Mohamed Saad | Cairo University (original) (raw)
Address: Cairo, Al Qahirah, Egypt
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Papers by Mohamed Saad
Current Biology, 2003
for all of our detailed phenotypic characterizations. Measurements with scanning electron microsc... more for all of our detailed phenotypic characterizations. Measurements with scanning electron microscopy (SEM) Lily Hall 915 West State Street demonstrated that 40% (n ϭ 43) of dis1-1 stage 4 trichomes had a cell diameter of more than 30 m. In the West Lafayette, Indiana 47907-2054 wild-type, a stage 4 cell diameter exceeding 30 m was not observed in either this (n ϭ 45) or previous studies [4]
Journal of Physics-condensed Matter, 2004
Measurements on 'free-standing' single-crystal barium titanate capacitors with thicknesses down t... more Measurements on 'free-standing' single-crystal barium titanate capacitors with thicknesses down to 75 nm show a dielectric response typical of large single crystals, rather than conventional thin films. There is a notable absence of any broadening or temperature shift of the dielectric peak or loss tangent. Peak dielectric constants of ca. 25,000 are obtained, and Curie-Weiss analysis demonstrates 1 st order transformation behavior. This is in surprising contrast to results on conventionally deposited thin film capacitor heterostructures, which show large dielectric peak broadening and temperature shifts [e.g. C. B. Parker, J.-P. Maria, and A. I. Kingon, Appl. Phys. Lett. 81, 340 (2002)], as well as an apparent change in the nature of the paraelectric-ferroelectric transition from 1 st to 2 nd order. Our data are compatible with the recent model by Bratkovsky and
IEEE Journal on Selected Areas in Communications, 2004
This paper addresses the problem of routing and wavelength assignment (RWA) in multifiber WDM net... more This paper addresses the problem of routing and wavelength assignment (RWA) in multifiber WDM networks assuming neither a special topology nor wavelength converters. Given a traffic matrix, the number of fibers per link, and the number of wavelengths a fiber can support, we seek to realize the maximum number of connections. We formulate the problem as an integer linear program (ILP), and show that the selected lightpaths by this formulation can indeed be realized by properly configuring the optical switches. An upper bound on the carried traffic can be computed by solving the linear programming (LP) relaxation of the ILP formulation. However, we prove that the bound can be computed exactly by solving a significantly simplified LP, which considers only one wavelength. Consequently, our bound can easily scale to an arbitrarily large number of wavelengths. Although our formulation is path-flow based, we will demonstrate that, even if all, possibly exponentially many, paths are considered, the upper bound can always be computed in polynomial time. Our bound can thus be used as a benchmark against which exact and heuristic techniques are compared. Furthermore, we demonstrate that a simple greedy algorithm provides solutions to the original ILP formulation that are guaranteed to be within (1 − 1 e ) of its optimal solution. As the greedy algorithm considers only one wavelength at a time, it can scale to a large number of wavelengths. Computational results confirm the high efficiency of our proposed algorithm.
Current Biology, 2003
for all of our detailed phenotypic characterizations. Measurements with scanning electron microsc... more for all of our detailed phenotypic characterizations. Measurements with scanning electron microscopy (SEM) Lily Hall 915 West State Street demonstrated that 40% (n ϭ 43) of dis1-1 stage 4 trichomes had a cell diameter of more than 30 m. In the West Lafayette, Indiana 47907-2054 wild-type, a stage 4 cell diameter exceeding 30 m was not observed in either this (n ϭ 45) or previous studies [4]
Journal of Physics-condensed Matter, 2004
Measurements on 'free-standing' single-crystal barium titanate capacitors with thicknesses down t... more Measurements on 'free-standing' single-crystal barium titanate capacitors with thicknesses down to 75 nm show a dielectric response typical of large single crystals, rather than conventional thin films. There is a notable absence of any broadening or temperature shift of the dielectric peak or loss tangent. Peak dielectric constants of ca. 25,000 are obtained, and Curie-Weiss analysis demonstrates 1 st order transformation behavior. This is in surprising contrast to results on conventionally deposited thin film capacitor heterostructures, which show large dielectric peak broadening and temperature shifts [e.g. C. B. Parker, J.-P. Maria, and A. I. Kingon, Appl. Phys. Lett. 81, 340 (2002)], as well as an apparent change in the nature of the paraelectric-ferroelectric transition from 1 st to 2 nd order. Our data are compatible with the recent model by Bratkovsky and
IEEE Journal on Selected Areas in Communications, 2004
This paper addresses the problem of routing and wavelength assignment (RWA) in multifiber WDM net... more This paper addresses the problem of routing and wavelength assignment (RWA) in multifiber WDM networks assuming neither a special topology nor wavelength converters. Given a traffic matrix, the number of fibers per link, and the number of wavelengths a fiber can support, we seek to realize the maximum number of connections. We formulate the problem as an integer linear program (ILP), and show that the selected lightpaths by this formulation can indeed be realized by properly configuring the optical switches. An upper bound on the carried traffic can be computed by solving the linear programming (LP) relaxation of the ILP formulation. However, we prove that the bound can be computed exactly by solving a significantly simplified LP, which considers only one wavelength. Consequently, our bound can easily scale to an arbitrarily large number of wavelengths. Although our formulation is path-flow based, we will demonstrate that, even if all, possibly exponentially many, paths are considered, the upper bound can always be computed in polynomial time. Our bound can thus be used as a benchmark against which exact and heuristic techniques are compared. Furthermore, we demonstrate that a simple greedy algorithm provides solutions to the original ILP formulation that are guaranteed to be within (1 − 1 e ) of its optimal solution. As the greedy algorithm considers only one wavelength at a time, it can scale to a large number of wavelengths. Computational results confirm the high efficiency of our proposed algorithm.