Quasi-planar steep water waves

A new description for highly nonlinear potential water waves is suggested, where weak 3D effects are included as small corrections to exact 2D equations written in conformal variables. Contrary to the traditional approach, a small parameter in this theory is not the surface slope, but it is the ratio of a typical wave length to a large transversal scale along the second horizontal coordinate. A first-order correction for the Hamiltonian functional is calculated, and the corresponding equations of motion are derived for steep water waves over an arbitrary inhomogeneous quasi-1D bottom profile.Comment: revtex4, 4 pages, no figure

Molecular line opacity of LiCl in the mid-infrared spectra of brown dwarfs

We present a complete line list for the X 1Sigma+ electronic ground state of LiCl computed using fully quantum-mechanical techniques. This list includes transition energies and oscillator strengths in the spectral region 0.3-39,640.7 cm-1 for all allowed rovibrational transitions in absorption within the electronic ground state. The calculations were performed using an accurate hybrid potential constructed from a spectral inversion fit of experimental data and from recent multi-reference single- and double-excitation configuration interaction calculations. The line list was incorporated into the stellar atmosphere code PHOENIX to compute spectra for a range of young to old T dwarf models. The possibility of observing a signature of LiCl in absorption near 15.8 microns is addressed and the proposal to use this feature to estimate the total lithium elemental abundance for these cool objects is discussed.Comment: 8 pages, 2 figures, 1 table. Accepted for publication in ApJ 613, Sept. 20 200

A study of the macro-invertebrates of Lakes Naivasha, Oloidien and Sonachi, Kenya

Des prélèvements de macro-invertébrés ont été faits dans le lac Naivasha en décembre-janvier 1982-83 et en juillet-août 1984, et dans les deux lacs avoisinants, Oloidien et Sonachi, seulement en 1984. On a remarqué une différence considérable dans les listes faunistiques obtenues au cours des deux visites. La comparaison avec les listes obtenues par les expéditions de Percy Sladen (1929) and Cambridge (1930-31) a aussi révélé un changement majeur à long terme, y compris un changement complet des faunes d'oligochètes et de mollusques. Le changement à court terme de 1982/83 à 1984 est attribué aux importantes fluctuations naturelles du niveau de l'eau. Parmi les autres facteurs qui ont pu causer les changements à long terme, on cite la disparition des macrophytes submergés, broutés par des espèces introduites, Coypou (#Myocaster coypus) et écrevisse (#Procambarus Clarkii), l'introduction des espèces étrangères et des pratiques agricoles entraînant l'enlèvement d'une grande quantité de papyrus et l'emploi toujours croissant de l'eau du lac pour l'irrigation. (Résumé d'auteur

Topological Optimization of the Evaluation of Finite Element Matrices

We present a topological framework for finding low-flop algorithms for evaluating element stiffness matrices associated with multilinear forms for finite element methods posed over straight-sided affine domains. This framework relies on phrasing the computation on each element as the contraction of each collection of reference element tensors with an element-specific geometric tensor. We then present a new concept of complexity-reducing relations that serve as distance relations between these reference element tensors. This notion sets up a graph-theoretic context in which we may find an optimized algorithm by computing a minimum spanning tree. We present experimental results for some common multilinear forms showing significant reductions in operation count and also discuss some efficient algorithms for building the graph we use for the optimization

Numerical modeling of quasiplanar giant water waves

In this work we present a further analytical development and a numerical implementation of the recently suggested theoretical model for highly nonlinear potential long-crested water waves, where weak three-dimensional effects are included as small corrections to exact two-dimensional equations written in the conformal variables [V.P. Ruban, Phys. Rev. E 71, 055303(R) (2005)]. Numerical experiments based on this theory describe the spontaneous formation of a single weakly three-dimensional large-amplitude wave (alternatively called freak, killer, rogue or giant wave) on the deep water.Comment: revtex4, 8 pages, 7 figure

Evaluation of the optical switching characteristics of erbium-doped fibres for the development of a fibre Bragg grating sensor interrogator

A polling topology that employs optical switching based on the properties of erbium-doped fibres (EDFs) is used to interrogate an array of FBGs. The properties of the EDF are investigated in its pumped and un-pumped states and the EDFs’ switching properties are evaluated by comparing them with a high performance electronically controlled MEM optical switch. Potential advantages of the proposed technique are discussed. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Reka bentuk untuk kestabilan struktur

Buku ini mengandungi beberapa bab iaitu kandungan: kata penghantar, prakata, tatatanda, bab 1 tabii ketakstabilan, pengenalan, bab 2 ketakstabilan sesatah bagi tiang, pengenalan, lengkokan euler keseluruhan, tiang berhujung-cemat sempurna – pendekatan klasik, lengkungan awal dalam tiang berhujung-cemat tiang dikenakan beban sisi-tiang rasuk, tiang berbeban sipi, tegasan di dalam tiang bergeometri taksempurna, tegasan baki, tiang terpencil sebenar dan kod rekabentuk, keadaan hujung tiang, fungsi kestabilan, anggota prisma tanpa huyung, anggota prisma berhuyung, anggota tak-prisma, perembat, bibliografi, bab 3 lengkokan sisi bagi rasuk, pengenalan, piuhan keratan-i, lengkokan rasuk, runtuhan rasuk ‘nyata’, penggunaan teori lengkokan sisi terhadap rekabentuk rasuk, kesan dari momen tak-segaya, kegunaan faktor–m di dalam rekabentuk, kesan tahap pengenaan beban melintang, kesan dari keadaan sokong hujung, kelakuan rasuk selanjar, halangan sisi berkesan, rasuk jalur, kesan lengkokan tempatan, rasuk selain dari keratan-i seragam berbebibir-sama, bibliografi, bab 4 beban genting anjal bagi kerangka satah, pengenalan, kelakuan kerangka dan ketakstabilan kerangka, beban genting anjal bagi kerangka kerja tanpa huyung: teknik corak momen, beban genting anjal bagi kerangka kerja tanpa huyung: teknik santaian winter, beban genting anjal bagi kerangka kerja tanpa huyung: teknik kerangka gantian bolton, beban genting anjal bagi kerangka kerja tanpa huyung: portal terembat, pendekatan ‘agihan kekukuhan’ wood, beban genting anjal bagi kerangka kerja huyung: fungsi tiada-ricih n dan o, beban genting anjal bagi kerangka kerja huyung: teknik corak momen, beban genting anjal bagi kerangka kerja huyung: teknik santaian winter, beban genting anjal bagi kerangka kerja huyung: kaedah wood, beban genting anjal bagi kerangka kerja huyung: kaedah horne, beban genting anjal dan rekabentuk kerangka, bibliografi, lampiran serta indeks

The Molecular Line Opacity of MgH in Cool Stellar Atmospheres

A new, complete, theoretical rotational and vibrational line list for the A-X electronic transition in MgH is presented. The list includes transition energies and oscillator strengths for all possible allowed transitions and was computed using the best available theoretical potential energies and dipole transition moment function with the former adjusted to account for experimental data. The A-X line list, as well as new line lists for the B'-X and the X-X (pure rovibrational) transitions, were included in comprehensive stellar atmosphere models for M, L, and T dwarfs and solar-type stars. The resulting spectra, when compared to models lacking MgH, show that MgH provides significant opacity in the visible between 4400 and 5600 Angstrom. Further, comparison of the spectra obtained with the current line list to spectra obtained using the line list constructed by Kurucz (1993) show that the Kurucz list significantly overestimates the opacity due to MgH particularly for the bands near 5150 and 4800 Angstrom with the discrepancy increasing with decreasing effective temperature.Comment: 10 pages, 4 figures, 3 table