1,332 research outputs found
ExoMol line lists - III. An improved hot rotation-vibration line list for HCN and HNC
No full textA revised rotation-vibration line list for the combined hydrogen cyanide (HCN)/hydrogen isocyanide (HNC) system is presented. The line list uses ab initio transition intensities calculated previously and extensive data sets of recently measured experimental energy levels. The resulting line list has significantly more accurate wavelengths than previous ones for these systems. An improved value for the separation between HCN and HNC is adopted, leading to an approximately 25 per cent lower predicted thermal population of HNC as a function of temperature in the key 2000 to 3000 K region. Temperature-dependent partition functions and equilibrium constants are presented. The line lists are validated by comparison with laboratory spectra and are presented in full as supplementary data to the article and at www.exomol.com
ExoMol line lists-IV. The rotation-vibration spectrum of methane up to 1500 K
No full textA new hot line list is calculated for CH in its ground electronic state. This line list, called 10to10, contains 9.8 billion transitions and should be complete for temperatures up to 1500 K. It covers the wavelengths longer than 1 μm and includes all transitions to upper states with energies below hc · 18 000 cm and rotational excitation up to J = 39. The line list is computed using the eigenvalues and eigenfunctions of CH obtained by variational solution of the Schrödinger equation for the rotation-vibration motion of nuclei employing program TROVE and a new 'spectroscopic' potential energy surface (PES) obtained by refining an ab initio PES (CCSD(T)-F12c/aug-cc-pVQZ) through least-squares fitting to the experimentally derived energies with J = 0-4 and a previously reported ab initio dipole moment surface (CCSD(T)-F12c/aug-cc-pVTZ). Detailed comparisons with other available sources of methane transitions including HITRAN, experimental compilations and other theoretical line lists show that these sources lack transitions both higher temperatures and near-infrared wavelengths. The 10to10 line list is suitable for modelling atmospheres of cool stars and exoplanets. It is available from the CDS data base as well as at www.exomol.com
The Darby-Lewis dataset for 9Be2H
No full textThe dataset is an archive of ExoMol page, https://exomol.com/data/molecules/BeH/9Be-2H/Darby-Lewis. Please check the reference details according to the following description or directly from the website.Definitions file:9Be-2H__Darby-Lewis.defRoot references for ExoMol database: 1. J. Tennyson, S.N. Yurchenko A.F. Al-Refaie, V.H.J. Clark, K.L. Chubb,E.K. Conway, A. Dewan, M.N. Gorman, C. Hill, A.E. Lynas-Gray, T. Mellor, L.K. McKemmish, A. Owens, O.L. Polyansky, M. Semenov, W. Somogyi, G. Tinetti, A. Upadhyay, I. Waldmann, Y. Wang, S. Wright and O.P. Yurchenko, The 2020 release of the ExoMol database: molecular line lists for exoplanet and other hot atmospheres, J. Quant. Spectrosc. Rad. Transf., 255, 107228 (2020).[https://doi.org/10.1016/j.jqsrt.2020.107228.]Darby-Lewis: line listDarby-Lewis line list for BeH in its X and A electronic states using the Duo program.: 9Be-2H__Darby-Lewis.trans.bz2 Transition file for the Darby-Lewis line list for (9Be)(2H) 9Be-2H__Darby-Lewis.states.bz2 States file for the Darby-Lewis line list for (9Be)(2H)References: 1. Darby-Lewis, D., Tennyson, J., Lawson, K. D., Yurchenko, S. N., Stamp, M. F., Shaw, A., Brezinsek, S., JET Contributors, "Synthetic spectra of BeH, BeD and BeT for emission modeling in JET plasmas", J. Phys. B At. Mol. Opt. Phys. 51, 185701 (2018). [https://doi.org/10.1088/1361-6455/aad6d0][18DaTeLa.BeH]Darby-Lewis: partition functionDarby-Lewis line list for BeH in its X and A electronic states using the Duo program.: 9Be-2H__Darby-Lewis.pf Partition function of (9Be)(2H) generated using the Darby-Lewis line listReferences: 1. Darby-Lewis, D., Tennyson, J., Lawson, K. D., Yurchenko, S. N., Stamp, M. F., Shaw, A., Brezinsek, S., JET Contributors, "Synthetic spectra of BeH, BeD and BeT for emission modeling in JET plasmas", J. Phys. B At. Mol. Opt. Phys. 51, 185701 (2018). [https://doi.org/10.1088/1361-6455/aad6d0][18DaTeLa.BeH
Influence of predefined angle of attack on piezoelectric energy harvesting from transverse galloping of different bluff bodies
No full textThe development of smart Internet-of-Things (IoT) solutions requires sensor nodes to be placed at different locations of monitored structures. Wireless solutions are quite attractive because of their simplicity although requiring for local energy supply. In this context, this study investigates the influences of the predefined angle of attack on the piezoelectric energy harvesting based on transverse galloping of different bluff bodies. The investigation is based on a lumped electro-aero-mechanical model with linear electrical and mechanical properties and nonlinear aerodynamic forces evaluated using the quasi-steady theory. The performances of energy harvesters with six different bluff bodies are analyzed at various predefined angles of attack: four rectangular cross-sections with different width-to-height ratios (i.e., b/d), one trapezium section, and one equal angle section. The main purpose is to understand the sensitivity of various bluff body-based energy harvesters on the predefined angle of attack, and further suggest a bluff body-based energy harvester that is robust to the predefined angle of attack. The results show that the response is quite dependent on the characteristic of the electro-mechanical system and the bluff body cross-section and angle of attack. In all cases, the load resistance should be tuned to maximize energy production. The largest vibration amplitude (i.e., largest power output) is predicted for the rectangular bluff body with b/d = 1.0 at a 0° angle of attack. However, its performances are quite dependent on the angle of attack, resulting in a zero-power output for an angle of attack exceeding 4°. A rectangular bluff body with b/d within 1.62 to 2.5 exhibits a reduced energy production compared with b/d = 1.0 at a 0° angle of attack but better robustness varying the angle of attack. Finally, the trapezium and the angle bluff bodies are not suitable for energy harvesting due to their very high onset velocities within the considered range of angles of attack
Exomol: molecular line list for exoplanets and other atmospheres
No full textThe discovery of extrasolar planets is one of the major scientific
advances of the last two decades. Thousands of planets have now been
detected and astronomers are beginning to characterize their
composition and physical characteristics. To do this requires a huge
quantity of spectroscopic data most of which are not available from
laboratory studies. The ExoMol project [1] is generating a
comprehensive solution to this problem by providing spectroscopic
data on all the molecular transitions of importance in the
atmospheres of exoplanets. These data are widely applicable to other
problems such studies on cool stars, brown dwarfs and circumstellar
environments as well as industrial and technological problems on earth.
ExoMol employs a mixture of first
principles and empirically tuned quantum mechanical methods
to compute comprehensive and very large rotation–vibration and
rovibronic line lists. Results span a variety of closed
(NaH, SiO, PN, NaCl, KCl, CS) and open (BeH, MgH, CaH, AlO, VO) shell
diatomics to triatomics (HCN/HNC, SO, HS, H),
tetratomics (HCO, PH, SO, HO), plus methane [2] and nitric acid [3]. This has led directly to the detection of new species
in the atmospheres of exoplanets [4]. A new comprehensive
data release has just been completed [5]. Progress on and future
prospects of the project will be summarised.
\bibliographystyle{default}
\begin{thebibliography}{5}
\bibitem{jt528} J. Tennyson, S.~N. Yurchenko, Mon. Not. R. astr. Soc., 425, 21, 2012.
\bibitem{jt572} S.~N. Yurchenko, J. Tennyson, J. Bailey, M.~D.~J. Hollis, G Tinetti, Proc. Nat. Acad. Sci., 111, 9379, 2014.
\bibitem{jt614} A.~I. Pavlyuchko, S.~N. Yurchenko, J. Tennyson, Mon. Not. R. astr. Soc., 452, 1702, 2015.
\bibitem{jt629} A. Tsiaras {\it et al}, Astrophys. J., in press.
[5] J. Tennyson {\it et al}, J. Mol. Spectrosc., in press.
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Previous issue date: 2016-06-2
A predicted optimal performance of the Yurchenko layout vault in women's artistic gymnastics
No full textThe Yurchenko layout vault is the base vault from which more advanced forms of the Yurchenko family of vaults have evolved. The purpose of the study was to predict an individual's optimal Yurchenko layout vault by modifying selected critical mechanical variables. The gymnast's current performance characteristics were determined using the Peak-Motus video analysis system. Body segment parameters were determined using the elliptical zone mathematical modeling technique of Jensen (1978). A 5-segment computer simulation model was personalized for the gymnast comprising the hands, upper limbs, upper trunk, lower trunk, and lower limbs. Symmetry was assumed, as the motion was planar in nature. An objective function was identified which translated the subjective points-evaluation scheme of the Federation of International Gymnastics (FIG) Code of Points to an analytic expression that was mathematically tractable. The objective function was composed of performance variables that, if maximized, would result in minimal points being deducted and bonus points being allocated. A combined optimal control and optimal parameter selection approach was applied to the model to determine an optimum technique. The predicted optimal vault displayed greater postflight amplitude and angular momentum when compared with the gymnast's best trial performance. Increased angular velocity, and consequently greater angular momentum at impact and greater shoulder flexion angle at impact with the horse, were related with this optimum technique. The impact phase therefore serves to increase the angular momentum during horse contact. Since the optimized parameters at impact with the horse were within the accepted physical capacity limits observed for the individual, the predicted vault is viable.Griffith Health FacultyNo Full Tex
On energy harvesting from a vibro-impact oscillator with dielectric membranes
No full textA vibro-impact mechanical system comprising of a ball moving freely between two dielectric membranes located at a certain distance from each other is studied. The system generates electricity when the ball moving due ambient vibrations impacts one of the membranes. The energy harvesting principle of the proposed system is explained and then used to formulate a numerical model for estimating the system output voltage. The dynamic behavior and output performance of the system are thoroughly studied under a harmonic excitation, as well as different initial conditions and various values of the restitution coefficient of the membranes. The delivered research results are useful for selecting the system parameters to achieve its optimal output performance in a realistic vibrational environment. Potential application of the proposed system for energy harvesting from car engine vibrations is presented
Trypanosomatids are common and diverse parasites of Drosophila
No full textDrosophila melanogaster is an important model system of immunity and parasite resistance, yet most studies use parasites that do not naturally infect this organism. We have studied trypanosomatids in natural populations to assess the prevalence and diversity of these gut parasites. We collected several species of Drosophila from Europe and surveyed them for trypanosomatids using conserved primers for two genes. We have used the conserved GAPDH sequence to construct a phylogenetic tree and the highly variable spliced leader RNA to assay genetic diversity. All 5 of the species that we examined were infected, and the average prevalence ranged from 1 to 6%. There are several different groups of trypanosomatids, related to other monoxenous Trypanosomatidae. These may represent new trypanosomatid species and were found in different species of European Drosophila from different geographical locations. The detection of a little studied natural pathogen in D. melanogaster and related species provides new opportunities for research into both the Drosophila immune response and the evolution of hosts and parasites.</p
PREDICTION OF AN OPTIMUM TECHNIQUE FOR THE WOMEN’S YURCHENKO LAYOUT VAULT
No full textThe purpose of this study was to identify an optimum technique for the women’s Yurchenko layout vault through an application of optimal control theory on a five-segment model consisting of the hand, whole arm, upper trunk, lower trunk and whole leg. An optimum technique for the vault was determined which, compared to the data, had greater post-flight amplitude and a better layout posture throughout post-flight. However, it involved a larger angular velocity of the segments and greater shoulder extension by about 9º, than the data. The impact phase of the optimum technique was shorter than the data by 0.003 s, and served to increase both the angular momentum of the model as well as the vertical horse takeoff velocity. There is thus, evidence of a ‘blocking technique’ during impact
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