WorldWideScience

Sample records for precipitation processes cloud-resolving

  1. Tropical Oceanic Precipitation Processes Over Warm Pool: 2D and 3D Cloud Resolving Model Simulations

    Science.gov (United States)

    Tao, W.-K.; Johnson, D.; Simpson, J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Rainfall is a key link in the hydrologic cycle as well as the primary heat source for the atmosphere. The vertical distribution of convective latent-heat release modulates the large-scale circulations of the topics. Furthermore, changes in the moisture distribution at middle and upper levels of the troposphere can affect cloud distributions and cloud liquid water and ice contents. How the incoming solar and outgoing longwave radiation respond to these changes in clouds is a major factor in assessing climate change. Present large-scale weather and climate model simulate processes only crudely, reducing confidence in their predictions on both global and regional scales. One of the most promising methods to test physical parameterizations used in General Circulation Models (GCMs) and climate models is to use field observations together with Cloud Resolving Models (CRMs). The CRMs use more sophisticated and physically realistic parameterizations of cloud microphysical processes, and allow for their complex interactions with solar and infrared radiative transfer processes. The CRMs can reasonably well resolve the evolution, structure, and life cycles of individual clouds and clouds systems. The major objective of this paper is to investigate the latent heating, moisture and momentum budgets associated with several convective systems developed during the TOGA COARE IFA - westerly wind burst event (late December, 1992). The tool for this study is the Goddard Cumulus Ensemble (GCE) model which includes a 3-class ice-phase microphysics scheme.

  2. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2008-01-01

    Aerosols and especially their effect on clouds are one of the key components of the climate system and the hydrological cycle [Ramanathan et al., 2001]. Yet, the aerosol effect on clouds remains largely unknown and the processes involved not well understood. A recent report published by the National Academy of Science states "The greatest uncertainty about the aerosol climate forcing - indeed, the largest of all the uncertainties about global climate forcing - is probably the indirect effect of aerosols on clouds [NRC, 2001]." The aerosol effect on clouds is often categorized into the traditional "first indirect (i.e., Twomey)" effect on the cloud droplet sizes for a constant liquid water path [Twomey, 1977] and the "semi-direct" effect on cloud coverage [e.g., Ackerman et al ., 2001]." Enhanced aerosol concentrations can also suppress warm rain processes by producing a narrow droplet spectrum that inhibits collision and coalescence processes [e.g., Squires and Twomey, 1961; Warner and Twomey, 1967; Warner, 1968; Rosenfeld, 19991. The aerosol effect on precipitation processes, also known as the second type of aerosol indirect effect [Albrecht, 1989], is even more complex, especially for mixed-phase convective clouds. Table 1 summarizes the key observational studies identifying the microphysical properties, cloud characteristics, thermodynamics and dynamics associated with cloud systems from high-aerosol continental environments. For example, atmospheric aerosol concentrations can influence cloud droplet size distributions, warm-rain process, cold-rain process, cloud-top height, the depth of the mixed phase region, and occurrence of lightning. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing an enhanced source of cloud condensation nuclei (CCN). Hypotheses have been developed to explain the effect of urban regions on convection and precipitation [van den Heever and Cotton, 2007 and Shepherd, 2005

  3. The Role of Aerosols on Precipitation Processes: Cloud Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Li, X.; Matsui, T.

    2012-01-01

    identify the impact of ice processes, radiation and large-scale influence on cloud-aerosol interactive processes, especially regarding surface rainfall amounts and characteristics (i.e., heavy or convective versus light or stratiform types). In addition, an inert tracer was included to follow the vertical redistribution of aerosols by cloud processes. We will also give a brief review from observational evidence on the role of aerosol on precipitation processes.

  4. Precipitation processes developed during TOGA COARE (1992), GATE (1974), SCSMEX (1998), and KWAJEX (1999): 3D Cloud Resolving Model Simulation

    Science.gov (United States)

    Tao, W.-K.

    2006-01-01

    Real clouds and cloud systems are inherently three-dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D). A few 3D CRMs have been used to study the response of clouds to large-scale forcing. In these 3D simulations, the model domain was small, and the integration time was 6 hours. Only recently have 3D experiments been performed for multi-day periods for tropical cloud systems with large horizontal domains at the National Center for Atmospheric Research (NCAR), NOAA GFDL, the U.K. Met. Office, Colorado State University and NASA Goddard Space Flight Center. An improved 3D Goddard Cumulus Ensemble (GCE) model was recently used to simulate periods during TOGA COARE (December 19-27, 1992), GATE (september 1-7, 1974), SCSMEX (May 18-26, June 2-11, 1998) and KWAJEX (August 7-13, August 18-21, and August 29-September 12, 1999) using a 512 by 512 km domain and 41 vertical layers. The major objectives of this paper are: (1) to identify the differences and similarities in the simulated precipitation processes and their associated surface and water energy budgets in TOGA COARE, GATE, KWAJEX, and SCSMEX, and (2) to asses the impact of microphysics, radiation budget and surface fluxes on the organization of convection in tropics.

  5. A Coupled GCM-Cloud Resolving Modeling System, and a Regional Scale Model to Study Precipitation Processes

    Science.gov (United States)

    Tao, Wei-Kuo

    2007-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a superparameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM), and it has started production runs with two years results (1998 and 1999). Also, at Goddard, we have implemented several Goddard microphysical schemes (2ICE, several 31CE), Goddard radiation (including explicitly calculated cloud optical properties), and Goddard Land Information (LIS, that includes the CLM and NOAH land surface models) into a next generatio11 regional scale model, WRF. In this talk, I will present: (1) A brief review on GCE model and its applications on precipitation processes (microphysical and land processes), (2) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), and preliminary results (the comparison with traditional GCMs), and (3) A discussion on the Goddard WRF version (its developments and applications).

  6. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2012-01-01

    Recently, a detailed spectral-bin microphysical scheme was implemented into the Goddard Cumulus Ensemble (GCE) model. Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and summertime convection over a mid-latitude continent with different concentrations of CCN: a low clean concentration and a high dirty concentration. The impact of atmospheric aerosol concentration on cloud and precipitation will be investigated.

  7. Precipitation Processes developed during ARM (1997), TOGA COARE(1992), GATE(1 974), SCSMEX(1998) and KWAJEX(1999): Consistent 2D and 3D Cloud Resolving Model Simulations

    Science.gov (United States)

    Tao, W.-K.; Shie, C.-H.; Simpson, J.; Starr, D.; Johnson, D.; Sud, Y.

    2003-01-01

    Real clouds and clouds systems are inherently three dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D). A few 3D CRMs have been used to study the response of clouds to large-scale forcing. In these 3D simulations, the model domain was small, and the integration time was 6 hours. Only recently have 3D experiments been performed for multi-day periods for tropical cloud system with large horizontal domains at the National Center for Atmospheric Research. The results indicate that surface precipitation and latent heating profiles are very similar between the 2D and 3D simulations of these same cases. The reason for the strong similarity between the 2D and 3D CRM simulations is that the observed large-scale advective tendencies of potential temperature, water vapor mixing ratio, and horizontal momentum were used as the main forcing in both the 2D and 3D models. Interestingly, the 2D and 3D versions of the CRM used in CSU and U.K. Met Office showed significant differences in the rainfall and cloud statistics for three ARM cases. The major objectives of this project are to calculate and axamine: (1)the surface energy and water budgets, (2) the precipitation processes in the convective and stratiform regions, (3) the cloud upward and downward mass fluxes in the convective and stratiform regions; (4) cloud characteristics such as size, updraft intensity and lifetime, and (5) the entrainment and detrainment rates associated with clouds and cloud systems that developed in TOGA COARE, GATE, SCSMEX, ARM and KWAJEX. Of special note is that the analyzed (model generated) data sets are all produced by the same current version of the GCE model, i.e. consistent model physics and configurations. Trajectory analyse and inert tracer calculation will be conducted to identify the differences and similarities in the organization of convection between simulated 2D and 3D cloud systems.

  8. Role of atmospheric aerosol concentration on deep convective precipitation: Cloud-resolving model simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2007-12-01

    A two-dimensional cloud-resolving model with detailed spectral bin microphysics is used to examine the effect of aerosols on three different deep convective cloud systems that developed in different geographic locations: south Florida, Oklahoma, and the central Pacific. A pair of model simulations, one with an idealized low cloud condensation nuclei (CCN) (clean) and one with an idealized high CCN (dirty environment), is conducted for each case. In all three cases, rain reaches the ground earlier for the low-CCN case. Rain suppression is also evident in all three cases with high CCN. However, this suppression only occurs during the early stages of the simulations. During the mature stages of the simulations the effects of increasing aerosol concentration range from rain suppression in the Oklahoma case to almost no effect in the Florida case to rain enhancement in the Pacific case. The model results suggest that evaporative cooling in the lower troposphere is a key process in determining whether high CCN reduces or enhances precipitation. Stronger evaporative cooling can produce a stronger cold pool and thus stronger low-level convergence through interactions with the low-level wind shear. Consequently, precipitation processes can be more vigorous. For example, the evaporative cooling is more than two times stronger in the lower troposphere with high CCN for the Pacific case. Sensitivity tests also suggest that ice processes are crucial for suppressing precipitation in the Oklahoma case with high CCN. A comparison and review of other modeling studies are also presented.

  9. Mechanisms of diurnal precipitation over the US Great Plains: a cloud resolving model perspective

    Science.gov (United States)

    Lee, Myong-In; Choi, Ildae; Tao, Wei-Kuo; Schubert, Siegfried D.; Kang, In-Sik

    2010-02-01

    The mechanisms of summertime diurnal precipitation in the US Great Plains were examined with the two-dimensional (2D) Goddard Cumulus Ensemble (GCE) cloud-resolving model (CRM). The model was constrained by the observed large-scale background state and surface flux derived from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program’s Intensive Observing Period (IOP) data at the Southern Great Plains (SGP). The model, when continuously-forced by realistic surface flux and large-scale advection, simulates reasonably well the temporal evolution of the observed rainfall episodes, particularly for the strongly forced precipitation events. However, the model exhibits a deficiency for the weakly forced events driven by diurnal convection. Additional tests were run with the GCE model in order to discriminate between the mechanisms that determine daytime and nighttime convection. In these tests, the model was constrained with the same repeating diurnal variation in the large-scale advection and/or surface flux. The results indicate that it is primarily the surface heat and moisture flux that is responsible for the development of deep convection in the afternoon, whereas the large-scale upward motion and associated moisture advection play an important role in preconditioning nocturnal convection. In the nighttime, high clouds are continuously built up through their interaction and feedback with long-wave radiation, eventually initiating deep convection from the boundary layer. Without these upper-level destabilization processes, the model tends to produce only daytime convection in response to boundary layer heating. This study suggests that the correct simulation of the diurnal variation in precipitation requires that the free-atmospheric destabilization mechanisms resolved in the CRM simulation must be adequately parameterized in current general circulation models (GCMs) many of which are overly sensitive to the parameterized boundary layer

  10. Mechanisms of Diurnal Precipitation over the United States Great Plains: A Cloud-Resolving Model Simulation

    Science.gov (United States)

    Lee, M.-I.; Choi, I.; Tao, W.-K.; Schubert, S. D.; Kang, I.-K.

    2010-01-01

    The mechanisms of summertime diurnal precipitation in the US Great Plains were examined with the two-dimensional (2D) Goddard Cumulus Ensemble (GCE) cloud-resolving model (CRM). The model was constrained by the observed large-scale background state and surface flux derived from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program s Intensive Observing Period (IOP) data at the Southern Great Plains (SGP). The model, when continuously-forced by realistic surface flux and large-scale advection, simulates reasonably well the temporal evolution of the observed rainfall episodes, particularly for the strongly forced precipitation events. However, the model exhibits a deficiency for the weakly forced events driven by diurnal convection. Additional tests were run with the GCE model in order to discriminate between the mechanisms that determine daytime and nighttime convection. In these tests, the model was constrained with the same repeating diurnal variation in the large-scale advection and/or surface flux. The results indicate that it is primarily the surface heat and moisture flux that is responsible for the development of deep convection in the afternoon, whereas the large-scale upward motion and associated moisture advection play an important role in preconditioning nocturnal convection. In the nighttime, high clouds are continuously built up through their interaction and feedback with long-wave radiation, eventually initiating deep convection from the boundary layer. Without these upper-level destabilization processes, the model tends to produce only daytime convection in response to boundary layer heating. This study suggests that the correct simulation of the diurnal variation in precipitation requires that the free-atmospheric destabilization mechanisms resolved in the CRM simulation must be adequately parameterized in current general circulation models (GCMs) many of which are overly sensitive to the parameterized boundary layer heating.

  11. Precipitation Processes Developed During ARM (1997), TOGA COARE (1992) GATE (1974), SCSMEX (1998), and KWAJEX (1999): Consistent 3D, Semi-3D and 3D Cloud Resolving Model Simulations

    Science.gov (United States)

    Tao, W.-K.; Hou, A.; Atlas, R.; Starr, D.; Sud, Y.

    2003-01-01

    Real clouds and cloud systems are inherently three-dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D) have been used to study the response of clouds to large-scale forcing. IN these 3D simulators, the model domain was small, and the integration time was 6 hours. Only recently have 3D experiments been performed for multi-day periods for tropical clouds systems with large horizontal domains at the National Center of Atmospheric Research (NCAR) and at NASA Goddard Space Center. At Goddard, a 3D cumulus Ensemble (GCE) model was used to simulate periods during TOGA COARE, GATE, SCSMEX, ARM, and KWAJEX using a 512 by 512 km domain (with 2-km resolution). The result indicate that surface precipitation and latent heating profiles are very similar between the 2D and 3D GCE model simulation. The major objective of this paper are: (1) to assess the performance of the super-parametrization technique, (2) calculate and examine the surface energy (especially radiation) and water budget, and (3) identify the differences and similarities in the organization and entrainment rates of convection between simulated 2D and 3D cloud systems.

  12. Precipitation Processes Developed During ARM (1997), TOGA COARE (1992), GATE (1974), SCSMEX (1998), and KWAJEX (1999): Consistent 2D, Semi-3D and 3D Cloud Resolving Model Simulations

    Science.gov (United States)

    Tao, W-K.

    2003-01-01

    Real clouds and cloud systems are inherently three-dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D). A few 3D CRMs have been used to study the response of clouds to large-scale forcing. In these 3D simulations, the model domain was small, and the integration time was 6 hours. Only recently have 3D experiments been performed for multi-day periods for tropical cloud systems with large horizontal domains at the National Center for Atmospheric Research (NACAR) and at NASA Goddard Space Flight Center . At Goddard, a 3D Goddard Cumulus Ensemble (GCE) model was used to simulate periods during TOGA COARE, SCSMEX and KWAJEX using 512 by 512 km domain (with 2 km resolution). The results indicate that surface precipitation and latent heating profiles are very similar between the 2D and 3D GCE model simulations. The reason for the strong similarity between the 2D and 3D CRM simulations is that the same observed large-scale advective tendencies of potential temperature, water vapor mixing ratio, and horizontal momentum were used as the main focusing in both the 2D and 3D models. Interestingly, the 2D and 3D versions of the CRM used at CSU showed significant differences in the rainfall and cloud statistics for three ARM cases. The major objectives of this paper are: (1) to assess the performance of the super-parameterization technique, (2) calculate and examine the surface energy (especially radiation) and water budgets, and (3) identify the differences and similarities in the organization and entrainment rates of convection between simulated 2D and 3D cloud systems.

  13. Precipitation Processes developed during ARM (1997), TOGA COARE (1992), GATE (1974), SCSMEX (1998), and KWAJEX (1999), Consistent 2D, semi-3D and 3D Cloud Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Hou, A.; Atlas, R.; Starr, D.; Sud, Y.

    2003-01-01

    Real clouds and cloud systems are inherently three-dimensional (3D). Because of the limitations in computer resources, however, most cloud-resolving models (CRMs) today are still two-dimensional (2D). A few 3D CRMs have been used to study the response of clouds to large-scale forcing. In these 3D simulations, the model domain was small, and the integration time was 6 hours. The major objectives of this paper are: (1) to assess the performance of the super-parameterization technique (i.e. is 2D or semi-3D CRM appropriate for the super-parameterization?); (2) calculate and examine the surface energy (especially radiation) and water budgets; (3) identify the differences and similarities in the organization and entrainment rates of convection between simulated 2D and 3D cloud systems.

  14. Edouard's (2014) Intensification: An Investigation of Precipitation and Thermodynamic Symmetrization Using a Cloud-Resolving Ensemble

    Science.gov (United States)

    Alvey, G., III; Zipser, E. J.

    2017-12-01

    Literature over the past 10 years has provided conflicting views about the relative importance of precipitation symmetry and convective intensity for tropical cyclone intensification. While several modeling studies (Braun et al. 2006, Guimond et al. 2010, Molinari et al. 2013, Rogers et al. 2013, 2015) have favored intense deep convection, satellite-based composite studies, on the other hand, have offered a differing pathway towards tropical cyclone intensification emphasizing shallow to moderate precipitation (Zagrodnik and Jiang 2014, Tao and Jiang 2015, Alvey et al. 2015). This has left fundamental questions unanswered regarding the relationships between precipitation and TC intensity change: What are the dominant precipitation types, their spatial distributions, and the timing of these features with respect to intensification? And what causes precipitation to symmetrize and increase in the upshear quadrants? One potentially important process, the humidification of upshear quadrants, has been identified to occur nearly coincidental with increased precipitation symmetry prior to and during Edouard's (2014) intensification (Zawislak et al. 2016). While observations from the Global Hawk and P-3 provided important snapshots throughout the life cycle of Edouard (2014), numerical simulations complement and reveal, in more detail, the processes behind these relationships through filling an 48-hour airborne observational gap during a crucial period of intensification between 12-14 Sept. We use a high resolution, full physics ensemble of Edouard (2014) simulated by the Weather Research and Forecasting (WRF) model - Advanced Research WRF (ARW; Skamarock et al., 2008). We deem the quantification of azimuthal variations — with a focus on the shear-relative quadrants — as particularly important, especially early in intensification when thermodynamic and precipitation distributions tend to be more asymmetric. Using a water vapor budget and trajectories we examine whether

  15. Evaluating Microphysics in Cloud-Resolving Models using TRMM and Ground-based Precipitation Radar Observations

    Science.gov (United States)

    Krueger, S. K.; Zulauf, M. A.; Li, Y.; Zipser, E. J.

    2005-05-01

    Global satellite datasets such as those produced by ISCCP, ERBE, and CERES provide strong observational constraints on cloud radiative properties. Such observations have been widely used for model evaluation, tuning, and improvement. Cloud radiative properties depend primarily on small, non-precipitating cloud droplets and ice crystals, yet the dynamical, microphysical and radiative processes which produce these small particles often involve large, precipitating hydrometeors. There now exists a global dataset of tropical cloud system precipitation feature (PF) properties, collected by TRMM and produced by Steve Nesbitt, that provides additional observational constraints on cloud system properties. We are using the TRMM PF dataset to evaluate the precipitation microphysics of two simulations of deep, precipitating, convective cloud systems: one is a 29-day summertime, continental case (ARM Summer 1997 SCM IOP, at the Southern Great Plains site); the second is a tropical maritime case: the Kwajalein MCS of 11-12 August 1999 (part of a 52-day simulation). Both simulations employed the same bulk, three-ice category microphysical parameterization (Krueger et al. 1995). The ARM simulation was executed using the UCLA/Utah 2D CRM, while the KWAJEX simulation was produced using the 3D CSU CRM (SAM). The KWAJEX simulation described above is compared with both the actual radar data and the TRMM statistics. For the Kwajalein MCS of 11 to 12 August 1999, there are research radar data available for the lifetime of the system. This particular MCS was large in size and rained heavily, but it was weak to average in measures of convective intensity, against the 5-year TRMM sample of 108. For the Kwajalein MCS simulation, the 20 dBZ contour is at 15.7 km and the 40 dBZ contour at 14.5 km! Of all 108 MCSs observed by TRMM, the highest value for the 40 dBZ contour is 8 km. Clearly, the high reflectivity cores are off scale compared with observed cloud systems in this area. A similar

  16. Diurnal variation of summer precipitation over the Tibetan Plateau. A cloud-resolving simulation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jianyu; Zhang, Bing; Wang, Minghuan [China Meteorological Administration, Wuhan (China). Wuhan Inst. of Heavy Rain; Wang, Huijuan [Weather Modification Office of Hubei Province, Wuhan (China)

    2012-07-01

    In this study, the Weather Research and Forecasting model was used to simulate the diurnal variation in summer precipitation over the Tibetan Plateau (TP) at a cloudresolving scale. Compared with the TRMM, precipitation data shows that the model can well simulate the diurnal rainfall cycle with an overall late-afternoon maximum precipitation in the central TP and a nighttime maximum in the southern edge. The simulated diurnal variations in regional circulation and thermodynamics are in good correspondence with the precipitation diurnal cycles in the central and southern edge of TP, respectively. A possible mechanism responsible for the nocturnal precipitation maximum in the southern edge has been proposed, indicating the importance of the TP in regulating the regional circulation and precipitation. (orig.)

  17. Evaluation of Cloud-Resolving and Limited Area Model Intercomparison Simulations Using TWP-ICE Observations. Part 2 ; Precipitation Microphysics

    Science.gov (United States)

    Varble, Adam; Zipser, Edward J.; Fridland, Ann M.; Zhu, Ping; Ackerman, Andrew S.; Chaboureau, Jean-Pierre; Fan, Jiwen; Hill, Adrian; Shipway, Ben; Williams, Christopher

    2014-01-01

    Ten 3-D cloud-resolving model (CRM) simulations and four 3-D limited area model (LAM) simulations of an intense mesoscale convective system observed on 23-24 January 2006 during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) are compared with each other and with observations and retrievals from a scanning polarimetric radar, colocated UHF and VHF vertical profilers, and a Joss-Waldvogel disdrometer in an attempt to explain a low bias in simulated stratiform rainfall. Despite different forcing methodologies, similar precipitation microphysics errors appear in CRMs and LAMs with differences that depend on the details of the bulk microphysics scheme used. One-moment schemes produce too many small raindrops, which biases Doppler velocities low, but produces rainwater contents (RWCs) that are similar to observed. Two-moment rain schemes with a gamma shape parameter (mu) of 0 produce excessive size sorting, which leads to larger Doppler velocities than those produced in one-moment schemes but lower RWCs. Two-moment schemes also produce a convective median volume diameter distribution that is too broad relative to observations and, thus, may have issues balancing raindrop formation, collision-coalescence, and raindrop breakup. Assuming a mu of 2.5 rather than 0 for the raindrop size distribution improves one-moment scheme biases, and allowing mu to have values greater than 0 may improve excessive size sorting in two-moment schemes. Underpredicted stratiform rain rates are associated with underpredicted ice water contents at the melting level rather than excessive rain evaporation, in turn likely associated with convective detrainment that is too high in the troposphere and mesoscale circulations that are too weak. A limited domain size also prevents a large, well-developed stratiform region like the one observed from developing in CRMs, although LAMs also fail to produce such a region.

  18. The Microphysical Properties of Convective Precipitation Over the Tibetan Plateau by a Subkilometer Resolution Cloud-Resolving Simulation

    Science.gov (United States)

    Gao, Wenhua; Liu, Liping; Li, Jian; Lu, Chunsong

    2018-03-01

    The microphysical properties of convective precipitation over the Tibetan Plateau are unique because of the extremely high topography and special atmospheric conditions. In this study, the ground-based cloud radar and disdrometer observations as well as high-resolution Weather Research and Forecasting simulations with the Chinese Academy of Meteorological Sciences microphysics and four other microphysical schemes are used to investigate the microphysics and precipitation mechanisms of a convection event on 24 July 2014. The Weather Research and Forecasting-Chinese Academy of Meteorological Sciences simulation reasonably reproduces the spatial distribution of 24-hr accumulated rainfall, yet the temporal evolution of rain rate has a delay of 1-3 hr. The model reflectivity shares the common features with the cloud radar observations. The simulated raindrop size distributions demonstrate more of small- and large-size raindrops produced with the increase of rain rate, suggesting that changeable shape parameter should be used in size distribution. Results show that abundant supercooled water exists through condensation of water vapor above the freezing layer. The prevailing ice crystal microphysical processes are depositional growth and autoconversion of ice crystal to snow. The dominant source term of snow/graupel is riming of supercooled water. Sedimentation of graupel can play a vital role in the formation of precipitation, but melting of snow is rather small and quite different from that in other regions. Furthermore, water vapor budgets suggest that surface moisture flux be the principal source of water vapor and self-circulation of moisture happen at the beginning of convection, while total moisture flux convergence determine condensation and precipitation during the convective process over the Tibetan Plateau.

  19. Effects of Precipitation on Ocean Mixed-Layer Temperature and Salinity as Simulated in a 2-D Coupled Ocean-Cloud Resolving Atmosphere Model

    Science.gov (United States)

    Li, Xiaofan; Sui, C.-H.; Lau, K-M.; Adamec, D.

    1999-01-01

    A two-dimensional coupled ocean-cloud resolving atmosphere model is used to investigate possible roles of convective scale ocean disturbances induced by atmospheric precipitation on ocean mixed-layer heat and salt budgets. The model couples a cloud resolving model with an embedded mixed layer-ocean circulation model. Five experiment are performed under imposed large-scale atmospheric forcing in terms of vertical velocity derived from the TOGA COARE observations during a selected seven-day period. The dominant variability of mixed-layer temperature and salinity are simulated by the coupled model with imposed large-scale forcing. The mixed-layer temperatures in the coupled experiments with 1-D and 2-D ocean models show similar variations when salinity effects are not included. When salinity effects are included, however, differences in the domain-mean mixed-layer salinity and temperature between coupled experiments with 1-D and 2-D ocean models could be as large as 0.3 PSU and 0.4 C respectively. Without fresh water effects, the nocturnal heat loss over ocean surface causes deep mixed layers and weak cooling rates so that the nocturnal mixed-layer temperatures tend to be horizontally-uniform. The fresh water flux, however, causes shallow mixed layers over convective areas while the nocturnal heat loss causes deep mixed layer over convection-free areas so that the mixed-layer temperatures have large horizontal fluctuations. Furthermore, fresh water flux exhibits larger spatial fluctuations than surface heat flux because heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. As a result, mixed-layer salinities contribute more to the density differences than do mixed-layer temperatures.

  20. Evolution of Precipitation Structure During the November DYNAMO MJO Event: Cloud-Resolving Model Intercomparison and Cross Validation Using Radar Observations

    Science.gov (United States)

    Li, Xiaowen; Janiga, Matthew A.; Wang, Shuguang; Tao, Wei-Kuo; Rowe, Angela; Xu, Weixin; Liu, Chuntao; Matsui, Toshihisa; Zhang, Chidong

    2018-04-01

    Evolution of precipitation structures are simulated and compared with radar observations for the November Madden-Julian Oscillation (MJO) event during the DYNAmics of the MJO (DYNAMO) field campaign. Three ground-based, ship-borne, and spaceborne precipitation radars and three cloud-resolving models (CRMs) driven by observed large-scale forcing are used to study precipitation structures at different locations over the central equatorial Indian Ocean. Convective strength is represented by 0-dBZ echo-top heights, and convective organization by contiguous 17-dBZ areas. The multi-radar and multi-model framework allows for more stringent model validations. The emphasis is on testing models' ability to simulate subtle differences observed at different radar sites when the MJO event passed through. The results show that CRMs forced by site-specific large-scale forcing can reproduce not only common features in cloud populations but also subtle variations observed by different radars. The comparisons also revealed common deficiencies in CRM simulations where they underestimate radar echo-top heights for the strongest convection within large, organized precipitation features. Cross validations with multiple radars and models also enable quantitative comparisons in CRM sensitivity studies using different large-scale forcing, microphysical schemes and parameters, resolutions, and domain sizes. In terms of radar echo-top height temporal variations, many model sensitivity tests have better correlations than radar/model comparisons, indicating robustness in model performance on this aspect. It is further shown that well-validated model simulations could be used to constrain uncertainties in observed echo-top heights when the low-resolution surveillance scanning strategy is used.

  1. Projection of the change in future extremes over Japan using a cloud-resolving model: (2) Precipitation Extremes and the results of the NHM-1km experiments

    Science.gov (United States)

    Kanada, S.; Nakano, M.; Nakamura, M.; Hayashi, S.; Kato, T.; Kurihara, K.; Sasaki, H.; Uchiyama, T.; Aranami, K.; Honda, Y.; Kitoh, A.

    2008-12-01

    In order to study changes in the regional climate in the vicinity of Japan during the summer rainy season due to global warming, experiments by a semi-cloud resolving non-hydrostatic model with a horizontal resolution of 5km (NHM-5km) have been conducted from June to October by nesting within the results of the 10-year time-integrated experiments using a hydrostatic atmospheric general circulation model with a horizontal grid of 20 km (AGCM-20km: TL959L60) for the present and future up to the year 2100. A non-hydrostatic model developed by the Japan Meteorological Agency (JMA) (JMA-NHM; Saito et al. 2001, 2006) was adopted. Detailed descriptions of the NHM-5km are shown by the poster of Nakano et al. Our results show that rainy days over most of the Japanese Islands will decrease in June and July and increase in August and September in the future climate. Especially, remarkable increases in intense precipitations such as larger than 150 - 300 mm/day are projected from the present to future climate. The 90th percentiles of regional largest values among maximum daily precipitations (R-MDPs) grow 156 to 207 mm/day in the present and future climates, respectively. It is well-known that the horizontal distribution of precipitation, especially the heavy rainfall in the vicinity of Japan, much depends on the topography. Therefore, higher resolution experiments by a cloud-resolving model with a horizontal resolution of 1km (NHM-1km) are one-way nested within the results of NHM-5km. The basic frame and design of the NHM-1km is the same as those of the NHM-5km, but the topography is finer and no cumulus parameterization is used in the NHM-1km experiments. The NHM-1km, which treats the convection and cloud microphysics explicitly, can represent not only horizontal distributions of rainfall in detail but also the 3-dimensional structures of meso-beta-scale convective systems (MCSs). Because of the limitation of computation resources, only heavy rainfall events that rank in top

  2. A study of cloud microphysics and precipitation over the Tibetan Plateau by radar observations and cloud-resolving model simulations: Cloud Microphysics over Tibetan Plateau

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Wenhua [State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing China; Pacific Northwest National Laboratory, Richland Washington USA; Sui, Chung-Hsiung [Department of Atmospheric Sciences, National Taiwan University, Taipei Taiwan; Fan, Jiwen [Pacific Northwest National Laboratory, Richland Washington USA; Hu, Zhiqun [State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing China; Zhong, Lingzhi [State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing China

    2016-11-27

    Cloud microphysical properties and precipitation over the Tibetan Plateau (TP) are unique because of the high terrains, clean atmosphere, and sufficient water vapor. With dual-polarization precipitation radar and cloud radar measurements during the Third Tibetan Plateau Atmospheric Scientific Experiment (TIPEX-III), the simulated microphysics and precipitation by the Weather Research and Forecasting model (WRF) with the Chinese Academy of Meteorological Sciences (CAMS) microphysics and other microphysical schemes are investigated through a typical plateau rainfall event on 22 July 2014. Results show that the WRF-CAMS simulation reasonably reproduces the spatial distribution of 24-h accumulated precipitation, but has limitations in simulating time evolution of precipitation rates. The model-calculated polarimetric radar variables have biases as well, suggesting bias in modeled hydrometeor types. The raindrop sizes in convective region are larger than those in stratiform region indicated by the small intercept of raindrop size distribution in the former. The sensitivity experiments show that precipitation processes are sensitive to the changes of warm rain processes in condensation and nucleated droplet size (but less sensitive to evaporation process). Increasing droplet condensation produces the best area-averaged rain rate during weak convection period compared with the observation, suggesting a considerable bias in thermodynamics in the baseline simulation. Increasing the initial cloud droplet size causes the rain rate reduced by half, an opposite effect to that of increasing droplet condensation.

  3. Representation of Arctic mixed-phase clouds and the Wegener-Bergeron-Findeisen process in climate models: Perspectives from a cloud-resolving study

    Science.gov (United States)

    Fan, Jiwen; Ghan, Steven; Ovchinnikov, Mikhail; Liu, Xiaohong; Rasch, Philip J.; Korolev, Alexei

    2011-01-01

    Two types of Arctic mixed-phase clouds observed during the ISDAC and M-PACE field campaigns are simulated using a 3-dimensional cloud-resolving model (CRM) with size-resolved cloud microphysics. The modeled cloud properties agree reasonably well with aircraft measurements and surface-based retrievals. Cloud properties such as the probability density function (PDF) of vertical velocity (w), cloud liquid and ice, regimes of cloud particle growth, including the Wegener-Bergeron-Findeisen (WBF) process, and the relationships among properties/processes in mixed-phase clouds are examined to gain insights for improving their representation in General Circulation Models (GCMs). The PDF of the simulated w is well represented by a Gaussian function, validating, at least for arctic clouds, the subgrid treatment used in GCMs. The PDFs of liquid and ice water contents can be approximated by Gamma functions, and a Gaussian function can describe the total water distribution, but a fixed variance assumption should be avoided in both cases. The CRM results support the assumption frequently used in GCMs that mixed phase clouds maintain water vapor near liquid saturation. Thus, ice continues to grow throughout the stratiform cloud but the WBF process occurs in about 50% of cloud volume where liquid and ice co-exist, predominantly in downdrafts. In updrafts, liquid and ice particles grow simultaneously. The relationship between the ice depositional growth rate and cloud ice strongly depends on the capacitance of ice particles. The simplified size-independent capacitance of ice particles used in GCMs could lead to large deviations in ice depositional growth.

  4. Effects of sea surface temperature, cloud radiative and microphysical processes, and diurnal variations on rainfall in equilibrium cloud-resolving model simulations

    International Nuclear Information System (INIS)

    Jiang Zhe; Li Xiao-Fan; Zhou Yu-Shu; Gao Shou-Ting

    2012-01-01

    The effects of sea surface temperature (SST), cloud radiative and microphysical processes, and diurnal variations on rainfall statistics are documented with grid data from the two-dimensional equilibrium cloud-resolving model simulations. For a rain rate of higher than 3 mm·h −1 , water vapor convergence prevails. The rainfall amount decreases with the decrease of SST from 29 °C to 27 °C, the inclusion of diurnal variation of SST, or the exclusion of microphysical effects of ice clouds and radiative effects of water clouds, which are primarily associated with the decreases in water vapor convergence. However, the amount of rainfall increases with the increase of SST from 29 °C to 31 °C, the exclusion of diurnal variation of solar zenith angle, and the exclusion of the radiative effects of ice clouds, which are primarily related to increases in water vapor convergence. For a rain rate of less than 3 mm·h −1 , water vapor divergence prevails. Unlike rainfall statistics for rain rates of higher than 3 mm·h −1 , the decrease of SST from 29 °C to 27 °C and the exclusion of radiative effects of water clouds in the presence of radiative effects of ice clouds increase the rainfall amount, which corresponds to the suppression in water vapor divergence. The exclusion of microphysical effects of ice clouds decreases the amount of rainfall, which corresponds to the enhancement in water vapor divergence. The amount of rainfall is less sensitive to the increase of SST from 29 °C to 31 °C and to the radiative effects of water clouds in the absence of the radiative effects of ice clouds. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  5. Convective Systems Over the Japan Sea: Cloud-Resolving Model Simulations

    Science.gov (United States)

    Tao, Wei-Kuo; Yoshizaki, Masanori; Shie, Chung-Lin; Kato, Teryuki

    2002-01-01

    Wintertime observations of MCSs (Mesoscale Convective Systems) over the Sea of Japan - 2001 (WMO-01) were collected from January 12 to February 1, 2001. One of the major objectives is to better understand and forecast snow systems and accompanying disturbances and the associated key physical processes involved in the formation and development of these disturbances. Multiple observation platforms (e.g., upper-air soundings, Doppler radar, wind profilers, radiometers, etc.) during WMO-01 provided a first attempt at investigating the detailed characteristics of convective storms and air pattern changes associated with winter storms over the Sea of Japan region. WMO-01 also provided estimates of the apparent heat source (Q1) and apparent moisture sink (Q2). The vertical integrals of Q1 and Q2 are equal to the surface precipitation rates. The horizontal and vertical adjective components of Q1 and Q2 can be used as large-scale forcing for the Cloud Resolving Models (CRMs). The Goddard Cumulus Ensemble (GCE) model is a CRM (typically run with a 1-km grid size). The GCE model has sophisticated microphysics and allows explicit interactions between clouds, radiation, and surface processes. It will be used to understand and quantify precipitation processes associated with wintertime convective systems over the Sea of Japan (using data collected during the WMO-01). This is the first cloud-resolving model used to simulate precipitation processes in this particular region. The GCE model-simulated WMO-01 results will also be compared to other GCE model-simulated weather systems that developed during other field campaigns (i.e., South China Sea, west Pacific warm pool region, eastern Atlantic region and central USA).

  6. A Multi-scale Modeling System with Unified Physics to Study Precipitation Processes

    Science.gov (United States)

    Tao, W. K.

    2017-12-01

    In recent years, exponentially increasing computer power has extended Cloud Resolving Model (CRM) integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as 10,000 km in two-dimensions, and 1,000 x 1,000 km2 in three-dimensions. Cloud resolving models now provide statistical information useful for developing more realistic physically based parameterizations for climate models and numerical weather prediction models. It is also expected that NWP and mesoscale model can be run in grid size similar to cloud resolving model through nesting technique. Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (1) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), and (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF). The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, a review of developments and applications of the multi-scale modeling system will be presented. In particular, the results from using multi-scale modeling system to study the precipitation, processes and their sensitivity on model resolution and microphysics schemes will be presented. Also how to use of the multi-satellite simulator to improve precipitation processes will be discussed.

  7. Spectral cumulus parameterization based on cloud-resolving model

    Science.gov (United States)

    Baba, Yuya

    2018-02-01

    We have developed a spectral cumulus parameterization using a cloud-resolving model. This includes a new parameterization of the entrainment rate which was derived from analysis of the cloud properties obtained from the cloud-resolving model simulation and was valid for both shallow and deep convection. The new scheme was examined in a single-column model experiment and compared with the existing parameterization of Gregory (2001, Q J R Meteorol Soc 127:53-72) (GR scheme). The results showed that the GR scheme simulated more shallow and diluted convection than the new scheme. To further validate the physical performance of the parameterizations, Atmospheric Model Intercomparison Project (AMIP) experiments were performed, and the results were compared with reanalysis data. The new scheme performed better than the GR scheme in terms of mean state and variability of atmospheric circulation, i.e., the new scheme improved positive bias of precipitation in western Pacific region, and improved positive bias of outgoing shortwave radiation over the ocean. The new scheme also simulated better features of convectively coupled equatorial waves and Madden-Julian oscillation. These improvements were found to be derived from the modification of parameterization for the entrainment rate, i.e., the proposed parameterization suppressed excessive increase of entrainment, thus suppressing excessive increase of low-level clouds.

  8. Development of a Cloud Resolving Model for Heterogeneous Supercomputers

    Science.gov (United States)

    Sreepathi, S.; Norman, M. R.; Pal, A.; Hannah, W.; Ponder, C.

    2017-12-01

    A cloud resolving climate model is needed to reduce major systematic errors in climate simulations due to structural uncertainty in numerical treatments of convection - such as convective storm systems. This research describes the porting effort to enable SAM (System for Atmosphere Modeling) cloud resolving model on heterogeneous supercomputers using GPUs (Graphical Processing Units). We have isolated a standalone configuration of SAM that is targeted to be integrated into the DOE ACME (Accelerated Climate Modeling for Energy) Earth System model. We have identified key computational kernels from the model and offloaded them to a GPU using the OpenACC programming model. Furthermore, we are investigating various optimization strategies intended to enhance GPU utilization including loop fusion/fission, coalesced data access and loop refactoring to a higher abstraction level. We will present early performance results, lessons learned as well as optimization strategies. The computational platform used in this study is the Summitdev system, an early testbed that is one generation removed from Summit, the next leadership class supercomputer at Oak Ridge National Laboratory. The system contains 54 nodes wherein each node has 2 IBM POWER8 CPUs and 4 NVIDIA Tesla P100 GPUs. This work is part of a larger project, ACME-MMF component of the U.S. Department of Energy(DOE) Exascale Computing Project. The ACME-MMF approach addresses structural uncertainty in cloud processes by replacing traditional parameterizations with cloud resolving "superparameterization" within each grid cell of global climate model. Super-parameterization dramatically increases arithmetic intensity, making the MMF approach an ideal strategy to achieve good performance on emerging exascale computing architectures. The goal of the project is to integrate superparameterization into ACME, and explore its full potential to scientifically and computationally advance climate simulation and prediction.

  9. Using Multi-Scale Modeling Systems and Satellite Data to Study the Precipitation Processes

    Science.gov (United States)

    Tao, Wei-Kuo; Chern, J.; Lamg, S.; Matsui, T.; Shen, B.; Zeng, X.; Shi, R.

    2011-01-01

    In recent years, exponentially increasing computer power has extended Cloud Resolving Model (CRM) integrations from hours to months, the number of computational grid points from less than a thousand to close to ten million. Three-dimensional models are now more prevalent. Much attention is devoted to precipitating cloud systems where the crucial 1-km scales are resolved in horizontal domains as large as 10,000 km in two-dimensions, and 1,000 x 1,000 km2 in three-dimensions. Cloud resolving models now provide statistical information useful for developing more realistic physically based parameterizations for climate models and numerical weather prediction models. It is also expected that NWP and mesoscale model can be run in grid size similar to cloud resolving model through nesting technique. Recently, a multi-scale modeling system with unified physics was developed at NASA Goddard. It consists of (l) a cloud-resolving model (Goddard Cumulus Ensemble model, GCE model), (2) a regional scale model (a NASA unified weather research and forecast, WRF), (3) a coupled CRM and global model (Goddard Multi-scale Modeling Framework, MMF), and (4) a land modeling system. The same microphysical processes, long and short wave radiative transfer and land processes and the explicit cloud-radiation, and cloud-land surface interactive processes are applied in this multi-scale modeling system. This modeling system has been coupled with a multi-satellite simulator to use NASA high-resolution satellite data to identify the strengths and weaknesses of cloud and precipitation processes simulated by the model. In this talk, the recent developments and applications of the multi-scale modeling system will be presented. In particular, the results from using multi-scale modeling system to study the precipitating systems and hurricanes/typhoons will be presented. The high-resolution spatial and temporal visualization will be utilized to show the evolution of precipitation processes. Also how to

  10. Numerical simulations of altocumulus with a cloud resolving model

    Energy Technology Data Exchange (ETDEWEB)

    Liu, S.; Krueger, S.K. [Univ. of Utah, Salt Lake City, UT (United States)

    1996-04-01

    Altocumulus and altostratus clouds together cover approximately 22% of the earth`s surface. They play an important role in the earth`s energy budget through their effect on solar and infrared radiation. However, there has been little altocumulus cloud investigation by either modelers or observational programs. Starr and Cox (SC) (1985a,b) simulated an altostratus case as part of the same study in which they modeled a thin layer of cirrus. Although this calculation was originally described as representing altostratus, it probably better represents altocumulus stratiformis. In this paper, we simulate altocumulus cloud with a cloud resolving model (CRM). We simply describe the CRM first. We calculate the same middle-level cloud case as SC to compare our results with theirs. We will look at the role of cloud-scale processes in response to large-scale forcing. We will also discuss radiative effects by simulating diurnal and nocturnal cases. Finally, we discuss the utility of a 1D model by comparing 1D simulations and 2D simulations.

  11. Coupled fvGCM-GCE Modeling System, 3D Cloud-Resolving Model and Cloud Library

    Science.gov (United States)

    Tao, Wei-Kuo

    2005-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud- resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and more sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. A seed fund is available at NASA Goddard to build a MMF based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM). A prototype MMF in being developed and production runs will be conducted at the beginning of 2005. In this talk, I will present: (1) A brief review on GCE model and its applications on precipitation processes, ( 2 ) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), (3) A cloud library generated by Goddard MMF, and 3D GCE model, and (4) A brief discussion on the GCE model on developing a global cloud simulator.

  12. Strategy for long-term 3D cloud-resolving simulations over the ARM SGP site and preliminary results

    Science.gov (United States)

    Lin, W.; Liu, Y.; Song, H.; Endo, S.

    2011-12-01

    Parametric representations of cloud/precipitation processes continue having to be adopted in climate simulations with increasingly higher spatial resolution or with emerging adaptive mesh framework; and it is only becoming more critical that such parameterizations have to be scale aware. Continuous cloud measurements at DOE's ARM sites have provided a strong observational basis for novel cloud parameterization research at various scales. Despite significant progress in our observational ability, there are important cloud-scale physical and dynamical quantities that are either not currently observable or insufficiently sampled. To complement the long-term ARM measurements, we have explored an optimal strategy to carry out long-term 3-D cloud-resolving simulations over the ARM SGP site using Weather Research and Forecasting (WRF) model with multi-domain nesting. The factors that are considered to have important influences on the simulated cloud fields include domain size, spatial resolution, model top, forcing data set, model physics and the growth of model errors. The hydrometeor advection that may play a significant role in hydrological process within the observational domain but is often lacking, and the limitations due to the constraint of domain-wide uniform forcing in conventional cloud system-resolving model simulations, are at least partly accounted for in our approach. Conventional and probabilistic verification approaches are employed first for selected cases to optimize the model's capability of faithfully reproducing the observed mean and statistical distributions of cloud-scale quantities. This then forms the basis of our setup for long-term cloud-resolving simulations over the ARM SGP site. The model results will facilitate parameterization research, as well as understanding and dissecting parameterization deficiencies in climate models.

  13. Forecasting Lightning Threat using Cloud-Resolving Model Simulations

    Science.gov (United States)

    McCaul, Eugene W., Jr.; Goodman, Steven J.; LaCasse, Katherine M.; Cecil, Daniel J.

    2008-01-01

    Two new approaches are proposed and developed for making time and space dependent, quantitative short-term forecasts of lightning threat, and a blend of these approaches is devised that capitalizes on the strengths of each. The new methods are distinctive in that they are based entirely on the ice-phase hydrometeor fields generated by regional cloud-resolving numerical simulations, such as those produced by the WRF model. These methods are justified by established observational evidence linking aspects of the precipitating ice hydrometeor fields to total flash rates. The methods are straightforward and easy to implement, and offer an effective near-term alternative to the incorporation of complex and costly cloud electrification schemes into numerical models. One method is based on upward fluxes of precipitating ice hydrometeors in the mixed phase region at the-15 C level, while the second method is based on the vertically integrated amounts of ice hydrometeors in each model grid column. Each method can be calibrated by comparing domain-wide statistics of the peak values of simulated flash rate proxy fields against domain-wide peak total lightning flash rate density data from observations. Tests show that the first method is able to capture much of the temporal variability of the lightning threat, while the second method does a better job of depicting the areal coverage of the threat. Our blended solution is designed to retain most of the temporal sensitivity of the first method, while adding the improved spatial coverage of the second. Exploratory tests for selected North Alabama cases show that, because WRF can distinguish the general character of most convective events, our methods show promise as a means of generating quantitatively realistic fields of lightning threat. However, because the models tend to have more difficulty in predicting the instantaneous placement of storms, forecasts of the detailed location of the lightning threat based on single

  14. Evaluating Cloud and Precipitation Processes in Numerical Models using Current and Potential Future Satellite Missions

    Science.gov (United States)

    van den Heever, S. C.; Tao, W. K.; Skofronick Jackson, G.; Tanelli, S.; L'Ecuyer, T. S.; Petersen, W. A.; Kummerow, C. D.

    2015-12-01

    Cloud, aerosol and precipitation processes play a fundamental role in the water and energy cycle. It is critical to accurately represent these microphysical processes in numerical models if we are to better predict cloud and precipitation properties on weather through climate timescales. Much has been learned about cloud properties and precipitation characteristics from NASA satellite missions such as TRMM, CloudSat, and more recently GPM. Furthermore, data from these missions have been successfully utilized in evaluating the microphysical schemes in cloud-resolving models (CRMs) and global models. However, there are still many uncertainties associated with these microphysics schemes. These uncertainties can be attributed, at least in part, to the fact that microphysical processes cannot be directly observed or measured, but instead have to be inferred from those cloud properties that can be measured. Evaluation of microphysical parameterizations are becoming increasingly important as enhanced computational capabilities are facilitating the use of more sophisticated schemes in CRMs, and as future global models are being run on what has traditionally been regarded as cloud-resolving scales using CRM microphysical schemes. In this talk we will demonstrate how TRMM, CloudSat and GPM data have been used to evaluate different aspects of current CRM microphysical schemes, providing examples of where these approaches have been successful. We will also highlight CRM microphysical processes that have not been well evaluated and suggest approaches for addressing such issues. Finally, we will introduce a potential NASA satellite mission, the Cloud and Precipitation Processes Mission (CAPPM), which would facilitate the development and evaluation of different microphysical-dynamical feedbacks in numerical models.

  15. Precipitation process for supernate decontamination

    International Nuclear Information System (INIS)

    Lee, L.M.; Kilpatrick, L.L.

    1982-11-01

    A precipitation and adsorption process has been developed to remove cesium, strontium, and plutonium from water-soluble, high-level radioactive waste. An existing waste tank serves as the reaction vessel and the process begins with the addition of a solution of sodium tetraphenylborate and a slurry of sodium titanate to the contained waste salt solution. Sodium tetraphenylborate precipitates the cesium and sodium titanate adsorbs the strontium and plutonium. The precipitate/adsorbate is then separated from the decontaminated salt solution by crossflow filtration. This new process offers significant capital savings over an earlier ion exchange process for salt decontamination. Chemical and small-scale engineering studies with actual waste are reported. The effect of many variables on the decontamination factors and filter performance are defined

  16. Sensitivity of tropical convection in cloud-resolving WRF simulations to model physics and forcing procedures

    Science.gov (United States)

    Endo, S.; Lin, W.; Jackson, R. C.; Collis, S. M.; Vogelmann, A. M.; Wang, D.; Oue, M.; Kollias, P.

    2017-12-01

    Tropical convection is one of the main drivers of the climate system and recognized as a major source of uncertainty in climate models. High-resolution modeling is performed with a focus on the deep convection cases during the active monsoon period of the TWP-ICE field campaign to explore ways to improve the fidelity of convection permitting tropical simulations. Cloud resolving model (CRM) simulations are performed with WRF modified to apply flexible configurations for LES/CRM simulations. We have enhanced the capability of the forcing module to test different implementations of large-scale vertical advective forcing, including a function for optional use of large-scale thermodynamic profiles and a function for the condensate advection. The baseline 3D CRM configurations are, following Fridlind et al. (2012), driven by observationally-constrained ARM forcing and tested with diagnosed surface fluxes and fixed sea-surface temperature and prescribed aerosol size distributions. After the spin-up period, the simulations follow the observed precipitation peaks associated with the passages of precipitation systems. Preliminary analysis shows that the simulation is generally not sensitive to the treatment of the large-scale vertical advection of heat and moisture, while more noticeable changes in the peak precipitation rate are produced when thermodynamic profiles above the boundary layer were nudged to the reference profiles from the forcing dataset. The presentation will explore comparisons with observationally-based metrics associated with convective characteristics and examine the model performance with a focus on model physics, doubly-periodic vs. nested configurations, and different forcing procedures/sources. A radar simulator will be used to understand possible uncertainties in radar-based retrievals of convection properties. Fridlind, A. M., et al. (2012), A comparison of TWP-ICE observational data with cloud-resolving model results, J. Geophys. Res., 117, D05204

  17. A Scalable Cloud Library Empowering Big Data Management, Diagnosis, and Visualization of Cloud-Resolving Models

    Science.gov (United States)

    Zhou, S.; Tao, W. K.; Li, X.; Matsui, T.; Sun, X. H.; Yang, X.

    2015-12-01

    A cloud-resolving model (CRM) is an atmospheric numerical model that can numerically resolve clouds and cloud systems at 0.25~5km horizontal grid spacings. The main advantage of the CRM is that it can allow explicit interactive processes between microphysics, radiation, turbulence, surface, and aerosols without subgrid cloud fraction, overlapping and convective parameterization. Because of their fine resolution and complex physical processes, it is challenging for the CRM community to i) visualize/inter-compare CRM simulations, ii) diagnose key processes for cloud-precipitation formation and intensity, and iii) evaluate against NASA's field campaign data and L1/L2 satellite data products due to large data volume (~10TB) and complexity of CRM's physical processes. We have been building the Super Cloud Library (SCL) upon a Hadoop framework, capable of CRM database management, distribution, visualization, subsetting, and evaluation in a scalable way. The current SCL capability includes (1) A SCL data model enables various CRM simulation outputs in NetCDF, including the NASA-Unified Weather Research and Forecasting (NU-WRF) and Goddard Cumulus Ensemble (GCE) model, to be accessed and processed by Hadoop, (2) A parallel NetCDF-to-CSV converter supports NU-WRF and GCE model outputs, (3) A technique visualizes Hadoop-resident data with IDL, (4) A technique subsets Hadoop-resident data, compliant to the SCL data model, with HIVE or Impala via HUE's Web interface, (5) A prototype enables a Hadoop MapReduce application to dynamically access and process data residing in a parallel file system, PVFS2 or CephFS, where high performance computing (HPC) simulation outputs such as NU-WRF's and GCE's are located. We are testing Apache Spark to speed up SCL data processing and analysis.With the SCL capabilities, SCL users can conduct large-domain on-demand tasks without downloading voluminous CRM datasets and various observations from NASA Field Campaigns and Satellite data to a

  18. Precipitation processes in implanted materials

    International Nuclear Information System (INIS)

    Borders, J.A.

    1978-01-01

    Ion implantation is a nonequilibrium process. It is possible to implant materials with impurities to concentration levels which exceed the solid solubilities. The return of the system to thermodynamic equilibrium is often accomplished by precipitation of the implanted species or a compound involving atoms of both the host and the implanted species. This may involve long time scales when taking place at room temperature or it may take place during the implantation

  19. IO strategies and data services for petascale data sets from a global cloud resolving model

    International Nuclear Information System (INIS)

    Schuchardt, K L; Palmer, B J; Daily, J A; Elsethagen, T O; Koontz, A S

    2007-01-01

    Global cloud resolving models at resolutions of 4km or less create significant challenges for simulation output, data storage, data management, and post-simulation analysis and visualization. To support efficient model output as well as data analysis, new methods for IO and data organization must be evaluated. The model we are supporting, the Global Cloud Resolving Model being developed at Colorado State University, uses a geodesic grid. The non-monotonic nature of the grid's coordinate variables requires enhancements to existing data processing tools and community standards for describing and manipulating grids. The resolution, size and extent of the data suggest the need for parallel analysis tools and allow for the possibility of new techniques in data mining, filtering and comparison to observations. We describe the challenges posed by various aspects of data generation, management, and analysis, our work exploring IO strategies for the model, and a preliminary architecture, web portal, and tool enhancements which, when complete, will enable broad community access to the data sets in familiar ways to the community

  20. A Coupled fcGCM-GCE Modeling System: A 3D Cloud Resolving Model and a Regional Scale Model

    Science.gov (United States)

    Tao, Wei-Kuo

    2005-01-01

    Recent GEWEX Cloud System Study (GCSS) model comparison projects have indicated that cloud-resolving models (CRMs) agree with observations better than traditional single-column models in simulating various types of clouds and cloud systems from different geographic locations. Current and future NASA satellite programs can provide cloud, precipitation, aerosol and other data at very fine spatial and temporal scales. It requires a coupled global circulation model (GCM) and cloud-scale model (termed a super-parameterization or multi-scale modeling framework, MMF) to use these satellite data to improve the understanding of the physical processes that are responsible for the variation in global and regional climate and hydrological systems. The use of a GCM will enable global coverage, and the use of a CRM will allow for better and ore sophisticated physical parameterization. NASA satellite and field campaign cloud related datasets can provide initial conditions as well as validation for both the MMF and CRMs. The Goddard MMF is based on the 2D Goddard Cumulus Ensemble (GCE) model and the Goddard finite volume general circulation model (fvGCM), and it has started production runs with two years results (1998 and 1999). Also, at Goddard, we have implemented several Goddard microphysical schemes (21CE, several 31CE), Goddard radiation (including explicity calculated cloud optical properties), and Goddard Land Information (LIS, that includes the CLM and NOAH land surface models) into a next generation regional scale model, WRF. In this talk, I will present: (1) A Brief review on GCE model and its applications on precipitation processes (microphysical and land processes), (2) The Goddard MMF and the major difference between two existing MMFs (CSU MMF and Goddard MMF), and preliminary results (the comparison with traditional GCMs), (3) A discussion on the Goddard WRF version (its developments and applications), and (4) The characteristics of the four-dimensional cloud data

  1. Cloud-resolving model intercomparison of an MC3E squall line case: Part I-Convective updrafts: CRM Intercomparison of a Squall Line

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jiwen [Pacific Northwest National Laboratory, Richland Washington USA; Han, Bin [Pacific Northwest National Laboratory, Richland Washington USA; School of Atmospheric Sciences, Nanjing University, Nanjing China; Varble, Adam [Department of Atmospheric Sciences, University of Utah, Salt Lake City Utah USA; Morrison, Hugh [National Center for Atmospheric Research, Boulder Colorado USA; North, Kirk [Department of Atmospheric and Oceanic Sciences, McGill University, Montreal Quebec USA; Kollias, Pavlos [Department of Atmospheric and Oceanic Sciences, McGill University, Montreal Quebec USA; School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook New York USA; Chen, Baojun [School of Atmospheric Sciences, Nanjing University, Nanjing China; Dong, Xiquan [Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson Arizona USA; Giangrande, Scott E. [Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton New York USA; Khain, Alexander [The Institute of the Earth Science, The Hebrew University of Jerusalem, Jerusalem Israel; Lin, Yun [Department of Atmospheric Sciences, Texas A& M University, College Station Texas USA; Mansell, Edward [NOAA/OAR/National Severe Storms Laboratory, Norman Oklahoma USA; Milbrandt, Jason A. [Meteorological Research Division, Environment and Climate Change Canada, Dorval Canada; Stenz, Ronald [Department of Atmospheric Sciences, University of North Dakota, Grand Forks North Dakota USA; Thompson, Gregory [National Center for Atmospheric Research, Boulder Colorado USA; Wang, Yuan [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena California USA

    2017-09-06

    A constrained model intercomparison study of a mid-latitude mesoscale squall line is performed using the Weather Research & Forecasting (WRF) model at 1-km horizontal grid spacing with eight cloud microphysics schemes, to understand specific processes that lead to the large spread of simulated cloud and precipitation at cloud-resolving scales, with a focus of this paper on convective cores. Various observational data are employed to evaluate the baseline simulations. All simulations tend to produce a wider convective area than observed, but a much narrower stratiform area, with most bulk schemes overpredicting radar reflectivity. The magnitudes of the virtual potential temperature drop, pressure rise, and the peak wind speed associated with the passage of the gust front are significantly smaller compared with the observations, suggesting simulated cool pools are weaker. Simulations also overestimate the vertical velocity and Ze in convective cores as compared with observational retrievals. The modeled updraft velocity and precipitation have a significant spread across the eight schemes even in this strongly dynamically-driven system. The spread of updraft velocity is attributed to the combined effects of the low-level perturbation pressure gradient determined by cold pool intensity and buoyancy that is not necessarily well correlated to differences in latent heating among the simulations. Variability of updraft velocity between schemes is also related to differences in ice-related parameterizations, whereas precipitation variability increases in no-ice simulations because of scheme differences in collision-coalescence parameterizations.

  2. Cloud-Resolving Model Simulations of Aerosol-Cloud Interactions Triggered by Strong Aerosol Emissions in the Arctic

    Science.gov (United States)

    Wang, H.; Kravitz, B.; Rasch, P. J.; Morrison, H.; Solomon, A.

    2014-12-01

    Previous process-oriented modeling studies have highlighted the dependence of effectiveness of cloud brightening by aerosols on cloud regimes in warm marine boundary layer. Cloud microphysical processes in clouds that contain ice, and hence the mechanisms that drive aerosol-cloud interactions, are more complicated than in warm clouds. Interactions between ice particles and liquid drops add additional levels of complexity to aerosol effects. A cloud-resolving model is used to study aerosol-cloud interactions in the Arctic triggered by strong aerosol emissions, through either geoengineering injection or concentrated sources such as shipping and fires. An updated cloud microphysical scheme with prognostic aerosol and cloud particle numbers is employed. Model simulations are performed in pure super-cooled liquid and mixed-phase clouds, separately, with or without an injection of aerosols into either a clean or a more polluted Arctic boundary layer. Vertical mixing and cloud scavenging of particles injected from the surface is still quite efficient in the less turbulent cold environment. Overall, the injection of aerosols into the Arctic boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. The pure liquid clouds are more susceptible to the increase in aerosol number concentration than the mixed-phase clouds. Rain production processes are more effectively suppressed by aerosol injection, whereas ice precipitation (snow) is affected less; thus the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. Aerosol injection into a clean boundary layer results in a greater cloud albedo increase than injection into a polluted one, consistent with current knowledge about aerosol-cloud interactions. Unlike previous studies investigating warm clouds, the impact of dynamical feedback due to precipitation changes is small. According to these results, which are dependent upon the representation of ice nucleation

  3. Continuous precipitation process of plutonium salts

    International Nuclear Information System (INIS)

    Richard, P.

    1967-03-01

    This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [fr

  4. Retrieving latent heating vertical structure from cloud and precipitation Profiles—Part I: Warm rain processes

    International Nuclear Information System (INIS)

    Min, Qilong; Li, Rui; Wu, Xiaoqing; Fu, Yunfei

    2013-01-01

    An exploratory study on physical based latent heat (LH) retrieval algorithm is conducted by parameterizing the physical linkages of hydrometeor profiles of cloud and precipitation to the major processes related to the phase change of atmospheric water. Specifically, rain events are segregated into three rain types: warm, convective, and stratiform, based on their dynamical and thermodynamical characteristics. As the first of the series, only the warm rain LH algorithm is presented and evaluated here. The major microphysical processes of condensation and evaporation for warm rain are parameterized through traditional rain growth theory, with the aid of Cloud Resolving Model (CRM) simulations. The evaluation or the self-consistency tests indicate that the physical based retrievals capture the fundamental LH processes associated with the warm rain life cycle. There is no significant systematic bias in terms of convection strength, illustrated by the month-long CRM simulation as the mesoscale convective systems (MCSs) experience from initial, mature, to decay stages. The overall monthly-mean LH comparison showed that the total LH, as well as condensation heating and evaporation cooling components, agree with the CRM simulation. -- Highlights: ► An exploratory study on physics-based warm rain latent heat retrieval algorithm. ► Utilize the full information of the vertical structures of cloud and rainfall. ► Directly link water mass measurements to latent heat at instantaneous pixel level. ► Applicable at various stages of cloud system life cycle

  5. The Relationship Between Latent Heating, Vertical Velocity, and Precipitation Processes: the Impact of Aerosols on Precipitation in Organized Deep Convective Systems

    Science.gov (United States)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-01-01

    A high-resolution, two-dimensional cloud-resolving model with spectral-bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low-level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity-governing equation shows that temperature buoyancy can enhance updraftsdowndrafts in the middlelower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF-temperature buoyancy forcing. The balance among these terms determines the intensity of convection.

  6. Scale-up of precipitation processes

    OpenAIRE

    Zauner, R.

    1999-01-01

    This thesis concerns the scale-up of precipitation processes aimed at predicting product particle characteristics. Although precipitation is widely used in the chemical and pharmaceutical industry, successful scale-up is difficult due to the absence of a validated methodology. It is found that none of the conventional scale-up criteria reported in the literature (equal power input per unit mass, equal tip speed, equal stirring rate) is capable of predicting the experimentally o...

  7. IMPROVED PROCESS OF PLUTONIUM CARRIER PRECIPITATION

    Science.gov (United States)

    Faris, B.F.

    1959-06-30

    This patent relates to an improvement in the bismuth phosphate process for separating and recovering plutonium from neutron irradiated uranium, resulting in improved decontamination even without the use of scavenging precipitates in the by-product precipitation step and subsequently more complete recovery of the plutonium in the product precipitation step. This improvement is achieved by addition of fluomolybdic acid, or a water soluble fluomolybdate, such as the ammonium, sodium, or potassium salt thereof, to the aqueous nitric acid solution containing tetravalent plutonium ions and contaminating fission products, so as to establish a fluomolybdate ion concentration of about 0.05 M. The solution is then treated to form the bismuth phosphate plutonium carrying precipitate.

  8. Global Precipitation Responses to Land Hydrological Processes

    Science.gov (United States)

    Lo, M.; Famiglietti, J. S.

    2012-12-01

    Several studies have established that soil moisture increases after adding a groundwater component in land surface models due to the additional supply of subsurface water. However, impacts of groundwater on the spatial-temporal variability of precipitation have received little attention. Through the coupled groundwater-land-atmosphere model (NCAR Community Atmosphere Model + Community Land Model) simulations, this study explores how groundwater representation in the model alters the precipitation spatiotemporal distributions. Results indicate that the effect of groundwater on the amount of precipitation is not globally homogeneous. Lower tropospheric water vapor increases due to the presence of groundwater in the model. The increased water vapor destabilizes the atmosphere and enhances the vertical upward velocity and precipitation in tropical convective regions. Precipitation, therefore, is inhibited in the descending branch of convection. As a result, an asymmetric dipole is produced over tropical land regions along the equator during the summer. This is analogous to the "rich-get-richer" mechanism proposed by previous studies. Moreover, groundwater also increased short-term (seasonal) and long-term (interannual) memory of precipitation for some regions with suitable groundwater table depth and found to be a function of water table depth. Based on the spatial distributions of the one-month-lag autocorrelation coefficients as well as Hurst coefficients, air-land interaction can occur from short (several months) to long (several years) time scales. This study indicates the importance of land hydrological processes in the climate system and the necessity of including the subsurface processes in the global climate models.

  9. Forecasting Lightning Threat using Cloud-resolving Model Simulations

    Science.gov (United States)

    McCaul, E. W., Jr.; Goodman, S. J.; LaCasse, K. M.; Cecil, D. J.

    2009-01-01

    As numerical forecasts capable of resolving individual convective clouds become more common, it is of interest to see if quantitative forecasts of lightning flash rate density are possible, based on fields computed by the numerical model. Previous observational research has shown robust relationships between observed lightning flash rates and inferred updraft and large precipitation ice fields in the mixed phase regions of storms, and that these relationships might allow simulated fields to serve as proxies for lightning flash rate density. It is shown in this paper that two simple proxy fields do indeed provide reasonable and cost-effective bases for creating time-evolving maps of predicted lightning flash rate density, judging from a series of diverse simulation case study events in North Alabama for which Lightning Mapping Array data provide ground truth. One method is based on the product of upward velocity and the mixing ratio of precipitating ice hydrometeors, modeled as graupel only, in the mixed phase region of storms at the -15\\dgc\\ level, while the second method is based on the vertically integrated amounts of ice hydrometeors in each model grid column. Each method can be calibrated by comparing domainwide statistics of the peak values of simulated flash rate proxy fields against domainwide peak total lightning flash rate density data from observations. Tests show that the first method is able to capture much of the temporal variability of the lightning threat, while the second method does a better job of depicting the areal coverage of the threat. A blended solution is designed to retain most of the temporal sensitivity of the first method, while adding the improved spatial coverage of the second. Weather Research and Forecast Model simulations of selected North Alabama cases show that this model can distinguish the general character and intensity of most convective events, and that the proposed methods show promise as a means of generating

  10. Defense waste processing facility precipitate hydrolysis process

    International Nuclear Information System (INIS)

    Doherty, J.P.; Eibling, R.E.; Marek, J.C.

    1986-03-01

    Sodium tetraphenylborate and sodium titanate are used to assist in the concentration of soluble radionuclide in the Savannah River Plant's high-level waste. In the Defense Waste Processing Facility, concentrated tetraphenylborate/sodium titanate slurry containing cesium-137, strontium-90 and traces of plutonium from the waste tank farm is hydrolyzed in the Salt Processing Cell forming organic and aqueous phases. The two phases are then separated and the organic phase is decontaminated for incineration outside the DWPF building. The aqueous phase, containing the radionuclides and less than 10% of the original organic, is blended with the insoluble radionuclides in the high-level waste sludge and is fed to the glass melter for vitrification into borosilicate glass. During the Savannah River Laboratory's development of this process, copper (II) was found to act as a catalyst during the hydrolysis reactions, which improved the organic removal and simplified the design of the reactor

  11. A Numerical Study of Vortex and Precipitating Cloud Merging in Middle Latitudes

    Institute of Scientific and Technical Information of China (English)

    PING Fan; LUO Zhe-Xian; JU Jian-Hua

    2006-01-01

    @@ We mainly focus on the study of precipitating cloud merging associated with vortex merging. The vortex and precipitating cloud merging are simulated by the cloud resolving model from 0000 21 to 1800 23 July 2003. The results show that the model well simulates vortex circulation associated with precipitating clouds. It is also proven that the vortex merging follows the precipitating cloud merging although vortices show the spatial and temporal differences. The convection vorticity vector is introduced to describe the merging processes. Two merging cases are identified during the 42-h simulation and are studied.

  12. Hanford phosphate precipitation filtration process evaluation

    International Nuclear Information System (INIS)

    Walker, B.W.; McCabe, D.J.

    1997-01-01

    The purpose of this filter study was to evaluate cross-flow filtration as effective solid-liquid separation technology for treating Hanford wastes, outline operating conditions for equipment, examine the expected filter flow rates, and determine proper cleaning. A proposed Hanford waste pre-treatment process uses sodium hydroxide at high temperature to remove aluminum from sludge. This process also dissolves phosphates. Upon cooling to 40 degrees centigrade the phosphates form a Na7(PO4)2F9H2O precipitate which must be removed prior to further treatment. Filter studies were conducted with a phosphate slurry simulant to evaluate whether 0.5 micron cross-flow sintered metal Mott filters can separate the phosphate precipitate from the wash solutions. The simulant was recirculated through the filters at room temperature and filtration performance data was collected

  13. Development of Spaceborne Radar Simulator by NICT and JAXA using JMA Cloud-resolving Model

    Science.gov (United States)

    Kubota, T.; Eito, H.; Aonashi, K.; Hashimoto, A.; Iguchi, T.; Hanado, H.; Shimizu, S.; Yoshida, N.; Oki, R.

    2009-12-01

    We are developing synthetic spaceborne radar data toward a simulation of the Dual-frequency Precipitation Radar (DPR) aboard the Global Precipitation Measurement (GPM) core-satellite. Our purposes are a production of test-bed data for higher level DPR algorithm developers, in addition to a diagnosis of a cloud resolving model (CRM). To make the synthetic data, we utilize the CRM by the Japan Meteorological Agency (JMA-NHM) (Ikawa and Saito 1991, Saito et al. 2006, 2007), and the spaceborne radar simulation algorithm by the National Institute of Information and Communications Technology (NICT) and the Japan Aerospace Exploration Agency (JAXA) named as the Integrated Satellite Observation Simulator for Radar (ISOSIM-Radar). The ISOSIM-Radar simulates received power data in a field of view of the spaceborne radar with consideration to a scan angle of the radar (Oouchi et al. 2002, Kubota et al. 2009). The received power data are computed with gaseous and hydrometeor attenuations taken into account. The backscattering and extinction coefficients are calculated assuming the Mie approximation for all species. The dielectric constants for solid particles are computed by the Maxwell-Garnett model (Bohren and Battan 1982). Drop size distributions are treated in accordance with those of the JMA-NHM. We assume a spherical sea surface, a Gaussian antenna pattern, and 49 antenna beam directions for scan angles from -17 to 17 deg. in the PR. In this study, we report the diagnosis of the JMA-NHM with reference to the TRMM Precipitation Radar (PR) and CloudSat Cloud Profiling Radar (CPR) using the ISOSIM-Radar from the view of comparisons in cloud microphysics schemes of the JMA-NHM. We tested three kinds of explicit bulk microphysics schemes based on Lin et al. (1983), that is, three-ice 1-moment scheme, three-ice 2-moment scheme (Eito and Aonashi 2009), and newly developed four-ice full 2-moment scheme (Hashimoto 2008). The hydrometeor species considered here are rain, graupel

  14. Convective and Stratiform Precipitation Processes and their Relationship to Latent Heating

    Science.gov (United States)

    Tao, Wei-Kuo; Lang, Steve; Zeng, Xiping; Shige, Shoichi; Takayabu, Yukari

    2009-01-01

    The global hydrological cycle is central to the Earth's climate system, with rainfall and the physics of its formation acting as the key links in the cycle. Two-thirds of global rainfall occurs in the Tropics. Associated with this rainfall is a vast amount of heat, which is known as latent heat. It arises mainly due to the phase change of water vapor condensing into liquid droplets; three-fourths of the total heat energy available to the Earth's atmosphere comes from tropical rainfall. In addition, fresh water provided by tropical rainfall and its variability exerts a large impact upon the structure and motions of the upper ocean layer. An improved convective -stratiform heating (CSH) algorithm has been developed to obtain the 3D structure of cloud heating over the Tropics based on two sources of information: 1) rainfall information, namely its amount and the fraction due to light rain intensity, observed directly from the Precipitation Radar (PR) on board the TRMM satellite and 2) synthetic cloud physics information obtained from cloud-resolving model (CRM) simulations of cloud systems. The cloud simulations provide details on cloud processes, specifically latent heating, eddy heat flux convergence and radiative heating/cooling, that. are not directly observable by satellite. The new CSH algorithm-derived heating has a noticeably different heating structure over both ocean and land regions compared to the previous CSH algorithm. One of the major differences between new and old algorithms is that the level of maximum cloud heating occurs 1 to 1.5 km lower in the atmosphere in the new algorithm. This can effect the structure of the implied air currents associated with the general circulation of the atmosphere in the Tropics. The new CSH algorithm will be used provide retrieved heating data to other heating algorithms to supplement their performance.

  15. Retrieving latent heating vertical structure from cloud and precipitation profiles—Part II: Deep convective and stratiform rain processes

    International Nuclear Information System (INIS)

    Li, Rui; Min, Qilong; Wu, Xiaoqing; Fu, Yunfei

    2013-01-01

    An exploratory study on physical based latent heat (LH) retrieval algorithm is conducted by parameterizing the physical linkages between observed cloud and precipitation profiles to the major processes of phase change of atmospheric water. Specifically, rain is segregated into three rain types: warm, convective, and stratiform rain, based on their dynamical and thermodynamical characteristics. As the second of series, both convective and stratiform rain LH algorithms are presented and evaluated here. For convective and stratiform rain, the major LH-related microphysical processes including condensation, deposition, evaporation, sublimation, and freezing–melting are parameterized with the aid of Cloud Resolving Model (CRM) simulations. The condensation and deposition processes are parameterized in terms of rain formation processes through the precipitation formation theory. LH associated with the freezing–melting process is relatively small and is assumed to be a fraction of total condensation and deposition LH. The evaporation and sublimation processes are parameterized for three unsaturated scenarios: rain out of the cloud body, clouds at cloud boundary and clouds and rain in downdraft region. The evaluation or self-consistency test indicates the retrievals capture the major features of LH profiles and reproduce the double peaks at right altitudes. The LH products are applicable at various stages of cloud system life cycle for high-resolution models, as well as for large-scale climate models. -- Highlights: ► An exploratory study on physics-based cold rain latent heat retrieval algorithm. ► Utilize the full information of the vertical structures of cloud and rainfall. ► Include all major LH-related microphysical processes (in ice and liquid phase). ► Directly link water mass measurements to latent heat at instantaneous pixel level. ► Applicable at various stages of cloud system life cycle

  16. A cloud chemistry module for the 3-D cloud-resolving mesoscale model Meso-NH with application to idealized cases

    Directory of Open Access Journals (Sweden)

    M. Leriche

    2013-08-01

    Full Text Available A complete chemical module has been developed for use in the Meso-NH three-dimensional cloud resolving mesoscale model. This module includes gaseous- and aqueous-phase chemical reactions that are analysed by a pre-processor generating the Fortran90 code automatically. The kinetic solver is based on a Rosenbrock algorithm, which is robust and accurate for integrating stiff systems and especially multiphase chemistry. The exchange of chemical species between the gas phase and cloud droplets and raindrops is computed kinetically by mass transfers considering non-equilibrium between the gas- and the condensed phases. Microphysical transfers of chemical species are considered for the various cloud microphysics schemes available, which are based on one-moment or two-moment schemes. The pH of the droplets and of the raindrops is diagnosed separately as the root of a high order polynomial equation. The chemical concentrations in the ice phase are modelled in a single phase encompassing the two categories of precipitating ice particles (snow and graupel of the microphysical scheme. The only process transferring chemical species in ice is retention during freezing or riming of liquid hydrometeors. Three idealized simulations are reported, which highlight the sensitivity of scavenging efficiency to the choice of the microphysical scheme and the retention coefficient in the ice phase. A two-dimensional warm, shallow convection case is used to compare the impact of the microphysical schemes on the temporal evolution and rates of acid precipitation. Acid wet deposition rates are shown to be overestimated when a one-moment microphysics scheme is used compared to a two-moment scheme. The difference is induced by a better prediction of raindrop radius and raindrop number concentration in the latter scheme. A two-dimensional mixed-phase squall line and a three-dimensional mixed-phase supercell were simulated to test the sensitivity of cloud vertical transport to

  17. Engineering analysis of the two-stage trifluoride precipitation process

    International Nuclear Information System (INIS)

    Luerkens, D.w.W.

    1984-06-01

    An engineering analysis of two-stage trifluoride precipitation processes is developed. Precipitation kinetics are modeled using consecutive reactions to represent fluoride complexation. Material balances across the precipitators are used to model the time dependent concentration profiles of the main chemical species. The results of the engineering analysis are correlated with previous experimental work on plutonium trifluoride and cerium trifluoride

  18. Radioactive demonstration of the ''late wash'' Precipitate Hydrolysis Process

    International Nuclear Information System (INIS)

    Bibler, N.E.; Ferrara, D.M.; Ha, B.C.

    1992-01-01

    This report presents results of the radioactive demonstration of the DWPF Precipitate Hydrolysis Process as it would occur in the ''late wash'' flowsheet in the absence of hydroxylamine nitrate. Radioactive precipitate containing Cs-137 from the April, 1983, in-tank precipitation demonstration in Tank 48 was used for these tests

  19. A Madden-Julian oscillation event realistically simulated by a global cloud-resolving model.

    Science.gov (United States)

    Miura, Hiroaki; Satoh, Masaki; Nasuno, Tomoe; Noda, Akira T; Oouchi, Kazuyoshi

    2007-12-14

    A Madden-Julian Oscillation (MJO) is a massive weather event consisting of deep convection coupled with atmospheric circulation, moving slowly eastward over the Indian and Pacific Oceans. Despite its enormous influence on many weather and climate systems worldwide, it has proven very difficult to simulate an MJO because of assumptions about cumulus clouds in global meteorological models. Using a model that allows direct coupling of the atmospheric circulation and clouds, we successfully simulated the slow eastward migration of an MJO event. Topography, the zonal sea surface temperature gradient, and interplay between eastward- and westward-propagating signals controlled the timing of the eastward transition of the convective center. Our results demonstrate the potential making of month-long MJO predictions when global cloud-resolving models with realistic initial conditions are used.

  20. A Robust Multi-Scale Modeling System for the Study of Cloud and Precipitation Processes

    Science.gov (United States)

    Tao, Wei-Kuo

    2012-01-01

    During the past decade, numerical weather and global non-hydrostatic models have started using more complex microphysical schemes originally developed for high resolution cloud resolving models (CRMs) with 1-2 km or less horizontal resolutions. These microphysical schemes affect the dynamic through the release of latent heat (buoyancy loading and pressure gradient) the radiation through the cloud coverage (vertical distribution of cloud species), and surface processes through rainfall (both amount and intensity). Recently, several major improvements of ice microphysical processes (or schemes) have been developed for cloud-resolving model (Goddard Cumulus Ensemble, GCE, model) and regional scale (Weather Research and Forecast, WRF) model. These improvements include an improved 3-ICE (cloud ice, snow and graupel) scheme (Lang et al. 2010); a 4-ICE (cloud ice, snow, graupel and hail) scheme and a spectral bin microphysics scheme and two different two-moment microphysics schemes. The performance of these schemes has been evaluated by using observational data from TRMM and other major field campaigns. In this talk, we will present the high-resolution (1 km) GeE and WRF model simulations and compared the simulated model results with observation from recent field campaigns [i.e., midlatitude continental spring season (MC3E; 2010), high latitude cold-season (C3VP, 2007; GCPEx, 2012), and tropical oceanic (TWP-ICE, 2006)].

  1. Microphysical variability of vigorous Amazonian deep convection observed by CloudSat, and relevance for cloud-resolving model

    Science.gov (United States)

    Dodson, J. B.; Taylor, P. C.

    2017-12-01

    The number and varieties of both satellite cloud observations and cloud simulations are increasing rapidly. This create a challenge in identifying the best methods for quantifying the physical processes associated with deep convection, and then comparing convective observations with simulations. The use of satellite simulators in conjunction with model output is an increasingly popular method of comparison studies. However, the complexity of deep convective systems renders simplistic comparison metrics hazardous, possibly resulting is misleading or even contradicting conclusions. To investigate this, CloudSat observations of Amazonian deep convective cores (DCCs) and associated anvils are compared and contrasted with output from cloud resolving models in a manner that both highlights microphysical proprties of observed convection, and displays the effects of microphysical parameterizations on allowing robust comparisons. First, contoured frequency by altitude diagrams (CFAD) are calculated from the reflectivity fields of DCCs observed by CloudSat. This reveals two distinct modes of hydrometeor variability in the high level cloud region, with one dominated by snow and aggregates, and the other by large graupel and hail. Second, output from the superparameterized Community Atmospheric Model (SP-CAM) data are processed with the Quickbeam radar simulator to produce CFADs which can be compared with the observed CFADs. Two versions of SP-CAM are used, with one (version 4) having single-moment microphysics which excludes graupel/hail, and the other (version 5) a double-moment scheme with graupel. The change from version 4 to 5 improves the reflectivity CFAD, even without corresponding changes to non-hydrometeor fields such as vertical velocity. However, it does not produce a realistic double hydrometeor mode. Finally, the influences of microphysics are further tested in the System for Atmospheric Modeling (SAM), which allows for higher control over model parameters than

  2. Continuous precipitation of uranium peroxide in process pilot plant

    International Nuclear Information System (INIS)

    Quinelato, A.L.

    1990-01-01

    An experimental study on uranium peroxide precipitation has been carried out with the objective to evaluate the influence of the main process parameters with a technological approach. The uraniferous solution used was obtained from the hydrometallurgical processing of an ore from Itataia - CE. Studies were developed in two distinct experimental stages. In the first stage, the precipitation was investigated by means of laboratory batch tests and, in the second stage, by means of continuous operation in a process pilot plant. (author)

  3. Continuous precipitation process of plutonium salts; Procede continu de precipitation des sels de plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Richard, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-03-01

    This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [French] Cette etude porte sur la precipitation continue de l'oxalate de plutonium. L'etude de la solubilite des differentes valences du plutonium dans des milieux acides nitrique-oxalique, puis nitrique-sulfurique-oxalique conduit a choisir la precipitation de l'oxalate de plutonium tetravalent. L'etude porte ensuite sur la sedimentation et la granulometrie de l'oxalate de Pu{sup 4+} obtenue en faisant varier differents parametres de la precipitation : la temperature, l'acidite, l'exces oxalique et le temps de murissement. La derniere partie traite des resultats obtenus avec plusieurs types d'appareils continus essayes au laboratoire. En conclusion sont donnees les conditions de marche de l'appareil tubulaire adopte, ainsi qu'une extrapolation a l'echelle industrielle sous forme d'un flow-sheet. (auteur)

  4. Clausius-Clapeyron Scaling of Convective Available Potential Energy (CAPE) in Cloud-Resolving Simulations

    Science.gov (United States)

    Seeley, J.; Romps, D. M.

    2015-12-01

    Recent work by Singh and O'Gorman has produced a theory for convective available potential energy (CAPE) in radiative-convective equilibrium. In this model, the atmosphere deviates from a moist adiabat—and, therefore, has positive CAPE—because entrainment causes evaporative cooling in cloud updrafts, thereby steepening their lapse rate. This has led to the proposal that CAPE increases with global warming because the strength of evaporative cooling scales according to the Clausius-Clapeyron (CC) relation. However, CAPE could also change due to changes in cloud buoyancy and changes in the entrainment rate, both of which could vary with global warming. To test the relative importance of changes in CAPE due to CC scaling of evaporative cooling, changes in cloud buoyancy, and changes in the entrainment rate, we subject a cloud-resolving model to a suite of natural (and unnatural) forcings. We find that CAPE changes are primarily driven by changes in the strength of evaporative cooling; the effect of changes in the entrainment rate and cloud buoyancy are comparatively small. This builds support for CC scaling of CAPE.

  5. Global Precipitation Measurement (GPM) Mission: Precipitation Processing System (PPS) GPM Mission Gridded Text Products Provide Surface Precipitation Retrievals

    Science.gov (United States)

    Stocker, Erich Franz; Kelley, O.; Kummerow, C.; Huffman, G.; Olson, W.; Kwiatkowski, J.

    2015-01-01

    In February 2015, the Global Precipitation Measurement (GPM) mission core satellite will complete its first year in space. The core satellite carries a conically scanning microwave imager called the GPM Microwave Imager (GMI), which also has 166 GHz and 183 GHz frequency channels. The GPM core satellite also carries a dual frequency radar (DPR) which operates at Ku frequency, similar to the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar, and a new Ka frequency. The precipitation processing system (PPS) is producing swath-based instantaneous precipitation retrievals from GMI, both radars including a dual-frequency product, and a combined GMIDPR precipitation retrieval. These level 2 products are written in the HDF5 format and have many additional parameters beyond surface precipitation that are organized into appropriate groups. While these retrieval algorithms were developed prior to launch and are not optimal, these algorithms are producing very creditable retrievals. It is appropriate for a wide group of users to have access to the GPM retrievals. However, for researchers requiring only surface precipitation, these L2 swath products can appear to be very intimidating and they certainly do contain many more variables than the average researcher needs. Some researchers desire only surface retrievals stored in a simple easily accessible format. In response, PPS has begun to produce gridded text based products that contain just the most widely used variables for each instrument (surface rainfall rate, fraction liquid, fraction convective) in a single line for each grid box that contains one or more observations.This paper will describe the gridded data products that are being produced and provide an overview of their content. Currently two types of gridded products are being produced: (1) surface precipitation retrievals from the core satellite instruments GMI, DPR, and combined GMIDPR (2) surface precipitation retrievals for the partner constellation

  6. Estimation of convective entrainment properties from a cloud-resolving model simulation during TWP-ICE

    Science.gov (United States)

    Zhang, Guang J.; Wu, Xiaoqing; Zeng, Xiping; Mitovski, Toni

    2016-10-01

    The fractional entrainment rate in convective clouds is an important parameter in current convective parameterization schemes of climate models. In this paper, it is estimated using a 1-km-resolution cloud-resolving model (CRM) simulation of convective clouds from TWP-ICE (the Tropical Warm Pool-International Cloud Experiment). The clouds are divided into different types, characterized by cloud-top heights. The entrainment rates and moist static energy that is entrained or detrained are determined by analyzing the budget of moist static energy for each cloud type. Results show that the entrained air is a mixture of approximately equal amount of cloud air and environmental air, and the detrained air is a mixture of ~80 % of cloud air and 20 % of the air with saturation moist static energy at the environmental temperature. After taking into account the difference in moist static energy between the entrained air and the mean environment, the estimated fractional entrainment rate is much larger than those used in current convective parameterization schemes. High-resolution (100 m) large-eddy simulation of TWP-ICE convection was also analyzed to support the CRM results. It is shown that the characteristics of entrainment rates estimated using both the high-resolution data and CRM-resolution coarse-grained data are similar. For each cloud category, the entrainment rate is high near cloud base and top, but low in the middle of clouds. The entrainment rates are best fitted to the inverse of in-cloud vertical velocity by a second order polynomial.

  7. Evaluation of cloud resolving model simulations of midlatitude cirrus with ARM and A-Train observations

    Science.gov (United States)

    Muehlbauer, A. D.; Ackerman, T. P.; Lawson, P.; Xie, S.; Zhang, Y.

    2015-12-01

    This paper evaluates cloud resolving model (CRM) and cloud system-resolving model (CSRM) simulations of a midlatitude cirrus case with comprehensive observations collected under the auspices of the Atmospheric Radiation Measurements (ARM) program and with spaceborne observations from the National Aeronautics and Space Administration (NASA) A-train satellites. Vertical profiles of temperature, relative humidity and wind speeds are reasonably well simulated by the CSRM and CRM but there are remaining biases in the temperature, wind speeds and relative humidity, which can be mitigated through nudging the model simulations toward the observed radiosonde profiles. Simulated vertical velocities are underestimated in all simulations except in the CRM simulations with grid spacings of 500m or finer, which suggests that turbulent vertical air motions in cirrus clouds need to be parameterized in GCMs and in CSRM simulations with horizontal grid spacings on the order of 1km. The simulated ice water content and ice number concentrations agree with the observations in the CSRM but are underestimated in the CRM simulations. The underestimation of ice number concentrations is consistent with the overestimation of radar reflectivity in the CRM simulations and suggests that the model produces too many large ice particles especially toward cloud base. Simulated cloud profiles are rather insensitive to perturbations in the initial conditions or the dimensionality of the model domain but the treatment of the forcing data has a considerable effect on the outcome of the model simulations. Despite considerable progress in observations and microphysical parameterizations, simulating the microphysical, macrophysical and radiative properties of cirrus remains challenging. Comparing model simulations with observations from multiple instruments and observational platforms is important for revealing model deficiencies and for providing rigorous benchmarks. However, there still is considerable

  8. Dynamic process model of a plutonium oxalate precipitator

    International Nuclear Information System (INIS)

    Borgonovi, G.M.; Hammelman, J.E.; Miller, C.L.

    1980-01-01

    A dynamic model of a plutonium oxalate precipitator is developed to provide a means of predicting plutonium inventory on a continuous basis. The model is based on state-of-the-art crystallization equations, which describe nucleation and growth phenomena. The model parameters were obtained through the use of batch experimental data. The model has been used to study the approach to steady state, to investigate the response to input transients, and to simulate the control of the precipitation process. 12 refs

  9. An Optical Lightning Simulator in an Electrified Cloud-Resolving Model to Prepare the Future Space Lightning Missions

    Science.gov (United States)

    Bovalo, Christophe; Defer, Eric; Pinty, Jean-Pierre

    2016-04-01

    The future decade will see the launch of several space missions designed to monitor the total lightning activity. Among these missions, the American (Geostationary Lightning Mapper - GLM) and European (Lightning Imager - LI) optical detectors will be onboard geostationary satellites (GOES-R and MTG, respectively). For the first time, the total lightning activity will be monitored over the full Earth disk and at a very high temporal resolution (2 and 1 ms, respectively). Missions like the French Tool for the Analysis of Radiation from lightNIng and Sprites (TARANIS) and ISS-LIS will bring complementary information in order to better understand the lightning physics and to improve the weather prediction (nowcasting and forecasting). Such missions will generate a huge volume of new and original observations for the scientific community and weather prediction centers that have to be prepared. Moreover, before the launch of these missions, fundamental questions regarding the interpretation of the optical signal property and its relation to cloud optical thickness and lightning discharge processes need to be further investigated. An innovative approach proposed here is to use the synergy existing in the French MesoNH Cloud-Resolving Model (CRM). Indeed, MesoNH is one of the only CRM able to simulate the lifecycle of electrical charges generated within clouds through non-inductive charging process (dependent of the 1-moment microphysical scheme). The lightning flash geometry is based on a fractal law while the electrical field is diagnosed thanks to the Gauss' law. The lightning optical simulator is linked to the electrical scheme as the lightning radiance at 777.4 nm is a function of the lightning current, approximated by the charges neutralized along the lightning path. Another important part is the scattering of this signal by the hydrometeors (mainly ice particles) that is taken into account. Simulations at 1-km resolution are done over the Langmuir Laboratory (New

  10. A new single-moment microphysics scheme for cloud-resolving models using observed dependence of ice concentration on temperature.

    Science.gov (United States)

    Khairoutdinov, M.

    2015-12-01

    The representation of microphysics, especially ice microphysics, remains one of the major uncertainties in cloud-resolving models (CRMs). Most of the cloud schemes use the so-called bulk microphysics approach, in which a few moments of such distributions are used as the prognostic variables. The System for Atmospheric Modeling (SAM) is the CRM that employs two such schemes. The single-moment scheme, which uses only mass for each of the water phases, and the two-moment scheme, which adds the particle concentration for each of the hydrometeor category. Of the two, the single-moment scheme is much more computationally efficient as it uses only two prognostic microphysics variables compared to ten variables used by the two-moment scheme. The efficiency comes from a rather considerable oversimplification of the microphysical processes. For instance, only a sum of the liquid and icy cloud water is predicted with the temperature used to diagnose the mixing ratios of different hydrometeors. The main motivation for using such simplified microphysics has been computational efficiency, especially in the applications of SAM as the super-parameterization in global climate models. Recently, we have extended the single-moment microphysics by adding only one additional prognostic variable, which has, nevertheless, allowed us to separate the cloud ice from liquid water. We made use of some of the recent observations of ice microphysics collected at various parts of the world to parameterize several aspects of ice microphysics that have not been explicitly represented before in our sing-moment scheme. For example, we use the observed broad dependence of ice concentration on temperature to diagnose the ice concentration in addition to prognostic mass. Also, there is no artificial separation between the pristine ice and snow, often used by bulk models. Instead we prescribed the ice size spectrum as the gamma distribution, with the distribution shape parameter controlled by the

  11. Dynamic process model of a plutonium oxalate precipitator. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Miller, C.L.; Hammelman, J.E.; Borgonovi, G.M.

    1977-11-01

    In support of LLL material safeguards program, a dynamic process model was developed which simulates the performance of a plutonium (IV) oxalate precipitator. The plutonium oxalate precipitator is a component in the plutonium oxalate process for making plutonium oxide powder from plutonium nitrate. The model is based on state-of-the-art crystallization descriptive equations, the parameters of which are quantified through the use of batch experimental data. The dynamic model predicts performance very similar to general Hanford oxalate process experience. The utilization of such a process model in an actual plant operation could promote both process control and material safeguards control by serving as a baseline predictor which could give early warning of process upsets or material diversion. The model has been incorporated into a FORTRAN computer program and is also compatible with the DYNSYS 2 computer code which is being used at LLL for process modeling efforts.

  12. Dynamic process model of a plutonium oxalate precipitator. Final report

    International Nuclear Information System (INIS)

    Miller, C.L.; Hammelman, J.E.; Borgonovi, G.M.

    1977-11-01

    In support of LLL material safeguards program, a dynamic process model was developed which simulates the performance of a plutonium (IV) oxalate precipitator. The plutonium oxalate precipitator is a component in the plutonium oxalate process for making plutonium oxide powder from plutonium nitrate. The model is based on state-of-the-art crystallization descriptive equations, the parameters of which are quantified through the use of batch experimental data. The dynamic model predicts performance very similar to general Hanford oxalate process experience. The utilization of such a process model in an actual plant operation could promote both process control and material safeguards control by serving as a baseline predictor which could give early warning of process upsets or material diversion. The model has been incorporated into a FORTRAN computer program and is also compatible with the DYNSYS 2 computer code which is being used at LLL for process modeling efforts

  13. Dynamic simulation of the in-tank precipitation process

    International Nuclear Information System (INIS)

    Hang, T.; Shanahan, K.L.; Gregory, M.V.; Walker, D.D.

    1993-01-01

    As part of the High-Level Waste Tank Farm at the Savannah River Site (SRS), the In-Tank Precipitation (ITP) facility was designed to decontaminate the radioactive waste supernate by removing cesium as precipitated cesium tetraphenylborate. A dynamic computer model of the ITP process was developed using SPEEDUP TM software to provide guidance in the areas of operation and production forecast, production scheduling, safety, air emission, and process improvements. The model performs material balance calculations in all phase (solid, liquid, and gas) for 50 key chemical constituents to account for inventory accumulation, depletion, and dilution. Calculations include precipitation, benzene radiolytic reactions, evaporation, dissolution, adsorption, filtration, and stripping. To control the ITP batch operation a customized FORTRAN program was generated and linked to SPEEDUP TM simulation This paper summarizes the model development and initial results of the simulation study

  14. Stoichiometric hydroxyapatite obtained by precipitation and sol gel processes

    Energy Technology Data Exchange (ETDEWEB)

    Guzman V, C.; Pina B, C.; Munguia, N. [IIM-UNAM, A.P. 70-360, 04510 Mexico D.F. (Mexico)]. e-mail: caroguz@servidor.unam.mx

    2005-07-01

    Three methods for obtaining hydroxyapatite (HA) are described. HA is a very interesting ceramic because of its many medical applications. The first two precipitation methods start from calcium and phosphorous compounds, whereas the third method is a sol-gel process that uses alkoxides. The products were characterized and compared. The observed differences are important for practical applications. (Author)

  15. Ensemble cloud-resolving modelling of a historic back-building mesoscale convective system over Liguria: the San Fruttuoso case of 1915

    Science.gov (United States)

    Parodi, Antonio; Ferraris, Luca; Gallus, William; Maugeri, Maurizio; Molini, Luca; Siccardi, Franco; Boni, Giorgio

    2017-05-01

    Highly localized and persistent back-building mesoscale convective systems represent one of the most dangerous flash-flood-producing storms in the north-western Mediterranean area. Substantial warming of the Mediterranean Sea in recent decades raises concerns over possible increases in frequency or intensity of these types of events as increased atmospheric temperatures generally support increases in water vapour content. However, analyses of the historical record do not provide a univocal answer, but these are likely affected by a lack of detailed observations for older events. In the present study, 20th Century Reanalysis Project initial and boundary condition data in ensemble mode are used to address the feasibility of performing cloud-resolving simulations with 1 km horizontal grid spacing of a historic extreme event that occurred over Liguria: the San Fruttuoso case of 1915. The proposed approach focuses on the ensemble Weather Research and Forecasting (WRF) model runs that show strong convergence over the Ligurian Sea (17 out of 56 members) as these runs are the ones most likely to best simulate the event. It is found that these WRF runs generally do show wind and precipitation fields that are consistent with the occurrence of highly localized and persistent back-building mesoscale convective systems, although precipitation peak amounts are underestimated. Systematic small north-westward position errors with regard to the heaviest rain and strongest convergence areas imply that the reanalysis members may not be adequately representing the amount of cool air over the Po Plain outflowing into the Ligurian Sea through the Apennines gap. Regarding the role of historical data sources, this study shows that in addition to reanalysis products, unconventional data, such as historical meteorological bulletins, newspapers, and even photographs, can be very valuable sources of knowledge in the reconstruction of past extreme events.

  16. Feasibility of performing high resolution cloud-resolving simulations of historic extreme events: The San Fruttuoso (Liguria, italy) case of 1915.

    Science.gov (United States)

    Parodi, Antonio; Boni, Giorgio; Ferraris, Luca; Gallus, William; Maugeri, Maurizio; Molini, Luca; Siccardi, Franco

    2017-04-01

    Recent studies show that highly localized and persistent back-building mesoscale convective systems represent one of the most dangerous flash-flood producing storms in the north-western Mediterranean area. Substantial warming of the Mediterranean Sea in recent decades raises concerns over possible increases in frequency or intensity of these types of events as increased atmospheric temperatures generally support increases in water vapor content. Analyses of available historical records do not provide a univocal answer, since these may be likely affected by a lack of detailed observations for older events. In the present study, 20th Century Reanalysis Project initial and boundary condition data in ensemble mode are used to address the feasibility of performing cloud-resolving simulations with 1 km horizontal grid spacing of a historic extreme event that occurred over Liguria (Italy): The San Fruttuoso case of 1915. The proposed approach focuses on the ensemble Weather Research and Forecasting (WRF) model runs, as they are the ones most likely to best simulate the event. It is found that these WRF runs generally do show wind and precipitation fields that are consistent with the occurrence of highly localized and persistent back-building mesoscale convective systems, although precipitation peak amounts are underestimated. Systematic small north-westward position errors with regard to the heaviest rain and strongest convergence areas imply that the Reanalysis members may not be adequately representing the amount of cool air over the Po Plain outflowing into the Liguria Sea through the Apennines gap. Regarding the role of historical data sources, this study shows that in addition to Reanalysis products, unconventional data, such as historical meteorological bulletins, newspapers and even photographs can be very valuable sources of knowledge in the reconstruction of past extreme events.

  17. Chemical precipitation processes for the treatment of aqueous radioactive waste

    International Nuclear Information System (INIS)

    1992-01-01

    Chemical precipitation by coagulation-flocculation and sedimentation has been commonly used for many years to treat liquid (aqueous) radioactive waste. This method allows the volume of waste to be substantially reduced for further treatment or conditioning and the bulk of the waste to de discharged. Chemical precipitation is usually applied in combination with other methods as part of a comprehensive waste management scheme. As with any other technology, chemical precipitation is constantly being improved to reduce cost to increase the effectiveness and safety on the entire waste management system. The purpose of this report is to review and update the information provided in Technical Reports Series No. 89, Chemical Treatment of Radioactive Wastes, published in 1968. In this report the chemical methods currently in use for the treatment of low and intermediate level aqueous radioactive wastes are described and illustrated. Comparisons are given of the advantages and limitations of the processes, and it is noted that good decontamination and volume reduction are not the only criteria according to which a particular process should be selected. Emphasis has been placed on the need to carefully characterize each waste stream, to examine fully the effect of segregation and the importance of looking at the entire operation and not just the treatment process when planning a liquid waste treatment facility. This general approach includes local requirements and possibilities, discharge authorization, management of the concentrates, ICRP recommendations and economics. It appears that chemical precipitation process and solid-liquid separation techniques will continue to be widely used in liquid radioactive waste treatment. Current research and development is showing that combining different processes in one treatment plant can provide higher decontamination factors and smaller secondary waste arisings. Some of these processes are already being incorporated into new and

  18. Process Control for Precipitation Prevention in Space Water Recovery Systems

    Science.gov (United States)

    Sargusingh, Miriam; Callahan, Michael R.; Muirhead, Dean

    2015-01-01

    The ability to recover and purify water through physiochemical processes is crucial for realizing long-term human space missions, including both planetary habitation and space travel. Because of their robust nature, rotary distillation systems have been actively pursued by NASA as one of the technologies for water recovery from wastewater primarily comprised of human urine. A specific area of interest is the prevention of the formation of solids that could clog fluid lines and damage rotating equipment. To mitigate the formation of solids, operational constraints are in place that limits such that the concentration of key precipitating ions in the wastewater brine are below the theoretical threshold. This control in effected by limiting the amount of water recovered such that the risk of reaching the precipitation threshold is within acceptable limits. The water recovery limit is based on an empirically derived worst case wastewater composition. During the batch process, water recovery is estimated by monitoring the throughput of the system. NASA Johnson Space Center is working on means of enhancing the process controls to increase water recovery. Options include more precise prediction of the precipitation threshold. To this end, JSC is developing a means of more accurately measuring the constituent of the brine and/or wastewater. Another means would be to more accurately monitor the throughput of the system. In spring of 2015, testing will be performed to test strategies for optimizing water recovery without increasing the risk of solids formation in the brine.

  19. Comparison of convective clouds observed by spaceborne W-band radar and simulated by cloud-resolving atmospheric models

    Science.gov (United States)

    Dodson, Jason B.

    Deep convective clouds (DCCs) play an important role in regulating global climate through vertical mass flux, vertical water transport, and radiation. For general circulation models (GCMs) to simulate the global climate realistically, they must simulate DCCs realistically. GCMs have traditionally used cumulus parameterizations (CPs). Much recent research has shown that multiple persistent unrealistic behaviors in GCMs are related to limitations of CPs. Two alternatives to CPs exist: the global cloud-resolving model (GCRM), and the multiscale modeling framework (MMF). Both can directly simulate the coarser features of DCCs because of their multi-kilometer horizontal resolutions, and can simulate large-scale meteorological processes more realistically than GCMs. However, the question of realistic behavior of simulated DCCs remains. How closely do simulated DCCs resemble observed DCCs? In this study I examine the behavior of DCCs in the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) and Superparameterized Community Atmospheric Model (SP-CAM), the latter with both single-moment and double-moment microphysics. I place particular emphasis on the relationship between cloud vertical structure and convective environment. I also emphasize the transition between shallow clouds and mature DCCs. The spatial domains used are the tropical oceans and the contiguous United States (CONUS), the latter of which produces frequent vigorous convection during the summer. CloudSat is used to observe DCCs, and A-Train and reanalysis data are used to represent the large-scale environment in which the clouds form. The CloudSat cloud mask and radar reflectivity profiles for CONUS cumuliform clouds (defined as clouds with a base within the planetary boundary layer) during boreal summer are first averaged and compared. Both NICAM and SP-CAM greatly underestimate the vertical growth of cumuliform clouds. Then they are sorted by three large-scale environmental variables: total preciptable

  20. Concentration of light rare earths process by amoniacal precipitation

    International Nuclear Information System (INIS)

    Aguilera, Y.; Rapado, M.; Consuegra, R.

    1996-01-01

    A procedure for the separation and concentration of light rare earths using a mixture of ammonia and water was developed. As a result technical concentrates of rare earths were obtained and the physical separation in the filtration step was improved. The filtration parameters (cake resistance r 0 and filtration web resistance R) were obtained for this process being they 5,5.10 11 cm/g and 3,4.10 13 cm -1 respectively. The proposed technology concentrates (Ce, La and Nd) with purities ranging from: 85-90 %, 85-87 % and 42-65 % respectively in only one precipitation step

  1. Stochastic investigation of precipitation process for climatic variability identification

    Science.gov (United States)

    Sotiriadou, Alexia; Petsiou, Amalia; Feloni, Elisavet; Kastis, Paris; Iliopoulou, Theano; Markonis, Yannis; Tyralis, Hristos; Dimitriadis, Panayiotis; Koutsoyiannis, Demetris

    2016-04-01

    The precipitation process is important not only to hydrometeorology but also to renewable energy resources management. We use a dataset consisting of daily and hourly records around the globe to identify statistical variability with emphasis on the last period. Specifically, we investigate the occurrence of mean, maximum and minimum values and we estimate statistical properties such as marginal probability distribution function and the type of decay of the climacogram (i.e., mean process variance vs. scale). Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  2. Processing of tetraphenylborate precipitates in the Savannah River Site Defense Waste Processing Facility

    International Nuclear Information System (INIS)

    Eibling, R.E.

    1990-01-01

    The Savannah River Site has generated 77 million gallons of high level radioactive waste since the early 1950's. By 1987, evaporation had reduced the concentration of the waste inventory to 35 million gallons. Currently, the wastes reside in large underground tanks as a soluble fraction stored, crystallized salts, and an insoluble fraction, sludge, which consists of hydrated transition metal oxides. The bulk of the radionuclides, 67 percent, are in the sludge while the crystallized salts and supernate are composed of the nitrates, nitrites, sulfates and hydroxides of sodium, potassium, and cesium. The principal radionuclide in the soluble waste is 137 Cs with traces of 90 Sr. The transformation of the high level wastes into a borosilicate glass suitable for permanent disposal is the goal of the Defense Waste Processing Facility (DWPF). To minimize the volume of glass produced, the soluble fraction of the waste is treated with sodium tetraphenylborate and sodium titanate in the waste tanks to precipitate the radioactive cesium ion and absorb the radioactive strontium ion. The precipitate is washed in the waste tanks and is then pumped to the DWPF. The precipitate, as received, is incompatible with the vitrification process because of the high aromatic carbon content and requires further chemical treatment. Within the DWPF, the precipitate is processed in the Salt Processing Cell to remove the aromatic carbon as benzene. The precipitate hydrolysis process hydrolyzes the tetraphenylborate anion to produce borate anion and benzene. The benzene is removed by distillation, decontaminated and transferred out of the DWPF for disposal

  3. Liquid waste processing from plutonium (III) oxalate precipitation

    International Nuclear Information System (INIS)

    Esteban, A.; Cassaniti, P.; Orosco, E.H.

    1990-01-01

    Plutonium (III) oxalate filtrates contain about 0.2M oxalic acid, 0.09M ascorbic acid, 0.05M hydrazine, 1M nitric acid and 20-100 mg/l of plutonium. The developed treatment of liquid wastes consist in two main steps: a) Distillation to reduce up to 10% of the initial volume and refluxing to destroy organic material. Then, the treated solution is suitable to adjust the plutonium at the tetravalent state by addition of hydrogen peroxide and the nitric molarity up to 8.6M. b) Recovery and purification of plutonium by anion exchange using two columns in series containing Dowex 1-X4 resin. With the proposed process, it is possible to transform 38 litres of filtrates with 40mg/l of Pu into 0.1 l of purified solution with 15-20g/l of Pu. This solution is suitable to be recycled in the Pu (III) oxalate precipitation process. This process has several potential advantages over similar liquid waste treatments. These include: 1) It does not increase the liquid volume. 2) It consumes only few reagents. 3) The operations involved are simple, requiring limited handling and they are feasible to automatization. 4) The Pu recovery factor is about 99%. (Author) [es

  4. Analysis of the environments of seven Mediterranean tropical-like storms using an axisymmetric, nonhydrostatic, cloud resolving model

    Directory of Open Access Journals (Sweden)

    L. Fita

    2007-01-01

    Full Text Available Tropical-like storms on the Mediterranean Sea are occasionally observed on satellite images, often with a clear eye surrounded by an axysimmetric cloud structure. These storms sometimes attain hurricane intensity and can severely affect coastal lands. A deep, cut-off, cold-core low is usually observed at mid-upper tropospheric levels in association with the development of these tropical-like systems. In this study we attempt to apply some tools previously used in studies of tropical hurricanes to characterise the environments in which seven known Mediterranean events developed. In particular, an axisymmetric, nonhydrostatic, cloud resolving model is applied to simulate the tropical-like storm genesis and evolution. Results are compared to surface observations when landfall occurred and with satellite microwave derived wind speed measurements over the sea. Finally, sensitivities of the numerical simulations to different factors (e.g. sea surface temperature, vertical humidity profile and size of the initial precursor of the storm are examined.

  5. Improving representation of convective transport for scale-aware parameterization: 2. Analysis of cloud-resolving model simulations

    Science.gov (United States)

    Liu, Yi-Chin; Fan, Jiwen; Zhang, Guang J.; Xu, Kuan-Man; Ghan, Steven J.

    2015-04-01

    Following Part I, in which 3-D cloud-resolving model (CRM) simulations of a squall line and mesoscale convective complex in the midlatitude continental and the tropical regions are conducted and evaluated, we examine the scale dependence of eddy transport of water vapor, evaluate different eddy transport formulations, and improve the representation of convective transport across all scales by proposing a new formulation that more accurately represents the CRM-calculated eddy flux. CRM results show that there are strong grid-spacing dependencies of updraft and downdraft fractions regardless of altitudes, cloud life stage, and geographical location. As for the eddy transport of water vapor, updraft eddy flux is a major contributor to total eddy flux in the lower and middle troposphere. However, downdraft eddy transport can be as large as updraft eddy transport in the lower atmosphere especially at the mature stage of midlatitude continental convection. We show that the single-updraft approach significantly underestimates updraft eddy transport of water vapor because it fails to account for the large internal variability of updrafts, while a single downdraft represents the downdraft eddy transport of water vapor well. We find that using as few as three updrafts can account for the internal variability of updrafts well. Based on the evaluation with the CRM simulated data, we recommend a simplified eddy transport formulation that considers three updrafts and one downdraft. Such formulation is similar to the conventional one but much more accurately represents CRM-simulated eddy flux across all grid scales.

  6. The Neighboring Column Approximation (NCA) – A fast approach for the calculation of 3D thermal heating rates in cloud resolving models

    International Nuclear Information System (INIS)

    Klinger, Carolin; Mayer, Bernhard

    2016-01-01

    Due to computational costs, radiation is usually neglected or solved in plane parallel 1D approximation in today's numerical weather forecast and cloud resolving models. We present a fast and accurate method to calculate 3D heating and cooling rates in the thermal spectral range that can be used in cloud resolving models. The parameterization considers net fluxes across horizontal box boundaries in addition to the top and bottom boundaries. Since the largest heating and cooling rates occur inside the cloud, close to the cloud edge, the method needs in first approximation only the information if a grid box is at the edge of a cloud or not. Therefore, in order to calculate the heating or cooling rates of a specific grid box, only the directly neighboring columns are used. Our so-called Neighboring Column Approximation (NCA) is an analytical consideration of cloud side effects which can be considered a convolution of a 1D radiative transfer result with a kernel or radius of 1 grid-box (5 pt stencil) and which does usually not break the parallelization of a cloud resolving model. The NCA can be easily applied to any cloud resolving model that includes a 1D radiation scheme. Due to the neglect of horizontal transport of radiation further away than one model column, the NCA works best for model resolutions of about 100 m or lager. In this paper we describe the method and show a set of applications of LES cloud field snap shots. Correction terms, gains and restrictions of the NCA are described. Comprehensive comparisons to the 3D Monte Carlo Model MYSTIC and a 1D solution are shown. In realistic cloud fields, the full 3D simulation with MYSTIC shows cooling rates up to −150 K/d (100 m resolution) while the 1D solution shows maximum coolings of only −100 K/d. The NCA is capable of reproducing the larger 3D cooling rates. The spatial distribution of the heating and cooling is improved considerably. Computational costs are only a factor of 1.5–2 higher compared to a 1D

  7. Cloud-Resolving Modeling Intercomparison Study of a Squall Line Case from MC3E - Properties of Convective Core

    Science.gov (United States)

    Fan, J.; Han, B.; Varble, A.; Morrison, H.; North, K.; Kollias, P.; Chen, B.; Dong, X.; Giangrande, S. E.; Khain, A.; Lin, Y.; Mansell, E.; Milbrandt, J.; Stenz, R.; Thompson, G.; Wang, Y.

    2016-12-01

    The large spread in CRM model simulations of deep convection and aerosol effects on deep convective clouds (DCCs) makes it difficult to (1) further our understanding of deep convection and (2) define "benchmarks" and then limit their use in parameterization developments. A constrained model intercomparsion study on a mid-latitude mesoscale squall line is performed using the Weather Research & Forecasting (WRF) model at 1-km horizontal grid spacing with eight cloud microphysics schemes to understand specific processes that lead to the large spreads of simulated convection and precipitation. Various observational data are employed to evaluate the baseline simulations. All simulations tend to produce a wider convective area but a much narrower stratiform area. The magnitudes of virtual potential temperature drop, pressure rise, and wind speed peak associated with the passage of the gust front are significantly smaller compared with the observations, suggesting simulated cool pools are weaker. Simulations generally overestimate the vertical velocity and radar reflectivity in convective cores compared with the retrievals. The modeled updraft velocity and precipitation have a significant spread across eight schemes. The spread of updraft velocity is the combination of both low-level pressure perturbation gradient (PPG) and buoyancy. Both PPG and thermal buoyancy are small for simulations of weak convection but both are large for those of strong convection. Ice-related parameterizations contribute majorly to the spread of updraft velocity, while they are not the reason for the large spread of precipitation. The understandings gained in this study can help to focus future observations and parameterization development.

  8. Improvements on heap leaching process for a refractory uranium ore and yellow cake precipitation process

    International Nuclear Information System (INIS)

    Feng Jianke

    2013-01-01

    Some problems such as formed harden matrix, ore heap compaction, poor permeability, and agglomeration of absorption resin occur during extracting uranium from a refractory uranium ore by heap leaching process. After some measures were taken, i.e. spraying a new ore heap by low concentration acid, two or more ore heaps in series leaching, turning ores in ore heap, the permeability was improved, acid consumption was reduced. Through precipitate circulation and aging, the yellow cake slurry in amorphous or microlite form was transformed to crystal precipitate, thus uranium content in yellow cake was improved, and water content in yellow cake was lowered with good economic benefits. (author)

  9. Evaluation of cloud-resolving model simulations of midlatitude cirrus with ARM and A-train observations

    Science.gov (United States)

    Muhlbauer, A.; Ackerman, T. P.; Lawson, R. P.; Xie, S.; Zhang, Y.

    2015-07-01

    Cirrus clouds are ubiquitous in the upper troposphere and still constitute one of the largest uncertainties in climate predictions. This paper evaluates cloud-resolving model (CRM) and cloud system-resolving model (CSRM) simulations of a midlatitude cirrus case with comprehensive observations collected under the auspices of the Atmospheric Radiation Measurements (ARM) program and with spaceborne observations from the National Aeronautics and Space Administration A-train satellites. The CRM simulations are driven with periodic boundary conditions and ARM forcing data, whereas the CSRM simulations are driven by the ERA-Interim product. Vertical profiles of temperature, relative humidity, and wind speeds are reasonably well simulated by the CSRM and CRM, but there are remaining biases in the temperature, wind speeds, and relative humidity, which can be mitigated through nudging the model simulations toward the observed radiosonde profiles. Simulated vertical velocities are underestimated in all simulations except in the CRM simulations with grid spacings of 500 m or finer, which suggests that turbulent vertical air motions in cirrus clouds need to be parameterized in general circulation models and in CSRM simulations with horizontal grid spacings on the order of 1 km. The simulated ice water content and ice number concentrations agree with the observations in the CSRM but are underestimated in the CRM simulations. The underestimation of ice number concentrations is consistent with the overestimation of radar reflectivity in the CRM simulations and suggests that the model produces too many large ice particles especially toward the cloud base. Simulated cloud profiles are rather insensitive to perturbations in the initial conditions or the dimensionality of the model domain, but the treatment of the forcing data has a considerable effect on the outcome of the model simulations. Despite considerable progress in observations and microphysical parameterizations, simulating

  10. An examination of two pathways to tropical cyclogenesis occurring in idealized simulations with a cloud-resolving numerical model

    Directory of Open Access Journals (Sweden)

    M. E. Nicholls

    2013-06-01

    Full Text Available Simulations are conducted with a cloud-resolving numerical model to examine the transformation of a weak incipient mid-level cyclonic vortex into a tropical cyclone. Results demonstrate that two distinct pathways are possible and that development along a particular pathway is sensitive to model physics and initial conditions. One pathway involves a steady increase of the surface winds to tropical cyclone strength as the radius of maximum winds gradually decreases. A notable feature of this evolution is the creation of small-scale lower tropospheric cyclonic vorticity anomalies by deep convective towers and subsequent merger and convergence by the low-level secondary circulation. The second pathway also begins with a strengthening low-level circulation, but eventually a significantly stronger mid-level circulation develops. Cyclogenesis occurs subsequently when a small-scale surface concentrated vortex forms abruptly near the center of the larger-scale circulation. The small-scale vortex is warm core throughout the troposphere and results in a fall in local surface pressure of a few millibars. It usually develops rapidly, undergoing a modest growth to form a small tropical cyclone. Many of the simulated systems approach or reach tropical cyclone strength prior to development of a prominent mid-level vortex so that the subsequent formation of a strong small-scale surface concentrated vortex in these cases could be considered intensification rather than genesis. Experiments are performed to investigate the dependence on the inclusion of the ice phase, radiation, the size and strength of the incipient mid-level vortex, the amount of moisture present in the initial vortex, and the sea surface temperature. Notably, as the sea surface temperature is raised, the likelihood of development along the second pathway is increased. This appears to be related to an increased production of ice. The sensitivity of the pathway taken to model physics and initial

  11. Precipitation processes in DC-cast AlMn(Fe,Si) alloys

    International Nuclear Information System (INIS)

    Voeroes, G.; Kovacs, I.

    1990-01-01

    The precipitation processes in DC cast Al-Mn alloys were investigated by electrical resistivity measurements. It was obtained that the addition of Fe or Fe and Si influences basically the precipitation of Mn. In pure Al-Mn alloys a phase transition like behaviour was observed at about 550 degC, which can be related to the formation of two different precipitate particles below and above this temperature

  12. Dynamic modelling of processes in rivers affected by precipitation runoff

    DEFF Research Database (Denmark)

    Jacobsen, Judith L.

    1997-01-01

    In this thesis, models for the dynamics of oxygen and organic matter in receiving waters (such as rivers and creeks), which are affected by rain, are developed. A time series analysis framework is used, but presented with special emphasis on continuous time state space models. Also, the concept o....... In most models, precipitation in the form of rain have been included to study the impact from this. Finally, the future and industrial perspectives are presented, along with a list of suggestions for future research related to the subjects considered in this thesis....

  13. Nanostructure of aluminium alloy 2024: Segregation, clustering and precipitation processes

    International Nuclear Information System (INIS)

    Sha, G.; Marceau, R.K.W.; Gao, X.; Muddle, B.C.; Ringer, S.P.

    2011-01-01

    Variations in solute element distribution occurring in a commercial 2024 aluminium alloy during isothermal ageing treatments at 170 deg. C for up to 120 h have been characterized using atom probe tomography. An early (0.5 h at 170 deg. C) rapid increase in hardness was correlated with the formation of fine scale (average 24 atom) solute clusters, comprising principally Mg and Cu, but with minor concentrations of Si and Zn. There was, in addition, evidence of significant segregation of Mg, Cu and Si to at least some fraction of grain boundaries and existing matrix dislocations. At peak hardness (80 h at 170 deg. C) the microstructure comprised coarse precipitates of S phase, with a composition approaching stoichiometric Al 2 CuMg, a dense distribution of Guinier-Preston-Bagaryatsky zones elongated parallel to in a matrix of α-Al and a residual distribution of smaller equiaxed solute clusters. Both the clusters and zones contained predominantly Mg and Cu, with minor concentrations of Si and Zn. The S phase contained small but significant (0.5-1.8 at.%) concentrations of Si, which was non-uniformly distributed in elongated domains within the laths of the S phase. In overaged samples (114 h at 170 deg. C) the microstructure comprised almost exclusively coarse S phase, Al 2 Mg(Cu,Si), in assemblies suggestive of a combination of precipitate coarsening and coalescence.

  14. An Observation-based Assessment of Instrument Requirements for a Future Precipitation Process Observing System

    Science.gov (United States)

    Nelson, E.; L'Ecuyer, T. S.; Wood, N.; Smalley, M.; Kulie, M.; Hahn, W.

    2017-12-01

    Global models exhibit substantial biases in the frequency, intensity, duration, and spatial scales of precipitation systems. Much of this uncertainty stems from an inadequate representation of the processes by which water is cycled between the surface and atmosphere and, in particular, those that govern the formation and maintenance of cloud systems and their propensity to form the precipitation. Progress toward improving precipitation process models requires observing systems capable of quantifying the coupling between the ice content, vertical mass fluxes, and precipitation yield of precipitating cloud systems. Spaceborne multi-frequency, Doppler radar offers a unique opportunity to address this need but the effectiveness of such a mission is heavily dependent on its ability to actually observe the processes of interest in the widest possible range of systems. Planning for a next generation precipitation process observing system should, therefore, start with a fundamental evaluation of the trade-offs between sensitivity, resolution, sampling, cost, and the overall potential scientific yield of the mission. Here we provide an initial assessment of the scientific and economic trade-space by evaluating hypothetical spaceborne multi-frequency radars using a combination of current real-world and model-derived synthetic observations. Specifically, we alter the field of view, vertical resolution, and sensitivity of a hypothetical Ka- and W-band radar system and propagate those changes through precipitation detection and intensity retrievals. The results suggest that sampling biases introduced by reducing sensitivity disproportionately affect the light rainfall and frozen precipitation regimes that are critical for warm cloud feedbacks and ice sheet mass balance, respectively. Coarser spatial resolution observations introduce regime-dependent biases in both precipitation occurrence and intensity that depend on cloud regime, with even the sign of the bias varying within a

  15. Study of tannery wastewater treatability by precipitation process

    International Nuclear Information System (INIS)

    Abbas, N.; Deba, F.; Iqbal, K.; Shafiq, T.; Ahmed, H.S.

    2010-01-01

    A study was conducted for the removal and recovery of chromium from tannery wastewater, using NaOH, MgO, Ca(OH)/sub 2/ and Al/sub 2/(SO/sub 4/)/sub 3/.18H/sub 2/O as precipitating agents and comparing their effect on pH, total dissolved solids (TDS), total suspended solids (TSS), sludge volume and chromium removal. MgO and Ca(OH)/sub 2/ produced least amount of sludge and dewatering of sludge was also easy as compared to Al/sub 2/(SO/sub 4/)/sub 3/.18H/sub 2/O and NaOH. The chromium removal of MgO and Ca(OH)/sub 2/ was 95% and 96%, respectively. (author)

  16. Optimization of the recycling process of precipitation barren solution in a uranium mine

    International Nuclear Information System (INIS)

    Long Qing; Yu Suqin; Zhao Wucheng; Han Wei; Zhang Hui; Chen Shuangxi

    2014-01-01

    Alkaline leaching process was adopted to recover uranium from ores in a uranium mine, and high concentration uranium solution, which would be later used in precipitation, was obtained after ion-exchange and elution steps. The eluting agent consisted of NaCl and NaHCO 3 . Though precipitation barren solution contained as high as 80 g/L Na 2 CO 3 , it still can not be recycled due to presence of high Cl - concentration So, both elution and precipitation processes were optimized in order to control the Cl - concentration in the precipitation barren solution to the recyclable concentration range. Because the precipitation barren solution can be recycled by optimization, the agent consumption was lowered and the discharge of waste water was reduced. (authors)

  17. Nucleation during gibbsites precipitation with seeds from sodium aluminate solution processed under ultrasound

    Institute of Scientific and Technical Information of China (English)

    陈国辉; 陈启元; 尹周澜; 张斌

    2004-01-01

    The secondary nucleation during gibbsite precipitation with seeds from sodium aluminate solution processed by ultrasound was examined by particle size distribution(PSD) analyses. Experiments indicate that at low temperature(<65 ℃ ) and with low frequency ultrasound, the precipitation efficiency and also the secondary nucleation can be improved. Solution processed by low frequency ultrasound has more nuclei than common liquor does at low temperature. At 55 ℃, precipitation efficiency can he improved by 5.31 %, and the effect promoted by low frequency ultrasound decreases with the increase of temperature.

  18. Honeywell Modular Automation System Computer Software Documentation for the Magnesium Hydroxide Precipitation Process

    International Nuclear Information System (INIS)

    STUBBS, A.M.

    2001-01-01

    The purpose of this Computer Software Document (CSWD) is to provide configuration control of the Honeywell Modular Automation System (MAS) in use at the Plutonium Finishing Plant (PFP) for the Magnesium Hydroxide Precipitation Process in Rm 230C/234-5Z. The magnesium hydroxide process control software Rev 0 is being updated to include control programming for a second hot plate. The process control programming was performed by the system administrator. Software testing for the additional hot plate was performed per PFP Job Control Work Package 2Z-00-1703. The software testing was verified by Quality Control to comply with OSD-Z-184-00044, Magnesium Hydroxide Precipitation Process

  19. Linear Friction Welding Process Model for Carpenter Custom 465 Precipitation-Hardened Martensitic Stainless Steel

    Science.gov (United States)

    2014-04-11

    Carpenter Custom 465 precipitation-hardened martensitic stainless steel to develop a linear friction welding (LFW) process model for this material...Model for Carpenter Custom 465 Precipitation-Hardened Martensitic Stainless Steel The views, opinions and/or findings contained in this report are... Martensitic Stainless Steel Report Title An Arbitrary Lagrangian-Eulerian finite-element analysis is combined with thermo-mechanical material

  20. Innovative precipitation in emulsion process: toward a non-nuclear industrial application

    International Nuclear Information System (INIS)

    Ollivier, M.; Borda, G.; Charton, S.; Flouret, J.

    2016-01-01

    A precipitation in emulsion process has been proposed by Borda et al. in 2008 for the continuous precipitation of lanthanides or actinides as oxalate, in order to either increase the production capacity or allow the precipitation of long-life radioactive elements under optimum safety conditions. During research/development tests, a strong correlation between the emulsion's properties and those of the particles produced have been evidenced, thus enabling the size and morphology of the powder to be tuned by varying the droplets properties, the latter being controlled by the column operating conditions. This process thus appears as an attractive alternative to conventional processes for the synthesis of high-value precipitates; as it offers interesting intensification capabilities. In this context, the feasibility of the precipitation of bismuth subnitrate (BSN), for which the emulsion route for precipitation seems to be particularly attractive, has been studied. Indeed, the division of the reacting volume into droplets may allow efficient temperature regulation of the exothermic reaction. In addition, an improvement of the product appearance is expected. This first phase of the feasibility study focused on the choice of the organic phase and the sensitivity of the droplets and solid particles properties to the operating conditions. Following the encouraging results observed in stirred-tank reactor, we successfully tested the implementation in a pulsed column, at lab-scale. (authors)

  1. Innovative precipitation in emulsion process: toward a non-nuclear industrial application

    Energy Technology Data Exchange (ETDEWEB)

    Ollivier, M.; Borda, G.; Charton, S. [CEA, Centre de Marcoule, DEN,DTEC,SGCS, F-30207 Bagnols-sur-Ceze (France); Flouret, J. [OCM, ZI Quai Jean Jaures, 197 Avenue Marie Curie, 07800 La Voulte-sur-Rhone (France)

    2016-07-01

    A precipitation in emulsion process has been proposed by Borda et al. in 2008 for the continuous precipitation of lanthanides or actinides as oxalate, in order to either increase the production capacity or allow the precipitation of long-life radioactive elements under optimum safety conditions. During research/development tests, a strong correlation between the emulsion's properties and those of the particles produced have been evidenced, thus enabling the size and morphology of the powder to be tuned by varying the droplets properties, the latter being controlled by the column operating conditions. This process thus appears as an attractive alternative to conventional processes for the synthesis of high-value precipitates; as it offers interesting intensification capabilities. In this context, the feasibility of the precipitation of bismuth subnitrate (BSN), for which the emulsion route for precipitation seems to be particularly attractive, has been studied. Indeed, the division of the reacting volume into droplets may allow efficient temperature regulation of the exothermic reaction. In addition, an improvement of the product appearance is expected. This first phase of the feasibility study focused on the choice of the organic phase and the sensitivity of the droplets and solid particles properties to the operating conditions. Following the encouraging results observed in stirred-tank reactor, we successfully tested the implementation in a pulsed column, at lab-scale. (authors)

  2. From Global to Cloud Resolving Scale: Experiments with a Scale- and Aerosol-Aware Physics Package and Impact on Tracer Transport

    Science.gov (United States)

    Grell, G. A.; Freitas, S. R.; Olson, J.; Bela, M.

    2017-12-01

    We will start by providing a summary of the latest cumulus parameterization modeling efforts at NOAA's Earth System Research Laboratory (ESRL) will be presented on both regional and global scales. The physics package includes a scale-aware parameterization of subgrid cloudiness feedback to radiation (coupled PBL, microphysics, radiation, shallow and congestus type convection), the stochastic Grell-Freitas (GF) scale- and aerosol-aware convective parameterization, and an aerosol aware microphysics package. GF is based on a stochastic approach originally implemented by Grell and Devenyi (2002) and described in more detail in Grell and Freitas (2014, ACP). It was expanded to include PDF's for vertical mass flux, as well as modifications to improve the diurnal cycle. This physics package will be used on different scales, spanning global to cloud resolving, to look at the impact on scalar transport and numerical weather prediction.

  3. An Improved Process for Precipitating Cyanide Ions from the Barren Solution at Different pHs

    Science.gov (United States)

    Figueroa, Gabriela V.; Parga, José R.; Valenzuela, Jesus L.; Vázquez, Victor; Valenzuela, Alejandro; Rodriguez, Mario

    2016-02-01

    In recent decades, the use of metal sulfides instead of hydroxide precipitation in hydrometallurgical processes has gained prominence. Some arguments for its preferential use are as follows: a high degree of metal removal at relatively low pH values, the sparingly soluble nature of sulfide precipitates, favorable dewatering characteristics, and the stability of the formed metal sulfides. The Merrill-Crowe zinc-precipitation process has been applied worldwide in a large number of operations for the recovery of gold and silver from cyanide solutions. However, in some larger plants, the quality of this precious precipitate is low because copper, zinc and especially lead are precipitated along with gold and silver. This results in higher consumption of zinc dust and flux during the smelting of the precipitate, the formation of the matte, and a shorter crucible life. The results show that pH has a significant effect on the removal efficiency of zinc and copper cyanide ions. The optimal pH range was determined to be 3-4, and the removal efficiency of zinc and copper cyanide ions was up to 99%.

  4. PROCESS USING POTASSIUM LANTHANUM SULFATE FOR FORMING A CARRIER PRECIPITATE FOR PLUTONIUM VALUES

    Science.gov (United States)

    Angerman, A.A.

    1958-10-21

    A process is presented for recovering plutonium values in an oxidation state not greater than +4 from fluoride-soluble fission products. The process consists of adding to an aqueous acidic solution of such plutonium values a crystalline potassium lanthanum sulfate precipitate which carries the plutonium values from the solution.

  5. Conceptual design of a novel CO2 capture process based on precipitating amino acid solvents

    NARCIS (Netherlands)

    Sanchez Fernandez, E.; Heffernan, K.; Ham, L.V. van der; Linders, M.J.G.; Eggink, E.; Schrama, F.N.H.; Brilman, D.W.F.; Goetheer, E.L.V.; Vlugt, T.J.H.

    2013-01-01

    Amino acid salt based solvents can be used for CO2 removal from flue gas in a conventional absorption-thermal desorption process. Recently, new process concepts have been developed based on the precipitation of the amino acid zwitterion species during the absorption of CO2. In this work, a new

  6. Orographic Impacts on Liquid and Ice-Phase Precipitation Processes during OLYMPEX

    Science.gov (United States)

    Petersen, W. A.; Hunzinger, A.; Gatlin, P. N.; Wolff, D. B.

    2017-12-01

    The Global Precipitation Measurement (GPM) mission Olympic Mountains Experiment (OLYMPEX) focused on physical validation of GPM products in cold-season, mid-latitude frontal precipitation occurring over the Olympic Mountains of Washington State. Herein, we use data collected by the NASA S-band polarimetric radar (NPOL) to quantify and examine ice (IWP), liquid (LWP) and total water paths (TWP) relative to surface precipitation rates and column hydrometeor types for several cases occurring in different synoptic and/or Froude number regimes. These quantities are compared to coincident precipitation properties measured or estimated by GPM's Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR). Because ice scattering is the dominant radiometric signature used by the GMI for estimating precipitation over land, and because the DPR is greatly affected by ground clutter in the lowest 1 - 2 km above ground, measurement limitations combined with orographic forcing may impact the degree to which DPR and/or GMI algorithms are able to adequately observe and estimate precipitation over and around orography.Preliminary case results suggest: 1) as expected, the Olympic Mountains force robust enhancements in the liquid and ice microphysical processes on windward slopes, especially in atmospheric river events; 2) localized orographic enhancements alter the balance of liquid and frozen precipitation contributions (IWP/TWP, LWP/TWP) to near surface rain rate, and for two cases examined thus far the balance seems to be sensitive to flow direction at specific intersections with the terrain orientation; and 3) GPM measurement limitations related to the depth of surface clutter impact for the DPR, and degree to which ice processes are coupled to the orographic rainfall process (DPR and GMI), especially along windward mountain slopes, may constrain the ability of retrieval algorithms to properly estimate near-surface precipitation quantities over complex terrain. Ongoing

  7. Predictive modelling of Fe(III) precipitation in iron removal process for bioleaching circuits.

    Science.gov (United States)

    Nurmi, Pauliina; Ozkaya, Bestamin; Kaksonen, Anna H; Tuovinen, Olli H; Puhakka, Jaakko A

    2010-05-01

    In this study, the applicability of three modelling approaches was determined in an effort to describe complex relationships between process parameters and to predict the performance of an integrated process, which consisted of a fluidized bed bioreactor for Fe(3+) regeneration and a gravity settler for precipitative iron removal. Self-organizing maps were used to visually evaluate the associations between variables prior to the comparison of two different modelling methods, the multiple regression modelling and artificial neural network (ANN) modelling, for predicting Fe(III) precipitation. With the ANN model, an excellent match between the predicted and measured data was obtained (R (2) = 0.97). The best-fitting regression model also gave a good fit (R (2) = 0.87). This study demonstrates that ANNs and regression models are robust tools for predicting iron precipitation in the integrated process and can thus be used in the management of such systems.

  8. CSER 00-003: Criticality Safety Evaluation report for PFP Magnesium Hydroxide Precipitation Process for Plutonium Stabilization Glovebox 3

    International Nuclear Information System (INIS)

    LAN, J.S.

    2000-01-01

    This Criticality Safety Evaluation Report analyzes the stabilization of plutonium/uranium solutions in Glovebox 3 using the magnesium hydroxide precipitation process at PFP. The process covered are the receipt of diluted plutonium solutions into three precipitation tanks, the precipitation of plutonium from the solution, the filtering of the plutonium precipitate from the solution, the scraping of the precipitate from the filter into boats, and the initial drying of the precipitated slurry on a hot plate. A batch (up to 2.5 kg) is brought into the glovebox as plutonium nitrate, processed, and is then removed in boats for further processing. This CSER establishes limits for the magnesium hydroxide precipitation process in Glovebox 3 to maintain criticality safety while handling fissionable material

  9. Microstructural Evolution and the Precipitation Behavior in X90 Linepipe Steel During Isothermal Processing

    Science.gov (United States)

    Tian, Y.; Wang, H. T.; Wang, Z. D.; Misra, R. D. K.; Wang, G. D.

    2018-03-01

    Thermomechanical controlled processing of 560-MPa (X90) linepipe steel was simulated in the laboratory using a thermomechanical simulator to study the microstructural evolution and precipitation behavior during isothermal holding. The results indicated that martensite was obtained when the steels were isothermally held for 5 s at 700 °C. Subsequently, granular bainite and acicular ferrite transformation occurred with increased holding time. Different amount of polygonal ferrite formed after isothermally holding for 600-3600 s. Pearlite nucleated after isothermally holding for 3600 s. Precipitation occurred after isothermal holding for 5 s and continuous precipitation occurred at grain boundaries after isothermally holding for 600 s. After isothermally holding for 3600 s, large Nb/Ti carbide precipitated. The presence of MX-type precipitates was confirmed by diffraction pattern. The interphase precipitation (IP) occurred between 5 and 30 s. Maximum hardness was obtained after isothermally holding for 600 s when IP occurred and rapidly decreased to a low value, mainly because polygonal ferrite dominated the microstructure after isothermally holding for 3600 s.

  10. Precipitate hydrolysis process for the removal of organic compounds from nuclear waste slurries

    Science.gov (United States)

    Doherty, J.P.; Marek, J.C.

    1987-02-25

    A process for removing organic compounds from a nuclear waste slurry comprising reacting a mixture of radioactive waste precipitate slurry and an acid in the presence of a catalytically effective amount of a copper(II) catalyst whereby the organic compounds in the precipitate slurry are hydrolyzed to form volatile organic compounds which are separated from the reacting mixture. The resulting waste slurry, containing less than 10 percent of the original organic compounds, is subsequently blended with high level radioactive sludge land transferred to a vitrification facility for processing into borosilicate glass for long-term storage. 2 figs., 3 tabs.

  11. Acidic precipitation. Volume 4: Soils, aquatic processes, and lake acidification. Advances in environmental science

    Energy Technology Data Exchange (ETDEWEB)

    Norton, S.A.; Lindberg, S.E.; Page, A.L. (eds.)

    1990-01-01

    Acidic precipitation and its effects have been the focus of intense research for over two decades. Recently, research has focused on a greater understanding of dose-response relationships between atmospheric loading of acidifying material and lake acidity. This volume of the subseries Acidic Precipitation emphasizes acid neutralizing processes and the capacity of terrestrial and aquatic systems to assimilate acidifying substances and, conversely, the ability of systems to recover after acid loading diminishes. Eight chapters have been processed separately for inclusion in the appropriate data bases.

  12. Optimization of process parameters in precipitation for consistent quality UO{sub 2} powder production

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, S.K.; Reddy, A.L.V.; Venkataswamy, J.; Misra, M.; Setty, D.S.; Sheela, S.; Saibaba, N., E-mail: misra@nfc.gov.in [Nuclear Fuel Complex, Hyderabad (India)

    2013-07-01

    Nuclear reactor grade natural uranium dioxide powder is being produced through precipitation route, which is further processed before converting into sintered pellets used in the fabrication of PHWR fuel assemblies of 220 and 540 MWe type reactors. The process of precipitating Uranyl Nitrate Pure Solution (UNPS) is an important step in the UO{sub 2} powder production line, where in soluble uranium is transformed into solid form of Ammonium Uranate (AU), which in turn reflects and decides the powder characteristics. Precipitation of UNPS with vapour ammonia is being carried out in semi batch process and process parameters like ammonia flow rate, temperature, concentration of UNPS and free acidity of UNPS are very critical and decides the UO{sub 2} powder quality. Variation in these critical parameters influences powder characteristics, which in turn influences the sinterability of UO{sub 2} powder. In order to get consistent powder quality and sinterability the critical parameter like ammonia flow rate during precipitation is studied, optimized and validated. The critical process parameters are controlled through PLC based automated on-line data acquisition systems for achieving consistent powder quality with increased recovery and production. The present paper covers optimization of process parameters and powder characteristics. (author)

  13. Optimization of process parameters in precipitation for consistent quality UO2 powder production

    International Nuclear Information System (INIS)

    Tiwari, S.K.; Reddy, A.L.V.; Venkataswamy, J.; Misra, M.; Setty, D.S.; Sheela, S.; Saibaba, N.

    2013-01-01

    Nuclear reactor grade natural uranium dioxide powder is being produced through precipitation route, which is further processed before converting into sintered pellets used in the fabrication of PHWR fuel assemblies of 220 and 540 MWe type reactors. The process of precipitating Uranyl Nitrate Pure Solution (UNPS) is an important step in the UO 2 powder production line, where in soluble uranium is transformed into solid form of Ammonium Uranate (AU), which in turn reflects and decides the powder characteristics. Precipitation of UNPS with vapour ammonia is being carried out in semi batch process and process parameters like ammonia flow rate, temperature, concentration of UNPS and free acidity of UNPS are very critical and decides the UO 2 powder quality. Variation in these critical parameters influences powder characteristics, which in turn influences the sinterability of UO 2 powder. In order to get consistent powder quality and sinterability the critical parameter like ammonia flow rate during precipitation is studied, optimized and validated. The critical process parameters are controlled through PLC based automated on-line data acquisition systems for achieving consistent powder quality with increased recovery and production. The present paper covers optimization of process parameters and powder characteristics. (author)

  14. Investigation of Cyanide Removal from Aqueous Solution Using Precipitation Process (FeCl3

    Directory of Open Access Journals (Sweden)

    A. Jonidi Jafari

    2013-02-01

    Full Text Available Background and Objectives: Cyanide is a toxic pollutant that is can be discharged from different industries such as iron and steel industry, coal mining and metal plating. Presence of this toxin in water and wastewater is a serious hazard and lead to undesirable effects on both the environment and human. Thus, its concentration control is essential for human health. The aim of this study was investigation of Cyanide Removal from aqueous solution using precipitation process (FeCl3. Material and Methods: This study is an experimental study in lab scale that was carried out in a batch system by jartest. Variations of this study including pH, FeCl3 concentration, reaction time and desired concentration of cyanide were investigated. Data were analyzed using Excel (version 2007 software. Results: The results of this research were showed that Cyanide with initial concentration of 10 mg/l in precipitation process was removed by 40% (conditions pH=90, FeCl3=0.4 g/l and the time 60 minutes. Also, the precipitation process efficiency to cyanide removal decreased of 40 to 23%, by increasing of the initial cyanide concentration of 10 to 15 mg/l. Conclusion: Precipitation process can be considered as a suitable alternative for recovery of cyanide to be re-used. Although, this process has limitations for treat total cyanide to environmental standards level. So, it is better be used in combination with other processes of these contaminants removal.

  15. Prediction of ferric iron precipitation in bioleaching process using partial least squares and artificial neural network

    Directory of Open Access Journals (Sweden)

    Golmohammadi Hassan

    2013-01-01

    Full Text Available A quantitative structure-property relationship (QSPR study based on partial least squares (PLS and artificial neural network (ANN was developed for the prediction of ferric iron precipitation in bioleaching process. The leaching temperature, initial pH, oxidation/reduction potential (ORP, ferrous concentration and particle size of ore were used as inputs to the network. The output of the model was ferric iron precipitation. The optimal condition of the neural network was obtained by adjusting various parameters by trial-and-error. After optimization and training of the network according to back-propagation algorithm, a 5-5-1 neural network was generated for prediction of ferric iron precipitation. The root mean square error for the neural network calculated ferric iron precipitation for training, prediction and validation set are 32.860, 40.739 and 35.890, respectively, which are smaller than those obtained by PLS model (180.972, 165.047 and 149.950, respectively. Results obtained reveal the reliability and good predictivity of neural network model for the prediction of ferric iron precipitation in bioleaching process.

  16. Separation and purification of uranium product from thorium in thorex process by precipitation technique

    International Nuclear Information System (INIS)

    Ramanujam, A.; Dhami, P.S.; Gopalakrishnan, V.; Mukherjee, A.; Dhumwad, R.K.

    1989-01-01

    A sequential precipitation technique is reported for the separation of uranium and thorium present in the uranium product stream of a single cycle 5 per cent TBP Thorex Process. It involves the precipitation of thorium as oxalate in 1M HNO 3 medium at 60-70degC and after filtration, precipitation of uranium as ammonium diuranate at 80-90degC from the oxalate supernatant. This technique has several advantages over the ion-exchange process normally used for treating these products. In order to meet the varying feed conditions, this method has been tested for feeds containing 10 g/1 uranium and 1-50 g/1 thorium in 1-6M HNO 3 . Various parameters like feed acidities, uranium and thorium concentrations, excess oxalic acid concentrations in the oxalate supernatant, precipitation temperatures, precipitate wash volumes etc. have been optimised to obtain more than 99 per cent recovery of thorium and uranium as their oxides with less than 50 ppm uranium losses to ammonium diuranate filtrate. The distribution patterns of different fission products and stainless steel corrosion products during various steps of this procedure have also been studied. For simulating the actual Thorex plant scale operation, experiments have been conducted with 25g and 100g lots of uranium per batch. (author). 6 tabs., 8 figs., 22 refs

  17. Asphaltene precipitation and its effects on the vapour extraction (VAPEX) heavy oil recovery process

    Energy Technology Data Exchange (ETDEWEB)

    Luo, P.; Wang, X.; Gu, Y. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Regina Univ., SK (Canada). Petroleum Technology Research Centre; Zhang, H. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Core Laboratories Canada Ltd., Calgary, AB (Canada); Moghadam, L. [Fekete Associates Inc., Calgary, AB (Canada)

    2008-10-15

    One of the most important physical phenomena during the solvent vapour extraction (VAPEX) of heavy oil recovery is asphaltene precipitation. After the asphaltene precipitation occurs, the produced heavy oil is deasphalted in-situ, resulting in a lower viscosity and better quality. However, precipitated asphaltenes may plug some small pores of the reservoir formation, thus reducing its permeability. This paper examined the effects of three operating factors on the asphaltene precipitation during the VAPEX process, notably solvent type; operating pressure; and sand-pack permeability. Eight VAPEX tests were conducted to recover two different Lloydminster heavy oil samples from a rectangular sand-packed physical model with a butane mixture and propane as the respective solvents. The accumulative heavy oil and solvent production from the physical model were measured in the entire VAPEX process. The paper described the materials, experimental set-up, and experimental preparation. The VAPEX test was also explained. Results were presented for sand consolidation; solvent effect; pressure effect; and permeability effect. It was concluded that when the extracting solvent is in a liquid-gas state, asphaltene precipitation occurs and leads to in-situ deasphalting. 15 refs., 3 tabs., 6 figs.

  18. Studies of some phenomena in control engineering projects - With application to precipitation processes

    Energy Technology Data Exchange (ETDEWEB)

    Stoele-Hansen, Kjell

    1998-12-31

    This thesis deals with the life-cycle of a control engineering project and some phenomena encountered in such projects. Different types of control strategies are discussed and an attempt is made to classify them into categories. Some case projects are presented and forms the basis for discussing the individual`s role in a change project. Further conditions for successful implementation of new control strategies are discussed in general, but also conditions for successful implementation of new control strategies at a process section of a nickel work. Procedures for implementing new control strategies are treated and some remarks are made about operation of control strategies. An introduction is given to the modelling of precipitation in pH systems and different model formulations are discused. The modelling of pH controlled precipitations is discussed in general. A variety of dynamic models, ranging from complex to simple, are proposed and discussed. A rigorous dynamic nonlinear mechanistic model of a precipitation reactor is developed. It is based on the theory of reaction invariants and variants. The model is verified against real process data. The dynamics and characteristics of the precipitation reactor are analysed and some remarks are made with respect to controllability. A new strategy for pH control is proposed. A new model based strategy for controlling the precipitation reactions is also proposed. 93 refs., 63 figs., 10 tabs.

  19. Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

    OpenAIRE

    Górka J.

    2017-01-01

    This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by...

  20. Optimization Recovery of Yttrium Oxide in Precipitation, Extraction, and Stripping Process

    Science.gov (United States)

    Perwira, N. I.; Basuki, K. T.; Biyantoro, D.; Effendy, N.

    2018-04-01

    Yttrium oxide can be used as a dopant control rod of nuclear reactors in YSH material and superconductors. Yttrium oxide is obtained in the Xenotime mineral derived from byproduct of tin mining PT Timah Bangka which contain rare earth elements (REE) dominant Y, Dy, and Gd whose content respectively about 29.53%, 7.76%, and 2.58%. Both usage in the field of nuclear and non-nuclear science and technology is need to pure from the impurities. The presence of impurities in the yttrium oxide may affect the characteristic of the material and the efficiency of its use. Thus it needs to be separated by precipitation and extraction-stripping and calcination in the making of the oxide. However, to obtain higher levels of Yttrium oxide, it is necessary to determine the optimum conditions for its separation. The purpose of this research was to determine the optimum pH of precipitation, determine acid media and concentration optimum in extraction and stripping process and determine the efficiency of the separation of Y from REE concentrate. This research was conducted with pH variation in the precipitation process that pHs were 4 - 8, the difference of acid media for the extraction process, i.e., HNO3, HCl and H2SO4 with each concentration of 0,5 M; 1 M; 1,5 M; and 2 M and for stripping process were HNO3, HCl, and H2SO4 with each concentration of 1 M; 2M; and 3 M. Based on the result, the optimum pH of precipitation process was 6,5, the optimumacid media was HNO3 0,5 M, and for stripping process media was HNO3 3 M. The efficiency of precipitation process at pH 6,5 was 69,53 %, extraction process was 96.39% and stripping process was 4,50%. The separation process from precipitation to extraction had increased the purity and the highest efficiency recovery of Y was in the extraction process and obtained Y2O3 purer compared to the feed with the Y2O3 content of 92.87%.

  1. Data processing for potentiometric precipitation titration of mixtures of isovalent ions by linear regression analysis

    International Nuclear Information System (INIS)

    Mar'yanov, B.M.; Shumar, S.V.; Gavrilenko, M.A.

    1994-01-01

    A method for the computer processing of the curves of potentiometric differential titration using the precipitation reactions is developed. This method is based on transformation of the titration curve into a line of multiphase regression, whose parameters determine the equivalence points and the solubility products of the formed precipitates. The computational algorithm is tested using experimental curves for the titration of solutions containing Hg(2) and Cd(2) by the solution of sodium diethyldithiocarbamate. The random errors (RSD) for the titration of 1x10 -4 M solutions are in the range of 3-6%. 7 refs.; 2 figs.; 1 tab

  2. Fine-scale precipitation and mechanical properties of thin slab processed titanium-niobium bearing high strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Z. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Misra, R.D.K., E-mail: dmisra@louisiana.edu [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); O' Malley, R. [Nucor Steel Decatur, LLC, 4301 Iverson Blvd., Trinity, AL 35673 (United States); Jansto, S.J. [CBMM-Reference Metals Company, 1000 Old Pond Road, Bridgeville, PA 15017 (United States)

    2011-08-25

    Highlights: {yields} Precipitation and mechanical behavior of Ti-Nb and Ti-Nb-Mo-V steels were elucidated. {yields} Distribution of precipitates was analyzed with microscopy and diffraction pattern. {yields} During austenite-ferrite transformation, interface precipitation of NbC was observed. {yields} Epitaxial precipitation of NbC on TiC surface results in mixed precipitates Ti(Nb)C. - Abstract: We describe here the precipitation behavior and mechanical properties of 560 MPa Ti-Nb and 770 MPa Ti-Nb-Mo-V steels. The precipitation characteristics were analyzed in terms of chemistry and size distribution of precipitates, with particular focus on the crystallography of precipitates through an analysis of electron diffraction patterns. In addition to pure carbides (NbC, TiC, Mo{sub 2}C, and VC), Nb containing titanium-rich carbides were also observed. These precipitates were of a size range of 4-20 nm. The mechanism of formation of these Ti-rich niobium containing carbides is postulated to involve epitaxial nucleation of NbC on previously precipitated TiC. Interface precipitation of NbC was an interesting observation in compact strip processing which is characterized by an orientation relationship of [0 0 1]{sub NbC}//[0 0 1]{sub {alpha}-Fe}, implying that the precipitation of NbC occurred during austenite-ferrite transformation.

  3. Fine-scale precipitation and mechanical properties of thin slab processed titanium-niobium bearing high strength steels

    International Nuclear Information System (INIS)

    Jia, Z.; Misra, R.D.K.; O'Malley, R.; Jansto, S.J.

    2011-01-01

    Highlights: → Precipitation and mechanical behavior of Ti-Nb and Ti-Nb-Mo-V steels were elucidated. → Distribution of precipitates was analyzed with microscopy and diffraction pattern. → During austenite-ferrite transformation, interface precipitation of NbC was observed. → Epitaxial precipitation of NbC on TiC surface results in mixed precipitates Ti(Nb)C. - Abstract: We describe here the precipitation behavior and mechanical properties of 560 MPa Ti-Nb and 770 MPa Ti-Nb-Mo-V steels. The precipitation characteristics were analyzed in terms of chemistry and size distribution of precipitates, with particular focus on the crystallography of precipitates through an analysis of electron diffraction patterns. In addition to pure carbides (NbC, TiC, Mo 2 C, and VC), Nb containing titanium-rich carbides were also observed. These precipitates were of a size range of 4-20 nm. The mechanism of formation of these Ti-rich niobium containing carbides is postulated to involve epitaxial nucleation of NbC on previously precipitated TiC. Interface precipitation of NbC was an interesting observation in compact strip processing which is characterized by an orientation relationship of [0 0 1] NbC //[0 0 1] α-Fe , implying that the precipitation of NbC occurred during austenite-ferrite transformation.

  4. Detection of non-stationarity in precipitation extremes using a max-stable process model

    Science.gov (United States)

    Westra, S.; Sisson, S.

    2011-12-01

    The question of how extreme precipitation will change under a future climate represents an urgent research problem, not least because of the significant societal impacts that would result from an increase in precipitation-induced flooding. To better constrain future projections, an important line of evidence comes from statistical assessments of change to extreme precipitation in the observational record, as a significant amount of warming since pre-industrial times has already taken place. In this study we address this problem by applying a max-stable process model to evaluate whether extreme precipitation at sub-daily and daily timescales has changed at various locations around Australia. This max-stable process approach, which was developed to simulate spatial fields comprising observations from multiple point locations, significantly increases the precision of a statistical inference compared to standard univariate methods. Applying the technique to a field of annual maxima derived from 30 sub-daily gauges in east Australia from 1965 to 2005, we find a statistically significant increase of 18% for 6-minute rainfall over this period, with smaller increases for longer duration events. We also find an increase of 5.6% and 22.5% per degree of Australian land surface temperature and global sea surface temperature at 6-minute durations, respectively, again with smaller scaling relationships for longer durations. In contrast, limited change could be observed in daily rainfall at most locations, with the exception of a statistically significant decline of 7.4% per degree land surface temperature in southwest Western Australia. These results suggest both the importance of better understanding changes to precipitation at the sub-daily timescale, as well as the need to more precisely simulate temporal variability by accounting for the spatial nature of precipitation in any statistical model.

  5. Spring precipitation in inland Iberia: land-atmosphere interactions and recycling and amplification processes.

    Science.gov (United States)

    Rios-Entenza, A.; Miguez-Macho, G.

    2012-04-01

    Inland Iberia, the highest peak of rainfall occurs in May, being critical for agriculture in large water-limited areas. We investigate here the role of the soil moisture - precipitation feedback in the intensification of the water cycle in spring and in the aforementioned maximum of precipitation in the interior of the Iberian Peninsula. We conducted paired, high-resolution simulations with the WRF-ARW model, using a nested grid that covers the Iberian Peninsula at 5km resolution. Eleven months of May (from May 2000 to May 2010) and eleven months of January (from January 2000 to January 2010) were selected. For each month, we performed two simulations: a control one, where all land-atmosphere fluxes are normally set up, and the corresponding experiment, where evapotranspired water over land in the nested domain is not incorporated into the atmosphere, although the corresponding latent heat flux is considered in the surface energy budget. As expected, precipitation is higher in the control runs with respect to the experiments and, furthermore, this fraction of extra rainfall substantially exceeds the value of the analytical recycling ratio. This suggests that amplification processes, and not only direct recycling, may play an important role in the maximum of precipitation observed in the Iberian spring. We estimated the amplification effect to be as large as the recycling with calculations using analytical methods of separation of both contributions. We also develop here a procedure to quantify the amplification impact using the no-ET experiment and results confirm those obtained analytically. These results suggest that in the Iberian spring, under favourable synoptic conditions and given a small supply of external moisture that triggers large-scale convection, land-atmosphere interactions can intensify and sustain convective processes in time. Thus there is a large impact of local land-surface fluxes on precipitation and that alterations of anthropogenic nature can

  6. Quantitative analysis of precipitation over Fukushima to understand the wet deposition process in March 2011

    Science.gov (United States)

    Yatagai, A.; Onda, Y.; Watanabe, A.

    2012-04-01

    The Great East Japan Earthquake caused a severe accident at the Fukushima-Daiichi nuclear power plant (NPP), leading to the emission of large amounts of radioactive pollutants into the environment. The transport and diffusion of these radioactive pollutants in the atmosphere caused a disaster for residents in and around Fukushima. Studies have sought to understand the transport, diffusion, and deposition process, and to understand the movement of radioactive pollutants through the soil, vegetation, rivers, and groundwater. However, a detailed simulation and understanding of the distribution of radioactive compounds depend on a simulation of precipitation and on the information on the timing of the emission of these radioactive pollutants from the NPP. Past nuclear expansion studies have demonstrated the importance of wet deposition in distributing pollutants. Hence, this study examined the quantitative precipitation pattern in March 2011 using rain-gauge observations and X-band radar data from Fukushima University. We used the AMeDAS rain-gauge network data of 1) the Japan Meteorological Agency (1273 stations in Japan) and 2) the Water Information System (47 stations in Fukushima prefecture) and 3) the rain-gauge data of the Environmental Information Network of NTT Docomo (30 stations in Fukushima) to construct 0.05-degree mesh data using the same method used to create the APHRODITE daily grid precipitation data (Yatagai et al., 2009). Since some AMeDAS data for the coastal region were lost due to the earthquake, the complementary network of 2) and 3) yielded better precipitation estimates. The data clarified that snowfall was observed on the night of Mar 15 into the morning of Mar 16 throughout Fukushima prefecture. This had an important effect on the radioactive contamination pattern in Fukushima prefecture. The precipitation pattern itself does not show one-on-one correspondence with the contamination pattern. While the pollutants transported northeast of the

  7. Asymmetrical Responses of Ecosystem Processes to Positive Versus Negative Precipitation Extremes: a Replicated Regression Experimental Approach

    Science.gov (United States)

    Felton, A. J.; Smith, M. D.

    2016-12-01

    Heightened climatic variability due to atmospheric warming is forecast to increase the frequency and severity of climate extremes. In particular, changes to interannual variability in precipitation, characterized by increases in extreme wet and dry years, are likely to impact virtually all terrestrial ecosystem processes. However, to date experimental approaches have yet to explicitly test how ecosystem processes respond to multiple levels of climatic extremity, limiting our understanding of how ecosystems will respond to forecast increases in the magnitude of climate extremes. Here we report the results of a replicated regression experimental approach, in which we imposed 9 and 11 levels of growing season precipitation amount and extremity in mesic grassland during 2015 and 2016, respectively. Each level corresponded to a specific percentile of the long-term record, which produced a large gradient of soil moisture conditions that ranged from extreme wet to extreme dry. In both 2015 and 2016, asymptotic responses to water availability were observed for soil respiration. This asymmetry was driven in part by transitions between soil moisture versus temperature constraints on respiration as conditions became increasingly dry versus increasingly wet. In 2015, aboveground net primary production (ANPP) exhibited asymmetric responses to precipitation that largely mirrored those of soil respiration. In total, our results suggest that in this mesic ecosystem, these two carbon cycle processes were more sensitive to extreme drought than to extreme wet years. Future work will assess ANPP responses for 2016, soil nutrient supply and physiological responses of the dominant plant species. Future efforts are needed to compare our findings across a diverse array of ecosystem types, and in particular how the timing and magnitude of precipitation events may modify the response of ecosystem processes to increasing magnitudes of precipitation extremes.

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

    Science.gov (United States)

    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.

  9. An improved lightning flash rate parameterization developed from Colorado DC3 thunderstorm data for use in cloud-resolving chemical transport models

    Science.gov (United States)

    Basarab, B. M.; Rutledge, S. A.; Fuchs, B. R.

    2015-09-01

    Accurate prediction of total lightning flash rate in thunderstorms is important to improve estimates of nitrogen oxides (NOx) produced by lightning (LNOx) from the storm scale to the global scale. In this study, flash rate parameterization schemes from the literature are evaluated against observed total flash rates for a sample of 11 Colorado thunderstorms, including nine storms from the Deep Convective Clouds and Chemistry (DC3) experiment in May-June 2012. Observed flash rates were determined using an automated algorithm that clusters very high frequency radiation sources emitted by electrical breakdown in clouds and detected by the northern Colorado lightning mapping array. Existing schemes were found to inadequately predict flash rates and were updated based on observed relationships between flash rate and simple storm parameters, yielding significant improvement. The most successful updated scheme predicts flash rate based on the radar-derived mixed-phase 35 dBZ echo volume. Parameterizations based on metrics for updraft intensity were also updated but were found to be less reliable predictors of flash rate for this sample of storms. The 35 dBZ volume scheme was tested on a data set containing radar reflectivity volume information for thousands of isolated convective cells in different regions of the U.S. This scheme predicted flash rates to within 5.8% of observed flash rates on average. These results encourage the application of this scheme to larger radar data sets and its possible implementation into cloud-resolving models.

  10. Influence of Surface Processes over Africa on the Atlantic Marine ITCZ and South American Precipitation.

    Science.gov (United States)

    Hagos, Samson M.; Cook, Kerry H.

    2005-12-01

    Previous studies show that the climatological precipitation over South America, particularly the Nordeste region, is influenced by the presence of the African continent. Here the influence of African topography and surface wetness on the Atlantic marine ITCZ (AMI) and South American precipitation are investigated.Cross-equatorial flow over the Atlantic Ocean introduced by north south asymmetry in surface conditions over Africa shifts the AMI in the direction of the flow. African topography, for example, introduces an anomalous high over the southern Atlantic Ocean and a low to the north. This results in a northward migration of the AMI and dry conditions over the Nordeste region.The implications of this process on variability are then studied by analyzing the response of the AMI to soil moisture anomalies over tropical Africa. Northerly flow induced by equatorially asymmetric perturbations in soil moisture over northern tropical Africa shifts the AMI southward, increasing the climatological precipitation over northeastern South America. Flow associated with an equatorially symmetric perturbation in soil moisture, however, has a very weak cross-equatorial component and very weak influence on the AMI and South American precipitation. The sensitivity of the AMI to soil moisture perturbations over certain regions of Africa can possibly improve the skill of prediction.

  11. The coarsening process of Ge precipitates in an Al-4 wt.% Ge alloy

    Energy Technology Data Exchange (ETDEWEB)

    Deaf, G.H

    2004-05-01

    In this paper the results of a quantitative transmission electron microscopy (TEM) investigation of the precipitation process of Ge in an Al-4 wt.% Ge alloy are described. Two crystallographic orientation relationships between the irregular germanium precipitate and aluminum matrix were found to be [1 0 0]{sub Ge} || [1 1 0]{sub Al} and [1 1 4]{sub Ge} || [1 0 0]{sub Al}. The irregular germanium precipitates formed on [0 0 1]{sub Al} habit planes. The origin of the irregular shape is due to the existence of a highly anisotropic interfacial energy as well as in an isotropic growth rate along <1 1 0>{sub A1} directions. Particles sizes were determined for variety of isothermal ageing times at 348, 423 and 523 K. The coarsening of the different morphologies of Ge precipitates was found to obey Ostwald ripening kinetics. The TEM results showed that the coarsening of irregular particles was due to the interfacial coalescence between these particles. Nine different morphologies have been distinguished in the form of (i) irregular particles, (ii) spheres, (iii) hexagonal plates, (iv) rods, (v) triangular plates, (vi) laths, (vii) small tetrahedra, (viii) rectangular plates, and (ix) Lamellae shape.

  12. Kinetics of oxygen adsorption on ZnS nanoparticles synthesized by precipitation process

    Directory of Open Access Journals (Sweden)

    Ahmadi Reza

    2016-06-01

    Full Text Available ZnS nanoparticles were synthesized through a one-step precipitation process. Effect of time and temperature on the formation reaction was investigated. The synthesized samples were characterized by X-ray diffraction (XRD, ultraviolet (UV visible absorption and photoluminescence (PL spectrophotometry. Based on XRD and UV-Vis data, the particles produced at 70 °C had a mean particle size of about 5 nm. Increasing time and temperature of the synthesis reaction resulted in photoluminescence intensification. PL spectroscopy helped understanding the adsorption kinetics of oxygen on ZnS nanoparticles during the precipitation synthesis process. Fabrication of ZnS structures with appropriate oxygen adsorption capacity was suggested as a means of PL emission intensity control.

  13. The response of a simulated mesoscale convective system to increased aerosol pollution: Part I: Precipitation intensity, distribution, and efficiency

    Science.gov (United States)

    Clavner, Michal; Cotton, William R.; van den Heever, Susan C.; Saleeby, Stephen M.; Pierce, Jeffery R.

    2018-01-01

    Mesoscale Convective Systems (MCSs) are important contributors to rainfall in the High Plains of the United States and elsewhere in the world. It is therefore of interest to understand how different aerosols serving as cloud condensation nuclei (CCN) may impact the total amount, rates and spatial distribution of precipitation produced by MCSs. In this study, different aerosol concentrations and their effects on precipitation produced by an MCS are examined by simulating the 8 May 2009 "Super-Derecho" MCS using the Regional Atmospheric Modeling System (RAMS), a cloud-resolving model (CRM) with sophisticated aerosol and microphysical parameterizations. Three simulations were conducted that differed only in the initial concentration, spatial distribution, and chemical composition of aerosols. Aerosol fields were derived from the output of GEOS-Chem, a 3D chemical transport numerical model. Results from the RAMS simulations show that the total domain precipitation was not significantly affected by variations in aerosol concentrations, however, the pollution aerosols altered the precipitation characteristics. The more polluted simulations exhibited higher precipitation rates, higher bulk precipitation efficiency, a larger area with heavier precipitation, and a smaller area with lighter precipitation. These differences arose as a result of aerosols enhancing precipitation in the convective region of the MCS while suppressing precipitation from the MCS's stratiform-anvil. In the convective region, several processes likely contributed to an increase of precipitation. First, owing to the very humid environment of this storm, the enhanced amount of cloud water available to be collected overwhelmed the reduction in precipitation efficiency associated with the aerosol-induced production of smaller droplets which led to a net increase in the conversion of cloud droplets to precipitation. Second, higher aerosol concentrations led to invigoration of convective updrafts which

  14. Physicochemical Properties and In Vitro Dissolution of Spiramycin Microparticles Using the Homogenate-Antisolvent Precipitation Process

    Directory of Open Access Journals (Sweden)

    Xiaonan Zhang

    2016-12-01

    Full Text Available Due to its low bioavailability and slow dissolution rate, the micronized spiramycin powder was thus prepared by the homogenate-antisolvent precipitation (HAP process. The optimum micronization conditions of the HAP process were found to be as follows: precipitation temperature of 4.6 °C, precipitation time of 10 min, spiramycin concentration of 20 mg/mL, dripping speed of the added solvent into the antisolvent of 44 mL/h, antisolvent (water to solvent (dimethyl sulfide (DMSO volume ratio of 7:1, and shear rate of 5000 rpm. With this HAP process, the mean particle size was 228.36 ± 3.99 nm. The micronized spiramycin was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, high-performance liquid chromatography, and gas chromatograph analyses. In comparison with the raw drug, the chemical structure of micronized spiramycin was not changed. The dissolution rate experiments showed that the dissolution rate of the spiramycin was significantly increased after micronization.

  15. Study of benzene release from Savannah River in-tank precipitation process slurry simulant

    International Nuclear Information System (INIS)

    Rappe, K.G.; Gauglitz, P.A.

    1998-08-01

    At the Savannah River Site, the in-tank precipitation (ITP) process uses sodium tetraphenylborate (NaTPB) to precipitate radioactive cesium from alkaline wastes. During this process, potassium is also precipitated to form 4-wt% KTPB/CsTPB slurry. Residual NaTPB decomposes to form benzene, which is retained by the waste slurry. The retained benzene is also readily released from the waste during subsequent waste processing. While the release of benzene certainly poses flammability and toxicological safety concerns, the magnitude of the hazard depends on the rate of release. Currently, the mechanisms controlling the benzene release rates are not well understood, and predictive models for estimating benzene release rates are not available. The overall purpose of this study is to obtain quantitative measurements of benzene release rates from a series of ITP slurry simulants. This information will become a basis for developing a quantitative mechanistic model of benzene release rates. The transient benzene release rate was measured from the surface of various ITP slurry (solution) samples mixed with benzene. The benzene release rate was determined by continuously purging the headspace of a sealed sample vessel with an inert gas (nitrogen) and analyzing that purged headspace vapor for benzene every minute

  16. Magnetic Field Effects on CaCO3 Precipitation Process in Hard Water

    Directory of Open Access Journals (Sweden)

    Nelson Saksono

    2010-10-01

    Full Text Available Magnetic treatment is applied as physical water treatment for scale prevention especially CaCO3, from hard water in piping equipment by reducing its hardness.Na2CO3 and CaCl2 solution sample was used in to investigate the magnetic fields influence on the formation of particle of CaCO3. By changing the strength of magnetic fields, exposure time and concentration of samples solution, this study presents quantitative results of total scale deposit, total precipitated CaCO3 and morphology of the deposit. This research was run by comparing magnetically and non-magnetically treated  samples. The results showed an increase of deposits formation rate and total number of precipitated CaCO3 of magnetically treated samples. The increase of concentration solution sample will also raised the deposit under magnetic  field. Microscope images showed a greater number but smaller size of CaCO3 deposits form in magnetically treated samples, and aggregation during the processes. X-ray diffraction (XRD analysis showed that magnetically samples were dominated by calcite. But, there was a significant decrease of calcite’s peak intensities from magnetized  samples that indicated the decrease of the amount of calcite and an increase of total amorphous of deposits. This result  showed that magnetization of hard water leaded to the decreasing of ion Ca2+ due to the increasing of total CaCO3 precipitation process.

  17. Comment on 'Modeling of Convective-Stratiform Precipitation Processes: Sensitivity to Partitioning Methods' by Matthias Steiner

    Science.gov (United States)

    Lang, Steve; Tao, W.-K.; Simpson, J.; Ferrier, B.

    2003-01-01

    Despite the obvious notion that the presence of hail or graupel is a good indication of convection, the model results show this does not provide an objective benchmark partly due to the unrealistic presence of small amounts of hail or graupel throughout the anvil in the model but mainly because of the significant amounts of hail or graupel, especially in the tropical TOGA COARE simulation, in the transition zone. Without use of a "transition" category, it is open to debate as how this region should best be defined, as stratiform or as convective. So, the presence of significant hail or graupel contents in this zone significantly degrades its use an objective benchmark for convection. The separation algorithm comparison was done in the context of a cloud-resolving model. These models are widely used and serve a variety of purposes especially with regard to retrieving information that cannot be directly measured by providing synthetic data sets that are consistent and complete. Separation algorithms are regularly applied in these models. However, as with any modeling system, these types 'of models are constantly being improved to overcome any known deficiencies and make them more accurate representations of observed systems. The presence of hail and graupel in the anvil and the bias towards heavy rainfall rates are two such examples of areas that need improvement. Since, both of these can effect the perceived performance of the separation algorithms, the Lang et al. (2003) study did not want to overstate the relative performance of any specific algorithms.

  18. Doubly stochastic Poisson process models for precipitation at fine time-scales

    Science.gov (United States)

    Ramesh, Nadarajah I.; Onof, Christian; Xie, Dichao

    2012-09-01

    This paper considers a class of stochastic point process models, based on doubly stochastic Poisson processes, in the modelling of rainfall. We examine the application of this class of models, a neglected alternative to the widely-known Poisson cluster models, in the analysis of fine time-scale rainfall intensity. These models are mainly used to analyse tipping-bucket raingauge data from a single site but an extension to multiple sites is illustrated which reveals the potential of this class of models to study the temporal and spatial variability of precipitation at fine time-scales.

  19. A Family of Poisson Processes for Use in Stochastic Models of Precipitation

    Science.gov (United States)

    Penland, C.

    2013-12-01

    Both modified Poisson processes and compound Poisson processes can be relevant to stochastic parameterization of precipitation. This presentation compares the dynamical properties of these systems and discusses the physical situations in which each might be appropriate. If the parameters describing either class of systems originate in hydrodynamics, then proper consideration of stochastic calculus is required during numerical implementation of the parameterization. It is shown here that an improper numerical treatment can have severe implications for estimating rainfall distributions, particularly in the tails of the distributions and, thus, on the frequency of extreme events.

  20. Performance Assessment of Spatial Interpolation of Precipitation for Hydrological Process Simulation in the Three Gorges Basin

    Directory of Open Access Journals (Sweden)

    Meiling Cheng

    2017-11-01

    Full Text Available Accurate assessment of spatial and temporal precipitation is crucial for simulating hydrological processes in basins, but is challenging due to insufficient rain gauges. Our study aims to analyze different precipitation interpolation schemes and their performances in runoff simulation during light and heavy rain periods. In particular, combinations of different interpolation estimates are explored and their performances in runoff simulation are discussed. The study was carried out in the Pengxi River basin of the Three Gorges Basin. Precipitation data from 16 rain gauges were interpolated using the Thiessen Polygon (TP, Inverse Distance Weighted (IDW, and Co-Kriging (CK methods. Results showed that streamflow predictions employing CK inputs demonstrated the best performance in the whole process, in terms of the Nash–Sutcliffe Coefficient (NSE, the coefficient of determination (R2, and the Root Mean Square Error (RMSE indices. The TP, IDW, and CK methods showed good performance in the heavy rain period but poor performance in the light rain period compared with the default method (least sophisticated nearest neighbor technique in Soil and Water Assessment Tool (SWAT. Furthermore, the correlation between the dynamic weight of one method and its performance during runoff simulation followed a parabolic function. The combination of CK and TP achieved a better performance in decreasing the largest and lowest absolute errors compared to any single method, but the IDW method outperformed all methods in terms of the median absolute error. However, it is clear from our findings that interpolation methods should be chosen depending on the amount of precipitation, adaptability of the method, and accuracy of the estimate in different rain periods.

  1. The large-scale process of microbial carbonate precipitation for nickel remediation from an industrial soil.

    Science.gov (United States)

    Zhu, Xuejiao; Li, Weila; Zhan, Lu; Huang, Minsheng; Zhang, Qiuzhuo; Achal, Varenyam

    2016-12-01

    Microbial carbonate precipitation is known as an efficient process for the remediation of heavy metals from contaminated soils. In the present study, a urease positive bacterial isolate, identified as Bacillus cereus NS4 through 16S rDNA sequencing, was utilized on a large scale to remove nickel from industrial soil contaminated by the battery industry. The soil was highly contaminated with an initial total nickel concentration of approximately 900 mg kg -1 . The soluble-exchangeable fraction was reduced to 38 mg kg -1 after treatment. The primary objective of metal stabilization was achieved by reducing the bioavailability through immobilizing the nickel in the urease-driven carbonate precipitation. The nickel removal in the soils contributed to the transformation of nickel from mobile species into stable biominerals identified as calcite, vaterite, aragonite and nickelous carbonate when analyzed under XRD. It was proven that during precipitation of calcite, Ni 2+ with an ion radius close to Ca 2+ was incorporated into the CaCO 3 crystal. The biominerals were also characterized by using SEM-EDS to observe the crystal shape and Raman-FTIR spectroscopy to predict responsible bonding during bioremediation with respect to Ni immobilization. The electronic structure and chemical-state information of the detected elements during MICP bioremediation process was studied by XPS. This is the first study in which microbial carbonate precipitation was used for the large-scale remediation of metal-contaminated industrial soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Nitrogen deposition in precipitation to a monsoon-affected eutrophic embayment: Fluxes, sources, and processes

    Science.gov (United States)

    Wu, Yunchao; Zhang, Jingping; Liu, Songlin; Jiang, Zhijian; Arbi, Iman; Huang, Xiaoping; Macreadie, Peter Ian

    2018-06-01

    Daya Bay in the South China Sea (SCS) has experienced rapid nitrogen pollution and intensified eutrophication in the past decade due to economic development. Here, we estimated the deposition fluxes of nitrogenous species, clarified the contribution of nitrogen from precipitation and measured ions and isotopic composition (δ15N and δ18O) of nitrate in precipitation in one year period to trace its sources and formation processes among different seasons. We found that the deposition fluxes of total dissolved nitrogen (TDN), NO3-, NH4+, NO2-, and dissolved organic nitrogen (DON) to Daya Bay were 132.5, 64.4 17.5, 1.0, 49.6 mmol m-2•yr-1, respectively. DON was a significant contributor to nitrogen deposition (37% of TDN), and NO3- accounted for 78% of the DIN in precipitation. The nitrogen deposition fluxes were higher in spring and summer, and lower in winter. Nitrogen from precipitation contributed nearly 38% of the total input of nitrogen (point sources input and dry and wet deposition) in Daya Bay. The δ15N-NO3- abundance, ion compositions, and air mass backward trajectories implicated that coal combustion, vehicle exhausts, and dust from mainland China delivered by northeast monsoon were the main sources in winter, while fossil fuel combustion (coal combustion and vehicle exhausts) and dust from PRD and southeast Asia transported by southwest monsoon were the main sources in spring; marine sources, vehicle exhausts and lightning could be the potential sources in summer. δ18O results showed that OH pathway was dominant in the chemical formation process of nitrate in summer, while N2O5+ DMS/HC pathways in winter and spring.

  3. Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2011-12-01

    Full Text Available Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the effects of aerosols on cloud processes, precipitation, and lightning activity, a cloud resolving – Weather Research and Forecasting (CR-WRF model with a two-moment bulk microphysical scheme is employed to simulate a mesoscale convective system occurring on 28 Match 2009 in the Guangzhou megacity area. The model predicted evolutions of composite radar reflectivity and accumulated precipitation are in agreement with measurements from S-band weather radars and automatic gauge stations. The calculated lightning potential index (LPI exhibits temporal and spatial consistence with lightning flashes recorded by a local lightning detection network. Sensitivity experiments have been performed to reflect aerosol conditions representative of polluted and clean cases. The simulations suggest that precipitation and LPI are enhanced by about 16% and 50%, respectively, under the polluted aerosol condition. Our results suggest that elevated aerosol loading suppresses light and moderate precipitation (less than 25 mm per day, but enhances heavy precipitation. The responses of hydrometeors and latent heat release to different aerosol loadings reveal the physical mechanism for the precipitation and lightning enhancement in the Guangzhou megacity area, showing more efficient mixed phase processes and intensified convection under the polluted aerosol condition.

  4. Cloud Properties Simulated by a Single-Column Model. Part II: Evaluation of Cumulus Detrainment and Ice-phase Microphysics Using a Cloud Resolving Model

    Science.gov (United States)

    Luo, Yali; Krueger, Steven K.; Xu, Kuan-Man

    2005-01-01

    This paper is the second in a series in which kilometer-scale-resolving observations from the Atmospheric Radiation Measurement program and a cloud-resolving model (CRM) are used to evaluate the single-column model (SCM) version of the National Centers for Environmental Prediction Global Forecast System model. Part I demonstrated that kilometer-scale cirrus properties simulated by the SCM significantly differ from the cloud radar observations while the CRM simulation reproduced most of the cirrus properties as revealed by the observations. The present study describes an evaluation, through a comparison with the CRM, of the SCM's representation of detrainment from deep cumulus and ice-phase microphysics in an effort to better understand the findings of Part I. It is found that detrainment occurs too infrequently at a single level at a time in the SCM, although the detrainment rate averaged over the entire simulation period is somewhat comparable to that of the CRM simulation. Relatively too much detrained ice is sublimated when first detrained. Snow falls over too deep of a layer due to the assumption that snow source and sink terms exactly balance within one time step in the SCM. These characteristics in the SCM parameterizations may explain many of the differences in the cirrus properties between the SCM and the observations (or between the SCM and the CRM). A possible improvement for the SCM consists of the inclusion of multiple cumulus cloud types as in the original Arakawa-Schubert scheme, prognostically determining the stratiform cloud fraction and snow mixing ratio. This would allow better representation of the detrainment from deep convection, better coupling of the volume of detrained air with cloud fraction, and better representation of snow field.

  5. Experimentale Study of Alkaline Precipitation on Thermal Process SeaWater Desalination Condition

    International Nuclear Information System (INIS)

    Sumijanto

    2000-01-01

    The experiment of alkaline precipitation by separated method has beencarry out. Experiment took please by heating sea water simulation with eachother consist of a).142 ppm bicarbonate and 400 ppm calcium ion b). 142 ppmbicarbonate and magnesium ion at temperature 40,50,60,70,80,90,100,110 and120 o C respectively by using autoclave. Sampling has been done periodicalfor 30 minute in interval 300 minute for each temperature. The calculation ofalkaline precipitation on each step calculated through the decreasing ofcalcium and magnesium concentration with analysis by AAS. From experimentdata have the information that alkaline precipitation have been formed since40 o C. From time variable have been the information that the precipitationformed at 30 th minute rapidly. Whether at further time the increasing ofprecipitation are not significant. This phenomena can explained that at eachheating step from 40 o C bicarbonate ion be come decomposition with theresult carbonate and hydroxide ion and react with calcium and magnesium formcalcium carbonate and magnesium hydroxide. From this information could beimplemented as base for avoiding using chemical material in desalinationthermal process. (author)

  6. Synthesis of TiC/W core–shell nanoparticles by precipitate-coating process

    International Nuclear Information System (INIS)

    Xia Min; Yan Qingzhi; Xu Lei; Zhu Lingxu; Guo Hongyan; Ge Changchun

    2012-01-01

    Graphical abstract: Well-dispersed titanium carbide/tungsten (TiC/W) core-shell nanoparticles with high-purity and uniform diameters were firstly synthesized by precipitate-coating process. Such unique process suggests a new method for preparing X/W (X refers the water-insoluble nanoparticles) core-shell nanoparticles with different cores. Abstract: Well-dispersed titanium carbide/tungsten (TiC/W) core–shell nanoparticles with high-purity and uniform diameters were firstly synthesized by precipitate-coating process. The as-synthesized nanoparticles were characterized by X-ray diffraction (XRD), Filed-emission scanning electron microscope (FESEM), Transmission electron microscopy (TEM), energy dispersive spectrum (EDS). Results revealed that the as-synthesized nanoparticles possess uniform diameters about 100 nm, and high purity. TEM and the corresponding FFT images demonstrate that TiC nanoparticles were well-encapsulated by W shells. Such unique process suggests a new method for preparing X/W (X refers the water-insoluble nanoparticles) core–shell nanoparticles with different cores.

  7. Fast high-temperature consolidation of Oxide-Dispersion Strengthened (ODS) steels: process, microstructure, precipitation, properties

    International Nuclear Information System (INIS)

    Boulnat, Xavier

    2014-01-01

    This work aims to lighten the understanding of the behavior of a class of metallic materials called Oxide-Dispersion Strengthened (ODS) ferritic steels. ODS steels are produced by powder metallurgy with various steps including atomization, mechanical alloying and high-temperature consolidation. The consolidation involves the formation of nanoparticles in the steel and various evolutions of the microstructure of the material that are not fully understood. In this thesis, a novel consolidation technique assisted by electric field called 'Spark Plasma Sintering' (SPS) or 'Field-Assisted Sintering Technique' (FAST) was assessed. Excellent mechanical properties were obtained by SPS, comparable to those of conventional hot isostatic pressed (HIP) materials but with much shorter processing time. Also, a broad range of microstructures and thus of tensile strength and ductility were obtained by performing SPS on either milled or atomized powder at different temperatures. However, SPS consolidation failed to avoid heterogeneous microstructure composed of ultrafine-grained regions surrounded by micron grains despite of the rapid consolidation kinetics. A multi-scale characterization allowed to understand and model the evolution of this complex microstructure. An analytical evaluation of the contributing mechanisms can explain the appearance of the complex grain structure and its thermal stability during further heat treatments. Inhomogeneous distribution of plastic deformation in the powder is argued to be the major cause of heterogeneous recrystallization and further grain growth during hot consolidation. Even if increasing the solute content of yttrium, titanium and oxygen does not impede abnormal growth, it permits to control the fraction and the size of the retained ultrafine grains, which is a key-factor to tailor the mechanical properties. Since precipitation through grain boundary pinning plays a significant role on grain growth, a careful

  8. Detrital processing in streams exposed to acidic precipitation in the Central Appalachian Mountains

    International Nuclear Information System (INIS)

    Meegan, S.K.; Perry, S.A.; Perry, W.B.

    1996-01-01

    Continuing high rates of acidic deposition in the eastern United States may lead to long-term effects on stream communities, because sensitive catchments are continuing to lose anions and cations. A two-year study of the effects of pH and associated water chemistry variables on detrital processing in three streams with different bedrock geology in the Monongahela National Forest, West Virginia were investigated. Leaf pack processing rates and macroinvertebrate colonization and microbial biomass (ATP concentration) on the packs in the three stream were compared. It was found that macroinvertebrate and microbial communities differed both among streams that differed in their capacity to buffer the effects of acidic precipitation and among years in the same stream; these differences in biotic communities were not large enough to affect rates of leaf processing between the two years of the study, but they did significantly affect processing rates between acidic and circumneutral streams

  9. In Situ Investigation of the Iron Carbide Precipitation Process in a Fe-C-Mn-Si Q&P Steel

    Directory of Open Access Journals (Sweden)

    Sébastien Y. P. Allain

    2018-06-01

    Full Text Available Quenching and Partitioning (Q&P steels are promising candidates for automotive applications because of their lightweight potential. Their properties depend on carbon enrichment in austenite which, in turn, is strongly influenced by carbide precipitation in martensite during quenching and partitioning treatment. In this paper, by coupling in situ High Energy X-Ray Diffraction (HEXRD experiments and Transmission Electron Microscopy (TEM, we give some clarification regarding the precipitation process of iron carbides in martensite throughout the Q&P process. For the first time, precipitation kinetics was followed in real time. It was shown that precipitation starts during the reheating sequence for the steel studied. Surprisingly, the precipitated fraction remains stable all along the partitioning step at 400 °C. Furthermore, the analyses enable the conclusion that the iron carbides are most probably eta carbides. The presence of cementite was ruled out, while the presence of several epsilon carbides cannot be strictly excluded.

  10. Interim report: Study of benzene release from Savannah River in-tank precipitation process slurry simulant

    International Nuclear Information System (INIS)

    Rappe, K.G.; Gauglitz, P.A.

    1997-09-01

    At the Savannah River Site, the in-tank precipitation (ITP) process uses sodium tetraphenylborate (NaTPB) to precipitate radioactive cesium from alkaline wastes. During this process, potassium is also precipitated to form a 4-wt% KTPB/CsTPB slurry. Residual NaTPB decomposes to form benzene, which is retained by the waste slurry. The retained benzene is also readily released from the waste during subsequent waste processing. While the release of benzene certainly poses both flammability and toxicological safety concerns, the magnitude of the hazard depends on the rate of release. Currently, the mechanisms controlling the benzene release rates are not well understood, and predictive models for estimating benzene release rates are not available. The overall purpose of this study is to obtain quantitative measurements of benzene release rates from a series of ITP slurry stimulants. This information will become a basis for developing a quantitative mechanistic model of benzene release rates. The transient benzene release rate was measured from the surface of various ITP slurry (solution) samples mixed with benzene. The benzene release rate was determined by continuously purging the headspace of a sealed sample vessel with an inert gas (nitrogen) and analyzing that purged headspace vapor for benzene every 3 minutes. The following 75-mL samples were measured for release rates: KTPB slurry with 15,000 ppm freshly added benzene that was gently mixed with the slurry, KTPB slurry homogenized (energetically mixed) with 15,000 ppm and 5,000 ppm benzene, clear and filtered KTPB salt solution saturated with benzene (with and without a pure benzene layer on top of the solution), and a slurry sample from a large demonstration experiment (DEMO slurry) containing-benzene generated in situ

  11. Evaluation of ensemble precipitation forecasts generated through post-processing in a Canadian catchment

    Directory of Open Access Journals (Sweden)

    S. K. Jha

    2018-03-01

    Full Text Available Flooding in Canada is often caused by heavy rainfall during the snowmelt period. Hydrologic forecast centers rely on precipitation forecasts obtained from numerical weather prediction (NWP models to enforce hydrological models for streamflow forecasting. The uncertainties in raw quantitative precipitation forecasts (QPFs are enhanced by physiography and orography effects over a diverse landscape, particularly in the western catchments of Canada. A Bayesian post-processing approach called rainfall post-processing (RPP, developed in Australia (Robertson et al., 2013; Shrestha et al., 2015, has been applied to assess its forecast performance in a Canadian catchment. Raw QPFs obtained from two sources, Global Ensemble Forecasting System (GEFS Reforecast 2 project, from the National Centers for Environmental Prediction, and Global Deterministic Forecast System (GDPS, from Environment and Climate Change Canada, are used in this study. The study period from January 2013 to December 2015 covered a major flood event in Calgary, Alberta, Canada. Post-processed results show that the RPP is able to remove the bias and reduce the errors of both GEFS and GDPS forecasts. Ensembles generated from the RPP reliably quantify the forecast uncertainty.

  12. Evaluation of ensemble precipitation forecasts generated through post-processing in a Canadian catchment

    Science.gov (United States)

    Jha, Sanjeev K.; Shrestha, Durga L.; Stadnyk, Tricia A.; Coulibaly, Paulin

    2018-03-01

    Flooding in Canada is often caused by heavy rainfall during the snowmelt period. Hydrologic forecast centers rely on precipitation forecasts obtained from numerical weather prediction (NWP) models to enforce hydrological models for streamflow forecasting. The uncertainties in raw quantitative precipitation forecasts (QPFs) are enhanced by physiography and orography effects over a diverse landscape, particularly in the western catchments of Canada. A Bayesian post-processing approach called rainfall post-processing (RPP), developed in Australia (Robertson et al., 2013; Shrestha et al., 2015), has been applied to assess its forecast performance in a Canadian catchment. Raw QPFs obtained from two sources, Global Ensemble Forecasting System (GEFS) Reforecast 2 project, from the National Centers for Environmental Prediction, and Global Deterministic Forecast System (GDPS), from Environment and Climate Change Canada, are used in this study. The study period from January 2013 to December 2015 covered a major flood event in Calgary, Alberta, Canada. Post-processed results show that the RPP is able to remove the bias and reduce the errors of both GEFS and GDPS forecasts. Ensembles generated from the RPP reliably quantify the forecast uncertainty.

  13. Interactions in the Geo-Biosphere: Processes of Carbonate Precipitation in Microbial Mats

    Science.gov (United States)

    Dupraz, C.; Visscher, P. T.

    2009-12-01

    Microbial communities are situated at the interface between the biosphere, the lithosphere and the hydrosphere. These microbes are key players in the global carbon cycle, where they influence the balance between the organic and inorganic carbon reservoirs. Microbial populations can be organized in microbial mats, which can be defined as organosedimentary biofilms that are dominated by cyanobacteria, and exhibit tight coupling of element cycles. Complex interactions between mat microbes and their surrounding environment can result in the precipitation of carbonate minerals. This process refers as ‘organomineralization sensu lato' (Dupraz et al. in press), which differs from ‘biomineralization’ (e.g., in shells and bones) by lacking genetic control on the mineral product. Organomineralization can be: (1) active, when microbial metabolic reactions are responsible for the precipitation (“biologically-induced” mineralization) or (2) passive, when mineralization within a microbial organic matrix is environmentally driven (e.g., through degassing or desiccation) (“biologically-influenced” mineralization). Studying microbe-mineral interactions is essential to many emerging fields of the biogeoscience, such as the study of life in extreme environments (e.g, deep biosphere), the origin of life, the search for traces of extraterrestrial life or the seek of new carbon sink. This research approach combines sedimentology, biogeochemistry and microbiology. Two tightly coupled components that control carbonate organomineralization s.l.: (1) the alkalinity engine and (2) the extracellular organic matter (EOM), which is ultimately the location of mineral nucleation. Carbonate alkalinity can be altered both by microbial metabolism and environmental factors. In microbial mats, the net accumulation of carbonate minerals often reflect the balance between metabolic activities that consume/produce CO2 and/or organic acids. For example, photosynthesis and sulfate reduction

  14. Monte Carlo simulation study of a selforganisation process leading to ordered precipitate structures

    International Nuclear Information System (INIS)

    Zirkelbach, F.; Haeberlen, M.; Lindner, J.K.N.; Stritzker, B.

    2007-01-01

    Periodically arranged, selforganised, nanometric, amorphous precipitates have been observed after high-fluence ion implantations into solids for a number of ion/target combinations at certain implantation conditions. A model describing the ordering process based on compressive stress exerted by the amorphous inclusions as a result of the density change upon amorphisation is introduced. A Monte Carlo simulation code, which focuses on high-fluence carbon implantations into silicon, is able to reproduce experimentally observed nanolamella distributions as well as the formation of continuous amorphous layers. By means of simulation, the selforganisation process becomes traceable and detailed information about the compositional and structural state during the ordering process is obtained. Based on simulation results, a recipe is proposed for producing broad distributions of ordered lamellar structures

  15. Morphology and Precipitation Kinetics of MnS in Low-Carbon Steel During Thin Slab Continuous Casting Process

    Institute of Scientific and Technical Information of China (English)

    YU Hao; KANG Yong-lin; ZHAO Zheng-zhi; SUN Hao

    2006-01-01

    The morphology of manganese sulfide formed during thin slab continuous casting process in low-carbon steel produced by compact strip production (CSP) technique was investigated. Using transmission electron microscopy analysis, it was seen that a majority of manganese sulfides precipitated at austenite grain boundaries, the morphologies of which were spherical or close to the spherical shape and the size of MnS precipitates ranged from 30 nm to 100 nm. A mathematical model of the manganese sulfide precipitation in this process was developed based on classical nucleation theory. Under the given conditions, the starting and finishing precipitation temperatures of MnS in the continuous casting thin slab of the studied low-carbon steel are 1 189 ℃ and 1 171 ℃, respectively, and the average diameter of MnS precipitates is about 48 nm within this precipitation temperature range. The influences of chemical components and thermo-mechanical processing conditions on the precipitation behavior of MnS in the same process were also discussed.

  16. Quantitative examination of carbide and sulphide precipitates in chemically complex steels processed by direct strip casting

    Energy Technology Data Exchange (ETDEWEB)

    Dorin, Thomas, E-mail: thomas.dorin@deakin.edu.au [Deakin University, Pigdons Road, Geelong, Victoria, 3216 (Australia); Wood, Kathleen [Australian Nuclear Science and Technology Organisation, Bragg Institute, New South Wales, 2234, Menai (Australia); Taylor, Adam; Hodgson, Peter; Stanford, Nicole [Deakin University, Pigdons Road, Geelong, Victoria, 3216 (Australia)

    2016-02-15

    A high strength low alloy steel composition has been melted and processed by two different routes: simulated direct strip casting and slow cooled ingot casting. The microstructures were examined with scanning and transmission electron microscopy, atom probe tomography and small angle neutron scattering (SANS). The formation of cementite (Fe{sub 3}C), manganese sulphides (MnS) and niobium carbo-nitrides (Nb(C,N)) was investigated in both casting conditions. The sulphides were found to be significantly refined by the higher cooling rate, and developed an average diameter of only 100 nm for the fast cooled sample, and a diameter too large to be measured with SANS in the slow cooled condition (> 1.1 μm). Slow cooling resulted in the development of classical Nb(C,N) precipitation, with an average diameter of 7.2 nm. However, after rapid cooling both the SANS and atom probe tomography data indicated that the Nb was retained in the matrix as a random solid solution. There was also some evidence that O, N and S are also retained in solid solution in levels not found during conventional processing. - Highlights: • The influence of cooling rate on microstructure is investigated in a HSLA steel. • SANS, TEM and APT are used to characterise the sulphides and Nb(C,N) precipitates. • The slow cooling rate result in the formation of Nb(C,N) precipitates. • The fast cooling rate results in a microstructure supersaturated in Nb, C and N. • The sulphides are 100 nm in the fast cooled sample and > 1 μm in the slow cooled one.

  17. Precipitation Sensitivity to the Mean Radius of Drop Spectra: Comparison of Single- and Double-Moment Bulk Microphysical Schemes

    Directory of Open Access Journals (Sweden)

    Nemanja Kovačević

    2015-04-01

    Full Text Available In this study, two bulk microphysical schemes were compared across mean radius values of the entire drop spectra. A cloud-resolving mesoscale model was used to analyze surface precipitation characteristics. The model included the following microphysical categories: water vapour, cloud droplets, raindrops, ice crystals, snow, graupel, frozen raindrops and hail. Two bulk schemes were used: a single-moment scheme in which the mean radius was specified as a parameter and a double-moment scheme in which the mean radius of drops was calculated diagnostically with a fixed value for the cloud droplet number concentration. Experiments were conducted out for three values of the mean radius (in the single-moment scheme and two cloud droplet number concentrations (in the double-moment scheme. There were large differences in the surface precipitation for the two schemes, the simulated precipitation generated by the double-moment scheme had a higher sensitivity. The single-moment scheme generated an unrealistic collection rate of cloud droplets by raindrops and hail as well as unrealistic evaporation of rain and melting of solid hydrometeors; these processes led to inaccurate timing and amounts of surface precipitation.

  18. The Precipitation Processes and Mechanical Properties of Aged Inconel 718 Alloy After Annealing

    Directory of Open Access Journals (Sweden)

    Maj P.

    2017-09-01

    Full Text Available Inconel 718 is a precipitation hardenable nickel-iron based superalloy. It has exceptionally high strength and ductility compared to other metallic materials. This is due to intense precipitation of the γ’ and γ” strengthening phases in the temperature range 650-850°C. The main purpose of the authors was to analyze the aging process in Inconel 718 obtained in accordance with AMS 5596, and its effect on the mechanical properties. Tensile and hardness tests were used to evaluate the mechanical properties, in the initial aging process and after reheating, as a function of temperature and time respectively in the ranges 650°-900°C and 5-480 min. In addition, to link the mechanical properties with the microstructure transmission microscopy observations were carried out in selected specimens. As a result, factors influencing the microstructure changes at various stages of strengthening were observed. The authors found that the γ’’ phase nucleates mostly homogenously in the temperature range 650-750°C, causing the greatest increase in strength. On the other hand, the γ’ and δ phases are formed heterogeneously at 850°C or after longer annealing in 800°C, which may weaken the material.

  19. Effect of Temperature on Precipitation Rate of Calcium Carbonate Produced through Microbial Metabolic Process of Bio Materials

    Directory of Open Access Journals (Sweden)

    Prima Yane Putri

    2016-09-01

    Full Text Available Concrete is the most widely used construction material in civil engineering. But plain concrete is a brittle material and has little resistance to cracking. The cracking in concrete promotes deterioration such as the corrosion of reinforcing rebar, therefore, repair in filling the crack is often carried out. Recently, repair methods using bio-based materials associated with microbial metabolic processes leading to precipitation of calcium carbonate have been intensively studied. In this study, influencing factors on the precipitation rate depending on the constituents of bio-based material comprising yeast, glucose and calcium acetate mixed in tris buffer solution was examined for improving the rate of initial reactions. In addition, effect of temperature change on the amount of calcium carbonate precipitation was also investigated. The precipitates were identified by X-ray diffraction. It was shown that the increase of temperature lead to a change on calcium carbonate precipitation and caused the pH decrease under 7.0.

  20. Quality-by-Design (QbD): An integrated process analytical technology (PAT) approach for a dynamic pharmaceutical co-precipitation process characterization and process design space development.

    Science.gov (United States)

    Wu, Huiquan; White, Maury; Khan, Mansoor A

    2011-02-28

    The aim of this work was to develop an integrated process analytical technology (PAT) approach for a dynamic pharmaceutical co-precipitation process characterization and design space development. A dynamic co-precipitation process by gradually introducing water to the ternary system of naproxen-Eudragit L100-alcohol was monitored at real-time in situ via Lasentec FBRM and PVM. 3D map of count-time-chord length revealed three distinguishable process stages: incubation, transition, and steady-state. The effects of high risk process variables (slurry temperature, stirring rate, and water addition rate) on both derived co-precipitation process rates and final chord-length-distribution were evaluated systematically using a 3(3) full factorial design. Critical process variables were identified via ANOVA for both transition and steady state. General linear models (GLM) were then used for parameter estimation for each critical variable. Clear trends about effects of each critical variable during transition and steady state were found by GLM and were interpreted using fundamental process principles and Nyvlt's transfer model. Neural network models were able to link process variables with response variables at transition and steady state with R(2) of 0.88-0.98. PVM images evidenced nucleation and crystal growth. Contour plots illustrated design space via critical process variables' ranges. It demonstrated the utility of integrated PAT approach for QbD development. Published by Elsevier B.V.

  1. Intercomparison of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds

    Science.gov (United States)

    Muhlbauer, A.; Hashino, T.; Xue, L.; Teller, A.; Lohmann, U.; Rasmussen, R. M.; Geresdi, I.; Pan, Z.

    2010-09-01

    Anthropogenic aerosols serve as a source of both cloud condensation nuclei (CCN) and ice nuclei (IN) and affect microphysical properties of clouds. Increasing aerosol number concentrations is hypothesized to retard the cloud droplet coalescence and the riming in mixed-phase clouds, thereby decreasing orographic precipitation. This study presents results from a model intercomparison of 2-D simulations of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds. The sensitivity of orographic precipitation to changes in the aerosol number concentrations is analysed and compared for various dynamical and thermodynamical situations. Furthermore, the sensitivities of microphysical processes such as coalescence, aggregation, riming and diffusional growth to changes in the aerosol number concentrations are evaluated and compared. The participating numerical models are the model from the Consortium for Small-Scale Modeling (COSMO) with bulk microphysics, the Weather Research and Forecasting (WRF) model with bin microphysics and the University of Wisconsin modeling system (UWNMS) with a spectral ice habit prediction microphysics scheme. All models are operated on a cloud-resolving scale with 2 km horizontal grid spacing. The results of the model intercomparison suggest that the sensitivity of orographic precipitation to aerosol modifications varies greatly from case to case and from model to model. Neither a precipitation decrease nor a precipitation increase is found robustly in all simulations. Qualitative robust results can only be found for a subset of the simulations but even then quantitative agreement is scarce. Estimates of the aerosol effect on orographic precipitation are found to range from -19% to 0% depending on the simulated case and the model. Similarly, riming is shown to decrease in some cases and models whereas it increases in others, which implies that a decrease in riming with increasing aerosol load is not a robust result

  2. The influence of green microstructure and sintering parameters on precipitation process during copper-nickel-zinc ferrites sintering

    International Nuclear Information System (INIS)

    Barba, A.; Clausell, C.; Jarque, J. C.; Monzo, M.

    2014-01-01

    Microstructural changes that occur during heat treatment of copper-nickel-zinc ferrites have been studied. The process of precipitation of the two types of crystals that occur during the sintering process has been analyzed. It is found that this process depends on dry relative density of the press specimens and on the following sintering parameters: sintering temperature, sintering time and cooling rate of the thermal cycle. Crystal precipitates characterization have been done by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These techniques have allowed to determine the nature of these crystals, which in this case correspond to zinc and copper oxides. It has been used two chemical reactions to explain the bulk precipitation and subsequent re-dissolution of these crystal precipitates during sintering. (Author)

  3. Development and Demonstration of a Sulfate Precipitation Process for Hanford Waste Tank 241-AN-107

    International Nuclear Information System (INIS)

    Fiskum, S.K.; Kurath, D.E.; Rapko, B.M.

    2000-01-01

    A series of precipitation experiments were conducted on Hanford waste tank 241-AN-107 samples in an effort to remove sulfate from the matrix. Calcium nitrate was added directly to AN-107 sub-samples to yield several combinations of Ca:CO 3 mole ratios spanning a range of 0:1 to 3:1 to remove carbonate as insoluble CaCO 3 . Similarly barium nitrate was added directly to the AN-107 aliquots, or to the calcium pretreated AN-107 aliquots, giving of Ba:SO 4 mole ratios spanning a range of 1:1 to 5:1 to precipitate sulfate as BaSO 4 . Initial bulk carbonate removal was required for successful follow-on barium sulfate precipitation. A ge 1:1 mole ratio of Ca:CO 3 was found to lower the carbonate concentration such that Ba would react preferentially with the sulfate. A follow-on 1:1 mole ratio of Ba:SO 4 resulted in 70% sulfate removal. The experiment was scaled up with a 735-mL aliquot of AN-107 for more complete testing. Calcium carbonate and barium sulfate settling rates were determined and fates of selected cations, anions, and radionuclides were followed through the various process steps. Seventy percent of the sulfate was removed in the scale-up test while recovering 63% of the filtrate volume. Surprisingly, during the scale-up test a sub-sample of the CaCO 3 /241-AN-107 slurry was found to lose fluidity upon standing for le 2 days. Metathesis with BaCO 3 at ambient temperature was also evaluated using batch contacts at various BaCO 3 :SO 4 mole ratios with no measurable success

  4. Development and Demonstration of a Sulfate Precipitation Process for Hanford Waste Tank 241-AN-107

    Energy Technology Data Exchange (ETDEWEB)

    SK Fiskum; DE Kurath; BM Rapko

    2000-08-16

    A series of precipitation experiments were conducted on Hanford waste tank 241-AN-107 samples in an effort to remove sulfate from the matrix. Calcium nitrate was added directly to AN-107 sub-samples to yield several combinations of Ca:CO{sub 3} mole ratios spanning a range of 0:1 to 3:1 to remove carbonate as insoluble CaCO{sub 3}. Similarly barium nitrate was added directly to the AN-107 aliquots, or to the calcium pretreated AN-107 aliquots, giving of Ba:SO{sub 4} mole ratios spanning a range of 1:1 to 5:1 to precipitate sulfate as BaSO{sub 4}. Initial bulk carbonate removal was required for successful follow-on barium sulfate precipitation. A {ge} 1:1 mole ratio of Ca:CO{sub 3} was found to lower the carbonate concentration such that Ba would react preferentially with the sulfate. A follow-on 1:1 mole ratio of Ba:SO{sub 4} resulted in 70% sulfate removal. The experiment was scaled up with a 735-mL aliquot of AN-107 for more complete testing. Calcium carbonate and barium sulfate settling rates were determined and fates of selected cations, anions, and radionuclides were followed through the various process steps. Seventy percent of the sulfate was removed in the scale-up test while recovering 63% of the filtrate volume. Surprisingly, during the scale-up test a sub-sample of the CaCO{sub 3}/241-AN-107 slurry was found to lose fluidity upon standing for {le} 2 days. Metathesis with BaCO{sub 3} at ambient temperature was also evaluated using batch contacts at various BaCO{sub 3}:SO{sub 4} mole ratios with no measurable success.

  5. Evaluation of the significance of abrupt changes in precipitation and runoff process in China

    Science.gov (United States)

    Xie, Ping; Wu, Ziyi; Sang, Yan-Fang; Gu, Haiting; Zhao, Yuxi; Singh, Vijay P.

    2018-05-01

    Abrupt changes are an important manifestation of hydrological variability. How to accurately detect the abrupt changes in hydrological time series and evaluate their significance is an important issue, but methods for dealing with them effectively are lacking. In this study, we propose an approach to evaluate the significance of abrupt changes in time series at five levels: no, weak, moderate, strong, and dramatic. The approach was based on an index of correlation coefficient calculated for the original time series and its abrupt change component. A bigger value of correlation coefficient reflects a higher significance level of abrupt change. Results of Monte-Carlo experiments verified the reliability of the proposed approach, and also indicated the great influence of statistical characteristics of time series on the significance level of abrupt change. The approach was derived from the relationship between correlation coefficient index and abrupt change, and can estimate and grade the significance levels of abrupt changes in hydrological time series. Application of the proposed approach to ten major watersheds in China showed that abrupt changes mainly occurred in five watersheds in northern China, which have arid or semi-arid climate and severe shortages of water resources. Runoff processes in northern China were more sensitive to precipitation change than those in southern China. Although annual precipitation and surface water resources amount (SWRA) exhibited a harmonious relationship in most watersheds, abrupt changes in the latter were more significant. Compared with abrupt changes in annual precipitation, human activities contributed much more to the abrupt changes in the corresponding SWRA, except for the Northwest Inland River watershed.

  6. Precipitation modeling of inclusions at different stages of the steel making process

    International Nuclear Information System (INIS)

    Carreno, V.; Morales, R.D.; Romeero, A.; Hernandez, M.; Morales, R.D.

    1998-01-01

    Steel making processes are continuously improved in order to attend the increasing requirements of the cleanness of the liquid metal. At the refining stages, as deoxidation and desulphuration, the formation of inclusions of oxides and sulphides is promoted, which on the other hand, are the most frequent inclusions. In this work a mathematical simulator of the precipitation and chemical composition of non-metallic inclusions at different steps of the steel making process is presented. To this purpose, it is assumed that inclusions formed by reoxidation can be simulated by increasing arbitrarily the oxygen levels consumed by the residual elements (aluminium, calcium, etc) and starting the chemical reaction with less powerful deoxidants (silicium and manganese). Accordingly, different operative conditions can be simulated. Numerical predictions are compared with experimental results of industrial trials, as well as results included in the bibliography. (Author) 7 refs

  7. Nanonization of curcumin by antisolvent precipitation: process development, characterization, freeze drying and stability performance.

    Science.gov (United States)

    Yadav, Deepak; Kumar, Neeraj

    2014-12-30

    The present work aims to investigate applicability of antisolvent precipitation method for preparation of nanosized curcumin and to control their characteristics by determining the influence of process and solvents on solid-state properties of curcumin nanoparticles. Effects of different experimental parameters on particle size were investigated using dynamic light scattering. Particle morphology was studied using SEM. Drug content in stabilized nanoparticles was determined using HPLC. Residual moisture content after lyophilisation was determined using Karl Fischer method and solid state properties were investigated using DSC, TGA, FTIR and powder-XRD. The resulting product showed a high drug load and contained the drug in amorphous form. The particle diameters of prepared curcumin nanoparticles were found in the range of 100-200 nm. In vitro drug release studies indicated a sustained release profile of curcumin from the nanoparticles. Antisolvent precipitation produced amorphous curcumin nanoparticles whose size and morphology could be controlled using gelatine as stabilizer. Lyophilized curcumin nanoparticles with d-sorbitol as lyoprotectant possessed good redispersibility and showed up to 4 times faster in vitro curcumin release rate than that of unprocessed curcumin. Stability tests (at 2-8°C and ambient conditions) indicated that the product was stable for up to 6 months of storage. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Processing of next generation weather radar-multisensor precipitation estimates and quantitative precipitation forecast data for the DuPage County streamflow simulation system

    Science.gov (United States)

    Bera, Maitreyee; Ortel, Terry W.

    2018-01-12

    The U.S. Geological Survey, in cooperation with DuPage County Stormwater Management Department, is testing a near real-time streamflow simulation system that assists in the management and operation of reservoirs and other flood-control structures in the Salt Creek and West Branch DuPage River drainage basins in DuPage County, Illinois. As part of this effort, the U.S. Geological Survey maintains a database of hourly meteorological and hydrologic data for use in this near real-time streamflow simulation system. Among these data are next generation weather radar-multisensor precipitation estimates and quantitative precipitation forecast data, which are retrieved from the North Central River Forecasting Center of the National Weather Service. The DuPage County streamflow simulation system uses these quantitative precipitation forecast data to create streamflow predictions for the two simulated drainage basins. This report discusses in detail how these data are processed for inclusion in the Watershed Data Management files used in the streamflow simulation system for the Salt Creek and West Branch DuPage River drainage basins.

  9. The precipitation process in Mg-Ca-(Zn) alloys investigated by positron annihilation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Yanicet [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Departamento de Fisica de Materiales, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)], E-mail: yanicet@fis.ucm.es; Monge, Miguel Angel; Pareja, Ramiro [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2008-09-08

    Coincidence doppler broadening (CDB) spectroscopy has been applied to study the precipitation process induced by aging in Mg-1.0 wt.% Ca and Mg-1.0 wt.% Ca-1.0 wt.% Zn alloys. In addition positron lifetime experiments and microhardness measurements have been performed. A peak centered at {approx}11.5 x 10{sup -3}m{sub 0}c is found in the CDB ratio spectra of the alloys aged at 473 K. It is attributed to annihilations with the core electrons of Ca. The results indicate the formation of a particle dispersion that hardens the alloys. This dispersion is correlated with the appearance of the peak attributed to Ca atoms. Zn atoms in the Mg matrix inhibit the formation of quenched-in vacancies bound to Ca atoms in the aged ternary alloy producing the dispersion refinement.

  10. The precipitation process in Mg-Ca-(Zn) alloys investigated by positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    Ortega, Yanicet; Monge, Miguel Angel; Pareja, Ramiro

    2008-01-01

    Coincidence doppler broadening (CDB) spectroscopy has been applied to study the precipitation process induced by aging in Mg-1.0 wt.% Ca and Mg-1.0 wt.% Ca-1.0 wt.% Zn alloys. In addition positron lifetime experiments and microhardness measurements have been performed. A peak centered at ∼11.5 x 10 -3 m 0 c is found in the CDB ratio spectra of the alloys aged at 473 K. It is attributed to annihilations with the core electrons of Ca. The results indicate the formation of a particle dispersion that hardens the alloys. This dispersion is correlated with the appearance of the peak attributed to Ca atoms. Zn atoms in the Mg matrix inhibit the formation of quenched-in vacancies bound to Ca atoms in the aged ternary alloy producing the dispersion refinement

  11. Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

    International Nuclear Information System (INIS)

    Shih, C.J.; Chen, Y.J.; Hon, M.H.

    2010-01-01

    Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol -1 .

  12. Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Shih, C.J., E-mail: cjshih@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Chen, Y.J. [Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hon, M.H. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2010-05-15

    Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol{sup -1}.

  13. The mechanism underlying calcium phosphate precipitation on titanium via ultraviolet, visible, and near infrared laser-assisted biomimetic process

    International Nuclear Information System (INIS)

    Mahanti, Moumita; Nakamura, Maki; Pyatenko, Alexander; Sakamaki, Ikuko; Koga, Kenji; Oyane, Ayako

    2016-01-01

    We recently developed a rapid single-step calcium phosphate (CaP) precipitation technique on several substrates using a laser-assisted biomimetic process (LAB process). In this process, ultraviolet (UV, λ   =  355 nm) pulsed laser irradiation has been applied to a substrate that is immersed in a supersaturated CaP solution. In the present study, the LAB process for CaP precipitation on a titanium substrate was successfully expanded to include not only UV but also visible (VIS, λ   =  532 nm) and near infrared (NIR, λ   =  1064 nm) lasers. Surface heating and plasma-mediated surface reactions (micro-deformation, oxidization, photoexcitation, and wetting) generated by UV, VIS, or NIR lasers are considered to be involved in the CaP precipitation on the titanium surface in the LAB process. The kinetics of these reactions and consequently of CaP precipitation were dependent on the laser wavelength and fluence. The higher laser fluence did not always accelerate CaP precipitation on the substrate; rather, it was found that an optimal range of fluence exists for each laser wavelength. These results suggest that for efficient CaP precipitation, a suitable laser wavelength should be selected according to the optical absorption properties of the substrate material and the laser fluence should also be adjusted to induce surface heating and plasma-mediated surface reactions that are favorable for CaP precipitation. (paper)

  14. Design of a continuous process setup for precipitated calcium carbonate production from steel converter slag.

    Science.gov (United States)

    Mattila, Hannu-Petteri; Zevenhoven, Ron

    2014-03-01

    A mineral carbonation process "slag2PCC" for carbon capture, utilization, and storage is discussed. Ca is extracted from steel slag by an ammonium salt solvent and carbonated with gaseous CO2 after the separation of the residual slag. The solvent is reused after regeneration. The effects of slag properties such as the content of free lime, fractions of Ca, Si, Fe, and V, particle size, and slag storage on the Ca extraction efficiency are studied. Small particles with a high free-lime content and minor fractions of Si and V are the most suitable. To limit the amount of impurities in the process, the slag-to-liquid ratio should remain below a certain value, which depends on the slag composition. Also, the design of a continuous test setup (total volume ∼75 L) is described, which enables quick process variations needed to adapt the system to the varying slag quality. Different precipitated calcium carbonate crystals (calcite and vaterite) are generated in different parts of the setup. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Stability investigations of zinc and cobalt precipitates immobilized by in situ bioprecipitation (ISBP) process

    KAUST Repository

    Satyawali, Yamini; Schols, Edo; Van Roy, Sandra; Dejonghe, Winnie; Diels, Ludo; Vanbroekhoven, Karolien

    2010-01-01

    In situ bioprecipitation (ISBP), which involves immobilizing the metals as precipitates (mainly sulphides) in the solid phase, is an effective method of metal removal from contaminated groundwater. This study investigated the stability of metal precipitates formed after ISBP in two different solid-liquid matrices (artificial and natural). The artificial matrix consisted of sand, Zn (200mgL-1), artificial groundwater and a carbon source (electron donor). Here the stability of the Zn precipitates was evaluated by manipulation of redox and pH. The natural system matrices included aquifer material and groundwater samples collected from three different metal (Zn and Co) contaminated sites and different carbon sources were provided as electron donors. In the natural matrices, metal precipitates stability was assessed by changing aquifer redox conditions, sequential extraction, and BIOMET® assay. The results indicated that, in the artificial matrix, redox manipulation did not impact the Zn precipitates. However the sequential pH change proved detrimental, releasing 58% of the precipitated Zn back into liquid phase. In natural matrices, the applied carbon source largely affected the stability of metal precipitates. Elemental analysis performed on the precipitates formed in natural matrix showed that the main elements of the precipitates were sulphur with Zn and Co. © 2010 Elsevier B.V.

  16. Stability investigations of zinc and cobalt precipitates immobilized by in situ bioprecipitation (ISBP) process

    KAUST Repository

    Satyawali, Yamini

    2010-09-01

    In situ bioprecipitation (ISBP), which involves immobilizing the metals as precipitates (mainly sulphides) in the solid phase, is an effective method of metal removal from contaminated groundwater. This study investigated the stability of metal precipitates formed after ISBP in two different solid-liquid matrices (artificial and natural). The artificial matrix consisted of sand, Zn (200mgL-1), artificial groundwater and a carbon source (electron donor). Here the stability of the Zn precipitates was evaluated by manipulation of redox and pH. The natural system matrices included aquifer material and groundwater samples collected from three different metal (Zn and Co) contaminated sites and different carbon sources were provided as electron donors. In the natural matrices, metal precipitates stability was assessed by changing aquifer redox conditions, sequential extraction, and BIOMET® assay. The results indicated that, in the artificial matrix, redox manipulation did not impact the Zn precipitates. However the sequential pH change proved detrimental, releasing 58% of the precipitated Zn back into liquid phase. In natural matrices, the applied carbon source largely affected the stability of metal precipitates. Elemental analysis performed on the precipitates formed in natural matrix showed that the main elements of the precipitates were sulphur with Zn and Co. © 2010 Elsevier B.V.

  17. STRONTIUM PRECIPITATION

    Science.gov (United States)

    McKenzie, T.R.

    1960-09-13

    A process is given for improving the precipitation of strontium from an aqueous phosphoric-acid-containing solution with nickel or cobalt ferrocyanide by simultaneously precipitating strontium or calcium phosphate. This is accomplished by adding to the ferrocyanide-containing solution calcium or strontium nitrate in a quantity to yield a concentration of from 0.004 to 0.03 and adjusting the pH of the solution to a value of above 8.

  18. Precipitation process for the removal of technetium values from nuclear waste solutions

    Science.gov (United States)

    Walker, D.D.; Ebra, M.A.

    1985-11-21

    High efficiency removal of techetium values from a nuclear waste stream is achieved by addition to the waste stream of a precipitant contributing tetraphenylphosphonium cation, such that a substantial portion of the technetium values are precipitated as an insoluble pertechnetate salt.

  19. Processing, Microstructures and Properties of a Dual Phase Precipitation-Hardening PM Stainless Steel

    Science.gov (United States)

    Schade, Christopher

    To improve the mechanical properties of PM stainless steels in comparison with their wrought counterparts, a PM stainless steel alloy was developed which combines a dual-phase microstructure with precipitation-hardening. The use of a mixed microstructure of martensite and ferrite results in an alloy with a combination of the optimum properties of each phase, namely strength and ductility. The use of precipitation hardening via the addition of copper results in additional strength and hardness. A range of compositions was studied in combination with various sintering conditions to determine the optimal thermal processing to achieve the desired microstructure. The microstructure could be varied from predominately ferrite to one containing a high percentage of martensite by additions of copper and a variation of the sintering temperature before rapid cooling. Mechanical properties (transverse rupture strength (TRS), yield strength, tensile strength, ductility and impact toughness) were measured as a function of the v/o ferrite in the microstructure. A dual phase alloy with the optimal combination of properties served as the base for introducing precipitation hardening. Copper was added to the base alloy at various levels and its effect on the microstructure and mechanical properties was quantified. Processing at various sintering temperatures led to a range of microstructures; dilatometry was used utilized to monitor and understand the transformations and the formation of the two phases. The aging process was studied as a function of temperature and time by measuring TRS, yield strength, tensile strength, ductility, impact toughness and apparent hardness. It was determined that optimum aging was achieved at 538°C for 1h. Aging at slightly lower temperatures led to the formation of carbides, which contributed to reduced hardness and tensile strength. As expected, at the peak aging temperature, an increase in yield strength and ultimate tensile strength as well as

  20. Research on a pellet co-precipitation micro-filtration process for the treatment of liquid waste containing strontium

    International Nuclear Information System (INIS)

    Xin Luo; North China Institute of Science and Technology, Beijing; Guanghui Zhang; Xue Wang; Ping Gu

    2013-01-01

    The chemical precipitation method for radioactive wastewater treatment has the advantages of being simple and cost-effective. However, difficulties with the solid–liquid separation and sludge concentration restrict the application of this method. In this paper, a pellet co-precipitation micro-filtration (PCM) process was studied for treating strontium-containing wastewater on a laboratory scale. The seed was prepared by CaCO 3 powders. Sr 2+ and CO 3 2- were constantly crystallised on the seed surface, with Na 2 CO 3 as the precipitating agent in the pellet reactor. The following membrane separator with the addition of FeCl 3 enhanced the treatment effect. The average strontium concentrations in the raw water and in the effluent were 12.0 and 0.0220 mg/L, respectively. The strontium decontamination factor (DF) increased with the operation time, with an average value of 577. The precipitate particles formed gradually grew larger, with good sedimentation properties. When the experiment was complete, the formed precipitate was separated easily from the liquid phase and directly discharged. The concentration factor (CF) was 1,958. In the PCM process, crystallisation was the main mechanism for strontium removal, with the influent strontium level playing an important role. Membrane pore blockage and cake layer formation could help to further intercept the strontium crystallites. Furthermore, ferric chloride coagulation in the membrane separator also contributed to strontium removal. The PCM process has potential for wider application in the removal of strontium from wastewater. (author)

  1. Cintichem modified process - {sup 99}Mo precipitation step: application of statistical analysis tools over the reaction parameters

    Energy Technology Data Exchange (ETDEWEB)

    Teodoro, Rodrigo; Dias, Carla R.B.R.; Osso Junior, Joao A., E-mail: jaosso@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Fernandez Nunez, Eutimio Gustavo [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Quimica

    2011-07-01

    Precipitation of {sup 99}Mo by {alpha}-benzoin oxime ({alpha}-Bz) is a standard precipitation method for molybdenum due the high selectivity of this agent. Nowadays, statistical analysis tools have been employed in analytical systems to prove its efficiency and feasibility. IPEN has a project aiming the production of {sup 99}Mo by the fission of {sup 235}U route. The processing uses as the first step the precipitation of {sup 99}Mo with {alpha}-Bz. This precipitation step involves many key reaction parameters. The aim of this work is based on the development of the already known acidic route to produce {sup 99}Mo as well as the optimization of the reactional parameters applying statistical tools. In order to simulate {sup 99}Mo precipitation, the study was conducted in acidic media using HNO{sub 3}, {alpha}Bz as precipitant agent and NaOH /1%H{sub 2}O{sub 2} as dissolver solution. Then, a Mo carrier, KMnO{sub 4} solutions and {sup 99}Mo tracer were added to the reaction flask. The reactional parameters ({alpha}-Bz/Mo ratio, Mo carrier, reaction time and temperature, and cooling reaction time before filtration) were evaluated under a fractional factorial design of resolution V. The best values of each reactional parameter were determined by a response surface statistical planning. The precipitation and recovery yields of {sup 99}Mo were measured using HPGe detector. Statistical analysis from experimental data suggested that the reactional parameters {alpha}-Bz/Mo ratio, reaction time and temperature have a significant impact on {sup 99}Mo precipitation. Optimization statistical planning showed that higher {alpha}Bz/Mo ratios, room temperature, and lower reaction time lead to higher {sup 99}Mo yields. (author)

  2. Influence of formulation and processing variables on properties of itraconazole nanoparticles made by advanced evaporative precipitation into aqueous solution.

    Science.gov (United States)

    Bosselmann, Stephanie; Nagao, Masao; Chow, Keat T; Williams, Robert O

    2012-09-01

    Nanoparticles, of the poorly water-soluble drug, itraconazole (ITZ), were produced by the Advanced Evaporative Precipitation into Aqueous Solution process (Advanced EPAS). This process combines emulsion templating and EPAS processing to provide improved control over the size distribution of precipitated particles. Specifically, oil-in-water emulsions containing the drug and suitable stabilizers are sprayed into a heated aqueous solution to induce precipitation of the drug in form of nanoparticles. The influence of processing parameters (temperature and volume of the heated aqueous solution; type of nozzle) and formulation aspects (stabilizer concentrations; total solid concentrations) on the size of suspended ITZ particles, as determined by laser diffraction, was investigated. Furthermore, freeze-dried ITZ nanoparticles were evaluated regarding their morphology, crystallinity, redispersibility, and dissolution behavior. Results indicate that a robust precipitation process was developed such that size distribution of dispersed nanoparticles was shown to be largely independent across the different processing and formulation parameters. Freeze-drying of colloidal dispersions resulted in micron-sized agglomerates composed of spherical, sub-300-nm particles characterized by reduced crystallinity and high ITZ potencies of up to 94% (w/w). The use of sucrose prevented particle agglomeration and resulted in powders that were readily reconstituted and reached high and sustained supersaturation levels upon dissolution in aqueous media.

  3. Periodic precipitation a microcomputer analysis of transport and reaction processes in diffusion media, with software development

    CERN Document Server

    Henisch, H K

    1991-01-01

    Containing illustrations, worked examples, graphs and tables, this book deals with periodic precipitation (also known as Liesegang Ring formation) in terms of mathematical models and their logical consequences, and is entirely concerned with microcomputer analysis and software development. Three distinctive periodic precipitation mechanisms are included: binary diffusion-reaction; solubility modulation, and competitive particle growth. The book provides didactic illustrations of a valuable investigational procedure, in the form of hypothetical experimentation by microcomputer. The development

  4. A continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs.

    Science.gov (United States)

    Dong, Yuancai; Ng, Wai Kiong; Hu, Jun; Shen, Shoucang; Tan, Reginald B H

    2010-02-15

    Rapid and homogeneous mixing of the solvent and antisolvent is critical to achieve submicron drug particles by antisolvent precipitation technique. This work aims to develop a continuous and highly effective static mixing process for antisolvent precipitation of nanoparticles of poorly water-soluble drugs with spironolactone as a model drug. Continuous antisolvent production of drug nanoparticles was carried out with a SMV DN25 static mixer comprising 6-18 mixing elements. The total flow rate ranged from 1.0 to 3.0 L/min while the flow rate ratio of solvent to antisolvent was maintained at 1:9. It is found that only 6 mixing elements were sufficient to precipitate the particles in the submicron range. Increasing the number of elements would further reduce the precipitated particle size. Increasing flow rate from 1.0 to 3.0 L/min did not further reduce the particle size, while higher drug concentrations led to particle size increase. XRD and SEM results demonstrated that the freshly precipitated drug nanoparticles are in the amorphous state, which would, in presence of the mixture of solvent and antisolvent, change to crystalline form in short time. The lyophilized spironolactone nanoparticles with lactose as lyoprotectant possessed good redispersibility and showed 6.6 and 3.3 times faster dissolution rate than that of lyophilized raw drug formulation in 5 and 10 min, respectively. The developed static mixing process exhibits high potential for continuous and large-scale antisolvent precipitation of submicron drug particles. Copyright 2009 Elsevier B.V. All rights reserved.

  5. In-situ formation of complex oxide precipitates during processing of oxide dispersion strengthened ferritic steels

    International Nuclear Information System (INIS)

    Jayasankar, K.; Pandey, Abhishek; Mishra, B.K.; Das, Siddhartha

    2016-01-01

    Highlights: • Use of dual drive planetary ball mill for Bench scale (>1 kg) production. • X-ray diffraction and TEM were used to study transformations during sintering. • HIPped and rolled samples with nearly 99% density successfully produced. - Abstract: In fusion and fission reactor material development, ODS alloys are the most suitable candidate materials due to its high temperature creep properties and irradiation resistance properties. This paper describes the preparation of oxide dispersion strengthened alloy powder in large quantity (>1 kg batch) in dual drive planetary ball mill using pre-alloyed ferrtic steel powder with nano sized Y_2O_3. The consolidation of the powders was carried out in hot isostatic press (HIP) followed by hot rolling. 99% of the theoretical density was achieved by this method. The vickers hardness values of pressed and rolled samples were in the range of 380 ± 2HV and 719 ± 2HV, respectively. Samples were further investigated using X-ray diffraction particle size analyzer and electron microscope. Initial increase in particle size with milling was observed showing flattening of the particle. It was found that 5 h of milling time is sufficient to reduce the particle size to achieve the desired size. Transmission electron microscopy analysis of milled ODS steel powder revealed a uniform distribution of combustion synthesized nano-Y_2O_3 in ferritic steel matrix after a milling time of 5 h. Preliminary results demonstrated suitability of dual drive planetary ball mill for mass production of alloy within a short time due to various kinds of forces acting at a time during milling process. Fine monoclinic Y_2Si_2O_7 precipitates were also observed in the steel. This study explains the particle characteristics of nano Y_2O_3 dispersed ODS powder and formation of nano clusters in ODS ferritic alloy.

  6. Precipitation behavior and compositional change during the aging process on Type 316 stainless steels

    International Nuclear Information System (INIS)

    Kinoshita, H.; Takahashi, H.; Nagasaki, R.; Ohnuki, S.; Sato, Y.; Mochizuki, S.

    1988-01-01

    The precipitation behavior of two species of the thermally aged SUS316 stainless steels (A and B) were examined. After solution treatment followed by 20 % cold work, the materials were aged at 500∼700deg C for 1000∼18000 hrs. The structures of the aged materials were investigated by means of Transmission Electron Microscope (TEM) and the mean size, the number density and morphology of precipitates were measured. According to these measurements, the mean size increased with the increase in temperature but the number density was only slightly changed above 600deg C. Furthermore the precipitates were identified by using a Energy Dispersive X-ray Spectroscopy (EDS) and electron diffraction technique. From these analysis, the effects of thermal aging conditions on precipitation behavior were discussed, and finally Time-Temperature-Precipitation (TTP) curve was constructed. According to measurements of concentration on Laves phase compared to 600deg C and 700deg C, it was claryfied that the concentration of Mo increased and that of Cr, Ni, Si decreased with the increase in temperature. (author)

  7. Characterization Of Mg(OH)2 Precipitation On MSF Desalination Process

    International Nuclear Information System (INIS)

    Sumijanto

    2000-01-01

    The experiment of Mg(OH) sub.2 precipitation has been carry out. Experiment took please by heating sea water simulation with consist of 142 ppm bicarbonate and magnesium ion at temperature 40, 50, 60, 70, 80, 90, 100, 110, and 120 exp.oC respectively by using autoclave. Sampling has been done periodical for 30 minute in interval 300 minute for each temperature. The calculation of Mg(OH) sub.2 precipitation through the decreasing of magnesium concentration with analysis by AAS. From experiment data have the information that Mg(OH) sub.2 precipitation have been formed since 40 exp.oC. From time variable have been the information that the precipitation formed at 30th minute rapidly. Whether at further time the increasing of precipitation are not significant. This phenomena can explained that at each heating step from 40 exp.oC bicarbonate ion be come decomposition with the result carbonate and hydroxide ion and react with magnesium form Mg(OH) sub.2

  8. Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys

    Directory of Open Access Journals (Sweden)

    Kuchariková L.

    2017-03-01

    Full Text Available The formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h, followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.

  9. Post-precipitations from MOX fuel solutions and analysis of microparticle formation in the PUREX process

    International Nuclear Information System (INIS)

    Henkelmann, R.; Baumgaertner, F.; Klein, F.; Niestroj, B.

    1989-01-01

    Subsequent precipitates of feed solutions from reprocessing were examined with the aid of the SEM-EDX method. On the one hand the examinations give information about the particle form and size distribution, on the other hand about the element distribution in single particles with consideration of the radiation data of the fuel. The subsequent precipitation samples which are examined in this study were taken after different residence times of the clarified fuel solutions. The examinations give information about the kind, element frequency, distribution and stoichiometry of single particles of the submicro- and microrange. (RB) [de

  10. Precipitation process of Z-phase in 9-12%CR steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson

    2014-01-01

    Precipitation of Z-phase, Cr(V,Nb)N, is known to negatively affect creep properties of 9-12%Cr steels for power plant applications as it dissolves finely distributed MX particles, (V,Nb)N, especially in high Cr steels. As the Z-phase precipitates slowly as large particles, this causes a net drop ...... and crystallographically into Z-phase CrTaN particles. Copyright © 2014 Electric Power Research Institute, Inc. Distributed by ASM International®. All rights reserved....

  11. Exploring geophysical processes influencing U.S. West Coast precipitation and water supply

    Science.gov (United States)

    Ralph, F.M.; Prather, K.; Cayan, D.

    2011-01-01

    CalWater Science Workshop; La Jolla, California, 8-10 June 2011 CalWater is a multiyear, multiagency research project with two primary research themes: the effects of changing climate on atmospheric rivers (ARs) and associated extreme events, and the potential role of aerosols in modulating cloud properties and precipitation, especially regarding orographic precipitation and water supply. Advances made in CalWater have implications for both water supply and flood control in California and other West Coast areas, both in the near term and in a changing climate.

  12. Dynamic and thermodynamic processes driving the January 2014 precipitation record in southern UK

    Science.gov (United States)

    Oueslati, B.; Yiou, P.; Jezequel, A.

    2017-12-01

    Regional extreme precipitation are projected to intensify as a response to planetary climate change, with important impacts on societies. Understanding and anticipating those events remain a major challenge. In this study, we revisit the mechanisms of winter precipitation record that occurred in southern United Kingdom in January 2014. The physical drivers of this event are analyzed using the water vapor budget. Precipitation changes are decomposed into dynamic contributions, related to changes in atmospheric circulation, and thermodynamic contributions, related to changes in water vapor. We attempt to quantify the relative importance of the two contributions during this event and examine the applicability of Clausius-Clapeyron scaling. This work provides a physical interpretation of the mechanisms associated with Southern UK's wettest event, which is complementary to other studies based on statistical approaches (Schaller et al., 2016, Yiou et al., 2017). The analysis is carried out using the ERA-Interim reanalysis. This is motivated by the horizontal resolution of this dataset. It is then applied to present-day simulations and future projections of CMIP5 models on selected extreme precipitation events in southern UK that are comparable to January 2014 in terms of atmospheric circulation.References:Schaller, N. et al. Human influence on climate in the 2014 southern England winter floods and their impacts, Nature Clim. Change, 2016, 6, 627-634 Yiou, P., et al. A statistical framework for conditional extreme event attribution Advances in Statistical Climatology, Meteorology and Oceanography, 2017, 3, 17-31

  13. Precipitation Processes during Non-Isothermal Ageing of Fine-Grained 2024 Alloy

    Directory of Open Access Journals (Sweden)

    Kozieł J.

    2016-03-01

    Full Text Available Mechanical alloying and powder metallurgy procedures were used to manufacture very fine-grained bulk material made from chips of the 2024 aluminum alloy. Studies of solution treatment and precipitation hardening of as-received material were based on differential scanning calorimetry (DSC tests and TEM/STEM/EDX structural observations. Structural observations complemented by literature data lead to the conclusion that in the case of highly refined structure of commercial 2024 alloys prepared by severe plastic deformation, typical multi-step G-P-B →θ” →θ’ →θ precipitation mechanism accompanied with G-P-B →S” →S’ →S precipitation sequences result in skipping the formation of metastable phases and direct growth of the stable phases. Exothermic effects on DSC characteristics, which are reported for precipitation sequences in commercial materials, were found to be reduced with increased milling time. Moreover, prolonged milling of 2024 chips was found to shift the exothermic peak to lower temperature with respect to the material produced by means of common metallurgy methods. This effect was concluded to result from preferred heterogeneous nucleation of particles at subboundaries and grain boundaries, enhanced by the boundary diffusion in highly refined structures.

  14. Kinetic study of the precipitation of radioactive elements in the production process of phosphoric acid

    International Nuclear Information System (INIS)

    Ben Mahmoud, Souha

    2009-01-01

    In this engineering study we determined the activities of gamma emitting radionuclides belonging to the families of 238 U , 232 Th and 40K in phosphate, the acid derivatives and gypsum in Tunisian Chemical Group. The most important activities are those of 238 U and 226 Ra, which are located in the phosphate, gypsum and the precipitates formed in the pipes.

  15. Precipitation-adsorption process for the decontamination of nuclear waste supernates

    Science.gov (United States)

    Lee, L.M.; Kilpatrick, L.L.

    1982-05-19

    High-level nuclear waste supernate is decontaminated of cesium by precipitation of the cesium and potassium with sodium tetraphenyl boron. Simultaneously, strontium-90 is removed from the waste supernate sorption of insoluble sodium titanate. The waste solution is then filtered to separate the solution decontaminated of cesium and strontium.

  16. Effects of solvent and alkaline earth metals on the heat-induced precipitation process of sodium caseinate.

    Science.gov (United States)

    Lopez, Francesco; Cuomo, Francesca; Nostro, Pierandrea Lo; Ceglie, Andrea

    2013-01-01

    The precipitation temperatures of sodium caseinate in H(2)O and D(2)O in the presence of Mg(2+), Ca(2+), Sr(2+) and Ba(2+) were investigated through fluorescence, turbidity and conductivity experiments. As for the ability of the divalent cations (1-17.5mM) to induce the precipitation process in H(2)O, the sequence Ba(2+) ≥ Ca(2+)>Mg(2+)>Sr(2+) was found. Remarkably, while at low salt concentrations (10mM) the differences among the different cations were greatly reduced. By fitting these results with a modified Jones-Dole equation, we confirmed that the less hydrated ions possess a greater capacity to induce precipitation. In D(2)O, the order of ion ability to induce caseinate precipitation was Ba(2+)>Ca(2+)>Sr(2+)>Mg(2+). The different hydrophobicity between D(2)O and H(2)O was shown to affect significantly the T(Ps) of caseinate in the presence of calcium, strontium and barium. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Elementary martensitic transformation processes in Ni-rich NiTi single crystals with Ni4Ti3 precipitates

    International Nuclear Information System (INIS)

    Michutta, J.; Somsen, Ch.; Yawny, A.; Dlouhy, A.; Eggeler, G.

    2006-01-01

    The present study shows that multiple-step martensitic transformations can be observed in aged Ni-rich NiTi single crystals. Ageing of solution-annealed and water-quenched Ni-rich NiTi single crystals results in a homogeneous precipitation of coherent Ni 4 Ti 3 particles. When the interparticle spacing reaches a critical value (order of magnitude: 200 nm), three distinct transformation processes are observed on cooling from the high-temperature phase using differential scanning calorimetry and in situ transmission electron microscopy. The transformation sequence begins with the formation of R-phase starting from all precipitate/matrix interfaces (first step). The transformation continues with the formation of B19' and its subsequent growth along all precipitate/matrix interfaces (second step). Finally, the matrix in between the precipitates transforms to B19' (third step). Elementary transformation mechanisms which account for two- and three-step transformations in a system with small-scale microstructural heterogeneities were identified

  18. Synthesis and electrochemical characteristics of spinel LiMn2O4 via a precipitation spray-drying process

    International Nuclear Information System (INIS)

    Wu, H.M.; Tu, J.P.; Yuan, Y.F.; Li, Y.; Zhao, X.B.; Cao, G.S.

    2005-01-01

    Spinel LiMn 2 O 4 has been successfully synthesized using a precipitation spray-drying process. After the precursor was annealed at 750 deg. C for 10 h, the synthesized material was well-crystallized spinel particle, and exhibited uniform particle size distribution. From cyclic voltammetry results, there is an anomalous redox peaks (3.75/3.26 V). In the charge/discharge potential (versus Li) ranging from 3.2 to 4.5 V, it delivered a high initial discharge capacity of 123 mAh/g at a discharge rate of 60 μA/cm 2 (1/4 C rate). At a high discharge rate of 2.4 mA/cm 2 (10 C rate), the obtainable reversible capacity was 79 mAh/g. The simple procedure of precipitation spray-drying process is time and energy saving, and thus is promising for commercial application

  19. Computer simulation for precipitation process of θ (Ni3V) and γ' (Ni3Al) with microscopic phase-field method

    Institute of Scientific and Technical Information of China (English)

    HOU Hua; XU Hong; ZHAO Yu-hong

    2006-01-01

    With the microscopic phase-field model, the precipitation process of aged alloys was explored by computer simulation, which could clarify some discussional views on the precipitation mechanisms of alloys. The precipitation process of Ni75Al2.5V22.5 alloy was studied. From the simulated atomic pictures, calculated order parameters and volume fraction of different precipitates, it's found that the θ ordered phase precipitates earlier than γ' ordered phase by congruent ordering+spinodal decomposition mechanism and thus produces a nonstoicheometric θ single ordered phase. Then, the nonstoicheometric γ' phase is precipitated by a non-classical nucleation and growth mechanism at the APBS of θ phases. Meanwhile, both of them transform to stoicheometric ordered phases.

  20. The precipitation processes of Manaurite XM superalloy after 2000 hours of aging

    Directory of Open Access Journals (Sweden)

    W. Jasiński

    2008-03-01

    Full Text Available This papcr prcwnts thc results of invcsligations of rnicrostructurc and mcchnnicnl propcnics, In a slate of dclivcry. ancr 1000 anrl2(KKlh ofanncaling of supcralloy samples Manauritc XM ~akcnlr om a catalytic ccntrifugal cast pipc. Thc anncaling or rllc mntcrinl takcn fromcatal yric pipcs nt lhc tcmpcrarurc of 900 "C causes precipitation of intcrrnctallic phnscs in alloycd auacnitc matrix. Thcsc changcs afrcclthc pipcs' mcchnnical propcnies

  1. Using Extreme Tropical Precipitation Statistics to Constrain Future Climate States

    Science.gov (United States)

    Igel, M.; Biello, J. A.

    2017-12-01

    Tropical precipitation is characterized by a rapid growth in mean intensity as the column humidity increases. This behavior is examined in both a cloud resolving model and with high-resolution observations of precipitation and column humidity from CloudSat and AIRS, respectively. The model and the observations exhibit remarkable consistency and suggest a new paradigm for extreme precipitation. We show that the total precipitation can be decomposed into a product of contributions from a mean intensity, a probability of precipitation, and a global PDF of column humidity values. We use the modeling and observational results to suggest simple, analytic forms for each of these functions. The analytic representations are then used to construct a simple expression for the global accumulated precipitation as a function of the parameters of each of the component functions. As the climate warms, extreme precipitation intensity and global precipitation are expected to increase, though at different rates. When these predictions are incorporated into the new analytic expression for total precipitation, predictions for changes due to global warming to the probability of precipitation and the PDF of column humidity can be made. We show that strong constraints can be imposed on the future shape of the PDF of column humidity but that only weak constraints can be set on the probability of precipitation. These are largely imposed by the intensification of extreme precipitation. This result suggests that understanding precisely how extreme precipitation responds to climate warming is critical to predicting other impactful properties of global hydrology. The new framework can also be used to confirm and discount existing theories for shifting precipitation.

  2. CHARACTERIZATION OF A PRECIPITATE REACTOR FEED TANK (PRFT) SAMPLE FROM THE DEFENSE WASTE PROCESSING FACILITY (DWPF)

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, C.; Bannochie, C.

    2014-05-12

    A sample of from the Defense Waste Processing Facility (DWPF) Precipitate Reactor Feed Tank (PRFT) was pulled and sent to the Savannah River National Laboratory (SRNL) in June of 2013. The PRFT in DWPF receives Actinide Removal Process (ARP)/ Monosodium Titanate (MST) material from the 512-S Facility via the 511-S Facility. This 2.2 L sample was to be used in small-scale DWPF chemical process cell testing in the Shielded Cells Facility of SRNL. A 1L sub-sample portion was characterized to determine the physical properties such as weight percent solids, density, particle size distribution and crystalline phase identification. Further chemical analysis of the PRFT filtrate and dissolved slurry included metals and anions as well as carbon and base analysis. This technical report describes the characterization and analysis of the PRFT sample from DWPF. At SRNL, the 2.2 L PRFT sample was composited from eleven separate samples received from DWPF. The visible solids were observed to be relatively quick settling which allowed for the rinsing of the original shipping vials with PRFT supernate on the same day as compositing. Most analyses were performed in triplicate except for particle size distribution (PSD), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and thermogravimetric analysis (TGA). PRFT slurry samples were dissolved using a mixed HNO3/HF acid for subsequent Inductively Coupled Plasma Atomic Emission Spectroscopy (ICPAES) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) analyses performed by SRNL Analytical Development (AD). Per the task request for this work, analysis of the PRFT slurry and filtrate for metals, anions, carbon and base were primarily performed to support the planned chemical process cell testing and to provide additional component concentrations in addition to the limited data available from DWPF. Analysis of the insoluble solids portion of the PRFT slurry was aimed at detailed characterization of these solids (TGA, PSD

  3. Dissolution of copper and iron from malachite ore and precipitation of copper sulfate pentahydrate by chemical process

    Directory of Open Access Journals (Sweden)

    H. Kokes

    2014-03-01

    Full Text Available The present work describes an investigation of a chemical process for the recovery of copper and iron from malachite ore. For the dissolution of copper and iron, H2SO4 was employed as well as H2O2 as an oxidizing agent. The effects of reaction temperature and time, acid concentration, liquid-to-solid ratio and agitation rate on the copper and iron percentage were investigated. Following the steps of dissolving the copper and iron sulfate and filtering, iron (III hydroxide was precipitated by adjusting the pH level of the solution. Subsequently, copper sulfate pentahydrate was obtained by using various precipitants (i.e. ethanol, methanol and sulfuric acid.

  4. Early Stages of Precipitation Process in Al-(Mn-)Sc-Zr Alloy Characterized by Positron Annihilation

    KAUST Repository

    Vlach, Martin; Cizek, Jakub; Melikhova, Oksana; Stulikova, Ivana; Smola, Bohumil; Kekule, Tomas; Kudrnova, Hana; Gemma, Ryota; Neubert, Volkmar

    2015-01-01

    Thermal effects on the precipitation stages in as-cast Al-0.70 at. pct Mn-0.15 at. pct Sc-0.05 at. pct Zr alloy were studied. The role of lattice defects was elucidated by positron annihilation spectroscopy (lifetime and coincidence Doppler broadening) enabling investigation of solutes clustering at the atomic scale. This technique has never been used in the Al-Sc- and/or Al-Zr-based alloys so far. Studies by positron annihilation were combined with resistometry, hardness measurements, and microstructure observations. Positrons trapped at defects are preferentially annihilated by Sc electrons. Lifetime of trapped positrons indicates that Sc atoms segregate at dislocations. Maximum fraction of positrons annihilated by Sc electrons occurring at 453 K (180 °C) suggests that clustering of Sc bound with vacancies takes place. It is followed by peak of this fraction at 573 K (300 °C). A rise of the contribution of trapped positrons annihilated by Zr electrons starting at 513 K (240 °C) and attaining maximum also at 573 K (300 °C) confirms that Zr participates in precipitation of the Al3Sc particles already at these temperatures. The pronounced hardening at 573 K (300 °C) has its nature in the precipitation of the Al3Sc particles with a Zr-rich shell. The contribution of trapped positrons annihilated by Mn electrons was found to be negligible. © 2015, The Minerals, Metals & Materials Society and ASM International.

  5. Early Stages of Precipitation Process in Al-(Mn-)Sc-Zr Alloy Characterized by Positron Annihilation

    KAUST Repository

    Vlach, Martin

    2015-01-29

    Thermal effects on the precipitation stages in as-cast Al-0.70 at. pct Mn-0.15 at. pct Sc-0.05 at. pct Zr alloy were studied. The role of lattice defects was elucidated by positron annihilation spectroscopy (lifetime and coincidence Doppler broadening) enabling investigation of solutes clustering at the atomic scale. This technique has never been used in the Al-Sc- and/or Al-Zr-based alloys so far. Studies by positron annihilation were combined with resistometry, hardness measurements, and microstructure observations. Positrons trapped at defects are preferentially annihilated by Sc electrons. Lifetime of trapped positrons indicates that Sc atoms segregate at dislocations. Maximum fraction of positrons annihilated by Sc electrons occurring at 453 K (180 °C) suggests that clustering of Sc bound with vacancies takes place. It is followed by peak of this fraction at 573 K (300 °C). A rise of the contribution of trapped positrons annihilated by Zr electrons starting at 513 K (240 °C) and attaining maximum also at 573 K (300 °C) confirms that Zr participates in precipitation of the Al3Sc particles already at these temperatures. The pronounced hardening at 573 K (300 °C) has its nature in the precipitation of the Al3Sc particles with a Zr-rich shell. The contribution of trapped positrons annihilated by Mn electrons was found to be negligible. © 2015, The Minerals, Metals & Materials Society and ASM International.

  6. Simulation of the precipitation process of ordered intermetallic compounds in binary and ternary Ni-Al-based alloys by the phase-field model

    International Nuclear Information System (INIS)

    Hou Hua; Zhao Yuhong; Zhao Yuhui

    2009-01-01

    With the microscopic phase-field model, atomic-scale computer simulation programs for the precipitation mechanism of the ordered intermetallic compound γ' in binary Ni-15.5 at.%Al alloy, θ and γ' in ternary Ni 75 Al x V 25-x alloys were worked out based on the microscopic diffusion equation and non-equilibrium free energy. The simulation can be applied to the whole precipitation process and composition range. A prior assumptions on the new phase structure or transformation path was unnecessary, the possible non-equilibrium phases, atomic clustering and ordering could be described automatically, and atomic images, order parameters and volume fractions of precipitates were obtained. Computer simulation was performed systematically on the precipitation mechanism, precipitation sequence of θ and γ' in complicated system with ordering and clustering simultaneously. Through the simulated atomic images and chemical order parameters of precipitates, we can explain the complex precipitation mechanisms of θ (Ni 3 V) and γ' (Ni 3 Al) ordered phases. For the binary alloy, the precipitation mechanism of γ' phase has the characteristic of both non-classical nucleation and growth (NCNG) and congruent ordering and spinodal decomposition (COSD). For the ternary alloys, the precipitation characteristic of γ' phase transforms from NCNG to COSD gradually, otherwise, the precipitation characteristic of θ phase transforms from COSD to NCNG mechanism gradually

  7. Treatment of the effluent generated in conversion process of auc by precipitation

    International Nuclear Information System (INIS)

    Carvalho, E.F.U. de; Santos, L.R. dos; Riella, H.G.

    1988-01-01

    The purpose of this study is to provide a description for the treatment of generating effluent from Ammonium Uranyl Carbonate-AUC IPEN/CNEN-SP. This procedure describes the uranium recovery (200 mlU/1) by means of its precipitation with hidrogen peroxide at 50 0 C, pH 8,5 where results a yellow powder thought to be UO 4 2NH 3 2HF and a NH 4 F solution with an uranium concentration of 6-7mgU/1. The powder resulted was characterized by chemical analysis and X- Ray difraction techniques. (author) [pt

  8. Nuclear criticality safety bounding analysis for the in-tank-precipitation (ITP) process, impacted by fissile isotopic weight fractions

    Energy Technology Data Exchange (ETDEWEB)

    Bess, C.E.

    1994-04-22

    The In-Tank Precipitation process (ITP) receives High Level Waste (HLW) supernatant liquid containing radionuclides in waste processing tank 48H. Sodium tetraphenylborate, NaTPB, and monosodium titanate (MST), NaTi{sub 2}O{sub 5}H, are added for removal of radioactive Cs and Sr, respectively. In addition to removal of radio-strontium, MST will also remove plutonium and uranium. The majority of the feed solutions to ITP will come from the dissolution of supernate that had been concentrated by evaporation to a crystallized salt form, commonly referred to as saltcake. The concern for criticality safety arises from the adsorption of U and Pt onto MST. If sufficient mass and optimum conditions are achieved then criticality is credible. The concentration of u and Pt from solution into the smaller volume of precipitate represents a concern for criticality. This report supplements WSRC-TR-93-171, Nuclear Criticality Safety Bounding Analysis For The In-Tank-Precipitation (ITP) Process. Criticality safety in ITP can be analyzed by two bounding conditions: (1) the minimum safe ratio of MST to fissionable material and (2) the maximum fissionable material adsorption capacity of the MST. Calculations have provided the first bounding condition and experimental analysis has established the second. This report combines these conditions with canyon facility data to evaluate the potential for criticality in the ITP process due to the adsorption of the fissionable material from solution. In addition, this report analyzes the potential impact of increased U loading onto MST. Results of this analysis demonstrate a greater safety margin for ITP operations than the previous analysis. This report further demonstrates that the potential for criticality in the ITP process due to adsorption of fissionable material by MST is not credible.

  9. [Optimization of lime milk precipitation process of Lonicera Japonica aqueous extract based on quality by design concept].

    Science.gov (United States)

    Shen, Jin-Jing; Gong, Xing-Chu; Pan, Jian-Yang; Qu, Hai-Bin

    2017-03-01

    Design space approach was applied in this study to optimize the lime milk precipitation process of Lonicera Japonica (Jinyinhua) aqueous extract. The evaluation indices for this process were total organic acid purity and amounts of 6 organic acids obtained from per unit mass of medicinal materials. Four critical process parameters (CPPs) including drop speed of lime milk, pH value after adding lime milk, settling time and settling temperature were identified by using the weighted standardized partial regression coefficient method. Quantitative models between process evaluation indices and CPPs were established by a stepwise regression analysis. A design space was calculated by a Monte-Carlo simulation method, and then verified. The verification test results showed that the operation within the design space can guarantee the stability of the lime milk precipitation process. The recommended normal operation space is as follows: drop speed of lime milk of 1.00-1.25 mL•min⁻¹, pH value of 11.5-11.7, settling time of 1.0-1.2 h, and settling temperature of 10-20 ℃.. Copyright© by the Chinese Pharmaceutical Association.

  10. Study of the driving processes of frontal precipitation. Final report; Untersuchung der steuernden Prozesse bei der Niederschlagsbildung an Fronten. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Gross, P.; Kraus, H.

    1998-04-01

    The mesoscale dynamic processes, which contribute to the formation of precipitation in the vicinity of fronts, are investigated using dynamically initialized fields of the EM. Cross-sections perpendicular to 12 fronts elucidate, that the ageostrophic cross-frontal circulation is the dominant dynamical feature of a front. Precipitation develops in the upward branch of this secondary circulation closely related to the humidity budget including three-dimensional advection and source terms. The dynamical mechanisms (deformation- and shear-forcing), which dominate the development of both ageostrophic cross-frontal circulation and precipitation, are of very different type. Primitive models of fronts, like the polar front theory, don`t come up with this variability of the atmospheric forcing. (orig.) [Deutsch] Die mesoskaligen dynamischen Prozesse, die in der Umgebung von Fronten zur Bildung von Niederschlag fuehren, werden mit Hilfe von dynamisch initialisierten Feldern des EM untersucht. In Querschnitten senkrecht zu insgesamt 12 Fronten kristallisiert sich die ageostrophische Querzirkulation als bedeutendstes dynamisches Element einer Front heraus. Im aufsteigenden Ast dieser Sekundaerzirkulation entsteht, in engem Zusammenhang mit dem Haushalt der spezifischen Feuchte mit seinen besonders wichtigen Advektions- und Quelltermen, Niederschlag. Die dynamische Mechanismen (Deformations- und Scherungsforcing), die zur Ausbildung der Querzirkulation fuehren, sind in hohem Masse variabel. Dieser Mannigfaltigkeit des atmosphaerischen Antriebes werden einfache Frontmodelle, wie z.B. die Polarfronttheorie, nicht gerecht. (orig.)

  11. Processing, structure and magnetic properties correlation in co-precipitated Ca-ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abasht, Behzad, E-mail: abasht@gmail.com [Space Thruster Research Institute, Iranian Space Research Center, Tabriz (Iran, Islamic Republic of); Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Beitollahi, Ali; Mirkazemi, Seyyed Mohammad [Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2016-12-15

    La-substituted hexagonal calcium ferrite, Ca{sub 1−X}La{sub X}Fe{sub 12}O{sub 19} (x varies from 0 to 0.6 with the step of 0.2), was synthesized by applying co-precipitation method, in which the molar ratio of Fe{sup 3+}/(Ca{sup 2+}+La{sup 2+}) was 11. The ferrite precursors were prepared from aqueous solution of calcium nitrate, ferric nitrate and lanthanum nitrate by co-precipitation of calcium, iron and lanthanum ions by using an aqueous base of sodium hydroxide (1.5 M) at the pH of 14 and at room temperature. These precursors were calcinated with different amount of La at different temperature of 700, 1100 and 1200 °C for constant calcination time of 1 h in a static air atmosphere. Some tests such as simultaneous thermal analysis (STA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behavior, crystallographic properties, morphology and magnetic properties of the precursor powders which were calcinated at different temperatures. The powder XRD patterns of samples which consisted of La as dopant and were calcinated at 1200 °C for 1 h, indicates the formation of calcium hexaferrite and also α-Fe{sub 2}O{sub 3} besides Magnetoplumbite-phase (M-phase). However, the results showed that CaFe{sub 4}O{sub 7} and α-Fe{sub 2}O{sub 3} phases were formed in the sample with the same condition but without using any dopant. The results of SEM showed that the calcium hexaferrite particle were regular hexagonal platelets with the size range of 1–2 µm. The magnetic properties such as maximum magnetization (M{sub Max}), remanent magnetization (M{sub r}) and coercivity (H{sub c}) were measured from the hysteresis loops. Low values of coercive field (16.3 kA m{sup −1}) and maximum magnetization (50.6 A m{sup 2} kg{sup −1}) were obtained from calcium hexaferrite particle in optimum amount of La (X=0.4) which calcinated at the temperature of 1200 °C. - Highlights: • In this

  12. Dissolution of copper and iron from malachite ore and precipitation of copper sulfate pentahydrate by chemical process

    OpenAIRE

    H. Kokes; M.H. Morcali; E. Acma

    2014-01-01

    The present work describes an investigation of a chemical process for the recovery of copper and iron from malachite ore. For the dissolution of copper and iron, H2SO4 was employed as well as H2O2 as an oxidizing agent. The effects of reaction temperature and time, acid concentration, liquid-to-solid ratio and agitation rate on the copper and iron percentage were investigated. Following the steps of dissolving the copper and iron sulfate and filtering, iron (III) hydroxide was precipitated by...

  13. Numerical Simulation of Tuff Dissolution and Precipitation Experiments: Validation of Thermal-Hydrologic-Chemical (THC) Coupled-Process Modeling

    Science.gov (United States)

    Dobson, P. F.; Kneafsey, T. J.

    2001-12-01

    to evaluate larger-scale silica sealing observed in a portion of the Yellowstone geothermal system, a natural analog for the precipitation-experiment processes.

  14. Precipitation behavior during thin slab thermomechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength structural steels: The effect on mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Misra, R.D.K., E-mail: dmisra@louisiana.edu [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Jia, Z. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); O' Malley, R. [Nucor Steel Decatur, LLC Sheet Mill, 4301, Iverson Blvd., Trinity, AL 35673 (United States); Jansto, S.J. [CBMM-Reference Metals Company, 1000 Old Pond Road, Bridgeville, PA 15017 (United States)

    2011-11-15

    Highlights: {yields} Copper does not significantly influence toughness. {yields} Copper precipitation during aging occurs at dislocations. {yields} Precipitation of copper and carbides is mutually exclusive. - Abstract: We describe here the precipitation behavior of copper and fine-scale carbides during thermo-mechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength steels. During thermo-mechanical processing, precipitation of {epsilon}-copper occurs in polygonal ferrite and at the austenite-ferrite interface. In contrast, during isothermal aging, nucleation of {epsilon}-copper precipitation occurs at dislocations. In the three different chemistries investigated, the increase in strength associated with copper during aging results only in a small decrease in impact toughness, implying that copper precipitates do not seriously impair toughness, and can be considered as a viable strengthening element in microalloyed steels. Precipitation of fine-scale niobium carbides occurs extensively at dislocations and within ferrite matrix together with vanadium carbides. In the presence of titanium, titanium carbides act as a nucleus for niobium carbide formation. Irrespective of the nature of carbides, copper precipitates and carbides are mutually exclusive.

  15. Precipitation behavior during thin slab thermomechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength structural steels: The effect on mechanical properties

    International Nuclear Information System (INIS)

    Misra, R.D.K.; Jia, Z.; O'Malley, R.; Jansto, S.J.

    2011-01-01

    Highlights: → Copper does not significantly influence toughness. → Copper precipitation during aging occurs at dislocations. → Precipitation of copper and carbides is mutually exclusive. - Abstract: We describe here the precipitation behavior of copper and fine-scale carbides during thermo-mechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength steels. During thermo-mechanical processing, precipitation of ε-copper occurs in polygonal ferrite and at the austenite-ferrite interface. In contrast, during isothermal aging, nucleation of ε-copper precipitation occurs at dislocations. In the three different chemistries investigated, the increase in strength associated with copper during aging results only in a small decrease in impact toughness, implying that copper precipitates do not seriously impair toughness, and can be considered as a viable strengthening element in microalloyed steels. Precipitation of fine-scale niobium carbides occurs extensively at dislocations and within ferrite matrix together with vanadium carbides. In the presence of titanium, titanium carbides act as a nucleus for niobium carbide formation. Irrespective of the nature of carbides, copper precipitates and carbides are mutually exclusive.

  16. The influence of green microstructure and sintering parameters on precipitation process during copper-nickel-zinc ferrites sintering

    Directory of Open Access Journals (Sweden)

    Barba, Antonio

    2014-04-01

    Full Text Available Microstructural changes that occur during heat treatment of copper-nickel-zinc ferrites have been studied. The process of precipitation of the two types of crystals that occur during the sintering process has been analyzed. It is found that this process depends on dry relative density of the press specimens and on the following sintering parameters: sintering temperature, sintering time and cooling rate of the thermal cycle. Crystal precipitates characterization have been done by scanning electron microscopy (SEM, energy-dispersive X-ray (EDX analysis, X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS. These techniques have allowed to determine the nature of these crystals, which in this case correspond to zinc and copper oxides. It has been used two chemical reactions to explain the bulk precipitation and subsequent re-dissolution of these crystal precipitates during sintering.En este trabajo se han estudiado los cambios microestructurales que se producen durante el tratamiento térmico de las ferritas de cobre-níquel-cinc y se ha analizado el proceso de precipitación de los dos tipos de cristales que aparecen durante el proceso de sinterización. Se ha encontrado que este proceso depende de la densidad relativa en seco de las muestras compactadas y de las siguientes variables de la etapa de sinterización: temperatura y tiempo de sinterización y velocidad de enfriamiento. La caracterización de los cristales precipitados se ha realizado por microscopía electrónica de barrido (MEB, microanálisis por dispersión de energía de rayos X (EDX, difracción de rayos X (DRX, y espectroscopía de fotoelectrones de rayos X (XPS. Estas técnicas han permitido determinar la naturaleza de estos cristales, que en este caso corresponden a los óxidos de cinc y de cobre. Se han propuesto dos reacciones químicas que permiten explicar el proceso de precipitación y la posterior re-disolución de estos cristales precipitados durante la

  17. Preparation and characterization of protein isolate from Yellowfin tuna Thunnus albacares roe by isoelectric solubilization/precipitation process

    Directory of Open Access Journals (Sweden)

    Hyun Ji Lee

    2016-05-01

    Full Text Available Abstract Isoelectric solubilization/precipitation (ISP processing allows selective, pH-induced water solubility of proteins with concurrent separation of lipids and removal of materials not intended for human consumption such as bone, scales, skin, etc. Recovered proteins retain functional properties and nutritional value. Four roe protein isolates (RPIs from yellowfin tuna roe were prepared under different solubilization and precipitation condition (pH 11/4.5, pH 11/5.5, pH 12/4.5 and pH 12/5.5. RPIs contained 2.3–5.0 % moisture, 79.1–87.8 % protein, 5.6–7.4 % lipid and 3.0–3.8 % ash. Protein content of RPI-1 and RPI-2 precipitated at pH 4.5 and 5.5 after alkaline solubilization at pH 11, was higher than those of RPI-3 and RPI-4 after alkaline solubilization at pH 12 (P < 0.05. Lipid content (5.6–7.4 % of RPIs was lower than that of freeze-dried concentrate (10.6 %. And leucine and lysine of RPIs were the most abundant amino acids (8.8–9.4 and 8.5–8.9 g/100 g protein, respectively. S, Na, P, K as minerals were the major elements in RPIs. SDS-PAGE of RPIs showed bands at 100, 45, 25 and 15 K. Moisture and protein contents of process water as a 2’nd byproduct were 98.9–99.0 and 1.3–1.8 %, respectively. Therefore, yellowfin tuna roe isolate could be a promising source of valuable nutrients for human food and animal feeds.

  18. Two-stage precipitation of plutonium trifluoride

    International Nuclear Information System (INIS)

    Luerkens, D.W.

    1984-04-01

    Plutonium trifluoride was precipitated using a two-stage precipitation system. A series of precipitation experiments identified the significant process variables affecting precipitate characteristics. A mathematical precipitation model was developed which was based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter that can be used to control particle characteristics

  19. Nutrient management via struvite precipitation and recovery from various agroindustrial wastewaters: Process feasibility and struvite quality.

    Science.gov (United States)

    Taddeo, Raffaele; Honkanen, Mari; Kolppo, Kari; Lepistö, Raghida

    2018-04-15

    Improving environmental protection and finding sustainable and renewable resources of nutrients are core issues in circular bioeconomy. Thus, this study evaluated the efficiency of recovering struvite, MgNH 4 PO 4 ·6H 2 O, from different agro-industrial wastewaters (four highly loaded reject waters of anaerobically co-digested agro-industrial waste and a raw swine slurry) and assessed the quality of recovered struvite crystals and their reusability as fertilizer. The efficiency of crystallization (E c 40-80%) and amount of struvite in the precipitate (P p 55-94%) highly varied due to the characteristics of influent wastewaters, particularly to the content of competing elements, such as alkaline and heavy metals and total solids (TS). In particular, E c (94, 75, 61%) and P p (76, 66, 48%) decreased at increasing TS (0.57, 0.73, 0.99%), demonstrating the hindering effect of solid content on struvite recovery and quality. According to X-ray diffraction analysis, the structure of all isolated samples corresponded to crystalline, orthorhombic struvite, which exhibited high purity (32-48 g/kg d N, 114-132 g/kg d P, and 99-116 g/kg d Mg) containing only a few foreign elements, whose amount depended on the characteristics of the influent wastewater. All struvite contained other plant macronutrients (K, Ca) and many micronutrients (Fe, Na, Cu, Mn, Co, Zn) that further enhance its agronomic value. Therefore, this study showed that struvite can be successfully recovered from a wide range of highly loaded agroindustrial wastewaters, and that the quality of the recovered struvite could be suitable for reuse in agriculture. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Formation process of graphite film on Ni substrate with improved thickness uniformity through precipitation control

    Science.gov (United States)

    Kim, Seul-Gi; Hu, Qicheng; Nam, Ki-Bong; Kim, Mun Ja; Yoo, Ji-Beom

    2018-04-01

    Large-scale graphitic thin film with high thickness uniformity needs to be developed for industrial applications. Graphitic films with thicknesses ranging from 3 to 20 nm have rarely been reported, and achieving the thickness uniformity in that range is a challenging task. In this study, a process for growing 20 nm-thick graphite films on Ni with improved thickness uniformity is demonstrated and compared with the conventional growth process. In the film grown by the process, the surface roughness and coverage were improved and no wrinkles were observed. Observations of the film structure reveal the reasons for the improvements and growth mechanisms.

  1. Active liquid treatment by a combination of precipitation and membrane processes

    International Nuclear Information System (INIS)

    Gutman, R.G.; Cumming, I.W.; Williams, G.H.

    1986-08-01

    New ultrafiltration processes developed for the treatment of low and medium active radioactive wastes, were applied successfully to a variety of simulated and real wastes, including magnesium alloy clad spent storage fuel pond waters, reprocessing plant solvent wash liquors, plutonium production effluents and mixed site effluents. After initial laboratory scale feasibility experiments the process was scaled up successfully, using a variety of different ultrafiltration modules. The information accumulated on membrane performance, membrane fouling and flux restoration techniques, and ancillary equipment performance was used to design a much larger demonstration pilot plant. This plant has been constructed and is now processing continuously each day over 1m 3 of a real radioactive effluent. (author)

  2. Process-model simulations of cloud albedo enhancement by aerosols in the Arctic

    Science.gov (United States)

    Kravitz, Ben; Wang, Hailong; Rasch, Philip J.; Morrison, Hugh; Solomon, Amy B.

    2014-01-01

    A cloud-resolving model is used to simulate the effectiveness of Arctic marine cloud brightening via injection of cloud condensation nuclei (CCN), either through geoengineering or other increased sources of Arctic aerosols. An updated cloud microphysical scheme is employed, with prognostic CCN and cloud particle numbers in both liquid and mixed-phase marine low clouds. Injection of CCN into the marine boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. Albedo increases are stronger for pure liquid clouds than mixed-phase clouds. Liquid precipitation can be suppressed by CCN injection, whereas ice precipitation (snow) is affected less; thus, the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. CCN injection into a clean regime results in a greater albedo increase than injection into a polluted regime, consistent with current knowledge about aerosol–cloud interactions. Unlike previous studies investigating warm clouds, dynamical changes in circulation owing to precipitation changes are small. According to these results, which are dependent upon the representation of ice nucleation processes in the employed microphysical scheme, Arctic geoengineering is unlikely to be effective as the sole means of altering the global radiation budget but could have substantial local radiative effects. PMID:25404677

  3. Biochemical process of ureolysis-based microbial CaCO3 precipitation and its application in self-healing concrete.

    Science.gov (United States)

    Xu, Jing; Wang, Xianzhi; Wang, Binbin

    2018-04-01

    Urea hydrolysis has already been considered as the most effective pathway for microbially induced CaCO 3 precipitation (MICP). The present work first studied the combination of several key factors including initial pH, temperature, and dosage of urea, which contribute to the biochemical process of MICP. Under an amiable condition of pH and temperature, the dosage of urea has a significant impact on the rate of urea degradation and CaCO 3 precipitation. A bacteria-based self-healing system was developed by loading healing agents on ceramsite carriers. The self-healing efficiency was evaluated by visual inspection on crack closure, compressive strength regain, and capillary water absorption. A preferable healing effectiveness was obtained when the bacteria and organic nutrients were co-immobilized in carriers. Image analysis showed that cracks up to 273 μm could be healed with a crack closure ratio of 86% in 28 days. The compressive strength regain increased 24% and the water absorption coefficient decreased 27% compared to the reference. The findings indicated a promising application of ureolysis-based MICP in restoring the mechanical properties and enhancing the durability of concrete.

  4. Microbially induced carbonate precipitation (MICP) by denitrification as ground improvement method - Process control in sand column experiments

    Science.gov (United States)

    Pham, Vinh; van Paassen, Leon; Nakano, Akiko; Kanayama, Motohei; Heimovaara, Timo

    2013-04-01

    Calcite precipitation induced by microbes has been proven to be efficient in stabilizing granular soils, especially with urea hydrolysis, as it has been successfully demonstrated in a pilot application 2010. However, as a byproduct highly concentrated ammonium chloride (NH4Cl) solution is produced, which has to be removed and disposed and forms a significant disadvantage of the technique that makes an alternative process like denitrification preferred. The proof of principle of microbially induced calcite precipitation (MICP) by denitrification has been demonstrated by Van Paassen et al (2010) who suggested that instead of producing waste as a byproduct, different pre-treated waste streams could be used as substrates for in situ growth of denitrifying bacteria and simultaneous cementation without producing waste to be removed. In this study sand column experiments are performed in which calcium carbonate was successfully precipitated by indigenous denitrifying micro-organisms, which were supplied weekly with a pulse of a substrate solution containing calcium acetate and calcium nitrate. Besides the production of calcite and the growth of bacteria in biofilms, the reduction of nitrate resulted in the production of (nitrogen) gas. It was observed that this gas partly fills up the pore space and consequently contributed to a reduction of the permeability of the treated sand. The presence of gas in the pore space affected the flow of the injected substrates and influenced to the distribution of calcium carbonate. The effect of the mean particle size (D50) on the flow and transport of solutes and gas in the porous media has been evaluated by treating several columns with varying grain size distribution and comparing the change in permeability after each incubation period and analyzing the distribution of the gas throughout the columns using X-ray computed tomography (CT) scanning. The present results show that there is a considerable decrease of permeability - a

  5. Frequency of deflagration in the in-tank precipitation process tanks due to loss of nitrogen purge system

    International Nuclear Information System (INIS)

    Jansen, J.M.; Mason, C.L.; Olsen, L.M.; Shapiro, B.J.; Gupta, M.K.; Britt, T.E.

    1994-01-01

    High-level liquid wastes (HLLW) from the processing of nuclear material at the Savannah River Site (SRS) are stored in large tanks in the F- and H-Area tank farms. The In-Tank Precipitation (ITP) process is one step in the processing and disposal of HLLW. The process hazards review for the ITP identified the need to implement provisions that minimize deflagration/explosion hazards associated with the process. The objective of this analysis is to determine the frequency of a deflagration in Tank 48 and/or 49 due to nitrogen purge system failures (including external events) and coincident ignition source. A fault tree of the nitrogen purge system coupled with ignition source probability is used to identify dominant system failures that contribute to the frequency of deflagration. These system failures are then used in the recovery analysis. Several human actions, recovery actions, and repair activities are identified that reduce total frequency. The actions are analyzed and quantified as part of a Human Reliability Analysis (HRA). The probabilities of failure of these actions are applied to the fault tree cutsets and the event trees

  6. Laboratory Tests on Post-Filtration Precipitation in the WTP Pretreatment Process

    International Nuclear Information System (INIS)

    Russell, Renee L.; Peterson, Reid A.; Rinehart, Donald E.; Crum, Jarrod V.

    2009-01-01

    Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, 'Undemonstrated Leaching Processes,' of the External Flowsheet Review Team (EFRT) issue response plan (Barnes et al. 2006). The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. A simplified flow diagram of the PEP system is shown in Figure 1.1. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP; and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP; vessels UFP-VSL-00001A and B in the WTP PTF).

  7. The fabrication process of ceramic grade UO2 powder via fluorid system AUC and the treatment on AUC precipitation filtrate

    International Nuclear Information System (INIS)

    Liu Jinhong; Xu Kui; Li Zhiwan; Yi Wei; Tang Yueming; Li Guangrong; Lei Maolin; Cui Chuanjiang

    2006-10-01

    It is described about the technology of fabricating AUC powder by Circum-fluence Precipitation Reactor with Gas (CPRG) from UF 6 hydrolyzed liquid, manufacturing nuclear pure ceramic grade UO 2 powder via fluorid system AUC process with fluidized bed method, recovering U(VI) with ion exchange resin, depositing fluorin in an outflow of effusion wastewater from the ion exchange using calces. The primary control parameters on the fabricating AUC powder is study, it is discussed to character difference of AUC powder between fluorid system and nitrate. Result show that the composing the manufacture AUC powder is invariable by CORG, and that the AUC quality is consistent, and that by decomposition and reduction of AUC and stabilization of UO 2 powder with fluidized bed, through optimum technological parameters, the excellent UO 2 powder is obtained on the quality. (authors)

  8. K Basin Sludge Conditioning Process Testing Partitioning of PCBs in Dissolver Solution After Neutralization/Precipitation (Caustic Adjustment)

    International Nuclear Information System (INIS)

    Schmidt, A.J.; Thornton, B.M.; Hoppe, E.W.; Mong, G.M.; Silvers, K.L.; Slate, S.O.

    1999-01-01

    The purpose of the work described in this report was to gain a better understanding of how PCB congeners present in a simulated K Basin sludge dissolver solution will partition upon neutralization and precipitation (i.e., caustic adjustment). In a previous study (Mong et al. 1998),the entire series of sludge conditioning steps (acid dissolution, filtration, and caustic adjustment) were examined during integrated testing. In the work described here, the caustic adjustment step was isolated to examine the fate of PCBs in more detail within this processing step. For this testing, solutions of dissolver simulant (containing no solids) with a known initial concentration of PCB congeners were neutralized with caustic to generate a clarified supernatant and a settled sludge phase. PCBs were quantified in each phase (including the PCBs associated with the test vessel rinsates), and material balance information was collected

  9. Numerical Estimation of the Formation Process of Anthropogenic Precipitation in the Atmosphere

    Directory of Open Access Journals (Sweden)

    Gvozdyakov Dmitriy V.

    2017-01-01

    Full Text Available The processes of condensation of sulfur trioxide SO3 and water vapor H2O. Sulfuric anhydride is formed in flues of thermal power plants (TPP by partial oxidation of SO2 (up to 5 % of the total SO2 from the combustion of high-sulfur fuels, and belongs to a class of mild-hazard products. Sulfuric anhydride in the interaction with water vapor, which refers to greenhouse gases, under certain conditions, it forms sulfuric acid.

  10. Treatment of aqueous outflows by complexation in micellar media and precipitation with a sol-gel process

    International Nuclear Information System (INIS)

    Lavaud, Cyril

    2013-01-01

    Being able to deal with aqueous outflows from treatment sites in the Hague is a major environmental issue. These outflows are contaminated with organic substances and elements with residual radioactivity. This work deals with the development and optimization of the process of de-polluting, and we aim at removing all pollution from the outflow, and produce a final waste compatible with traditional conditioning matrices in the nuclear area. The separation process consists of two steps: dissolving the pollution in the surfactants micelles, and precipitating a mineral phase via sol-gel transition. Within this thesis, only pollution originating from radionuclides is studied. During the first step, our strategy is to use complexing molecules able to interact with ions and to form mainly solvable complexes at the core of surfactant micelles. Thereafter, the second step consisted to add silica precursor which, after hydrolyse and polycondensation, makes it possible to aggregate those micelles that contain complexes together, and to form a silica phase which precipitates in an in-situ fashion. The goal to de-pollute the outflow was achieved, and the final waste thus produced is a silica powder that contains the micelles and the pollution which, after calcination, is compatible with conditioning matrices such as glass or concrete. A reference system for which the separation process is optimal was defined throughout various studies. This system contains a non-ionic surfactant (P123), an ion that surrogates radionuclides (neodymium), a complexing agent (HDEHP) and a silica precursor (TEOS). Hence, this system was further studied in order to broaden the application scope of the separation process, as well as to understand the mechanisms involved, during the complexation of the ions and the micellar solubilization and during the formation of the silica powder. This study was performed using diffusion, imaging and spectrometry techniques.To conclude, the alternative de

  11. Precipitation of Scale-Forming Species During Processing of High-Level Wastes

    International Nuclear Information System (INIS)

    Mattigod, Shas V.; Hobbs, David T.; Parker, Kent E.; McCready, David E.

    2004-01-01

    High-level wastes from fuel-reprocessing operations are being evaporated at the DOE Savannah River Site to concentrate the liquids to about 30 to 40% of their original volume before they are discharged into a holding tank. Recently, the operation of one of the evaporators became progressively more difficult due to more frequent buildup of limited solubility aluminosilicate compounds resulting in the shutdown of the evaporator. Our research objectives were to identify and characterize the chemistry and microstructure of these scale-forming species and to determine the kinetics of formation and transformation of these solids under evaporator conditions. The data we obtained from these tests showed that hydroxide concentration and process temperature are the key factors that control the rate of formation and transformation of the scale forming solids such as zeolite A, sodalite and cancrinite

  12. Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase solvent precipitation process.

    Science.gov (United States)

    Nagaraja, Ashvin T; You, Yil-Hwan; Choi, Jeong-Wan; Hwang, Jin-Ha; Meissner, Kenith E; McShane, Michael J

    2016-03-15

    The layer-by-layer modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles was studied in an effort to illustrate effective means to overcome practical issues in handling and performing surface modification of such extremely small materials. To accomplish this, each layer deposition cycle was separated into a multi-step process wherein solution pH was controlled in two distinct phases of polyelectrolyte adsorption and centrifugation. Additionally, a solvent precipitation step was introduced to make processing more amenable by concentrating the sample and exchanging solution pH before ultracentrifugation. The pH-dependent assembly on gold nanoparticles was assessed after each layer deposition cycle by monitoring the plasmon peak absorbance location, surface charge, and the percentage of nanoparticles recovered. The selection of solution pH during the adsorption phase was found to be a critical parameter to enhance particle recovery and maximize surface charge when coating with weak polyelectrolytes. One bilayer was deposited with a high yield and the modified particles exhibited enhanced colloidal stability across a broad pH range and increased ionic strength. These findings support the adoption of this multi-step processing approach as an effective and generalizable approach to improve stability of high surface curvature particles. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Electrification of precipitating systems over the Amazon: Physical processes of thunderstorm development

    Science.gov (United States)

    Albrecht, Rachel I.; Morales, Carlos A.; Silva Dias, Maria A. F.

    2011-04-01

    This study investigated the physical processes involved in the development of thunderstorms over southwestern Amazon by hypothesizing causalities for the observed cloud-to-ground lightning variability and the local environmental characteristics. Southwestern Amazon experiences every year a large variety of environmental factors, such as the gradual increase in atmospheric moisture, extremely high pollution due to biomass burning, and intense deforestation, which directly affects cloud development by differential surface energy partition. In the end of the dry period it was observed higher percentages of positive cloud-to-ground (+CG) lightning due to a relative increase in +CG dominated thunderstorms (positive thunderstorms). Positive (negative) thunderstorms initiated preferentially over deforested (forest) areas with higher (lower) cloud base heights, shallower (deeper) warm cloud depths, and higher (lower) convective potential available energy. These features characterized the positive (negative) thunderstorms as deeper (relatively shallower) clouds, stronger (relatively weaker) updrafts with enhanced (decreased) mixed and cold vertically integrated liquid. No significant difference between thunderstorms (negative and positive) and nonthunderstorms were observed in terms of atmospheric pollution, once the atmosphere was overwhelmed by pollution leading to an updraft-limited regime. However, in the wet season both negative and positive thunderstorms occurred during periods of relatively higher aerosol concentration and differentiated size distributions, suggesting an aerosol-limited regime where cloud electrification could be dependent on the aerosol concentration to suppress the warm and enhance the ice phase. The suggested causalities are consistent with the invoked hypotheses, but they are not observed facts; they are just hypotheses based on plausible physical mechanisms.

  14. Design of the Precipitation Process for Ni-Al Alloys with Optimal Mechanical Properties: A Phase-Field Study

    Science.gov (United States)

    Ta, Na; Zhang, Lijun; Du, Yong

    2014-04-01

    An attempt to design the heat treatment schedule for binary Ni-Al alloys with optimal mechanical properties was made in the present work. A series of quantitative three-dimensional (3-D) phase-field simulations of microstructure evolution in Ni-Al alloys during the precipitation process were first performed using MICRESS (MICRostructure Evolution Simulation Software) package developed in the formalism of the multi-phase field model. The coupling to CALPHAD (CALculation of PHAse Diagram) thermodynamic and atomic mobility databases was realized via TQ interface. Moreover, the temperature-dependent lattice misfits and elastic constants were utilized for simulation. The effect of the alloy composition and aging temperature on microstructure evolution was extensively studied with the aid of statistical analysis. After that, an evaluation function was proposed for evaluating the optimal heat treatment schedule by choosing the phase fraction, grain size, and shape factor of γ' precipitate as the evaluation indicators. Based on 50 groups of phase-field-simulated and experimental microstructure information, as well as the proposed evaluation function, the optimal alloy composition, aging temperature, and aging time for binary Ni-Al alloy with optimal mechanical properties were finally chosen. The successful application in the present Ni-Al alloys indicates that it is possible to design the optimal alloy composition and heat treatment for other binary and even multicomponent alloys with optimal mechanical properties based on the evaluation function and the sufficient microstructure information. Additionally, the combination of the present method and the key experiments can definitely accelerate the material design and improve the efficiency and accuracy.

  15. Effect of precipitates on microstructures and properties of forged Mg-10Gd-2Y-0.5Zn-0.3Zr alloy during ageing process

    International Nuclear Information System (INIS)

    Han, X.Z.; Xu, W.C.; Shan, D.B.

    2011-01-01

    Highlights: · The effect of forging process on microstructure evolution and mechanical properties of Magnesium alloy with rare earth was investigated. · The optimal mechanical properties of the alloy with high strength and enough elongation were obtained after forging and ageing process. · The strength improvement of the alloy after forging and ageing process mainly results from the precipitation of 14H-type LPSO phase. · Strengthening mechanism of the alloy is controlled by the precipitation of β' and 14H-type LPSO phases which can inhibit sliding of dislocations and growth of grain boundaries. - Abstract: The precipitate behavior during forging and ageing process of Mg-10Gd-2Y-0.5Zn-0.3Zr alloy has been investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mechanical properties of the alloy after forging and ageing process have been evaluated using Vickers hardness and room-temperature tensile tests. The results show that precipitation of 14H-type long period stacking order (LPSO) phase is the main strengthening phase in the as-forged alloy. The LPSO phase and refinement of grains contribute to the strength improvement of the alloy after forging process. The optimal mechanical properties of the alloy are obtained when it is aged at 200 deg. C for 60 h, which mainly owes to the precipitation of large amounts of β' and 14H-type LPSO phases on the α-Mg matrix. The growth of secondary phases, widening of soft precipitate free zones and coarsening of grains during subsequent ageing process at higher temperature lead to the decrease of mechanical properties of the alloy.

  16. Cerium oxalate precipitation

    International Nuclear Information System (INIS)

    Chang, T.P.

    1987-02-01

    Cerium, a nonradioactive, common stand-in for plutonium in development work, has been used to simulate several plutonium precipitation processes at the Savannah River Laboratory. There are similarities between the plutonium trifluoride and the cerium oxalate precipitations in particle size and extent of plating, but not particle morphology. The equilibrium solubility, precipitation kinetics, particle size, extent of plating, and dissolution characteristics of cerium oxalate have been investigated. Interpretations of particle size and plating based on precipitation kinetics (i.e., nucleation and crystal growth) are presented. 16 refs., 7 figs., 6 tabs

  17. PRECIPITATION OF PROTACTINIUM

    Science.gov (United States)

    Moore, R.L.

    1958-07-15

    An lmprovement in the separation of protactinium from aqueous nitric acid solutions is described. 1t covers the use of lead dioxide and tin dioxide as carrier precipitates for the protactinium. In carrying out the process, divalent lead or divalent tin is addcd to the solution and oxidized, causing formation of a carrier precipitate of lead dioxide or stannic oxide, respectively.

  18. Influence of Y2BaCuO5 precipitates on the current density of melt processed YBa2Cu3Ox superconductor

    International Nuclear Information System (INIS)

    Salama, K.; Selvamanickam, V.

    1992-01-01

    YBa 2 Cu 3 O x superconductors fabricated by melt processing methods have been shown to exhibit current density around 10 5 A/cm 2 at 77 K. Since YBa 2 Cu 3 O x decomposes peritectically above 1000 C, more than 50 vol. % of Y 2 BaCuO 5 (211) precipitates are formed during the incongruent melting. Even under stringent slow cooling conditions, a significant amount of these precipitates remain unreacted with the liquid and are left embedded in the long 123 grains. The potential of these precipitates as flux pinning sites has been investigated extensively, but remains controversial. In this study, we have performed transport current density measurements on melt processed YBa 2 Cu 3 O x superconductor prepared with varying amount of 211 precipitates. The current density measurements were performed in magnetic fields up to 1.5 T at 77 K with the field aligned at different angles to the a-b plane. The results provided in this paper show that Jc decreases monotonically with increasing amount of 211, irrespective of the angle between the field and the a-b plane indicating the absence of significant pinning by 211 precipitates in melt processed YBa 2 Cu 3 O x superconductor

  19. 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.

    Science.gov (United States)

    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

  20. Characterization of a calcium phosphate cement based on alpha-tricalcium phosphate obtained by wet precipitation process

    International Nuclear Information System (INIS)

    Thurmer, M.B.; Diehl, C.E.; Vieira, R.S.; Coelho, W.T.G.; Santos, L.A.

    2012-01-01

    There are several systems of calcium phosphate cements being studied. Those based on alpha-tricalcium phosphate are of particular interest. After setting they produce calcium deficient hydroxyapatite similar to bone like hydroxyapatite. This work aims to obtain alpha-tricalcium phosphate powders by the wet precipitation process, using calcium nitrate and phosphoric acid as reagents. This powder was characterized by infrared spectroscopy, X-ray diffraction and particle size distribution. In order to prepare the calcium phosphate cement, the powder was mixed with an accelerator in an aqueous solution. The mechanical properties of the cement were assessed and it was evaluated by means of apparent density, X-ray diffraction and scanning electron microscopy. The described method produced crystalline alpha-tricalcium phosphate as the major phase. The calcium phosphate cement showed high values of compression strength (50 MPa). The soaking of the cement in a simulated body fluid (SBF) formed a layer of hydroxyapatite like crystals in the surface of the samples. (author)

  1. The utilization of waste by-products for removing silicate from mineral processing wastewater via chemical precipitation.

    Science.gov (United States)

    Kang, Jianhua; Sun, Wei; Hu, Yuehua; Gao, Zhiyong; Liu, Runqing; Zhang, Qingpeng; Liu, Hang; Meng, Xiangsong

    2017-11-15

    This study investigates an environmentally friendly technology that utilizes waste by-products (waste acid and waste alkali liquids) to treat mineral processing wastewater. Chemical precipitation is used to remove silicate from scheelite (CaWO 4 ) cleaning flotation wastewater and the waste by-products are used as a substitute for calcium chloride (CaCl 2 ). A series of laboratory experiments is conducted to explain the removal of silicate and the characterization and formation mechanism of calcium silicate. The results show that silicate removal reaches 90% when the Ca:Si molar ratio exceeds 1.0. The X-ray diffraction (XRD) results confirm the characterization and formation of calcium silicate. The pH is the key factor for silicate removal, and the formation of polysilicic acid with a reduction of pH can effectively improve the silicate removal and reduce the usage of calcium. The economic analysis shows that the treatment costs with waste acid (0.63 $/m 3 ) and waste alkali (1.54 $/m 3 ) are lower than that of calcium chloride (2.38 $/m 3 ). The efficient removal of silicate is confirmed by industrial testing at a plant. The results show that silicate removal reaches 85% in the recycled water from tailings dam. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Continuous plutonium(IV) oxalate precipitation, filtration, and calcination process. [From product streams from Redox, Purex, or Recuplex solvent extraction plants

    Energy Technology Data Exchange (ETDEWEB)

    Beede, R L

    1956-09-27

    A continuous plutonium (IV) oxalate precipitation, filtration, and calcination process has been developed. Continuous and batch decomposition of the oxalate in the filtrates has been demonstrated. The processes have been demonstrated in prototype equipment. Plutonium (IV) oxalate was precipitated continuously at room temperature by the concurrent addition of plutonium (IV) nitrate feed and oxalic acid into the pan of a modified rotary drum filter. The plutonium (IV) oxalate was calcined to plutonium dioxide, which could be readily hydrofluorinated. Continuous decomposition of the oxalate in synthetic plutonium (IV) oxalate filtrates containing plutonium (IV) oxalate solids was demonstrated using co-current flow in a U-shaped reactor. Feeds containing from 10 to 100 g/1 Pu, as plutonium (IV) nitrate, and 1.0 to 6.5 M HNO/sub 3/, respectively, can be processed. One molar oxalic acid is used as the precipitant. Temperatures of 20 to 35/sup 0/C for the precipitation and filtration are satisfactory. Plutonium (IV) oxalate can be calcined at 300 to 400/sup 0/C in a screw-type drier-calciner to plutonium dioxide and hydrofluorinated at 450 to 550/sup 0/C. Plutonium dioxide exceeding purity requirements has been produced in the prototype equipment. Advantages of continuous precipitation and filtration are: uniform plutonium (IV) oxalate, improved filtration characteristics, elimination of heating and cooling facilities, and higher capacities through a single unit. Advantages of the screw-type drier-calciner are the continuous production of an oxide satisfactory for feed for the proposed plant vibrating tube hydrofluorinator, and ease of coupling continuous precipitation and filtration to this proposed hydrofluorinator. Continuous decomposition of oxalate in filtrates offers advantages in decreasing filtrate storage requirements when coupled to a filtrate concentrator. (JGB)

  3. A Guide for Developing Standard Operating Job Procedures for the Tertiary Chemical Treatment - Lime Precipitation Process Wastewater Treatment Facility. SOJP No. 6.

    Science.gov (United States)

    Petrasek, Al, Jr.

    This guide describes the standard operating job procedures for the tertiary chemical treatment - lime precipitation process of wastewater treatment plants. Step-by-step instructions are given for pre-start up, start-up, continuous operation, and shut-down procedures. In addition, some theoretical material is presented along with some relevant…

  4. Investigation of Relationship Between Hydrologic Processes of Precipitation, Evaporation and Stream Flow Using Linear Time Series Models (Case study: Western Basins of Lake Urmia

    Directory of Open Access Journals (Sweden)

    M. Moravej

    2016-02-01

    Full Text Available Introduction: Studying the hydrological cycle, especially in large scales such as water catchments, is difficult and complicated despite the fact that the numbers of hydrological components are limited. This complexity rises from complex interactions between hydrological components and environment. Recognition, determination and modeling of all interactive processes are needed to address this issue, but it's not feasible for dealing with practical engineering problems. So, it is more convenient to consider hydrological components as stochastic phenomenon, and use stochastic models for modeling them. Stochastic simulation of time series models related to water resources, particularly hydrologic time series, have been widely used in recent decades in order to solve issues pertaining planning and management of water resource systems. In this study time series models fitted to the precipitation, evaporation and stream flow series separately and the relationships between stream flow and precipitation processes are investigated. In fact, the three mentioned processes should be modeled in parallel to each other in order to acquire a comprehensive vision of hydrological conditions in the region. Moreover, the relationship between the hydrologic processes has been mostly studied with respect to their trends. It is desirable to investigate the relationship between trends of hydrological processes and climate change, while the relationship of the models has not been taken into consideration. The main objective of this study is to investigate the relationship between hydrological processes and their effects on each other and the selected models. Material and Method: In the current study, the four sub-basins of Lake Urmia Basin namely Zolachay (A, Nazloochay (B, Shahrchay (C and Barandoozchay (D were considered. Precipitation, evaporation and stream flow time series were modeled by linear time series. Fundamental assumptions of time series analysis namely

  5. Precipitation and measurements of precipitation

    NARCIS (Netherlands)

    Schmidt, F.H.; Bruin, H.A.R. de; Attmannspacher, W.; Harrold, T.W.; Kraijenhoff van de Leur, D.A.

    1977-01-01

    In Western Europe, precipitation is normal phenomenon; it is of importance to all aspects of society, particularly to agriculture, in cattle breeding and, of course, it is a subject of hydrological research. Precipitation is an essential part in the hydrological cycle. How disastrous local

  6. Radioactive Air Emissions Notice of Construction for the Magnesium Hydroxide Precipitation Process at the Plutonium Finishing Plant (PFP)

    International Nuclear Information System (INIS)

    JANSKY, M.T.

    1999-01-01

    The following description and any attachments and references are provided to the Washington State Department of Health (WDOH), Division of Radiation Protection, Air Emissions and Defense Waste (WAC) 246-247, Radiation Protection-Air Emissions. The WAC 246-247-060, ''Applications, registration, and licensing'', states ''This section describes the information requirements for approval to construct, modify, and operate an emission unit. Any NOC requires the submittal of information listed in Appendix A.'' Appendix A (WAC 246-247-1 10) lists the requirements that must be addressed. Additionally, the following description, attachments and references are provided to the US Environmental Protection Agency (EPA) as an NOC, in accordance with Title 40, Code of Federal Regulations (CFR), Part 61, ''National Emission Standards for Hazardous Air Pollutants.'' The information required for submittal to the EPA is specified in 40 CFR 61.07. The potential emissions from this activity are estimated to provide greater than 0.1 millirem per year total effective dose equivalent (TEDE) to the hypothetical offsite maximally exposed individual (MEI), and commencement is needed within a short time. Therefore, this application also is intended to provide notification of the anticipated date of initial startup in accordance with the requirement listed in 40 CFR 61.09(a)(1), and it is requested that approval of this application also will constitute EPA acceptance of this initial startup notification. Written notification of the actual date of initial startup, in accordance with the requirement listed in 40 CFR 61.09(a)(2) will be provided at a later date. This NOC covers the activities associated with the Construction and operation activities involving the magnesium hydroxide precipitation process of plutonium solutions within the Plutonium Finishing Plant (PFP)

  7. Performance of Separation Processes for Precipitated Calcium Carbonate Produced with an Innovative Method from Steelmaking Slag and Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Teir, Sebastian, E-mail: sebastian.teir@vtt.fi [VTT Technical Research Centre of Finland Ltd., Espoo (Finland); Auvinen, Toni [Outotec Dewatering Technology Center, Lappeenranta (Finland); Said, Arshe [Department of Energy Technology, School of Engineering, Aalto University, Espoo (Finland); Kotiranta, Tuukka; Peltola, Heljä [Outotec Research Center, Pori (Finland)

    2016-02-22

    In this work, experiments were performed to determine the filterability of calcium carbonate produced with an alternative calcium carbonate production concept. The concept uses steelmaking slag as raw material and has potential to fix CO{sub 2} emissions and utilize steelmaking slag, simultaneously. As calcium carbonate is precipitated in a solution containing ammonium chloride, calcium chloride, and ammonia, the product needs to be washed and hence filtered. In this work, different separation processes, including washing, filtering, and drying, were tested on two calcium carbonate slurries produced from steel converter slag and CO{sub 2} by a laboratory-scale pilot facility, with the aim of obtaining a solid product with a low chloride content using a minimum amount of washing water. The order of maximum filtration rates achievable of the calcium carbonate slurries was determined by experimental work. The tests included pressure filtration and vacuum filtration and the test series contained altogether 21 different filtration cycles with varying combinations of filtering, washing, and drying steps. The filtered cakes were analyzed by their residual moisture content, chloride content, and conductivity, and the filtrates by their residual solids content, chloride content, and conductivity. Pressure filtration gave a high capacity (400–460 kg/m{sup 2}h) and a low cake residual moisture content (12–14 wt-%). Vacuum filtration gave slightly higher filtration rates (500–610 kg/m{sup 2}h at the lowest residual chloride contents of the cakes), but the cake residual moisture also stayed higher (25–26 wt-%). As the vacuum filtration tests used a filter cloth with higher permeability than that of the pressure filtration tests, a slightly higher filtration rate was expected. However, both filtration technologies seem suitable for filtering and washing calcium carbonate prepared with the studied method as a residual chloride content as low as 10 ppm of the filtered

  8. Precipitous Birth

    Directory of Open Access Journals (Sweden)

    Jennifer Yee

    2017-09-01

    Full Text Available Audience: This scenario was developed to educate emergency medicine residents on the management of a precipitous birth in the emergency department (ED. The case is also appropriate for teaching of medical students and advanced practice providers, as well as reviewing the principles of crisis resource management, teamwork, and communication. Introduction: Patients with precipitous birth require providers to manage two patients simultaneously with limited time and resources. Crisis resource management skills will be tested once baby is delivered, and the neonate will require assessment for potential neonatal resuscitation. Objectives: At the conclusion of the simulation session, learners will be able to manage women who have precipitous deliveries, as well as perform neonatal assessment and management. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session and lecture on precipitous birth management and neonatal evaluation.

  9. An Improved Plutonium Trifluoride Precipitation Flowsheet

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, H.D.

    2001-06-26

    This report discusses results of the plutonium trifluoride two-stage precipitation study. A series of precipitation experiments was used to identify the significant process variables affecting precipitation performance. A mathematical model of the precipitation process was developed which is based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter which can be used to control the performance of the plutonium trifluoride precipitation process. Recommendations have been made which will optimize the FB-Line plutonium trifluoride precipitation process.

  10. An Improved Plutonium Trifluoride Precipitation Flowsheet

    International Nuclear Information System (INIS)

    Harmon, H.D.

    2001-01-01

    This report discusses results of the plutonium trifluoride two-stage precipitation study. A series of precipitation experiments was used to identify the significant process variables affecting precipitation performance. A mathematical model of the precipitation process was developed which is based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter which can be used to control the performance of the plutonium trifluoride precipitation process. Recommendations have been made which will optimize the FB-Line plutonium trifluoride precipitation process

  11. TCA precipitation.

    Science.gov (United States)

    Koontz, Laura

    2014-01-01

    Trichloroacetic acid (TCA) precipitation of proteins is commonly used to concentrate protein samples or remove contaminants, including salts and detergents, prior to downstream applications such as SDS-PAGE or 2D-gels. TCA precipitation denatures the protein, so it should not be used if the protein must remain in its folded state (e.g., if you want to measure a biochemical activity of the protein). © 2014 Elsevier Inc. All rights reserved.

  12. Chemical Alteration of Soils on Earth as a Function of Precipitation: Insights Into Weathering Processes Relevant to Mars

    Science.gov (United States)

    Amundson, R.; Chadwick, O.; Ewing, S.; Sutter, B.; Owen, J.; McKay, C.

    2004-12-01

    Soils lie at the interface of the atmosphere and lithosphere, and the rates of chemical and physical processes that form them hinge on the availability of water. Here we quantify the effect of these processes on soil volume and mass in different rainfall regimes. We then use the results of this synthesis to compare with the growing chemical dataset for soils on Mars in order to identify moisture regimes on Earth that may provide crude analogues for past Martian weathering conditions. In this synthesis, the rates of elemental gains/losses, and corresponding volumetric changes, were compared for soils in nine soil chronosequences (sequences of soils of differing ages) - sequences formed in climates ranging from ~1 to ~4500 mm mean annual precipitation (MAP). Total elemental chemistry of soils and parent materials were determined via XRF, ICP-MS, and/or ICP-OES, and the absolute elemental gains or losses (and volume changes) were determined by normalizing data to an immobile index element. For the chronosequences examined, the initial stages of soil formation (103^ to 104^ yr), regardless of climate, generally show volumetric expansion due to (1) reduction in bulk density by biological/physical turbation, (2) addition of organic matter, (3) accumulation of water during clay mineral synthesis, and/or (4) accumulation of atmospheric salts and dust. Despite large differences in parent materials (basalt, sandstone, granitic alluvium), there was a systematic relationship between long-term (105^ to 106^ yr) volumetric change and rainfall, with an approximate cross-over point between net expansion (and accumulation of atmospheric solutes and dust) and net collapse (net losses of Si, Al, and alkaline earths and alkali metals) between approximately 20 and 100 mm MAP. Recently published geochemical data of soils at Gusev Crater (Gellert et al. 2004. Science 305:829), when normalized to Ti, show apparent net losses of Si and Al that range between 5 and 50% of values relative to

  13. Microstructure, microtexture and precipitation in the ultrafine-grained surface layer of an Al-Zn-Mg-Cu alloy processed by sliding friction treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yanxia [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Yang, Yanqing, E-mail: yqyang@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Feng, Zongqiang [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Zhao, Guangming; Huang, Bin; Luo, Xian [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Zhang, Yusheng; Zhang, Wei [Northwest Institute for Nonferrous Metal Research, Xi' an 710016 (China)

    2017-01-15

    Precipitate redistribution and texture evolution are usually two concurrent aspects accompanying grain refinement induced by various surface treatment. However, the detailed precipitate redistribution characteristics and process, as well as crystallographic texture in the surface refined grain layer, are still far from full understanding. In this study, we focused on the microstructural and crystallographic features of the sliding friction treatment (SFT) induced surface deformation layer in a 7050 aluminum alloy. With the combination of transmission electron microscopy (TEM) and high angle angular dark field scanning TEM (HAADF-STEM) observations, a surface ultrafine grain (UFG) layer composed of both equiaxed and lamellar ultrafine grains and decorated by high density of coarse grain boundary precipitates (GBPs) were revealed. Further precession electron diffraction (PED) assisted orientation mapping unraveled that high angle grain boundaries rather than low angle grain boundaries are the most favorable nucleation sites for GBPs. The prominent precipitate redistribution can be divided into three successive and interrelated stages, i.e. the mechanically induced precipitate dissolution, solute diffusion and reprecipitation. The quantitative prediction based on pipe diffusion along dislocations and grain boundary diffusion proved the distribution feasibility of GBPs around UFGs. Based on PED and electron backscatter diffraction (EBSD) analyses, the crystallographic texture of the surface UFG layer was identified as a shear texture composed of major rotated cube texture (001) 〈110〉 and minor (111) 〈112〉, while that of the adjoining lamellar coarse grained matrix was pure brass. The SFT induced surface severe shear deformation is responsible for texture evolution. - Highlights: •The surface ultrafine grain layer in a 7050 aluminum alloy was focused. •Precipitate redistribution and texture evolution were discussed. •The quantitative prediction proved the

  14. Evolution of mechanical behavior of 6XXX aluminium alloy due to the precipitation state during a thermo-mechanical process

    International Nuclear Information System (INIS)

    Bardel, Didier; Perez, Michel; Nelias, Daniel; Chaise, Thibaut; Garnier, Jerome; Bourlier, Florent

    2014-01-01

    The aim of this research is to link the microstructural state and the mechanical properties of an age hardening alloy during a fast heat treatment such as encountered during welding. A coupled model between precipitation state and mechanical properties is used to predict the yield strength and hardening behavior that can be observed experimentally. The method permits the identification of the kinematic and isotropic contributions in the hardening model. The methodology is applied to a 6061-T6 aluminium alloy which is used in the Jules Horowitz reactor vessel. The general idea of this methodology is to couple an efficient microstructural model to a mechanical one based on the dislocation theory and ad'hoc experiments. The theoretical background is based on the work of Kampmann and Wagner, known as the KWN model, to account for nucleation, growth/dissolution and coarsening of precipitates. This analysis requires transient thermo-mechanical experimental data. The efficiency of these models and their coupling are shown for a series 6XXX aluminium alloy which contains β'' and β' precipitates. Ultimately these models are coupled to a FEA model and allows to predict the distribution of precipitates within each element of the mesh, and subsequently its mechanical behavior. (authors)

  15. Deformation induced dynamic recrystallization and precipitation strengthening in an Mg−Zn−Mn alloy processed by high strain rate rolling

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jimiao; Song, Min [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Yan, Hongge [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Yang, Chao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Ni, Song, E-mail: song.ni@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2016-11-15

    The microstructure of a high strain-rate rolled Mg−Zn−Mn alloy was investigated by transmission electron microscopy to understand the relationship between the microstructure and mechanical properties. The results indicate that: (1) a bimodal microstructure consisting of the fine dynamic recrystallized grains and the largely deformed grains was formed; (2) a large number of dynamic precipitates including plate-like MgZn{sub 2} phase, spherical MgZn{sub 2} phase and spherical Mn particles distribute uniformly in the grains; (3) the major facets of many plate-like MgZn{sub 2} precipitates deviated several to tens of degrees (3°–30°) from the matrix basal plane. It has been shown that the high strength of the alloy is attributed to the formation of the bimodal microstructure, dynamic precipitation, and the interaction between the dislocations and the dynamic precipitates. - Highlights: •A bimodal microstructure was formed in a high strain-rate rolled Mg−Zn−Mn alloy. •Plate-like MgZn{sub 2}, spherical MgZn{sub 2} and spherical Mn phases were observed. •The major facet of the plate-like MgZn{sub 2} deviated from the matrix basal plane.

  16. Combined observational and modeling efforts of aerosol-cloud-precipitation interactions over Southeast Asia

    Science.gov (United States)

    Loftus, Adrian; Tsay, Si-Chee; Nguyen, Xuan Anh

    2016-04-01

    Low-level stratocumulus (Sc) clouds cover more of the Earth's surface than any other cloud type rendering them critical for Earth's energy balance, primarily via reflection of solar radiation, as well as their role in the global hydrological cycle. Stratocumuli are particularly sensitive to changes in aerosol loading on both microphysical and macrophysical scales, yet the complex feedbacks involved in aerosol-cloud-precipitation interactions remain poorly understood. Moreover, research on these clouds has largely been confined to marine environments, with far fewer studies over land where major sources of anthropogenic aerosols exist. The aerosol burden over Southeast Asia (SEA) in boreal spring, attributed to biomass burning (BB), exhibits highly consistent spatiotemporal distribution patterns, with major variability due to changes in aerosol loading mediated by processes ranging from large-scale climate factors to diurnal meteorological events. Downwind from source regions, the transported BB aerosols often overlap with low-level Sc cloud decks associated with the development of the region's pre-monsoon system, providing a unique, natural laboratory for further exploring their complex micro- and macro-scale relationships. Compared to other locations worldwide, studies of springtime biomass-burning aerosols and the predominately Sc cloud systems over SEA and their ensuing interactions are underrepresented in scientific literature. Measurements of aerosol and cloud properties, whether ground-based or from satellites, generally lack information on microphysical processes; thus cloud-resolving models are often employed to simulate the underlying physical processes in aerosol-cloud-precipitation interactions. The Goddard Cumulus Ensemble (GCE) cloud model has recently been enhanced with a triple-moment (3M) bulk microphysics scheme as well as the Regional Atmospheric Modeling System (RAMS) version 6 aerosol module. Because the aerosol burden not only affects cloud

  17. The Impact of the Diurnal Cycle of Clouds and Precipitation over the Maritime Continent on the Propagation of the MJO into the Western Pacific

    Science.gov (United States)

    Burleyson, C. D.; Hagos, S. M.; Feng, Z.

    2016-12-01

    The processes that determine the interaction between the islands of the maritime continent (MC) and the eastward propagation of the Madden-Julian Oscillation (MJO) are poorly understood. We are undertaking a series of observational and modeling analyses aimed at understanding how clouds and precipitation over the islands of the MC lead to changes in the intensity of the MJO (inferred by the amplitude of the Real-time Multivariate MJO index [RMM] and other metrics) as it crosses the MC. One component of our analysis uses the long-term measurements from the DOE Atmospheric Radiation Measurement (ARM) sites in the Tropical Western Pacific (TWP) to examine cloud radiative effects as the MJO crosses the MC. Using the multi-year ARM dataset and a cloud resolving model (CRM), we show that the MJO interacts with the diurnal cycle of surface heating, clouds, and precipitation over the islands of the MC in a way that weakens it. Additionally, using a satellite climatology based on the TRMM 3B42 dataset we found that MJO episodes that weaken as they cross the MC are characterized by more frequent precipitation and warmer sea surface temperatures (SSTs) south of the equator and less frequent precipitation north of the equator compared to cases where the MJO intensifies. The north-south polarity in SSTs suggests a seasonal dependence in the ability of the MJO to cross the MC. This seasonality was confirmed by looking the seasonal distribution of changes in MJO amplitude as it crosses the MC. Consistent with the SST result, we found that MJO episodes that intensify as they cross the MC are more likely to occur during the northern hemisphere summer and less likely to occur during the northern hemisphere winter (Fig. 1). A regional CRM and satellite observations are used jointly to explore the processes responsible for this seasonality and to examine the impact of interannual oscillations such as ENSO and monsoons on the ability of the MJO to cross the MC. Fig. 1. The annual

  18. Precipitation Matters

    Science.gov (United States)

    McDuffie, Thomas

    2007-01-01

    Although weather, including its role in the water cycle, is included in most elementary science programs, any further examination of raindrops and snowflakes is rare. Together rain and snow make up most of the precipitation that replenishes Earth's life-sustaining fresh water supply. When viewed individually, raindrops and snowflakes are quite…

  19. Lithium recycling and cathode material regeneration from acid leach liquor of spent lithium-ion battery via facile co-extraction and co-precipitation processes.

    Science.gov (United States)

    Yang, Yue; Xu, Shengming; He, Yinghe

    2017-06-01

    A novel process for extracting transition metals, recovering lithium and regenerating cathode materials based on facile co-extraction and co-precipitation processes has been developed. 100% manganese, 99% cobalt and 85% nickel are co-extracted and separated from lithium by D2EHPA in kerosene. Then, Li is recovered from the raffinate as Li 2 CO 3 with the purity of 99.2% by precipitation method. Finally, organic load phase is stripped with 0.5M H 2 SO 4 , and the cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 is directly regenerated from stripping liquor without separating metal individually by co-precipitation method. The regenerative cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 is miro spherical morphology without any impurities, which can meet with LiNi 1/3 Co 1/3 Mn 1/3 O 2 production standard of China and exhibits good electrochemical performance. Moreover, a waste battery management model is introduced to guarantee the material supply for spent battery recycling. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Effects of Convective Aggregation on Radiative Cooling and Precipitation in a CRM

    Science.gov (United States)

    Naegele, A. C.; Randall, D. A.

    2017-12-01

    In the global energy budget, the atmospheric radiative cooling (ARC) is approximately balanced by latent heating, but on regional scales, the ARC and precipitation rates are inversely related. We use a cloud-resolving model to explore how the relationship between precipitation and the ARC is affected by convective aggregation, in which the convective activity is confined to a small portion of the domain that is surrounded by a much larger region of dry, subsiding air. Sensitivity tests show that the precipitation rate and ARC are highly sensitive to both SST and microphysics; a higher SST and 1-moment microphysics both act to increase the domain-averaged ARC and precipitation rates. In all simulations, both the domain-averaged ARC and precipitation rates increased due to convective aggregation, resulting in a positive temporal correlation. Furthermore, the radiative effect of clouds in these simulations is to decrease the ARC. This finding is consistent with our observational results of the cloud effect on the ARC, and has implications for convective aggregation and the geographic extent in which it can occur.

  1. Use of linear regression for the processing of curves of differential potentiometric titration of a binary mixture of heterovalent ions using precipitation reactions

    International Nuclear Information System (INIS)

    Mar'yanov, B.M.; Zarubin, A.G.; Shumar, S.V.

    2003-01-01

    A method is proposed for the computer processing of curve of differential potentiometric titration of a binary mixture of heterovalent ions using precipitation reactions. The method is based on the transformation of the titration curve to segment-line characteristics, whose parameters (within the accuracy of the least-squares method) determine the sequence of the equivalence points and solubility products of the resulting precipitation. The method is applied to the titration of Ag(I)-Cd)II), Hg(II)-Te(IV), and Cd(II)-Te(IV) mixtures by a sodium diethyldithiocarbamate solution with membrane sulfide and glassy carbon indicator electrodes. For 4 to 11 mg of the analyte in 50 ml of the solution, RSD varies from 1 to 9% [ru

  2. Influence of Microstructure and Process Conditions on Simultaneous Low-Temperature Surface Hardening and Bulk Precipitation Hardening of Nanoflex®

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas L.

    2015-01-01

    Precipitation hardening martensitic stainless steel Nanoflex was low-temperature nitrided or nitrocarburized. In these treatments, simultaneous hardening of the bulk, by precipitation hardening, and the surface by dissolving nitrogen/carbon can be obtained because the treatment temperatures...... and times for these essentially different hardening mechanisms are compatible. The effect of the processing history of the steel on the nitrided/nitrocarburized case was investigated by varying the amounts of austenite and martensite through variation of the degree of plastic deformation by tensile strain...... consisting of martensite results in the deepest nitrided case, while a shallow case develops on a microstructure consisting of austenite. For an initial microstructure consisting of both martensite and austenite a non-uniform case depth is achieved. Simultaneous bulk and surface hardening is only possible...

  3. Assessment of WRF microphysics schemes to simulate extreme precipitation events from the perspective of GMI radiative signatures

    Science.gov (United States)

    Choi, Y.; Shin, D. B.; Joh, M.

    2015-12-01

    Numerical simulations of precipitation depend to a large degree on the assumed cloud microphysics schemes representing the formation, growth and fallout of cloud droplets and ice crystals. Recent studies show that assumed cloud microphysics play a major role not only in forecasting precipitation, especially in cases of extreme precipitation events, but also in the quality of the passive microwave rainfall estimation. Evaluations of the various Weather Research Forecasting (WRF) model microphysics schemes in this study are based on a method that was originally developed to construct the a-priori databases of precipitation profiles and associated brightness temperatures (TBs) for precipitation retrievals. This methodology generates three-dimensional (3D) precipitation fields by matching the GPM dual frequency radar (DPR) reflectivity profiles with those calculated from cloud resolving model (CRM)-derived hydrometeor profiles. The method eventually provides 3D simulated precipitation fields over the DPR scan swaths. That is, atmospheric and hydrometeor profiles can be generated at each DPR pixel based on CRM and DPR reflectivity profiles. The generated raining systems over DPR observation fields can be applied to any radiometers that are unaccompanied with a radar for microwave radiative calculation with consideration of each sensor's channel and field of view. Assessment of the WRF model microphysics schemes for several typhoon cases in terms of emission and scattering signals of GMI will be discussed.

  4. DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

    Science.gov (United States)

    Fries, B.A.

    1959-11-10

    A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

  5. Study of UO2-10WT%Gd2O3 fuel pellets obtained by seeding method using AUC co-precipitation and mechanical mixing processes

    International Nuclear Information System (INIS)

    Lima, M.M.F.; Ferraz, W.B.A.; Santos, M.M. dos; Pinto, L.C.M.; Santos, A.

    2008-01-01

    The use of gadolinium and uranium mixed oxide as a nuclear fuel aims to obtain a fuel with a performance better than that of UO 2 fuel. In this work, seeding method was used to improve ionic diffusivity during sintering to produce high density pellets containing coarse grains by co-precipitation and mechanical mixing processes. Sintered UO 2 -10 wt% Gd 2 O 3 pellets were obtained using the reference processes with 2 wt% and 5 wt% UO 2 seeds with two granulometries, less than 20 μm and between 20 and 38 μm. Characterisation was carried out by chemical analysis, surface area, X-ray diffraction, SEM, WDS, image analysis, and densitometry. The seeding method using mechanical mixing process was more effective than the co-precipitation method. Furthermore, mechanical mixing process resulted in an increase in density of UO 2 -10wt% Gd 2 O 3 with seeds in relation to that of UO 2 -10wt% Gd 2 O 3 without seeds. (author)

  6. Near-Infrared Spectroscopy as an Analytical Process Technology for the On-Line Quantification of Water Precipitation Processes during Danhong Injection

    Directory of Open Access Journals (Sweden)

    Xuesong Liu

    2015-01-01

    Full Text Available This paper used near-infrared (NIR spectroscopy for the on-line quantitative monitoring of water precipitation during Danhong injection. For these NIR measurements, two fiber optic probes designed to transmit NIR radiation through a 2 mm flow cell were used to collect spectra in real-time. Partial least squares regression (PLSR was developed as the preferred chemometrics quantitative analysis of the critical intermediate qualities: the danshensu (DSS, (R-3, 4-dihydroxyphenyllactic acid, protocatechuic aldehyde (PA, rosmarinic acid (RA, and salvianolic acid B (SAB concentrations. Optimized PLSR models were successfully built and used for on-line detecting of the concentrations of DSS, PA, RA, and SAB of water precipitation during Danhong injection. Besides, the information of DSS, PA, RA, and SAB concentrations would be instantly fed back to site technical personnel for control and adjustment timely. The verification experiments determined that the predicted values agreed with the actual homologic value.

  7. Near-Infrared Spectroscopy as an Analytical Process Technology for the On-Line Quantification of Water Precipitation Processes during Danhong Injection.

    Science.gov (United States)

    Liu, Xuesong; Wu, Chunyan; Geng, Shu; Jin, Ye; Luan, Lianjun; Chen, Yong; Wu, Yongjiang

    2015-01-01

    This paper used near-infrared (NIR) spectroscopy for the on-line quantitative monitoring of water precipitation during Danhong injection. For these NIR measurements, two fiber optic probes designed to transmit NIR radiation through a 2 mm flow cell were used to collect spectra in real-time. Partial least squares regression (PLSR) was developed as the preferred chemometrics quantitative analysis of the critical intermediate qualities: the danshensu (DSS, (R)-3, 4-dihydroxyphenyllactic acid), protocatechuic aldehyde (PA), rosmarinic acid (RA), and salvianolic acid B (SAB) concentrations. Optimized PLSR models were successfully built and used for on-line detecting of the concentrations of DSS, PA, RA, and SAB of water precipitation during Danhong injection. Besides, the information of DSS, PA, RA, and SAB concentrations would be instantly fed back to site technical personnel for control and adjustment timely. The verification experiments determined that the predicted values agreed with the actual homologic value.

  8. Two-stage precipitation of neptunium (IV) oxalate

    International Nuclear Information System (INIS)

    Luerkens, D.W.

    1983-07-01

    Neptunium (IV) oxalate was precipitated using a two-stage precipitation system. A series of precipitation experiments was used to identify the significant process variables affecting precipitate characteristics. Process variables tested were input concentrations, solubility conditions in the first stage precipitator, precipitation temperatures, and residence time in the first stage precipitator. A procedure has been demonstrated that produces neptunium (IV) oxalate particles that filter well and readily calcine to the oxide

  9. Centrifugal precipitation chromatography

    Science.gov (United States)

    Ito, Yoichiro; Lin, Qi

    2009-01-01

    Centrifugal precipitation chromatography separates analytes according their solubility in ammonium sulfate (AS) solution and other precipitants. The separation column is made from a pair of long spiral channels partitioned with a semipermeable membrane. In a typical separation, concentrated ammonium sulfate is eluted through one channel while water is eluted through the other channel in the opposite direction. The countercurrent process forms an exponential AS concentration gradient through the water channel. Consequently, protein samples injected into the water channel is subjected to a steadily increasing AS concentration and at the critical AS concentration they are precipitated and deposited in the channel bed by the centrifugal force. Then the chromatographic separation is started by gradually reducing the AS concentration in the AS channel which lowers the AS gradient concentration in the water channel. This results in dissolution of deposited proteins which are again precipitated at an advanced critical point as they move through the channel. Consequently, proteins repeat precipitation and dissolution through a long channel and finally eluted out from the column in the order of their solubility in the AS solution. The present method has been successfully applied to a number of analytes including human serum proteins, recombinant ketosteroid isomerase, carotenoid cleavage enzymes, plasmid DNA, polysaccharide, polymerized pigments, PEG-protein conjugates, etc. The method is capable to single out the target species of proteins by affinity ligand or immunoaffinity separation. PMID:19541553

  10. Microbial network of the carbonate precipitation process induced by microbial consortia and the potential application to crack healing in concrete.

    Science.gov (United States)

    Zhang, Jiaguang; Zhou, Aijuan; Liu, Yuanzhen; Zhao, Bowei; Luan, Yunbo; Wang, Sufang; Yue, Xiuping; Li, Zhu

    2017-11-06

    Current studies have employed various pure-cultures for improving concrete durability based on microbially induced carbonate precipitation (MICP). However, there have been very few reports concerned with microbial consortia, which could perform more complex tasks and be more robust in their resistance to environmental fluctuations. In this study, we constructed three microbial consortia that are capable of MICP under aerobic (AE), anaerobic (AN) and facultative anaerobic (FA) conditions. The results showed that AE consortia showed more positive effects on inorganic carbon conversion than AN and FA consortia. Pyrosequencing analysis showed that clear distinctions appeared in the community structure between different microbial consortia systems. Further investigation on microbial community networks revealed that the species in the three microbial consortia built thorough energetic and metabolic interaction networks regarding MICP, nitrate-reduction, bacterial endospores and fermentation communities. Crack-healing experiments showed that the selected cracks of the three consortia-based concrete specimens were almost completely healed in 28 days, which was consistent with the studies using pure cultures. Although the economic advantage might not be clear yet, this study highlights the potential implementation of microbial consortia on crack healing in concrete.

  11. Electrical operation of electrostatic precipitators

    CERN Document Server

    Parker, Ken

    2003-01-01

    The electrostatic precipitator remains on of the most cost effective means of controlling the emission of particulates from most industrial processes. This book will be of interest to both users and suppliers of electrostatic precipitators as well as advanced students on environmental based courses. The author identifies the physical and engineering basis for the development of electrical equipment for electrostatic precipitators and thoroughly explores the technological factors which optimize the efficiency of the precipitator and hence minimize emissions, as well as future developments in th

  12. Final Technical Report for "High-resolution global modeling of the effects of subgrid-scale clouds and turbulence on precipitating cloud systems"

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Vincent [Univ. of Wisconsin, Milwaukee, WI (United States)

    2016-11-25

    The Multiscale Modeling Framework (MMF) embeds a cloud-resolving model in each grid column of a General Circulation Model (GCM). A MMF model does not need to use a deep convective parameterization, and thereby dispenses with the uncertainties in such parameterizations. However, MMF models grossly under-resolve shallow boundary-layer clouds, and hence those clouds may still benefit from parameterization. In this grant, we successfully created a climate model that embeds a cloud parameterization (“CLUBB”) within a MMF model. This involved interfacing CLUBB’s clouds with microphysics and reducing computational cost. We have evaluated the resulting simulated clouds and precipitation with satellite observations. The chief benefit of the project is to provide a MMF model that has an improved representation of clouds and that provides improved simulations of precipitation.

  13. Study and modeling of the dispersed phase behavior in a pulsed column: application to an oxalic precipitation process

    International Nuclear Information System (INIS)

    Amokrane, Abdenour

    2014-01-01

    The thesis focuses on the study and modeling of a pulsed column used in liquid-liquid extraction operations in the nuclear industry and which is otherwise considered for continuous precipitation operations in emulsion. Modeling the behavior of the dispersed phase in the column is undertaken in this manuscript. First, we began by modeling the continuous phase mean velocity and turbulence fields, which are responsible for transport, breakage and coalescence of the drops. The model developed, validated by PIV measurements, predicts turbulence in a satisfying way. Modeling the residence time distribution (RTD) of the drops by a Lagrangian approach is then achieved. This model is validated on measurements taken by a shadow-graph technique. The simulation results are in good agreement with the experimental ones. To model the droplet size distributions (DSD) in the column, we used the population balance equations (PBE) that we have coupled with the computational fluid dynamics equations (CFD). A continuously stirred tank reactor (CSTR) with an optical sensor is used, at first, to acquire the DSD representative of our liquid-liquid system. Through a 0D modeling of the flow in the CSTR, and solving the inverse problem, we have determined the breakage and coalescence kernels relevant for our system, to be used in the PBE. These kernels were then used to predict the DSD in the pulsed column by a coupled CFD-PBE model based on the QMOM method. Finally, a validation of the coupled CFD-PBE model is made from DSD in good agreement with the experimental data both qualitatively and quantitatively. The validated model is then used to study the emulsion sensitivity to the column operating conditions. (author) [fr

  14. CONCENTRATION OF Pu USING AN IODATE PRECIPITATE

    Science.gov (United States)

    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.

  15. Bulk and thick films of the superconducting phase YBa2Cu3O7/sub -//sub y/ made by controlled precipitation and sol-gel processes

    International Nuclear Information System (INIS)

    Barboux, P.; Tarascon, J.M.; Greene, L.H.; Hull, G.W.; Bagley, B.G.

    1988-01-01

    The synthesis of high-temperature superconducting oxides using solution chemistry has been investigated and physical properties are compared to ceramics obtained by conventional solid-state reactions. We report on controlled precipitation and sol-gel processes, both of which produce materials with particle sizes smaller than 5 μm. We find that the superconducting properties of the high T/sub c/ ceramics are affected by their manner of preparation, such that the transitions are slightly lower in temperature, but sharper, for samples made by solution rather than solid-state chemistry. The ability to prepare stable viscous gels provides an opportunity for obtaining large areas of superconducting coatings. For thick films on alumina or silicon substrates, contamination from the substrate is shown to be a problem. Finally, we observe that the sol-gel process lowers the synthesis temperature by 100 0 C.ing,

  16. Wastewater parameters after the process of phosphorus compounds removal by the metal dissolution method in comparison with precipitation and electrocoagulation methods

    Directory of Open Access Journals (Sweden)

    Wysocka Izabela

    2017-03-01

    Full Text Available Precipitation methods are commonly used for removing phosphorus compounds from wastewater. Chemical precipitation method, based on adding iron, aluminium or calcium salts to the treated wastewater, is often used. Another possible way of precipitating phosphates is metal dissolution method, which is presented in this paper. The main difference between these two methods is how the phosphate precipitating ions are introduced to the wastewater.

  17. Near infrared spectroscopy combined with multivariate analysis for monitoring the ethanol precipitation process of fraction I + II + III supernatant in human albumin separation

    Science.gov (United States)

    Li, Can; Wang, Fei; Zang, Lixuan; Zang, Hengchang; Alcalà, Manel; Nie, Lei; Wang, Mingyu; Li, Lian

    2017-03-01

    Nowadays, as a powerful process analytical tool, near infrared spectroscopy (NIRS) has been widely applied in process monitoring. In present work, NIRS combined with multivariate analysis was used to monitor the ethanol precipitation process of fraction I + II + III (FI + II + III) supernatant in human albumin (HA) separation to achieve qualitative and quantitative monitoring at the same time and assure the product's quality. First, a qualitative model was established by using principal component analysis (PCA) with 6 of 8 normal batches samples, and evaluated by the remaining 2 normal batches and 3 abnormal batches. The results showed that the first principal component (PC1) score chart could be successfully used for fault detection and diagnosis. Then, two quantitative models were built with 6 of 8 normal batches to determine the content of the total protein (TP) and HA separately by using partial least squares regression (PLS-R) strategy, and the models were validated by 2 remaining normal batches. The determination coefficient of validation (Rp2), root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and ratio of performance deviation (RPD) were 0.975, 0.501 g/L, 0.465 g/L and 5.57 for TP, and 0.969, 0.530 g/L, 0.341 g/L and 5.47 for HA, respectively. The results showed that the established models could give a rapid and accurate measurement of the content of TP and HA. The results of this study indicated that NIRS is an effective tool and could be successfully used for qualitative and quantitative monitoring the ethanol precipitation process of FI + II + III supernatant simultaneously. This research has significant reference value for assuring the quality and improving the recovery ratio of HA in industrialization scale by using NIRS.

  18. A three-prong strategy to develop functional food using protein isolates recovered from chicken processing by-products with isoelectric solubilization/precipitation.

    Science.gov (United States)

    Tahergorabi, Reza; Sivanandan, Litha; Beamer, Sarah K; Matak, Kristen E; Jaczynski, Jacek

    2012-09-01

    Skin-on bone-in chicken drumsticks were processed with isoelectric solubilization/precipitation to recover muscle proteins. The drumsticks were used as a model for dark chicken meat processing by-products. The main objective of this study was conversion of dark chicken meat processing by-products to restructured functional food product. An attempt was made to develop functional food product that would resemble respective product made from boneless skinless chicken breast meat. A three-prong strategy to address diet-driven cardiovascular disease (CVD)with a functional food was used in this study. The strategy included addition of three ingredients with well-documented cardiovascular benefits: (i) ω-3 polyunsaturated fatty acid-rich oil (flaxseed-algae, 9:1); (ii) soluble fiber; and (iii) salt substitute. Titanium dioxide, potato starch, polyphosphate, and transglutaminase were also added. The batters were formulated and cooked resulting in heat-set gels. Color (L*a*b*), texture (torsion test, Kramer shear test, and texture profile analysis), thermal denaturation (differential scanning calorimetry), and gelation (dynamic rheology) of chicken drumstick gels and chicken breast gels were determined and compared. Chicken drumstick gels generally had comparable color and texture properties to the gels made from chicken breast meat. The endothermic transition (thermal denaturation) of myosin was more pronounced and gelation properties were better for the drumstick gels. This study demonstrated a feasibility to develop functional food made of muscle proteins recovered with isoelectric solubilization/precipitation from low-value dark chicken meat processing by-products. The functional food developed in this study was enriched with CVD-beneficial nutrients and had comparable instrumental quality attributes to respective products made of chicken breast meat. Although the results of this study point towards the potential for a novel, marketable functional food product, sensory

  19. Near infrared spectroscopy combined with multivariate analysis for monitoring the ethanol precipitation process of fraction I+II+III supernatant in human albumin separation.

    Science.gov (United States)

    Li, Can; Wang, Fei; Zang, Lixuan; Zang, Hengchang; Alcalà, Manel; Nie, Lei; Wang, Mingyu; Li, Lian

    2017-03-15

    Nowadays, as a powerful process analytical tool, near infrared spectroscopy (NIRS) has been widely applied in process monitoring. In present work, NIRS combined with multivariate analysis was used to monitor the ethanol precipitation process of fraction I+II+III (FI+II+III) supernatant in human albumin (HA) separation to achieve qualitative and quantitative monitoring at the same time and assure the product's quality. First, a qualitative model was established by using principal component analysis (PCA) with 6 of 8 normal batches samples, and evaluated by the remaining 2 normal batches and 3 abnormal batches. The results showed that the first principal component (PC1) score chart could be successfully used for fault detection and diagnosis. Then, two quantitative models were built with 6 of 8 normal batches to determine the content of the total protein (TP) and HA separately by using partial least squares regression (PLS-R) strategy, and the models were validated by 2 remaining normal batches. The determination coefficient of validation (R p 2 ), root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and ratio of performance deviation (RPD) were 0.975, 0.501g/L, 0.465g/L and 5.57 for TP, and 0.969, 0.530g/L, 0.341g/L and 5.47 for HA, respectively. The results showed that the established models could give a rapid and accurate measurement of the content of TP and HA. The results of this study indicated that NIRS is an effective tool and could be successfully used for qualitative and quantitative monitoring the ethanol precipitation process of FI+II+III supernatant simultaneously. This research has significant reference value for assuring the quality and improving the recovery ratio of HA in industrialization scale by using NIRS. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Precipitation phases at different processes and heat treat ments as well as their effects on the mechanical properties of super-austenitic stainless steel

    Science.gov (United States)

    Sun, Hunying; Zhou, Zhangjian; Wang, Man; Li, Shaofu; Zhang, Liwei; Zou, Lei

    2013-03-01

    A new type lCr30Ni30Mo2TiZr super-austenitic stainless steel has been developed. The microstructures, precipitation phases and mechanical properties of the steel under different deformation processes and heat treatment (solution, stabilized treatment) were investigated using X-ray Diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) as well as mechanical tests. The results indicate that coarse carbides such as Cr-rich M23C6, sigma (σ), and little chi (χ) phases were formed in the steel, and large α' -Cr phases were also detected at three joint grain boundaries, and they were promoted by large strain. The precipitate phases were dissolved or transformed to intermetallic phase even at higher elevated temperature, and influenced the mechanical property obviously. These intermetallic compounds seriously reduced elongation of the rolled steel at room temperature and 700 °C, but increased the forged one at 700 °C. Impact absorbed energies of the stabilized specimens were lower than half of that solution status.

  1. Reliable solution processed planar perovskite hybrid solar cells with large-area uniformity by chloroform soaking and spin rinsing induced surface precipitation

    Directory of Open Access Journals (Sweden)

    Yann-Cherng Chern

    2015-08-01

    Full Text Available A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells.

  2. A hybrid liquid-phase precipitation (LPP) process in conjunction with membrane distillation (MD) for the treatment of the INEEL sodium-bearing liquid waste.

    Science.gov (United States)

    Bader, M S H

    2005-05-20

    A novel hybrid system combining liquid-phase precipitation (LPP) and membrane distillation (MD) is integrated for the treatment of the INEEL sodium-bearing liquid waste. The integrated system provides a "full separation" approach that consists of three main processing stages. The first stage is focused on the separation and recovery of nitric acid from the bulk of the waste stream using vacuum membrane distillation (VMD). In the second stage, polyvalent cations (mainly TRU elements and their fission products except cesium along with aluminum and other toxic metals) are separated from the bulk of monovalent anions and cations (dominantly sodium nitrate) by a front-end LPP. In the third stage, MD is used first to concentrate sodium nitrate to near saturation followed by a rear-end LPP to precipitate and separate sodium nitrate along with the remaining minor species from the bulk of the aqueous phase. The LPP-MD hybrid system uses a small amount of an additive and energy to carry out the treatment, addresses multiple critical species, extracts an economic value from some of waste species, generates minimal waste with suitable disposal paths, and offers rapid deployment. As such, the LPP-MD could be a valuable tool for multiple needs across the DOE complex where no effective or economic alternatives are available.

  3. Synthesis of high-purity precipitated calcium carbonate during the process of recovery of elemental sulphur from gypsum waste

    CSIR Research Space (South Africa)

    De Beer, Morris

    2015-08-01

    Full Text Available (PCC). The process used an acid gas (H2S) to improve the aqueous dissolution of CaS, which is otherwise poorly soluble. The carbonate product was primarily calcite (99.5%) with traces of quartz (0.5%). Calcite was the only CaCO3 polymorph obtained...

  4. Effective Assimilation of Global Precipitation

    Science.gov (United States)

    Lien, G.; Kalnay, E.; Miyoshi, T.; Huffman, G. J.

    2012-12-01

    Assimilating precipitation observations by modifying the moisture and sometimes temperature profiles has been shown successful in forcing the model precipitation to be close to the observed precipitation, but only while the assimilation is taking place. After the forecast start, the model tends to "forget" the assimilation changes and lose their extra skill after few forecast hours. This suggests that this approach is not an efficient way to modify the potential vorticity field, since this is the variable that the model would remember. In this study, the ensemble Kalman filter (EnKF) method is used to effectively change the potential vorticity field by allowing ensemble members with better precipitation to receive higher weights. In addition to using an EnKF, two other changes in the precipitation assimilation process are proposed to solve the problems related to the highly non-Gaussian nature of the precipitation variable: a) transform precipitation into a Gaussian distribution based on its climatological distribution, and b) only assimilate precipitation at the location where some ensemble members have positive precipitation. The idea is first tested by the observing system simulation experiments (OSSEs) using SPEEDY, a simplified but realistic general circulation model. When the global precipitation is assimilated in addition to conventional rawinsonde observations, both the analyses and the medium range forecasts are significantly improved as compared to only having rawinsonde observations. The improvement is much reduced when only modifying the moisture field with the same approach, which shows the importance of the error covariance between precipitation and all other model variables. The effect of precipitation assimilation is larger in the Southern Hemisphere than that in the Northern Hemisphere because the Northern Hemisphere analyses are already accurate as a result of denser rawinsonde stations. Assimilation of precipitation using a more comprehensive

  5. The effects of microalloying with Cd on precipitation processes in Al-1.7 Cu-0.3 mg (At. %) alloys

    International Nuclear Information System (INIS)

    Sofyan, Bondan T.

    2002-01-01

    The present work investigates the effects of microalloying with Cd on precipitation processes in Al-1.7 Cu-0.3 mg (At. %) alloys. Analytical STEM (Scanning Transmission Electron Microscope) revealed the presence of clusters rich in Cd and Mg at early stages of ageing, which is believed to be responsible in promoting the nucleation of θ (Al,Cu) in the alloy on its (001) planes. The Cd-Mg clusters then grow as Cd-Mg-rich particles when ageing is continued beyond the peak hardness. The presence of Cd-Mg-rich clusters is thought to play an important role on the nucleation of θ phase by accommodating the misfit strain on the non-coherent rim of the phase. The accommodation of misfit strain is made available by the presence of large amount of vacancies, which is trapped by Cd and Mg atoms during quenching, around θ platelet nuclei

  6. Low-temperature synthesis of CuFeO{sub 2} (delafossite) at 70 °C: A new process solely by precipitation and ageing

    Energy Technology Data Exchange (ETDEWEB)

    John, Melanie, E-mail: melanie.john@min.uni-muenchen.de [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Heuss-Aßbichler, Soraya [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Park, So-Hyun [Section Crystallography, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Ullrich, Aladin [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany); Benka, Georg [Physics Department, Technical University Munich, James-Franck-Straße 1, 85748 Garching (Germany); Petersen, Nikolai [Section Geophysics, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Rettenwander, Daniel [Department of Materials Research & Physics, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Horn, Siegfried R. [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany)

    2016-01-15

    This study presents a new low temperature synthesis method to obtain pure delafossite (Cu{sup 1+}Fe{sup 3+}O{sub 2}) at a temperature of 70 °C within 24 h. For the first time delafossite is synthesized solely by precipitation and subsequent ageing process and without usage of any additives controlling the oxidation state of copper. The synthesized material, called LT-delafossite, consists of pure Cu{sup 1+}Fe{sup 3+}O{sub 2} exclusive of any side products. Rietveld analysis confirms the presence of both 3R (space group (SG): R-3m) and 2H (SG: P6{sub 3}/mmc) polytypes in LT-delafossite. Electron microscopy images show nanometer-sized hexagonal plates with a diameter <500 nm and a thickness of <30 nm. Measurements of the magnetic susceptibility from 2 K to 350 K in zero-field show one peak ∼18.5 K, which is attributed to an AFM phase transition. Zero-field-cooled magnetization data between −14 T and +14 T at 2 K revealed an s-shape form around the origin having no remanent magnetization. - Highlights: • New process: low temperature synthesis of pure CuFeO{sub 2} nanoparticles. • Synthesis at 70 °C within 24 h solely by precipitation and ageing. • Nanoparticle characterization by XRD, FTIR, SEM, ICP–OES, TEM and Mößbauer. • Special magnetic properties of nano-sized CuFeO{sub 2} synthesized at low temperatures.

  7. Magnetite precipitation and characterisation

    International Nuclear Information System (INIS)

    Joyce, A.; Garside, J.; Ivens, R.

    1988-06-01

    Magnetite (Fe 3 O 4 ) precipitation was investigated as a possible alternative treatment process to the conventional ferric hydroxide for removal of actinides from radioactive effluents. This offered the possibility of improved dewatering of filtered residues. Whilst a poor quality magnetite could be produced from deoxygenated ferrous/ferric solutions, all attempts to prepare magnetite from effluent simulates were unsuccessful. The failure was attributed to the presence of high nitrate and other interfering ions. (author)

  8. Numerical Simulations of Precipitation Processes, Microphysics, and Microwave Radiative Properties of flood Producing Storms in Mediterranean & Adriatic Basins

    Science.gov (United States)

    Smith, Eric A.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    A comprehensive understanding of the meteorological and microphysical nature of Mediterranean storms requires a combination of in situ data analysis, radar data analysis, and satellite data analysis, effectively integrated with numerical modeling studies at various scales. An important aspect of understanding microphysical controls of severe storms, is first understanding the meteorological controls under which a storm has evolved, and then using that information to help characterize the dominant microphysical processes. For hazardous Mediterranean storms, highlighted by the October 5-6, 1998 Friuli flood event in northern Italy, a comprehensive microphysical interpretation requires an understanding of the multiple phases of storm evolution. This involves intense convective development, Sratiform decay, orographic lifting, and sloped frontal lifting processes, as well as the associated vertical motions and thermodynamical instabilities governing physical processes that effect details of the size distributions and fall rates of the various types of hydrometeors found within the storm environment. This talk overviews the microphysical elements of a severe Mediterranean storm in such a context, investigated with the aid of TRMM satellite and other remote sensing measurements, but guided by a nonhydrostatic mesoscale model simulation of the Friuli flood event. The data analysis for this paper was conducted by my research groups at the Global Hydrology and Climate Center in Huntsville, AL and Florida State University in Tallahassee, and in collaboration with Dr. Alberto Mugnai's research group at the Institute of Atmospheric Physics in Rome. The numerical modeling was conducted by Professor Oreg Tripoli and Ms. Giulia Panegrossi at the University of Wisconsin in Madison, using Professor Tripoli's nonhydrostatic modeling system (NMS). This is a scalable, fully nested mesoscale model capable of resolving nonhydrostatic circulations from regional scale down to cloud scale

  9. Encoding information into precipitation structures

    International Nuclear Information System (INIS)

    Martens, Kirsten; Bena, Ioana; Droz, Michel; Rácz, Zoltan

    2008-01-01

    Material design at submicron scales would be profoundly affected if the formation of precipitation patterns could be easily controlled. It would allow the direct building of bulk structures, in contrast to traditional techniques which consist of removing material in order to create patterns. Here, we discuss an extension of our recent proposal of using electrical currents to control precipitation bands which emerge in the wake of reaction fronts in A + + B – → C reaction–diffusion processes. Our main result, based on simulating the reaction–diffusion–precipitation equations, is that the dynamics of the charged agents can be guided by an appropriately designed time-dependent electric current so that, in addition to the control of the band spacing, the width of the precipitation bands can also be tuned. This makes straightforward the encoding of information into precipitation patterns and, as an amusing example, we demonstrate the feasibility by showing how to encode a musical rhythm

  10. Effects of alloying and processing modifications on precipitation and strength in 9%Cr ferritic/martensitic steels for fast reactor cladding

    Science.gov (United States)

    Tippey, Kristin E.

    P92 was modified with respect to alloying and processing in the attempt to enhance high-temperature microstructural stability and mechanical properties. Alloying effects were modeled in ThermoCalcRTM and analyzed with reference to literature. ThermoCalcRTM modeling was conducted to design two low-carbon P92-like low-carbon alloys with austenite stabilized by alternative alloying; full conversion to austenite allows for a fully martensitic structure. Goals included avoidance of Z-phase, decrease of M23C6 phase fraction and maintained or increased MX phase fraction. Fine carbonitride precipitation was optimized by selecting alloying compositions such that all V and Nb could be solutionized at temperatures outside the delta-ferrite phase field. A low-carbon alloy (LC) and a low-carbon-zero-niobium alloy (0Nb) were identified and fabricated. This low-carbon approach stems from the increased creep resistance reported in several low-carbon alloys, presumably from reduced M23C6 precipitation and maintained MX precipitation [1], although these low-carbon alloys also contained additional tungsten (W) and cobalt (Co) compared to the base P92 alloy. The synergistic effect of Co and W on the microstructure and mechanical properties are difficult to deconvolute. Higher solutionizing temperatures allow more V and Nb into solution and increase prior austenite grain size; however, at sufficiently high temperatures delta-ferrite forms. Optimal solutionizing temperatures to maximize V and Nb in solution, while avoiding the onset of the delta ferrite phase field, were analyzed in ThermoCalcRTM. Optical microscopy showed ThermoCalc RTM predicted higher delta-ferrite onset temperatures of 20 °C in P92 alloys to nearly 50 °C in the designed alloys of the critical temperature. Identifying the balance where maximum fine precipitation is achieved and delta-ferrite avoided is a key factor in the design of an acceptable P92-like alloy for Generation IV reactor cladding. Processing was

  11. Precipitation Sedimentation and Advection in GFS

    Science.gov (United States)

    Sun, R.; Tallapragada, V.

    2016-12-01

    Zhao and Carr microphysics scheme as implemented in the NCEP Global Forecasting System (GFS) predicts only the total cloud condensate (cloud water or ice). The precipitation generated in the column fall to the ground instantly. This mean precipitation sedimentation and advection are not considered. As resolution increases the lack of the two physical processes creates problems. The slowly falling precipitation (snow) falls to the wrong surface grid box, which may have led to the observed spotty-precipitation pattern. To solve the problem two prognositic variables, snow and rain, are added. Addition of the two precipitation variable allows their advection. The corresponding sedimentation process are also added. In this study we examine the effect of precipitation advection and sedimentation on the precipitation pattern, associated precipitation skills and clouds.

  12. Reproducibility of Carbon and Water Cycle by an Ecosystem Process Based Model Using a Weather Generator and Effect of Temporal Concentration of Precipitation on Model Outputs

    Science.gov (United States)

    Miyauchi, T.; Machimura, T.

    2014-12-01

    GCM is generally used to produce input weather data for the simulation of carbon and water cycle by ecosystem process based models under climate change however its temporal resolution is sometimes incompatible to requirement. A weather generator (WG) is used for temporal downscaling of input weather data for models, where the effect of WG algorithms on reproducibility of ecosystem model outputs must be assessed. In this study simulated carbon and water cycle by Biome-BGC model using weather data measured and generated by CLIMGEN weather generator were compared. The measured weather data (daily precipitation, maximum, minimum air temperature) at a few sites for 30 years was collected from NNDC Online weather data. The generated weather data was produced by CLIMGEN parameterized using the measured weather data. NPP, heterotrophic respiration (HR), NEE and water outflow were simulated by Biome-BGC using measured and generated weather data. In the case of deciduous broad leaf forest in Lushi, Henan Province, China, 30 years average monthly NPP by WG was 10% larger than that by measured weather in the growing season. HR by WG was larger than that by measured weather in all months by 15% in average. NEE by WG was more negative in winter and was close to that by measured weather in summer. These differences in carbon cycle were because the soil water content by WG was larger than that by measured weather. The difference between monthly water outflow by WG and by measured weather was large and variable, and annual outflow by WG was 50% of that by measured weather. The inconsistency in carbon and water cycle by WG and measured weather was suggested be affected by the difference in temporal concentration of precipitation, which was assessed.

  13. Precipitation of uranium concentrates by hydrogen peroxide

    International Nuclear Information System (INIS)

    Barbosa Filho, O.; Teixeira, L.A.C.

    1987-01-01

    An experimental study on the precipitation of uranyl peroxide (UO 4 x H 2 O) has been carried out in a laboratory scale. The objective was to assess the possibility of the peroxide route as an alternative to a conventional ammonium diuranate process. A factorial design was used to evaluate the effects of the initial pH, precipitation pH and H 2 O 2 /UO 2 2+ ratio upon the process. The responses were measured in terms of: efficiency of U precipitation, content of U in the precipitates, and distribution of impurities in the precipitates. (Author) [pt

  14. Effects of bacterially produced precipitates on the metabolism of sulfate reducing bacteria during the bio-treatment process of copper-containing wastewater

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A large volume of bacterially produced precipitates are generated during the bio-treatment of heavy metal wastewater.The composition of the bacterially produced precipitates and its effects on sulfate reducing bacteria (SRB) in copper-containing waste stream were evaluated in this study.The elemental composition of the microbial precipitate was studied using electrodispersive X-ray spectroscopy (EDX),and it was found that the ratio of S:Cu was 1.12.Combining with the results of copper distribution in the SRB metabolism culture,which was analyzed by the sequential extraction procedure,copper in the precipitates was determined as covellite (CuS).The bacterially produced precipitates caused a decrease of the sulfate reduction rate,and the more precipitates were generated,the lower the sulfate reduction rate was.The particle sizes of bacterially generated covellite were ranging from 0.03 to 2 m by particles size distribution (PSD) analysis,which was smaller than that of the SRB cells.Transmission electron microscopy (TEM) analysis showed that the microbial covellite was deposited on the surface of the cell.The effects of the microbial precipitate on SRB metabolism were found to be weakened by increasing the precipitation time and adding microbial polymeric substances in later experiments.These results provided direct evidence that the SRB activity was inhibited by the bacterially produced covellite,which enveloped the bacterium and thus affected the metabolism of SRB on mass transfer.

  15. Conditions for precipitation of copper phases in DWPF waste glass

    International Nuclear Information System (INIS)

    Schumacher, R.F.; Ramsey, W.G.

    1993-01-01

    The Defense Waste Processing Facility (DWPF) precipitate hydrolysis process requires the use of copper formate catalyst. The expected absorbed radiation doses to the precipitate require levels of copper formate that increase the potential for the precipitation of metallic copper in the DWPF Melter. The conditions required to avoid the precipitation of copper are described

  16. Process development for recovery of copper and precious metals from waste printed circuit boards with emphasize on palladium and gold leaching and precipitation.

    Science.gov (United States)

    Behnamfard, Ali; Salarirad, Mohammad Mehdi; Veglio, Francesco

    2013-11-01

    A novel hydrometallurgical process was proposed for selective recovery of Cu, Ag, Au and Pd from waste printed circuit boards (PCBs). More than 99% of copper content was dissolved by using two consecutive sulfuric acid leaching steps in the presence of H2O2 as oxidizing agents. The solid residue of 2nd leaching step was treated by acidic thiourea in the presence of ferric iron as oxidizing agent and 85.76% Au and 71.36% Ag dissolution was achieved. The precipitation of Au and Ag from acidic thiourea leachate was investigated by using different amounts of sodium borohydride (SBH) as a reducing agent. The leaching of Pd and remained gold from the solid reside of 3rd leaching step was performed in NaClO-HCl-H2O2 leaching system and the effect of different parameters was investigated. The leaching of Pd and specially Au increased by increasing the NaClO concentration up to 10V% and any further increasing the NaClO concentration has a negligible effect. The leaching of Pd and Au increased by increasing the HCl concentration from 2.5 to 5M. The leaching of Pd and Au were endothermic and raising the temperature had a positive effect on leaching efficiency. The kinetics of Pd leaching was quite fast and after 30min complete leaching of Pd was achieved, while the leaching of Au need a longer contact time. The best conditions for leaching of Pd and Au in NaClO-HCl-H2O2 leaching system were determined to be 5M HCl, 1V% H2O2, 10V% NaClO at 336K for 3h with a solid/liquid ratio of 1/10. 100% of Pd and Au of what was in the chloride leachate were precipitated by using 2g/L SBH. Finally, a process flow sheet for the recovery of Cu, Ag, Au and Pd from PCB was proposed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. A Prototype Physical Database for Passive Microwave Retrievals of Precipitation over the US Southern Great Plains

    Science.gov (United States)

    Ringerud, S.; Kummerow, C. D.; Peters-Lidard, C. D.

    2015-01-01

    An accurate understanding of the instantaneous, dynamic land surface emissivity is necessary for a physically based, multi-channel passive microwave precipitation retrieval scheme over land. In an effort to assess the feasibility of the physical approach for land surfaces, a semi-empirical emissivity model is applied for calculation of the surface component in a test area of the US Southern Great Plains. A physical emissivity model, using land surface model data as input, is used to calculate emissivity at the 10GHz frequency, combining contributions from the underlying soil and vegetation layers, including the dielectric and roughness effects of each medium. An empirical technique is then applied, based upon a robust set of observed channel covariances, extending the emissivity calculations to all channels. For calculation of the hydrometeor contribution, reflectivity profiles from the Tropical Rainfall Measurement Mission Precipitation Radar (TRMM PR) are utilized along with coincident brightness temperatures (Tbs) from the TRMM Microwave Imager (TMI), and cloud-resolving model profiles. Ice profiles are modified to be consistent with the higher frequency microwave Tbs. Resulting modeled top of the atmosphere Tbs show correlations to observations of 0.9, biases of 1K or less, root-mean-square errors on the order of 5K, and improved agreement over the use of climatological emissivity values. The synthesis of these models and data sets leads to the creation of a simple prototype Tb database that includes both dynamic surface and atmospheric information physically consistent with the land surface model, emissivity model, and atmospheric information.

  18. Synthesis of hydroxyapatite nanorods for application in water defluoridation and optimization of process variables: Advantage of ultrasonication with precipitation method over conventional method.

    Science.gov (United States)

    Mehta, Dhiraj; Mondal, Poonam; Saharan, Virendra Kumar; George, Suja

    2017-07-01

    This research work presents the synthesis of hydroxyapatite (Hap) nanorods for defluoridation of drinking water by using both conventional (CM) and ultrasonication with precipitation (USPM) methods. Calcium nitrate was reacted with potassium phosphate in presence of ammonia for controlled pH to synthesize Hap nanorods, which was characterized using FTIR, XRD, SEM, TG-DTA, and TEM/EDS for determining its phase composition, structural and thermal decomposition behavior. When USPM method was used for synthesis, the yield of the Hap nanorods was improved from 83.24±1.0% to 90.2±1.0%, and complete phase transformation occurred with formation of elongated Hap nanorods. Effects of process parameters such as solution pH, contact time and adsorbent dose were studied through response surface methodology (RSM). A simple quadratic model was developed using Central Composite Design (CCD) and optimum parameters for fluoride adsorption process were determined to be pH 7, contact time 3h and adsorbent dose 7g/L for maximum removal capacity. Fluoride removal efficiency was predicted to be 93.64% which was very close to the experimental value obtained at 92.86% using ultrasonically prepared Hap. Fluoride adsorption isotherms fitted the Freundlich isotherm with an adsorption capacity of 1.49mg/g, while the kinetic studies revealed that the process followed pseudo-second order model. The treated water quality parameters such as residual fluoride, calcium leached, total hardness and alkalinity was investigated, and it was observed that all these parameters were within the permissible limits as per WHO and BIS standards. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Yu-Wei [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yang, Ko-Ho, E-mail: yangkoho@cc.kuas.edu.tw [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Dental Materials Research Center, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yeh, Sung-Wei [Metal Industries Research and Development Centre, 1001 Kaohsiung Highway, Kaohsiung 811, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100, Shihchuan 1st Road, Kaohsiung 80728, Taiwan (China)

    2011-06-16

    Highlights: > The thermal behavior of 3Y-TZP precursor powders had been investigated. > The crystallization behavior of 3Y-TZP nanopowders had been investigated. > The activation energy for crystallization of tetragonal ZrO{sub 2} was obtained. > The growth morphology parameter n is approximated as 2.0. > The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO{sub 2} crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 {+-} 21.9 kJ mol{sup -1}, was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO{sub 2} was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

  20. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders prepared by the co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian-Chih [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Chen, Wen-Cheng [School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Tien, Yin-Chun [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Shih, Chi-Jen, E-mail: cjshih@kmu.edu.t [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan1st Road, Kaohsiung 80708, Taiwan (China)

    2010-04-30

    Cerium oxide nanocrystallites were synthesized by a co-precipitation process at a relatively low temperature, using cerium (III) nitrate as the starting material in a water solution with pH in the range of 8-9. The effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K, by XRD analysis. When calcined at temperatures from 473 to 1273 K, face-centered cubic phase crystallization was observed by XRD. The crystallite size of the cerium oxide increased from 12.0 to 48 nm as the calcining temperature increased from 473 to 1273 K, in the pH range 8-9. The activation energy for the growth of cerium oxide nanoparticles was found to have very low values of 17.5 kJ/mol for pH = 8 and 16.0 kJ/mol for pH = 9.

  1. Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

    International Nuclear Information System (INIS)

    Hsu, Yu-Wei; Yang, Ko-Ho; Chang, Kuo-Ming; Yeh, Sung-Wei; Wang, Moo-Chin

    2011-01-01

    Highlights: → The thermal behavior of 3Y-TZP precursor powders had been investigated. → The crystallization behavior of 3Y-TZP nanopowders had been investigated. → The activation energy for crystallization of tetragonal ZrO 2 was obtained. → The growth morphology parameter n is approximated as 2.0. → The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO 2 crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 ± 21.9 kJ mol -1 , was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO 2 was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

  2. Titanium nitride (TiN) precipitation in a maraging steel during the vacuum arc remelting (VAR) process - Inclusions characterization and modeling

    Science.gov (United States)

    Descotes, V.; Bellot, J.-P.; Perrin-Guérin, V.; Witzke, S.; Jardy, A.

    2016-07-01

    Titanium Nitride (TiN) inclusions are commonly observed in a Maraging steel containing Nitrogen and Titanium and remelted in a VAR furnace. They can be easily detected by optical microscopy. A nucleus is observed next to a large number of TiN inclusions. A TEM analysis was carried out on a biphasic nucleus composed of a calcium sulfide (CaS) and a spinel (MgAl2O4), surrounded by a TiN particle. An orientation relationship between these three phases was revealed, which suggests a heterogeneous germination of the TiN particle on the nucleus by epitaxial growth. Based on this observation, on thermodynamic considerations and on previous work, a model has been developed and coupled to a numerical simulation of the VAR process to study the formation and evolution of a TiN distribution in the VAR ingot. Microsegregation is modeled using the lever rule, while the kinetics of precipitation is mainly driven by the supersaturation of the liquid bath. This model highlights the influence of the melt rate on the final size of TiN particles.

  3. Aluminum precipitation from Hanford DSSF

    International Nuclear Information System (INIS)

    Borgen, D.; Frazier, P.; Staton, G.

    1994-01-01

    A series of pilot scale tests using simulated Double Shell Slurry Feed (DSSF) showed that well-settled aluminum precipitate can be produced in Hanford double shell tank (DST) high level waste by slow neutralization with carbon dioxide. This pretreatment could provide an early grout feed and free tank space, as well as facilitate downstream processes such as ion exchange by providing a less caustic feed. A total of eight test runs were completed using a 10-ft tall 3-in i.d. glass column. The 10-ft height corresponds to about one third of the vertical height of a DST, hence providing a reasonable basis for extrapolating the observed precipitate settling and compaction to the actual waste tank environment. Four runs (three with a simplified simulant and one with a chemically complete simulant) produced well settled precipitates averaging 1.5 to 2 feet high. Aluminum gel rather than settled precipitate resulted from one test where neutralization was too rapid

  4. Preparation of (U, Gd)O2 by inverse co-precipitation in nitric solutions. Study of homogeneity and process optimization

    International Nuclear Information System (INIS)

    Marchi, Daniel E.; Menghini, Jorge E.; Trimarco, Viviana G.

    1999-01-01

    The inverse co-precipitation method has been used at the laboratory level to produce uranium - gadolinium mixed oxides. The formation of a mixed phase in the precipitates has been determined as well as the occurrence of only one phase in the sintered pellets, corresponding to a gadolinium - uranium solution. Moreover, a modification in the calcination-reduction stage was introduced that allows the elimination of the fissures previously detected in the sintered pellets

  5. The influence of welding and post heat treatment parameters on the diffusion and precipitation processes in dissimilar metal joints of a 1% and a 12% Cr-steel

    International Nuclear Information System (INIS)

    Kullik, M.; Katerbau, K.H.

    1989-05-01

    The influences of different weld metals, welding processes and post weld heat treatments (PWHT) on mechanical properties, carbon diffusion and precipitation processes were investigated by studying dissimilar metal welds between the cast steel GS-17 CrMoV 5 11 (1% Cr) and the steel X 20 CrMoV 12 1 (12% Cr). By means of tensile and impact tests, metallographic investigation, hardness measurements, electron beam X-ray microanalysis and transmission electron microscope examination changes in the welded joints were shown after different PWHT's as well as after creep tests. It was found that the joint with a 5% CrMoV-weld metal shows higher yield and rupture strength than the joint with a 12% CrMoV-weld metal. With increasing heat input during PWHT the strength decreases for both welds, but always remains higher than the values of the base materials. During PWTH as well as during service at elevated temperatures carbon diffuses from the lower chromium material to the higher chromium material. Width and carbon concentration of the carburized and decarburized zones depend on the heat input. A simple diffusion model was developed to describe the carbon profile for any annealing time and temperature. The consequence of the decarburization is a microstructural change in the heat effected zone of the cast steel. During longer annealing the fine M 2 C-carbides dissolve and coarse M 6 C-crbides form, resulting in a lower creep ductility of this zone. (orig.) With 19 refs., 15 tabs., 104 figs [de

  6. Uranium precipitation with hydrogen peroxide

    International Nuclear Information System (INIS)

    Brown, R.A.

    1980-01-01

    Although hydrogen peroxide precipitation of uranium continues to be used primarily as means of producing a high purity yellowcake, it has also become an important process due to its superior physical properties. Processing costs such as filtering, drying and/or calcining and drumming, can be reduced. 5 refs

  7. Metabolic fingerprinting of high-fat plasma samples processed by centrifugation- and filtration-based protein precipitation delineates significant differences in metabolite information coverage.

    Science.gov (United States)

    Barri, Thaer; Holmer-Jensen, Jens; Hermansen, Kjeld; Dragsted, Lars O

    2012-03-09

    Metabolomics and metabolic fingerprinting are being extensively employed for improved understanding of biological changes induced by endogenous or exogenous factors. Blood serum or plasma samples are often employed for metabolomics studies. Plasma protein precipitation (PPP) is currently performed in most laboratories before LC-MS analysis. However, the impact of fat content in plasma samples on metabolite coverage has not previously been investigated. Here, we have studied whether PPP procedures influence coverage of plasma metabolites from high-fat plasma samples. An optimized UPLC-QTOF/MS metabolic fingerprinting approach and multivariate modeling (PCA and OPLS-DA) were utilized for finding characteristic metabolite changes induced by two PPP procedures; centrifugation and filtration. We used 12-h fasting samples and postprandial samples collected at 2h after a standardized high-fat protein-rich meal in obese non-diabetic subjects recruited in a dietary intervention. The two PPP procedures as well as external and internal standards (ISs) were used to track errors in response normalization and quantification. Remarkably and sometimes uniquely, the fPPP, but not the cPPP approach, recovered not only high molecular weight (HMW) lipophilic metabolites, but also small molecular weight (SMW) relatively polar metabolites. Characteristic SMW markers of postprandial samples were aromatic and branched-chain amino acids that were elevated (p<0.001) as a consequence of the protein challenge. In contrast, some HMW lipophilic species, e.g. acylcarnitines, were moderately lower (p<0.001) in postprandial samples. LysoPCs were largely unaffected. In conclusion, the fPPP procedure is recommended for processing high-fat plasma samples in metabolomics studies. While method improvements presented here were clear, use of several ISs revealed substantial challenges to untargeted metabolomics due to large and variable matrix effects. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Effective assimilation of global precipitation: simulation experiments

    Directory of Open Access Journals (Sweden)

    Guo-Yuan Lien

    2013-07-01

    Full Text Available Past attempts to assimilate precipitation by nudging or variational methods have succeeded in forcing the model precipitation to be close to the observed values. However, the model forecasts tend to lose their additional skill after a few forecast hours. In this study, a local ensemble transform Kalman filter (LETKF is used to effectively assimilate precipitation by allowing ensemble members with better precipitation to receive higher weights in the analysis. In addition, two other changes in the precipitation assimilation process are found to alleviate the problems related to the non-Gaussianity of the precipitation variable: (a transform the precipitation variable into a Gaussian distribution based on its climatological distribution (an approach that could also be used in the assimilation of other non-Gaussian observations and (b only assimilate precipitation at the location where at least some ensemble members have precipitation. Unlike many current approaches, both positive and zero rain observations are assimilated effectively. Observing system simulation experiments (OSSEs are conducted using the Simplified Parametrisations, primitivE-Equation DYnamics (SPEEDY model, a simplified but realistic general circulation model. When uniformly and globally distributed observations of precipitation are assimilated in addition to rawinsonde observations, both the analyses and the medium-range forecasts of all model variables, including precipitation, are significantly improved as compared to only assimilating rawinsonde observations. The effect of precipitation assimilation on the analyses is retained on the medium-range forecasts and is larger in the Southern Hemisphere (SH than that in the Northern Hemisphere (NH because the NH analyses are already made more accurate by the denser rawinsonde stations. These improvements are much reduced when only the moisture field is modified by the precipitation observations. Both the Gaussian transformation and

  9. Modelled Precipitation Over Greenland

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes the annual total precipitation from 1985 to 1999 and monthly total precipitation from January 1985 to December 1999. The data is derived from...

  10. Precipitation and Hardening in Magnesium Alloys

    Science.gov (United States)

    Nie, Jian-Feng

    2012-11-01

    Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

  11. Development and demonstration of process and components for the control of aluminum-air-battery electrolyte composition through the precipitation of aluminum trihydroxide. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, T. G.; Misra, C.

    1982-05-11

    Physical property data on density, viscosity, and electrical conductivity were developed and reduced to correlation form for synthetic electrolytes containing nominally 7 g/L Sn and 0.20 g/L Ga in 3,4,5,6 M NaOH. Concentrations of Al(OH)/sub 4/ were selected at six levels for each NaOH concentration and ranged from 0 to as high as 4 M Al(OH)/sub 4/ at 6 M NaOH. Measurements of each property were made at 25, 40, 60, and 80 C. The effect of the Sn and Ga impurities was to increase density by a relatively small percentage, increase viscosity by a significant percentage, and decrease electrical conductance by a significant percentage. Isothermal, batch precipitation experiments at 40, 60, and 80 C were utilized to develop data from which kinetic and solubility correlations were derived as functions of electrolyte and system parameters. Precipitation rate was negatively affected by tin in solution, with a 40% reduction in the rate constant being attributed to 0.06 M Sn. Both Sn and Ga co-precipitated with the Al(OH)/sub 3/ to an extent strongly dependent on temperature. Very high precipitation rates resulted in Na levels in product exceeding the target level of 0.24% Na on the hydrate basis. The incorporation of Na in product was also a strong function of temperature. A total of 108 computer simulations were performed and documented to delineate the region of feasible operation with respect to meeting the aluminate production specification. A full-scale precipitator was operated in a continuous mode to assess production rate, population changes with time, and hardware aspects. A digester was used to perform the function of an Al-Air battery, that is to drive Al(OH)/sub 4//sup -/ into solution. Results are presented in detail. (WHK)

  12. Silver precipitation from electrolytic effluents

    International Nuclear Information System (INIS)

    Rivera, I.; Patino, F.; Cruells, M.; Roca, A.; Vinals, J.

    2004-01-01

    The recovery of silver contained in electrolytic effluents is attractive due to its high economic value. These effluents are considered toxic wastes and it is not possible to dump them directly without any detoxification process. One of the most important way for silver recovery is the precipitation with sodium ditionite, sodium borohidride or hydrazine monohidrate. In this work, the most significant aspects related to the use of these reagents is presented. Results of silver precipitation with sodium ditionite from effluents containing thiosulfate without previous elimination of other species are also presented. silver concentration in the final effluents w <1 ppm. (Author) 15 refs

  13. The characterisation of precipitated magnetites

    International Nuclear Information System (INIS)

    Rush, D.F.; Segal, D.L.

    1982-06-01

    Methods are described for the preparation of magnetite by precipitation from aqueous solutions of iron(II) and iron(III) salts. The magnetites have been characterised by transmission electron microscopy, chemical analysis and X-ray diffraction. Transmission Moessbauer spectroscopy has also been used to characterise precipitated magnetites and a comparison of the spectra has been made with those obtained from nickel ferrite and hydrated ferric oxides. The hydrothermal stability of magnetite at 573 K has also been investigated. This work is relevant to corrosion processes that can occur in the water coolant circuits of nuclear reactors. (author)

  14. Precipitation of uranium concentrates by hydrogen peroxide

    International Nuclear Information System (INIS)

    Barbosa Filho, O.

    1986-12-01

    An experimental study on the (UO 4 .xH 2 ) uranyl peroxide precipitation from a uranium process strip solution is presented. The runs were performed in a batch reactor, in laboratory scale. The main objective was to assess the possibility of the peroxide route as an alternative to a conventional ammonium diuranate process. The chemical composition of process solution was obtained. The experiments were conducted according to a factorial design, aiming to evaluate the effects of initial pH, precipitation pH and H 2 O 2 /UO 2 2+ ratio upon the process. The responses were measured in terms of the efficiency of U precipitation, the content of U in the precipitates and the distribution of impurities in the precipitates. The results indicated that the process works is satisfactory on the studied conditions and depending on conditions, it is possible to achieve levels of U precipitation efficiency greater than 99.9% in reaction times of 2 hours. The precipitates reach grades around 99% U 3 O 8 after calcination (900 0 C) and impurities fall below the limit for penalties established by the ASTM and the Allied Chemical Standards. The precipitates are composed of large aggregates of crystals of 1-4 μm, are fast settling and filtering, and are free-flowing when dry. (Author) [pt

  15. Salts-based size-selective precipitation: toward mass precipitation of aqueous nanoparticles.

    Science.gov (United States)

    Wang, Chun-Lei; Fang, Min; Xu, Shu-Hong; Cui, Yi-Ping

    2010-01-19

    Purification is a necessary step before the application of nanocrystals (NCs), since the excess matter in nanoparticles solution usually causes a disadvantage to their subsequent coupling or assembling with other materials. In this work, a novel salts-based precipitation technique is originally developed for the precipitation and size-selective precipitation of aqueous NCs. Simply by addition of salts, NCs can be precipitated from the solution. After decantation of the supernatant solution, the precipitates can be dispersed in water again. By means of adjusting the addition amount of salt, size-selective precipitation of aqueous NCs can be achieved. Namely, the NCs with large size are precipitated preferentially, leaving small NCs in solution. Compared with the traditional nonsolvents-based precipitation technique, the current one is simpler and more rapid due to the avoidance of condensation and heating manipulations used in the traditional precipitation process. Moreover, the salts-based precipitation technique was generally available for the precipitation of aqueous nanoparticles, no matter if there were semiconductor NCs or metal nanoparticles. Simultaneously, the cost of the current method is also much lower than that of the traditional nonsolvents-based precipitation technique, making it applicable for mass purification of aqueous NCs.

  16. Waste and Simulant Precipitation Issues

    International Nuclear Information System (INIS)

    Steele, W.V.

    2000-01-01

    As Savannah River Site (SRS) personnel have studied methods of preparing high-level waste for vitrification in the Defense Waste Processing Facility (DWPF), questions have arisen with regard to the formation of insoluble waste precipitates at inopportune times. One option for decontamination of the SRS waste streams employs the use of an engineered form of crystalline silicotitanate (CST). Testing of the process during FY 1999 identified problems associated with the formation of precipitates during cesium sorption tests using CST. These precipitates may, under some circumstances, obstruct the pores of the CST particles and, hence, interfere with the sorption process. In addition, earlier results from the DWPF recycle stream compatibility testing have shown that leaching occurs from the CST when it is stored at 80 C in a high-pH environment. Evidence was established that some level of components of the CST, such as silica, was leached from the CST. This report describes the results of equilibrium modeling and precipitation studies associated with the overall stability of the waste streams, CST component leaching, and the presence of minor components in the waste streams

  17. A review of United States yellow cake precipitation practice

    International Nuclear Information System (INIS)

    Litz, J.E.; Coleman, R.B.

    1980-01-01

    The various process flowsheets used to produce concentrated uranium solutions are reviewed. The choices of flowsheets are affected by ore alkalinity, uranium mineralization, and the impurities solubilized during leaching. The techniques used to precipitate yellow cake from concentrated uranium solutions are reviewed. Consideration is given to precipitation chemistry, reagent requirements, and process equipment and costs for precipitation, dewatering, drying and calcining. (author)

  18. CEOS precipitation constellation

    Science.gov (United States)

    Neeck, Steven P.; Oki, Riko

    2007-10-01

    The outcomes of the 19th Committee on Earth Observing Satellites (CEOS) Plenary held in London in November 2005, recognized that the CEOS Implementation Plan for Space-Based Observations for Global Earth Observation System of Systems (GEOSS) should: - identify the supply of space-based observations required to satisfy the requirements expressed by the 10-year implementation plan for GEOSS; and - propose an innovative process whereby the many disparate types of Earth observing programs funded by CEOS Member agencies might contribute to the supply of the required observations. The CEOS Task Force charged with drafting the CEOS Implementation Plan for Space-Based Observations for GEOSS focused its early efforts on the creation of a 'new planning process' which would satisfy the various criteria demanded by member space agencies, and which would hopefully encourage a new phase of specificity and focus in the multi-lateral co-operation efforts undertaken by space agencies under the CEOS umbrella - resulting in improved engagement of all CEOS Members and real implementation results. The CEOS Constellations is the title given to this new process, and four pilot studies have been initiated in order to pioneer and test the concept. The Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration (NASA) were selected as the lead agencies for the study of the development of a CEOS Precipitation Constellation with the support of other CEOS space agency and user community participants. The goals, approach, and anticipated outcomes for the study will be discussed.

  19. Uranium peroxide precipitate drying temperature relationships

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, C.; Dyck, B., E-mail: chick_rodgers@cameco.com [Cameco Corp., Saskatoon, SK (Canada)

    2010-07-01

    Cameco Corporation is in the process of revitalizing the mill at its Key Lake operation in northern Saskatchewan. The current Key Lake process employs ammonia stripping and ammonia precipitation. As part of the revitalization, the company is considering installing strong acid stripping in solvent extraction as used at its Rabbit Lake operation. This change would lead to using hydrogen peroxide for uranium precipitation. As part of the process evaluation, tests were carried out to study how changes in the temperature of an indirect fired dryer affected the properties of uranium peroxide [yellowcake] precipitate. This paper discusses the results of the test work, including the relationships between drying temperature and the following: (author)

  20. Evaluation of Model Microphysics Within Precipitation Bands of Extratropical Cyclones

    Science.gov (United States)

    Colle, Brian A.; Molthan, Andrew; Yu, Ruyi; Stark, David; Yuter, Sandra; Nesbitt, Steven

    2013-01-01

    Recent studies evaluating the bulk microphysical schemes (BMPs) within cloud resolving models (CRMs) have indicated large uncertainties and errors in the amount and size distributions of snow and cloud ice aloft. The snow prediction is sensitive to the snow densities, habits, and degree of riming within the BMPs. Improving these BMPs is a crucial step toward improving both weather forecasting and climate predictions. Several microphysical schemes in the Weather Research and Forecasting (WRF) model down to 1.33-km grid spacing are evaluated using aircraft, radar, and ground in situ data from the Global Precipitation Mission Coldseason Precipitation Experiment (GCPEx) experiment, as well as a few years (15 winter storms) of surface measurements of riming, crystal habit, snow density, and radar measurements at Stony Brook, NY (SBNY on north shore of Long Island) during the 2009-2012 winter seasons. Surface microphysical measurements at SBNY were taken every 15 to 30 minutes using a stereo microscope and camera, and snow depth and snow density were also recorded. During these storms, a vertically-pointing Ku-band radar was used to observe the vertical evolution of reflectivity and Doppler vertical velocities. A Particle Size and Velocity (PARSIVEL) disdrometer was also used to measure the surface size distribution and fall speeds of snow at SBNY. For the 15 cases at SBNY, the WSM6, Morrison (MORR), Thompson (THOM2), and Stony Brook (SBU-YLIN) BMPs were validated. A non-spherical snow assumption (THOM2 and SBU-YLIN) simulated a more realistic distribution of reflectivity than spherical snow assumptions in the WSM6 and MORR schemes. The MORR, WSM6, and SBU-YLIN schemes are comparable to the observed velocity distribution in light and moderate riming periods. The THOM2 is 0.25 meters per second too slow with its velocity distribution in these periods. In heavier riming, the vertical Doppler velocities in the WSM6, THOM2, and MORR schemes were 0.25 meters per second too

  1. Rheology of tetraphenylborate precipitate slurry

    International Nuclear Information System (INIS)

    Goren, I.D.; Martin, H.D.; McLain, M.A.

    1985-01-01

    The rheological properties of tetraphenylborate precipitate slurry were determined. This nonradioactive slurry simulates the radioactive tetraphenylborate precipitate generated at the Savannah River Plant by the In-Tank Precipitation Process. The data obtained in this study was applied in the design of slurry pumps, transfer pumps, transfer lines, and vessel agitation for the Defense Waste Processing Facility and other High Level Waste treatment projects. The precipitate slurry behaves as a Bingham plastic. The yield stress is directly proportional to the concentration of insoluble solids over the range of concentrations studied. The consistency is also a linear function of insoluble solids over the same concentration range. Neither the yield stress nor the consistency was observed to be affected by the presence of the soluble solids. Temperature effects on flow properties of the slurry were also examined: the yield stress is inversely proportional to temperature, but the consistency of the slurry is independent of temperature. No significant time-dependent effects were found. 4 refs., 4 figs., 3 tabs

  2. Global Precipitation Measurement Poster

    Science.gov (United States)

    Azarbarzin, Art

    2010-01-01

    This poster presents an overview of the Global Precipitation Measurement (GPM) constellation of satellites which are designed to measure the Earth's precipitation. It includes the schedule of launches for the various satellites in the constellation, and the coverage of the constellation, It also reviews the mission capabilities, and the mission science objectives.

  3. Precipitation kinetics of a continuous precipitator, with application to the precipitation of ammonium polyuranate

    International Nuclear Information System (INIS)

    Hoyt, R.C.

    1978-04-01

    A mathematical model describing the kinetics of continuous precipitation was developed which accounts for crystal nucleation, crystal growth, primary coagulation, and secondary coagulation. Population density distributions, average particle sizes, dominant particle sizes, and suspension density fractions of the crystallites, primary agglomerates, and secondary agglomerates leaving the continuous precipitator can be determined. This kinetic model was applied to the continuous precipitation of ammonium polyuranate, which consists of: (1) elementary crystals, (2) clusters or primary coagulated particles, and (3) agglomerates or secondary coagulated particles. The crystallites are thin, submicron, hexagonal platelets. The clusters had an upper size limit of about 7 μ in diameter and contained numerous small voids (less than 0.3 μm) due to the packing of the crystallites. The agglomerates had an upper size limit of about 40 μm in diameter and contained large voids (approximately 1 μm). The particle size distribution and particle structure of the ammonium polyuranate precipitate can be controlled through proper regulation of the precipitation conditions. The ratio of clusters to agglomerates can be best controlled through the uranium concentration, and the cohesiveness or internal bonding strength of the particles can be controlled with the ammonium to uranium reacting feed mole ratio. These two conditions, in conjunction with the residence time, will determine the nucleation rates, growth rates, and size distributions of the particles leaving the continuous precipitator. With proper control of these physical particle characteristics, the use of pore formers, ball-milling, and powder blending can probably be eliminated from the nuclear fuel fabrication process, substantially reducing the cost

  4. Precipitation kinetics of a continuous precipitator, with application to the precipitation of ammonium polyuranate

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, R.C.

    1978-04-01

    A mathematical model describing the kinetics of continuous precipitation was developed which accounts for crystal nucleation, crystal growth, primary coagulation, and secondary coagulation. Population density distributions, average particle sizes, dominant particle sizes, and suspension density fractions of the crystallites, primary agglomerates, and secondary agglomerates leaving the continuous precipitator can be determined. This kinetic model was applied to the continuous precipitation of ammonium polyuranate, which consists of: (1) elementary crystals, (2) clusters or primary coagulated particles, and (3) agglomerates or secondary coagulated particles. The crystallites are thin, submicron, hexagonal platelets. The clusters had an upper size limit of about 7 ..mu.. in diameter and contained numerous small voids (less than 0.3 ..mu..m) due to the packing of the crystallites. The agglomerates had an upper size limit of about 40 ..mu..m in diameter and contained large voids (approximately 1 ..mu..m). The particle size distribution and particle structure of the ammonium polyuranate precipitate can be controlled through proper regulation of the precipitation conditions. The ratio of clusters to agglomerates can be best controlled through the uranium concentration, and the cohesiveness or internal bonding strength of the particles can be controlled with the ammonium to uranium reacting feed mole ratio. These two conditions, in conjunction with the residence time, will determine the nucleation rates, growth rates, and size distributions of the particles leaving the continuous precipitator. With proper control of these physical particle characteristics, the use of pore formers, ball-milling, and powder blending can probably be eliminated from the nuclear fuel fabrication process, substantially reducing the cost.

  5. Interannual variation of annual precipitation and urban effect on precipitation in the Beijing region

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960-2000 annual precipitation observations at 20 stations in the Beijing region. The results show that: the annual precipitation in the Beijing region possesses the large scale variation character with the linear trend of - 1.197/10 yr, which corresponds to a total reduction of 27.82 mm in annual precipitation in the 41 years; the local annual precipitation anomalies (percent of the normal 1960-2000) show a positive center near the urban area, i.e. urban precipitation island (UPI), whose intensity increases with the linear trend of 0. 6621%/10 yr, opposite to the interannual trend of large scale precipitation over the Beijing region; changes in the UPI are also associated with the intensity of synoptic processes of precipitation, and when the synoptic processes are strong (wet years), the intensity of UPI strengthens, while the synoptic processes are weak (dry years), and the UPI disappears in the Beijing region.

  6. Precipitation behaviors of X70 acicular ferrite pipeline steel

    Institute of Scientific and Technical Information of China (English)

    Hao Yu; Yi Sun; Qixiang Chen; Haitao Jiang; Lihong Zhang

    2006-01-01

    The morphology, structure, and chemical composition of precipitates in the final microstructure of Nb-V-Ti microalloyed X70 acicular ferrite pipeline steel were investigated using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Precipitates observed by TEM can be classified into two groups. The large precipitates are complex compounds that comprise square-shaped TiN precipitate as core with fine Nb-containing precipitate nucleated on pre-existing TiN precipitate as caps on one or more faces at high temperature. In contrast, the fine and spherical Nb carbides and/or carbonitrides precipitate heterogeneously on dislocations and sub-boundaries at low temperature. From the analysis in terms of thermodynamics, EDS and chemical composition of the steel, NbC precipitation is considered to be the predominant precipitation behavior in the tested steel under the processing conditions of this research.

  7. Global precipitations and climate change. Proceedings

    International Nuclear Information System (INIS)

    Desbois, M.; Desalmand, F.

    1994-01-01

    The workshop reviewed the present status of knowledge concerning the past and present evolution of the distribution of precipitations at global scale, related to climate evolution at different time scales. This review was intended to assess the availability and quality of data which could help, through validation and initialization of model studies, to improve our understanding of the processes determining these precipitation changes. On another hand, the modelling specialists presented their actual use of precipitation data. Exchanges of views between the modelling and observing communities were thus made possible, leading to a set of recommendations for future studies. Sessions were then devoted to specific themes: 1) Paleoclimatology, 2) data collection, history and statistics, programmes, 3) methodologies and accuracy of large scale estimation of precipitation from conventional data, 4) estimation of precipitation from satellite data, 5) modelling studies. (orig.)

  8. Precipitates in irradiated Zircaloy

    International Nuclear Information System (INIS)

    Chung, H.M.

    1985-10-01

    Precipitates in high-burnup (>20 MWd/kg U) Zircaloy spent-fuel cladding discharged from commercial boiling- and pressurized-water reactors have been characterized by TEM-HVEM. Three classes of primary precipitates were observed in the irradiated Zircaloys: Zr 3 O (2 to 6 nm), cubic-ZrO 2 (greater than or equal to 10 nm), and delta-hydride (35 to 100 nm). The former two precipitations appears to be irradiation induced in nature. Zr(Fe/sub x/Cr/sub 1-x/) 2 and Zr 2 (Fe/sub x/Ni/sub 1-x/) intermetallics, which are the primary precipitates in unirradiated Zircaloys, were largely dissolved after the high burnup. It seems, therefore, that the influence of the size and distribution of the intermetallics on the corrosion behavior may be quite different for the irradiated Zircaloys

  9. WPA Precipitation Tabulations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly precipitation data tabulated under the Work Projects Administration (WPA), a New Deal program created to reduce unemployment during the Great Depression....

  10. The Role of Aerosols in Convective Processes during the Midsummer Drought in the Caribbean

    Directory of Open Access Journals (Sweden)

    Nathan Hosannah

    2015-01-01

    Full Text Available Saharan dust (SD heavily impacts convective precipitation in the Caribbean. To better understand the role of SD in precipitation development during the midsummer drought (MSD, an observational campaign, centered at the city of Mayagüez, Puerto Rico (18.21 N, 67.13 W, between 3 June and 15 July 2014, was conducted in order to select a range of atmospheric conditions to be simulated using the Regional Atmospheric Modeling System (RAMS cloud resolving model under “no SD” and “SD” conditions. The events included one dry day with moderate-heavy SD, one localized moderate rainfall event with moderate SD, one island-wide light precipitation event with heavy SD, and one island-wide heavy precipitation event with light-moderate SD. Model results show that (1 precipitation results are improved when compared with observation with the presence of SD, (2 precipitation, cloud fraction, dew point temperatures, and humidity are significantly reduced under SD conditions, (3 precipitation can occur when SD is removed for a dry day, (4 there is evidence of rain being delayed due to the presence of SD without rainfall intensity or accumulation increases, (5 liquid mixing ratio increases of up to 1.4 g kg−1 occur in the absence of SD, and (6 vertical wind increases of up to 0.8 m s−1 occur in the absence of SD.

  11. Precipitation patterns during channel flow

    Science.gov (United States)

    Jamtveit, B.; Hawkins, C.; Benning, L. G.; Meier, D.; Hammer, O.; Angheluta, L.

    2013-12-01

    Mineral precipitation during channelized fluid flow is widespread in a wide variety of geological systems. It is also a common and costly phenomenon in many industrial processes that involve fluid flow in pipelines. It is often referred to as scale formation and encountered in a large number of industries, including paper production, chemical manufacturing, cement operations, food processing, as well as non-renewable (i.e. oil and gas) and renewable (i.e. geothermal) energy production. We have studied the incipient stages of growth of amorphous silica on steel plates emplaced into the central areas of the ca. 1 meter in diameter sized pipelines used at the hydrothermal power plant at Hellisheidi, Iceland (with a capacity of ca 300 MW electricity and 100 MW hot water). Silica precipitation takes place over a period of ca. 2 months at approximately 120°C and a flow rate around 1 m/s. The growth produces asymmetric ca. 1mm high dendritic structures ';leaning' towards the incoming fluid flow. A novel phase-field model combined with the lattice Boltzmann method is introduced to study how the growth morphologies vary under different hydrodynamic conditions, including non-laminar systems with turbulent mixing. The model accurately predicts the observed morphologies and is directly relevant for understanding the more general problem of precipitation influenced by turbulent mixing during flow in channels with rough walls and even for porous flow. Reference: Hawkins, C., Angheluta, L., Hammer, Ø., and Jamtveit, B., Precipitation dendrites in channel flow. Europhysics Letters, 102, 54001

  12. Investigating the dependence of SCM simulated precipitation and clouds on the spatial scale of large-scale forcing at SGP

    Science.gov (United States)

    Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

    2017-08-01

    Large-scale forcing data, such as vertical velocity and advective tendencies, are required to drive single-column models (SCMs), cloud-resolving models, and large-eddy simulations. Previous studies suggest that some errors of these model simulations could be attributed to the lack of spatial variability in the specified domain-mean large-scale forcing. This study investigates the spatial variability of the forcing and explores its impact on SCM simulated precipitation and clouds. A gridded large-scale forcing data during the March 2000 Cloud Intensive Operational Period at the Atmospheric Radiation Measurement program's Southern Great Plains site is used for analysis and to drive the single-column version of the Community Atmospheric Model Version 5 (SCAM5). When the gridded forcing data show large spatial variability, such as during a frontal passage, SCAM5 with the domain-mean forcing is not able to capture the convective systems that are partly located in the domain or that only occupy part of the domain. This problem has been largely reduced by using the gridded forcing data, which allows running SCAM5 in each subcolumn and then averaging the results within the domain. This is because the subcolumns have a better chance to capture the timing of the frontal propagation and the small-scale systems. Other potential uses of the gridded forcing data, such as understanding and testing scale-aware parameterizations, are also discussed.

  13. Precipitate resolution in an electron irradiated ni-si alloy

    Science.gov (United States)

    Watanabe, H.; Muroga, T.; Yoshida, N.; Kitajima, K.

    1988-09-01

    Precipitate resolution processes in a Ni-12.6 at% Si alloy under electron irradiation have been observed by means of HVEM. Above 400°C, growth and resolution of Ni 3Si precipitates were observed simultaneously. The detail stereoscopic observation showed that the precipitates close to free surfaces grew, while those in the middle of a specimen dissolved. The critical dose when the precipitates start to shrink increases with increasing the depth. This depth dependence of the precipitate behavior under irradiation has a close relation with the formation of surface precipitates and the growth of solute depleted zone beneath them. The temperature and dose dependence of the resolution rate showed that the precipitates in the solute depleted zone dissolved by the interface controlled process of radiation-enhanced diffusion.

  14. Improved Prediction of Phosphorus Dynamics in Biotechnological Processes by Considering Precipitation and Polyphosphate Formation: A Case Study on Antibiotic Production with Streptomyces coelicolor

    DEFF Research Database (Denmark)

    Bürger, Patrick; Flores-Alsina, Xavier; Arellano-Garcia, Harvey

    2018-01-01

    The multiplicity of physicochemical and biological processes, where phosphorus is involved, makes their accurate prediction using current mathematical models in biotechnology quite a challenge. In this work, an antibiotic production model of Streptomyces coelicolor is chosen as a representative...... approach describing intracellular polyphosphate accumulation and consumption has been developed and implemented. A heuristic re-estimation of selected parameters is carried out to improve overall model performance. The improved process model predicts phosphate dynamics (root mean squared error ≤52h: −90...

  15. Absolute nutrient concentration measurements in cell culture media: 1H q-NMR spectra and data to compare the efficiency of pH-controlled protein precipitation versus CPMG or post-processing filtering approaches

    Directory of Open Access Journals (Sweden)

    Luca Goldoni

    2016-09-01

    Full Text Available The NMR spectra and data reported in this article refer to the research article titled “A simple and accurate protocol for absolute polar metabolite quantification in cell cultures using q-NMR” [1]. We provide the 1H q-NMR spectra of cell culture media (DMEM after removal of serum proteins, which show the different efficiency of various precipitating solvents, the solvent/DMEM ratios, and pH of the solution. We compare the data of the absolute nutrient concentrations, measured by PULCON external standard method, before and after precipitation of serum proteins and those obtained using CPMG (Carr-Purcell-Meiboom-Gill sequence or applying post-processing filtering algorithms to remove, from the 1H q-NMR spectra, the proteins signal contribution. For each of these approaches, the percent error in the absolute value of every measurement for all the nutrients is also plotted as accuracy assessment. Keywords: 1H NMR, pH-controlled serum removal, PULCON, Accuracy, CPMG, Deconvolution

  16. Acid precipitation and forest vegetation

    Energy Technology Data Exchange (ETDEWEB)

    Tamm, C O; Cowling, E B

    1977-04-01

    Effects of acidic precipitation on forest vegetation may be classified as being either direct or indirect. Among the most important direct effects are damage to protective cuticular layers, interference with normal functioning of guard cells, poisoning of plant cells after diffusion of acidic substances through stomata or cuticle and interference with reproductive processes. Indirect effects include accelerated leaching of substances from foliar organs, increased susceptibility to drought and other environmental stress factors, and alteration of symbiotic associations and host-parasite interactions. The potential importance of nutrient uptake through foliage and the need to understand atmosphere-plant-soil interactions are stressed.

  17. Precipitation of ammonium diuranate : a study

    International Nuclear Information System (INIS)

    Krishnamoorthy, T.S.; Mahadevan, N.; Sankar Das, M.

    1991-01-01

    The precipitation of ammonium diuranate (ADU) forms the first step in the production of UO 2 fuel for reactors, and hence the quality and consistency of the ADU precipitate is very important in industrial operations. An investigation, on the precipitation of ADU, was carried out under conditions similar to those in industrial production, to evaluate the effect of various variables on the consistency and the quality of ADU. The variables studied were concentration of uranium and ammonia, pH, temperature and form of ammonia (gas or solution). The properties studied were the settling rate of the precipitates, surface area of the ADUs and calcined oxides and compositional characteristics of the ADUs. Multifactorial experiments and ruggedness tests were applied to identify the parameters to which the precipitation process is most vulnerable, so that such parameters may be controlled effectively. Besides, the effect and the importance of equilibrium conditions during the precipitation process, on the quality of the final ADU, was also established. The paper presents the results of these studies. (author). 6 refs., 3 figs., 7 tabs

  18. Precipitation Reconstruction (PREC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The PREC data set is an analysis of monthly precipitation constructed on a 2.5(o)lat/lon grid over the global for the period from 1948 to the present. The land...

  19. Harmonic analysis of the precipitation in Greece

    Science.gov (United States)

    Nastos, P. T.; Zerefos, C. S.

    2009-04-01

    Greece is a country with a big variety of climates due to its geographical position, to the many mountain ranges and also to the multifarious and long coastline. The mountainous volumes are of such orientation that influences the distribution of the precipitation, having as a result, Western Greece to present great differentiations from Central and Eastern Greece. The application of harmonic analysis to the annual variability of precipitation is the goal of this study, so that the components, which compose the annual variability, be elicited. For this purpose, the mean monthly precipitation data from 30 meteorological stations of National Meteorological Service were used for the time period 1950-2000. The initial target is to reduce the number of variables and to detect structure in the relationships between variables. The most commonly used technique for this purpose is the application of Factor Analysis to a table having as columns the meteorological stations-variables and rows the monthly mean precipitation, so that 2 main factors were calculated, which explain the 98% of total variability of precipitation in Greece. Factor 1, representing the so-called uniform field and interpreting the most of the total variance, refers in fact to the Mediterranean depressions, affecting mainly the West of Greece and also the East Aegean and the Asia Minor coasts. In the process, the Fourier Analysis was applied to the factor scores extracted from the Factor Analysis, so that 2 harmonic components are resulted, which explain above the 98% of the total variability of each main factor, and are due to different synoptic and thermodynamic processes associated with Greece's precipitation construction. Finally, the calculation of the time of occurrence of the maximum precipitation, for each harmonic component of each one of the two main factors, gives the spatial distribution of appearance of the maximum precipitation in the Hellenic region.

  20. Impact of Precipitation Fluctuation on Desert-Grassland ANPP

    Directory of Open Access Journals (Sweden)

    Liangxu Liu

    2016-11-01

    Full Text Available Precipitation change has significantly influenced annual net primary productivity (ANPP at either annual or seasonal scales in desert steppes in arid and semi-arid regions. In order to reveal the process of precipitation driving ANPP at different time scales, responses of different ANPP levels to the inter-annual and intra-annual precipitation fluctuations were analyzed. ANPP was reversed by building a ground reflectance spectrum model, from 2000 to 2015, using the normalized differential vegetation index of the Moderate-Resolution Imaging Spectroradiometer (MODIS-NDVI data at 250 m × 250 m spatial resolution. Since the description of the differently expressing forms of precipitation are not sufficient in former studies in order to overcome the deficiency of former studies, in this study, intra-annual precipitation fluctuations were analyzed not only with precipitation of May–August, June–August, July–August, and August, respectively, which have direct influence on vegetation productivity within the year, but quantitative description, vector precipitation (R, concentration ratio (Cd, and concentration period (D, were also used to describe the overall characteristics of intra-annual precipitation fluctuations. The concentration ratio and the maximum precipitation period of the intra-annual precipitation were represented by using monthly precipitation. The results showed that: (1 in the period from 1971 to 2015, the maximum annual precipitation is 3.76 times that of the minimum in the Urat desert steppe; (2 vector precipitation is more significantly related to ANPP (r = 0.7724, p = 0.000 compared to meteorological annual precipitation and real annual precipitation influence; and (3 annual precipitation is almost concentrated in 5–8 months and monthly precipitation accumulation has significantly effected ANPP, especially in the period of June–August, since the vegetation composition in the study area was mainly sub-shrubs and perennial

  1. Investigation of Relationship Between Hydrologic Processes of Precipitation, Evaporation and Stream Flow Using Linear Time Series Models (Case study: Western Basins of Lake Urmia)

    OpenAIRE

    M. Moravej; K. Khalili; J. Behmanesh

    2016-01-01

    Introduction: Studying the hydrological cycle, especially in large scales such as water catchments, is difficult and complicated despite the fact that the numbers of hydrological components are limited. This complexity rises from complex interactions between hydrological components and environment. Recognition, determination and modeling of all interactive processes are needed to address this issue, but it's not feasible for dealing with practical engineering problems. So, it is more convenie...

  2. Recent and future extreme precipitation over Ukraine

    Science.gov (United States)

    Vyshkvarkova, Olena; Voskresenskaya, Elena

    2014-05-01

    The aim of study is to analyze the parameters of precipitation extremes and inequality over Ukraine in recent climate epoch and their possible changes in the future. Data of observations from 28 hydrometeorological stations over Ukraine and output of GFDL-CM3 model (CMIP5) for XXI century were used in the study. The methods of concentration index (J. Martin-Vide, 2004) for the study of precipitation inequality while the extreme precipitation indices recommended by the ETCCDI - for the frequency of events. Results. Precipitation inequality on the annual and seasonal scales was studied using estimated CI series for 1951-2005. It was found that annual CI ranges vary from 0.58 to 0.64. They increase southward from the north-west (forest zone) and the north-east (forest steppe zone) of Ukraine. CI maxima are located in the coastal regions of the Black Sea and the Sea of Azov. Annual CI spatial distribution indicates that the contribution of extreme precipitation into annual totals is most significant at the boundary zone between steppe and marine regions. At the same time precipitation pattern at the foothill of Carpathian Mountains is more homogenous. The CI minima (0.54) are typical for the winter season in foothill of Ukrainian Carpathians. The CI maxima reach 0.71 in spring at the steppe zone closed to the Black Sea coast. It should be noted that the greatest ranges of CI maximum and CI minimum deviation are typical for spring. It is associated with patterns of cyclone trajectories in that season. The most territory is characterized by tendency to decrease the contribution of extreme precipitation into the total amount (CI linear trends are predominantly negative in all seasons). Decadal and interdecadal variability of precipitation inequality associated with global processes in ocean-atmosphere system are also studied. It was shown that precipitation inequality over Ukraine on 10 - 15 % stronger in negative phase of Pacific Decadal Oscillation and in positive phase

  3. Mechanisms affecting swelling in alloys with precipitates

    International Nuclear Information System (INIS)

    Mansur, L.K.; Haynes, M.R.; Lee, E.H.

    1980-01-01

    In alloys under irradiation many mechanisms exist that couple phase instability to cavity swelling. These are compounded with the more familiar mechanisms associated with point defect behavior and the evolution of microstructure. The mechanisms may be classified according to three modes of operation. Some affect cavity swelling directly by cavity-precipitate particle association, others operate indirectly by precipitate-induced changes in sinks other than cavities and finally there are mechanisms that are mediated by precipitate-induced changes in the host matrix. The physics of one mechanism of each type is developed in detail and the results compared where possible to experimental measurements. In particular, we develop the theory necessary to treat the effects on swelling of precipitation-induced changes in overall sink density; precipitation-induced changes in point defect trapping by solute depletion and creation of precipitate particle-matrix interfacial trap sites; and preciwill come from waste wood available locally requiring minimal energy for recovery and transportation to the site. The applicant is strongly considering the use of a solar preheating unit anium southward as well as to deeper dened al half-lives with experimental ones, over a range of 24 orders of magnitude was obtained. This is a strong argument that the alpha decay could be considered a fission process with very high mass asymmetry and charge density asymmetry

  4. Acidity of Scandinavian precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Barrett, E; Bordin, G

    1955-01-01

    Data on the pH of the total monthly precipitation at stations of a Swedish network for sampling and chemical analysis of precipitation and atmospheric aerosols during the year July 1953 to June 1954 are presented and discussed, together with the pH data from the first two months of operation of a large pan-Scandinavian net. It is found that well-defined regions of acidity and alkalinity relative to the pH of water in equilibrium with atmospheric carbon dioxide exist, and that these regions persist to such an extent that the monthly deviations from the pattern of the annual mean pH at stations unaffected by local pollution show persistently high acidity, while inland northern stations show equally persistent alkalinity. Some possible reasons for the observed distributions are considered.

  5. "Cool" vs. "warm" winter precipitation and its effect on streamflow in California

    OpenAIRE

    Cayan, Daniel R.

    1991-01-01

    Precipitation is a difficult variable to understand and predict. In this study, monthly precipitation in California is divided into two classes according to the monthly temperature to better diagnose the atmospheric circulation that causes precipitation, and to illustrate how temperature compounds the precipitation to runoff process.

  6. Micro and colloidal stickie pacification with precipitated calcium carbonate

    Science.gov (United States)

    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...

  7. Model simulations of aerosol effects on clouds and precipitation in comparison with ARM data

    Energy Technology Data Exchange (ETDEWEB)

    Penner, Joyce E. [Univ. of Michigan, Ann Arbor, MI (United States); Zhou, Cheng [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-01-12

    Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 05/27/2011 at the Southern Great Plains (SGP) measurement site established by Department of Energy's Atmospheric Radiation Measurement (ARM) Program using a single column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP in CAM is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near cloud top, resulting in an overall decrease in LWP. Our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations.

  8. Generation of a stochastic precipitation model for the tropical climate

    Science.gov (United States)

    Ng, Jing Lin; Abd Aziz, Samsuzana; Huang, Yuk Feng; Wayayok, Aimrun; Rowshon, MK

    2017-06-01

    A tropical country like Malaysia is characterized by intense localized precipitation with temperatures remaining relatively constant throughout the year. A stochastic modeling of precipitation in the flood-prone Kelantan River Basin is particularly challenging due to the high intermittency of precipitation events of the northeast monsoons. There is an urgent need to have long series of precipitation in modeling the hydrological responses. A single-site stochastic precipitation model that includes precipitation occurrence and an intensity model was developed, calibrated, and validated for the Kelantan River Basin. The simulation process was carried out separately for each station without considering the spatial correlation of precipitation. The Markov chains up to the fifth-order and six distributions were considered. The daily precipitation data of 17 rainfall stations for the study period of 1954-2013 were selected. The results suggested that second- and third-order Markov chains were suitable for simulating monthly and yearly precipitation occurrences, respectively. The fifth-order Markov chain resulted in overestimation of precipitation occurrences. For the mean, distribution, and standard deviation of precipitation amounts, the exponential, gamma, log-normal, skew normal, mixed exponential, and generalized Pareto distributions performed superiorly. However, for the extremes of precipitation, the exponential and log-normal distributions were better while the skew normal and generalized Pareto distributions tend to show underestimations. The log-normal distribution was chosen as the best distribution to simulate precipitation amounts. Overall, the stochastic precipitation model developed is considered a convenient tool to simulate the characteristics of precipitation in the Kelantan River Basin.

  9. Deeply subducted continental fragments - Part 1: Fracturing, dissolution-precipitation, and diffusion processes recorded by garnet textures of the central Sesia Zone (western Italian Alps)

    Science.gov (United States)

    Giuntoli, Francesco; Lanari, Pierre; Engi, Martin

    2018-02-01

    Contiguous continental high-pressure terranes in orogens offer insight into deep recycling and transformation processes that occur in subduction zones. These remain poorly understood, and currently debated ideas need testing. The approach we chose is to investigate, in detail, the record in suitable rock samples that preserve textures and robust mineral assemblages that withstood overprinting during exhumation. We document complex garnet zoning in eclogitic mica schists from the Sesia Zone (western Italian Alps). These retain evidence of two orogenic cycles and provide detailed insight into resorption, growth, and diffusion processes induced by fluid pulses in high-pressure conditions. We analysed local textures and garnet compositional patterns, which turned out remarkably complex. By combining these with thermodynamic modelling, we could unravel and quantify repeated fluid-rock interaction processes. Garnet shows low-Ca porphyroclastic cores that were stable under (Permian) granulite facies conditions. The series of rims that surround these cores provide insight into the subsequent evolution: the first garnet rim that surrounds the pre-Alpine granulite facies core in one sample indicates that pre-Alpine amphibolite facies metamorphism followed the granulite facies event. In all samples documented, cores show lobate edges and preserve inner fractures, which are sealed by high-Ca garnet that reflects high-pressure Alpine conditions. These observations suggest that during early stages of subduction, before hydration of the granulites, brittle failure of garnet occurred, indicating high strain rates that may be due to seismic failure. Several Alpine rims show conspicuous textures indicative of interaction with hydrous fluid: (a) resorption-dominated textures produced lobate edges, at the expense of the outer part of the granulite core; (b) peninsulas and atoll garnet are the result of replacement reactions; and (c) spatially limited resorption and enhanced transport

  10. Elimination of ammonium from waste water by means of chemical precipitation. Summary

    International Nuclear Information System (INIS)

    Boehnke, B.; Schulze-Rettmer, R.

    1990-07-01

    In the course of this research project, a process for precipitating ammonium salts contained in waste water was developed. The precipitate can be used as fertilizer. The purification process was tested in a pilot plant. (EF) [de

  11. Precipitation in partially stabilized zirconia

    International Nuclear Information System (INIS)

    Bansal, G.K.

    1975-01-01

    Transmission electron microscopy was used to study the substructure of partially stabilized ZrO 2 (PSZ) samples, i.e., 2-phase systems containing both cubic and monoclinic modifications of zirconia, after various heat treatments. Monoclinic ZrO 2 exists as (1) isolated grains within the polycrystalline aggregate (a grain- boundary phase) and (2) small plate-like particles within cubic grains. These intragranular precipitates are believed to contribute to the useful properties of PSZ via a form of precipitation hardening. These precipitates initially form as tetragonal ZrO 2 , with a habit plane parallel to the brace 100 brace matrix planes. The orientation relations between the tetragonal precipitates and the cubic matrix are brace 100 brace/sub matrix/ 2 parallel brace 100 brace /sub precipitate/ or (001)/sub precipitate/ and broken bracket 100 broken bracket/sub matrix/ 2 parallel broken bracket 100 broken bracket/sub precipitate/ or [001]/sub precipitate/. (U.S.)

  12. Hourly Precipitation Data (HPD) Publication

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Hourly Precipitation Data (HPD) Publication is archived and available from the National Climatic Data Center (NCDC). This publication contains hourly precipitation...

  13. Precipitation of metal nitrides from chloride melts

    International Nuclear Information System (INIS)

    Slater, S.A.; Miller, W.E.; Willit, J.L.

    1996-01-01

    Precipitation of actinides, lanthanides, and fission products as nitrides from molten chloride melts is being investigated for use as a final cleanup step in treating radioactive salt wastes generated by electrometallurgical processing of spent nuclear fuel. The radioactive components (eg, fission products) need to be removed to reduce the volume of high-level waste that requires disposal. To extract the fission products from the salt, a nitride precipitation process is being developed. The salt waste is first contacted with a molten metal; after equilibrium is reached, a nitride is added to the metal phase. The insoluble nitrides can be recovered and converted to a borosilicate glass after air oxidation. For a bench-scale experimental setup, a crucible was designed to contact the salt and metal phases. Solubility tests were performed with candidate nitrides and metal nitrides for which there are no solubility data. Experiments were performed to assess feasibility of precipitation of metal nitrides from chloride melts

  14. Precipitation from Space: Advancing Earth System Science

    Science.gov (United States)

    Kucera, Paul A.; Ebert, Elizabeth E.; Turk, F. Joseph; Levizzani, Vicenzo; Kirschbaum, Dalia; Tapiador, Francisco J.; Loew, Alexander; Borsche, M.

    2012-01-01

    Of the three primary sources of spatially contiguous precipitation observations (surface networks, ground-based radar, and satellite-based radar/radiometers), only the last is a viable source over ocean and much of the Earth's land. As recently as 15 years ago, users needing quantitative detail of precipitation on anything under a monthly time scale relied upon products derived from geostationary satellite thermal infrared (IR) indices. The Special Sensor Microwave Imager (SSMI) passive microwave (PMW) imagers originated in 1987 and continue today with the SSMI sounder (SSMIS) sensor. The fortunate longevity of the joint National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA) Tropical Rainfall Measuring Mission (TRMM) is providing the environmental science community a nearly unbroken data record (as of April 2012, over 14 years) of tropical and sub-tropical precipitation processes. TRMM was originally conceived in the mid-1980s as a climate mission with relatively modest goals, including monthly averaged precipitation. TRMM data were quickly exploited for model data assimilation and, beginning in 1999 with the availability of near real time data, for tropical cyclone warnings. To overcome the intermittently spaced revisit from these and other low Earth-orbiting satellites, many methods to merge PMW-based precipitation data and geostationary satellite observations have been developed, such as the TRMM Multisatellite Precipitation Product and the Climate Prediction Center (CPC) morphing method (CMORPH. The purpose of this article is not to provide a survey or assessment of these and other satellite-based precipitation datasets, which are well summarized in several recent articles. Rather, the intent is to demonstrate how the availability and continuity of satellite-based precipitation data records is transforming the ways that scientific and societal issues related to precipitation are addressed, in ways that would not be

  15. Study of calcium carbonate and sulfate co-precipitation

    KAUST Repository

    Zarga, Y.

    2013-06-01

    Co-precipitation of mineral based salts in scaling is still not well understood and/or thermodynamically well defined in the water industry. This study focuses on investigating calcium carbonate (CaCO3) and sulfate mixed precipitation in scaling which is commonly observed in industrial water treatment processes including seawater desalination either by thermal-based or membrane-based processes. Co-precipitation kinetics were studied carefully by monitoring several parameters simultaneously measured, including: pH, calcium and alkalinity concentrations as well as quartz microbalance responses. The CaCO3 germination in mixed precipitation was found to be different than that of simple precipitation. Indeed, the co-precipitation of CaCO3 germination time was not anymore related to supersaturation as in a simple homogenous precipitation, but was significantly reduced when the gypsum crystals appeared first. On the other hand, the calcium sulfate crystals appear to reduce the energetic barrier of CaCO3 nucleation and lead to its precipitation by activating heterogeneous germination. However, the presence of CaCO3 crystals does not seem to have any significant effect on gypsum precipitation. IR spectroscopy and the Scanning Electronic Microscopy (SEM) were used to identify the nature of scales structures. Gypsum was found to be the dominant precipitate while calcite and especially vaterite were found at lower proportions. These analyses showed also that gypsum crystals promote calcite crystallization to the detriment of other forms. © 2013 Elsevier Ltd.

  16. Precipitation Indices Low Countries

    Science.gov (United States)

    van Engelen, A. F. V.; Ynsen, F.; Buisman, J.; van der Schrier, G.

    2009-09-01

    Since 1995, KNMI published a series of books(1), presenting an annual reconstruction of weather and climate in the Low Countries, covering the period AD 763-present, or roughly, the last millennium. The reconstructions are based on the interpretation of documentary sources predominantly and comparison with other proxies and instrumental observations. The series also comprises a number of classifications. Amongst them annual classifications for winter and summer temperature and for winter and summer dryness-wetness. The classification of temperature have been reworked into peer reviewed (2) series (AD 1000-present) of seasonal temperatures and temperature indices, the so called LCT (Low Countries Temperature) series, now incorporated in the Millennium databases. Recently we started a study to convert the dryness-wetness classifications into a series of precipitation; the so called LCP (Low Countries Precipitation) series. A brief outline is given here of the applied methodology and preliminary results. The WMO definition for meteorological drought has been followed being that a period is called wet respectively dry when the amount of precipitation is considerable more respectively less than usual (normal). To gain a more quantitative insight for four locations, geographically spread over the Low Countries area (De Bilt, Vlissingen, Maastricht and Uccle), we analysed the statistics of daily precipitation series, covering the period 1900-present. This brought us to the following definition, valid for the Low Countries: A period is considered as (very) dry respectively (very) wet if over a continuous period of at least 60 days (~two months) cq 90 days (~three months) on at least two out of the four locations 50% less resp. 50% more than the normal amount for the location (based on the 1961-1990 normal period) has been measured. This results into the following classification into five drought classes hat could be applied to non instrumental observations: Very wet period

  17. The Passive Microwave Neural Network Precipitation Retrieval (PNPR) for AMSU/MHS and ATMS cross-track scanning radiometers

    Science.gov (United States)

    Sano', Paolo; Casella, Daniele; Panegrossi, Giulia; Cinzia Marra, Anna; Dietrich, Stefano

    2016-04-01

    Spaceborne microwave cross-track scanning radiometers, originally developed for temperature and humidity sounding, have shown great capabilities to provide a significant contribution in precipitation monitoring both in terms of measurement quality and spatial/temporal coverage. The Passive microwave Neural network Precipitation Retrieval (PNPR) algorithm for cross-track scanning radiometers, originally developed for the Advanced Microwave Sounding Unit/Microwave Humidity Sounder (AMSU-A/MHS) radiometers (on board the European MetOp and U.S. NOAA satellites), was recently newly designed to exploit the Advanced Technology Microwave Sounder (ATMS) on board the Suomi-NPP satellite and the future JPSS satellites. The PNPR algorithm is based on the Artificial Neural Network (ANN) approach. The main PNPR-ATMS algorithm changes with respect to PNPR-AMSU/MHS are the design and implementation of a new ANN able to manage the information derived from the additional ATMS channels (respect to the AMSU-A/MHS radiometer) and a new screening procedure for not-precipitating pixels. In order to achieve maximum consistency of the retrieved surface precipitation, both PNPR algorithms are based on the same physical foundation. The PNPR is optimized for the European and the African area. The neural network was trained using a cloud-radiation database built upon 94 cloud-resolving simulations over Europe and the Mediterranean and over the African area and radiative transfer model simulations of TB vectors consistent with the AMSU-A/MHS and ATMS channel frequencies, viewing angles, and view-angle dependent IFOV sizes along the scan projections. As opposed to other ANN precipitation retrieval algorithms, PNPR uses a unique ANN that retrieves the surface precipitation rate for all types of surface backgrounds represented in the training database, i.e., land (vegetated or arid), ocean, snow/ice or coast. This approach prevents different precipitation estimates from being inconsistent with one

  18. Precipitates and boundaries interaction in ferritic ODS steels

    Energy Technology Data Exchange (ETDEWEB)

    Sallez, Nicolas, E-mail: nicolas.sallez@simap.grenoble-inp.fr [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); Hatzoglou, Constantinos [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Normandie Université (France); Delabrouille, Fredéric [EDF–EDF R& D, Les Renardières, 77818 Moret-sur-Loing (France); Sornin, Denis; Chaffron, Laurent [CEA, DEN, Service de Recherches Métallurgiques Appliqué, 91191 Gif-sur-Yvette (France); Blat-Yrieix, Martine [EDF–EDF R& D, Les Renardières, 77818 Moret-sur-Loing (France); Radiguet, Bertrand; Pareige, Philippe [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Normandie Université (France); Donnadieu, Patricia; Bréchet, Yves [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France)

    2016-04-15

    In the course of a recrystallization study of Oxide Dispersion Strengthened (ODS) ferritic steels during extrusion, particular interest was paid to the (GB) Grain Boundaries interaction with precipitates. Complementary and corresponding characterization experiments using Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX) and Atom Probe Tomography (APT) have been carried out on a voluntarily interrupted extrusion or extruded samples. Microscopic observations of Precipitate Free Zones (PFZ) and precipitates alignments suggest precipitate interaction with migrating GB involving dissolution and Oswald ripening of the precipitates. This is consistent with the local chemical information gathered by EDX and APT. This original mechanism for ODS steels is similar to what had been proposed in the late 80s for similar observation made on Ti alloys reinforced by nanosized yttrium oxides: An interaction mechanism between grain boundaries and precipitates involving a diffusion controlled process of precipitates dissolution at grain boundaries. It is believed that this mechanism can be of primary importance to explain the mechanical behaviour of such steels. - Highlights: • To study the microstructural evolution of a ferritic ODS steel during its extrusion, observations have been carried on samples resulting from a voluntarily interrupted extrusion and extruded materials. • A highly heterogeneous precipitate population have been observed. Nanosized coherent precipitates (2–5 nm) on both sides of the grain boundaries despite grain boundary migration after precipitation due to further thermo-mechanical processing as well as coarse precipitates (10–40 nm) alignments are observed on the grain boundaries and within the grains, parallel to the grain boundaries. • Asymmetrical PFZs can be observed around precipitates alignments and grain boundaries. Using TEM with EDX and APT we have been able to ensure that the PFZs are chemically depleted.

  19. Asphaltene precipitates in oil production wells

    DEFF Research Database (Denmark)

    Kleinitz, W,; Andersen, Simon Ivar

    1998-01-01

    compounds in the organic scales from operations definitely differed from the data published in the literature. In order to dissolve the precipitates and thus eliminate the damage, various organic solvents and industrial solvent mixtures were examined. The kinetics of the dissolution process in operational...... production is also explained and discussed in detail from a reservoir engineering standpoint....

  20. Modelling the operation of precipitator with vortex effect

    International Nuclear Information System (INIS)

    Eysseric-Emile, C.

    1994-01-01

    In the Purex process which is implemented for the processing of irradiated fuels to eliminate fission products and to recover and valorise uranium and plutonium under the form of end products, a precipitation operation occurs to prepare the plutonium oxalate. This research thesis aims at analysing hydrodynamic characteristics of a specific apparatus used for this precipitation, the precipitator with vortex effect. In a first part, the author presents the problems associated with precipitation operations, their implementation in the processing of irradiated fuels, and compares the considered precipitator with other devices used for the precipitation of radioactive compounds. He proposes a review of literature on the vortex effect in agitated vessel, highlights the key parameter (the forced vortex radius), and reports some preliminary measurements performed on the precipitator. The author then reports the study of liquid phase flows in the precipitator, measurements of rate of suspension, and the study of micro-mixing with reactants. He finally reports attempts to validate trends noticed during flow analysis and a first simple modelling of the precipitator [fr

  1. Study of aluminum nitride precipitation in Fe- 3%Si steel

    Directory of Open Access Journals (Sweden)

    F.L. Alcântara

    2013-01-01

    Full Text Available For good performance of electrical steels it is necessary a high magnetic induction and a low power loss when submitted to cyclic magnetization. A fine dispersion of precipitates is a key requirement in the manufacturing process of Fe- 3%Si grain oriented electrical steel. In the production of high permeability grain oriented steel precipitate particles of copper and manganese sulphides and aluminium nitride delay normal grain growth during primary recrystallization, causing preferential growth of grains with Goss orientation during secondary recrystallization. The sulphides precipitate during the hot rolling process. The aluminium nitride particles are formed during hot rolling and the hot band annealing process. In this work AlN precipitation during hot deformation of a high permeability grain oriented 3%Si steel is examined. In the study, transfer bar samples were submitted to controlled heating, compression and cooling treatments in order to simulate a reversible hot rolling finishing. The samples were analyzed using the transmission electron microscope (TEM in order to identify the precipitates and characterize size distribution. Precipitate extraction by dissolution method and analyses by inductively coupled plasma optical emission spectrometry (ICP-OES were used to quantify the precipitation. The results allowed to describe the precipitation kinetics by a precipitation-time-temperature (PTT diagram for AlN formation during hot rolling.

  2. A novel electrostatic precipitator

    International Nuclear Information System (INIS)

    Tang, Minkang; Wang, Liqian; Lin, Zhigui

    2013-01-01

    ESP (Electrostatic Precipitation) has been widely used in the mining, building materials, metallurgy and power industries. Dust particles or other harmful particles from the airstream can be precipitated by ESP with great collecting efficiency. Because of its' large size, high cost and energy consumption, the scope of application of ESP has been limited to a certain extent. By means of the theory of electrostatics and fluid dynamics, a corona assembly with a self-cleaning function and a threshold voltage automatic tracking technology has been developed and used in ESP. It is indicated that compared with conventional ESP, the electric field length has been reduced to 1/10 of the original, the current density on the collecting electrode increased 3-5 times at the maximum, the approach speed of dust particles in the electric field towards the collecting electrode is 4 times that in conventional ESP and the electric field wind speed may be enhanced by 2-3 times the original. Under the premise of ESP having a high efficiency of dust removal, equipment volume may be actually reduced to 1/5 to 1/10 of the original volume and energy consumption may be reduced by more than 50%.

  3. The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset

    Science.gov (United States)

    Huffman, George J.; Adler, Robert F.; Arkin, Philip; Chang, Alfred; Ferraro, Ralph; Gruber, Arnold; Janowiak, John; McNab, Alan; Rudolf, Bruno; Schneider, Udo

    1997-01-01

    The Global Precipitation Climatology Project (GPCP) has released the GPCP Version 1 Combined Precipitation Data Set, a global, monthly precipitation dataset covering the period July 1987 through December 1995. The primary product in the dataset is a merged analysis incorporating precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit -satellite infrared data, and rain gauge observations. The dataset also contains the individual input fields, a combination of the microwave and infrared satellite estimates, and error estimates for each field. The data are provided on 2.5 deg x 2.5 deg latitude-longitude global grids. Preliminary analyses show general agreement with prior studies of global precipitation and extends prior studies of El Nino-Southern Oscillation precipitation patterns. At the regional scale there are systematic differences with standard climatologies.

  4. Properties of precipitates formed during ammonization of extractional phosphoric acid

    International Nuclear Information System (INIS)

    Zakharova, B.S.; Komissarova, L.N.; Naumov, S.V.; Traskin, V.Yu.

    1992-01-01

    Dimensions of precipitated rare-earth phosphate particles -(0.1 μm)- are near the boundary of colloidal system sedimentation stability range at neutralization of extraction phosphoric acid. Thus, formation of multiple aggregates of colloidal particles results in immediate sedimentation of the precipitate. Processes occurring within the system may be described using second order reaction equation. Average efficient size of precipitates grows at reduction of reaction mixture pH. About 30% of rare-earth elements and yttrium in the extraction phosphoric acid is extracted from it; concentration of rare-earth elements, yttrium and scandium in precipitate is maximum 2 mass. %

  5. Optimization of precipitation conditions of thorium oxalate precipitate

    International Nuclear Information System (INIS)

    Pazukhin, Eh.M.; Smirnova, E.A.; Krivokhatskij, A.S.; Pazukhina, Yu.L.; Kiselev, P.P.

    1986-01-01

    Thorium precipitation in the form of difficultly soluble oxalate has been investigated. The equation binding the concentration of metal with the nitric acid in the initial solution and quantity of a precipitator necessary for minimization of desired product losses is derived. The graphical solution of this equation for a case, when the oxalic acid with 0.78 mol/l concentration is the precipitator, is presented

  6. Precipitated iron. A limit on gettering efficacy in multicrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Fenning, D.P.; Hofstetter, J.; Bertoni, M.I.; Buonassisi, T. [Massachusetts Institute of Technology MIT, Cambridge, Massachusetts 02139 (United States); Coletti, G. [ECN Solar Energy, Westerduinweg 3, NL-1755 LE Petten (Netherlands); Lai, B. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Del Canizo, C. [Instituto de Energia Solar, Universidad Politecnica de Madrid, 28040 Madrid (Spain)

    2013-01-31

    A phosphorus diffusion gettering model is used to examine the efficacy of a standard gettering process on interstitial and precipitated iron in multicrystalline silicon. The model predicts a large concentration of precipitated iron remaining after standard gettering for most as-grown iron distributions. Although changes in the precipitated iron distribution are predicted to be small, the simulated post-processing interstitial iron concentration is predicted to depend strongly on the as-grown distribution of precipitates, indicating that precipitates must be considered as internal sources of contamination during processing. To inform and validate the model, the iron distributions before and after a standard phosphorus diffusion step are studied in samples from the bottom, middle, and top of an intentionally Fe-contaminated laboratory ingot. A census of iron-silicide precipitates taken by synchrotron-based X-ray fluorescence microscopy confirms the presence of a high density of iron-silicide precipitates both before and after phosphorus diffusion. A comparable precipitated iron distribution was measured in a sister wafer after hydrogenation during a firing step. The similar distributions of precipitated iron seen after each step in the solar cell process confirm that the effect of standard gettering on precipitated iron is strongly limited as predicted by simulation. Good agreement between the experimental and simulated data supports the hypothesis that gettering kinetics is governed by not only the total iron concentration but also by the distribution of precipitated iron. Finally, future directions based on the modeling are suggested for the improvement of effective minority carrier lifetime in multicrystalline silicon solar cells.

  7. A Thermodynamic Mixed-Solid Asphaltene Precipitation Model

    DEFF Research Database (Denmark)

    Lindeloff, Niels; Heidemann, R.A.; Andersen, Simon Ivar

    1998-01-01

    A simple model for the prediction of asphaltene precipitation is proposed. The model is based on an equation of state and uses standard thermodynamics, thus assuming that the precipitation phenomenon is a reversible process. The solid phase is treated as an ideal multicomponent mixture. An activity...

  8. Electro-precipitation of magnetite nanoparticles: an electrochemical study

    OpenAIRE

    Ibrahim, Mona; Groenen-Serrano, Karine; Noé, Laure; Garcia, Cécile; Verelst, Marc

    2009-01-01

    Nanoparticles of magnetites (Fe3O4) are synthesized with a new process based on electro-precipitation in ethanol medium. A mechanism pathway is proposed consisting of a Fe(OH)3 precipitation followed by the reduction of iron hydroxide to magnetite in the presence of hydroxyl ions which are enerated at the cathode.

  9. Stable Isotopic Variations in Precipitation in Southwest China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This study analyzes the relationships of stable isotopes in precipitation with temperature, air pressure and humidity at different altitudes, and the potential influencing mechanisms of control factors on the stable isotopes in precipitation in Southwest China. There appear marked negative correlations of the δ18O in precipitation with precipitation amount, vapor pressure and atmospheric precipitable water (PW)at the Mengzi, Simao and Tengchong stations on the synoptic timescale; the marked negative correlations between the δ18O in precipitation and the diurnal mean temperature at 400 hPa, 500 hPa, 700 hPa and 850hPa are different from the temperature effect in middle-high-latitude inland areas. In addition, the notable positive correlation between the δ18O in precipitation and the dew-point deficit △Td at different altitudes is found at the three stations. Precipitation is not the only factor generating an amount effect. Probably,the amount effect is related to the variations of atmospheric circulation and vapor origins. On the annual timescale, the annual precipitation amount weighted-mean δ18O displays negative correlations not only with annual precipitation but also with annual mean temperature at 500 hPa. It can be deduced that, in the years with an abnormally strong summer monsoon, more warm and wet air from low-latitude oceans is transported northward along the vapor channel located in Southwest China and generates abnormally strong rainfall on the way. Meanwhile, the abnormally strong condensation process will release more condensed latent heat in the atmosphere, and this will lead to a rise of atmospheric temperature during rainfall but a decline of δ18O in the precipitation. On the other hand, in the years with an abnormally weak summer monsoon, the precipitation and the atmospheric temperature during rainfalls decrease abnormally but the δ18O in precipitation increases.

  10. Acid precipitation literature review

    Energy Technology Data Exchange (ETDEWEB)

    Seip, H M; Andersen, B; Andersson, G; Hov, Oe; Kucera, V; Moseholm, L

    1986-01-01

    There is an increasing number of publications on acid deposition and related phenomena. Interest in these topics has also been reflected in a considerable number of meetings and conferences in this field. The largest of these in 1985 was the ''International Symposium on Acidic Precipitation'' (Muskoka, Ontario). Most work so far has been carried out in North America and Europe. There is, however, an increasing interest in obtaining a better picture of sensitive areas and possible acidification in other parts of the world. Anthropogenic SO/sub 2/ emissions have been estimated to be (in TgSyr/sup -1/): 2.4 (Africa), 4.1 (South America), 0.7 (Ocenia), and 18.3 (Asia). The largest increase during the last decade has been in Asia. Based on Studies of precipitation in remote areas it has been suggested that the natural background concentration for sulphate in many areas should be about 6 ..mu..eq 1/sup -1/. A new study of sulphate and nitrate in Greenland snow showed that both ions increased by a factor of about 2 from 1895 to 1978. The concentrations of SO/sub 2/ at Norwegian rural sites show a decreasing trend since late 1970s, while concentrations of sulphate in air show no clear trend. More reliable models for transformation, transport and deposition of chemicals are being developed, including three-dimensional grid models to describe episodes of elevated pollution levels lasting for a few days. Model calculations indicate that control of hydrocarbon (HC) emissions is much more efficient in reducing the ozone level in southern Scandinavia in episodes influenced by long-range transported pollutants than NO/sub x/ control of combined NO/sub x/ and HC control. 36 refs. (EG).

  11. Comparing NEXRAD Operational Precipitation Estimates and Raingage Observations of Intense Precipitation in the Missouri River Basin.

    Science.gov (United States)

    Young, C. B.

    2002-05-01

    Accurate observation of precipitation is critical to the study and modeling of land surface hydrologic processes. NEXRAD radar-based precipitation estimates are increasingly used in field experiments, hydrologic modeling, and water and energy budget studies due to their high spatial and temporal resolution, national coverage, and perceived accuracy. Extensive development and testing of NEXRAD precipitation algorithms have been carried out in the Southern Plains. Previous studies (Young et al. 2000, Young et al. 1999, Smith et al. 1996) indicate that NEXRAD operational products tend to underestimate precipitation at light rain rates. This study investigates the performance of NEXRAD precipitation estimates of high-intensity rainfall, focusing on flood-producing storms in the Missouri River Basin. NEXRAD estimates for these storms are compared with data from multiple raingage networks, including NWS recording and non-recording gages and ALERT raingage data for the Kansas City metropolitan area. Analyses include comparisons of gage and radar data at a wide range of temporal and spatial scales. Particular attention is paid to the October 4th, 1998, storm that produced severe flooding in Kansas City. NOTE: The phrase `NEXRAD operational products' in this abstract includes precipitation estimates generated using the Stage III and P1 algorithms. Both of these products estimate hourly accumulations on the (approximately) 4 km HRAP grid.

  12. On the complex conductivity signatures of calcite precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuxin; Hubbard, Susan; Williams, Kenneth Hurst; Ajo-Franklin, Jonathan

    2009-11-01

    Calcite is a mineral phase that frequently precipitates during subsurface remediation or geotechnical engineering processes. This precipitation can lead to changes in the overall behavior of the system, such as flow alternation and soil strengthening. Because induced calcite precipitation is typically quite variable in space and time, monitoring its distribution in the subsurface is a challenge. In this research, we conducted a laboratory column experiment to investigate the potential of complex conductivity as a mean to remotely monitor calcite precipitation. Calcite precipitation was induced in a glass bead (3 mm) packed column through abiotic mixing of CaCl{sub 2} and Na{sub 2}CO{sub 3} solutions. The experiment continued for 12 days with a constant precipitation rate of {approx}0.6 milimole/d. Visual observations and scanning electron microscopy imaging revealed two distinct phases of precipitation: an earlier phase dominated by well distributed, discrete precipitates and a later phase characterized by localized precipitate aggregation and associated pore clogging. Complex conductivity measurements exhibited polarization signals that were characteristic of both phases of calcite precipitation, with the precipitation volume and crystal size controlling the overall polarization magnitude and relaxation time constant. We attribute the observed responses to polarization at the electrical double layer surrounding calcite crystals. Our experiment illustrates the potential of electrical methods for characterizing the distribution and aggregation state of nonconductive minerals like calcite. Advancing our ability to quantify geochemical transformations using such noninvasive methods is expected to facilitate our understanding of complex processes associated with natural subsurface systems as well as processes induced through engineered treatments (such as environmental remediation and carbon sequestration).

  13. Scaling and clustering effects of extreme precipitation distributions

    Science.gov (United States)

    Zhang, Qiang; Zhou, Yu; Singh, Vijay P.; Li, Jianfeng

    2012-08-01

    SummaryOne of the impacts of climate change and human activities on the hydrological cycle is the change in the precipitation structure. Closely related to the precipitation structure are two characteristics: the volume (m) of wet periods (WPs) and the time interval between WPs or waiting time (t). Using daily precipitation data for a period of 1960-2005 from 590 rain gauge stations in China, these two characteristics are analyzed, involving scaling and clustering of precipitation episodes. Our findings indicate that m and t follow similar probability distribution curves, implying that precipitation processes are controlled by similar underlying thermo-dynamics. Analysis of conditional probability distributions shows a significant dependence of m and t on their previous values of similar volumes, and the dependence tends to be stronger when m is larger or t is longer. It indicates that a higher probability can be expected when high-intensity precipitation is followed by precipitation episodes with similar precipitation intensity and longer waiting time between WPs is followed by the waiting time of similar duration. This result indicates the clustering of extreme precipitation episodes and severe droughts or floods are apt to occur in groups.

  14. Effect of humic substances on the precipitation of calcium phosphate

    Institute of Scientific and Technical Information of China (English)

    SONG Yong-hui; Hermann H. HAHN; Erhard HOFFMANN; Peter G. WEIDLER

    2006-01-01

    For phosphorus (P) recovery from wastewater, the effect of humic substances (HS) on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with synthetic water that contained 20 mg/L phosphate (as P) and 20 mg/L HS (as dissolved organic carbon, DOC) at a constant pH value in the range of 8.0-10.0. The concentration variations of phosphate, calcium (Ca) and HS were measured in the precipitation process; the crystalline state and compositions of the precipitates were analysed by powder X-ray diffraction (XRD) and chemical methods, respectively. It showed that at solution pH 8.0, the precipitation rate and removal efficiency of phosphate were greatly reduced by HS, but at solution pH ≥9.0,the effect of HS was very small. The Ca consumption for the precipitation of phosphate increased when HS was added; HS was also removed from solution with the precipitation of calcium phosphate. At solution pH 8.0 and HS concentrations ≤ 3.5 mg/L, and at pH ≥ 9.0 and HS concentrations ≤ 10 mg/L, the final precipitates were proved to be hydroxyapatite (HAP) by XRD. The increases of solution pH value and initial Ca/P ratio helped reduce the influence of HS on the precipitation of phosphate.

  15. Ostwald Ripening Process of Coherent β′ Precipitates during Aging in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 Alloys

    Directory of Open Access Journals (Sweden)

    N. Cayetano-Castro

    2015-01-01

    Full Text Available The Ostwald ripening process was studied in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 alloys after aging at 750, 850, and 950°C for different times. The microstructural evolution shows a rounded cube morphology (Fe, NiAl β′ precipitates aligned in the ferrite matrix, which changes to elongated plates after prolonged aging. The variation of the equivalent radii of precipitates with time follows the modified Lifshitz-Slyozov-Wagner theory for diffusion-controlled coarsening. Thermo-Calc analysis shows that the chromium content is richer in the matrix than in the precipitates which causes higher hardness and coarsening resistance in the aged Fe0.74Ni0.10Al0.15Cr0.01 alloy.

  16. Improving precipitation measurement

    Science.gov (United States)

    Strangeways, Ian

    2004-09-01

    Although rainfall has been measured for centuries scientifically and in isolated brief episodes over millennia for agriculture, it is still not measured adequately even today for climatology, water resources, and other precise applications. This paper outlines the history of raingauges, their errors, and describes the field testing over 3 years of a first guess design for an aerodynamic rain collector proposed by Folland in 1988. Although shown to have aerodynamic advantage over a standard 5 gauge, the new rain collector was found to suffer from outsplash in heavy rain. To study this problem, and to derive general basic design rules for aerodynamic gauges, its performance was investigated in turbulent, real-world conditions rather than in the controlled and simplified environment of a wind tunnel or mathematical model as in the past. To do this, video records were made using thread tracers to indicate the path of the wind, giving new insight into the complex flow of natural wind around and within raingauges. A new design resulted, and 2 years of field testing have shown that the new gauge has good aerodynamic and evaporative characteristics and minimal outsplash, offering the potential for improved precipitation measurement.

  17. Precipitation in the Solar System

    Science.gov (United States)

    McIntosh, Gordon

    2007-01-01

    As an astronomy instructor, I am always looking for commonly observed Earthly experiences to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote a short TPT article on frost. This paper is on the related phenomena of precipitation. Precipitation, so common on most of the Earth's…

  18. Kinetics of cadmium hydroxide precipitation

    International Nuclear Information System (INIS)

    Patterson, J.W.; Marani, D.; Luo, B.; Swenson, P.

    1987-01-01

    This paper presents some preliminary results on the kinetics of Cd(OH)/sub 2/ precipitation, both in the absence and the presence of citric acid as an inhibiting agent. Batch and continuous stirred tank reactor (CSTR) precipitation studies are performed by mixing equal volumes of NaOH and Cd(NO/sub 3/)/sub 2/ solutions, in order to avoid localized supersaturation conditions. The rate of metal removal from the soluble phase is calculated from the mass balance for the CSTR precipitation tests. In addition, precipitation kinetics are studied in terms of nucleation and crystal growth rates, by means of a particle counter that allows a population balance analysis for the precipitation reactor at steady state conditions

  19. [Stochastic characteristics of daily precipitation and its spatiotemporal difference over China based on information entropy].

    Science.gov (United States)

    Li, Xin Xin; Sang, Yan Fang; Xie, Ping; Liu, Chang Ming

    2018-04-01

    Daily precipitation process in China showed obvious randomness and spatiotemporal variation. It is important to accurately understand the influence of precipitation changes on control of flood and waterlogging disaster. Using the daily precipitation data measured at 520 stations in China during 1961-2013, we quantified the stochastic characteristics of daily precipitation over China based on the index of information entropy. Results showed that the randomness of daily precipitation in the southeast region were larger than that in the northwest region. Moreover, the spatial distribution of stochastic characteristics of precipitation was different at various grades. Stochastic characteri-stics of P 0 (precipitation at 0.1-10 mm) was large, but the spatial variation was not obvious. The stochastic characteristics of P 10 (precipitation at 10-25 mm) and P 25 (precipitation at 25-50 mm) were the largest and their spatial difference was obvious. P 50 (precipitation ≥50 mm) had the smallest stochastic characteristics and the most obviously spatial difference. Generally, the entropy values of precipitation obviously increased over the last five decades, indicating more significantly stochastic characteristics of precipitation (especially the obvious increase of heavy precipitation events) in most region over China under the scenarios of global climate change. Given that the spatial distribution and long-term trend of entropy values of daily precipitation could reflect thespatial distribution of stochastic characteristics of precipitation, our results could provide scientific basis for the control of flood and waterlogging disaster, the layout of agricultural planning, and the planning of ecological environment.

  20. Stress corrosion cracking evaluation of precipitation-hardening stainless steel

    Science.gov (United States)

    Humphries, T. S.; Nelson, E. E.

    1970-01-01

    Accelerated test program results show which precipitation hardening stainless steels are resistant to stress corrosion cracking. In certain cases stress corrosion susceptibility was found to be associated with the process procedure.

  1. Synthetic weather generator SYNTOR: Implementing improvements in precipitation generation

    Science.gov (United States)

    Infrequent high precipitation events produce a disproportionally large amount of the annual surface runoff, soil erosion, nutrient movement, and watershed sediment yield. Numerical simulation of these watershed processes often lack sufficiently long weather data records to adequately capture the sto...

  2. Model simulations with COSMO-SPECS: impact of heterogeneous freezing modes and ice nucleating particle types on ice formation and precipitation in a deep convective cloud

    Directory of Open Access Journals (Sweden)

    K. Diehl

    2018-03-01

    Full Text Available In deep convective clouds, heavy rain is often formed involving the ice phase. Simulations were performed using the 3-D cloud resolving model COSMO-SPECS with detailed spectral microphysics including parameterizations of homogeneous and three heterogeneous freezing modes. The initial conditions were selected to result in a deep convective cloud reaching 14 km of altitude with strong updrafts up to 40 m s−1. At such altitudes with corresponding temperatures below −40 °C the major fraction of liquid drops freezes homogeneously. The goal of the present model simulations was to investigate how additional heterogeneous freezing will affect ice formation and precipitation although its contribution to total ice formation may be rather low. In such a situation small perturbations that do not show significant effects at first sight may trigger cloud microphysical responses. Effects of the following small perturbations were studied: (1 additional ice formation via immersion, contact, and deposition modes in comparison to solely homogeneous freezing, (2 contact and deposition freezing in comparison to immersion freezing, and (3 small fractions of biological ice nucleating particles (INPs in comparison to higher fractions of mineral dust INP. The results indicate that the modification of precipitation proceeds via the formation of larger ice particles, which may be supported by direct freezing of larger drops, the growth of pristine ice particles by riming, and by nucleation of larger drops by collisions with pristine ice particles. In comparison to the reference case with homogeneous freezing only, such small perturbations due to additional heterogeneous freezing rather affect the total precipitation amount. It is more likely that the temporal development and the local distribution of precipitation are affected by such perturbations. This results in a gradual increase in precipitation at early cloud stages instead of a strong increase at

  3. Analyzing coastal precipitation using TRMM observations

    OpenAIRE

    R. H. Heiblum; I. Koren; O. Altaratz

    2011-01-01

    The interaction between breezes and synoptic gradient winds, and surface friction increase in transition from sea to land can create persistent convergence zones nearby coastlines. The low level convergence of moist air promotes the dynamical and microphysical processes responsible for the formation of clouds and precipitation.

    Our work focuses on the winter seasons of 1998–2011 in the Eastern Mediterranean. During the winter the Mediterranean sea is usually warmer than t...

  4. Characterization of Uranium Solids Precipitated with Aluminosilicates

    International Nuclear Information System (INIS)

    DUFF, MC

    2004-01-01

    At the Savannah River Site (SRS), the High-Level Waste (HLW) Tank Farms store and process high-level liquid radioactive wastes from the Canyons and recycle water from the Defense Waste Processing Facility. The waste is concentrated using evaporators to minimize the volume of space required for HLW storage. Recently, the 2H Evaporator was shutdown due to the crystallization of sodium aluminosilicate (NAS) solids (such as cancrinite and sodalite) that contained close to 10 weight percent of elementally-enriched uranium (U). Prior to extensive cleaning,the evaporator deposits resided on the evaporator walls and other exposed internal surfaces within the evaporator pot. Our goal is to support the basis for the continued safe operation of SRS evaporators and to gain more information that could be used to help mitigate U accumulation during evaporator operation. To learn more about the interaction between U(VI) and NAS in HLW salt solutions, we performed several fundamental studies to examine the mechanisms of U accumulation with NAS in highly caustic solutions. This larger group of studies focused on the following processes: co-precipitation/structural incorporation, sorption, and precipitation (with or without NAS), which will be reviewed in this presentation. We will present and discuss local atomic structural characterization data about U that has been co-precipitated with NAS solids (such as amorphous zeolite precursor material and sodalite) using X-ray absorption fine-structure (XAFS) spectroscopic techniques

  5. The Modification of Orographic Snow Growth Processes by Cloud Nucleating Aerosols

    Science.gov (United States)

    Cotton, W. R.; Saleeby, S.

    2011-12-01

    Cloud nucleating aerosols have been found to modify the amount and spatial distribution of snowfall in mountainous areas where riming growth of snow crystals is known to contribute substantially to the total snow water equivalent precipitation. In the Park Range of Colorado, a 2km deep supercooled liquid water orographic cloud frequently enshrouds the mountaintop during snowfall events. This leads to a seeder-feeder growth regime in which snow falls through the orographic cloud and collects cloud water prior to surface deposition. The addition of higher concentrations of cloud condensation nuclei (CCN) modifies the cloud droplet spectrum toward smaller size droplets and suppresses riming growth. Without rime growth, the density of snow crystals remains low and horizontal trajectories carry them further downwind due to slower vertical fall speeds. This leads to a downwind shift in snowfall accumulation at high CCN concentrations. Cloud resolving model simulations were performed (at 600m horizontal grid spacing) for six snowfall events over the Park Range. The chosen events were well simulated and occurred during intensive observations periods as part of two winter field campaigns in 2007 and 2010 based at Storm Peak Laboratory in Steamboat Springs, CO. For each event, sensitivity simulations were run with various initial CCN concentration vertical profiles that represent clean to polluted aerosol environments. Microphysical budget analyses were performed for these simulations in order to determine the relative importance of the various cloud properties and growth processes that contribute to precipitation production. Observations and modeling results indicate that initial vapor depositional growth of snow tends to be maximized within about 1km of mountaintop above the windward slope while the majority of riming growth occurs within 500m of mountaintop. This suggests that precipitation production is predominantly driven by locally enhanced orography. The large scale

  6. Precipitation of hydrides in high purity niobium after different treatments

    Energy Technology Data Exchange (ETDEWEB)

    Barkov, F.; Romanenko, A.; Trenikhina, Y.; Grassellino, A.

    2013-01-01

    Precipitation of lossy non-superconducting niobium hydrides represents a known problem for high purity niobium in superconducting applications. Using cryogenic optical and laser confocal scanning microscopy we have directly observed surface precipitation and evolution of niobium hydrides in samples after different treatments used for superconducting RF cavities for particle acceleration. Precipitation is shown to occur throughout the sample volume, and the growth of hydrides is well described by the fast diffusion-controlled process in which almost all hydrogen is precipitated at $T=140$~K within $\\sim30$~min. 120$^{\\circ}$C baking and mechanical deformation are found to affect hydride precipitation through their influence on the number of nucleation and trapping centers.

  7. Temporal variation of extreme precipitation events in Lithuania

    Directory of Open Access Journals (Sweden)

    Egidijus Rimkus

    2011-05-01

    Full Text Available Heavy precipitation events in Lithuania for the period 1961-2008 were analysed. The spatial distribution and dynamics of precipitation extremes were investigated. Positive tendencies and in some cases statistically significant trends were determined for the whole of Lithuania. Atmospheric circulation processes were derived using Hess & Brezowski's classification of macrocirculation forms. More than one third of heavy precipitation events (37% were observed when the atmospheric circulation was zonal. The location of the central part of a cyclone (WZ weather condition subtype over Lithuania is the most common synoptic situation (27% during heavy precipitation events. Climatic projections according to outputs of the CCLM model are also presented in this research. The analysis shows that the recurrence of heavy precipitation events in the 21st century will increase significantly (by up to 22% in Lithuania.

  8. Regime-dependent forecast uncertainty of convective precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Keil, Christian; Craig, George C. [Muenchen Univ. (Germany). Meteorologisches Inst.

    2011-04-15

    Forecast uncertainty of convective precipitation is influenced by all scales, but in different ways in different meteorological situations. Forecasts of the high resolution ensemble prediction system COSMO-DE-EPS of Deutscher Wetterdienst (DWD) are used to examine the dominant sources of uncertainty of convective precipitation. A validation with radar data using traditional as well as spatial verification measures highlights differences in precipitation forecast performance in differing weather regimes. When the forecast uncertainty can primarily be associated with local, small-scale processes individual members run with the same variation of the physical parameterisation driven by different global models outperform all other ensemble members. In contrast when the precipitation is governed by the large-scale flow all ensemble members perform similarly. Application of the convective adjustment time scale confirms this separation and shows a regime-dependent forecast uncertainty of convective precipitation. (orig.)

  9. On the Precipitation and Precipitation Change in Alaska

    Directory of Open Access Journals (Sweden)

    Gerd Wendler

    2017-12-01

    Full Text Available Alaska observes very large differences in precipitation throughout the state; southeast Alaska experiences consistently wet conditions, while northern Arctic Alaska observes very dry conditions. The maximum mean annual precipitation of 5727 mm is observed in the southeastern panhandle at Little Port Arthur, while the minimum of 92 mm occurs on the North Slope at Kuparuk. Besides explaining these large differences due to geographic and orographic location, we discuss the changes in precipitation with time. Analyzing the 18 first-order National Weather Service stations, we found that the total average precipitation in the state increased by 17% over the last 67 years. The observed changes in precipitation are furthermore discussed as a function of the observed temperature increase of 2.1 °C, the mean temperature change of the 18 stations over the same period. This observed warming of Alaska is about three times the magnitude of the mean global warming and allows the air to hold more water vapor. Furthermore, we discuss the effect of the Pacific Decadal Oscillation (PDO, which has a strong influence on both the temperature and precipitation in Alaska.

  10. Investigation of Neptunium Precipitator Cleanout Options

    International Nuclear Information System (INIS)

    Hill, B.C.

    2003-01-01

    Oxalate precipitation followed by filtration is used to prepare plutonium oxalate. Historically, plutonium oxalate has tended to accumulate in the precipitation tanks. These solids are periodically removed by flushing with concentrated (64 percent) nitric acid. The same precipitation tanks will now be used in the processing of neptunium. Literature values indicate that neptunium oxalate may not be as soluble as plutonium oxalate in nitric acid. Although a wide variety of options is available to improve neptunium oxalate solubility for precipitator flushing, most of these options are not practical for use. Many of these options require the use of incompatible or difficult to handle chemicals. Other options would require expensive equipment modifications or are likely to lead to product contamination. Based on review of literature and experimental results, the two best options for flushing the precipitator are (1) 64 percent nitric acid and (2) addition of sodium permanganate follow ed by sodium nitrite. Nitric acid is the easiest option to implement. It is already used in the facility and will not lead to product contamination. Experimental results indicate that neptunium oxalate can be dissolved in concentrated nitric acid (64 percent) at 60 degree C to a concentration of 2.6 to 5.6 grams of Np/liter after at least three hours of heating. A lower concentration (1.1 grams of Np/liter) was measured at 60 degree C after less than two hours of heating. These concentrations are acceptable for flushing if precipitator holdup is low (approximately 100-250 grams), but a second method is required for effective flushing if precipitator holdup is high (approximately 2 kilograms). The most effective method for obtaining higher neptunium concentrations is the use of sodium permanganate followed by the addition of sodium nitrite. There is concern that residual manganese from these flushes could impact product purity. Gas generation during permanganate addition is also a concern

  11. Effect of austenite deformation temperature on Nb clustering and precipitation in microalloyed steel

    International Nuclear Information System (INIS)

    Pereloma, E.V.; Kostryzhev, A.G.; AlShahrani, A.; Zhu, C.; Cairney, J.M.; Killmore, C.R.; Ringer, S.P.

    2014-01-01

    The effect of thermomechanical processing conditions on Nb clustering and precipitation in both austenite and ferrite in a Nb–Ti microalloyed steel was studied using electron microscopy and atom probe tomography. A decrease in the deformation temperature increased the Nb-rich precipitation in austenite and decreased the extent of precipitation in ferrite. Microstructural mechanisms that explain this variation are discussed

  12. Modeling of Precipitation Sequence and Ageing Kinetics in Al-Mg-Si Alloys

    NARCIS (Netherlands)

    Bahrami, A.

    2010-01-01

    Al-Mg-Si alloys are heat treatable alloys in which strength is obtained by precipitation hardening. Precipitates, formed from a supersaturated solid solution during ageing heat treatment, are GP-zones, B", B´ and B-Mg2Si. Precipitation kinetics and strength vary with alloy composition and process

  13. Factors controlling stable isotope composition of European precipitation

    International Nuclear Information System (INIS)

    Rozanski, K.; Sonntag, C.; Muennich, K.O.

    1982-01-01

    The seasonal and spatial variations of stable isotope ratios in present day European precipitation are simulated with a simple multibox model of the mean west-east horizontal transport of the atmospheric water vapour across the European continent. Isotope fractionation during the formation of precipitation leads to an increasing depletion of heavy isotopes in the residual air moisture as it moves towards the centre of the continent. This isotopic depletion is partly compensated, particularly in summer, by evapotranspiration, which is assumed to transfer soil water into the atmosphere without isotope fractionation. The model estimates are based on horizontal water vapour flux data, varying seasonally between 88 and 130 kg m -1 s -1 for the Atlantic coast region, and on the monthly precipitation, evapotranspiration and surface air temperature data available for various locations in Europe. Both continental and seasonal temperature effects observed in the stable isotope composition of European precipitation are fairly well reproduced by the model. The calculations show that the isotopic composition of local precipitation is primarily controlled by regional scale processes, i.e. by the water vapour transport patterns into the continent, and by the average precipitation-evapotranspiration history of the air masses precipitating at a given place. Local parameters such as the surface and/or cloud base temperature or the amount of precipitation modify the isotope ratios only slightly. Implications of the model predictions for the interpretation of stable isotope ratios in earlier periods as they are preserved in ice cores and in groundwater are also discussed. (Auth.)

  14. Analysis of precipitation teleconnections in CMIP models as a measure of model fidelity in simulating precipitation

    Science.gov (United States)

    Langenbrunner, B.; Neelin, J.; Meyerson, J.

    2011-12-01

    The accurate representation of precipitation is a recurring issue in global climate models, especially in the tropics. Poor skill in modeling the variability and climate teleconnections associated with El Niño/Southern Oscillation (ENSO) also persisted in the latest Climate Model Intercomparison Project (CMIP) campaigns. Observed ENSO precipitation teleconnections provide a standard by which we can judge a given model's ability to reproduce precipitation and dynamic feedback processes originating in the tropical Pacific. Using CMIP3 Atmospheric Model Intercomparison Project (AMIP) runs as a baseline, we compare precipitation teleconnections between models and observations, and we evaluate these results against available CMIP5 historical and AMIP runs. Using AMIP simulations restricts evaluation to the atmospheric response, as sea surface temperatures (SSTs) in AMIP are prescribed by observations. We use a rank correlation between ENSO SST indices and precipitation to define teleconnections, since this method is robust to outliers and appropriate for non-Gaussian data. Spatial correlations of the modeled and observed teleconnections are then evaluated. We look at these correlations in regions of strong precipitation teleconnections, including equatorial S. America, the "horseshoe" region in the western tropical Pacific, and southern N. America. For each region and season, we create a "normalized projection" of a given model's teleconnection pattern onto that of the observations, a metric that assesses the quality of regional pattern simulations while rewarding signals of correct sign over the region. Comparing this to an area-averaged (i.e., more generous) metric suggests models do better when restrictions on exact spatial dependence are loosened and conservation constraints apply. Model fidelity in regional measures remains far from perfect, suggesting intrinsic issues with the models' regional sensitivities in moist processes.

  15. Precipitation of lithium in germanium

    International Nuclear Information System (INIS)

    Masaik, M.; Furgolle, B.

    1969-01-01

    The precipitation of Lithium in Germanium was studied. Taking account of the interactions Ga LI, LiO, we calculated the oxygen content in germanium samples from the resistivity measurements. (authors)

  16. Environmental Radioactivity, Temperature, and Precipitation.

    Science.gov (United States)

    Riland, Carson A.

    1996-01-01

    Reports that environmental radioactivity levels vary with temperature and precipitation and these effects are due to radon. Discusses the measurement of this environmental radioactivity and the theory behind it. (JRH)

  17. Hourly and Daily Precipitation Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Precipitation reports submitted on many form types, including tabular and autographic charts. Reports are almost exclusively from the US Cooperative Observer Network.

  18. Evaluation of Coupled Precipitator Two

    International Nuclear Information System (INIS)

    Stone, M.E.

    1999-01-01

    The offline testing of the Coupled Precipitator Two (CP-2) has been completed. The tests were conducted and are documented. The tests were conducted at an offline test rack near the Drain Tube Test Stand facility in 672-T

  19. Developing precipitation hardenable high entropy alloys

    Science.gov (United States)

    Gwalani, Bharat

    High entropy alloys (HEAs) is a concept wherein alloys are constructed with five or more elements mixed in equal proportions; these are also known as multi-principle elements (MPEs) or complex concentrated alloys (CCAs). This PhD thesis dissertation presents research conducted to develop precipitation-hardenable high entropy alloys using a much-studied fcc-based equi-atomic quaternary alloy (CoCrFeNi). Minor additions of aluminium make the alloy amenable for precipitating ordered intermetallic phases in an fcc matrix. Aluminum also affects grain growth kinetics and Hall-Petch hardenability. The use of a combinatorial approach for assessing composition-microstructure-property relationships in high entropy alloys, or more broadly in complex concentrated alloys; using laser deposited compositionally graded AlxCrCuFeNi 2 (0 mechanically processed via conventional techniques. The phase stability and mechanical properties of these alloys have been investigated and will be presented. Additionally, the activation energy for grain growth as a function of Al content in these complex alloys has also been investigated. Change in fcc grain growth kinetic was studied as a function of aluminum; the apparent activation energy for grain growth increases by about three times going from Al0.1CoCrFeNi (3% Al (at%)) to Al0.3CoCrFeNi. (7% Al (at%)). Furthermore, Al addition leads to the precipitation of highly refined ordered L12 (gamma') and B2 precipitates in Al0.3CoCrFeNi. A detailed investigation of precipitation of the ordered phases in Al0.3CoCrFeNi and their thermal stability is done using atom probe tomography (APT), transmission electron microscopy (TEM) and Synchrotron X-ray in situ and ex situ analyses. The alloy strengthened via grain boundary strengthening following the Hall-Petch relationship offers a large increment of strength with small variation in grain size. Tensile strength of the Al0.3CoFeNi is increased by 50% on precipitation fine-scale gamma' precipitates

  20. MODELING OF ISOTHERMAL PRECIPITATION KINETICS IN HSLA STEELS AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    X.M. Zhao; D. Wu; L.Z. Zhang; Z.Y. Liu

    2004-01-01

    Microalloying elements in high-strength low-alloy steels, such as Nb, Ti and V, precipitate during hot-rolling processes. On the basis of classical theory of nucleation and growth, quantitative modeling of isothermal precipitation was developed, which was tested by the stress relaxation method, the calculated precipitation-time-temperature curve is in good agreements with the measured results, then the model was applied to predict the precipitation behavior during continuous cooling.

  1. Discontinuous precipitation in cobalt-tungsten alloys

    International Nuclear Information System (INIS)

    Zieba, P.; Cliff, G.; Lorimer, G.W.

    1997-01-01

    Discontinuous precipitation in a Co32 wt% W alloy aged in the temperature range from 875 K to 1025 K has been investigated. Philips EM 430 STEM has been used to characterize the microstructure and to measure the composition profiles across individual lamellae of ε Co and Co 3 W phases in partially transformed specimens. Two kinds of cellular precipitates have been found in the alloy. The initial transformation product, identified as primary lamellae with spacing of a few nanometers is replaced during prolonged ageing by secondary lamellae with a much larger interlamellar spacing, typically a few tens of nm. Line scans across cell boundaries of the primary lamellae revealed that, just behind the advancing cell boundary, the solute content is far from the equilibrium state. This solute excess within the cells is quickly removed at the ageing temperature. Calculations show that the diffusion process was too rapid to be identified as ordinary volume diffusion. Investigation of the kinetics showed that discontinuous precipitation is controlled by diffusion processes at the advancing cell boundary. This proposal has been confirmed by STEM analysis of tungsten profiles in the depleted ε Co lamellae

  2. Forecasting Monsoon Precipitation Using Artificial Neural Networks

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper explores the application of Artificial Intelligent (AI) techniques for climate forecast. It pres ents a study on modelling the monsoon precipitation forecast by means of Artificial Neural Networks (ANNs). Using the historical data of the total amount of summer rainfall over the Delta Area of Yangtze River in China, three ANNs models have been developed to forecast the monsoon precipitation in the corre sponding area one year, five-year, and ten-year forward respectively. Performances of the models have been validated using a 'new' data set that has not been exposed to the models during the processes of model development and test. The experiment results are promising, indicating that the proposed ANNs models have good quality in terms of the accuracy, stability and generalisation ability.

  3. ARM Cloud Aerosol Precipitation Experiment (ACAPEX) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Leung, L. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Prather, K. [Scripps Institution of Oceanography, La Jolla, CA (United States); Ralph, R. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Rosenfeld, D. [The Hebrew University of Jerusalem (Israel); Spackman, R. [Science and Technology Corporation (STC), Hampton, VA (United States); DeMott, P. [Colorado State Univ., Fort Collins, CO (United States); Fairall, C. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Fan, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hagos, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hughes, M. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Long, C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rutledge, S. [Colorado State Univ., Fort Collins, CO (United States); Waliser, D. [National Aeronautics and Space Administration (NASA), Washington, DC (United States); Wang, H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-09-01

    The western U.S. receives precipitation predominantly during the cold season when storms approach from the Pacific Ocean. The snowpack that accumulates during winter storms provides about 70-90% of water supply for the region. Understanding and modeling the fundamental processes that govern the large precipitation variability and extremes in the western U.S. is a critical test for the ability of climate models to predict the regional water cycle, including floods and droughts. Two elements of significant importance in predicting precipitation variability in the western U.S. are atmospheric rivers and aerosols. Atmospheric rivers (ARs) are narrow bands of enhanced water vapor associated with the warm sector of extratropical cyclones over the Pacific and Atlantic oceans. Because of the large lower-tropospheric water vapor content, strong atmospheric winds and neutral moist static stability, some ARs can produce heavy precipitation by orographic enhancement during landfall on the U.S. West Coast. While ARs are responsible for a large fraction of heavy precipitation in that region during winter, much of the rest of the orographic precipitation occurs in post-frontal clouds, which are typically quite shallow, with tops just high enough to pass the mountain barrier. Such clouds are inherently quite susceptible to aerosol effects on both warm rain and ice precipitation-forming processes.

  4. Uranium (III) precipitation in molten chloride by wet argon sparging

    Energy Technology Data Exchange (ETDEWEB)

    Vigier, Jean-François, E-mail: jean-francois.vigier@ec.europa.eu [CEA, Nuclear Energy Division, Radiochemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Laplace, Annabelle [CEA, Nuclear Energy Division, Radiochemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Renard, Catherine [Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Miguirditchian, Manuel [CEA, Nuclear Energy Division, Radiochemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Abraham, Francis [Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France)

    2016-06-15

    In the context of pyrochemical processes for nuclear fuel treatment, the precipitation of uranium (III) in molten salt LiCl-CaCl{sub 2} (30–70 mol%) at 705 °C is studied. First, this molten chloride is characterized with the determination of the water dissociation constant. With a value of 10{sup −4.0}, the salt has oxoacid properties. Then, the uranium (III) precipitation using wet argon sparging is studied. The salt is prepared using UCl{sub 3} precursor. At the end of the precipitation, the salt is totally free of solubilized uranium. The main part is converted into UO{sub 2} powder but some uranium is lost during the process due to the volatility of uranium chloride. The main impurity of the resulting powder is calcium. The consequences of oxidative and reductive conditions on precipitation are studied. Finally, coprecipitation of uranium (III) and neodymium (III) is studied, showing a higher sensitivity of uranium (III) than neodymium (III) to precipitation. - Highlights: • Precipitation of Uranium (III) is quantitative in molten salt LiCl-CaCl{sub 2} (30–70 mol%). • The salt is oxoacid with a water dissociation constant of 10{sup −4.0} at 705 °C. • Volatility of uranium chloride is strongly reduced in reductive conditions. • Coprecipitation of U(III) and Nd(III) leads to a consecutive precipitation of the two elements.

  5. Development of precipitator of fluid film type

    International Nuclear Information System (INIS)

    Liu Yupu

    1987-01-01

    The precipitator of fluid film type is developed for the determination of fuel element cladding failure of water-cooled reactor. It integrates the scrubber, precipitator and detector. The jet of element cooling water automatically circulates carrier gas and the flow water film transfers precipitates onto the surface of centre electrode. Three different types are designed. On the special test loop, the uranium sample pellets of simulating cladding failure is measured. The sensitivity of precipitators, saturated precipitation voltage, incremental speed of signal, speed of driving out precipitates and the contents of the precipitates are determined. The test shows that the precipitators are highly sensitive, reliable, cheap and easy to operate

  6. Radionuclide co-precipitation

    International Nuclear Information System (INIS)

    Bruno, J.; Sandino, A.

    1987-12-01

    The thermodynamic and kinetic behaviour of the minor components of the spent fuel matrix has been theoretically and experimentally investigated. Two different situations have been studied: Part I, the near field scenario, where the release and migration of the minor components is dependent on the solubility behaviour of UO 2 (s); Part II, the far field, where the solubility and transport of the radionuclides is related to the major geochemical processes occurring. (orig.)

  7. Grain boundary precipitation in an austenitic stainless steel

    International Nuclear Information System (INIS)

    Jones, A.R.; Howell, P.R.; Ralph, B.

    The precipitation of second phase particles of niobium carbide in an austenitic stainless steel is shown to be considerably influenced by the degree of deformation introduced prior to the ageing treatment. Sites for the nucleation of second phase particles are identified and the importance of one type of nucleation site, extrinsic dislocations, to the evolution of the final boundary precipitate distributions is emphasized. Further, it is shown that the presence of a grain boundary can effect precipitation processes for some considerable distance into the matrix on either side of the boundary. (author)

  8. An Innovative Metric to Evaluate Satellite Precipitation's Spatial Distribution

    Science.gov (United States)

    Liu, H.; Chu, W.; Gao, X.; Sorooshian, S.

    2011-12-01

    Thanks to its capability to cover the mountains, where ground measurement instruments cannot reach, satellites provide a good means of estimating precipitation over mountainous regions. In regions with complex terrains, accurate information on high-resolution spatial distribution of precipitation is critical for many important issues, such as flood/landslide warning, reservoir operation, water system planning, etc. Therefore, in order to be useful in many practical applications, satellite precipitation products should possess high quality in characterizing spatial distribution. However, most existing validation metrics, which are based on point/grid comparison using simple statistics, cannot effectively measure satellite's skill of capturing the spatial patterns of precipitation fields. This deficiency results from the fact that point/grid-wised comparison does not take into account of the spatial coherence of precipitation fields. Furth more, another weakness of many metrics is that they can barely provide information on why satellite products perform well or poor. Motivated by our recent findings of the consistent spatial patterns of the precipitation field over the western U.S., we developed a new metric utilizing EOF analysis and Shannon entropy. The metric can be derived through two steps: 1) capture the dominant spatial patterns of precipitation fields from both satellite products and reference data through EOF analysis, and 2) compute the similarities between the corresponding dominant patterns using mutual information measurement defined with Shannon entropy. Instead of individual point/grid, the new metric treat the entire precipitation field simultaneously, naturally taking advantage of spatial dependence. Since the dominant spatial patterns are shaped by physical processes, the new metric can shed light on why satellite product can or cannot capture the spatial patterns. For demonstration, a experiment was carried out to evaluate a satellite

  9. Acceleration and Precipitation of Electrons during Substorm Dipolarization Events

    Science.gov (United States)

    Ashour-Abdalla, Maha; Richard, Robert; Donovan, Eric; Zhou, Meng; Goldstein, Mevlyn; El-Alaoui, Mostafa; Schriver, David; Walker, Raymond

    Observations and modeling have established that during geomagnetically disturbed times the Earth’s magnetotail goes through large scale changes that result in enhanced electron precipitation into the ionosphere and earthward propagating dipolarization fronts that contain highly energized plasma. Such events originate near reconnection regions in the magnetotail at about 20-30 R_E down tail. As the dipolarization fronts propagate earthward, strong acceleration of both ions and electrons occurs due to a combination of non-adiabatic and adiabatic (betatron and Fermi) acceleration, with particle energies reaching up to 100 keV within the dipolarization front. One consequence of the plasma transport that occurs during these events is direct electron precipitation into the ionosphere, which form auroral precipitation. Using global kinetic simulations along with spacecraft and ground-based data, causes of electron precipitation are determined during well-documented, disturbed events. It is found that precipitation of keV electrons in the pre-midnight sector at latitudes around 70(°) occur due to two distinct physical processes: (1) higher latitude (≥72(°) ) precipitation due to electrons that undergo relatively rapid non-adiabatic pitch angle scattering into the loss cone just earthward of the reconnection region at around 20 R_E downtail, and (2) lower latitude (≤72(°) ) precipitation due to electrons that are more gradually accelerated primarily parallel to the geomagnetic field during its bounce motion by Fermi acceleration and enter the loss cone much closer to the Earth at 10-15 R_E, somewhat tailward of the dipolarization front. As the dipolarization fronts propagate earthward, the electron precipitation shifts to lower latitudes and occurs over a wider region in the auroral ionosphere. Our results show a direct connection between electron acceleration in the magnetotail and electron precipitation in the ionosphere during disturbed times. The electron

  10. Influence of equal-channel angular pressing on precipitation in an Al-Zn-Mg-Cu alloy

    International Nuclear Information System (INIS)

    Sha, G.; Wang, Y.B.; Liao, X.Z.; Duan, Z.C.; Ringer, S.P.; Langdon, T.G.

    2009-01-01

    Processing by equal-channel angular pressing (ECAP) affects the morphology of η precipitates in an Al-Zn-Mg-Cu (Al-7136) alloy. It is shown by transmission electron microscopy that ECAP changes the orientation of precipitates and this influences the atomic configuration and the interfacial energy at the η/α-Al interfaces. Consequently, η precipitates adopt an isotropic growth mode and evolve into equiaxed particles. A three-dimensional atom probe analysis demonstrates that large η precipitates formed in different numbers of ECAP passes are of similar composition. The coalescence of smaller precipitates, rather than the fragmentation of larger precipitates, dominates the precipitate evolution.

  11. Satellite-Based Precipitation Datasets

    Science.gov (United States)

    Munchak, S. J.; Huffman, G. J.

    2017-12-01

    Of the possible sources of precipitation data, those based on satellites provide the greatest spatial coverage. There is a wide selection of datasets, algorithms, and versions from which to choose, which can be confusing to non-specialists wishing to use the data. The International Precipitation Working Group (IPWG) maintains tables of the major publicly available, long-term, quasi-global precipitation data sets (http://www.isac.cnr.it/ ipwg/data/datasets.html), and this talk briefly reviews the various categories. As examples, NASA provides two sets of quasi-global precipitation data sets: the older Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and current Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) mission (IMERG). Both provide near-real-time and post-real-time products that are uniformly gridded in space and time. The TMPA products are 3-hourly 0.25°x0.25° on the latitude band 50°N-S for about 16 years, while the IMERG products are half-hourly 0.1°x0.1° on 60°N-S for over 3 years (with plans to go to 16+ years in Spring 2018). In addition to the precipitation estimates, each data set provides fields of other variables, such as the satellite sensor providing estimates and estimated random error. The discussion concludes with advice about determining suitability for use, the necessity of being clear about product names and versions, and the need for continued support for satellite- and surface-based observation.

  12. The Fractionation and Enrichment of La Content by Precipitation

    International Nuclear Information System (INIS)

    Suyanti; Purwani, MV

    2007-01-01

    The fractionation and enrichment of La content by precipitation have been done. The feed was La hydroxide by product of monazite sand. La hydroxide was diluted in HNO 3 and was precipitated with ammonia. For to obtain La, diluent was precipitated at pH 8 and the filtrate was precipitated with oxalic acid. The precipitant of La concentrated was more rich than the feed. This process was done continue and fractionally. The best yield of enrichment of La was obtained at dilution of 25 gram La Hydroxide in 20 ml HNO 3 . The efficient degree of fractionation was XV. The average weight of La concentrate was obtained at every fraction was 1 gram. The total sum weight from fraction I until fraction XV 13.5 grams. The average of La content was 48%, average fractionation efficiency of La for every step of fractionation was 48 %. Total efficiency all process was 100%. The average ratio of La/Nd was 2 and the ratio of La/Ce almost infinite. Before processed La/Ce was 7.86, and after process increase to 26.92 - to approach ∞. Before processed ratio of La/Nd was 2.79, after processed increased to 4.4 - to approach ∞. (author)

  13. A subgrid parameterization scheme for precipitation

    Directory of Open Access Journals (Sweden)

    S. Turner

    2012-04-01

    Full Text Available With increasing computing power, the horizontal resolution of numerical weather prediction (NWP models is improving and today reaches 1 to 5 km. Nevertheless, clouds and precipitation formation are still subgrid scale processes for most cloud types, such as cumulus and stratocumulus. Subgrid scale parameterizations for water vapor condensation have been in use for many years and are based on a prescribed probability density function (PDF of relative humidity spatial variability within the model grid box, thus providing a diagnosis of the cloud fraction. A similar scheme is developed and tested here. It is based on a prescribed PDF of cloud water variability and a threshold value of liquid water content for droplet collection to derive a rain fraction within the model grid. Precipitation of rainwater raises additional concerns relative to the overlap of cloud and rain fractions, however. The scheme is developed following an analysis of data collected during field campaigns in stratocumulus (DYCOMS-II and fair weather cumulus (RICO and tested in a 1-D framework against large eddy simulations of these observed cases. The new parameterization is then implemented in a 3-D NWP model with a horizontal resolution of 2.5 km to simulate real cases of precipitating cloud systems over France.

  14. Measurement of precipitation using lysimeters

    Science.gov (United States)

    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

  15. Arsenic precipitation from metallurgical effluents

    International Nuclear Information System (INIS)

    Navarro, P.; Vargas, C.; Araya, E.; Martin, I.; Alguacil, F. J.

    2004-01-01

    In the mining-metallurgical companies different liquid effluents are produced, which can contain a series of dissolved elements that are considered dangerous from an environmental point of view. One of these elements is the arsenic, especially in the state of oxidation +5 that can be precipitated as calcium or iron arsenate. To fulfil the environmental requests it should have in solution a content of arsenic lower than 0,5 mg/l and the obtained solid product should be very stable under the condition in which it will be stored. this work looks for the best conditions of arsenic precipitation, until achieving contents in solution lower than such mentioned concentration. Also, the stability of the precipitates was studied. (Author) 7 refs

  16. Transient bedrock channel evolution across a precipitation gradient: A case study from Kohala, Hawaii.

    Science.gov (United States)

    Gasparini, N. M.; Han, J.; Johnson, J. P.; Menking, J. A.

    2011-12-01

    This study uses observations from the Kohala Peninsula, on the Big Island of Hawaii, and numerical modeling, to explore how precipitation gradients may affect fluvial bedrock incision and channel morphology. Orographic precipitation patterns result in over 4 m/yr of rainfall on the wet side of the peninsula and less than 0.5 m/yr on the dry side. These precipitation patterns likely strongly contribute to the observed channel morphology. Further, the region is subsiding, leading to prolonged transient channel evolution. We explore changes in a number of channel morphologic parameters with watershed averaged precipitation rate. We use PRISM precipitation data and data from isohyets developed from historic rain gauge data. Not surprisingly, valley depth, measured from a 10 meter DEM, increases with spatially averaged precipitation rate. We also find that channel profile form varies with precipitation rate, with drier channels exhibiting a straight to slightly concave channel form and wetter channels exhibiting a convex to concave channel form. The precipitation value at which this transition in channel profile form occurs depends on the precipitation data-set used, highlighting the need for more accurate measurements of precipitation in settings with extreme precipitation patterns similar to our study area. The downstream pattern in precipitation is likely significant in the development of the convex-concave profile form. Numerical modeling results support that precipitation patterns such as those observed on the wet-side of the Kohala Peninsula may contribute to the convex-concave profile form. However, we emphasize that while precipitation patterns may contribute to the channel form, these channel features are transient and not expected to be sustained in steady-state landscapes. We also emphasize that it is fluvial discharge, as driven by precipitation, rather than precipitation alone, that drives the processes shaping the channel form. Because fluvial discharge is

  17. Radar-Derived Quantitative Precipitation Estimation Based on Precipitation Classification

    Directory of Open Access Journals (Sweden)

    Lili Yang

    2016-01-01

    Full Text Available A method for improving radar-derived quantitative precipitation estimation is proposed. Tropical vertical profiles of reflectivity (VPRs are first determined from multiple VPRs. Upon identifying a tropical VPR, the event can be further classified as either tropical-stratiform or tropical-convective rainfall by a fuzzy logic (FL algorithm. Based on the precipitation-type fields, the reflectivity values are converted into rainfall rate using a Z-R relationship. In order to evaluate the performance of this rainfall classification scheme, three experiments were conducted using three months of data and two study cases. In Experiment I, the Weather Surveillance Radar-1988 Doppler (WSR-88D default Z-R relationship was applied. In Experiment II, the precipitation regime was separated into convective and stratiform rainfall using the FL algorithm, and corresponding Z-R relationships were used. In Experiment III, the precipitation regime was separated into convective, stratiform, and tropical rainfall, and the corresponding Z-R relationships were applied. The results show that the rainfall rates obtained from all three experiments match closely with the gauge observations, although Experiment II could solve the underestimation, when compared to Experiment I. Experiment III significantly reduced this underestimation and generated the most accurate radar estimates of rain rate among the three experiments.

  18. Method of removing clogging materials due to ruthenium precipitates and sealing them in device

    International Nuclear Information System (INIS)

    Hoshikawa, Tadahiro; Sasahira, Akira.

    1994-01-01

    In a facility, such as a reprocessing facility, for processing a solution containing a great amount of ruthenium, precipitates due to evaporated ruthenium and cooled NO x are brought into contact with each other to decompose the precipitates due to the evaporated ruthenium. Precipitates due to ruthenium evaporated from the solution are reacted with cooled NO x , and the precipitates of ruthenium are decomposed and returned to the solution in the form of extremely fine particles together with recycling flow from the inner wall of the device. Since the precipitates of ruthenium returned to the solution are stable, they are no more evaporated and precipitated on the inner wall of the device. In the solution processing device having a possibility of clogging, clogging can be prevented and the precipitates of ruthenium can be sealed by decomposing them. (T.M.)

  19. Patterning of alloy precipitation through external pressure

    Science.gov (United States)

    Franklin, Jack A.

    Due to the nature of their microstructure, alloyed components have the benefit of meeting specific design goals across a wide range of electrical, thermal, and mechanical properties. In general by selecting the correct alloy system and applying a proper heat treatment it is possible to create a metallic sample whose properties achieve a unique set of design requirements. This dissertation presents an innovative processing technique intended to control both the location of formation and the growth rates of precipitates within metallic alloys in order to create multiple patterned areas of unique microstructure within a single sample. Specific experimental results for the Al-Cu alloy system will be shown. The control over precipitation is achieved by altering the conventional heat treatment process with an external surface load applied to selected locations during the quench and anneal. It is shown that the applied pressures affect both the rate and directionality of the atomic diffusion in regions close to the loaded surfaces. The control over growth rates is achieved by altering the enthalpic energy required for successful diffusion between lattice sites. Changes in the local chemical free energy required to direct the diffusion of atoms are established by introducing a non-uniform elastic strain energy field within the samples created by the patterned surface pressures. Either diffusion rates or atomic mobility can be selected as the dominating control process by varying the quench rate; with slower quenches having greater control over the mobility of the alloying elements. Results have shown control of Al2Cu precipitation over 100 microns on mechanically polished surfaces. Further experimental considerations presented will address consistency across sample ensembles. This includes repeatable pressure loading conditions and the chemical interaction between any furnace environments and both the alloy sample and metallic pressure loading devices.

  20. Dynamical response of Mediterranean precipitation to greenhouse gases and aerosols

    Directory of Open Access Journals (Sweden)

    T. Tang

    2018-06-01

    Full Text Available Atmospheric aerosols and greenhouse gases affect cloud properties, radiative balance and, thus, the hydrological cycle. Observations show that precipitation has decreased in the Mediterranean since the beginning of the 20th century, and many studies have investigated possible mechanisms. So far, however, the effects of aerosol forcing on Mediterranean precipitation remain largely unknown. Here we compare the modeled dynamical response of Mediterranean precipitation to individual forcing agents in a set of global climate models (GCMs. Our analyses show that both greenhouse gases and aerosols can cause drying in the Mediterranean and that precipitation is more sensitive to black carbon (BC forcing than to well-mixed greenhouse gases (WMGHGs or sulfate aerosol. In addition to local heating, BC appears to reduce precipitation by causing an enhanced positive sea level pressure (SLP pattern similar to the North Atlantic Oscillation–Arctic Oscillation, characterized by higher SLP at midlatitudes and lower SLP at high latitudes. WMGHGs cause a similar SLP change, and both are associated with a northward diversion of the jet stream and storm tracks, reducing precipitation in the Mediterranean while increasing precipitation in northern Europe. Though the applied forcings were much larger, if forcings are scaled to those of the historical period of 1901–2010, roughly one-third (31±17 % of the precipitation decrease would be attributable to global BC forcing with the remainder largely attributable to WMGHGs, whereas global scattering sulfate aerosols would have negligible impacts. Aerosol–cloud interactions appear to have minimal impacts on Mediterranean precipitation in these models, at least in part because many simulations did not fully include such processes; these merit further study. The findings from this study suggest that future BC and WMGHG emissions may significantly affect regional water resources, agricultural practices, ecosystems and

  1. Duodenal perforation precipitated by scrub typhus

    Directory of Open Access Journals (Sweden)

    Raghunath Rajat

    2015-01-01

    Full Text Available Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical exploration. We report the case of a patient with no previous symptoms or risk factors for a duodenal ulcer, who presented with an acute duodenal perforation, probably precipitated by scrub typhus infection.

  2. Modeling the Bergeron-Findeisen Process Using PDF Methods With an Explicit Representation of Mixing

    Science.gov (United States)

    Jeffery, C.; Reisner, J.

    2005-12-01

    Currently, the accurate prediction of cloud droplet and ice crystal number concentration in cloud resolving, numerical weather prediction and climate models is a formidable challenge. The Bergeron-Findeisen process in which ice crystals grow by vapor deposition at the expense of super-cooled droplets is expected to be inhomogeneous in nature--some droplets will evaporate completely in centimeter-scale filaments of sub-saturated air during turbulent mixing while others remain unchanged [Baker et al., QJRMS, 1980]--and is unresolved at even cloud-resolving scales. Despite the large body of observational evidence in support of the inhomogeneous mixing process affecting cloud droplet number [most recently, Brenguier et al., JAS, 2000], it is poorly understood and has yet to be parameterized and incorporated into a numerical model. In this talk, we investigate the Bergeron-Findeisen process using a new approach based on simulations of the probability density function (PDF) of relative humidity during turbulent mixing. PDF methods offer a key advantage over Eulerian (spatial) models of cloud mixing and evaporation: the low probability (cm-scale) filaments of entrained air are explicitly resolved (in probability space) during the mixing event even though their spatial shape, size and location remain unknown. Our PDF approach reveals the following features of the inhomogeneous mixing process during the isobaric turbulent mixing of two parcels containing super-cooled water and ice, respectively: (1) The scavenging of super-cooled droplets is inhomogeneous in nature; some droplets evaporate completely at early times while others remain unchanged. (2) The degree of total droplet evaporation during the initial mixing period depends linearly on the mixing fractions of the two parcels and logarithmically on Damköhler number (Da)---the ratio of turbulent to evaporative time-scales. (3) Our simulations predict that the PDF of Lagrangian (time-integrated) subsaturation (S) goes as

  3. Tritium Level in Romanian Precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Varlam, C.; Stefanescu, I.; Faurescu, I.; Bogdan, D.; Soare, A. [Institute for Cryogenic and Isotope Technologies, Rm. Valcea (Romania); Duliu, O. G. [Faculty of Physics, University of Bucharest, Magurele (Romania)

    2013-07-15

    Romania is one of the countries that has no station included in GNIP (Global Network of Isotopes in Precipitation) on its territory. This paper presents results regarding the tritium concentration in precipitation for the period 1999-2009. The precipitation fell at the Institute for cryogenic and Isotope technologies (geographical coordinates: altitude 237 m, latitude 45{sup o}02'07' N, longitude 24{sup o}17'03' E) an was collected both individually and as a composite average of each month. It was individually measured and the average was calculated and compared with the tritium concentration measured in the composite sample. tritium concentration levels ranged from 9.9 {+-} 2.1 TU for 2004 and 13.7 {+-} 2.2 TU for 2009. Comparing the arithmetic mean values with the weighted mean for the period of observation, it was noticed that the higher absolute values of the weighted means were constant. It was found that for the calculated monthly average for the period of observation (1999-2009), the months with the maximum tritium concentration are the same as the months with the maximum amount of precipitation. This behaviour is typical for the monitored location. (author)

  4. Precipitation scavenging of aerosol particles

    International Nuclear Information System (INIS)

    Radke, L.F.; Eltgroth, M.W.; Hobbs, P.V.

    1978-01-01

    The paper presents the results of precipitation scavenging measurements of particles in the atmosphere and in plumes which were obtained using an airborne measuring system. Attention is given to the so-called 'Greenfield gap' and collection efficiencies for submicron particles

  5. Third generation capture system: precipitating amino acid solvent systems

    NARCIS (Netherlands)

    Sanchez Fernandez, E.; Misiak, K.; Ham, L. van der; Goetheer, E.L.V.

    2013-01-01

    This work summarises the results of the design of novel separation processes for CO2 removal from flue gas based on precipitating amino acid solvents. The processes here described (DECAB, DECAB Plus and pH-swing) use a combination of enhanced CO2 absorption (based on the Le Chatelier’s principle)

  6. The use of simultaneous chemical precipitation in modified activated ...

    African Journals Online (AJOL)

    The IAWQ Activated Sludge Model (ASM) No. 2 is a kinetic-based model and incorporates two simple processes for chemical precipitation and redissolution that are readily integrated with biological processes for carbon, nitrogen and phosphorus removal. This model was applied to experimental data collected as part of this ...

  7. Supercritical antisolvent co-precipitation of rifampicin and ethyl cellulose.

    Science.gov (United States)

    Djerafi, Rania; Swanepoel, Andri; Crampon, Christelle; Kalombo, Lonji; Labuschagne, Philip; Badens, Elisabeth; Masmoudi, Yasmine

    2017-05-01

    Rifampicin-loaded submicron-sized particles were prepared through supercritical anti-solvent process using ethyl cellulose as polymeric encapsulating excipient. Ethyl acetate and a mixture of ethyl acetate/dimethyl sulfoxide (70/30 and 85/15) were used as solvents for both drug and polymeric excipient. When ethyl acetate was used, rifampicin was crystallized separately without being embedded within the ethyl cellulose matrix while by using the ethyl acetate/dimethyl sulfoxide mixture, reduced crystallinity of the active ingredient was observed and a simultaneous precipitation of ethyl cellulose and drug was achieved. The effect of solvent/CO 2 molar ratio and polymer/drug mass ratio on the co-precipitates morphology and drug loading was investigated. Using the solvent mixture, co-precipitates with particle sizes ranging between 190 and 230nm were obtained with drug loading and drug precipitation yield from respectively 8.5 to 38.5 and 42.4 to 77.2% when decreasing the ethyl cellulose/rifampicin ratio. Results show that the solvent nature and the initial drug concentrations affect morphology and drug precipitation yield of the formulations. In vitro dissolution studies revealed that the release profile of rifampicin was sustained when co-precipitation was carried out with the solvent mixture. It was demonstrated that the drug to polymer ratio influenced amorphous content of the SAS co-precipitates. Differential scanning calorimetry thermograms and infrared spectra revealed that there is neither interaction between rifampicin and the polymer nor degradation of rifampicin during co-precipitation. In addition, stability stress tests on SAS co-precipitates were carried out at 75% relative humidity and room temperature in order to evaluate their physical stability. SAS co-precipitates were X-ray amorphous and remained stable after 6months of storage. The SAS co-precipitation process using a mixture of ethyl acetate/dimethyl sulfoxide demonstrates that this strategy can

  8. Heating-insensitive scale increase caused by convective precipitation

    Science.gov (United States)

    Haerter, Jan; Moseley, Christopher; Berg, Peter

    2017-04-01

    The origin of intense convective extremes and their unusual temperature dependence has recently challenged traditional thermodynamic arguments, based on the Clausius-Clapeyron relation. In a sequence of studies (Lenderink and v. Mejgaard, Nat Geosc, 2008; Berg, Haerter, Moseley, Nat Geosc, 2013; and Moseley, Hohenegger, Berg, Haerter, Nat Geosc, 2016) the argument of convective-type precipitation overcoming the 7%/K increase in extremes by dynamical, rather than thermodynamic, processes has been promoted. How can the role of dynamical processes be approached for precipitating convective cloud? One-phase, non-precipitating Rayleigh-Bénard convection is a classical problem in complex systems science. When a fluid between two horizontal plates is sufficiently heated from below, convective rolls spontaneously form. In shallow, non-precipitating atmospheric convection, rolls are also known to form under specific conditions, with horizontal scales roughly proportional to the boundary layer height. Here we explore within idealized large-eddy simulations, how the scale of convection is modified, when precipitation sets in and intensifies in the course of diurnal solar heating. Before onset of precipitation, Bénard cells with relatively constant diameter form, roughly on the scale of the atmospheric boundary layer. We find that the onset of precipitation then signals an approximately linear (in time) increase in horizontal scale. This scale increase progresses at a speed which is rather insensitive to changes in surface temperature or changes in the rate at which boundary conditions change, hinting at spatial characteristics, rather than temperature, as a possible control on spatial scales of convection. When exploring the depth of spatial correlations, we find that precipitation onset causes a sudden disruption of order and a subsequent complete disintegration of organization —until precipitation eventually ceases. Returning to the initial question of convective

  9. Investigation of Varied Strontium-Transuranic Precipitation Chemistries for Crossflow

    International Nuclear Information System (INIS)

    Nash, C.A.

    2000-01-01

    Precipitation chemistries for strontium and transuranic (TRU) removal have been tested for crossflow filterability and lanthanide removal with simulants of Hanford tank 241-AN-107 supernate. This is the initial work indicating the usefulness of a strontium and permanganate precipitation process as applied to the Hanford River Protection Project. Precipitations with both ferric and ferrous iron were shown to be at least two orders of magnitude less filterable than a 0.1 gpm/ft target average flux that was desired at the time. A precipitate from a strontium nitrate strike alone was found to filter easily and to make the desired average flux. Other chemistries tested included precipitant of lanthanum(III), nickel (II), calcium (II), and a redox chemistry using sodium permanganate. Of these chemistries a strontium and permanganate strike including calcium provided the highest filter flux compared to the other chemistries. It showed the most promise in lanthanide removal as well. This work provides a promising direction for further work to achieve both acceptable filterability and decontamination for Envelope C wastes to be treated by the Hanford River Protection Project. The work reported here was originally intended to satisfy needs for crossflow filter testing of a strontium and ferric precipitation method for treating Envelope C using a 241-AN-107 simulant

  10. Using NDVI to measure precipitation in semi-arid landscapes

    Science.gov (United States)

    Birtwhistle, Amy N.; Laituri, Melinda; Bledsoe, Brian; Friedman, Jonathan M.

    2016-01-01

    Measuring precipitation in semi-arid landscapes is important for understanding the processes related to rainfall and run-off; however, measuring precipitation accurately can often be challenging especially within remote regions where precipitation instruments are scarce. Typically, rain-gauges are sparsely distributed and research comparing rain-gauge and RADAR precipitation estimates reveal that RADAR data are often misleading, especially for monsoon season convective storms. This study investigates an alternative way to map the spatial and temporal variation of precipitation inputs along ephemeral stream channels using Normalized Difference Vegetation Index (NDVI) derived from Landsat Thematic Mapper imagery. NDVI values from 26 years of pre- and post-monsoon season Landsat imagery were derived across Yuma Proving Ground (YPG), a region covering 3,367 km2 of semiarid landscapes in southwestern Arizona, USA. The change in NDVI from a pre-to post-monsoon season image along ephemeral stream channels explained 73% of the variance in annual monsoonal precipitation totals from a nearby rain-gauge. In addition, large seasonal changes in NDVI along channels were useful in determining when and where flow events have occurred.

  11. Investigation of Varied Strontium-Transuranic Precipitation Chemistries for Crossflow

    Energy Technology Data Exchange (ETDEWEB)

    Nash, C.A.

    2000-07-27

    Precipitation chemistries for strontium and transuranic (TRU) removal have been tested for crossflow filterability and lanthanide removal with simulants of Hanford tank 241-AN-107 supernate. This is the initial work indicating the usefulness of a strontium and permanganate precipitation process as applied to the Hanford River Protection Project. Precipitations with both ferric and ferrous iron were shown to be at least two orders of magnitude less filterable than a 0.1 gpm/ft target average flux that was desired at the time. A precipitate from a strontium nitrate strike alone was found to filter easily and to make the desired average flux. Other chemistries tested included precipitant of lanthanum(III), nickel (II), calcium (II), and a redox chemistry using sodium permanganate. Of these chemistries a strontium and permanganate strike including calcium provided the highest filter flux compared to the other chemistries. It showed the most promise in lanthanide removal as well. This work provides a promising direction for further work to achieve both acceptable filterability and decontamination for Envelope C wastes to be treated by the Hanford River Protection Project. The work reported here was originally intended to satisfy needs for crossflow filter testing of a strontium and ferric precipitation method for treating Envelope C using a 241-AN-107 simulant.

  12. a Study of Oxygen Precipitation in Heavily Doped Silicon.

    Science.gov (United States)

    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

  13. Acid precipitation; an annotated bibliography

    Science.gov (United States)

    Wiltshire, Denise A.; Evans, Margaret L.

    1984-01-01

    This collection of 1660 bibliographies references on the causes and environmental effects of acidic atmospheric deposition was compiled from computerized literature searches of earth-science and chemistry data bases. Categories of information are (1) atmospheric chemistry (gases and aerosols), (2) precipitation chemistry, (3) transport and deposition (wet and dry), (4) aquatic environments (biological and hydrological), (5) terrestrial environments, (6) effects on materials and structures, (7) air and precipitation monitoring and data collection, and (8) modeling studies. References date from the late 1800 's through December 1981. The bibliography includes short summaries of most documents. Omitted are unpublished manuscripts, publications in press, master 's theses and doctoral dissertations, newspaper articles, and book reviews. Coauthors and subject indexes are included. (USGS)

  14. Isotopic composition of past precipitation

    International Nuclear Information System (INIS)

    Edwards, T.W.D.

    1998-01-01

    The distribution of stable isotopes in precipitation provides critical quantitative information about the global water cycle. The first PAGES/IAEA ISOMAP workshop was held at the IAEA headquarters in Vienna, 24-26 August 1998, which gathered 32 participants. The presentation and discussions demonstrated that a high level of sophistication already exists in the development of transfer functions between measured parameters and precipitation, as a result of the extensive use of water isotope tracers in paleo-environmental investigations, but a major challenge facing both producers and users of paleo-isotope data is the effective management of data and meta-data, to permit ready retrieval of raw and inferred data for comparison and reinterpretation. This will be in important goal of future ISOMAP activities. The critical need for more paleo-data from low latitudes was clearly recognized

  15. Precipitation-Static-Reduction Research

    Science.gov (United States)

    1943-03-31

    if» 85 z \\ PRECIPITATION-STATIC-REDUCTION RESEARCH study of the effects of flame length , flame spacing, and burner spacing on B shows that there...unod: Flame length *. The visual length of the flame from the burner tip to the flame tip when examined in a darkened room against a black background...Postlve and Negative Flames The use of the second flame-conduction coefficient, B, facilitates considerably the study of the effect of flame length , spacing

  16. Phase characterization of precipitated zirconia

    International Nuclear Information System (INIS)

    Gutzov, S.; Ponahlo, J.; Lengauer, C.L.; Beran, A.

    1994-01-01

    The phase compositions of undoped and europium-doped zirconia samples, obtained by precipitation and thermal treatment from 350 to 1,000 C, have been investigated by powder X-ray diffractometry, infrared spectroscopy, and cathodoluminescence spectroscopy. The low-temperature stabilization of tetragonal zirconia is mainly controlled by the presence of anion additives, such as ammonium chloride. The influences of the crystallite size is less important. Cathodoluminescence spectra show a structural similarity between tetragonal and amorphous zirconia

  17. Pushing precipitation to the extremes in distributed experiments: Recommendations for simulating wet and dry years

    Science.gov (United States)

    Knapp, Alan K.; Avolio, Meghan L.; Beier, Claus; Carroll, Charles J.W.; Collins, Scott L.; Dukes, Jeffrey S.; Fraser, Lauchlan H.; Griffin-Nolan, Robert J.; Hoover, David L.; Jentsch, Anke; Loik, Michael E.; Phillips, Richard P.; Post, Alison K.; Sala, Osvaldo E.; Slette, Ingrid J.; Yahdjian, Laura; Smith, Melinda D.

    2017-01-01

    on each site's past climatic characteristics. This approach, though not often used by ecologists, allows ecological responses to be directly compared across disparate ecosystems and climates, facilitating process-level understanding of ecosystem sensitivity to precipitation extremes.

  18. Investigating precipitation changes of anthropic origin: data and methodological issues

    Science.gov (United States)

    de Lima, Isabel; Lovejoy, Shaun

    2017-04-01

    There is much concern about the social, environmental and economic impacts of climate change that could result directly from changes in temperature and precipitation. For temperature, the situation is better understood; but despite the many studies that have been already dedicated to precipitation, change in this process - that could be associated to the transition to the Anthropocene - has not yet been convincingly proven. A large fraction of those studies have been exploring temporal (linear) trends in local precipitation, sometimes using records over only a few decades; other fewer studies have been dedicated to investigating global precipitation change. Overall, precipitation change of anthropic origin has showed to be difficult to establish with high statistical significance and, moreover, different data and products have displayed important discrepancies; this is valid even for global precipitation. We argue that the inadequate resolution and length of the data commonly used, as well as methodological issues, are among the main factors limiting the ability to identify the signature of change in precipitation. We propose several ways in which one can hope to improve the situation - or at least - clarify the difficulties. From the point of view of statistical analysis, the problem is one of detecting a low frequency anthropogenic signal in the presence of "noise" - the natural variability (the latter includes both internal dynamics and responses to volcanic, solar or other natural forcings). A consequence is that as one moves to longer and longer time scales, fluctuations are increasingly averaged and at some point, the anthropogenic signal will stand out above the natural variability noise. This approach can be systematized using scaling fluctuation analysis to characterizing different precipitation scaling regimes: weather, macroweather, climate - from higher to lower frequencies; in the anthropocene, the macroweather regime covers the range of time scales

  19. Ceria powders by homogeneous precipitation technique

    International Nuclear Information System (INIS)

    Ramanathan, S.; Roy, S.K.

    2003-01-01

    Formation of precursors for ceria by two homogeneous precipitation reactions - (cerium chloride + urea at 95 degC - called reaction A and cerium chloride + hexamethylenetetramine at 85 degC - called reaction B) - has been studied. The variation of size of the colloidal particles formed and the zeta potential of the suspensions with progress of reactions exhibited similar trends for both the precipitation processes. Particle size increased from 100 to 300 nm with increasing temperature and extent of reaction. The zeta potential was found to decrease with increasing extent of precipitation in the pH range of 5 to 7. Filtration and drying led to agglomeration of the fine particles in case of the precursor from reaction B. The as-formed precursors were crystalline - a basic carbonate in case of reaction A and hydrous oxide in case of reaction B. It was found that nano-crystalline ceria powders (average crystallite size -10 nm) formed above 400 degC from both these precursors. The agglomerate size (D50) of the precursors and ceria powders formed after calcination at 600 degC varied from 0.7 to 3 μm. Increasing calcination temperature up to 800 degC, increased the crystallite size (50 nm). The zeta potential variation with pH and concentration of an anionic dispersant (Calgon) for the ceria powders formed was studied to determine the ideal conditions for suspension stability. It was found to be maximum (i.e., the suspensions stable) in the pH range of 3 to 4 or Calgon concentration of 0.01 to 0.1 weight percent. (author)

  20. U.S. 15 Minute Precipitation Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. 15 Minute Precipitation Data is digital data set DSI-3260, archived at the National Climatic Data Center (NCDC). This is precipitation data. The primary source...

  1. European climate change experiments on precipitation change

    DEFF Research Database (Denmark)

    Beier, Claus

    Presentation of European activities and networks related to experiments and databases within precipitation change......Presentation of European activities and networks related to experiments and databases within precipitation change...

  2. Amazon River Basin Precipitation, 1972-1992

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: The precipitation data is 0.2 degree gridded monthly precipitation data based upon monthly rain data from Peru and Bolivia and daily rain data from Brazil....

  3. A new technique for production of yellow cake with double precipitation

    International Nuclear Information System (INIS)

    Li Jianhua; Zeng Yijun; Li Shangyuan; Kong Guiying

    1997-01-01

    The author presents a new technique for production of yellow cake with double precipitation, thus solving a series of problems for precipitating uranium with traditional double precipitation. The new technique can not only remove ferric ions and sulfate radicals but also make solid-liquid separation easy, utilize effectively the sulfuric acid produced in ferric ions precipitation process, and increase uranium concentration of leaching liquor. To take it as producing yellow cake will save investment, simplify operation, and cut down the consumption of raw materials and energies. It is more competitive than ion-exchange or solvent extraction in the process of extracting-purifying and preparing yellow cake

  4. Toward Seamless Weather-Climate Prediction with a Global Cloud Resolving Model

    Science.gov (United States)

    2016-01-14

    PAGE 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON Tim Li 19b. TELEPHONE NUMBER (Include area code) 808...The coupled model initial condition was derived based on a nudging scheme in which the model prognostic variables such as U, V, SLP, geopotential...height, air temperature and SST were nudged toward NCEP final analysis (FNL) fields. There were 24 ensemble forecast members each day. TCs in the model

  5. Advances towards the development of a cloud-resolving model in South Africa

    CSIR Research Space (South Africa)

    Bopape, Mary-Jane M

    2014-09-01

    Full Text Available , Nelson A.F. Miranda , Rosemary A. Dorrington , Gwynneth F. Matcher , Nadine Strydom & Nasreen Peer .............................................................................................. 89 Open access in South Africa: A case study... and slows scientific progress.5 There are also more radical and, at the same time, very human positions on the importance of open access. Delivering an address entitled ‘The case against privatising knowledge’, during a Vice Chancellor’s Open Lecture...

  6. A Bulk Microphysics Parameterization with Multiple Ice Precipitation Categories.

    Science.gov (United States)

    Straka, Jerry M.; Mansell, Edward R.

    2005-04-01

    A single-moment bulk microphysics scheme with multiple ice precipitation categories is described. It has 2 liquid hydrometeor categories (cloud droplets and rain) and 10 ice categories that are characterized by habit, size, and density—two ice crystal habits (column and plate), rimed cloud ice, snow (ice crystal aggregates), three categories of graupel with different densities and intercepts, frozen drops, small hail, and large hail. The concept of riming history is implemented for conversions among the graupel and frozen drops categories. The multiple precipitation ice categories allow a range of particle densities and fall velocities for simulating a variety of convective storms with minimal parameter tuning. The scheme is applied to two cases—an idealized continental multicell storm that demonstrates the ice precipitation process, and a small Florida maritime storm in which the warm rain process is important.

  7. Bias correction of daily satellite precipitation data using genetic algorithm

    Science.gov (United States)

    Pratama, A. W.; Buono, A.; Hidayat, R.; Harsa, H.

    2018-05-01

    Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS) was producted by blending Satellite-only Climate Hazards Group InfraRed Precipitation (CHIRP) with Stasion observations data. The blending process was aimed to reduce bias of CHIRP. However, Biases of CHIRPS on statistical moment and quantil values were high during wet season over Java Island. This paper presented a bias correction scheme to adjust statistical moment of CHIRP using observation precipitation data. The scheme combined Genetic Algorithm and Nonlinear Power Transformation, the results was evaluated based on different season and different elevation level. The experiment results revealed that the scheme robustly reduced bias on variance around 100% reduction and leaded to reduction of first, and second quantile biases. However, bias on third quantile only reduced during dry months. Based on different level of elevation, the performance of bias correction process is only significantly different on skewness indicators.

  8. Importance of resolution and model configuration when downscaling extreme precipitation

    Directory of Open Access Journals (Sweden)

    Adrian J. Champion

    2014-07-01

    Full Text Available Dynamical downscaling is frequently used to investigate the dynamical variables of extra-tropical cyclones, for example, precipitation, using very high-resolution models nested within coarser resolution models to understand the processes that lead to intense precipitation. It is also used in climate change studies, using long timeseries to investigate trends in precipitation, or to look at the small-scale dynamical processes for specific case studies. This study investigates some of the problems associated with dynamical downscaling and looks at the optimum configuration to obtain the distribution and intensity of a precipitation field to match observations. This study uses the Met Office Unified Model run in limited area mode with grid spacings of 12, 4 and 1.5 km, driven by boundary conditions provided by the ECMWF Operational Analysis to produce high-resolution simulations for the Summer of 2007 UK flooding events. The numerical weather prediction model is initiated at varying times before the peak precipitation is observed to test the importance of the initialisation and boundary conditions, and how long the simulation can be run for. The results are compared to raingauge data as verification and show that the model intensities are most similar to observations when the model is initialised 12 hours before the peak precipitation is observed. It was also shown that using non-gridded datasets makes verification more difficult, with the density of observations also affecting the intensities observed. It is concluded that the simulations are able to produce realistic precipitation intensities when driven by the coarser resolution data.

  9. Spatial interpolation schemes of daily precipitation for hydrologic modeling

    Science.gov (United States)

    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.

  10. Precipitation variability assessment of northeast China: Songhua ...

    Indian Academy of Sciences (India)

    Variability in precipitation is critical for the management of water resources. ... applied on precipitation data on a monthly, seasonally, annually, decade scale and the number of rainy ... 2015). As a result, such irregularities in precipitation,. i.e., droughts and floods can affect the ... (January–December), years and decades.

  11. Effect of Aqueous Media on the Recovery of Scandium by Selective Precipitation

    Directory of Open Access Journals (Sweden)

    Bengi Yagmurlu

    2018-05-01

    Full Text Available This research presents a novel precipitation method for scandium (Sc concentrate refining from bauxite residue leachates and the effect of aqueous media on this triple-stage successive precipitation process. The precipitation pattern and the precipitation behavior of the constituent elements was investigated using different precipitation agents in three major mineral acid media, namely, H2SO4, HNO3, and HCl in a comparative manner. Experimental investigations showed behavioral similarities between HNO3 and HCl media, while H2SO4 media was different from them because of the nature of the formed complexes. NH4OH was found to be the best precipitation agent in every leaching media to remove Fe(III with low Sc co-precipitation. To limit Sc loss from the system, Fe(III removal was divided into two steps, leading to more than 90% of Fe(III removal at the end of the process. Phosphate concentrates were produced in the final step of the precipitation process with dibasic phosphates which have a strong affinity towards Sc. Concentrates containing more than 50% of ScPO4 were produced in each case from the solutions after Fe(III removal, as described. A flow diagram of the selective precipitation process is proposed for these three mineral acid media with their characteristic parameters.

  12. Precipitation stripping of neodymium from carboxylate extractant with aqueous oxalic acid solutions

    International Nuclear Information System (INIS)

    Konishi, Yasuhiro; Asai, Satoru; Murai, Tetuya

    1993-01-01

    This paper describes a precipitation stripping method in which neodymium ions are stripped from carboxylate extractant in organic solvent and simultaneously precipitated with aqueous oxalic acid solution. For the single-stage process, a quantitative criterion for precipitating oxalate powders was derived theoretically, and stripping experiments were done under the precipitation conditions. The resultant precipitates were neodymium oxalate, which is completely free from contamination by the carboxylate extractant and the organic solvent. The overall rate of stripping was controlled by the transfer of neodymium carboxylate in the organic solution, indicating that the presence of oxalic acid in the aqueous phase has no effect on the stripping rate. These findings demonstrate the feasibility of combining the conventional stripping and precipitation stages in a solvent extraction process for separation and purification of rare earths

  13. Stability and precipitation of diverse nanoparticles

    Science.gov (United States)

    Desai, Chintal

    nanotubes. Formation of colloidal dispersions via precipitation processes has been widely used in the chemical and pharmaceutical industries. The synthesis of micro- particles for hydrophobic drugs is effectively carried out via anti-solvent precipitation method. The formation of small particles in the precipitation method is strongly influenced by colloidal interactions, and therefore, dependent on the properties of the particles and the liquid. The effect of solvent on the colloidal stability of the micro-drug particles is studied in detail. It is found that the organic solvent plays an important role on particle formation, polymorphism and stability of micron scale drug particles in aqueous media. Also, the supersaturation can be varied by using different solvents and the physicochemical characteristics of the suspension can be altered, which affects stability. Understanding of the colloidal stability and the aggregation kinetics has great importance not only for fundamental researches, but also for their applications.

  14. Analyzing coastal precipitation using TRMM observations

    Directory of Open Access Journals (Sweden)

    R. H. Heiblum

    2011-12-01

    Full Text Available The interaction between breezes and synoptic gradient winds, and surface friction increase in transition from sea to land can create persistent convergence zones nearby coastlines. The low level convergence of moist air promotes the dynamical and microphysical processes responsible for the formation of clouds and precipitation.

    Our work focuses on the winter seasons of 1998–2011 in the Eastern Mediterranean. During the winter the Mediterranean sea is usually warmer than the adjacent land, resulting in frequent occurrence of land breeze that opposes the common synoptic winds. Using rain-rate vertical profiles from the Tropical Rainfall Measurement Mission (TRMM satellite, we examined the spatial and temporal distribution of average hydrometeor mass in clouds as a function of the distance from coastlines.

    Results show that coastlines in the Eastern Mediterranean are indeed favored areas for precipitation formation. The intra-seasonal and diurnal changes in the distribution of hydrometeor mass indicate that the land breeze may likely be the main responsible mechanism behind our results.

  15. Decomposition of oxalate precipitates by photochemical reaction

    International Nuclear Information System (INIS)

    Jae-Hyung Yoo; Eung-Ho Kim

    1999-01-01

    A photo-radiation method was applied to decompose oxalate precipitates so that it can be dissolved into dilute nitric acid. This work has been studied as a part of partitioning of minor actinides. Minor actinides can be recovered from high-level wastes as oxalate precipitates, but they tend to be coprecipitated together with lanthanide oxalates. This requires another partitioning step for mutual separation of actinide and lanthanide groups. In this study, therefore, some experimental work of photochemical decomposition of oxalate was carried out to prove its feasibility as a step of partitioning process. The decomposition of oxalic acid in the presence of nitric acid was performed in advance in order to understand the mechanistic behaviour of oxalate destruction, and then the decomposition of neodymium oxalate, which was chosen as a stand-in compound representing minor actinide and lanthanide oxalates, was examined. The decomposition rate of neodymium oxalate was found as 0.003 mole/hr at the conditions of 0.5 M HNO 3 and room temperature when a mercury lamp was used as a light source. (author)

  16. Variability of multifractal parameters in an urban precipitation monitoring network

    Science.gov (United States)

    Licznar, Paweł; De Michele, Carlo; Dżugaj, Dagmara; Niesobska, Maria

    2014-05-01

    Precipitation especially over urban areas is considered a highly non-linear process, with wide variability over a broad range of temporal and spatial scales. Despite obvious limitations of rainfall gauges location at urban sites, rainfall monitoring by gauge networks is a standard solution of urban hydrology. Often urban precipitation gauge networks are formed by modern electronic gauges and connected to control units of centralized urban drainage systems. Precipitation data, recorded online through these gauge networks, are used in so called Real-Time-Control (RTC) systems for the development of optimal strategies of urban drainage outflows management. As a matter of fact, the operation of RTC systems is motivated mainly by the urge of reducing the severity of urban floods and combined sewerage overflows, but at the same time, it creates new valuable precipitation data sources. The variability of precipitation process could be achieved by investigating multifractal behavior displayed by the temporal structure of precipitation data. There are multiply scientific communications concerning multifractal properties of point-rainfall data from different worldwide locations. However, very little is known about the close variability of multifractal parameters among closely located gauges, at the distances of single kilometers. Having this in mind, here we assess the variability of multifractal parameters among gauges of the urban precipitation monitoring network in Warsaw, Poland. We base our analysis on the set of 1-minute rainfall time series recorded in the period 2008-2011 by 25 electronic weighing type gauges deployed around the city by the Municipal Water Supply and Sewerage Company in Warsaw as a part of local RTC system. The presence of scale invariance and multifractal properties in the precipitation process was investigated with spectral analysis, functional box counting method and studying the probability distributions and statistical moments of the rainfall

  17. Precipitation interpolation in mountainous areas

    Science.gov (United States)

    Kolberg, Sjur

    2015-04-01

    Different precipitation interpolation techniques as well as external drift covariates are tested and compared in a 26000 km2 mountainous area in Norway, using daily data from 60 stations. The main method of assessment is cross-validation. Annual precipitation in the area varies from below 500 mm to more than 2000 mm. The data were corrected for wind-driven undercatch according to operational standards. While temporal evaluation produce seemingly acceptable at-station correlation values (on average around 0.6), the average daily spatial correlation is less than 0.1. Penalising also bias, Nash-Sutcliffe R2 values are negative for spatial correspondence, and around 0.15 for temporal. Despite largely violated assumptions, plain Kriging produces better results than simple inverse distance weighting. More surprisingly, the presumably 'worst-case' benchmark of no interpolation at all, simply averaging all 60 stations for each day, actually outperformed the standard interpolation techniques. For logistic reasons, high altitudes are under-represented in the gauge network. The possible effect of this was investigated by a) fitting a precipitation lapse rate as an external drift, and b) applying a linear model of orographic enhancement (Smith and Barstad, 2004). These techniques improved the results only marginally. The gauge density in the region is one for each 433 km2; higher than the overall density of the Norwegian national network. Admittedly the cross-validation technique reduces the gauge density, still the results suggest that we are far from able to provide hydrological models with adequate data for the main driving force.

  18. Radiation Induced Precipitation in Iron

    Energy Technology Data Exchange (ETDEWEB)

    Solly, B

    1964-02-15

    Foils of iron have been neutron-irradiated in the Swedish re- search reactor R2 to integrated doses in the range 10{sup 17} - 10{sup 19} nvt (> 1 MeV) and examined by transmission electron microscopy. Features have been observed having diffraction contrast similar to that of the prismatic dislocation loops formed in f.c.c. metals by the collapse of point-defect clusters. The features have been shown to be due to precipitation of impurities at radiation damage centres in the iron matrix.

  19. Recent Developments on Discontinuous Precipitation

    Directory of Open Access Journals (Sweden)

    Zięba P.

    2017-06-01

    Full Text Available The discontinuous precipitation (DP belongs to a group of diffusive solid state phase transformations during which the formation of a new phase is heterogeneous and limited to a migrating reaction front (RF. The use of analytical electron microscopy provided reliable information that there is no differences in the diffusion rate at the stationary grain boundary and moving RF of DP reaction. On the other hand, the use of “in situ” transmission electron microscopy observations indicated the importance of stop-go motion or oscillatory movement of the RF.

  20. Radiation Induced Precipitation in Iron

    International Nuclear Information System (INIS)

    Solly, B.

    1964-02-01

    Foils of iron have been neutron-irradiated in the Swedish re- search reactor R2 to integrated doses in the range 10 17 - 10 19 nvt (> 1 MeV) and examined by transmission electron microscopy. Features have been observed having diffraction contrast similar to that of the prismatic dislocation loops formed in f.c.c. metals by the collapse of point-defect clusters. The features have been shown to be due to precipitation of impurities at radiation damage centres in the iron matrix

  1. Influence of cobalt and chromium additions on the precipitation processes in a Cu-4Ti alloys; Influencia de la adicion de cobalto y cromo en el proceso de precipitacion en una aleacion de Cu-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, E.

    2010-07-01

    The influence of 0.5% atomic cobalt and 1% atomic chromium additions on the precipitation hardening of Cu-4Ti alloy was studied by differential scanning calorimetry (DSC) and microhardness measurements. The analysis of the calorimetric curves, for binary alloy, shows the presence of two overlapping exothermic reactions (stages 1 and 2) attributed to the formation of Cu{sub 4}Ti and Cu{sub 3}Ti particles in the copper matrix, respectively. DSC curves for Cu-4Ti-0.5Co alloy shows three exothermic effects (overlapping stages 3 and 4 and stage 5) associated to the formation of phases Ti{sub 2}Co, TiCo and Cu{sub 4}Ti, respectively. DSC curves for Cu-4Ti1Cr alloy shows three exothermic reactions (stages 6, 7 and 9) and one endothermic peak (stage 8). The exothermic reactions correspond to the formation of phases Cr{sub 2}Ti, Cu{sub 4}Ti and Cu{sub 3}Ti, respectively, and the endothermic reactions are attributed to the Cr{sub 2}Ti dissolution. The activation energies calculated using the modified Kissinger method were lower than the ones corresponding to diffusion of cobalt, chromium, and titanium in copper. Kinetic parameters were obtained by a convolution method based on the Johnson-Mehl-Avrami (JMA) formalism. Microhardness measurements confirmed the formation of the mentioned phases. Also, these measurements confirmed the effect of cobalt and chromium addition on the binary alloy hardness. (Author). 31 refs.

  2. Evaluation of ERA-Interim precipitation data in complex terrain

    Science.gov (United States)

    Gao, Lu; Bernhardt, Matthias; Schulz, Karsten

    2013-04-01

    Precipitation controls a large variety of environmental processes, which is an essential input parameter for land surface models e.g. in hydrology, ecology and climatology. However, rain gauge networks provides the necessary information, are commonly sparse in complex terrains, especially in high mountainous regions. Reanalysis products (e.g. ERA-40 and NCEP-NCAR) as surrogate data are increasing applied in the past years. Although they are improving forward, previous studies showed that these products should be objectively evaluated due to their various uncertainties. In this study, we evaluated the precipitation data from ERA-Interim, which is a latest reanalysis product developed by ECMWF. ERA-Interim daily total precipitation are compared with high resolution gridded observation dataset (E-OBS) at 0.25°×0.25° grids for the period 1979-2010 over central Alps (45.5-48°N, 6.25-11.5°E). Wet or dry day is defined using different threshold values (0.5mm, 1mm, 5mm, 10mm and 20mm). The correspondence ratio (CR) is applied for frequency comparison, which is the ratio of days when precipitation occurs in both ERA-Interim and E-OBS dataset. The result shows that ERA-Interim captures precipitation occurrence very well with a range of CR from 0.80 to 0.97 for 0.5mm to 20mm thresholds. However, the bias of intensity increases with rising thresholds. Mean absolute error (MAE) varies between 4.5 mm day-1 and 9.5 mm day-1 in wet days for whole area. In term of mean annual cycle, ERA-Interim almost has the same standard deviation of the interannual variability of daily precipitation with E-OBS, 1.0 mm day-1. Significant wet biases happened in ERA-Interim throughout warm season (May to August) and dry biases in cold season (November to February). The spatial distribution of mean annual daily precipitation shows that ERA-Interim significant underestimates precipitation intensity in high mountains and northern flank of Alpine chain from November to March while pronounced

  3. Formation and Thermal Stability of Large Precipitates and Oxides in Titanium and Niobium Microalloyed Steel

    Institute of Scientific and Technical Information of China (English)

    ZHUO Xiao-jun; WOO Dae-hee; WANG Xin-hua; LEE Hae-geon

    2008-01-01

    As-cast CC slabs of microalloyed steels are prone to surface and sub-surface cracking. Precipitation phenomena in-itiated during solidification reduce ductility at high temperature. The unidirectional solidification unit is employed to sim-ulate the solidification process during continuous casting. Precipitation behavior and thermal stability are systemati-cally investigated. Samples of adding titanium and niobium to steels have been examined using field emission scanning electron microscope (FE-SEM), electron probe X-ray microanalyzer (EPMA), and transmission electron microscope (TEM). It has been found that the addition of titanium and niobium to high-strength low-alloyed (HSLA) steel resuited in undesirable large precipitation in the steels, i. e. , precipitation of large precipitates with various morphologies. The composition of the large precipitates has been determined. The effect of cooling rate on (Ti, Nb)(C, N) precipitate formation is investigated. With increasing the cooling rate, titanium-rich (Ti,Nb)(C, N) precipitates are transformed to niobium-rich (Ti,Nb)(C,N) precipitates. The thermal stability of these large precipitates and oxides have been assessed by carrying out various heat treatments such as holding and quenching from temperature at 800 and 1 200 ℃. It has been found that titanium-rich (Ti,Nb)(C,N) precipitate is stable at about 1 200 ℃ and niobi-um-rich (Ti,Nb)(C,N) precipitate is stable at about 800 ℃. After reheating at 1 200 ℃ for 1 h, (Ca, Mn)S and TiN are precipitated from Ca-Al oxide. However, during reheating at 800 ℃ for 1 h, Ca-Al-Ti oxide in specimens was stable. The thermodynamic calculation of simulating the thermal process is employed. The calculation results are in good agreement with the experimental results.

  4. The Contribution of Extreme Precipitation to the Total Precipitation in China

    Institute of Scientific and Technical Information of China (English)

    SUN Jian-Qi

    2012-01-01

    Using daily precipitation data from weather stations in China, the variations in the contribution of extreme precipitation to the total precipitation are analyzed. It is found that extreme precipitation accounts for approximately one third of the total precipitation based on the overall mean for China. Over the past half century, extreme precipitation has played a dominant role in the year-to-year variability of the total precipitation. On the decadal time scale, the extreme precipitation makes different contributions to the wetting and drying regions of China. The wetting trends of particular regions are mainly attributed to increases in extreme precipitation; in contrast, the drying trends of other regions are mainly due to decreases in non-extreme precipitation.

  5. Gravity settling of precipitated magnetite and ferric floc

    International Nuclear Information System (INIS)

    Holt, N.S.; Loft, P.R.

    1983-06-01

    A comparison is presented of the gravity settling performance of ferric floc and magnetite, both in batch settling tests, and on a continuous gravity settler. The precipitation of magnetite from solution on a continuous basis was also demonstrated, and the process was shown not to be significantly affected by the presence of a wide range of chemical species. (U.K.)

  6. Precipitation of plutonium (III) oxalate and calcination to plutonium oxide

    International Nuclear Information System (INIS)

    Esteban, A.; Orosco, E.H.; Cassaniti, P.; Greco, L.; Adelfang, P.

    1989-01-01

    The plutonium based fuel fabrication requires the conversion of the plutonium nitrate solution from nuclear fuel reprocessing into pure PuO2. The conversion method based on the precipitation of plutonium (III) oxalate and subsequent calcination has been studied in detail. In this procedure, plutonium (III) oxalate is precipitated, at room temperature, by the slow addition of 1M oxalic acid to the feed solution, containing from 5-100 g/l of plutonium in 1M nitric acid. Before precipitation, the plutonium is adjusted to trivalent state by addition of 1M ascorbic acid in the presence of an oxidation inhibitor such as hydrazine. Finally, the precipitate is calcinated at 700 deg C to obtain PuO2. A flowsheet is proposed in this paper including: a) A study about the conditions to adjust the plutonium valence. b) Solubility data of plutonium (III) oxalate and measurements of plutonium losses to the filtrate and wash solution. c) Characterization of the obtained products. Plutonium (III) oxalate has several potential advantages over similar conversion processes. These include: 1) Formation of small particle sizes powder with good pellets fabrication characteristics. 2) The process is rather insensitive to most process variables, except nitric acid concentration. 3) Ambient temperature operations. 4) The losses of plutonium to the filtrate are less than in other conversion processes. (Author) [es

  7. A glacier runoff extension to the Precipitation Runoff Modeling System

    Science.gov (United States)

    A. E. Van Beusekom; R. J. Viger

    2016-01-01

    A module to simulate glacier runoff, PRMSglacier, was added to PRMS (Precipitation Runoff Modeling System), a distributed-parameter, physical-process hydrological simulation code. The extension does not require extensive on-glacier measurements or computational expense but still relies on physical principles over empirical relations as much as is feasible while...

  8. Use of biogenic sulfide for ZnS precipitation

    NARCIS (Netherlands)

    Esposito, G.; Veeken, A.; Weijma, J.; Lens, P.N.L.

    2006-01-01

    A 600 ml continuously stirred tank reactor was used to assess the performance of a zinc sulfide precipitation process using a biogenic sulfide solution (the effluent of a sulfate-reducing bioreactor) as sulfide source. In all experiments, a proportional-integral (PI) control algorithm was used to

  9. Fundamental chemistry of precipitation and mineral scale formation

    Science.gov (United States)

    Alan W. Rudie; Peter W. Hart

    2005-01-01

    The mineral scale that deposits in digesters and bleach plants is formed by a chemical precipitation process. As such, it is accurately described or modeled using the solubility product equilibrium constant. Although solubility product identifies the primary conditions that need to be met for a scale problem to exist, the acid base equilibria of the scaling anions...

  10. Estimating Tropical Cyclone Precipitation from Station Observations

    Institute of Scientific and Technical Information of China (English)

    REN Fumin; WANG Yongmei; WANG Xiaoling; LI Weijing

    2007-01-01

    In this paper, an objective technique for estimating the tropical cyclone (TC) precipitation from station observations is proposed. Based on a comparison between the Original Objective Method (OOM) and the Expert Subjective Method (ESM), the Objective Synoptic Analysis Technique (OSAT) for partitioning TC precipitation was developed by analyzing the western North Pacific (WNP) TC historical track and the daily precipitation datasets. Being an objective way of the ESM, OSAT overcomes the main problems in OOM,by changing two fixed parameters in OOM, the thresholds for the distance of the absolute TC precipitation (D0) and the TC size (D1), into variable parameters.Case verification for OSAT was also carried out by applying CMORPH (Climate Prediction Center MORPHing technique) daily precipitation measurements, which is NOAA's combined satellite precipitation measurement system. This indicates that OSAT is capable of distinguishing simultaneous TC precipitation rain-belts from those associated with different TCs or with middle-latitude weather systems.

  11. Aerosol-Cloud-Precipitation Interactions in WRF Model:Sensitivity to Autoconversion Parameterization

    Institute of Scientific and Technical Information of China (English)

    解小宁; 刘晓东

    2015-01-01

    Cloud-to-rain autoconversion process is an important player in aerosol loading, cloud morphology, and precipitation variations because it can modulate cloud microphysical characteristics depending on the par-ticipation of aerosols, and aff ects the spatio-temporal distribution and total amount of precipitation. By applying the Kessler, the Khairoutdinov-Kogan (KK), and the Dispersion autoconversion parameterization schemes in a set of sensitivity experiments, the indirect eff ects of aerosols on clouds and precipitation are investigated for a deep convective cloud system in Beijing under various aerosol concentration backgrounds from 50 to 10000 cm−3. Numerical experiments show that aerosol-induced precipitation change is strongly dependent on autoconversion parameterization schemes. For the Kessler scheme, the average cumulative precipitation is enhanced slightly with increasing aerosols, whereas surface precipitation is reduced signifi-cantly with increasing aerosols for the KK scheme. Moreover, precipitation varies non-monotonically for the Dispersion scheme, increasing with aerosols at lower concentrations and decreasing at higher concentrations. These diff erent trends of aerosol-induced precipitation change are mainly ascribed to diff erences in rain wa-ter content under these three autoconversion parameterization schemes. Therefore, this study suggests that accurate parameterization of cloud microphysical processes, particularly the cloud-to-rain autoconversion process, is needed for improving the scientifi c understanding of aerosol-cloud-precipitation interactions.

  12. Asymmetry in ecosystem responses to precipitation: Theory, observation and experimentation

    Science.gov (United States)

    Sala, O.; Gherardi, L.; Reichmann, L.; Peters, D.

    2017-12-01

    Ecosystem processes such as primary production respond to changes in precipitation that occur annually and at longer time scales. The questions guiding this presentation are whether ecosystem responses to wet and dry years are symmetrical. Is the increase in productivity in a wet year similar in absolute value to the decrease in productivity in a dry year following a wet year? Is the response to one dry or wet year similar tot response of several consecutive wet and dry years? Do all plant-functional groups respond in a similar way to changes in precipitation? To address the questions we explore the theory behind a potential asymmetry and report on experimental results. Analysis of the cost and benefits of plant responses to changes in precipitation support the idea asymmetrical responses because the threshold for abscising organs that have already been deployed should be higher than the threshold to deploy new organs. However, experiments in a desert grassland in New Mexico where we experimentally increased and decreased precipitation from one year to the next showed that the response was symmetrical. Another mechanism that may yield asymmetries is the productivity response to changes in precipitation is associated with the shape of the relationship between precipitation and productivity. Straight-line relationship may yield no asymmetries whereas a saturating or concave up relationship may result in different asymmetries. Here, we report results from an experiment that yielded concave down responses for grasses and concave up for shrubs. Finally, we report results from a 10-year experiment showing asymmetric responses of grasses and shrubs. Moreover, the magnitude of the sign of the responses changed with the time since the beginning of the precipitation manipulation.

  13. The effect of scale in daily precipitation hazard assessment

    Directory of Open Access Journals (Sweden)

    J. J. Egozcue

    2006-01-01

    Full Text Available Daily precipitation is recorded as the total amount of water collected by a rain-gauge in 24 h. Events are modelled as a Poisson process and the 24 h precipitation by a Generalised Pareto Distribution (GPD of excesses. Hazard assessment is complete when estimates of the Poisson rate and the distribution parameters, together with a measure of their uncertainty, are obtained. The shape parameter of the GPD determines the support of the variable: Weibull domain of attraction (DA corresponds to finite support variables as should be for natural phenomena. However, Fréchet DA has been reported for daily precipitation, which implies an infinite support and a heavy-tailed distribution. Bayesian techniques are used to estimate the parameters. The approach is illustrated with precipitation data from the Eastern coast of the Iberian Peninsula affected by severe convective precipitation. The estimated GPD is mainly in the Fréchet DA, something incompatible with the common sense assumption of that precipitation is a bounded phenomenon. The bounded character of precipitation is then taken as a priori hypothesis. Consistency of this hypothesis with the data is checked in two cases: using the raw-data (in mm and using log-transformed data. As expected, a Bayesian model checking clearly rejects the model in the raw-data case. However, log-transformed data seem to be consistent with the model. This fact may be due to the adequacy of the log-scale to represent positive measurements for which differences are better relative than absolute.

  14. Precipitation and Deposition of Aluminum-Containing Phases in Tank Wastes

    International Nuclear Information System (INIS)

    Dabbs, Daniel M.; Aksay, Ilhan A.

    2005-01-01

    Aluminum-containing phases compose the bulk of solids precipitating during the processing of radioactive tank wastes. Processes designed to minimize the volume of high-level waste through conversion to glassy phases require transporting waste solutions near-saturated with aluminum-containing species from holding tank to processing center. The uncontrolled precipitation within transfer lines results in clogged pipes and lines and fouled ion exchangers, with the potential to shut down processing operations

  15. High-resolution projections of mean and extreme precipitations over China through PRECIS under RCPs

    Science.gov (United States)

    Zhu, Jinxin; Huang, Gordon; Wang, Xiuquan; Cheng, Guanhui; Wu, Yinghui

    2018-06-01

    The impact of global warming on the characteristics of mean and extreme precipitations over China is investigated by using the Providing REgional Climate Impacts for Studies (PRECIS) model. The PRECIS model was driven by the Hadley Centre Global Environment Model version 2 with Earth System components and coupling (HadGEM2-ES). The results of both models are analyzed in terms of mean precipitation and indices of precipitation extremes (R95p, R99p, SDII, WDF, and CWD) over China at the resolution of 25 km under the Representative Concentration Pathways 4.5 and 8.5 (RCP4.5 and RCP8.5) scenarios for the baseline period (1976-2005) and two future periods (2036-2065 and 2070-2099). With improved resolution, the PRECIS model is able to better represent the fine-scale physical process than HadGEM2-ES. It can provide reliable spatial patterns of precipitation and its related extremes with high correlations to observations. Moreover, there is a notable improvement in temporal patterns simulation through the PRECIS model. The PRECIS model better reproduces the regional annual cycle and frequencies of daily precipitation intensity than its driving GCM. Under RCP4.5 and RCP8.5, both the HadGEM2-ES and the precis project increasing annual precipitation over the entire country for two future periods. Precipitation increase in winter is greater than the increase in summer. The results suggest that increased radiative forcing from RCP4.5 to RCP8.5 would further intensify the magnitude of projected precipitation changes by both PRECIS and HadGEM2-ES. For example, some parts of south China with decreased precipitation under RCP4.5 would expect even less precipitation under RCP8.5; regions (northwest, northcentral and northeast China) with increased precipitation under RCP4.5 would expect more precipitation under RCP8.5. Apart from the projected increase in annual total precipitation, the results also suggest that there will be an increase in the days with precipitation higher than

  16. Bone char quality and defluoridation capacity in contact precipitation

    DEFF Research Database (Denmark)

    Albertus, J.; Bregnhøj, Henrik; Kongpun, M.

    2002-01-01

    are added as in the contact precipitation process. The results show that the columns are able to remove up to 700 bedvolumes, before the concentration of fluoride in the effluent water breaks through, above 1.5 mg/L. Operational removal capacities observed are 7 and 9 mg/L, depending on contact time...... and the dosage of chemicals. It is discussed that longer contact time and higher dosage of calcium and phosphate may result in longer operation periods in the contact precipitation columns....

  17. Mixing and solid suspension in a stirred precipitator

    International Nuclear Information System (INIS)

    Chang, T.P.

    1986-04-01

    Full-scale mixing and solid suspension studies have been conducted to determine the optimum agitator design for precipitators used in plutonium processing. Design considerations include the geometry of precipitator vessels, feed locations, flow patterns, and product requirements. Evaluations of various agitator designs are based on their capabilities: (1) to achieve uniform mixing of reactants in minimum time, (2) to suspend slurry uniformly throughout the vessel, and (3) to minimize power consumption without inducing air entrainment. Tests of full-scale agitator designs showed that significant improvements in mixing, solid suspension, and energy consumption were achieved

  18. Precipitation of yellowcake from pregnant regenerate by various reagents

    International Nuclear Information System (INIS)

    Rychkov, V.N.; Smirnov, A.L.; Skripchenko, S.Yu.; Pastukhov, A.M.

    2017-01-01

    The application of an ammonia solution, sodium hydroxide solution and ammonium carbonate/bicarbonate solution as agents for the uranium precipitation from industrial pregnant regenerate was investigated. The effect various process parameters on the composition and properties of obtained uranium compounds was studied. According to the results, only the yellowcake obtained by precipitation using ammonium carbonate/bicarbonate solution is a high-purity product and meets the specification requirements. The uranium content in this concentrate is 69-72%. The particle mean diameter is 12-16 µm. The use of other neutralizing agents leads to decrease purity of the final product. (author)

  19. Effect of indifferent anions on reactions of cadmium ferrocyanide precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Gyunner, Eh A; Mel' nichenko, L M; Vel' mozhnyj, I S [Simferopol' skij Gosudarstvennyj Univ. (Ukrainian SSR)

    1982-08-01

    To clarify the effect of indifferent anions on the processes of cadmium ferrocyanide precipitation the interaction in six systems of the type CdXsub(m)-Msub(4)R-Hsub(2)O (X-Cl/sup -/, CH/sub 3/COO/sup -/, SO/sub 4//sup 2 -/; M-K/sup +/, NH/sub 4//sup +/; R-(Fe(CN)/sub 6/)/sup 4 -/) is studied using the methods of physicochemical analysis (the method of residual concentrations, refractometry). Composition and formation regions of low-soluble interaction products are determined. Effect of anion X nature on interaction character is stated in the series Cl/sup -/, CH/sub 3/COO/sup -/, SO/sub 4//sup 2 -/ in mixtures with incomplete Cd/sup 2 +/ precipitation a tendency for the increase of Cd/sup 2 +/:R/sup 4 -/ ratios in precipitates formed is observed.

  20. The adsorption of orthophosphate onto casein-iron precipitates.

    Science.gov (United States)

    Mittal, Vikas A; Ellis, Ashling; Ye, Aiqian; Edwards, Patrick J B; Singh, Harjinder

    2018-01-15

    This study explored the interactions of orthophosphate with casein-iron precipitates. Casein-iron precipitates were formed by adding ferric chloride at ≥10mM to sodium caseinate solutions ranging in concentration from 1 to 3%(w/v). The addition of different concentrations of orthophosphate solution to the casein-iron precipitates resulted in gradual adsorption of the orthophosphate, causing re-dispersion of the casein-iron complexes. The interactions of added orthophosphate with iron in the presence and absence of caseins are postulated, and new mechanisms are proposed. The re-dispersed soluble complexes of casein-iron-orthophosphate generated using this process could be used as novel iron fortificants. Copyright © 2017 Elsevier Ltd. All rights reserved.