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1.
Rani Warsi Sullivan Mohsen Razzaghi Jutima Simsiriwong 《Mathematical Methods in the Applied Sciences》2011,34(2):140-146
The objective of this paper is to present an algorithm from which a rapidly convergent solution is obtained for Volterra integral equations of Hammerstein type. Such equations are often encountered when describing the response of viscoelastic materials where the time dependency of the material properties is often expressed in the form of a convolution integral. Frequently, singularity is encountered and often ignored when dealing with the constitutive equations of viscoelastic materials. In this paper, the singularity is incorporated in the solution and the iterative scheme used to solve the equation converges within six iterations to a typical toleration error of 10?5. The algorithm is applied to the strain response of a polymer under impulsive (constant) loading and the results show excellent correlation between the experimental and analytical solution. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
2.
Z.U.A. Warsi 《Theoretical and Computational Fluid Dynamics》1998,10(1-4):439-448
Darwin and Lighthill have studied the deformation or drift of material surfaces produced in the course of steady irrotational
flows past cylinders and spheres. This paper is devoted to a reconsideration of the same problem for axisymmetric inviscid
flows produced by arbitrary shaped bodies. Such problems cannot be solved by analytical techniques and, therefore, a recently
developed algorithm has been brought into consideration to obtain the drift function numerically. First, the case of a sphere
is considered to check and compare with the results obtained by Lighthill. Second, the developed algorithm has been used to
obtain the drift functions in chosen patches of the stream surfaces produced by a prolate ellipsoid.
Received 14 November 1996 and accepted 22 April 1997 相似文献
3.
Z. U. A. Warsi 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1977,28(3):467-479
This paper summarizes the basic theory of optimal coordinates for the three-dimensional incompressible boundary layers. Though in essence the results obtained in this paper form an extension of Kaplun's work in two dimensions, the additional considerations due to three-dimensionality have extended the scope and applicability of the theory of optimal coordinates to more complicated situations.
Résumé Cet article résume la théorie fondamentale des coordinées optimales pour les couches limites incompressibles à trois dimensions. Les résultats donnés dans cet article ne sont essentiellement que la continuation des recherches de Kaplun faites sur les couches limites à deux dimensions; mais les considérations supplémentaires dues à la tri-dimensionalité ont permis d'augmenter la portée et les applications de la théorie des coordinées optimales à des situations plus compliquées.相似文献
4.
Shahid Muhammad Nafady Ayman Shakir Imran Rana Usman Ali Sarfraz Mansoor Warsi Muhammad Farooq Hussain Rafaqat Ashiq Muhammad Naeem 《Journal of nanoparticle research》2013,15(8):1-6
Dielectric properties of porous glass nanocomposites with TGS crystals embedded into six porous matrices with average pore size from 5 to 312 nm were investigated in the temperature range from 280 to 380 K at selected frequencies. The results are discussed based on the effect of the particle size on the phase transition temperature of TGS nanocomposites. Temperature–size phase diagram of TGS composites was derived. Non-monotonic character of the temperature-driven phase transition (T p) with the decreasing particle size was determined. The nature of the T p variation can be ascribed to the size-effect theoretically predicted by Zhong et al. (Phys Rev B 50:698–703, 1994). 相似文献
5.
Usmani Zeba Mujeeb Mohd Qadir Abdul Aqil Mohd Mir Showkat Rasool Ahmad Aftab Ahmad Varish Warsi Musarrat H. Usmani Zakiya 《平面色谱法杂志一现代薄层色谱法》2020,33(6):587-597
JPC – Journal of Planar Chromatography – Modern TLC - In the present work, a simple, rapid, reliable and accessible high-performance thin-layer chromatography (HPTLC) technique has been... 相似文献
6.
In this paper an algebraic model from the constitutive equations of the subgrid stresses has been developed. This model has an additional term in comparison with the mixed model, which represents the backscatter of energy explicitly. The proposed model thus provides independent modelling of the different energy transfer mechanisms, thereby capturing the effect of subgrid scales more accurately. The model is also found to depict the flow anisotropy better than the linear and mixed models. The energy transfer capability of the model is analysed for the isotropic decay and the forced isotropic turbulence. The turbulent plane channel flow simulation is performed over three Reynolds numbers, Reτ=180, 395 and 590, and the results are compared with that of the dynamic model, Smagorinsky model, and the DNS data. Both the algebraic and dynamic models are in good agreement with the DNS data for the mean flow quantities. However, the algebraic model is found to be more accurate for the turbulence intensities and the higher‐order statistics. The capability of the algebraic model to represent backscatter is also demonstrated. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
7.
A new class of locally convex algebras, called BP*-algebras, is introduced. It is shown that this class properly includes MQ*-algebras which were introduced and studied by the first author andR. Rigelhof [10]. Among other results, it is proved that each positive functional on a BP*-algebraA is admissible but not necessarily continuous as shown by an example. However, ifA, in addition, is either (i) a Q-algebra, or (ii) has an identity and is barrelled, or (iii)A is endowed with the inductive limit topology, then each positive functional onA is continuous.This work was supported by an N.R.C. Grant. 相似文献
8.
Muhammad Nadeem Akhtar Sadia Tahir Masaaki Sadakiyo Muhammad Farooq Warsi Murad A. AlDamen You Song 《Transition Metal Chemistry》2017,42(7):635-641
A coordination polymer of formula [Cu(μ 1,3-N3)2(imH)2] n (1) has been synthesized by reaction of Cu(NO3)2 with imidazole and sodium azide in CH3OH/CH3CN. The complex was characterized by FTIR, elemental analysis, powder diffraction, thermogravimetric analysis, magnetic measurements, and single-crystal X-ray diffraction. The X-ray crystal structure shows that the Cu(II) centers have a distorted octahedral coordination geometry, being coordinated by two imidazole ligands at the trans positions. Each azide links two [Cu(imH)2]2+ units to form 1D zigzag chains. Variable-temperature magnetic susceptibility studies at low field reveal dominant intrachain ferromagnetic/antiferromagnetic interactions. Using a model with n = 10, the coupling parameters J AF = ?2.95 and J F = 17.99 with g = 2.12 have been determined. 相似文献
9.
Yulikov M Lueders P Warsi MF Chechik V Jeschke G 《Physical chemistry chemical physics : PCCP》2012,14(30):10732-10746
Nanosized gold particles were functionalised with two types of paramagnetic surface tags, one having a nitroxide radical and the other one carrying a DTPA complex loaded with Gd(3+). Selective measurements of nitroxide-nitroxide, Gd(3+)-nitroxide and Gd(3+)-Gd(3+) distances were performed on this system and information on the distance distribution in the three types of spin pairs was obtained. A numerical analysis of the dipolar frequency distributions is presented for Gd(3+) centres with moderate magnitudes of zero-field splitting, in the range of detection frequencies and resonance fields where the high-field approximation is only roughly valid. The dipolar frequency analysis confirms the applicability of DEER for distance measurements in such complexes and gives an estimate for the magnitudes of possible systematic errors due to the non-ideality of the measurement of the dipole-dipole interaction. 相似文献
10.
The factors limiting the relaxivity (r) of MRI contrast agents based on small (~2.0 nm) gold nanoparticles functionalised with paramagnetic chelates were explored using EPR spectroscopy. The EPR analysis suggested that nanoparticle-attached chelates exhibit relatively high tumbling rates which restrict their relaxivity. Two different strategies were employed in order to test this hypothesis and hence improve the relaxivity of the nanoparticle-based contrast agents. In the first approach, the particle diameter was increased. This resulted in lower surface curvature and hence tighter ligand packing, which in turn led to increased relaxivity. In the second approach, the nanoparticles were overcoated with multilayers of oppositely charged polyelectrolytes. The restricted motion of Gd(3+) chelates coated by 2-4 polymer layers led to increased relaxivity which was dramatically reduced for thicker layers, presumably due to restricted diffusion of water molecules. 相似文献