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Low Order (low + order)
Selected AbstractsMultidimensional FEM-FCT schemes for arbitrary time steppingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2003D. Kuzmin Abstract The flux-corrected-transport paradigm is generalized to finite-element schemes based on arbitrary time stepping. A conservative flux decomposition procedure is proposed for both convective and diffusive terms. Mathematical properties of positivity-preserving schemes are reviewed. A nonoscillatory low-order method is constructed by elimination of negative off-diagonal entries of the discrete transport operator. The linearization of source terms and extension to hyperbolic systems are discussed. Zalesak's multidimensional limiter is employed to switch between linear discretizations of high and low order. A rigorous proof of positivity is provided. The treatment of non-linearities and iterative solution of linear systems are addressed. The performance of the new algorithm is illustrated by numerical examples for the shock tube problem in one dimension and scalar transport equations in two dimensions. Copyright © 2003 John Wiley & Sons, Ltd. [source] A study on the sorption of NO3, and F, on the carboxymethylated starch-based hydrogels loaded with Fe2+ ionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Ghanshyam S. Chauhan Abstract Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F, from water systems. The scheme was further applied for the removal of NO3, also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe2+ ions to generate anchorage for the anions. Sorption of Fe2+ was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe2+ uptake was loaded with the Fe2+ ions under optimum conditions and used for the sorption of F, and NO3,. High efficiency has been observed for F,, as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO3,, which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] The ,-adrenoceptor antagonist, zolertine, inhibits ,1D- and ,1A-adrenoceptor-mediated vasoconstriction in vitroAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 3 2000M. Ibarra 1 The antagonist effect of zolertine (4-phenyl-1-[2-(5-tetrazolyl)ethyl]piperazine trihydrochloride), on vascular contraction elicited by noradrenaline in aorta, carotid (,1D-adrenoceptors), mesenteric (,1A/D-adrenoceptors) and caudal arteries (,1A-adrenoceptors) from Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats and rabbit aorta (,1B-adrenoceptors), was investigated in endothelium-denuded arterial rings. 2 The selective ,1D-adrenoceptor agonist, noradrenaline, elicited concentration-dependent contractions in all arterial rings from both species. Noradrenaline selectivity was: carotid=aorta>>.Gt;mesenteric=rabbit aorta>caudal arteries. 3 The contractile responses induced by noradrenaline were competitively antagonized by zolertine in rat carotid and aorta arteries, yielding pA2 values of WKY, 7.48±0.18; SHR, 7.43±0.13 and WKY, 7.57±0.24; SHR, 7.40±0.08, respectively. Zolertine was a non-competitive antagonist in some blood vessels as Schild plot slopes were lower than unity. The pKb estimates for zolertine were WKY, 6.98±0.16; SHR, 6.81±0.18 in the mesenteric artery, WKY, 5.73±0.11; SHR, 5.87±0.25 in the caudal artery and 6.65±0.09 in rabbit aorta. 4 Competition binding experiments using the ,1-adrenoceptor antagonist [3H]prazosin showed a zolertine pKi of 6.81±0.02 in rat liver (,1B-adrenoceptors) and 6.35±0.04 in rabbit liver (,1A-adrenoceptors) membranes. 5 Zolertine showed higher affinity for ,1D-adrenoceptors compared to ,1A-adrenoceptors, while it had an intermediate affinity for ,1B-adrenoceptors. The ability of the ,1-adrenoceptor antagonist zolertine to block ,1D-adrenoceptor-mediated constriction in different vessels of WKY and SHR rats may explain its antihypertensive efficacy despite its low order of potency. [source] Identification of Time-Variant Modal Parameters Using Time-Varying Autoregressive with Exogenous Input and Low-Order Polynomial FunctionCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 7 2009C. S. Huang By developing the equivalent relations between the equation of motion of a time-varying structural system and the TVARX model, this work proves that instantaneous modal parameters of a time-varying system can be directly estimated from the TVARX model coefficients established from displacement responses. A moving least-squares technique incorporating polynomial basis functions is adopted to approximate the coefficient functions of the TVARX model. The coefficient functions of the TVARX model are represented by polynomials having time-dependent coefficients, instead of constant coefficients as in traditional basis function expansion approaches, so that only low orders of polynomial basis functions are needed. Numerical studies are carried out to investigate the effects of parameters in the proposed approach on accurately determining instantaneous modal parameters. Numerical analyses also demonstrate that the proposed approach is superior to some published techniques (i.e., recursive technique with a forgetting factor, traditional basis function expansion approach, and weighted basis function expansion approach) in accurately estimating instantaneous modal parameters of a structure. Finally, the proposed approach is applied to process measured data for a frame specimen subjected to a series of base excitations in shaking table tests. The specimen was damaged during testing. The identified instantaneous modal parameters are consistent with observed physical phenomena. [source] | ||||||||||