An experimental and numerical investigation of the catalytic-rich/gaseous-lean combustion of H2/CO/air mixtures at 8 bar

The catalytic-rich/gaseous-lean (R/L) combustion concept was investigated experimentally and numerically for syngas fuels with H₂:CO volumetric ratios 1:0, 4:1 and 1:2, catalytic-rich stoichiometries φ_rich = 2–10 (including operation without air), pressure of 8 bar and air preheat of 673 K. Experiments were performed in a subscale R/L burner with optical access to both catalytic-rich and gaseous-lean stages. OH-PLIF monitored the turbulent combustion in the gaseous-lean stage, OH*-chemiluminescence assessed the propensity for homogeneous ignition in the catalytic-rich stage, and exhaust gas analysis provided the NOx and CO emissions. Two-dimensional simulations were carried out for both stages, while a 1-D opposed-jet code modeled the NOx emissions. The exothermicity of the heterogeneous reactions promoted homogeneous ignition and flame anchoring in the upstream parts of the catalytic-rich stage and allowed for complete consumption of the deficient O₂ reactant, a process that could not be achieved by the catalytic pathway alone due to transport limitations. Homogeneous combustion in the catalytic-rich stage was beneficial for attaining the highest possible fuel pre-conversion. The catalyst not only initiated gaseous combustion but also mitigated potential NOx emissions from the catalytic-rich stage at the highest pre-conversions (lowest φ_rich) and highest CO-content mixtures. Two-sided diffusion flames were established in the gaseous-lean stage due to the recirculation of O₂-rich combustion products, which was advantageous for the burner compactness. It was shown that cardinal to the R/L concept was the fact that a decreasing φ_rich led to an increased heat transfer from the catalytic-rich stage to the bypass air, which reduced the enthalpy in the fuel stream of the gaseous-lean stage and thus lowered the peak flame temperatures (by 400 K for H₂:CO = 1:0). The reduction in flame temperatures with decreasing φ_rich led to a six-fold drop in NOx emissions, while CO emissions were less than 5 ppmv.     

Temperature and density dependence of μ-catalysis cycling rate in dense D/T and H/D/T gas mixtures

Muon catalyzed dt fusion in dense D/T and H/D/T gas mixtures of hydrogen isotopes is studied by the MCF collaboration at JINR. The measurements were carried out with a high pressure target at the JINR phasotron in the temperature range 300-800 K at mixture densities . Tentative experimental results obtained by several analysis methods are presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Inversion doubling in the ν2 vibration-rotation band of NH2D and ND2H

This paper is concerned with an analysis of both ¹⁴NH₂D and ¹⁴ND₂H spectra obtained in the 730- to 1080-cm⁻¹ region with a long-path Fourier transform spectrometer. The assignment of the observed transitions together with a theoretical analysis of the vibration-inversion-rotation energy levels concerned with these transitions allows the first determination of the spectroscopic constants related to the symmetric and antisymmetric upper levels of the fundamental ν₂ band.     

A study of the ground states of CaC2H2+,CaC2D2+ and CaC2H4+

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A new analysis of the ν2 fundamental band of H2O^＋＊

This paper reports that the absorption spectra of H2O^＋ have been measured by tunable mid-infrared diode laser spectroscopy in the spectral range of 1100-1380 cm^-1. The H2O＋ ions are generated in an AC glow discharge of the gaseous mixtures of H2O/He and detected with the velocity modulation technique. Forty new lines are assigned to the ν2 fundamental band of H2O^＋ （X^2B1）. The observed lines together with other data published previously are fitted to the standard effective Hamiltonian of an asymmetric top, yielding a set of improved rotational constants, spin-rotation constants and their quartic and sextic centrifugal distortion constants for the ν2=1 vibrational state of H2O＋.     

Measurement of the vector A y and tensor A yy , A xx , A xz analyzing powers for the dd → 3H p reaction at 200 MeV

The data on the vector A _y and tensor A _yy , A _xx , A _xz analyzing powers for the d → ³H p reaction have been obtained at the energy of the initial deuteron of 200MeV in the angular range of 0–95 degrees in the c.m.s. The calculations performed within one-nucleon exchange model with the use of the standard three-nucleon bound state wave functions fail to reproduce the data on the tensor analyzing powers.     

A new approach for realizing the optical morphological dilation of 1－D gray images

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Fundamental and combination bands of CO2–C2H2 and CO2–C2D2 in the mid-infrared region

Spectra of the weakly bound CO₂–C₂H₂ and CO₂–C₂D₂ complexes are observed in the regions of CO₂ ν₃ (≈ 2349 cm^?1) and C₂D₂ ν₃ (≈ 2440 cm^?1) fundamental vibrations, using an infrared optical parametric oscillator to probe a pulsed supersonic slit-jet expansion. Five bands are measured and analysed: the fundamental asymmetric stretch of the C₂D₂ component, two combination bands involving the out-of-plane torsional vibrations (C₂D₂ ν₃ + torsion and CO₂ ν₃ + torsion) for CO₂–C₂D₂, and two combination bands involving an intermolecular in-plane bending vibration for CO₂–C₂H₂ and CO₂–C₂D₂. The resulting intermolecular frequencies are 61.408(1), 54.5(5), 39.9(5), and 39.961(1) cm^?1 for CO₂–C₂H₂ and CO₂–C₂D₂ in-plane vibrations, and CO₂–C₂D₂ out-of-plane torsional vibrations in CO₂ and C₂D₂ regions, respectively. This is the first experimental determination of these intermolecular vibrational frequencies.     

A numerical investigation of the evolution of 2-D disturbances in hypersonic boundary layers and the effect on the flow structure due to the existence of shocklets

~~A numerical investigation of the evolution of 2-D disturbances in hypersonic boundary layers and the effect on the flow structure due to the existence of shocklets~~     

Magnitude of O(α2) corrections and search for new effects in the electroweak interactions

A quick method of calculating certain combinations of the O(α²) corrections in the electroweak theory is presented. The results agree with earlier explicit calculations of the O(α²) corrections to the vector boson masses and in other cases provide an estimate of the lower limits for such corrections. Some non-standard effects like heavy fermion or supersymmetric contributions are also discussed. Detailed calculations show that even in the case of the strong supersymmetric contribution, the new one-loop corrections are comparable to the two-loop ones in the standard model.     

Influence of the reagent vibration on the stereo-dynamics of the reactions D^- ＋ H2 and H^- ＋ D2

Employing the quasi-classical trajectory method and the potential energy surface of Panda and Sathyamurhy [Panda A N and Sathyamurthy N 2004 J.Chem.Phys.121 9343],the effect of the reagent vibration on vector correlation of the ion-molecule reactions D～-+H₂ and H～-+D₂ is studied at a collision energy of 35.7 kcal/mol.Four generalized polarization-dependent differential cross sections （2π/σ）（dσ 00 /dωt）,（2π/σ）（dσ 20 /dωt）,（2π/σ）（dσ 22+ /dωt）,and （2π/σ）（dσ 21 /dωt） are presented in the centre-of-mass reference frame,separately.At the same time,the effects on the product angular distributions P （θr）,P （φr） and P （θr,φr） of the title reactions are also analysed.The calculated results show that the scattering tendencies of the product HD,the alignment and the orientation of j sensitively depend on reagent molecule vibration.     

A theoretical study of the stereodynamics on the abstraction reactions H/D ＋ HS/DS

The quasi-classical trajectory(QCT) method is employed to calculate the stereodynamics of the abstraction reactions H/D+HS/DS based on an accurate potential energy surface [L S J,Zhang P Y,Han K L and He G Z 2012 J.Chem.Phys.136 094308].The reaction cross sections of the title reaction are computed,and the vector correlations for different collision energies and different initial vibrational states are presented.The influences of the collision energy and reagent vibration on the product polarization are studied,and the product polarizations of the title reactions are found to be distinctly different,which arises from the different mass factors,collision energies,and reagent vibrational states.     

Dynamical studies and product analysis of O(1D) + H2/D2 reactions

The aim of this study was to analyse the dynamics of O(¹D)?+?H₂/D₂ reactions using quasiclassical trajectory calculations on a double-valued potential energy surface for H₂O. Produced on the photodissociation of stratospheric ozone, the excited oxygen atom is a highly reactive species whose chemistry plays a key role in the ozone depletion cycle. In order to make comparisons with experiment, we studied these reactions at fixed translational collision energies. In particular, we consider the reactive cross sections, the thermal rate constants, the opacity function, and the differential cross sections. In addition, we also study the energy distribution of the products and compare the results with experiment and calculations based on phase space statistical theory. Results for the rotational population of the OH products are also compared with experimental results. The agreement between our results and experiment reinforces the accuracy of the H₂O potential energy surface used.     

A study of π states of H2 + in the one centre approach

The statistical theory of the elastic constants of nematic liquid crystals is applied to detailed calculations based on well-defined approximations for the direct correlation function of Ornstein and Zernike and for the singlet orientational distribution. The model of hard spherocylinders with superimposed r ^-6 attraction modulated by a Maier-Saupe P ₂(cos ?_{1 2}) term, is used. The dependence on temperature, on the order parameter and on the length to breadth ratio, of the reduced elastic constants K* _i (i=1, 2, 3), is discussed in some detail and comparison with experiment is included.     

A new method for the calculation of Sommerfeld screening parameter σ1 in x-ray spectra

The paper describes a new method for the calculation of the Sommerfeld screening parameter σ₁. It requires neither the knowledge of the energy separations of spin doublet levels nor is it based on the application of the Hertz law. The only data required for the calculation are the experimental energy values of the level concerned for the series of elements belonging to the same subshell in which the element in the question is situated. As an illustration the values of σ₁ are calculated for the L ₁, L ₂ and L ₃ levels for elements belonging to the 4f subshell and these are found to be in excellent agreement with those published earlier by Gokhale and Misra. The method brings out the constancy of σ₁ (L ₂ L ₃)−σ₁(L ₁) in a natural way and may thus be regarded as providing theoretical explanation of the Hertz law.     

A new luminescence detection and stimulation head for the Risø TL/OSL reader

A new automated Detection And Stimulation Head (DASH) has been developed for the Risø TL/OSL luminescence reader to provide easy access to new technologies, new signals and new measurement methods. The automated DASH includes a filter changer and a detector changer that makes it possible to change stimulation filters (4 × 4 filter combinations possible) and detectors (3 detectors possible) as part of a measurements sequence. The new automated DASH with dedicated driver electronics does not affect the use of other attachments, and can be retrospectively fitted to existing Risø TL/OSL readers.     

Isotopic effects of the N(2D) + H2 → NH + H reaction: a quantum time-dependent wave packet investigation

Based on the potential energy surface reported by Li and co-workers (J. Comput. Chem. 34 1686–1696 (2013)), the dynamics calculations of N(²D)?+?H₂(v ₀?=?0, j ₀?=?0) reaction and its isotopic variants HD and D₂ are studied using time-dependent wave packet method in the collision energy range of 0.01–1.0?eV. Dynamics properties such as reaction probability, differential cross section, and integral cross section are studied at state-to-state level of theory. Present values are compared with available theoretical and experimental results. The results indicate that the integral cross sections of N(²D)?+?D₂ reaction are in general good agreement with the experimental data at collision energy below 0.15?eV. The rotational state-resolved integral cross sections of N(²D)?+?H₂/HD/D₂ reactions are compared with experimental values for the first time, with the obtained values being in good agreement with the experimental data.     

Anisotropy and temperature dependence of the first critical field in 2H–NbS2

We report on μ$\mu$ Hall probe measurements on single crystals of 2H–NbS₂. This compound is the only superconducting 2H-dichalcogenide which does not develop a charge density wave. At low temperature and low magnetic field, a Bean profile is observed, allowing to evaluate the critical current. Moreover, the anisotropy and temperature dependence of the first critical field in 2H–NbS₂ was measured down to 1.2 K. A linear temperature dependence of the first penetration field is clearly observed. The absolute magnetic penetration depth is found to be 83 nm which is slightly reduced compared to the iso-structural compound 2H–NbSe₂.