmospheric variables to estimate and simulate fire probability and mean fire interval (MFI). The calibration of ecosystem fire probability with basic combustion chemistry and physics offers a quantitative method to address wildland fire in addition to the well-studied forcing factors such as topography, ignition, and vegetation. We develop a graphic analysis tool for estimating climate forced fire probability with temperature and precipitation based on an empirical assessment of combustion theory and fire prediction in ecosystems. Climate-affected fire probability for any period, past or future, is estimated with given temperature and precipitation. A graphic analyses of wildland fire dynamics driven by climate supports a dialectic in hydrologic processes that affect ecosystem combustion: 1) the water needed by plants to produce carbon bonds (fuel) and 2) the inhibition of successful reactant collisions by water molecules (humidity and fuel moisture). These two postulates enable a classification scheme for ecosystems into three or more climate categories using their position relative to change points defined by precipitation in combustion dynamics equations. Three classifications of combustion dynamics in ecosystems fire probability include: 1) precipitation insensitive, 2) precipitation unstable, and 3) precipitation sensitive. All three classifications interact in different ways with variable levels of temperature. PMID:28704457

Historical channel-planform change of the Little Colorado River near Winslow, Arizona

USGS Publications Warehouse

Block, Debra L.

2014-01-01

This study evaluates channel-planform adjustment on an alluvial reach of the Little Colorado River and documents the geomorphic evolution of the channel through an analysis of aerial photographs and orthophotographs for the period 1936–2010. The Little Colorado River has adjusted to the effects of an extreme flood in 1923 and a subsequent decline in peak discharge and mean annual flow by channel narrowing: the channel width and area of the river have decreased by approximately 90 percent over the study period. Although deposition historically exceeds erosion, lateral migration exacerbates localized erosion, particularly near hydraulic controls. Despite repeated cutoff and avulsion, the Little Colorado River has steadily increased in length and sinuosity over a period of 74 years. Changes in temperature and precipitation are likely affecting the discharge of the Little Colorado River near and downstream of Winslow, Ariz. Nonparametric methods of trend detection determine whether the probability distribution of temperature, precipitation, and peak streamflow has changed over time. Time-series plots of temperature and precipitation show statistically significant trends at the 99-percent-confidence level when evaluated with a Mann-Kendall test. An increasing trend was indicated in mean daily minimum air temperature (Tmin), whereas decreasing trends were indicated in both annual precipitation (Pann) and monsoon-seasonal precipitation (Pjas), as well as in peak discharge.

Characterization of mixing of suspension in a mechanically stirred precipitation system

NASA Astrophysics Data System (ADS)

Farkas, B.; Blickle, T.; Ulbert, Zs.; Hasznos-Nezdei, M.

1996-09-01

In the case of precipitational crystallization, the particle size distribution of the resulting product is greatly influenced by the mixing rate of the system. We have worked out a method of characterizing the mixing of precipitated suspensions by applying a function of mean residence time and particle size distribution. For the experiments a precipitated suspension of β-lactam-type antibiotic has been used in a mechanically stirred tank.

Use of the Box-Cox Transformation in Detecting Changepoints in Daily Precipitation Data Series

NASA Astrophysics Data System (ADS)

Wang, X. L.; Chen, H.; Wu, Y.; Pu, Q.

2009-04-01

This study integrates a Box-Cox power transformation procedure into two statistical tests for detecting changepoints in Gaussian data series, to make the changepoint detection methods applicable to non-Gaussian data series, such as daily precipitation amounts. The detection power aspects of transformed methods in a common trend two-phase regression setting are assessed by Monte Carlo simulations for data of a log-normal or Gamma distribution. The results show that the transformed methods have increased the power of detection, in comparison with the corresponding original (untransformed) methods. The transformed data much better approximate to a Gaussian distribution. As an example of application, the new methods are applied to a series of daily precipitation amounts recorded at a station in Canada, showing satisfactory detection power.

Synthesis of Commercial Products from Copper Wire-Drawing Waste

NASA Astrophysics Data System (ADS)

Ayala, J.; Fernández, B.

2014-06-01

Copper powder and copper sulfate pentahydrate were obtained from copper wire-drawing scale. The hydrometallurgical recycling process proposed in this article yields a high-purity copper powder and analytical grade copper sulfate pentahydrate. In the first stage of this process, the copper is dissolved in sulfuric acid media via dismutation of the scale. In the second stage, copper sulfate pentahydrate is precipitated using ethanol. Effects such as pH, reaction times, stirring speed, initial copper concentration, and ethanol/solution volume ratio were studied during the precipitation from solution reaction. The proposed method is technically straightforward and provides efficient recovery of Cu from wire-drawing scale.

Effects of urbanization and stormwater control measures on streamflows in the vicinity of Clarksburg, Maryland, USA

USGS Publications Warehouse

Rhea, Lee; Jarnagin, Taylor; Hogan, Dianna; Loperfido, J. V.; Shuster, William

2015-01-01

Understanding the efficacy of revised watershed management methods is important to mitigating the impacts of urbanization on streamflow. We evaluated the influence of land use change, primarily as urbanization, and stormwater control measures on the relationship between precipitation and stream discharge over an 8-year period for five catchments near Clarksburg, Montgomery County, Maryland, USA. A unit-hydrograph model based on a temporal transfer function was employed to account for and standardize temporal variation in rainfall pattern, and properly apportion rainfall to streamflow at different time lags. From these lagged relationships, we quantified a correction to the precipitation time series to achieve a hydrograph that showed good agreement between precipitation and discharge records. Positive corrections appeared to include precipitation events that were of limited areal extent and therefore not captured by our rain gages. Negative corrections were analysed for potential causal relationships. We used mixed-model statistical techniques to isolate different sources of variance as drivers that mediate the rainfall–runoff dynamic before and after management. Seasonal periodicity mediated rainfall–runoff relationships, and land uses (i.e. agriculture, natural lands, wetlands and stormwater control measures) were statistically significant predictors of precipitation apportionment to stream discharge. Our approach is one way to evaluate actual effectiveness of management efforts in the face of complicating circumstances and could be paired with cost data to understand economic efficiency or life cycle aspects of watershed management. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Effect of the synthesis conditions on the electrochemical properties of LiFePO{sub 4} obtained from NH{sub 4}FePO{sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prosini, Pier Paolo, E-mail: pierpaolo.prosini@enea.it; Gislon, Paola; Cento, Cinzia

Graphical abstract: - Highlights: • Four different samples of FAP were synthesized by precipitation techniques. • The samples were used as precursors to synthesize electrochemical active LiFePO{sub 4}. • Their morphology, composition, structure and electrochemical performance were studied. • The LiFePO{sub 4} electrochemical performance resulted affected by the preparation method - Abstract: In this paper the morphological, structural and electrochemical properties of crystalline lithium iron phosphate (LiFePO{sub 4}) obtained from ferrous ammonium phosphate (FAP) have been studied. The FAP was obtained following four different processes, namely: (1) homogeneous phase precipitation, (2) heterogeneous phase precipitation from stoichiometric sodium phosphate, (3) heterogeneousmore » phase precipitation from stoichiometric ammonium phosphate, and (4) heterogeneous phase precipitation from over stoichiometric ammonium phosphate. Lithium iron phosphate was prepared by solid state reaction of FAP with lithium hydroxide. In order to evaluate the effect of reaction time and synthesis temperature the LiFePO{sub 4} was prepared varying the heating temperatures (550, 600 and 700 °C) and the reaction times (1 or 2 h). The morphology of the materials was evaluated by scanning electron microscopy while the chemical composition was determined by electron energy loss spectroscopy. X-ray diffraction was used to evaluate phase composition, crystal structure and crystallite size. The so obtained LiFePO{sub 4}'s were fully electrochemical characterized and a correlation was found between the crystal size and the electrochemical performance.« less

Estimating preseason irrigation losses by characterizing evaporation of effective precipitation under bare soil conditions using large weighing lysimeters

USDA-ARS?s Scientific Manuscript database

Irrigation scheduling is one of the most cost effective means of conserving limited groundwater resources, particularly in semi-arid regions. Effective precipitation, or the net amount of water from precipitation that can be used in field water balance equations, is essential to accurate and effecti...

Effects of grazing on leaf area index, fractional cover and evapotranspiration by a desert phreatophyte community at a former uranium mill site on the Colorado Plateau.

PubMed

Bresloff, Cynthia J; Nguyen, Uyen; Glenn, Edward P; Waugh, Jody; Nagler, Pamela L

2013-01-15

This study employed ground and remote sensing methods to monitor the effects of grazing on leaf area index (LAI), fractional cover (f(c)) and evapotranspiration (ET) of a desert phreatophyte community over an 11 year period at a former uranium mill site on the Colorado Plateau, U.S. Nitrate, ammonium and sulfate are migrating away from the mill site in a shallow alluvial aquifer. The phreatophyte community, consisting of Atriplex canescens (ATCA) and Sarcobatus vermiculatus (SAVE) shrubs, intercepts groundwater and could potentially slow the movement of the contaminant plume through evapotranspiration (ET). However, the site has been heavily grazed by livestock, reducing plant cover and LAI. We used livestock exclosures and revegetation plots to determine the effects of grazing on LAI, f(c) and ET, then projected the findings over the whole site using multi-platform remote sensing methods. We show that ET is approximately equal to annual precipitation at the site, but when ATCA and SAVE are protected from grazing they can develop high f(c) and LAI values, and ET can exceed annual precipitation, with the excess coming from groundwater discharge. Therefore, control of grazing could be an effective method to slow migration of contaminants at this and similar sites in the western U.S. Copyright © 2012 Elsevier Ltd. All rights reserved.

Method for rapid screening analysis of Sr-90 in edible plant samples collected near Fukushima, Japan.

PubMed

Amano, Hikaru; Sakamoto, Hideaki; Shiga, Norikatsu; Suzuki, Kaori

2016-06-01

A screening method for measuring (90)Sr in edible plant samples by focusing on (90)Y in equilibrium with (90)Sr is reported. (90)Y was extracted from samples with acid, co-precipitated with iron hydroxide, and precipitated with oxalic acid. The dissolved oxalate precipitate was loaded on an extraction chromatography resin, and the (90)Y-enriched eluate was analyzed by Cherenkov counting with a TDCR liquid scintillation counter. (90)Sr ((90)Y) concentration was determined in plant samples collected near the damaged Fukushima Daiichi Nuclear Power Plants with this method. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Nitrite/Nitrate concentrations on Corrosivity of Washed Precipitate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Congdon, J.W.

2001-03-28

Cyclic polarization scans were performed using A-537 carbon steel in simulated washed precipitate solutions of various nitrite and nitrate concentrations. The results of this study indicate that nitrate is an aggressive anion in washed precipitate. Furthermore, a quantitative linear log-log relationship between the minimum effective nitrite concentration and the nitrate concentration was established for washed precipitate with other ions at their average compositions.

Drivers in the Scaling Between Precipitation and Cloud Radiative Impacts in Deep Convection

NASA Astrophysics Data System (ADS)

Rapp, A. D.; Sun, L.; Smalley, K.

2017-12-01

The coupling between changes in radiation and precipitation has been demonstrated by a number of studies and suggests an important link between cloud and precipitation processes for defining climate sensitivity. Precipitation and radiative fluxes from CloudSat/CALIPSO retrieval products are used to examine the relationship between precipitation and cloud radiative impacts through two dimensionless parameters. The surface radiative cooling impact, Rc, represents the ratio of the surface shortwave cloud radiative effect to latent heating (LH) from precipitation. The atmospheric radiative heating impact, Rh, represents the ratio of the atmospheric cloud radiative effect to LH from precipitation. Together, these parameters describe the relationship between precipitation processes and how efficiently clouds cools the surface or heats the atmosphere. Deep convective clouds are identified using the 2B-GEOPROF-LIDAR joint radar-lidar product and the cloud radiative impact parameters are calculated from the 2B-FLXHR-LIDAR fluxes and 2C-RAIN-PROFILE precipitation. Deep convective clouds will be sampled according to their dynamic and thermodynamic regimes to provide insights into the factors that control the scaling between precipitation and radiative impacts. Preliminary results from analysis of precipitating deep convective pixels indicates a strong increase (decrease) in the ratio of atmospheric heating (surface cooling) and precipitation with thermodynamic environment, especially increasing water vapor; however, it remains to be seen whether these results hold when integrated over an entire deep convective cloud system. Analysis of the dependence of Rc and Rh on the cloud horizontal and vertical structure is also planned, which should lead to a better understanding of the role of non-precipitating anvil characteristics in modulating the relationship between precipitation and surface and atmospheric radiative effects.

Genotype and plant trait effects on soil CO2 efflux responses to altered precipitation in switchgrass

USDA-ARS?s Scientific Manuscript database

Background/Question/Methods Global climate change models predict increasing drought during the growing season, which will alter many ecosystem processes including soil CO2 efflux (JCO2), with potential consequences for carbon retention in soils. Soil moisture, soil temperature and plant traits such...

Insult to Injury: Disability, Earnings, and Divorce

ERIC Educational Resources Information Center

Singleton, Perry

2012-01-01

This study measures the longitudinal effect of disability on earnings, marriage, and divorce. The data come from the Survey of Income and Program Participation matched to administrative data on longitudinal earnings. Using event-study methods, the results show that the onset of a work-preventing disability is associated with a precipitous decline…

Growth and physiological plasticity among differentially adapted genotypes of a widespread C4 grass under altered precipitation

USDA-ARS?s Scientific Manuscript database

Background/Question/Methods Variation in precipitation expected with climate change may impact plant fitness and alter ecosystem dynamics by modifying species phenology, productivity, and physiology. Species responses to varied precipitation will depend in part on plastic responses of genotypes ad...

Dynamical downscaling of regional climate over eastern China using RSM with multiple physics scheme ensembles

NASA Astrophysics Data System (ADS)

Peishu, Zong; Jianping, Tang; Shuyu, Wang; Lingyun, Xie; Jianwei, Yu; Yunqian, Zhu; Xiaorui, Niu; Chao, Li

2017-08-01

The parameterization of physical processes is one of the critical elements to properly simulate the regional climate over eastern China. It is essential to conduct detailed analyses on the effect of physical parameterization schemes on regional climate simulation, to provide more reliable regional climate change information. In this paper, we evaluate the 25-year (1983-2007) summer monsoon climate characteristics of precipitation and surface air temperature by using the regional spectral model (RSM) with different physical schemes. The ensemble results using the reliability ensemble averaging (REA) method are also assessed. The result shows that the RSM model has the capacity to reproduce the spatial patterns, the variations, and the temporal tendency of surface air temperature and precipitation over eastern China. And it tends to predict better climatology characteristics over the Yangtze River basin and the South China. The impact of different physical schemes on RSM simulations is also investigated. Generally, the CLD3 cloud water prediction scheme tends to produce larger precipitation because of its overestimation of the low-level moisture. The systematic biases derived from the KF2 cumulus scheme are larger than those from the RAS scheme. The scale-selective bias correction (SSBC) method improves the simulation of the temporal and spatial characteristics of surface air temperature and precipitation and advances the circulation simulation capacity. The REA ensemble results show significant improvement in simulating temperature and precipitation distribution, which have much higher correlation coefficient and lower root mean square error. The REA result of selected experiments is better than that of nonselected experiments, indicating the necessity of choosing better ensemble samples for ensemble.

Diabatic forcing and initialization with assimilation of cloud and rain water in a forecast model: Methodology

NASA Technical Reports Server (NTRS)

Raymond, William H.; Olson, William S.; Callan, Geary

1990-01-01

The focus of this part of the investigation is to find one or more general modeling techniques that will help reduce the time taken by numerical forecast models to initiate or spin-up precipitation processes and enhance storm intensity. If the conventional data base could explain the atmospheric mesoscale flow in detail, then much of our problem would be eliminated. But the data base is primarily synoptic scale, requiring that a solution must be sought either in nonconventional data, in methods to initialize mesoscale circulations, or in ways of retaining between forecasts the model generated mesoscale dynamics and precipitation fields. All three methods are investigated. The initialization and assimilation of explicit cloud and rainwater quantities computed from conservation equations in a mesoscale regional model are examined. The physical processes include condensation, evaporation, autoconversion, accretion, and the removal of rainwater by fallout. The question of how to initialize the explicit liquid water calculations in numerical models and how to retain information about precipitation processes during the 4-D assimilation cycle are important issues that are addressed. The explicit cloud calculations were purposely kept simple so that different initialization techniques can be easily and economically tested. Precipitation spin-up processes associated with three different types of weather phenomena are examined. Our findings show that diabatic initialization, or diabatic initialization in combination with a new diabatic forcing procedure, work effectively to enhance the spin-up of precipitation in a mesoscale numerical weather prediction forecast. Also, the retention of cloud and rain water during the analysis phase of the 4-D data assimilation procedure is shown to be valuable. Without detailed observations, the vertical placement of the diabatic heating remains a critical problem.

Processes for making dense, spherical active materials for lithium-ion cells

DOEpatents

Kang, Sun-Ho [Naperville, IL; Amine, Khalil [Downers Grove, IL

2011-11-22

Processes are provided for making dense, spherical mixed-metal carbonate or phosphate precursors that are particularly well suited for the production of active materials for electrochemical devices such as lithium ion secondary batteries. Exemplified methods include precipitating dense, spherical particles of metal carbonates or metal phosphates from a combined aqueous solution using a precipitating agent such as ammonium hydrogen carbonate, sodium hydrogen carbonate, or a mixture that includes sodium hydrogen carbonate. Other exemplified methods include precipitating dense, spherical particles of metal phosphates using a precipitating agent such as ammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, or a mixture of any two or more thereof. Further provided are compositions of and methods of making dense, spherical metal oxides and metal phosphates using the dense, spherical metal precursors. Still further provided are electrodes and batteries using the same.

Mineral Precipitation in Fractures: Multiscale Imaging and Geochemical Modeling

NASA Astrophysics Data System (ADS)

Hajirezaie, S.; Peters, C. A.; Swift, A.; Sheets, J. M.; Cole, D. R.; Crandall, D.; Cheshire, M.; Stack, A. G.; Anovitz, L. M.

2017-12-01

For subsurface energy technologies such as geologic carbon sequestration, fractures are potential pathways for fluid migration from target formations. Highly permeable fractures may become sealed by mineral precipitation. In this study, we examined shale specimens with existing cemented fractures as natural analogues, using an array of imaging methods to characterize mineralogy and porosity at several spatial scales. In addition, we used reactive transport modeling to investigate geochemical conditions that can lead to extensive mineral precipitation and to simulate the impacts on fracture hydraulic properties. The naturally-cemented fractured rock specimens were from the Upper Wolfcamp formation in Texas, at 10,000 ft depth. The specimens were scanned using x-ray computed tomography (xCT) at resolution of 13 microns. The xCT images revealed an original fracture aperture of 1.9 mm filled with several distinct mineral phases and vuggy void regions, and the mineral phase volumes and surface areas were quantified and mapped in 3D. Specimens were thin-sectioned and examined at micron- and submicron-scales using petrographic microscopy (PM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and small angle X-ray scattering (SAXS). Collectively these methods revealed crystals of dolomite as large as 900 microns in length overlain with a heterogeneous mixture of carbonate minerals including calcite, dolomite, and Fe-rich dolomite, interspersed at spatial scales as small as 5 microns. In addition, secondary precipitation of SiO2 was found to fill some of the void space. This multiscale imaging was used to inform the reactive transport modeling employed to examine the conditions that can cause the observed mineral precipitation in fractures at a larger scale. Two brines containing solutions that when mixed would lead to precipitation of various carbonate minerals were simulated as injectants into a fracture domain. In particular, the competing effects of transport dynamics and reaction kinetics were investigated in the context of profiles of the precipitated minerals and permeability behavior of the fracture flow path. This study contributes rich knowledge toward mastering the subsurface for energy production and storage and for the management of energy waste streams.

Joint distribution of temperature and precipitation in the Mediterranean, using the Copula method

NASA Astrophysics Data System (ADS)

Lazoglou, Georgia; Anagnostopoulou, Christina

2018-03-01

This study analyses the temperature and precipitation dependence among stations in the Mediterranean. The first station group is located in the eastern Mediterranean (EM) and includes two stations, Athens and Thessaloniki, while the western (WM) one includes Malaga and Barcelona. The data was organized in two time periods, the hot-dry period and the cold-wet one, composed of 5 months, respectively. The analysis is based on a new statistical technique in climatology: the Copula method. Firstly, the calculation of the Kendall tau correlation index showed that temperatures among stations are dependant during both time periods whereas precipitation presents dependency only between the stations located in EM or WM and only during the cold-wet period. Accordingly, the marginal distributions were calculated for each studied station, as they are further used by the copula method. Finally, several copula families, both Archimedean and Elliptical, were tested in order to choose the most appropriate one to model the relation of the studied data sets. Consequently, this study achieves to model the dependence of the main climate parameters (temperature and precipitation) with the Copula method. The Frank copula was identified as the best family to describe the joint distribution of temperature, for the majority of station groups. For precipitation, the best copula families are BB1 and Survival Gumbel. Using the probability distribution diagrams, the probability of a combination of temperature and precipitation values between stations is estimated.

MANGANESE DIOXIDE METHOD FOR PREPARATION OF PROTACTINIUM

DOEpatents

Katzin, L.I.

1958-08-12

A method of obtaining U/sup 233/ is described. An aqueous solution of neutriln irradiated thoriunn is treated by forming tberein a precipitate of manganese dioxide which carries and thus separates the Pa/sup 233/ from the solution. The carrier precipitate so formed is then dissolved in an acidic solution containing a reducing agent sufficiently electronegative to reduce the tetravalent manganese to the divalent state. Further purification of the Pa/sup 233/ may be obtained by forming another manganese dioxide carrier precipitate and subsequently dissolving it. Ater a sufficient number of such cycles have brought the Pa/sup 233/ to the desired purity, the solution is aged, allowing the formation ot U/sup 233/ by radioaetive decay. A manganese dioxide precipitate is then formed in the U/sup 233/ containing solution. This precipitate carries down any remaining Pa/sup 233/ thus leaving the separated U/sup 233/solution, from whieh it may be easily recovered.

CARBONATE METHOD OF SEPARATION OF TETRAVALENT PLUTONIUM FROM FISSION PRODUCT VALUES

DOEpatents

Duffield, R.B.; Stoughton, R.W.

1959-02-01

It has been found that plutonium forms an insoluble precipitate with carbonate ion when the carbonate ion is present in stoichiometric proportions, while an excess of the carbonate ion complexes plutonium and renders it soluble. A method for separating tetravalent plutonium from lanthanum-group rare earths has been based on this discovery, since these rare earths form insoluble carbonates in approximately neutral solutions. According to the process the pH is adjusted to between 5 and 7, and approximately stoichiometric amounts of carbonate ion are added to the solution causing the formation of a precipitate of plutonium carbonate and the lanthanum-group rare earth carbonates. The precipitate is then separated from the solution and contacted with a carbonate solution of a concentration between 1 M and 3 M to complex and redissolve the plutonium precipitate, and thus separate it from the insoluble rare earth precipitate.

Effect of Etching Methods in Metallographic Studies of Duplex Stainless Steel 2205

NASA Astrophysics Data System (ADS)

Kisasoz, A.; Karaaslan, A.; Bayrak, Y.

2017-03-01

Three different etching methods are used to uncover the ferrite-austenite structure and precipitates of secondary phases in stainless steel 22.5% Cr - 5.4% Ni - 3% Mo - 1.3% Mn. The structure is studied under a light microscope. The chemical etching is conducted in a glycerol solution of HNO3, HCl and HF; the electrochemical etching is conducted in solutions of KOH and NaOH.

On the formation and stability of nanometer scale precipitates in ferritic alloys during processing and high temperature service

NASA Astrophysics Data System (ADS)

Alinger, Matthew J.

Iron powders containing ≈14wt%Cr and smaller amounts of W and Ti were mechanically alloyed (MA) by ball milling with Y2O3 and subsequently either hot consolidated by hot extrusion or isostatic pressing, or powder annealed, producing very high densities of nm-scale coherent transition phase precipitates, or Y-Ti-O nano-clusters (NCs), along with fine-scale grains. These so-called nanostructured ferritic alloys (NFAs) manifest very high strength (static and creep) and corrosion-oxidation resistance up to temperatures in excess of 800°C. We used a carefully designed matrix of model MA powders and consolidated alloys to systematically assess the NC evolutions during each processing step, and to explore the combined effects of alloy composition and a number of processing variables, including the milling energy, consolidation method and the time and temperature of annealing of the as-milled powders. The stability of the NCs was also characterized during high-temperate post-consolidation annealing of a commercial NFA, MA957. The micro-nanostructural evolutions, and their effects on the alloy strength, were characterized by a combination of techniques, including XRD, TEM, atom-probe tomography (APT) and positron annihilation spectroscopy (PAS). However, small angle neutron scattering (SANS) was the primary tool used to characterize the nm-scale precipitates. The effect of the micro-nanostructure on the alloy strength was assessed by microhardness measurements. The studies revealed the critical sequence-of-events in forming the NCs, involves dissolution of Y, Ti and O during ball milling. The supersaturated solutes then precipitate during hot consolidation or powder annealing. The precipitate volume fraction increases with both the milling energy and Ti additions at lower consolidation and annealing temperatures (850°C), and at higher processing temperatures (1150°C) both are needed to produce NCs. The non-equilibrium kinetics of NC formation are nucleation controlled and independent of time with an effective activation energy of ≈60 kJ/mole. High temperature precipitate coarsening and transformations to oxide phases show a high effective activation energy (≈880 kJ/mole) and have a time dependence characteristic of a dislocation pipe diffusion mechanism. The NCs act as weak to moderately strong (alpha = 0.1 to 0.5) obstacles that can be sheared by dislocations, where the obstacle strength increases with alpha ≈0.37log(r/2b).

Structural, optical, magnetic and electrical properties of hematite (α-Fe2O3) nanoparticles synthesized by two methods: polyol and precipitation

NASA Astrophysics Data System (ADS)

Mansour, Houda; Letifi, Hanen; Bargougui, Radhouane; De Almeida-Didry, Sonia; Negulescu, Beatrice; Autret-Lambert, Cécile; Gadri, Abdellatif; Ammar, Salah

2017-12-01

Hematite (α-Fe2O3) nanoparticles have been successfully synthesized via two methods: (1) polyol and (2) precipitation in water. The influence of synthesis methods on the crystalline structure, morphological, optical, magnetic and electrical properties were investigated using X-ray diffraction, RAMAN spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-visible diffuse reflectance spectroscopy (UV-vis DRS), superconducting quantum interference device and impedance spectroscopy. The structural properties showed that the obtained hematite α-Fe2O3 nanoparticles with two preparation methods exhibit hexagonal phase with high crystallinity and high-phase stability at room temperature. It was found that the average hematite nanoparticle size is estimated to be 36.86 nm for the sample synthesized by precipitation and 54.14 nm for the sample synthesized by polyol. Moreover, the optical properties showed that the band gap energy value of α-Fe2O3 synthesized by precipitation (2.07 eV) was higher than that of α-Fe2O3 synthesized by polyol (1.97 eV) and they showed a red shift to the visible region. Furthermore, the measurements of magnetic properties indicated a magnetization loop typical of ferromagnetic systems at room temperature. Measurements of electrical properties show higher dielectric permittivity (5.64 × 103) and relaxation phenomenon for α-Fe2O3 issued from the precipitation method than the other sample.

Depletion of abundant plant RuBisCO protein using the protamine sulfate precipitation method.

PubMed

Kim, Yu Ji; Lee, Hye Min; Wang, Yiming; Wu, Jingni; Kim, Sang Gon; Kang, Kyu Young; Park, Ki Hun; Kim, Yong Chul; Choi, In Soo; Agrawal, Ganesh Kumar; Rakwal, Randeep; Kim, Sun Tae

2013-07-01

Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the most abundant plant leaf protein, hampering deep analysis of the leaf proteome. Here, we describe a novel protamine sulfate precipitation (PSP) method for the depletion of RuBisCO. For this purpose, soybean leaf total proteins were extracted using Tris-Mg/NP-40 extraction buffer. Obtained clear supernatant was subjected to the PSP method, followed by 13% SDS-PAGE analysis of total, PS-supernatant and -precipitation derived protein samples. In a dose-dependent experiment, 0.1% w/v PS was found to be sufficient for precipitating RuBisCO large and small subunits (LSU and SSU). Western blot analysis confirmed no detection of RuBisCO LSU in the PS-supernatant proteins. Application of this method to Arabidopsis, rice, and maize leaf proteins revealed results similar to soybean. Furthermore, 2DE analyses of PS-treated soybean leaf displayed enriched protein profile for the protein sample derived from the PS-supernatant than total proteins. Some enriched 2D spots were subjected to MALDI-TOF-TOF analysis and were successfully assigned for their protein identity. Hence, the PSP method is: (i) simple, fast, economical, and reproducible for RuBisCO precipitation from the plant leaf sample; (ii) applicable to both dicot and monocot plants; and (iii) suitable for downstream proteomics analysis. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Size-controlled fabrication of zein nano/microparticles by modified anti-solvent precipitation with/without sodium caseinate

PubMed Central

Li, Feng; Chen, Yan; Liu, Shubo; Qi, Jian; Wang, Weiying; Wang, Chenhua; Zhong, Ruiyue; Chen, Zhijun; Li, Xiaoming; Guan, Yuanzhou; Kong, Wei; Zhang, Yong

2017-01-01

Zein-based nano/microparticles have been demonstrated to be promising carrier systems for both the food industry and biomedical applications. However, the fabrication of size-controlled zein particles has been a challenging issue. In this study, a modified anti-solvent precipitation method was developed, and the effects of various factors, such as mixing method, solvent/anti-solvent ratio, temperature, zein concentrations and the presence of sodium caseinate (SC) on properties of zein particles were investigated. Evidence is presented that, among the previously mentioned factors, the mixing method, especially mixing rate, could be used as an effective parameter to control the size of zein particles without changing other parameters. Moreover, through fine-tuning the mixing rate together with zein concentration, particles with sizes ranging from nanometers to micrometers and low polydispersity index values could be easily obtained. Based on the size-controlled fabrication method, SC-coated zein nanoparticles could also be obtained in a size-controlled manner by incubation of the coating material with the already-formed zein particles. The resultant nanoparticles showed better performance in both drug loading and controlled release, compared with zein/SC hybrid nanoparticles fabricated by adding aqueous ethanol solution to SC solution. The possible mechanisms of the nanoprecipitation process and self-assembly formation of these nanoparticles are discussed. PMID:29184408

Size-controlled fabrication of zein nano/microparticles by modified anti-solvent precipitation with/without sodium caseinate.

PubMed

Li, Feng; Chen, Yan; Liu, Shubo; Qi, Jian; Wang, Weiying; Wang, Chenhua; Zhong, Ruiyue; Chen, Zhijun; Li, Xiaoming; Guan, Yuanzhou; Kong, Wei; Zhang, Yong

2017-01-01

Zein-based nano/microparticles have been demonstrated to be promising carrier systems for both the food industry and biomedical applications. However, the fabrication of size-controlled zein particles has been a challenging issue. In this study, a modified anti-solvent precipitation method was developed, and the effects of various factors, such as mixing method, solvent/anti-solvent ratio, temperature, zein concentrations and the presence of sodium caseinate (SC) on properties of zein particles were investigated. Evidence is presented that, among the previously mentioned factors, the mixing method, especially mixing rate, could be used as an effective parameter to control the size of zein particles without changing other parameters. Moreover, through fine-tuning the mixing rate together with zein concentration, particles with sizes ranging from nanometers to micrometers and low polydispersity index values could be easily obtained. Based on the size-controlled fabrication method, SC-coated zein nanoparticles could also be obtained in a size-controlled manner by incubation of the coating material with the already-formed zein particles. The resultant nanoparticles showed better performance in both drug loading and controlled release, compared with zein/SC hybrid nanoparticles fabricated by adding aqueous ethanol solution to SC solution. The possible mechanisms of the nanoprecipitation process and self-assembly formation of these nanoparticles are discussed.

Selective Precipitation and Purification of Monovalent Proteins Using Oligovalent Ligands and Ammonium Sulfate

PubMed Central

Mirica, Katherine A.; Lockett, Matthew R.; Snyder, Phillip W.; Shapiro, Nathan D.; Mack, Eric T.; Nam, Sarah; Whitesides, George M.

2012-01-01

This paper describes a method for the selective precipitation and purification of a monovalent protein (carbonic anhydrase is used as a demonstration) from cellular lysate using ammonium sulfate and oligovalent ligands. The oligovalent ligands induce the formation of protein-ligand aggregates, and at an appropriate concentration of dissolved ammonium sulfate, these complexes precipitate. The purification involves three steps: i) the removal of high-molecular weight impurities through the addition of ammonium sulfate to the crude cell lysate; ii) the introduction of an oligovalent ligand and the selective precipitation of the target protein-ligand aggregates from solution; and iii) the removal of the oligovalent ligand from the precipitate by dialysis to release the target protein. The increase of mass and volume of the proteins upon aggregate formation reduces their solubility, and results in the selective precipitation of these aggregates. We recovered human carbonic anhydrase, from crude cellular lysate, in 82% yield and 95% purity with a trivalent benzene sulfonamide ligand. This method provides a chromatography-free strategy of purifying monovalent proteins—for which appropriate oligovalent ligands can be synthesized—and combines the selectivity of affinity-based purification with the convenience of salt-induced precipitation. PMID:22188202

Selective precipitation and purification of monovalent proteins using oligovalent ligands and ammonium sulfate.

PubMed

Mirica, Katherine A; Lockett, Matthew R; Snyder, Phillip W; Shapiro, Nathan D; Mack, Eric T; Nam, Sarah; Whitesides, George M

2012-02-15

This paper describes a method for the selective precipitation and purification of a monovalent protein (carbonic anhydrase is used as a demonstration) from cellular lysate using ammonium sulfate and oligovalent ligands. The oligovalent ligands induce the formation of protein-ligand aggregates, and at an appropriate concentration of dissolved ammonium sulfate, these complexes precipitate. The purification involves three steps: (i) the removal of high-molecular-weight impurities through the addition of ammonium sulfate to the crude cell lysate; (ii) the introduction of an oligovalent ligand and the selective precipitation of the target protein-ligand aggregates from solution; and (iii) the removal of the oligovalent ligand from the precipitate by dialysis to release the target protein. The increase of mass and volume of the proteins upon aggregate formation reduces their solubility, and results in the selective precipitation of these aggregates. We recovered human carbonic anhydrase, from crude cellular lysate, in 82% yield and 95% purity with a trivalent benzene sulfonamide ligand. This method provides a chromatography-free strategy of purifying monovalent proteins--for which appropriate oligovalent ligands can be synthesized--and combines the selectivity of affinity-based purification with the convenience of salt-induced precipitation.

Determining the composition of small features in atom probe: bcc Cu-rich precipitates in an Fe-rich matrix.

PubMed

Morley, A; Sha, G; Hirosawa, S; Cerezo, A; Smith, G D W

2009-04-01

Aberrations in the ion trajectories near the specimen surface are an important factor in the spatial resolution of the atom probe technique. Near the boundary between two phases with dissimilar evaporation fields, ion trajectory overlaps may occur, leading to a biased measurement of composition in the vicinity of this interface. In the case of very small second-phase precipitates, the region affected by trajectory overlaps may extend to the centre of the precipitate prohibiting a direct measurement of composition. A method of quantifying the aberrant matrix contribution and thus estimating the underlying composition is presented. This method is applied to the Fe-Cu-alloy system, where the precipitation of low-nanometre size Cu-rich precipitates is of considerable technical importance in a number of materials applications. It is shown definitively that there is a non-zero underlying level of Fe within precipitates formed upon thermal ageing, which is augmented and masked by trajectory overlaps. The concentration of Fe in the precipitate phase is shown to be a function of ageing temperature. An estimate of the underlying Fe level is made, which is at lower levels than commonly reported by atom probe investigations.

To Which Extent can Aerosols Affect Alpine Mixed-Phase Clouds?

NASA Astrophysics Data System (ADS)

Henneberg, O.; Lohmann, U.

2017-12-01

Aerosol-cloud interactions constitute a high uncertainty in regional climate and changing weather patterns. Such uncertainties are due to the multiple processes that can be triggered by aerosol especially in mixed-phase clouds. Mixed-phase clouds most likely result in precipitation due to the formation of ice crystals, which can grow to precipitation size. Ice nucleating particles (INPs) determine how fast these clouds glaciate and form precipitation. The potential for INP to transfer supercooled liquid clouds to precipitating clouds depends on the available humidity and supercooled liquid. Those conditions are determined by dynamics. Moderately high updraft velocities result in persistent mixed-phase clouds in the Swiss Alps [1], which provide an ideal testbed to investigate the effect of aerosol on precipitation in mixed-phase clouds. To address the effect of aerosols in orographic winter clouds under different dynamic conditions, we run a number of real case ensembles with the regional climate model COSMO on a horizontal resolution of 1.1 km. Simulations with different INP concentrations within the range observed at the GAW research station Jungfraujoch in the Swiss Alps are conducted and repeated within the ensemble. Microphysical processes are described with a two-moment scheme. Enhanced INP concentrations enhance the precipitation rate of a single precipitation event up to 20%. Other precipitation events of similar strength are less affected by the INP concentration. The effect of CCNs is negligible for precipitation from orographic winter clouds in our case study. There is evidence for INP to change precipitation rate and location more effectively in stronger dynamic regimes due to the enhanced potential to transfer supercooled liquid to ice. The classification of the ensemble members according to their dynamics will quantify the interaction of aerosol effects and dynamics. Reference [1] Lohmann et al, 2016: Persistence of orographic mixed-phase clouds, GRL

Bioactive Polymeric Nanoparticles for Periodontal Therapy

PubMed Central

Alfonso-Rodríguez, Camilo Andrés; Medina-Castillo, Antonio L.; Alaminos, Miguel; Toledano, Manuel

2016-01-01

Aims to design calcium and zinc-loaded bioactive and cytocompatible nanoparticles for the treatment of periodontal disease. Methods PolymP-nActive nanoparticles were zinc or calcium loaded. Biomimetic calcium phosphate precipitation on polymeric particles was assessed after 7 days immersion in simulated body fluid, by scanning electron microscopy attached to an energy dispersive analysis system. Amorphous mineral deposition was probed by X-ray diffraction. Cell viability analysis was performed using oral mucosa fibroblasts by: 1) quantifying the liberated deoxyribonucleic acid from dead cells, 2) detecting the amount of lactate dehydrogenase enzyme released by cells with damaged membranes, and 3) by examining the cytoplasmic esterase function and cell membranes integrity with a fluorescence-based method using the Live/Dead commercial kit. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests. Results Precipitation of calcium and phosphate on the nanoparticles surfaces was observed in calcium-loaded nanoparticles. Non-loaded nanoparticles were found to be non-toxic in all the assays, calcium and zinc-loaded particles presented a dose dependent but very low cytotoxic effect. Conclusions The ability of calcium-loaded nanoparticles to promote precipitation of calcium phosphate deposits, together with their observed non-toxicity may offer new strategies for periodontal disease treatment. PMID:27820866

Application Of Empirical Phase Diagrams For Multidimensional Data Visualization Of High Throughput Microbatch Crystallization Experiments.

PubMed

Klijn, Marieke E; Hubbuch, Jürgen

2018-04-27

Protein phase diagrams are a tool to investigate cause and consequence of solution conditions on protein phase behavior. The effects are scored according to aggregation morphologies such as crystals or amorphous precipitates. Solution conditions affect morphological features, such as crystal size, as well as kinetic features, such as crystal growth time. Common used data visualization techniques include individual line graphs or symbols-based phase diagrams. These techniques have limitations in terms of handling large datasets, comprehensiveness or completeness. To eliminate these limitations, morphological and kinetic features obtained from crystallization images generated with high throughput microbatch experiments have been visualized with radar charts in combination with the empirical phase diagram (EPD) method. Morphological features (crystal size, shape, and number, as well as precipitate size) and kinetic features (crystal and precipitate onset and growth time) are extracted for 768 solutions with varying chicken egg white lysozyme concentration, salt type, ionic strength and pH. Image-based aggregation morphology and kinetic features were compiled into a single and easily interpretable figure, thereby showing that the EPD method can support high throughput crystallization experiments in its data amount as well as its data complexity. Copyright © 2018. Published by Elsevier Inc.

Impact of Aerosols on Convective Clouds and Precipitation

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Chen, Jen-Ping; Li, Zhanqing; Wang, Chien; Zhang, Chidong

2011-01-01

Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major reason for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosol effects on clouds could further extend to precipitation, both through the formation of cloud particles and by exerting persistent radiative forcing on the climate system that disturbs dynamics. However, the various mechanisms behind these effects, in particular the ones connected to precipitation, are not yet well understood. The atmospheric and climate communities have long been working to gain a better grasp of these critical effects and hence to reduce the significant uncertainties in climate prediction resulting from such a lack of adequate knowledge. The central theme of this paper is to review past efforts and summarize our current understanding of the effect of aerosols on precipitation processes from theoretical analysis of microphysics, observational evidence, and a range of numerical model simulations. In addition, the discrepancy between results simulated by models, as well as that between simulations and observations will be presented. Specifically, this paper will address the following topics: (1) fundamental theories of aerosol effects on microphysics and precipitation processes, (2) observational evidence of the effect of aerosols on precipitation processes, (3) signatures of the aerosol impact on precipitation from large-scale analyses, (4) results from cloud-resolving model simulations, and (5) results from large-scale numerical model simulations. Finally, several future research directions on aerosol - precipitation interactions are suggested.

Impact of Aerosols on Convective Clouds and Precipitation

NASA Technical Reports Server (NTRS)

Tao, Wei-Kuo; Chen, Jen-Ping; Li, Zhanqing; Wang, Chien; Zhang, Chidong

2012-01-01

Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosol effects on clouds could further extend to precipitation, both through the formation of cloud particles and by exerting persistent radiative forcing on the climate system that disturbs dynamics. However, the various mechanisms behind these effects, in particular the ones connected to precipitation, are not yet well understood. The atmospheric and climate communities have long been working to gain a better grasp of these critical effects and hence to reduce the significant uncertainties in climate prediction resulting from such a lack of adequate knowledge. Here we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes from theoretical analysis of microphysics, observational evidence, and a range of numerical model simulations. In addition, the discrepancy between results simulated by models, as well as that between simulations and observations, are presented. Specifically, this paper addresses the following topics: (1) fundamental theories of aerosol effects on microphysics and precipitation processes, (2) observational evidence of the effect of aerosols on precipitation processes, (3) signatures of the aerosol impact on precipitation from largescale analyses, (4) results from cloud-resolving model simulations, and (5) results from large-scale numerical model simulations. Finally, several future research directions for gaining a better understanding of aerosol--cloud-precipitation interactions are suggested.

SeaWinds Scatterometer Wind Vector Retrievals Within Hurricanes Using AMSR and NEXRAD to Perform Corrections for Precipitation Effects: Comparison of AMSR and NEXRAD Retrievals of Rain

NASA Technical Reports Server (NTRS)

Weissman, David E.; Hristova-Veleva, Svetla; Callahan, Philip

2006-01-01

The opportunity provided by satellite scatterometers to measure ocean surface winds in strong storms and hurricanes is diminished by the errors in the received backscatter (SIGMA-0) caused by the attenuation, scattering and surface roughening produced by heavy rain. Providing a good rain correction is a very challenging problem, particularly at Ku band (13.4 GHz) where rain effects are strong. Corrections to the scatterometer measurements of ocean surface winds can be pursued with either of two different methods: empirical or physical modeling. The latter method is employed in this study because of the availability of near simultaneous and collocated measurements provided by the MIDORI-II suite of instruments. The AMSR was designed to measure atmospheric water-related parameters on a spatial scale comparable to the SeaWinds scatterometer. These quantities can be converted into volumetric attenuation and scattering at the Ku-band frequency of SeaWinds. Optimal estimates of the volume backscatter and attenuation require a knowledge of the three dimensional distribution of reflectivity on a scale comparable to that of the precipitation. Studies selected near the US coastline enable the much higher resolution NEXRAD reflectivity measurements evaluate the AMSR estimates. We are also conducting research into the effects of different beam geometries and nonuniform beamfilling of precipitation within the field-of-view of the AMSR and the scatterometer. Furthermore, both AMSR and NEXRAD estimates of atmospheric correction can be used to produce corrected SIGMA-0s, which are then input to the JPL wind retrieval algorithm.

Duplex precipitates and their effects on the room-temperature fracture behaviour of a NiAl-strengthened ferritic alloy

DOE PAGES

Sun, Zhiqian; Song, Gian; Ilavsky, Jan; ...

2015-03-23

Duplex precipitates are presented in a NiAl-strengthened ferritic alloy. They were characterized by the ultra-small angle X-ray scattering and transmission electron microscope. Fine cooling precipitates with the size of several to tens of nanometres harden the matrix considerably at room temperature. The cracks will likely to initiate from precipitates, and coalesce and propagate quickly through the matrix due to the excessive hardening effect of cooling precipitates, which lead to the premature fracture of NiAl-strengthened ferritic alloys.

Applying complex networks to evaluate precipitation patterns over South America

NASA Astrophysics Data System (ADS)

Ciemer, Catrin; Boers, Niklas; Barbosa, Henrique; Kurths, Jürgen; Rammig, Anja

2016-04-01

The climate of South America exhibits pronounced differences between the wet- and the dry-season, which are accompanied by specific synoptic events like changes in the location of the South American Low Level Jet (SALLJ) and the establishment of the South American Convergence Zone (SACZ). The onset of these events can be related to the presence of typical large-scale precipitation patterns over South America, as previous studies have shown[1,2]. The application of complex network methods to precipitation data recently received increased scientific attention for the special case of extreme events, as it is possible with such methods to analyze the spatiotemporal correlation structure as well as possible teleconnections of these events[3,4]. In these approaches the correlation between precipitation datasets is calculated by means of Event Synchronization which restricts their applicability to extreme precipitation events. In this work, we propose a method which is able to consider not only extreme precipitation but complete time series. A direct application of standard similarity measures in order to correlate precipitation time series is impossible due to their intricate statistical properties as the large amount of zeros. Therefore, we introduced and evaluated a suitable modification of Pearson's correlation coefficient to construct spatial correlation networks of precipitation. By analyzing the characteristics of spatial correlation networks constructed on the basis of this new measure, we are able to determine coherent areas of similar precipitation patterns, spot teleconnections of correlated areas, and detect central regions for precipitation correlation. By analyzing the change of the network over the year[5], we are also able to determine local and global changes in precipitation correlation patterns. Additionally, global network characteristics as the network connectivity yield indications for beginning and end of wet- and dry season. In order to identify large-scale synoptic events like the SACZ and SALLJ onset, detecting the changes of correlation over time between certain regions is of significant relevance. [1] Nieto-Ferreira et al. Quarterly Journal of the Royal Meteorological Society (2011) [2] Vera et al. Bulletin of the American Meteorological Society (2006) [3] Quiroga et al. Physical review E (2002) [4] Boers et al. nature communications (2014) [5] Radebach et al. Physical review E (2013)

On the importance of appropriate precipitation gauge catch correction for hydrological modelling at mid to high latitudes

NASA Astrophysics Data System (ADS)

Stisen, S.; Højberg, A. L.; Troldborg, L.; Refsgaard, J. C.; Christensen, B. S. B.; Olsen, M.; Henriksen, H. J.

2012-11-01

Precipitation gauge catch correction is often given very little attention in hydrological modelling compared to model parameter calibration. This is critical because significant precipitation biases often make the calibration exercise pointless, especially when supposedly physically-based models are in play. This study addresses the general importance of appropriate precipitation catch correction through a detailed modelling exercise. An existing precipitation gauge catch correction method addressing solid and liquid precipitation is applied, both as national mean monthly correction factors based on a historic 30 yr record and as gridded daily correction factors based on local daily observations of wind speed and temperature. The two methods, named the historic mean monthly (HMM) and the time-space variable (TSV) correction, resulted in different winter precipitation rates for the period 1990-2010. The resulting precipitation datasets were evaluated through the comprehensive Danish National Water Resources model (DK-Model), revealing major differences in both model performance and optimised model parameter sets. Simulated stream discharge is improved significantly when introducing the TSV correction, whereas the simulated hydraulic heads and multi-annual water balances performed similarly due to recalibration adjusting model parameters to compensate for input biases. The resulting optimised model parameters are much more physically plausible for the model based on the TSV correction of precipitation. A proxy-basin test where calibrated DK-Model parameters were transferred to another region without site specific calibration showed better performance for parameter values based on the TSV correction. Similarly, the performances of the TSV correction method were superior when considering two single years with a much dryer and a much wetter winter, respectively, as compared to the winters in the calibration period (differential split-sample tests). We conclude that TSV precipitation correction should be carried out for studies requiring a sound dynamic description of hydrological processes, and it is of particular importance when using hydrological models to make predictions for future climates when the snow/rain composition will differ from the past climate. This conclusion is expected to be applicable for mid to high latitudes, especially in coastal climates where winter precipitation types (solid/liquid) fluctuate significantly, causing climatological mean correction factors to be inadequate.

0.1 Trend analysis of δ18O composition of precipitation in Germany: Combining Mann-Kendall trend test and ARIMA models to correct for higher order serial correlation

NASA Astrophysics Data System (ADS)

Klaus, Julian; Pan Chun, Kwok; Stumpp, Christine

2015-04-01

Spatio-temporal dynamics of stable oxygen (18O) and hydrogen (2H) isotopes in precipitation can be used as proxies for changing hydro-meteorological and regional and global climate patterns. While spatial patterns and distributions gained much attention in recent years the temporal trends in stable isotope time series are rarely investigated and our understanding of them is still limited. These might be a result of a lack of proper trend detection tools and effort for exploring trend processes. Here we make use of an extensive data set of stable isotope in German precipitation. In this study we investigate temporal trends of δ18O in precipitation at 17 observation station in Germany between 1978 and 2009. For that we test different approaches for proper trend detection, accounting for first and higher order serial correlation. We test if significant trends in the isotope time series based on different models can be observed. We apply the Mann-Kendall trend tests on the isotope series, using general multiplicative seasonal autoregressive integrate moving average (ARIMA) models which account for first and higher order serial correlations. With the approach we can also account for the effects of temperature, precipitation amount on the trend. Further we investigate the role of geographic parameters on isotope trends. To benchmark our proposed approach, the ARIMA results are compared to a trend-free prewhiting (TFPW) procedure, the state of the art method for removing the first order autocorrelation in environmental trend studies. Moreover, we explore whether higher order serial correlations in isotope series affects our trend results. The results show that three out of the 17 stations have significant changes when higher order autocorrelation are adjusted, and four stations show a significant trend when temperature and precipitation effects are considered. Significant trends in the isotope time series are generally observed at low elevation stations (≤315 m a.s.l.). Higher order autoregressive processes are important in the isotope time series analysis. Our results show that the widely used trend analysis with only the first order autocorrelation adjustment may not adequately take account of the high order autocorrelated processes in the stable isotope series. The investigated time series analysis method including higher autocorrelation and external climate variable adjustments is shown to be a better alternative.

Modification of nanostructured calcium carbonate for efficient gene delivery.

PubMed

Zhao, Dong; Wang, Chao-Qun; Zhuo, Ren-Xi; Cheng, Si-Xue

2014-06-01

In this study, a facile method to modify nanostructured calcium carbonate (CaCO3) gene delivery systems by adding calcium phosphate (CaP) component was developed. CaCO3/CaP/DNA nanoparticles were prepared by the co-precipitation of Ca(2+) ions with plasmid DNA in the presence of carbonate and phosphate ions. For comparison, CaCO3/DNA nanoparticles and CaP/DNA co-precipitates were also prepared. The effects of carbonate ion/phosphate ion (CO3(2-)/PO4(3-)) ratio on the particle size and gene delivery efficiency were investigated. With an appropriate CO3(2-)/PO4(3-) ratio, the co-existence of carbonate and phosphate ions could control the size of co-precipitates effectively, and CaCO3/CaP/DNA nanoparticles with a decreased size and improved stability could be obtained. The in vitro gene transfections mediated by different nanoparticles in 293T cells and HeLa cells were carried out, using pGL3-Luc as a reporter plasmid. The gene transfection efficiency of CaCO3/CaP/DNA nanoparticles could be significantly improved as compared with CaCO3/DNA nanoparticles and CaP/DNA co-precipitates. The confocal microscopy study indicated that the cellular uptake and nuclear localization of CaCO3/CaP/DNA nanoparticles were significantly enhanced as compared with unmodified CaCO3/DNA nanoparticles. Copyright © 2014 Elsevier B.V. All rights reserved.

Outdoor temperature, precipitation, and wind speed affect physical activity levels in children: a longitudinal cohort study

PubMed Central

Edwards, Nicholas M.; Myer, Gregory D.; Kalkwarf, Heidi J.; Woo, Jessica G.; Khoury, Philip R.; Hewett, Timothy E.; Daniels, Stephen R.

2015-01-01

Objective Evaluate effects of local weather conditions on physical activity in early childhood. Methods Longitudinal prospective cohort study of 372 children, 3 years old at enrollment, drawn from a major US metropolitan community. Accelerometer-measured (RT3) physical activity was collected every 4 months over 5 years and matched with daily weather measures: day length, heating/cooling degrees (degrees mean temperature < 65°F or ≥ 65°F, respectively), wind, and precipitation. Mixed regression analyses, adjusted for repeated measures, were used to test the relationship between weather and physical activity. Results Precipitation and wind speed were negatively associated with total physical activity and moderate-vigorous physical activity (P<0.0001). Heating and cooling degrees were negatively associated with total physical activity and moderate-vigorous physical activity and positively associated with inactivity (all P<0.0001), independent of age, sex, race, BMI, day length, wind, and precipitation. For every 10 additional heating degrees there was a five-minute daily reduction in moderate-vigorous physical activity. For every additional 10 cooling degrees there was a 17-minute reduction in moderate-vigorous physical activity. Conclusions Inclement weather (higher/lower temperature, greater wind speed, more rain/snow) is associated with less physical activity in young children. These deleterious effects should be considered when planning physical activity research, interventions, and policies. PMID:25423667

Aerosol radiative effects on mesoscale cloud-precipitation variables over Northeast Asia during the MAPS-Seoul 2015 campaign

NASA Astrophysics Data System (ADS)

Park, Shin-Young; Lee, Hyo-Jung; Kang, Jeong-Eon; Lee, Taehyoung; Kim, Cheol-Hee

2018-01-01

The online model, Weather Research and Forecasting Model with Chemistry (WRF-Chem) is employed to interpret the effects of aerosol-cloud-precipitation interaction on mesoscale meteorological fields over Northeast Asia during the Megacity Air Pollution Study-Seoul (MAPS-Seoul) 2015 campaign. The MAPS-Seoul campaign is a pre-campaign of the Korea-United States Air Quality (KORUS-AQ) campaign conducted over the Korean Peninsula. We validated the WRF-Chem simulations during the campaign period, and analyzed aerosol-warm cloud interactions by diagnosing both aerosol direct, indirect, and total effects. The results demonstrated that aerosol directly decreased downward shortwave radiation up to -44% (-282 W m-2) for this period and subsequently increased downward longwave radiation up to +15% (∼52 W m-2) in the presence of low-level clouds along the thematic area. Aerosol increased cloud fraction indirectly up to ∼24% with the increases of both liquid water path and the droplet number mixing ratio. Precipitation properties were altered both directly and indirectly. Direct effects simply changed cloud-precipitation quantities via simple updraft process associated with perturbed radiation and temperature, while indirect effects mainly suppressed precipitation, but sometimes increased precipitation in the higher relative humidity atmosphere or near vapor-saturated condition. The total aerosol effects caused a time lag of the precipitation rate with the delayed onset time of up to 9 h. This implies the importance of aerosol effects in improving mesoscale precipitation rate prediction in the online approach in the presence of non-linear warm cloud.

A Comparison of Multisensor Precipitation Estimation Methods in Complex Terrain for Flash Flood Warning and Mitigation

NASA Astrophysics Data System (ADS)

Cifelli, R.; Chen, H.; Chandrasekar, C. V.; Willie, D.; Reynolds, D.; Campbell, C.; Zhang, Y.; Sukovich, E.

2012-12-01

Investigating the uncertainties and improving the accuracy of quantitative precipitation estimation (QPE) is a critical mission of the National Oceanic and Atmospheric Administration (NOAA). QPE is extremely challenging in regions of complex terrain like the western U.S. because of the sparse coverage of ground-based radar, complex orographic precipitation processes, and the effects of beam blockages (e.g., Westrick et al. 1999). In addition, the rain gauge density in complex terrain is often inadequate to capture spatial variability in the precipitation patterns. The NOAA Hydrometeorology Testbed (HMT) conducts research on precipitation and weather conditions that can lead to flooding, and fosters transition of scientific advances and new tools into forecasting operations (see hmt.noaa.gov). The HMT program consists of a series of demonstration projects in different geographical regions to enhance understanding of region specific processes related to precipitation, including QPE. There are a number of QPE systems that are widely used across NOAA for precipitation estimation (e.g., Cifelli et al. 2011; Chandrasekar et al. 2012). Two of these systems have been installed at the NOAA Earth System Research Laboratory: Multisensor Precipitation Estimator (MPE) and National Mosaic and Multi-sensor QPE (NMQ) developed by NWS and NSSL, respectively. Both provide gridded QPE products that include radar-only, gauge-only and gauge-radar-merged, etc; however, these systems often provide large differences in QPE (in terms of amounts and spatial patterns) due to differences in Z-R selection, vertical profile of reflectivity correction, and gauge interpolation procedures. Determining the appropriate QPE product and quantification of QPE uncertainty is critical for operational applications, including water management decisions and flood warnings. For example, hourly QPE is used to correct radar based rain rates used by the Flash Flood Monitoring and Prediction (FFMP) package in the NWS forecast offices for issuance of flash flood warnings. This study will evaluate the performance of MPE and NMQ QPE products using independent gauges, object identification techniques for spatial verification and impact on surface runoff using a distributed hydrologic model. The effort will consist of baseline evaluations of these QPE systems to determine which combination of algorithm features is appropriate as well as investigate new methods for combining the gage and radar data. The Russian River Basin in California is used to demonstrate the comparison methodology with data collected from several rainfall events in March 2012.

Precipitation and ultimate pH effect on chemical and gelation properties of protein prepared by isoelectric solubilization/precipitation process from pale, soft, exudative (PSE)-like chicken breast meat1.

PubMed

Zhao, X; Xing, T; Chen, X; Han, M-Y; Li, X; Xu, X-L; Zhou, G-H

2017-05-01

Pale, soft, exudative (PSE)-like chicken breast is considered deteriorated raw material in the poultry meat industry that has inferior processing ability. The chemical and gelation properties of PSE-like chicken breast meat paste were studied. These pastes were prepared by the pH adjustment method and protein isolation using the isoelectric solubilization/precipitation (ISP) process from PSE-like chicken meat. The ISP-isolated samples were solubilized at pH 11.0 and recovered at pH 5.5 and 6.2. The ultimate pH of the ISP-isolated protein and meat paste was adjusted to 6.2 and 7.0. The ultimate pH in this article referred to the final pH of the extracted protein and meat paste. Higher reactive sulfhydryl content and surface hydrophobicity were found in the precipitation at pH 6.2 than at pH 5.5. However, various ultimate pH values showed no significant influence on the surface hydrophobicity. The hardness of gel, as measured by textural profile analysis, was improved using 6.2 as the precipitation pH compared with pH 5.5. The viscoelastic modulus (G΄) of gel pastes prior to the thermal gelation was higher with ISP treatment. However, lower G΄ was seen after thermal gelation compared with the control. Dynamic rheological measurement demonstrated a different gel-forming mechanism for protein precipitated at pH values of 5.5 and 6.2 compared with the meat paste. The cooking loss showed that the recovered protein failed to form a gel with good water-retention capacity unless the ultimate pH was adjusted to 7.0. Gels made from protein extracted by the ISP method had higher yellowness and lower redness values, probably due to protein denaturation. Precipitation at pH 6.2 formed a harder gel with lower water-retention ability than that at pH 5.5, and this result was possibly due to higher surface hydrophobicity and S-S bridge formation. Overall, network characteristics of ISP-treated protein gels were strongly dependent on precipitation pH and ultimate pH. © 2016 Poultry Science Association Inc.

Effect of pre-strain on precipitation and exfoliation corrosion resistance in an Al-Zn-Mg alloy

NASA Astrophysics Data System (ADS)

Lu, Xianghan; Du, Zhiwei; Han, Xiaolei; Li, Ting; Wang, Guojun; Lu, Liying; Bai, Xiaoxia; Zhou, Tietao

2017-12-01

To investigate the effect of pre-strain on behaviors in a specially developed Al-4.5Zn-1.2Mg alloy, transmission electron microscopy (TEM) bright field (BF) imaging combined with select area electron diffraction (SAED), Vickers-hardness tests and electrical conductivity tests was conducted for insight into precipitation in aluminum (Al) matrix during two step ageing, and standard exfoliation corrosion (EXCO) test combined with high-angle angular dark field scanning transmission electron microscopy (HAADF-STEM) and scanning electron microscopy (SEM) was carried out for corrosion behavior. Results showed that pre-strain accelerated precipitation during two step ageing as the sequence of: (i) supersaturated solid solution (SSS), GPI zones precipitations, GPI dissolution; (ii) SSS, fcc precipitates, η’ phases or η phases. And the precipitation hardening of the fcc precipitates was not effective as GPI zones. Pre-strain also accelerated EXCO developing, which was mainly attributed to the coverage ratio of η phases on high-angle grain boundaries (HAGBs) increasing as pre-strain increase.

Large-Scale Covariability Between Aerosol and Precipitation Over the 7-SEAS Region: Observations and Simulations

NASA Technical Reports Server (NTRS)

Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Zhang, Chidong; Jeong, Myeong Jae; Gautam, Ritesh; Bettenhausen, Corey; Sayer, Andrew M.; Hansell, Richard A.; Liu, Xiaohong;

[Isolation and purification of seven catechin compounds from fresh tea leaves by semi-preparative liquid chromatography].

PubMed

Gong, Zhihong; Chen, Si; Gao, Jiangtao; Li, Meihong; Wang, Xiaxia; Lin, Jun; Yu, Xiaomin

2017-11-08

An effective and simple method was established to simultaneously purify seven tea catechins (gallocatechin (GC), epigallocatechin (EGC), catechin (C), epigallocatechin-3- O -gallate (EGCG), epicatechin (EC), epigallocatechin-3- O -(3- O -methyl)-gallate (EGCG3"Me) and epicatechin-3- O -gallate (ECG)) from fresh tea leaves by semi-preparative high performance liquid chromatography (HPLC). Fresh leaves of Tieguanyin tea were successively extracted with methanol and chloroform. Then crude catechins were precipitated from the aqueous fraction of chloroform extraction by adding lead subacetate. Crude catechins were used for the isolation of the seven target catechin compounds by semi-preparative HPLC. Methanol-water and acetonitrile-water were sequentially used as mobile phases. After two rounds of semi-preparative HPLC, all target compounds were achieved with high purities (>90%). The proposed method was tested on two additional tea cultivars and showed similar results. This method demonstrated a simple and efficient strategy based on solvent extraction, ion precipitation and semi-preparative HPLC for the preparation of multiple catechins from tea leaves.

A novel combined electrochemical-magnetic method for water treatment.

PubMed

Ibanez, Jorge G; Vazquez-Olavarrieta, Jorge Luis; Hernandez-Rivera, Lydia; Garcia-Sanchez, Martin Adolfo; Garcia-Pintor, Elizabeth

2012-01-01

Electrocoagulation (EC) is a wastewater treatment process in which aqueous pollutants can be removed by adsorption, entrapment, precipitation or coalescence during a coagulation step produced by electrochemically generated metallic species. When using Fe as the sacrificial electrode, Fe(2+) and Fe(3+) ions are formed. As Fe(3+) species are paramagnetic, this property can in principle be used to facilitate their removal through the application of a magnetic field. In the present work we present a proof-of-concept for a combined electrochemical-magnetic method for pollutant removal. For this approach, the amounts of Fe(2+) and Fe(3+) produced in an EC cell at various voltages were measured by spectroscopic methods to confirm that Fe(3+) species predominate (up to 84%). The effectiveness of the presence of a magnetic field in the precipitation of coagulants from a suspension was confirmed by monitoring the turbidity change versus time with and without exposure to a magnetic field, up to a 30% improvement.

Effects of the Physical Characteristics of Cerium Oxide on Plasma-Enhanced Tetraethylorthosiliate Removal Rate of Chemical Mechanical Polishing for Shallow Trench Isolation

NASA Astrophysics Data System (ADS)

Kim, Sang-Kyun; Paik, Ungyu; Oh, Seong-Geun; Park, Yong-Kook; Katoh, Takeo; Park, Jea-Gun

2003-03-01

Ceria powders were synthesized by two different methods, solid-state displacement reaction and wet chemical precipitation, and the influence of the physical characteristics of cerium oxide on the removal rate of plasma-enhanced tetraethylorthosilicate (PETEOS) and chemical vapor deposition (CVD) nitride films in chemical mechanical planarization (CMP) was investigated. The fundamental physicochemical property and electrokinetic behavior of ceria particles in aqueous suspending media were investigated to identify the correlation between the colloidal property of ceria and the CMP performance. The surface potentials of two different ceria particles are found to have different isoelectric point (pHiep) values and differences in physical properties of ceria particles such as porosity and density were found to be the key parameters in CMP of PETEOS films. Ceria powders synthesized by the solid-state displacement reaction method yielded a higher removal rate of PETEOS and higher selectivity than powders synthesized by the wet chemical precipitation method.

A perturbation approach for assessing trends in precipitation extremes across Iran

NASA Astrophysics Data System (ADS)

Tabari, Hossein; AghaKouchak, Amir; Willems, Patrick

2014-11-01

Extreme precipitation events have attracted a great deal of attention among the scientific community because of their devastating consequences on human livelihood and socio-economic development. To assess changes in precipitation extremes in a given region, it is essential to analyze decadal oscillations in precipitation extremes. This study examines temporal oscillations in precipitation data in several sub-regions of Iran using a novel quantile perturbation method during 1980-2010. Precipitation data from NASA's Modern-Era Retrospective Analysis for Research and Applications-Land (MERRA-Land) are used in this study. The results indicate significant anomalies in precipitation extremes in the northwest and southeast regions of Iran. Analysis of extreme precipitation perturbations reveals that perturbations for the monthly aggregation level are generally lower than the annual perturbations. Furthermore, high-oscillation and low-oscillation periods are found in extreme precipitation quantiles across different seasons. In all selected regions, a significant anomaly (i.e., extreme wet/dry conditions) in precipitation extremes is observed during spring.

Identification of Tropical-Extratropical Interactions and Extreme Precipitation Events in the Middle East Based On Potential Vorticity and Moisture Transport

NASA Astrophysics Data System (ADS)

de Vries, A. J.; Ouwersloot, H. G.; Feldstein, S. B.; Riemer, M.; El Kenawy, A. M.; McCabe, M. F.; Lelieveld, J.

2018-01-01

Extreme precipitation events in the otherwise arid Middle East can cause flooding with dramatic socioeconomic impacts. Most of these events are associated with tropical-extratropical interactions, whereby a stratospheric potential vorticity (PV) intrusion reaches deep into the subtropics and forces an incursion of high poleward vertically integrated water vapor transport (IVT) into the Middle East. This study presents an object-based identification method for extreme precipitation events based on the combination of these two larger-scale meteorological features. The general motivation for this approach is that precipitation is often poorly simulated in relatively coarse weather and climate models, whereas the synoptic-scale circulation is much better represented. The algorithm is applied to ERA-Interim reanalysis data (1979-2015) and detects 90% (83%) of the 99th (97.5th) percentile of extreme precipitation days in the region of interest. Our results show that stratospheric PV intrusions and IVT structures are intimately connected to extreme precipitation intensity and seasonality. The farther south a stratospheric PV intrusion reaches, the larger the IVT magnitude, and the longer the duration of their combined occurrence, the more extreme the precipitation. Our algorithm detects a large fraction of the climatological rainfall amounts (40-70%), heavy precipitation days (50-80%), and the top 10 extreme precipitation days (60-90%) at many sites in southern Israel and the northern and western parts of Saudi Arabia. This identification method provides a new tool for future work to disentangle teleconnections, assess medium-range predictability, and improve understanding of climatic changes of extreme precipitation in the Middle East and elsewhere.

Air pollution or global warming: Attribution of extreme precipitation changes in eastern China—Comments on "Trends of extreme precipitation in Eastern China and their possible causes"

NASA Astrophysics Data System (ADS)

Wang, Yuan

2015-10-01

The recent study "Trends of Extreme Precipitation in Eastern China and Their Possible Causes" attributed the observed decrease/increase of light/heavy precipitation in eastern China to global warming rather than the regional aerosol effects. However, there exist compelling evidence from previous long-term observations and numerical modeling studies, suggesting that anthropogenic pollution is closely linked to the recent changes in precipitation intensity because of considerably modulated cloud physical properties by aerosols in eastern China. Clearly, a quantitative assessment of the aerosol and greenhouse effects on the regional scale is required to identify the primary cause for the extreme precipitation changes.

Reclaiming metallic material from an article comprising a non-metallic friable substrate

DOEpatents

Bohland, John Raphael; Anisimov, Igor Ivanovich; Dapkus, Todd James; Sasala, Richard Anthony; Smigielski, Ken Alan; Kamm, Kristin Danielle

2000-01-01

A method for reclaiming a metallic material from a article including a non-metallic friable substrate. The method comprising crushing the article into a plurality of pieces. An acidic solution capable of dissolving the metallic material is provided dissolving the metallic material in the acidic material to form an etchant effluent. The etchant effluent is separated from the friable substrate. A precipitation agent, capable of precipitating the metallic material, is added to the etchant effluent to precipitate out the metallic material from the etchant effluent. The metallic material is then recovered.

Method for removing trace pollutants from aqueous solutions

DOEpatents

Silver, Gary L.

1986-01-01

A method of substantially removing a trace metallic contaminant from a liquid containing the same comprises, adding an oxidizing agent to a liquid containing a trace amount of a metallic contaminant of a concentration of up to about 10.sup.-1 ppm, the oxidizing agent being one which oxidizes the contaminant to form an oxidized product which is insoluble in the liquid and precipitates therefrom, and the conditions of the addition being selected to ensure that the precipitation of the oxidized product is homogeneous, and separating the homogeneously precipitated product from the liquid.

Rainfall frequency analysis for ungauged sites using satellite precipitation products

NASA Astrophysics Data System (ADS)

Gado, Tamer A.; Hsu, Kuolin; Sorooshian, Soroosh

2017-11-01

The occurrence of extreme rainfall events and their impacts on hydrologic systems and society are critical considerations in the design and management of a large number of water resources projects. As precipitation records are often limited or unavailable at many sites, it is essential to develop better methods for regional estimation of extreme rainfall at these partially-gauged or ungauged sites. In this study, an innovative method for regional rainfall frequency analysis for ungauged sites is presented. The new method (hereafter, this is called the RRFA-S) is based on corrected annual maximum series obtained from a satellite precipitation product (e.g., PERSIANN-CDR). The probability matching method (PMM) is used here for bias correction to match the CDF of satellite-based precipitation data with the gauged data. The RRFA-S method was assessed through a comparative study with the traditional index flood method using the available annual maximum series of daily rainfall in two different regions in USA (11 sites in Colorado and 18 sites in California). The leave-one-out cross-validation technique was used to represent the ungauged site condition. Results of this numerical application have found that the quantile estimates obtained from the new approach are more accurate and more robust than those given by the traditional index flood method.

Variation of Runoff and Precipitation in the Hekou-Longmen Region of the Yellow River Based on Elasticity Analysis

PubMed Central

Li, Erhui; Mu, Xingmin; Zhao, Guangju; Gao, Peng; Shao, Hongbo

2014-01-01

Precipitation is very important to the formation of runoff, and studying of runoff variation and its response to precipitation has practical significance to sustainable utilization of water resources. The study used Mann-Kendall test, anomaly accumulation method, and precipitation elasticity of runoff method to analyze the changes in the relation of precipitation and runoff and the contribution of precipitation to runoff change in the Hekou-Longmen region (from 1957 to 2010), Huangfuchuan watershed (from 1954 to 2010), and Yanhe watershed (from 1952 to 2010) in the middle reaches of the Yellow River. The results showed that runoff appeared a significant decreasing trend (P = 0.01) while it was not significant in precipitation in all study areas. In particular, the reductions of average annual runoff in the Hekou-Longmen region, Huangfuchuan watershed, and Yanhe watershed were 72.7%, 87.5%, and 32.2%, respectively, during 2000–2010 compared to the 1950s. There existed two abrupt change points of the runoff in the Hekou-Longmen region and Huangfuchuan watershed, which were detected in 1979 and 1998. But in the Yanhe watershed only one abrupt change point was found in 1996. The precipitation elasticities of runoff were 1.11, 1.09, and 1.26, respectively, and the contributions of precipitation on runoff reduction were 26.4%, 17.9%, and 31.6%, respectively, in the Hekou-Longmen region, Huangfuchuan watershed, and Yanhe watershed. PMID:24955424

Variation of runoff and precipitation in the Hekou-Longmen region of the Yellow River based on elasticity analysis.

PubMed

Li, Erhui; Mu, Xingmin; Zhao, Guangju; Gao, Peng; Shao, Hongbo

2014-01-01

Precipitation is very important to the formation of runoff, and studying of runoff variation and its response to precipitation has practical significance to sustainable utilization of water resources. The study used Mann-Kendall test, anomaly accumulation method, and precipitation elasticity of runoff method to analyze the changes in the relation of precipitation and runoff and the contribution of precipitation to runoff change in the Hekou-Longmen region (from 1957 to 2010), Huangfuchuan watershed (from 1954 to 2010), and Yanhe watershed (from 1952 to 2010) in the middle reaches of the Yellow River. The results showed that runoff appeared a significant decreasing trend (P = 0.01) while it was not significant in precipitation in all study areas. In particular, the reductions of average annual runoff in the Hekou-Longmen region, Huangfuchuan watershed, and Yanhe watershed were 72.7%, 87.5%, and 32.2%, respectively, during 2000-2010 compared to the 1950s. There existed two abrupt change points of the runoff in the Hekou-Longmen region and Huangfuchuan watershed, which were detected in 1979 and 1998. But in the Yanhe watershed only one abrupt change point was found in 1996. The precipitation elasticities of runoff were 1.11, 1.09, and 1.26, respectively, and the contributions of precipitation on runoff reduction were 26.4%, 17.9%, and 31.6%, respectively, in the Hekou-Longmen region, Huangfuchuan watershed, and Yanhe watershed.

Extraction of Ni (II) from Spent Hydrodesulfurization HDS Catalyst Through Leaching and Electroless Precipitation of Ni(OH)2

NASA Astrophysics Data System (ADS)

Pradhan, Sangita R.; Dash, Barsha; Sanjay, Kali; Subbaiah, T.

2013-04-01

The extraction of nickel (II) from a spent hydro-desulfurization catalyst containing 11.6 pct Ni was carried out through sulfuric acid leaching. Variations of parameters such as the concentration of acid, temperature, and time, were studied and optimized. Nickel hydroxide was precipitated from the leach liquor via neutralization with 1 M sodium hydroxide up to pH 12 in three different methods: normal neutralization precipitation, and then neutralization precipitation followed by aging at 353 K (80 °C) for 4 hours and neutralization of the leach liquor with 10 pct (v/v) of 0.1 N sodium lauryl sulfate. X-ray diffraction (XRD) and transmission electron microscopy (TEM) microanalysis shows a difference in crystallinity with the method of precipitation. The nickel hydroxide contains Cu(II), Co(II), Zn(II), and Mn(II) as trace impurities. The discharge capacities of the precipitated nickel hydroxides were 120 mAhg-1, 140.72 mAhg-1, and 145.2 mAhg-1 for aged sample, sample without surfactant, and with surfactant respectively.

Precipitation Interpolation by Multivariate Bayesian Maximum Entropy Based on Meteorological Data in Yun- Gui-Guang region, Mainland China

NASA Astrophysics Data System (ADS)

Wang, Chaolin; Zhong, Shaobo; Zhang, Fushen; Huang, Quanyi

2016-11-01

Precipitation interpolation has been a hot area of research for many years. It had close relation to meteorological factors. In this paper, precipitation from 91 meteorological stations located in and around Yunnan, Guizhou and Guangxi Zhuang provinces (or autonomous region), Mainland China was taken into consideration for spatial interpolation. Multivariate Bayesian maximum entropy (BME) method with auxiliary variables, including mean relative humidity, water vapour pressure, mean temperature, mean wind speed and terrain elevation, was used to get more accurate regional distribution of annual precipitation. The means, standard deviations, skewness and kurtosis of meteorological factors were calculated. Variogram and cross- variogram were fitted between precipitation and auxiliary variables. The results showed that the multivariate BME method was precise with hard and soft data, probability density function. Annual mean precipitation was positively correlated with mean relative humidity, mean water vapour pressure, mean temperature and mean wind speed, negatively correlated with terrain elevation. The results are supposed to provide substantial reference for research of drought and waterlog in the region.

Direct and indirect effects of climate change on a prairie plant community.

PubMed

Adler, Peter B; Leiker, James; Levine, Jonathan M

2009-09-03

Climate change directly affects species by altering their physical environment and indirectly affects species by altering interspecific interactions such as predation and competition. Recent studies have shown that the indirect effects of climate change may amplify or counteract the direct effects. However, little is known about the the relative strength of direct and indirect effects or their potential to impact population persistence. We studied the effects of altered precipitation and interspecific interactions on the low-density tiller growth rates and biomass production of three perennial grass species in a Kansas, USA mixed prairie. We transplanted plugs of each species into local neighborhoods of heterospecific competitors and then exposed the plugs to a factorial manipulation of growing season precipitation and neighbor removal. Precipitation treatments had significant direct effects on two of the three species. Interspecific competition also had strong effects, reducing low-density tiller growth rates and aboveground biomass production for all three species. In fact, in the presence of competitors, (log) tiller growth rates were close to or below zero for all three species. However, we found no convincing evidence that per capita competitive effects changed with precipitation, as shown by a lack of significant precipitation x competition interactions. We found little evidence that altered precipitation will influence per capita competitive effects. However, based on species' very low growth rates in the presence of competitors in some precipitation treatments, interspecific interactions appear strong enough to affect the balance between population persistence and local extinction. Therefore, ecological forecasting models should include the effect of interspecific interactions on population growth, even if such interaction coefficients are treated as constants.

Can bias correction and statistical downscaling methods improve the skill of seasonal precipitation forecasts?

NASA Astrophysics Data System (ADS)

Manzanas, R.; Lucero, A.; Weisheimer, A.; Gutiérrez, J. M.

2018-02-01

Statistical downscaling methods are popular post-processing tools which are widely used in many sectors to adapt the coarse-resolution biased outputs from global climate simulations to the regional-to-local scale typically required by users. They range from simple and pragmatic Bias Correction (BC) methods, which directly adjust the model outputs of interest (e.g. precipitation) according to the available local observations, to more complex Perfect Prognosis (PP) ones, which indirectly derive local predictions (e.g. precipitation) from appropriate upper-air large-scale model variables (predictors). Statistical downscaling methods have been extensively used and critically assessed in climate change applications; however, their advantages and limitations in seasonal forecasting are not well understood yet. In particular, a key problem in this context is whether they serve to improve the forecast quality/skill of raw model outputs beyond the adjustment of their systematic biases. In this paper we analyze this issue by applying two state-of-the-art BC and two PP methods to downscale precipitation from a multimodel seasonal hindcast in a challenging tropical region, the Philippines. To properly assess the potential added value beyond the reduction of model biases, we consider two validation scores which are not sensitive to changes in the mean (correlation and reliability categories). Our results show that, whereas BC methods maintain or worsen the skill of the raw model forecasts, PP methods can yield significant skill improvement (worsening) in cases for which the large-scale predictor variables considered are better (worse) predicted by the model than precipitation. For instance, PP methods are found to increase (decrease) model reliability in nearly 40% of the stations considered in boreal summer (autumn). Therefore, the choice of a convenient downscaling approach (either BC or PP) depends on the region and the season.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daleu, C. L.; Plant, R. S.; Woolnough, S. J.

Here, as part of an international intercomparison project, a set of single-column models (SCMs) and cloud-resolving models (CRMs) are run under the weak-temperature gradient (WTG) method and the damped gravity wave (DGW) method. For each model, the implementation of the WTG or DGW method involves a simulated column which is coupled to a reference state defined with profiles obtained from the same model in radiative-convective equilibrium. The simulated column has the same surface conditions as the reference state and is initialized with profiles from the reference state. We performed systematic comparison of the behavior of different models under a consistentmore » implementation of the WTG method and the DGW method and systematic comparison of the WTG and DGW methods in models with different physics and numerics. CRMs and SCMs produce a variety of behaviors under both WTG and DGW methods. Some of the models reproduce the reference state while others sustain a large-scale circulation which results in either substantially lower or higher precipitation compared to the value of the reference state. CRMs show a fairly linear relationship between precipitation and circulation strength. SCMs display a wider range of behaviors than CRMs. Some SCMs under the WTG method produce zero precipitation. Within an individual SCM, a DGW simulation and a corresponding WTG simulation can produce different signed circulation. When initialized with a dry troposphere, DGW simulations always result in a precipitating equilibrium state. The greatest sensitivities to the initial moisture conditions occur for multiple stable equilibria in some WTG simulations, corresponding to either a dry equilibrium state when initialized as dry or a precipitating equilibrium state when initialized as moist. Multiple equilibria are seen in more WTG simulations for higher SST. In some models, the existence of multiple equilibria is sensitive to some parameters in the WTG calculations.« less

Scale effects on information theory-based measures applied to streamflow patterns in two rural watersheds

NASA Astrophysics Data System (ADS)

Pan, Feng; Pachepsky, Yakov A.; Guber, Andrey K.; McPherson, Brian J.; Hill, Robert L.

2012-01-01

SummaryUnderstanding streamflow patterns in space and time is important for improving flood and drought forecasting, water resources management, and predictions of ecological changes. Objectives of this work include (a) to characterize the spatial and temporal patterns of streamflow using information theory-based measures at two thoroughly-monitored agricultural watersheds located in different hydroclimatic zones with similar land use, and (b) to elucidate and quantify temporal and spatial scale effects on those measures. We selected two USDA experimental watersheds to serve as case study examples, including the Little River experimental watershed (LREW) in Tifton, Georgia and the Sleepers River experimental watershed (SREW) in North Danville, Vermont. Both watersheds possess several nested sub-watersheds and more than 30 years of continuous data records of precipitation and streamflow. Information content measures (metric entropy and mean information gain) and complexity measures (effective measure complexity and fluctuation complexity) were computed based on the binary encoding of 5-year streamflow and precipitation time series data. We quantified patterns of streamflow using probabilities of joint or sequential appearances of the binary symbol sequences. Results of our analysis illustrate that information content measures of streamflow time series are much smaller than those for precipitation data, and the streamflow data also exhibit higher complexity, suggesting that the watersheds effectively act as filters of the precipitation information that leads to the observed additional complexity in streamflow measures. Correlation coefficients between the information-theory-based measures and time intervals are close to 0.9, demonstrating the significance of temporal scale effects on streamflow patterns. Moderate spatial scale effects on streamflow patterns are observed with absolute values of correlation coefficients between the measures and sub-watershed area varying from 0.2 to 0.6 in the two watersheds. We conclude that temporal effects must be evaluated and accounted for when the information theory-based methods are used for performance evaluation and comparison of hydrological models.

LAB-SCALE DEMONSTRATION OF PLUTONIUM PURIFICATION BY ANION EXCHANGE, PLUTONIUM (IV) OXALATE PRECIPITATION, AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowder, M.; Pierce, R.

2012-08-22

H-Canyon and HB-Line are tasked with the production of PuO{sub 2} from a feed of plutonium metal. The PuO{sub 2} will provide feed material for the MOX Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, the solution will be transferred to HB-Line for purification by anion exchange. Subsequent unit operations include Pu(IV) oxalate precipitation, filtration and calcination to form PuO{sub 2}. This report details the results from SRNL anion exchange, precipitation, filtration, calcination, and characterization tests, as requested by HB-Line1 and described in the task plan. This study involved an 80-g batch of Pu and employed testmore » conditions prototypical of HB-Line conditions, wherever feasible. In addition, this study integrated lessons learned from earlier anion exchange and precipitation and calcination studies. H-Area Engineering selected direct strike Pu(IV) oxalate precipitation to produce a more dense PuO{sub 2} product than expected from Pu(III) oxalate precipitation. One benefit of the Pu(IV) approach is that it eliminates the need for reduction by ascorbic acid. The proposed HB-Line precipitation process involves a digestion time of 5 minutes after the time (44 min) required for oxalic acid addition. These were the conditions during HB-line production of neptunium oxide (NpO{sub 2}). In addition, a series of small Pu(IV) oxalate precipitation tests with different digestion times were conducted to better understand the effect of digestion time on particle size, filtration efficiency and other factors. To test the recommended process conditions, researchers performed two nearly-identical larger-scale precipitation and calcination tests. The calcined batches of PuO{sub 2} were characterized for density, specific surface area (SSA), particle size, moisture content, and impurities. Because the 3013 Standard requires that the calcination (or stabilization) process eliminate organics, characterization of PuO{sub 2} batches monitored the presence of oxalate by thermogravimetric analysis-mass spectrometry (TGA-MS). To use the TGA-MS for carbon or oxalate content, some method development will be required. However, the TGA-MS is already used for moisture measurements. Therefore, SRNL initiated method development for the TGA-MS to allow quantification of oxalate or total carbon. That work continues at this time and is not yet ready for use in this study. However, the collected test data can be reviewed later as those analysis tools are available.« less

Seeding Experiment of Liquid Carbon Dioxide for Enhancing Winter-time Precipitation in Saga Prefecture,Northern Kyushu,Japan

NASA Astrophysics Data System (ADS)

Wakimizu, K.; Nishiyama, K.; Tomine, K.; Maki, T.; Suzuki, Y.; Morita, O.

2012-12-01

Many droughts (shortage of water) have broken out by extreme small amount rainfall in recent Japan. So far,in order to prevent these droughts,artificial rainfall methods with 'AgI' or 'dry ice' have been widely used in Japan. However,these methods have many problems,which a large amount of overcooling liquid in the cumulus cloud was not able to be converted into precipitation efficiently. So as to solve these problems,new artificial rainfall method using liquid carbon dioxide (LC) was proposed by Fukuta (1996). This new method consists of the generation of ice particles by homogeneous nucleation using LC and the subsequent more effective growth for ice particles without competition process. And, this method is called 'Low-Level Penetration Seeding of Homogeneous Ice Nucleant (LOLEPSHIN)' ; this induces a 'Roll-up Expansion of Twin Horizontal Ice-crystal Thermals (RETHIT)' and a subsequent 'Falling growth-Induced Lateral Air Spreading (FILAS)'. This LC method was applied to thin super-cooled cumulus clouds in Saga prefecture, Northern Kyushu, Japan on February 4,2006. The seeding airplane took off the Atugi Airport in Kanagawa Prefecture toward the Iki Island around 0830JST. Many cloud bands were cofirmed in the flight going to the experimental area and the cloud base temperature was approximately -9C (1200m). Scince some young developing thin cumuli were found over the Iki Island, LC seeding to these clouds was carried out two times from 0841JST until 0919JST penetrating the -9C (1200m) altitude. The first precipitation seeding ebded in failure. The second penetration seeding was done for 115 seconds around 0917JST. This penetration led to success of developing one artificial echo (Echo I) in the leeward side of the Iki Island. Eco I moved from NNW to SSW. The maximum area of Echo I were 48km2 (at 1033JST) and first comfirmed by the Kyushu University radar (KU radar) at 1006JST (46 min. after LC seeding) around Mt.Sefuri in Saga Prefecture. It can be inferred that ice perticles formed by LC seeding grew to the precipitable size and resultant snowfall was detected by radar in approximately 120 min. after seeding operation. In this study, based on these observed facts, optimum design for enhancing winter-time water resources by LC seeding method was suggested. Successive low-level horizontal penetrations of operational aircraft with seeding LC into many moving super-cooled cumuli towards the Japan Islands will lead to the spreading of cloud volume and subsequent coversion of large amount of iv active cloud volume into newly exploited artificial precipitation. As a result, these experiments succeeded, and the total amount of estimated radar precipitation of the be able to secure a large amount of water resource from these experiment results.

A cost effective cultivation medium for biocalcification of Bacillus pasteurii KCTC 3558 and its effect on cement cubes properties.

PubMed

Yoosathaporn, S; Tiangburanatham, P; Bovonsombut, S; Chaipanich, A; Pathom-Aree, W

2016-01-01

Application of carbonate precipitation induced by Bacillus pasteurii for improving some properties of cement has been reported. However, it is not yet successful in commercial scale due to the high cost of cultivation medium. This is the first report on the application of effluent from chicken manure bio-gas plant, a high protein content agricultural waste, as an alternative growth medium for carbonate precipitation by B. pasteurii KCTC3558. Urease activity of B. pasteurii KCTC3558 cultured in chicken manure effluent medium and other three standard media were examined using phenate method. The highest urease production was achieved in chicken manure effluent medium (16.756Umg(-1) protein). Cost per liter of chicken manure effluent medium is up to 88.2% lower than other standard media. The most effective cultivation media was selected for carbonate precipitation study in cement cubes. Water absorption, voids, apparent density and compressive strength of cement cubes were measured according to the ASTM standard. The correlation between the increasing density and compressive strength of bacterial added cement cube was evident. The density of bacterial cement cube is 5.1% higher than control while the compressive strength of cement mixed with bacterial cells in chicken manure effluent medium increases up to 30.2% compared with control. SEM and XRD analysis also found the crystalline phase of calcium carbonate within bacterial cement which confirmed that the increasing density and compressive strength were resulted from bacterial carbonate precipitation. This study indicated that the effluent from chicken manure bio-gas plant could be used as an alternative cost effective culture medium for cultivation and biocalcification of B. pasteurii KCTC3558 in cement. Copyright © 2016. Published by Elsevier GmbH.

Alternate method of source preparation for alpha spectrometry: No electrodeposition, no hydrofluoric acid

DOE PAGES

Kurosaki, Hiromu; Mueller, Rebecca J.; Lambert, Susan B.; ...

2016-07-15

An alternate method of preparing actinide alpha counting sources was developed in place of electrodeposition or lanthanide fluoride micro-precipitation. The method uses lanthanide hydroxide micro-precipitation to avoid the use of hazardous hydrofluoric acid. Lastly, it provides a quicker, simpler, and safer way of preparing actinide alpha counting sources in routine, production-type laboratories that process many samples daily.

Runoff sensitivity to climate change in the Nile River Basin

NASA Astrophysics Data System (ADS)

Hasan, Emad; Tarhule, Aondover; Kirstetter, Pierre-Emmanuel; Clark, Race; Hong, Yang

2018-06-01

In data scarce basins, such as the Nile River Basin (NRB) in Africa, constraints related to data availability, quality, and access often complicate attempts to estimate runoff sensitivity using conventional methods. In this paper, we show that by integrating the concept of the aridity index (AI) (derived from the Budyko curve) and climate elasticity, we can obtain the first order response of the runoff sensitivity using minimal data input and modeling expertise or experience. The concept of runoff elasticity relies on the fact that the energy available for evapotranspiration plays a major role in determining whether the precipitation received within a drainage basin generates runoff. The approach does not account for human impacts on runoff modification and or diversions. By making use of freely available gauge-corrected satellite data for precipitation, temperature, runoff, and potential evapotranspiration, we derived the sensitivity indicator (β) to determine the runoff response to changes in precipitation and temperature for four climatic zones in the NRB, namely, tropical, subtropical, semiarid and arid zones. The proposed sensitivity indicator can be partitioned into different elasticity components i.e: precipitation (εp), potential evapotranspiration (εETp), temperature (εT) and the total elasticity (εtot) . These elasticities allow robust quantification of the runoff response to the potential changes in precipitation and temperature with a high degree of accuracy. Results indicate that the tropical zone is energy-constrained with low sensitivity, (β < 1.0) , implying that input precipitation exceeds the amounts that can be evaporated given the available energy. The subtropical zone is subdivided into two distinct regions, the lowland (Machar and Sudd marshes), and the highland area (Blue Nile Basin), where each area has a unique sensitivity. The lowland area has high sensitivity, (β > 1.0) . The subtropical-highland zone moves between energy-limited to water-limited conditions during periods of wet and dry spells with varying sensitivity. The semiarid and arid zones are water limited, with high sensitivity, (β > 1.0) . The calculated runoff elasticities show that a 10% decrease in precipitation leads to a decrease in runoff of between 19% in the tropical zone and 30% in the arid zones. On the other hand, a 10% precipitation increase leads to a runoff increase of 14% in the tropical zone and 22% in the arid zone. The estimated runoff changes are consistent with the result obtained using other methods. Thus, the elasticity approach combines data parsimony and analytical simplicity to produce results that are practically useful for most purposes while facilitating communication with stakeholders with different levels of scientific knowledge. More research is needed to extend the application of the method to incorporate the effects of human activities, and land use change.

BFS Simulation and Experimental Analysis of the Effect of Ti Additions on the Structure of NiAl

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Noebe, Ronald D.; Ferrante,John; Garg, Anita; Honecy, Frank S.; Amador, Carlos

1999-01-01

The Bozzolo-Ferrante-Smith (BFS) method for alloy energetics is applied to the study of ternary additions to NiAl. A description of the method and its application to alloy design is given. Two different approaches are used in the analysis of the effect of Ti additions to NiAl. First, a thorough analytical study is performed, where the energy of formation, lattice parameter and bulk modulus are calculated for a large number of possible atomic distributions of Ni, Al and Ti. Substitutional site preference schemes and formation of precipitates are thus predicted and analyzed. The second approach used consists of the determination of temperature effects on the final results, as obtained by performing a number of large scale numerical simulations using the Monte Carlo-Metropolis procedure and BFS for the calculation of the energy at every step in the simulation. The results indicate a sharp preference of Ti for Al sites in Ni-rich NiAl alloys and the formation of ternary Heusler precipitates beyond the predicted solubility limit of 5 at. % Ti. Experimental analysis of three Ni-Al-Ti alloys confirms the theoretical predictions.

Atomistic Simulations and Experimental Analysis of the Effect of Ti Additions on the Structure of NiAl

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Noebe, Ronald D.; Ferrante, John; Garg, Anita; Amador, Carlos

1997-01-01

The Bozzolo-Ferrante-Smith (BFS) semiempirical method for alloy energetics is applied to the study of ternary additions to NiAl alloys. A detailed description of the method and its application to alloy design is given. Two different approaches are used in the analysis of the effect of Ti additions to NiAl. First, a thorough analytical study is performed, where the energy of formation, lattice parameter and bulk modulus are calculated for hundreds of possible atomic distributions of Ni, Al and Ti. Substitutional site preference schemes and formation of precipitates are thus predicted and analyzed. The second approach used consists of the determination of temperature effects on the final results, as obtained by performing a number of large scale numerical simulations using the Monte Carlo - Metropolis procedure and BFS for the calculation of the energy at every step in the simulation. The results indicate a sharp preference of Ti for Al sites in Ni-rich NiAl alloys and the formation of ternary Heusler precipitates beyond the predicted solubility limit of 5 at. % Ti. Experimental analysis of three NiAl+Ti alloys confirms the theoretical predictions.

Effects of solution concentration and capping agents on the properties of potassium titanyl phosphate noparticles synthesized using a co-precipitation method

NASA Astrophysics Data System (ADS)

Gharibshahian, E.; Jafar Tafershi, M.; Fazli, M.

2018-05-01

In this study, KTiOPO4 (KTP) nanoparticles were synthesized using a co-precipitation method. The effects of the solution concentration (M) and capping agents, such as PVA, oxalic acid, glycine, triethanolamine, and L-alanine, on the structural, microstructural, and optical properties of the products were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. Decreasing the solution concentration decreased the crystallite size from 53.07 nm (for M = 2) to 39.42 nm (for M = 0.5). After applying different capping agents to the sample at the optimum concentration (M = 0.5), the crystallite size decreased again and grains as small as 10.61 nm were obtained. XRD and FTIR analyses indicated the formation of KTP nanoparticles with an orthorhombic structure in all of the samples. The optical band gap increased as the crystallite size decreased. Different morphological patterns such as spherical, needle shaped, polyhedron, and tablet forms were observed in the nanoparticles, which were correlated with the effects of the capping agents employed.

Investigating the effects of climate variations on bacillary dysentery incidence in northeast China using ridge regression and hierarchical cluster analysis

PubMed Central

Huang, Desheng; Guan, Peng; Guo, Junqiao; Wang, Ping; Zhou, Baosen

2008-01-01

Background The effects of climate variations on bacillary dysentery incidence have gained more recent concern. However, the multi-collinearity among meteorological factors affects the accuracy of correlation with bacillary dysentery incidence. Methods As a remedy, a modified method to combine ridge regression and hierarchical cluster analysis was proposed for investigating the effects of climate variations on bacillary dysentery incidence in northeast China. Results All weather indicators, temperatures, precipitation, evaporation and relative humidity have shown positive correlation with the monthly incidence of bacillary dysentery, while air pressure had a negative correlation with the incidence. Ridge regression and hierarchical cluster analysis showed that during 1987–1996, relative humidity, temperatures and air pressure affected the transmission of the bacillary dysentery. During this period, all meteorological factors were divided into three categories. Relative humidity and precipitation belonged to one class, temperature indexes and evaporation belonged to another class, and air pressure was the third class. Conclusion Meteorological factors have affected the transmission of bacillary dysentery in northeast China. Bacillary dysentery prevention and control would benefit from by giving more consideration to local climate variations. PMID:18816415

Assessment of short- and long-term memory in trends of major climatic variables over Iran: 1966-2015

NASA Astrophysics Data System (ADS)

Mianabadi, Ameneh; Shirazi, Pooya; Ghahraman, Bijan; Coenders-Gerrits, A. M. J.; Alizadeh, Amin; Davary, Kamran

2018-02-01

In arid and semi-arid regions, water scarcity is the crucial issue for crop production. Identifying the spatial and temporal trends in aridity, especially during the crop-growing season, is important for farmers to manage their agricultural practices. This will become especially relevant when considering climate change projections. To reliably determine the actual trends, the influence of short- and long-term memory should be removed from the trend analysis. The objective of this study is to investigate the effect of short- and long-term memory on estimates of trends in two aridity indicators—the inverted De Martonne (ϕ IDM ) and Budyko (ϕ B ) indices. The analysis is done using precipitation and temperature data over Iran for a 50-year period (1966-2015) at three temporal scales: annual, wheat-growing season (October-June), and maize-growing season (May-November). For this purpose, the original and the modified Mann-Kendall tests (i.e., modified by three methods of trend free pre-whitening (TFPT), effective sample size (ESS), and long-term persistence (LTP)) are used to investigate the temporal trends in aridity indices, precipitation, and temperature by taking into account the effect of short- and long-term memory. Precipitation and temperature data were provided by the Islamic Republic of Iran Meteorological Organization (IRIMO). The temporal trend analysis showed that aridity increased from 1966 to 2015 at the annual and wheat-growing season scales, which is due to a decreasing trend in precipitation and an increasing trend in mean temperature at these two timescales. The trend in aridity indices was decreasing in the maize-growing season, since precipitation has an increasing trend for most parts of Iran in that season. The increasing trend in aridity indices is significant in Western Iran, which can be related to the significantly more negative trend in precipitation in the West. This increasing trend in aridity could result in an increasing crop water requirement and a significant reduction in the crop production and water use efficiency. Furthermore, the modified Mann-Kendall tests indicated that unlike temperature series, precipitation, ϕ IDM , and ϕ B series are not affected by short- and long-term memory. Our results can help decision makers and water resource managers to adopt appropriate policy strategies for sustainable development in the field of irrigated agriculture and water resources management.

Effective removal of coordinated copper from wastewater using a new dithiocarbamate-type supramolecular heavy metal precipitant.

PubMed

Fu, Fenglian; Zeng, Haiyan; Cai, Qinhong; Qiu, Rongliang; Yu, Jimmy; Xiong, Ya

2007-11-01

A new dithiocarbamate-type heavy metal precipitant, sodium 1,3,5-hexahydrotriazinedithiocarbamate (HTDC), was prepared and used to remove coordinated copper from wastewater. In the reported dithiocarbamate-type precipitants, HTDC possesses the highest percentage of the effective functional groups. It could effectively precipitate copper to less than 0.5mgl(-1) from both synthetic and actual industrial wastewater containing CuEDTA in the range of pH 3-9. UV-vis spectral investigation and elemental analysis suggested that the precipitate was a kind of coordination supramolecular compound, [Cu(3)(HTDC)(2)](n). The toxicity characteristic leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) indicated that the supramolecular precipitate was non-hazardous and stable in weak acid and alkaline conditions. Tests of an anion exchange resin D231 provided a clue to simultaneously remove excess HTDC and residual CuEDTA in practical process of wastewater treatment.