Ashraf Ali - Academia.edu (original) (raw)
Papers by Ashraf Ali
ChemInform, 1997
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Carbon nanotubes (CNT) possess many unique characteristics that promise to revolutionize the worl... more Carbon nanotubes (CNT) possess many unique characteristics that promise to revolutionize the world of structural ma- terials resulting in significant impact on our capability to build lighter, smaller and higher performance structures for aerospace and many other industrial ap- plications. When the CNT are aligned, micromechanical studies showed the po- tential of an order of magnitude increase in mechanical properties
Metallurgical and Materials Transactions A, 1996
Journal of Molecular Spectroscopy, 1989
Laser fluorescence excitation spectra and transition wavenumbers are reported for the overlapping... more Laser fluorescence excitation spectra and transition wavenumbers are reported for the overlapping B-A (8, 7) and B-X (8, 11) bands of the CN molecule. The intensities of rotational lines in these bands depend on the relative magnitude and phase of the B-A and B-X transition ...
Journal of Materials Research, 1999
Abstract Alkyl phosphates can be used as sol-gel precursors for phosphate-based glasses and glass... more Abstract Alkyl phosphates can be used as sol-gel precursors for phosphate-based glasses and glass-ceramics. An improvement in the synthesis of alkyl phosphates is presented. Following the procedure here described, it is possible to limit the fraction of condensed ...
The Journal of Chemical Physics, 1987
Relative state-to-state cross sections for rotationally inelastic collisions of N2 (B 3Pi/g/) wit... more Relative state-to-state cross sections for rotationally inelastic collisions of N2 (B 3Pi/g/) with Ar are presented. Final state populations are determined for incident levels in all three fine-structure manifolds. A pronounced preference for conservation of fine-structure label with even Delta J changes is observed for incident F1 levels. The propensity is very strong for initial J = 0 but decreases monotonically with increasing J. For incident levels in the F2 and F3 spin-orbit manifolds, fine-structure-changing collisional transitions occur with a probability essentially equal to that for fine-structure-conserving transitions. A residual even-odd alternation in the F2 final state populations is observed for incident F2 levels. These results are interpreted in terms of the quantum scattering theory for a 3Pi molecule with coupling between Hund's cases.
The Journal of Chemical Physics, 1987
An opticaloptical double resonance technique has been employed for the study of collisional tran... more An opticaloptical double resonance technique has been employed for the study of collisional transfer from the CN A Π v=8 manifold to X Σ v=12 with initial and final rotational state resolution. In contrast to our previous studies of v=3 to v=7 and v=7 to v=11 collisions, no ...
The Journal of Chemical Physics, 1986
Collisional transfer within the CN A Π v= 3 vibrational manifold and to the X Σ v= 7 manifold has... more Collisional transfer within the CN A Π v= 3 vibrational manifold and to the X Σ v= 7 manifold has been studied with initial and final rotational state resolution by an optical–optical double resonance technique. Despite the large energy gap between these two manifolds, the ...
Journal of Alloys and Compounds, 2009
The microstructure of the eutectic alloy Fe 30 Ni 20 Mn 35 Al 15 (in at.%) was modified by coolin... more The microstructure of the eutectic alloy Fe 30 Ni 20 Mn 35 Al 15 (in at.%) was modified by cooling at different rates from 1623 K, i.e., above the eutectic temperature. The lamellar spacing decreased with increasing cooling rate, and in water-quenched specimens lamellae widths of *100 nm were obtained. The orientation relationship between the fcc and B2 lamellae was found to be sensitive to the cooling rate. In a drop-cast alloy the Kurdjumov-Sachs orientation relationship dominated, whereas the orientation relationship in an arc-melted alloy with a faster cooling rate was fcc " 112 ð Þ==B2 011 ð Þ; fcc 1 " 11 ½ ==B2 1 " 11 ½ and fcc 0 " 11 ð Þ==B2 001 ð Þ; fcc 011 ½ ==B2 " 1 " 10 ½ . The hardness increased with microstructural refinement, obeying a Hall-Petch-type relationship. The strength of the alloy decreased significantly above 600 K due to softening of the B2 phase.
International Journal for Numerical Methods in Engineering, 1993
A damped system eigenvalue analysis of acoustical cavities using the boundary element method is p... more A damped system eigenvalue analysis of acoustical cavities using the boundary element method is presented.
International Journal for Numerical Methods in Engineering, 1991
Acoustic algebraic eigenvalue analysis by the Boundary Element Method (BEM) can be formulated by ... more Acoustic algebraic eigenvalue analysis by the Boundary Element Method (BEM) can be formulated by the Dual Reciprocity Method (DRM) of Nardini and Brebbia or by the Complementary Function-Particular Integral Method (PIM) proposed by Ahmad and Banerjee. But both DRM and PIM require inversion of a matrix of size at least as large as the system matrices before the equations can be cast in the form of generalized eigensystem. This makes these methods inefficient for large problems of practical interest. In this paper, a rather simple technique is proposed which eliminates the need to invert any matrix in the process of setting up the algebraic eigenvalue problem, especially for the most important case where all the boundary walls are acoustically hard (aP/an = 0). A few example problems having known analytical and experimental results are solved in order to demonstrate the validity of the new technique. It is also demonstrated that, unlike in elasticity, here the boundary element domain must be adequately zoned or an adequate number of internal points must be incorporated in order to solve truly 2-D or 3-D problems.
Computer Methods in Biomechanics and Biomedical Engineering, 2004
Experimental observations suggest that during a ligament tensile strain test, water and glycosami... more Experimental observations suggest that during a ligament tensile strain test, water and glycosaminoglycans are exuded. Many attempts have been tried to model this behaviour using continuum mechanics. We have investigated this unique behaviour and have established three mechanisms which may contribute to the experimental observations: the slackness of the fibres before stretching can lead to a decrease in volume upon straightening; a Poisson's ratio higher than 0.5 from the axial to the lateral direction (as recorded in the literature [Hewitt, J., Guilak, F., Glisson, R. and Parker Vail, T. (2001) "Regional material properties of the human hip joint capsule ligaments", Journal of Orthopaedic Research 19(3), 359-364]) due to the very high level of anisotropy of the tissue; and an osmotic pressure, with a certain level of anisotropy, that causes the swelling of the tissue before loading [Thornton, G.M., Shrive, N.G. and Frank, C.B. (2001) "Altering ligament water content affects ligament pre-stress and creep behaviour", Journal of Orthopaedic Research 19(5), 845-851]. There may be other mechanisms that also contribute in the observed fluid exudation on tensile loading.
Chemical Physics Letters, 1986
An optical-optical double resonance technique has been used to study transfer between specific qu... more An optical-optical double resonance technique has been used to study transfer between specific quantum levels in the A 2 Π and X 2 Σ 2 states of the CN radical in collisions with argon. Specific rotational levels within the v = 7 A state vibrational level are prepared by laser excitation ...
The diverse and huge volume of information available over networks makes it difficult for the use... more The diverse and huge volume of information available over networks makes it difficult for the user to find their accurate information need. Previous information retrieval system mostly uses keywords to retrieve and index the documents, which may return inaccurate result when different keywords are employed to express the same concept in the document and queries presented by the user. However, to overcome the problem of retrieving accurate information on the Web intelligently, current information retrieval approaches need to be improved. Concept-based information retrieval are playing major role in retrieving meaningful information intelligently. In this paper, we propose a novel concept-based approach using Wikipedia-based Explicit Semantic Analysis and Ontology. We propose approach that first specifies the given context of query words semantically by using Ontology, which contains Wikipedia-based concept to query words disambiguation, and then extracts corresponding concepts for each word based on the given context. As a result the retrieved documents will be more relevant to the user query and Concept-based information retrieval systems performance will improve.
ChemInform, 1997
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Carbon nanotubes (CNT) possess many unique characteristics that promise to revolutionize the worl... more Carbon nanotubes (CNT) possess many unique characteristics that promise to revolutionize the world of structural ma- terials resulting in significant impact on our capability to build lighter, smaller and higher performance structures for aerospace and many other industrial ap- plications. When the CNT are aligned, micromechanical studies showed the po- tential of an order of magnitude increase in mechanical properties
Metallurgical and Materials Transactions A, 1996
Journal of Molecular Spectroscopy, 1989
Laser fluorescence excitation spectra and transition wavenumbers are reported for the overlapping... more Laser fluorescence excitation spectra and transition wavenumbers are reported for the overlapping B-A (8, 7) and B-X (8, 11) bands of the CN molecule. The intensities of rotational lines in these bands depend on the relative magnitude and phase of the B-A and B-X transition ...
Journal of Materials Research, 1999
Abstract Alkyl phosphates can be used as sol-gel precursors for phosphate-based glasses and glass... more Abstract Alkyl phosphates can be used as sol-gel precursors for phosphate-based glasses and glass-ceramics. An improvement in the synthesis of alkyl phosphates is presented. Following the procedure here described, it is possible to limit the fraction of condensed ...
The Journal of Chemical Physics, 1987
Relative state-to-state cross sections for rotationally inelastic collisions of N2 (B 3Pi/g/) wit... more Relative state-to-state cross sections for rotationally inelastic collisions of N2 (B 3Pi/g/) with Ar are presented. Final state populations are determined for incident levels in all three fine-structure manifolds. A pronounced preference for conservation of fine-structure label with even Delta J changes is observed for incident F1 levels. The propensity is very strong for initial J = 0 but decreases monotonically with increasing J. For incident levels in the F2 and F3 spin-orbit manifolds, fine-structure-changing collisional transitions occur with a probability essentially equal to that for fine-structure-conserving transitions. A residual even-odd alternation in the F2 final state populations is observed for incident F2 levels. These results are interpreted in terms of the quantum scattering theory for a 3Pi molecule with coupling between Hund's cases.
The Journal of Chemical Physics, 1987
An opticaloptical double resonance technique has been employed for the study of collisional tran... more An opticaloptical double resonance technique has been employed for the study of collisional transfer from the CN A Π v=8 manifold to X Σ v=12 with initial and final rotational state resolution. In contrast to our previous studies of v=3 to v=7 and v=7 to v=11 collisions, no ...
The Journal of Chemical Physics, 1986
Collisional transfer within the CN A Π v= 3 vibrational manifold and to the X Σ v= 7 manifold has... more Collisional transfer within the CN A Π v= 3 vibrational manifold and to the X Σ v= 7 manifold has been studied with initial and final rotational state resolution by an optical–optical double resonance technique. Despite the large energy gap between these two manifolds, the ...
Journal of Alloys and Compounds, 2009
The microstructure of the eutectic alloy Fe 30 Ni 20 Mn 35 Al 15 (in at.%) was modified by coolin... more The microstructure of the eutectic alloy Fe 30 Ni 20 Mn 35 Al 15 (in at.%) was modified by cooling at different rates from 1623 K, i.e., above the eutectic temperature. The lamellar spacing decreased with increasing cooling rate, and in water-quenched specimens lamellae widths of *100 nm were obtained. The orientation relationship between the fcc and B2 lamellae was found to be sensitive to the cooling rate. In a drop-cast alloy the Kurdjumov-Sachs orientation relationship dominated, whereas the orientation relationship in an arc-melted alloy with a faster cooling rate was fcc " 112 ð Þ==B2 011 ð Þ; fcc 1 " 11 ½ ==B2 1 " 11 ½ and fcc 0 " 11 ð Þ==B2 001 ð Þ; fcc 011 ½ ==B2 " 1 " 10 ½ . The hardness increased with microstructural refinement, obeying a Hall-Petch-type relationship. The strength of the alloy decreased significantly above 600 K due to softening of the B2 phase.
International Journal for Numerical Methods in Engineering, 1993
A damped system eigenvalue analysis of acoustical cavities using the boundary element method is p... more A damped system eigenvalue analysis of acoustical cavities using the boundary element method is presented.
International Journal for Numerical Methods in Engineering, 1991
Acoustic algebraic eigenvalue analysis by the Boundary Element Method (BEM) can be formulated by ... more Acoustic algebraic eigenvalue analysis by the Boundary Element Method (BEM) can be formulated by the Dual Reciprocity Method (DRM) of Nardini and Brebbia or by the Complementary Function-Particular Integral Method (PIM) proposed by Ahmad and Banerjee. But both DRM and PIM require inversion of a matrix of size at least as large as the system matrices before the equations can be cast in the form of generalized eigensystem. This makes these methods inefficient for large problems of practical interest. In this paper, a rather simple technique is proposed which eliminates the need to invert any matrix in the process of setting up the algebraic eigenvalue problem, especially for the most important case where all the boundary walls are acoustically hard (aP/an = 0). A few example problems having known analytical and experimental results are solved in order to demonstrate the validity of the new technique. It is also demonstrated that, unlike in elasticity, here the boundary element domain must be adequately zoned or an adequate number of internal points must be incorporated in order to solve truly 2-D or 3-D problems.
Computer Methods in Biomechanics and Biomedical Engineering, 2004
Experimental observations suggest that during a ligament tensile strain test, water and glycosami... more Experimental observations suggest that during a ligament tensile strain test, water and glycosaminoglycans are exuded. Many attempts have been tried to model this behaviour using continuum mechanics. We have investigated this unique behaviour and have established three mechanisms which may contribute to the experimental observations: the slackness of the fibres before stretching can lead to a decrease in volume upon straightening; a Poisson's ratio higher than 0.5 from the axial to the lateral direction (as recorded in the literature [Hewitt, J., Guilak, F., Glisson, R. and Parker Vail, T. (2001) "Regional material properties of the human hip joint capsule ligaments", Journal of Orthopaedic Research 19(3), 359-364]) due to the very high level of anisotropy of the tissue; and an osmotic pressure, with a certain level of anisotropy, that causes the swelling of the tissue before loading [Thornton, G.M., Shrive, N.G. and Frank, C.B. (2001) "Altering ligament water content affects ligament pre-stress and creep behaviour", Journal of Orthopaedic Research 19(5), 845-851]. There may be other mechanisms that also contribute in the observed fluid exudation on tensile loading.
Chemical Physics Letters, 1986
An optical-optical double resonance technique has been used to study transfer between specific qu... more An optical-optical double resonance technique has been used to study transfer between specific quantum levels in the A 2 Π and X 2 Σ 2 states of the CN radical in collisions with argon. Specific rotational levels within the v = 7 A state vibrational level are prepared by laser excitation ...
The diverse and huge volume of information available over networks makes it difficult for the use... more The diverse and huge volume of information available over networks makes it difficult for the user to find their accurate information need. Previous information retrieval system mostly uses keywords to retrieve and index the documents, which may return inaccurate result when different keywords are employed to express the same concept in the document and queries presented by the user. However, to overcome the problem of retrieving accurate information on the Web intelligently, current information retrieval approaches need to be improved. Concept-based information retrieval are playing major role in retrieving meaningful information intelligently. In this paper, we propose a novel concept-based approach using Wikipedia-based Explicit Semantic Analysis and Ontology. We propose approach that first specifies the given context of query words semantically by using Ontology, which contains Wikipedia-based concept to query words disambiguation, and then extracts corresponding concepts for each word based on the given context. As a result the retrieved documents will be more relevant to the user query and Concept-based information retrieval systems performance will improve.