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Search Results: 1 - 10 of 953 matches for " Umar Hayat "
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A note on the canonical divisor of quasi-homogeneous affine algebraic varieties
Umar Hayat
Mathematics , 2012,
Abstract: We give a necessary and sufficient condition for the canonical divisor to vanish on a quasi-homogeneous affine algebraic variety.
The Cramer Varieties Cr(r,r+s,s)
Umar Hayat
Mathematics , 2013, DOI: 10.1016/j.geomphys.2014.02.001
Abstract: In this paper we study quasi-homogeneous affine algebraic varieties, that is, varieties obtained as closures of orbits of suitable group representations. We also discuss one interesting case that has links with the Orthogonal Grassmannian OGr(5,10). The main aim is to write the tangent bundle and the canonical class of quasi-homogeneous affine algebraic varieties in terms of group representations.
A note on the canonical divisor of the generalised affine Stiefel algebraic varieties
Umar Hayat
Mathematics , 2014,
Abstract: In this paper we study certain homogeneous spaces, which we call generalised affine Stiefel algebraic varieties. The main aim is to characterise the canonical divisor of generalised affine Stiefel algebraic varieties in terms of group representations. Affine Stiefel algebraic varieties and in particular $S^{n}$ are two special cases of the generalised affine Stiefel algebraic varieties.
Complete classification of discrete resonant Rossby/drift wave triads on periodic domains
Miguel D. Bustamante,Umar Hayat
Physics , 2012, DOI: 10.1016/j.cnsns.2012.12.024
Abstract: We consider the set of Diophantine equations that arise in the context of the barotropic vorticity equation on periodic domains, when nonlinear wave interactions are studied to leading order in the amplitudes. The solutions to this set of Diophantine equations are of interest in atmosphere (Rossby waves) and Tokamak plasmas (drift waves), because they provide the values of the spectral wavevectors that interact resonantly via three-wave interactions. These come in "triads", i.e., groups of three wavevectors. We provide the full solution to the Diophantine equations in the case of infinite Rossby deformation radius. The method is completely new, and relies on mapping the unknown variables to rational points on quadratic forms of "Minkowski" type. Classical methods invented centuries ago by Fermat, Euler, Lagrange and Minkowski, are used to classify all solutions to our original Diophantine equations, thus providing a computational method to generate numerically all the resonant triads in the system. Our method has a clear computational advantage over brute-force numerical search: on a 10000^2 grid, the brute-force search would take 15 years using optimised C++ codes, whereas our method takes about 40 minutes. The method is extended to generate quasi-resonant triads, which are defined by relaxing the resonant condition on the frequencies, allowing for a small mismatch. Quasi-resonances are robust with respect to physical perturbations, unlike exact resonances. Therefore, the new method is really valuable in practical terms. We show that the set of quasi-resonances form an intricate network of clusters of connected triads, whose structure depends on the value of the allowed mismatch. We provide some quantitative comparison between the clusters' structure and the onset of fully nonlinear turbulence in the barotropic vorticity equation, and provide perspectives for new research.
Wideband Monopole Antenna for WLAN Applications
Muhammad Umar,Nabeel Hayat Khan,Usman Ali
International Journal of Technology and Research , 2013,
Abstract: This paper presents a circular patch antenna for WLAN applications with wideband characteristics. It is shown that impedance of the antenna is matched over wideband by using the partial ground plane and quarter wave transformer with slotted TX-Line. Ansoft HFSS is used for simulation tool to map the numerical results for the return loss frequency behavior of antenna. Measure of bandwidth, return loss and radiation pattern are also reported with satisfactory performance. As the patch is circular in shape so substrate is kept in the same shape. The shape of the substrate is also discussed in details for specific antenna designs.
4-Chloro-N-[(E)-2,4-dichlorobenzylidene]aniline
Umar Hayat,Waseeq Ahmad Siddiqui,M. Nawaz Tahir,Ghulam Hussain
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810035774
Abstract: In the molecule of the title compound, C13H8Cl3N, the 4-chloroaniline and 2,4-dichlorobenzaldehyde moieties are planar with r.m.s. deviation of 0.0115 and 0.0116 , respectively, and are oriented at a dihedral angle of 13.94 (8)°.
Password Interception in a SSL/TLS Channel
Khawaja Amer Hayat,Umar Waqar Anis,Tauseef ur Rahman
Information Technology Journal , 2004,
Abstract: This study represents the attack and demonstrates the optimized form of it. It works against the latest and most popular implementations of SSL/TLS for password interception. This study showed that a password for an IMAP account can be intercepted when the eavesdropper is near the server in an hour of processing. It can be concluded that the versions of SSL/TLS are insecure when used with block ciphers in CBC mode. Before conclusion the study shows the conditions for the attack. In the end this study propose ways to make these versions strong and much more secure.
Counting of discrete Rossby/drift wave resonant triads
Miguel D. Bustamante,Umar Hayat,Peter Lynch,Brenda Quinn
Physics , 2013,
Abstract: The purpose of this note is to remove the confusion about counting of resonant wave triads for Rossby and drift waves in the context of the Charney-Hasegawa-Mima equation. In particular, we aim to point out a major error of over-counting of triads in the paper "Discrete exact and quasi-resonances of Rossby/drift waves on beta-plane with periodic boundary conditions", by Kartashov and Kartashova, arXiv:1307.8272v1 [physics.flu-dyn] (2013).
Counting of discrete Rossby/drift wave resonant triads (again)
Miguel D. Bustamante,Umar Hayat,Peter Lynch,Brenda Quinn
Physics , 2013,
Abstract: The purpose of our earlier note (arXiv:1309.0405 [physics.flu-dyn]) was to remove the confusion over counting of resonant wave triads for Rossby and drift waves in the context of the Charney-Hasegawa-Mima equation. A comment by Kartashov and Kartashova (arXiv:1309.0992v1 [physics.flu-dyn]) on that note has further confused the situation. The present note aims to remove this obfuscation.
Impact of Climate Change on Epidemiology of Various Pests of Wheat Crop in Punjab Pakistan  [PDF]
Israr Arshad, Amer Rasul, Syed Ismat Hussain, Hafiz Muhammad Usman Aslam, Khizar Hayat, Malik Najam Ul Hassan, Sidra Muqeet, ? Amina, Yasir Umar, Shabab Nasir, Anum Tehseen
American Journal of Plant Sciences (AJPS) , 2019, DOI: 10.4236/ajps.2019.101018
Abstract: Wheat [Triticum aestivum L. (Poaceae)] is the staple diet of people in Pakistan. It is attacked by many types of pests. Therefore the purpose of this study was to assess the impact of climate change on the ecology and epidemiology of various wheat pests in Punjab, Pakistan. Results indicate that maximum weeds hot spots 242 (5.98%) Phalaris minor, 45 (1.18%) wild oat and 203 (5.01%) broad leaf weeds were noted in 2015. Aphid 31 (0.86%) hot spots were recorded in 2016 while maximum army worm 13 (0.26%) hot spots were noted in 2017. Maximum 70 (1.73%) spots of yellow rust and 85 (2.10%) hot spots of brown rust were observed during 2015 while 84 (4.16%) spots of loose smut were observed during 2017. ANOVA shows that years have no significant difference (P > 0.05) but weeks have significant effect on occurrence of these pest incidences except brown rust. But regression ANOVA was significant (P ≤ 0.05) and regression models equations have been developed on the bases of recorded data. Pest incidence was taken as dependent variable Y and weather factors i.e
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