Validation of the SKBU1 Uranium Thermodynamic Data Base for its use in Geochemical Calculations with EQ3/6

1988 ◽  
Vol 127 ◽  
Author(s):  
Jordi Bruno ◽  
Ignasi Puigdomenech
Keyword(s):  
Data Base ◽  
Thermodynamic Data ◽  
Carbonate Concentration ◽  
Wide Range

ABSTRACTA validation of the SKBUl uranium thermodynamic data base is performed. Experimental solubilities for schoepite, rutherfordite, UO2(am) and UO2(c) determined in a wide range of pH, PCO2, carbonate concentration and temperature are compared to calculated ones by using EQ3NR.

Monte Carlo simulation of chlorine adsorbed on graphite

1988 ◽  
Vol 66 (4) ◽  
pp. 955-962 ◽  
Author(s):  
Soong-Hyuck Suh ◽  
Seamus F. O'Shea
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Basal Plane ◽  
Thermodynamic Data ◽  
Molecular Chlorine ◽  
Monte Carlo Calculations ◽  
Structure And Dynamics ◽  
Wide Range ◽  
Do So ◽  
Molecule Surface

Monte Carlo calculations are reported for patches of molecular chlorine adsorbed on the basal plane of graphite. A variety of combinations of intermolecular and molecule–surface potentials have been tested, and the resulting structural predictions cover a wide range of behaviour. None of the combinations employed here can explain the recent experimental observations, but it is clear that at least some could be adjusted to do so. However, the lack of thermodynamic data concerning the interaction between the molecules and the surface presents a major obstacle. Further experiments which give information about the energetics of the system are needed before a definitive account of the structure and dynamics can be given.

Human Factors Design Criteria for Transilluminated Displays

1977 ◽  
Vol 21 (1) ◽  
pp. 78-82
Author(s):  
Robert J. Hall ◽  
James C. Sanderlin
Keyword(s):  
Human Factors ◽  
Data Base ◽  
Physical Simulation ◽  
State Of The Art ◽  
Design Criteria ◽  
Human Engineering ◽  
Modeling Tools ◽  
Data Base Design ◽  
Wide Range ◽  
Base Design

This paper reviews recent studies of human factors design criteria for transilluminated displays and the development of a computerized data base and modeling tools to supplement human engineering design criteria for visual displays. The inherent limitations of present military standards for dealing with a wide range of variables in a variety of operational environments and the need to include changes in the state-of-the-art are addressed. Data base design and computer modeling are suggested as an intermediate approach between out of date standards and costly physical simulation.

The Solubility of Actinides in the Near-Field

1985 ◽  
Vol 50 ◽  
Author(s):  
F. T. Ewart ◽  
R. M. Howse ◽  
H. P. Thomason ◽  
S. J. Williams ◽  
J. E. Cross
Keyword(s):  
Data Base ◽  
Thermodynamic Data ◽  
Near Field ◽  
Geochemical Modelling ◽  
Actinide Elements

AbstractThe solubility of some of the radiologically important actinide elements have been determined in a water whose chemistry was representative of that believed to exist in potential repositories in the U.K. The solubilities of the actinides have been determined as a function of the pH of the water. The results of these experiments have been compared with the results of predictions made using the PHREEQE geochemical modelling code in order to test and validate the data base used in the model. In the light of these comparisons, suggestions are made for alternative values for the thermodynamic data and for further studies.

Improved identification of evaporation rates and thermodynamic data by Monte-Carlo method

2020 ◽  
Author(s):  
Anna Shcherbacheva ◽  
Tapio Helin ◽  
Heikki Haario ◽  
Hanna Vehkamäki
Keyword(s):  
Monte Carlo ◽  
Sulfuric Acid ◽  
Thermodynamic Data ◽  
Particle Formation ◽  
Forward Problem ◽  
Dependent Data ◽  
New Particle Formation ◽  
Free Energies ◽  
Wide Range ◽  
Cluster Composition

<p>Atmospheric new particle formation and successive cluster growth to aerosol particles is an important field of research, in particular due to climate change phenomena and air quality monitoring. Recent developments in the instrumentation have enabled quantification of ionic clusters formed in the gas phase at the first steps of particle formation under atmospherically relevant mixing ratios. However, electrically neutral clusters are prevalent in atmospheric conditions, and thus must be charged prior to detection by mass spectrometer. The charging process can lead to cluster fragmentation and thus alter the measured cluster composition.</p><p>Even when the cluster composition can be measured directly, this does not quantify individual cluster-level properties, such as cluster collision and evaporation rates. Collision rates contain relatively small uncertainties in comparison to evaporation rates, which are computed using detailed balance assumption together with the free energies of cluster formation, which can in turn be obtained from Quantum chemistry (QC) methods. As evaporation rates depend exponentially on the free energies, even difference by several kcal/mol between different QC methods results in orders of magnitude differences in evaporation rates.</p><p>On the other hand, in spite of the error margins associated with the evaporation rates, simulations of cluster populations, which incorporate collision and evaporation rates as free parameters (such as Becker-Döring models), have demonstrated good qualitative agreement with experimental data. The Becker-Döring equations are a system of Ordinary Differential equations (ODE) which account for cluster birth and death processes, as well as external sinks and sources. In mathematical terms, prediction of cluster concentrations using kinetic simulations with given cluster collision and evaporation rates is called a forward problem.</p><p>In the present study, we focus on the so-called inverse problem of how to derive the evaporation rates and thermodynamic data (enthalpy change and entropy change due to addition or removal of molecule) from available measurements, rather than on the forward problem. We do this by Delayed Rejection Adaptive Monte Carlo (DRAM) method for the system containing sulfuric acid and ammonia with the maximal size of the pentamer. Initially, we tested the method on the synthetic data created from Atmospheric Cluster Dynamic Code (ACDC) simulations. By so doing, we identify the combination of fitted parameters and concentration measurements, which leads to the best identification of the evaporation rates. Additionally, we demonstrated that the temperature-dependent data yield better estimates of the evaporation rates as compared to the time-dependent data measured before the system has reached the steady state.</p><p>Next, we apply the technique to improve the identification of the evaporation rates from CLOUD chamber data, which contain cluster concentrations and new particle formation rates measured at different temperatures and a wide range of atmospherically relevant sulfuric acid and ammonia concentrations. As a result, we were able to obtain the probability density functions (PDFs) that show small standard variations for thermodynamic data. By using the values from the PDFs as parameters in the ACDC model, we achieve a fair agreement with the measured NPFs and cluster concentrations for a wide range of temperatures.</p>

scholarly journals Data of hydraulic properties of North East and Central German soils

2010 ◽  
Vol 3 (1) ◽  
pp. 131-142 ◽  
Author(s):  
U. Schindler ◽  
L. Müller
Keyword(s):  
Bulk Density ◽  
Data Base ◽  
Mineral Soil ◽  
Organic Matter Content ◽  
Water Retention Curve ◽  
Organic Soils ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
North East ◽  
Wide Range

Abstract. The paper presents a data base of soil hydrological properties of North East and Central German soils. Included are measured data of the soil water retention curve and the unsaturated hydraulic conductivity function. Information to geo reference, soil type and horizon are given. Additional soil physical data like particle size distribution, dry bulk density, organic matter content and other variables are presented and its measurement is methodically described. The data base includes original measurement results of 278 organic and of 497 mineral soil samples from 103 sites. The mineral soils cover a wide range of texture classes and dry bulk densities. The organic soils and samples vary in dependence on the degree of decomposition and mineralization, the dry bulk density and the total porosity.

scholarly journals The Chemkin Thermodynamic Data Base

1990 ◽  
Author(s):  
R. Kee ◽  
F. Rupley ◽  
J. Miller
Keyword(s):  
Data Base ◽  
Thermodynamic Data

scholarly journals New particle formation from sulfuric acid and ammonia: nucleation and growth model based on thermodynamics derived from CLOUD measurements for a wide range of conditions

2019 ◽  
Author(s):  
Andreas Kürten
Keyword(s):  
Sulfuric Acid ◽  
Growth Model ◽  
Thermodynamic Data ◽  
Particle Formation ◽  
Nucleation And Growth ◽  
Aerosol Size Distribution ◽  
Formation Mechanisms ◽  
Strong Impact ◽  
New Particle Formation ◽  
Wide Range

Abstract. Understanding new particle formation and growth is important because of the strong impact of these processes on climate and air quality. Measurements to elucidate the main new particle formation mechanisms are essential; however, these mechanisms have to be implemented in models to estimate their impact on the regional and global scale. Parameterizations are computationally cheap ways of implementing nucleation schemes in models but they have their limitations, as they do not necessarily include all relevant parameters. Process models using sophisticated nucleation schemes can be useful for the generation of look-up tables in large-scale models or for the analysis of individual new particle formation events. In addition, some other important properties can be derived from a process model that implicitly calculates the evolution of the full aerosol size distribution, e.g., the particle growth rates. Within this study, a model (SANTIAGO, Sulfuric acid Ammonia NucleaTIon And GrOwth model) is constructed that simulates new particle formation starting from the monomer of sulfuric acid up to a particle size of several hundred nanometers. The smallest sulfuric acid clusters containing one to four acid molecules and varying amount of base (ammonia) are allowed to evaporate in the model, whereas growth beyond the pentamer (5 sulfuric acid molecules) is assumed to be entirely collision-controlled. The main goal of the present study is to derive appropriate thermodynamic data needed to calculate the cluster evaporation rates as a function of temperature. These data are derived numerically from CLOUD (Cosmics Leaving OUtdoor Droplets) chamber new particle formation rates for neutral sulfuric acid-water-ammonia nucleation at temperatures between 208 K and 292 K. The numeric methods include an optimization scheme to derive the best estimates for the thermodynamic data (dH and dS) and a Monte Carlo method to derive their probability density functions. The derived data are compared to literature values. Using different data sets for dH and dS in SANTIAGO detailed comparison between model results and measured CLOUD new particle formation rates is discussed.

scholarly journals New particle formation from sulfuric acid and ammonia: nucleation and growth model based on thermodynamics derived from CLOUD measurements for a wide range of conditions

2019 ◽  
Vol 19 (7) ◽  
pp. 5033-5050 ◽  
Author(s):  
Andreas Kürten
Keyword(s):  
Sulfuric Acid ◽  
Growth Model ◽  
Thermodynamic Data ◽  
Particle Formation ◽  
Nucleation And Growth ◽  
Aerosol Size Distribution ◽  
Formation Mechanisms ◽  
Strong Impact ◽  
New Particle Formation ◽  
Wide Range

Abstract. Understanding new particle formation and growth is important because of the strong impact of these processes on climate and air quality. Measurements to elucidate the main new particle formation mechanisms are essential; however, these mechanisms have to be implemented in models to estimate their impact on the regional and global scale. Parameterizations are computationally cheap ways of implementing nucleation schemes in models, but they have their limitations, as they do not necessarily include all relevant parameters. Process models using sophisticated nucleation schemes can be useful for the generation of look-up tables in large-scale models or for the analysis of individual new particle formation events. In addition, some other important properties can be derived from a process model that implicitly calculates the evolution of the full aerosol size distribution, e.g., the particle growth rates. Within this study, a model (SANTIAGO – Sulfuric acid Ammonia NucleaTIon And GrOwth model) is constructed that simulates new particle formation starting from the monomer of sulfuric acid up to a particle size of several hundred nanometers. The smallest sulfuric acid clusters containing one to four acid molecules and a varying amount of base (ammonia) are allowed to evaporate in the model, whereas growth beyond the pentamer (five sulfuric acid molecules) is assumed to be entirely collision-controlled. The main goal of the present study is to derive appropriate thermodynamic data needed to calculate the cluster evaporation rates as a function of temperature. These data are derived numerically from CLOUD (Cosmics Leaving OUtdoor Droplets) chamber new particle formation rates for neutral sulfuric acid–water–ammonia nucleation at temperatures between 208 and 292 K. The numeric methods include an optimization scheme to derive the best estimates for the thermodynamic data (dH and dS) and a Monte Carlo method to derive their probability density functions. The derived data are compared to literature values. Using different data sets for dH and dS in SANTIAGO detailed comparison between model results and measured CLOUD new particle formation rates is discussed.

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