scholarly journals The photolysis module JVAL-13.99gmdd, compatible with the MESSy standard, and the JVal PreProcessor (JVPP)

2014 ◽  
Vol 7 (2) ◽  
pp. 2501-2523 ◽  
Author(s):  
R. Sander ◽  
P. Jöckel ◽  
O. Kirner ◽  
A. T. Kunert ◽  
J. Landgraf ◽  
...  
Keyword(s):  
Cross Sections ◽  
Rate Coefficients ◽  
Quantum Yields ◽  
Atmospheric Conditions ◽  
Atmospheric Molecules ◽  
Community Model ◽  
Polynomial Curve ◽  
Polynomial Curve Fitting ◽  
Auxiliary Program ◽  
General Public License

Abstract. We present version 13.99gmdd of the photolysis module JVAL. Taking atmospheric conditions as input, JVAL calculates photolysis rate coefficients, i. e., the speed of dissociation of atmospheric molecules in the sunlight. Computational efficiency is obtained through the use of parameters for polynomial curve fitting and lookup tables. JVAL also includes the auxiliary program JVPP (JVal PreProcessor) which pre-calculates these parameters based on the absorption cross sections and quantum yields of the atmospheric molecules. It is possible to either use JVAL as a stand-alone program, or as a module inside the Modular Earth Submodel System (MESSy). JVAL is a community model published under the GNU General Public License.

scholarly journals The photolysis module JVAL-14, compatible with the MESSy standard, and the JVal PreProcessor (JVPP)

2014 ◽  
Vol 7 (6) ◽  
pp. 2653-2662 ◽  
Author(s):  
R. Sander ◽  
P. Jöckel ◽  
O. Kirner ◽  
A. T. Kunert ◽  
J. Landgraf ◽  
...  
Keyword(s):  
Cross Sections ◽  
Rate Coefficients ◽  
Quantum Yields ◽  
Atmospheric Conditions ◽  
Lyman Alpha ◽  
Atmospheric Molecules ◽  
Community Model ◽  
Polynomial Curve ◽  
Polynomial Curve Fitting ◽  
Physical Changes

Abstract. We present version 14 of the photolysis module JVAL. Taking atmospheric conditions as input, JVAL calculates photolysis rate coefficients, i.e. the speed of dissociation of atmospheric molecules in the sunlight. Computational efficiency is obtained through the use of parameters for polynomial curve fitting and lookup tables. Physical changes compared to the previous version include a parameterization of the Lyman-alpha absorption, and an update of the UV/VIS cross sections to the most recent recommended values. JVAL also includes the auxiliary program JVPP (JVal PreProcessor) which pre-calculates these parameters based on the absorption cross sections and quantum yields of the atmospheric molecules. It is possible to use JVAL either as a stand-alone program or as a module inside the Modular Earth Submodel System (MESSy). JVAL is a community model published under the GNU General Public License.

Mechanisms of Ozone Reactions in the Troposphere

2015 ◽  
Author(s):  
Jack G. Calvert ◽  
John J. Orlando ◽  
William R. Stockwell ◽  
Timothy J. Wallington
Keyword(s):  
Cross Sections ◽  
Tropospheric Ozone ◽  
Stratospheric Ozone ◽  
Excited Electronic State ◽  
Rate Coefficients ◽  
Quantum Yields ◽  
Atmospheric Conditions ◽  
Trace Impurities ◽  
Reactive Trace Gases ◽  
Ozone Photochemistry

In Chapter I, we identified the origin of stratospheric ozone and its role in limiting the short wavelengths of sunlight reaching the Earth. We also saw the importance of trace impurities of NOx and hydrocarbons in the development of tropospheric ozone. In this chapter, we review and evaluate the chemical reactions of ozone that create the important hydroxyl (HO) radical. It is the photodecomposition of tropospheric ozone that is the major source of the important HO radical, and it is the HO radical that initiates the destruction of most of the reactive trace gases that are emitted into the atmosphere. Ozone also serves as a major reactant for removal of the alkenes and other reactive unsaturated compounds, and, in this chapter, we review and evaluate the rate coefficients and mechanisms of these reactions and the expected products that result from them. The reactions that generate oxygen atoms in their first excited electronic state, O(1D) atoms, and ultimately HO radicals within the atmosphere are initiated through ozone photodecomposition: . . . O3 (X1A1) + hν → O(1D) + O2(a1Δg) (I) . . . . . . → O(1D) + O2(X3Σ–g) (II) . . . A fraction of the O(1D) atoms formed in the reactions (I) and (II) react with water molecules to generate HO radicals in reaction (1) and a larger fraction are deactivated by collisions with N2 and O2 molecules to form ground state O(3P) atoms in reaction (2): . . . O(1D) + H2O → HO + HO (1) . . . . . . O(1D) + M (N2, O2) → O(3P) + M (N2, O2) (2) . . . The competition between H2O and other air molecules (N2, O2) for reaction with O(1D) atoms results in HO generation being dependent on relative humidity. Rate coefficients for reaction of O(1D) with H2O, N2, and O2 at 298 K (in units of 10−10 cm3 molecule−1 s−1) recommended by the International Union of Pure and Applied Chemistry (IUPAC) panel are 2.14, 0.31, and 0.40, respectively (Atkinson et al., 2004). To better understand the factors that control HO formation, we will review ozone photochemistry, its cross sections, quantum yields of its major photodecomposition modes, and its photolysis frequencies under varied atmospheric conditions.

scholarly journals The atmospheric chemistry box model CAABA/MECCA-3.0

2011 ◽  
Vol 4 (2) ◽  
pp. 373-380 ◽  
Author(s):  
R. Sander ◽  
A. Baumgaertner ◽  
S. Gromov ◽  
H. Harder ◽  
P. Jöckel ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Steady State ◽  
Monte Carlo Simulations ◽  
Atmospheric Chemistry ◽  
General Public ◽  
Box Model ◽  
Rate Coefficients ◽  
Community Model ◽  
User Friendly ◽  
General Public License

Abstract. We present version 3.0 of the atmospheric chemistry box model CAABA/MECCA. In addition to a complete update of the rate coefficients to the most recent recommendations, a number of new features have been added: chemistry in multiple aerosol size bins; automatic multiple simulations reaching steady-state conditions; Monte-Carlo simulations with randomly varied rate coefficients within their experimental uncertainties; calculations along Lagrangian trajectories; mercury chemistry; more detailed isoprene chemistry; tagging of isotopically labeled species. Further changes have been implemented to make the code more user-friendly and to facilitate the analysis of the model results. Like earlier versions, CAABA/MECCA-3.0 is a community model published under the GNU General Public License.

scholarly journals The atmospheric chemistry box model CAABA/MECCA-3.0gmdd

2011 ◽  
Vol 4 (1) ◽  
pp. 197-217 ◽  
Author(s):  
R. Sander ◽  
A. Baumgaertner ◽  
S. Gromov ◽  
H. Harder ◽  
P. Jöckel ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Steady State ◽  
Monte Carlo Simulations ◽  
Atmospheric Chemistry ◽  
General Public ◽  
Box Model ◽  
Rate Coefficients ◽  
Community Model ◽  
User Friendly ◽  
General Public License

Abstract. We present version 3.0gmdd of the atmospheric chemistry box model CAABA/MECCA. In addition to a complete update of the rate coefficients to the most recent recommendations, a number of new features have been added: chemistry in multiple aerosol size bins; automatic multiple simulations reaching steady-state conditions; Monte-Carlo simulations with randomly varied rate coefficients within their experimental uncertainties; calculations along Lagrangian trajectories; mercury chemistry; more detailed isoprene chemistry; tagging of isotopically labeled species. Further changes have been implemented to make the code more user-friendly and to facilitate the analysis of the model results. Like earlier versions, CAABA/MECCA-3.0gmdd is a community model published under the GNU General Public License (GPL).

Rotational de-excitations of C3H+ (1Σ+) by collision with He: new ab initio potential energy surface and scattering calculations

2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Energy Surface ◽  
Molecular Ions ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Collisional Rate Coefficients

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

Analysis of Crimping of Large Diameter Welding Pipe

2014 ◽  
Vol 997 ◽  
pp. 517-521
Author(s):  
Li Feng Fan ◽  
Ying Gao ◽  
Jian Bin Yun ◽  
Lin Feng Dong
Keyword(s):  
Analytical Model ◽  
Large Diameter ◽  
Forming Process ◽  
Technical Parameters ◽  
Polynomial Curve ◽  
Welding Pipe ◽  
X80 Steel ◽  
Polynomial Curve Fitting ◽  
Effective Path ◽  
Submerged Arc

Crimping is widely used in production of large diameter submerged-arc welding pipes. Traditionally, the designers obtain the technical parameters for crimping from experience or trial-errors by experiments. To tackle this problem, a theoretical analytical model is proposed to analysis crimping forming process. In this paper, taking the crimping of X80 steel Φ1219mm×22mm×12000mm welding pipe for instance, the theoretical analytical model is constructed by quadratic polynomial curve fitting technique and mechanics theory. And it is verified by a comparison with experiment results. Thus, the presented model of this research provides an effective path to design crimping parameters.

EIGEN-TEMPERATURE MODEL FOR THE ANNUAL AIR TEMPERATURE MOVEMENT EVALUATION AND FORECAST

2013 ◽  
Vol 04 (03) ◽  
pp. 1350008 ◽  
Author(s):  
ZONG-CHANG YANG
Keyword(s):  
Air Temperature ◽  
Principal Component ◽  
Ar Model ◽  
Temperature Model ◽  
Polynomial Curve ◽  
Actual Observation ◽  
Fitting Algorithm ◽  
Global Concern ◽  
Polynomial Curve Fitting ◽  
Result Analysis

Climate variability and its changes are issues of broader global concern. This study addresses the annual air temperature movement evaluation and forecasting based on principal component analysis (PCA). An Eigen-temperature model for describing the annual air temperature movement by employing PCA is introduced. Subspace for evaluation is generated by selecting principal orthogonal eigenvectors of covariance matrix of temperature data. The principal eigenvectors are called "Eigen-temperatures", since they are eigenvectors and each temperature movement is described by them. Each temperature movement is projected onto the subspace of eigenspace, and described by a linear combination of the Eigen-temperatures. Then, a forecast method for the temperature movement by employing the Eigen-temperatures is proposed. Forecast is implemented with polynomial curve fitting algorithm to estimate subsequent representation weights for the subsequent temperature movement with respect to the "Eigen-temperatures" generated by its previous temperature movements. The proposed Eigen-temperature model is applied to evaluation and forecasting for annual temperature movement at Tongchuan observation station of China from 1962 to 1971 and from 1994 to 2002. Experimental results agreeing well with actual observation values show workability of the proposed. Result analysis indicates its effectiveness that the proposed Eigen-temperature model is outperforming the classical AR model and the BP-ANN on the forecast tasks.

Inelastic scattering of interstellar silyl cyanide (SiH3CN) by helium atoms : cross-sections and rate coefficients for A- and E-SiH3CN

2021 ◽  
Vol 507 (4) ◽  
pp. 5264-5271
Author(s):  
Manel Naouai ◽  
Abdelhak Jrad ◽  
Ayda Badri ◽  
Faouzi Najar
Keyword(s):  
Inelastic Scattering ◽  
Total Energy ◽  
Cross Sections ◽  
Three Dimensional ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Explicitly Correlated ◽  
Correlation Consistent ◽  
Triple Excitation

ABSTRACT Rotational inelastic scattering of silyl cyanide (SiH3CN) molecule with helium (He) atoms is investigated. Three-dimensional potential energy surface (3D-PES) for the SiH3CN–He interacting system is carried out. The ab initio 3D-PES is computed using explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation CCSD(T)-F12a connected to augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. A global minimum at (R = 6.35 bohr; θ = 90○; ϕ = 60○) with a well depth of 52.99 cm−1 is pointed out. Inelastic rotational cross-sections are emphasized for the 22 first rotational levels for total energy up to 500 cm−1 via close coupling (CC) approach in the case of A-SiH3CN and for the 24 first rotational levels for total energy up to 100 cm−1 via CC and from 100 to 500 cm−1 via coupled states (CS) in the case of E-SiH3CN. Rate coefficients are derived for temperature until 80 K for both A- and E-SiH3CN–He systems. Propensity rules are obtained for |ΔJ| = 2 processes with broken parity for A-SiH3CN and for |ΔJ| = 2 processes with |ΔK| = 0 and unbroken parity for E-SiH3CN.

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