250 research outputs found
EXTRA HIGH ACCURACY FITTING OF THE PES FOR SUB-PERCENT CALCULATION OF INTENSITIES
No full textCalculation of rotation-vibration line intensities with sub-percent
accuracy has recently become a standard requirement for the
applications in retrieval and monitoring of gases in the Earth's
atmosphere and potentially in the atmospheres of exoplanets. A major
factor in the accurate calculation of intensities is the requirement
for a high accuracy \textit{ab initio} Dipole moment surface (DMS)
(e.g. references \footnote{L.Lodi, J. Tennyson and O.L. Polyansky, \textit{Journal of Chemical Physics}, \textbf{135}, 034113, (2011) } and \footnote{ O.L. Polyansky, K. Bielska, M. Ghysels, L. Lodi, N.F.Zobov, J.T.Hodges, J. Tennyson \textit{ Physical Review Letters}, \textbf{114}, 243001, (2015) }).
We demonstrate here that the change from
the ”good” potential energy surface (PES) to ”excellent” PES, used for the
intensity calculations is also important. By ”good” we mean here,
for example, the PES a standard deviation of 0.025 \wn and by
”excellent” - the PES with the standard deviation 0.011 \wn. Details of
studies on \chem{H_2O}\footnote{I.I Mizus, A.A. Kyuberis, N.F. Zobov, V.Y. Makhnev, O.L. Polyansky and J. Tennyson \textit{Phil. Trans. R. Soc. A}, \textbf{376}, 20170149, (2018)}, \chem{O_3} \footnote{O.L.Polyansky, N.F. Zobov, I.I Mizus, A.A. Kyuberis. L. Lodi and J. Tennyson \textit{JQSRT},\textbf{ 210}, 127-135 (2018)},
\chem{HCN} and \chem{CO_2} molecules will be presented in the talk
IMPORTANCE OF RELATIVISTIC CORRECTIONS TO THE SPECTRUM OF WATER AND HYDROGEN SULPHIDE
No full text[1] J. Tennyson, P. Barletta, M.A. Kosten, O.L. Polyansky and N.F. Zobov, Spectrochimica Acta A 58 (2002) 663. [2] H.M. Quiney, P. Barletta, G. Tarczay, A.G. Cs\'{a}sz\'{a}r, O.L. Polyansky and J.Tennyson, Chem. Phys. Lett. 344 (2001) 413.Author Institution: Department of Physics and Astronomy, University College London; Department of Theoretical Chemistry, E\""{o}tv\""{o}s UniversityThe importance of effects as small as minor relativistic corrections in theoretical predictions of energy levels can be as high as few wavenumbers [1]. Two-electron relativistic corrections to the ground-state electronic energy of water and hydrogen sulphide are determined at over 300 (250) geometries. The corrections include the two-electron Darwin term of the Coulomb-Pauli Hamiltonian, and the Gaunt and Breit corrections, calculated perturbationally using four-component variational Dirac-Hartree-Fock wavefunctions. Fitted relativistic correction surfaces are constructed and used with an accurate ab initio nonrelativistic Born-Oppenheimer potential to calculate vibrational and rotational levels. The calculations suggest that these two-electron relativistic corrections, which have so far been neglected in rovibrational calculations on light molecules, have a substantial influence on the ro-vibrational levels [2]. The effects considered have markedly different characteristics for the stretching and bending levels
Fitting of a PES for rovibrational calculations on
No full textS.A. Tashkun and P. Jensen, J. Mol. Spec., 165, 173-184 (1994). O.L. Polyansky, P. Jensen and J. Tennyson, J. Chem. Phys., 101, 7651-7657 (1994)Author Institution: Department of Physics and Astronomy, University College London; Physikaliach-Chemisches Institut, Justus-Lieting-Universit\""{a}t GiessenWe took the potential energy surface for the ground electronic state of constructed by Tashkun and using the MORBID Hamiltonian and computer program. We wished to fit this experimental date using the exact kinetic energy (EKE) operator. Initially, EKE calculations were not not possible due to the presence of holes in the surface. A better starting point for the fit was constructed using the method in Polyansky whereby MORBID and EKE calculations are combined. We then improved the surface by fitting it to available experimental data using an iterative least-squares fitting procedure. In the low-energy region ( ) the fitting was successful. Above apporximately the higher electronic state begins to peturb the vibrational energy levels of the ground state. We were unable to fit the surface well to the experimental date above . We aim to provide a surface which will give accurate rovibrational levels of
Spectrum of hot water in the 2000-4750 cm-1 frequency range
No full textAn emission spectrum recorded in an oxyacetylene torch [P.-F. Coheur, P.F. Bernath, M. Carleer, R. Colin, O.L. Polyansky, N.F. Zobov, S.V. Shirin, R.J. Barber, J. Tennyson, J. Chem. Phys. 122 (2005) 074307] is analyzed for the region covering stretching fundamentals and associated hot bands of water. Many lines could be assigned on the basis of previously determined energy levels. New assignments made with a new variational linelist allow a further 800 energy levels covering 15 vibrational states and rotations up to J = 32 to be assigned. A simultaneous re-analysis of previously reported sunspot absorption spectra leads to the assignment of 581 further lines in the L-band spectrum and 67 in the N-band spectrum. © 2006 Elsevier Inc. All rights reserved.info:eu-repo/semantics/publishe
The city of the crescent; with pictures of Harem life, or The turks in 1854. By Gordon O.L. Gordon Trenery, Esq. Author of "the morning Land" etc. etc. In two volumes London΄Charles J. skeet 10, king William street, Charing cross. 1855.
No full textPreface: by Trenery CordonDedication:Content description: Detailed contentsIllustration: 2 (Views ,)Pagination: PP16+303P, PP10+309+1PPVolumes: 2Text Genre:ProseEpilogue: as conclusion at the last chapterIllustration: 2 (τοπία ,
Near-Infrared water lines in V838 Monocerotis
No full textEmploying spectra obtained with the new Keck I HIRES near-UVsensitive detector, we have performed a comprehensive chemical composition analysis of the binary blue metal-poor star CS 29497-030. Abundances for 29 elements and upper limits for an additional seven have been derived, concentrating on elements largely produced by means of neutron-capture nucleosynthesis. Included in our analysis are the two elements that define the termination point of the slow neutron-capture process, lead and bismuth. We determine an extremely high value of [Pb/Fe] = +3.65 ± 0.07 ( = 0.13) from three features, supporting the single-feature result obtained in previous studies. We detect Bi for the first time in a metal-poor star. Our derived Bi/Pb ratio is in accord with those predicted from the most recent FRANEC calculations of the slow neutron-capture process in low-mass asymptotic giant branch (AGB) stars. We find that the neutron-capture elemental abundances of CS 29497-030 are best explained by an AGB model that also includes very significant amounts of pre-enrichment of rapid neutron-capture process material in the protostellar cloud out of which the CS 29497-030 binary system formed. Mass transfer is consistent with the observed [Nb/Zr] 0. Thus, CS 29497-030 is both an r+s and "extrinsic AGB" star. Furthermore, we find that the mass of the AGB model can be further constrained by the abundance of the light odd-element Na
An approximate solution of loaded hyperbolic equation with homogenios boundary conditions
No full textО.Л. Бозиев,
Институт информатики и проблем регионального управления
Кабардино-Балкарского научного центра РАН, г. Нальчик, Российская Федерация
E-mail: [email protected]. O.L. Boziev
Institute of Computer Science and Problems of Regional Management of KBSC
of the Russian Academy of Sciences, Nal'chik, Russian Federation
E-mail: [email protected]Получена формула приближенного решения начально-краевой задачи
для нагруженного гиперболического уравнения, для нахождения которого
используется априорная оценка решения поставленной задачи. The article proposes a method for solving hyperbolic equation with a spatial variable integral of the
natural powers of the unknown function modulus, whereby it is loaded. The author considers an initial
boundary value problem with homogeneous boundary conditions. Scalar products of the equation by
various functionals and subsequent conversions make it possible to obtain a priori estimates of solutions
of the problem in various spaces. By successive integration over the spatial variable the reduction to an
ordinary differential equation associated with the initial one is produced. Its approximate solution is
sought using a priori estimates that are obtained. Found function leads to the formula that expresses the
approximate solution to the original problem through the right parts of the initial conditions
Opacity data for HCN and HNC from a new ab initio line list
No full textA new extensive ab initio rotation-vibration HCN/HNC line list is presented. The line list contains rotation-vibration energy levels, line frequencies, and line strengths for transitions between states with energy less than 18,000 cm-1 and with J≤60. This line list greatly improves the quality and range of HCN/HNC data available. It is presently the most extensive and most accurate ab initio HCN/HNC line list in existence. It is hoped that this data set will be used in models of C star atmospheres and elsewhere
Ab initio rotation–vibration spectra of HCN and HNC
No full textWe have calculated an ab initio HCN/HNC linelist for all transitions up to J=25 and 18 000 cm−1 above the zero point energy. This linelist contains more than 200 million lines each with frequencies and transition dipoles. The linelist has been calculated using our semi-global HCN/HNC VQZANO+PES and dipole moment surface, which were reported in van Mourik et al. (J. Chem. Phys. 115 (2001) 3706). With this linelist we synthesise absorption spectra of HCN and HNC at 298 K and we present the band centre and band transition dipoles for the bands which are major features in these spectra. Several of the HCN bands and many of the HNC bands have not been previously studied. Our line intensities reproduce via fully ab initio methods the unusual intensity structure of the HCN CN stretch fundamental (0001) for the first time and also the forbidden (0220) HCN bending overtone. We also compare the J=1→0 pure rotational transition dipole in the HCN/HNC ground and vibrationally excited states with experimental and existing ab initio results
Robust model-based optimization of evacuation guidance
No full textLarge scale disasters, such as floods and fires, cause many casualties. This risk of casualties is reduced by evacuating the people from the threatened region. By guiding these people, i.e. instructing them when and where to go, the efficiency of the evacuation is increased. This means that, for example, the time needed for the evacuation is reduced. This thesis discusses the literature on optimization methods for car-based evacuation guidance. While many optimization methods are developed, the attention for uncertainty and compliance behavior in these methods is limited. This while these factors are of great importance for evaluating guidance in a realistic way. These findings are the reason to ask the following question: How can evacuation guidance be optimized in an efficient way, while incorporating uncertainty and compliance behavior? This thesis answers this question by formulating problems, presenting solution approaches and analyzing the results of case studies. The problem formulations contain decision variables representing guidance, consisting of departure time, route, and destination instructions for all evacuees. An objective function expresses the performance of this guidance. A travel behavior model and a traffic propagation model are included in the problem formulation to evaluate the guidance resulting in the performance value. The formulations and approaches are flexible with respect to the modeling assumptions. This is important because of the high degree of development of evacuation models. The first specific problem formulation presented in this thesis incorporates compliance behavior in the optimization of evacuation guidance. This problem is solved by a metaheuristic based on ant colony optimization. The method is applied to develop evacuation guidance for a hypothetical flood of part of The Netherlands. This case study shows that the optimized guidance increases the evacuation efficiency compared to no guidance or guidance developed by simple rules. This can be explained by the spread of travelers over time and space. The case study also shows that the solution approach results in a solution which effectiveness is close to the effectiveness of the optimal solution. The problem formulation is extended such that all kinds of uncertainty, like uncertainty in the demand, the behavior and the capacity, can be incorporated. This formulation is based on scenarios, which are representations of the uncertainty. Two procedures to select these scenarios are proposed, i.e. a deterministic procedure which results in a set of scenarios that is constant over the iterations of the solution approach, and a stochastic procedure that results in varying scenarios over the iterations. A case study shows the usefulness of incorporating uncertainty in the evacuation problem. For most cases holds that the efficiency of the evacuation increases when uncertainty is incorporated. The case study also shows that incorporating uncertainty is computationally demanding. Solving the evacuation problem is computationally expensive because of a high number of decision variables and high evaluation costs. A fixed-point approach is presented that efficiently optimizes evacuation guidance, in particular route guidance. This approach decomposes the original problem into simpler problems that are iteratively solved resulting in an approximate solution to the original problem. This approach overcomes the difficulties associated with the original problem. A case study shows that the fixed-point approach substantially speeds up the optimization of route guidance, while maintaining a comparable effectiveness of the resulting guidance. This thesis gives new insights in how beneficial evacuations are and how realistic plans can be optimized efficiently. The presented methods are ready for use in practice regarding the development of car-based evacuation guidance. Guidance can be optimized and, if available, it can be compared with existing plans. The guidance will be part of a broader plan that includes, for example, evacuation by public transport and communication and operation strategies.Transport & PlanningCivil Engineering and Geoscience
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