Distribution by Scientific Domains

Selected Abstracts

Electronic Structure of Linearly Coordinated EQ Complexes of the Type [(N3N)W(EQ)] [N3N = N(CH2CH2NSiMe3)3; E = P, As, Sb, Bi; Q = O, S, Se, Te]: A DFT Study

Gábor Balázs
Abstract Density functional theory (DFT) calculations were carried out on the terminal EQ complexes [(N3N)W(EQ)] {N3N = N(CH2CH2NSiMe3)3; E = P, As, Sb, Bi; Q = O, S, Se Te} to clarify the bonding situation within the linear Nax,W,E,Q core. This unusual structural motif gives rise to a bonding arrangement in which the ,-electron density is delocalised over the three atoms of the W,E,Q unit. Fragment calculations and natural bond order (NBO) data indicated that the ,-bonding component of the Nax,W,E,Q unit comprises two occupied , orbitals, while the , component of bonding comprises two sets of degenerate , orbitals. In general, the , orbitals of the Nax,W,E,Q core are higher in energy compared to the , orbitals. The phosphorus monoxide (EQ = PO) complexes provide an exception to this rule, with the 1, orbitals of the W,P,O core lower in energy than the , orbitals. Generally, as the atomic number of either the pnicogen (E) or chalcogen (Q) atom increases the extent of ,-orbital delocalisation decreases, whereas the ,-orbital delocalisation increases. Fractional bond orders and Wiberg bond indices were used to establish whether localisation of the ,-electron density gives rise to a W,E or an E,Q double or triple bond. Both methods indicate a W,E as well as an E,Q double bond. The ionic nature of the complexes were analysed by inspection of the Hirschfeld charge distribution which shows only a moderate ionic character. Exceptions are the pnicogen monoxide complexes, which are more ionic. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Validity, reliability, and responsiveness of the EQ-5D in inflammatory bowel disease in Germany

Renee G. Stark MD
Abstract Background: The EuroQol (EQ)-5D questionnaire is a generic instrument measuring health-related quality of life. Its validity, reliability, and responsiveness were assessed in a large sample of Crohn's disease (CD) and ulcerative colitis (UC) patients. Methods: The EQ-5D was completed initially (270 CD and 232 UC subjects) and after 4 weeks (447 subjects) with a transition question rating health change. Responsiveness of EQ visual analog scale (EQ-VAS) and the United Kingdom (UK-index) and German EQ-5D index (EQ-index) scores to reported changes in health was evaluated by standardized response means (SRM) and meaningful differences (MDs). Results: EQ-VAS and EQ-index scores correlated well with disease activity indices and differed significantly between active disease and remission groups. All scores were reliable in test,retest (ICC: EQ-VAS: 0.89; UK-index: 0.76; German EQ-index: 0.72). According to SRM, EQ-VAS was more responsive for deterioration in health than for improvement in health and was more responsive than index scores. Index scores were most responsive for deterioration in health in subjects in remission and for improved health in subjects with active disease. MDs for improved health (EQ-VAS: 10.9; UK EQ-index: 0.076; German EQ-index: 0.050) and deteriorated health (EQ-VAS: ,14.4; UK EQ-index: ,0.109; German EQ-index: ,0.067) were significant, but MD of EQ-VAS also differed significantly according to disease activity. Conclusions: The EQ-5D generates valid, reliable, and responsive preference-based valuations of health in CD and UC. EQ-VAS scores were more responsive than EQ-5D index scores. Thus, small health differences that are important from the patient's perspective may not be reflected in the EQ-index. Inflamm Bowel Dis 2010 [source]

Mössbauer spectroscopic studies of the six-coordinate heme,nitric oxide complex of iron(III) octaethylporphyrin N -methylimidazole, the first model of the nitrophorin,no complexes

Volker Schünemann
The NO, N -methylimidazole complex of isotopically enriched octaethylporphyrinatoiron(III) chloride, [OEP57Fe(NO)(N-MeIm)+Cl, has been prepared in dimethylacetamide solution and studied by low-temperature Mössbauer spectroscopy in the presence and absence of a magnetic field. This complex is a model for the Fe(III)-NO complexes of the nitrophorins of the blood-sucking insect, Rhodnius prolixus, where NO is released from the histidine-coordinated ferrihemin center of each of the proteins upon the insect's injection of the saliva into the victim. The [OEPFe(NO)(N -MeIm)]+Cl, complex is EPR silent and behaves as a diamagnetic species, with quadrupole splitting ,EQ = 1.64 mm s,1, asymmetry parameter , = 0.4, isomer shift , = 0.02 mm s,1, and linewidth ,= 0.3 mm s,1. Two electron configurations, Fe(III)-NO (low-spin d5, strongly antiferromagnetically coupled to NO), or Fe(II)-NO+ (low-spin d6, purely diamagnetic), are possible. Which is the actual configuration cannot be determined until detailed molecular calculations are carried out. The low-spin OEPFe(III)-bis- N -methylimidazole complex also present in this sample has EPR g-values, quadrupole splitting, isomer shift, and hyperfine splittings typical of rhombic low-spin ferriheme centers. [source]

Sensitivity analysis in oxidation ditch modelling: the effect of variations in stoichiometric, kinetic and operating parameters on the performance indices

A Abusam
Abstract This paper demonstrates the application of the factorial sensitivity analysis methodology in studying the influence of variations in stoichiometric, kinetic and operating parameters on the performance indices of an oxidation ditch simulation model (benchmark). Factorial sensitivity analysis investigates the sensitivities in a region rather than in a point. Hence, it has the advantage of giving more information about parameter interactions (non-linearity). Short-term results obtained have shown the following. The index AE is not significantly affected by variations in the value of parameters of the activated sludge model (ASM) No 1. The index TSP is greatly influence by heterotrophic yield (YH), heterotrophic decay (bH) and specific hydrolysis (kh) and the index EQ is dominated by YH, Monod coefficient (KS), bH, kh, anoxic condition correction factors (,g, ,h), hydrolysis half-saturation coefficient (KX), autotrophs maximum specific growth rate (µA) and ammonia half-saturation coefficient (KNH). Furthermore, the index EQ has been shown to be very sensitive to parameter interactions, at certain regions. © 2001 Society of Chemical Industry [source]

Food energy content influences food portion size estimation by nutrition students

C. C. Japur
Abstract Background:, Food portion size estimation involves a complex mental process that may influence food consumption evaluation. Knowing the variables that influence this process can improve the accuracy of dietary assessment. The present study aimed to evaluate the ability of nutrition students to estimate food portions in usual meals and relate food energy content with errors in food portion size estimation. Methods:, Seventy-eight nutrition students, who had already studied food energy content, participated in this cross-sectional study on the estimation of food portions, organised into four meals. The participants estimated the quantity of each food, in grams or millilitres, with the food in view. Estimation errors were quantified, and their magnitude were evaluated. Estimated quantities (EQ) lower than 90% and higher than 110% of the weighed quantity (WQ) were considered to represent underestimation and overestimation, respectively. Correlation between food energy content and error on estimation was analysed by the Spearman correlation, and comparison between the mean EQ and WQ was accomplished by means of the Wilcoxon signed rank test (P < 0.05). Results:, A low percentage of estimates (18.5%) were considered accurate (±10% of the actual weight). The most frequently underestimated food items were cauliflower, lettuce, apple and papaya; the most often overestimated items were milk, margarine and sugar. A significant positive correlation between food energy density and estimation was found (r = 0.8166; P = 0.0002). Conclusions:, The results obtained in the present study revealed a low percentage of acceptable estimations of food portion size by nutrition students, with trends toward overestimation of high-energy food items and underestimation of low-energy items. [source]

Differentiating emotional intelligence in leadership

Carina Fiedeldey-Van Dijk
Leadership has received considerable attention since the 1990s. We claim that leaders can be found at all levels of employment, and at the very least, all managers are expected to be leaders. Yet managerial status does not guarantee leadership. Leadership is a necessary component of and a filter for successful management. Effective managers demonstrate leadership capabilities. Leadership attributes are well captured in measures of emotional intelligence (EQ). Hence, leadership can improve if managers work to develop their EQ. We show how EQ, and hence leadership, can vary by level of employment among a composite international group of 3,305 employees with the Six Seconds Emotional Intelligence Assessment. The relationship between six leadership groups, as based on their EQ performance, across different employment levels was statistically examined, suggesting that leadership is realized in different ways depending on level of employment. It appears that employees become more skillful in emotional literacy and consequential thinking as they progress up the employment ladder. Intrinsic motivation and optimism are best leveraged by nonmanagerial rather than senior employees. The diminishing incorporation of empathy with an increase in employment level seems to stand in sharp contrast. Nonmanagerial employees, specialists, and entrepreneurs will benefit from developing their competence in pursuing their objectives with an overarching sense of purpose. The finding that high-EQ leaders seem to dominate in the managerial levels may be viewed as encouraging. [source]

Zoledronic acid improves femoral head sphericity in a rat model of perthes disease

David G. Little
Abstract We hypothesized that the bisphosphonate zoledronic acid (ZA) could improve femoral head sphericity in Perthes disease by changing the balance between bone resorption and new bone formation. This study tests the effect of ZA in an established model of Perthes disease, the spontaneously hypertensive rat (SHR). One hundred and twenty 4-week old SHR rats were divided into three groups of 40: saline monthly, 0.015 mg/kg ZA weekly, or 0.05 mg/kg ZA monthly. At 15 weeks DXA measurements documented that femoral head BMD was increased by 18% in ZA weekly and 21% in ZA monthly compared to controls (p < 0.01). Femoral head sphericity in animals with osteonecrosis was improved in ZA-treatment groups (p < 0.01) as measured by epiphyseal quotient (EQ). The proportion of "flat" heads (EQ ± 0.40) was significantly reduced from 32% in saline-treated animals to 12% in weekly ZA and 3% in monthly ZA (p < 0.01). Histologically there was a similar prevalence of osteonecrosis in all groups. The prevalence of ossification delay was significantly reduced by ZA treatment (p < 0.01). Zoledronic acid favorably altered femoral head shape in this spontaneous model of osteonecrosis in growing rats. Translation of these results to Perthes disease could mean that deformity of the femoral head may be modified in children, perhaps reducing the need for surgical intervention in childhood and adult life. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source]

Multi-frequency EPR and Mössbauer spectroscopic studies on freeze-quenched reaction intermediates of nitric oxide synthase ,

C. Jung
Abstract It is believed by analogy to chloroperoxidase (CPO) from Caldariomyces fumago that the electronic structure of the intermediate iron-oxo species in the catalytic cycle of nitric oxide synthase (NOS) corresponds to an iron(IV) porphyrin- , -cation radical. Such species can also be produced by the reaction of ferric NOS with external oxidants within the shunt pathway. We present multi-frequency EPR (9.6, 94, 285 GHz) and Mössbauer spectroscopic studies on freeze-quenched intermediates of the oxygenase domain of nitric oxide synthase which has reacted with peroxy acetic acid within 8,200 ms. The intermediates of the oxygenase domain of both the cytokine inducible NOS (iNOSox) and the neuronal NOS (nNOSox) show an organic radical signal in the 9.6-GHz spectrum overlapping with the spectrum of an unknown species with g -values of 2.24, 2.23 and 1.96. Using 94- and 285-GHz EPR the organic radical signal is assigned to a tyrosine radical on the basis of g -values (i.e. Tyr*562 in nNOSox and Tyr*341 in iNOSox). Mössbauer spectroscopy of 57Fe-labeled unreacted nNOSox shows a ferric low-spin heme-iron (, = 0.38 mms,1, ,EQ = 2.58 mms,1). The reaction of nNOSox with peroxy acetic acid for 8 ms leads to the disappearance of the magnetic background characteristic for native nNOSox and a new species with , = 0.27 mms,1 and ,EQ = 2.41 mms,1 is detected at 4.2 K which does not resemble the parameters typical for a Fe(IV) center. It is proposed that this intermediate species corresponds to a ferric low-spin species which magnetically couples to an amino acid radical (presumably Trp*409). Copyright © 2005 John Wiley & Sons, Ltd. [source]

The Prevalence and Impact of Chronic Pain with Neuropathic Pain Symptoms in the General Population

PAIN MEDICINE, Issue 5 2009
Cory Toth BSc, FRCPC
ABSTRACT Objective., We performed a prevalence estimate of chronic pain with neuropathic pain (NeP) symptoms to determine its frequency and associations with morbidity. Design., We conducted a telephone-based survey based upon a random sampling of both urban and rural households of the general population in one Canadian province to determine NeP prevalence and its impact upon financial well-being and quality of life. Outcome Measures., Telephonic use of the DN4 questionnaire (DN4Q), used to identify NeP symptoms in those patients with chronic pain, was validated within selected clinical populations of chronic pain. Epidemiological data was obtained for all subjects. EuroQoL (EQ)-5D data estimating quality of life was measured. Results., Chronic pain was present in 35.0% of the surveyed population of 1,207 subjects, with NeP symptoms present in 17.9%. The NeP group had significantly more pain, was female predominant, had a greater belief of being economically disadvantaged, suffered from more restrictions in mobility and in usual activities, and had overall lower EQ-5D utility scores compared with subjects with non-NeP. DN4Q validation demonstrated that pain entities not normally defined as NeP are recorded as such using the DN4Q, and that a spectrum of NeP features may occur across a host of painful conditions. Conclusion., Despite limitations of the DN4Q, symptoms of NeP may be more prevalent in the general population than expected and has a greater impact upon patients' lives than non-NeP. Limitations of the DN4Q may relate to the concept of a spectrum of NeP existent amongst heterogenous NeP and non-NeP syndromes. [source]

Effectiveness of mirtazapine for nausea and insomnia in cancer patients with depression

Sung-Wan Kim md
Aims:, The purpose of the present paper was to evaluate the effectiveness of mirtazapine orally disintegrating tablets for nausea and sleep disturbance, which are common and distressing symptoms of cancer. Methods:, This was a 4-week, prospective, open-labeled study of cancer patients. Assessments were performed at baseline and on days 1, 3, 5, 7, 14, and 28. Primary outcome measures were the Clinical Global Impression scale for nausea/vomiting and the Chonnam National University Hospital,Leeds Sleep Evaluation Questionnaire (C-LSEQ) including total amount of night sleep time. The secondary outcome measures consisted of pain items in the 36-item Short Form Health Survey, the Montgomery,Asberg Depression Rating Scale (MADRS), and the EuroQoL (EQ)-5D. Forty-two cancer patients were enrolled. Results:, Those with nausea (n = 28) improved significantly from day 1. The total night sleep time and each item on the C-LSEQ improved from days 1,5. The scores on the MADRS and the depression/anxiety dimension and visual analog scale of EQ-5D improved significantly from the first week. Pain measures also improved from day 1. Exacerbation of sleepiness developed in approximately one-third of subjects during the initial few days, but disappeared gradually. Conclusion:, In the present study mirtazapine rapidly improved nausea, sleep disturbance, pain and quality of life, as well as depression in cancer patients. Mirtazapine may be an effective treatment option in managing cancer patients with multiple distressing symptoms, including nausea and sleep disturbance. [source]

Empathy and error processing

Michael J. Larson
Abstract Recent research suggests a relationship between empathy and error processing. Error processing is an evaluative control function that can be measured using post-error response time slowing and the error-related negativity (ERN) and post-error positivity (Pe) components of the event-related potential (ERP). Thirty healthy participants completed two measures of empathy, the Interpersonal Reactivity Index (IRI) and the Empathy Quotient (EQ), and a modified Stroop task. Post-error slowing was associated with increased empathic personal distress on the IRI. ERN amplitude was related to overall empathy score on the EQ and the fantasy subscale of the IRI. The Pe and measures of empathy were not related. Results remained consistent when negative affect was controlled via partial correlation, with an additional relationship between ERN amplitude and empathic concern on the IRI. Findings support a connection between empathy and error processing mechanisms. [source]

The synthetic antioxidant, ethoxyquin, adversely affects immunity in tilapia (Oreochromis niloticus)

Abstract Ethoxyquin (EQ) has been used as an antioxidant in livestock, aquaculture and pet foods. Animal food safety law has established the upper limit of EQ in animal feed at 150 mg kg,1. However, the risk of EQ at the approved level for aquaculture feed (150 mg kg,1) to fish health is unknown. Here, we examine the effect of EQ on the immunity of tilapia (Oreochromis niloticus). EQ concentration in the blood reached 0.16 mg L,1 in fish fed EQ at the approved level. This level of EQ inhibited phagocytic activity of leucocytes in vitro and antibacterial activity of whole blood in vivo. Furthermore, pyknosis in the liver was observed throughout the duration of feeding. However, after 30 days of experimental challenge with feed containing 150 mg kg,1 of EQ, no significant difference was observed in mortality. Although EQ at the approved level in feed causes immunosuppression in fish, the severity of immunosuppression does not lead to a lowering of disease resistance for short feeding periods. [source]

Extracorporeal shock wave lithotripsy in children: equivalent clearance rates to adults is achieved with fewer and lower energy shock waves

Abraham Kurien
OBJECTIVE To compare the outcome, safety and efficiency of extracorporeal shock wave lithotripsy (ESWL) using an electromagnetic lithotripter for upper urinary tract stones in children and adults. PATIENTS AND METHODS We retrospectively reviewed data over a 5-year period for patients with solitary, renal and upper ureteric stones measuring <2 cm in whom ESWL was the treatment method. Group A consisted of 44 children (mean [sd] age 5.9 [4.4] years) and group B of 562 adults (mean [sd] age 40.9 [13.1] years). The number and energy of SWs used was not predetermined and was tailored until adequate fragmentation was achieved. Initial stone reassessment was performed at 48 h and monthly thereafter. The number of SWs, intensity of SWs, stone-free rate, auxiliary procedure rate, re-treatment rate, complication rate and effectiveness quotient (EQ) were assessed in each group. RESULTS The stone-free rate with ESWL was 84% in children and 87% in adults (P = 0.78). The EQ was 77% and 75% in children and adults, respectively (P = 0.56). The mean (sd) number of SWs and energy required per session was 950 (349) and 11.83 (0.48) kV in children and 1262 (454) and 12.36 (0.34) kV in adults (P < 0.001). The re-treatment, auxiliary procedure and complication rates were similar in both groups. CONCLUSION ESWL is as safe and effective in children as in adults for solitary renal and upper ureteric stones that are <2 cm. Children required significantly fewer and lower energy SWs to achieve equivalent results. [source]

Quasi-splitting subspaces in a pre-Hilbert space

David Buhagiar
Abstract Let S be a pre-Hilbert space. Two classes of closed subspaces of S that can naturally replace the lattice of projections in a Hilbert space are E (S) and F (S), the classes of splitting subspaces and orthogonally closed subspaces of S respectively. It is well-known that in general the algebraic structure of E (S) differs considerably from that of F (S) and the two coalesce if and only if S is a Hilbert space. In the present note we introduce the class Eq(S) of quasi-splitting subspaces of S. First it is shown that Eq(S) falls between E (S) and F (S). It is also shown that, in contrast to the other two classes, Eq(S) can sometimes be a complete lattice (without S being complete) and yet, in other examples Eq(S) is not a lattice. At the end, the algebraic structure of Eq(S) is used to characterize Hilbert spaces. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

2D internal flux compatibility equation of the flux Green element method for transient nonlinear potential problems

Akpofure E. Taigbenu
Abstract This article presents the derivation and implementation of the normal directional flux compatibility equation (relationship) at internal nodes when the Green element formulation that consistently provides accurate estimates of the primary variable, and its normal directional derivative (normal flux) is applied in 2D heterogeneous media to steady and transient potential problems. Such a relationship is required to resolve the closure problem due to having fewer integral equations than the number of unknowns at internal nodes. The derivation of the relationship is based on Stokes' theorem, which transforms the contour integral of the normal directional fluxes into a surface integral that is identically zero. The numerical discretization of the compatibility equation is demonstrated with four numerical examples using the six-node quadratic triangular and the four and eight-node rectangular elements. The incorporation of triangular elements into the current formulation demonstrates that the internal compatibility equation can be successfully implemented on irregular grids. The direct calculation of the fluxes significantly enhances the accuracy of the formulation, so that high accuracy, exceeding that of the finite element method, is achieved with very coarse spatial discretization. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Numerical simulations of the improved Boussinesq equation

Dursun Irk
Abstract In this study, numerical simulations of the improved Boussinesq equation are obtained using two finite difference schemes and two finite element methods, based on the second-and third-order time discretization. The methods are tested on the problems of propagation of a soliton and interaction of two solitons. After the L, error norm is used to measure differences between the exact and numerical solutions, the results obtained by the proposed methods are compared with recently published results. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Application of adapted homotopy perturbation method for approximate solution of Henon-Heiles system

Filiz Ta
Abstract We performed adapted homotopy perturbation method on the Henon-Heiles system with the help of the symbolic computation of package Maple 10 (User Manual by Maplesoft. www.maplesoft.com). We obtained a new approximate solution of the Henon-Heiles system. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010 [source]

An enhanced-physics-based scheme for the NS-, turbulence model

William W. Miles
Abstract We study a new enhanced-physics-based numerical scheme for the NS-alpha turbulence model that conserves both energy and helicity. Although most turbulence models (in the continuous case) conserve only energy, NS-alpha is one of only a very few that also conserve helicity. This is one reason why it is becoming accepted as the most physically accurate turbulence model. However, no numerical scheme for NS-alpha, until now, conserved both energy and helicity, and thus the advantage gained in physical accuracy by modeling with NS-alpha could be lost in a computation. This report presents a finite element numerical scheme, and gives a rigorous analysis of its conservation properties, stability, solution existence, and convergence. A key feature of the analysis is the identification of the discrete energy and energy dissipation norms, and proofs that these norms are equivalent (provided a careful choice of filtering radius) in the discrete space to the usual energy and energy dissipation norms. Numerical experiments are given to demonstrate the effectiveness of the scheme over usual (helicity-ignoring) schemes. A generalization of this scheme to a family of high-order NS-alpha-deconvolution models, which combine the attractive physical properties of NS-alpha with the high accuracy gained by combining ,-filtering with van Cittert approximate deconvolution. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

The homotopy analysis method for solving higher dimensional initial boundary value problems of variable coefficients

H. Jafari
Abstract In this article, higher dimensional initial boundary value problems of variable coefficients are solved by means of an analytic technique, namely the Homotopy analysis method (HAM). Comparisons are made between the Adomian decomposition method (ADM), the exact solution and the homotopy analysis method. The results reveal that the proposed method is very effective and simple. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Application of variational iteration method for modified Camassa-Holm and Degasperis-Procesi equations

H. Jafari
Abstract In this article, the variational iteration method (VIM) is used to obtain approximate analytical solutions of the modified Camassa-Holm and Degasperis-Procesi equations. The method is capable of reducing the size of calculation and easily overcomes the difficulty of the perturbation technique or Adomian polynomials. The results reveal that the VIM is very effective. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010 [source]

Homotopy perturbation method for numerical solutions of KdV-Burgers' and Lax's seventh-order KdV equations

Ahmet Yildirim
Abstract In this article, we applied homotopy perturbation method to obtain the solution of the Korteweg-de Vries Burgers (for short, KdVB) and Lax's seventh-order KdV (for short, LsKdV) equations. The numerical results show that homotopy perturbation method can be readily implemented to this type of nonlinear equations and excellent accuracy. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Taylor-Galerkin B-spline finite element method for the one-dimensional advection-diffusion equation

Mohan K. Kadalbajoo
Abstract The advection-diffusion equation has a long history as a benchmark for numerical methods. Taylor-Galerkin methods are used together with the type of splines known as B-splines to construct the approximation functions over the finite elements for the solution of time-dependent advection-diffusion problems. If advection dominates over diffusion, the numerical solution is difficult especially if boundary layers are to be resolved. Known test problems have been studied to demonstrate the accuracy of the method. Numerical results show the behavior of the method with emphasis on treatment of boundary conditions. Taylor-Galerkin methods have been constructed by using both linear and quadratic B-spline shape functions. Results shown by the method are found to be in good agreement with the exact solution. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

He's homotopy perturbation method for solving Korteweg-de Vries Burgers equation with initial condition

Mustafa Inc
Abstract In this article, we present the Homotopy Perturbation Method (Shortly HPM) for obtaining the numerical solutions of the Korteweg-de Vries Burgers (KdVB) equation. The series solutions are developed and the reccurance relations are given explicity. The initial approximation can be freely chosen with possibly unknown constants which can be determined by imposing the boundary and initial conditions. The results reveal that HPM is very simple and effective. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Bernstein Ritz-Galerkin method for solving an initial-boundary value problem that combines Neumann and integral condition for the wave equation

S.A. Yousefi
Abstract In this article, the Ritz-Galerkin method in Bernstein polynomial basis is implemented to give an approximate solution of a hyperbolic partial differential equation with an integral condition. We will deal here with a type of nonlocal boundary value problem, that is, the solution of a hyperbolic partial differential equation with a nonlocal boundary specification. The nonlocal conditions arise mainly when the data on the boundary cannot be measured directly. The properties of Bernstein polynomial and Ritz-Galerkin method are first presented, then Ritz-Galerkin method is used to reduce the given hyperbolic partial differential equation to the solution of algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the technique presented in this article. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Adaptive finite element approximations on nonmatching grids for second-order elliptic problems

Hongsen Chen
Abstract In this article we consider a finite element approximation for a model elliptic problem of second order on non-matching grids. This method combines the continuous finite element method with interior penalty discontinuous Galerkin method. As a special case, we develop a finite element method that is continuous on the matching part of the grid and is discontinuous on the nonmatching part. A residual type a posteriori error estimate is derived. Results of numerical experiments are presented. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

A meshless method using the radial basis functions for numerical solution of the regularized long wave equation

Ali Shokri
Abstract This article discusses on the solution of the regularized long wave (RLW) equation, which is introduced to describe the development of the undular bore, has been used for modeling in many branches of science and engineering. A numerical method is presented to solve the RLW equation. The main idea behind this numerical simulation is to use the collocation and approximating the solution by radial basis functions (RBFs). To avoid solving the nonlinear system, a predictor-corrector scheme is proposed. Several test problems are given to validate the new technique. The numerical simulation, includes the propagation of a solitary wave, interaction of two positive solitary waves, interaction of a positive and a negative solitary wave, the evaluation of Maxwellian pulse into stable solitary waves and the development of an undular bore. The three invariants of the motion are calculated to determine the conservation properties of the algorithm. The results of numerical experiments are compared with analytical solution and with those of other recently published methods to confirm the accuracy and efficiency of the presented scheme.© 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Algorithms for vector field generation in mass consistent models

Ciro Flores
Abstract Diagnostic models in meteorology are based on the fulfillment of some time independent physical constraints as, for instance, mass conservation. A successful method to generate an adjusted wind field, based on mass conservation equation, was proposed by Sasaki and leads to the solution of an elliptic problem for the multiplier. Here we study the problem of generating an adjusted wind field from given horizontal initial velocity data, by two ways. The first one is based on orthogonal projection in Hilbert spaces and leads to the same elliptic problem but with natural boundary conditions for the multiplier. We derive from this approach the so called E,algorithm. An innovative alternative proposal is obtained from a second approach where we consider the saddle,point formulation of the problem,avoiding boundary conditions for the multiplier, and solving this problem by iterative conjugate gradient methods. This leads to an algorithm that we call the CG,algorithm, which is inspired from Glowinsk's approach to solve Stokes,like problems in computational fluid dynamics. Finally, the introduction of new boundary conditions for the multiplier in the elliptic problem generates better adjusted fields than those obtained with the original boundary conditions. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 [source]

Legendre multiwavelet Galerkin method for solving the hyperbolic telegraph equation

S. A. Yousefi
Abstract Recently, it is found that telegraph equation is more suitable than ordinary diffusion equation in modeling reaction diffusion for such branches of sciences. In this article a numerical method for solving the one-dimensional hyperbolic telegraph equation is presented. The method is based upon Legendre multiwavelet approximations. The properties of Legendre multiwavelet are first presented. These properties together with Galerkin method are then utilized to reduce the telegraph equation to the solution of algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the technique. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009 [source]

Cosine expansion-based differential quadrature algorithm for numerical solution of the RLW equation

dris Da
Abstract The differential quadrature method based on cosine expansion is applied to obtain numerical solutions of the RLW equation. The propagation of single solitary wave is studied to validate the efficiency of the algorithm. Then, test problems including interaction of two and three solitary waves, undulation, and evolution of solitary waves are implemented. Solutions are compared with earlier results. Discrete conservation quantities are computed for test experiments. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009 [source]

A CFL-free explicit characteristic interior penalty scheme for linear advection-reaction equations

Kaixin Wang
Abstract We develop a CFL-free, explicit characteristic interior penalty scheme (CHIPS) for one-dimensional first-order advection-reaction equations by combining a Eulerian-Lagrangian approach with a discontinuous Galerkin framework. The CHIPS method retains the numerical advantages of the discontinuous Galerkin methods as well as characteristic methods. An optimal-order error estimate in the L2 norm for the CHIPS method is derived and numerical experiments are presented to confirm the theoretical estimates. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010 [source]