Intercomparison of retrieval codes used for the analysis of high-resolution, ground-based FTIR measurements

A rigorous and systematic intercomparison of codes used for the retrieval of trace gas profiles from high-resolution ground-based solar absorption FTIR measurements is presented for the first time. Spectra were analyzed with the two widely used independent, retrieval codes: SFIT2 and PROFFIT9. Vertical profiles of O₃, HNO₃, HDO, and N₂O were derived from the same set of typical observed spectra. Analysis of O₃ was improved by using updated line parameters. It is shown that profiles and total column amounts are in excellent agreement, when similar constraints are applied, and that the resolution kernel matrices are also consistent. Owing to the limited altitude resolution of ground-based observations, the impact of the constraints on the solution is not negligible. It is shown that the results are also compatible for independently chosen constraints. Perspectives for refined constraints are discussed. It can be concluded that the error budget introduced by the radiative transfer code and the retrieval algorithm on total columns deduced from high-resolution ground-based solar FTIR spectra is below 1%.     

An implicit characteristic-flux-averaging method for the euler equations for real gases

A formulation of an implicit characteristic-flux-averaging method for the unsteady Euler equations with real gas effects is presented. Incorporation of a real gas into a general equation of state is achieved by considering the pressure as a function of density and specific internal energy. The Ricmann solver as well as the flux-split algorithm are modified by introducing the pressure derivatives with respect to density and internal energy. Expressions for calculating the values of the flow variables for a real gas at the cell faces are derived. The Jacobian matrices and the eigenvectors are defined for a general equation of state. The solution of the system of equations is obtained by using a mesh-sequencing method for acceleration of the convergence. Finally, a test case for a simple form of equation of state displays the differences from the corresponding solution for an ideal gas.     

An efficient hydrodynamic cellular automata for simulating fluids with large viscosities

A hydrodynamic cellular automata (HDCA) for simulating two-dimensional fluids with large viscosities is proposed. The model is characterized by a mean free path which is of the same size as in the FHP-II model, but with a viscosity more than 10 times larger. This new model should make simulations of flows at low Reynolds number more efficient.     

The variation of carrier gas viscosities with temperature

After describing simplified equations exspressing the temparature dependency of the viscosity of carrier gases (helium, nitrogen and hydrogen ) relative to a base value, absolute relationships based on the kinetic theory of gases are discussed. Comparative data obtained using various calculation methods are given and are compared to measured values. Based on the kinetic relationshipsm, of viscosity. Finally, the influence of pressure on the viscosity is also briefly discussed. As a supplement, Viscosity data are tabulated for the three gases in the range of 0°C to 400°C in increments of 2 K, calculated using the kinetic relationships.     

From gas dynamics to pressureless gas dynamics

This paper is devoted to the convergence of solutions of the compressible Euler equations towards solutions of the pressureless gas dynamics system, when the pressure tends to 0. The goal is to prove accurate uniform bounds for particular solutions of the Euler equations.

     

Thermal decomposition of Cd(CH3COO)2·2H2O studied by a coupled TG-DTA-MS method

The thermal decomposition of cadmium acetate dihydrate in helium and in air atmosphere has been investigated by means of a coupled TG-DTA-MS method combined with X-ray diffraction analysis. Dehydration of Cd(CH₃COO)₂·2H₂O is a two-stage process with Cd(CH₃COO)₂·H₂O as intermediate. The way of Cd(CH₃COO)₂ decomposition strongly depends on the surrounding gas atmosphere and the rate of heating. CdO, acetone and CO₂ are the primary products of decomposition in air. In helium decomposition goes by two parallel and consecutive reactions in which intermediates, Cd and CdCO₃, are formed. Metallic cadmium oxidizes and cadmium carbonate decomposes giving CdO. Some of the metallic cadmium, depending on the heating rate and the concentration of oxygen, evaporates. Acetone is partially oxidized in secondary reactions with oxygen. This revised version was published online in July 2006 with corrections to the Cover Date.     

IR multiphoton dissociation of CF3I. Pressure effect with inert and reactive gases

The IR multiphoton dissociation of CF₃I has been studied in the presence of isobutane and with isobutane and Ar and CO₂ as inert gases. The dependence of the reaction probability P(Φ) with fluence (ϕ) is confirmed. Modeling of the experimental results shows that for the energy transfer processes the average energy transferred per collision 〈†E〉_d varies with (ϕ).     

Solubility of gases in liquids. 18. High-precision determination of Henry fugacities for argon in liquid water at 2 to 40°C

The solubility of argon in pure liquid water was measured at ca. 100 kPa and from 2 to 40°C using an analytical method characterized by an imprecision of about ±0.05%. From the experimental results, Henry fugacities H _2,1 (T,P _s,1 ) (also known as Henry's Law constants or Henry coefficients) at the vapor pressure P _s,1 of water as well as Ostwald coefficients L _2,1 at infinite dilution were obtained. Measurements were made at roughly 0.5°C and/or 1° intervals between 2 and 8°C (region I), and at 5°C intervals above 10°C (region II). A difference plot lnH _2,1 /T suggests an unusual temperature dependence in region I, i.e., between 2 and 8°C. Because of this, the data were treated separately in two parts corresponding to these two regions. Our results are compared with the recent high-precision data of Krause and Benson (Henry fugacities), and with calorimetrically determined quantities (enthalpies and heat capacities of solution). Finally, experimental results are compared with values calculated via scaled particle theory.Communicated in part at the 2^nd International Symposium on Solubility Phenomena in Newark, New Jersey, August 12–15, 1986, and at the 4^th ISSP in Troy, New York, July 20–August 3, 1990.     

FFC-1离子交换纤维对酸碱有害气体吸附性能的研究

系统考察了不同直径及反离子形式的FFC-1聚羧酸离子交换纤维对酸碱有害气体的穿透吸附,各种温、湿度条件下的吸水率,以及作为有害气体吸附滤除材料的重复使用与再生性能。研究表明:FFC-1纤维直径的减小有利于提高对有害气体的动态吸附容量。在体系温度、相对湿度分别为15℃、50%时,以3D腈纶为起始原料的钠型FFC-1离子交换纤维的吸水率≥350mg/g.纤维;对SO2的穿透吸附容量可达200mg/g.纤维。FFC-1离子交换纤维具有良好的重复使用与再生能力,经20次再生循环使用后,纤维交换容量未见明显变化。