2,548 research outputs found
Scheduling aircraft landings - the static case
This is the publisher version of the article, obtained from the link below.In this paper, we consider the problem of scheduling aircraft (plane) landings at an airport. This problem is one of deciding a landing time for each plane such that each plane lands within a predetermined time window and that separation criteria between the landing of a plane and the landing of all successive planes are respected. We present a mixed-integer zero–one formulation of the problem for the single runway case and extend it to the multiple runway case. We strengthen the linear programming relaxations of these formulations by introducing additional constraints. Throughout, we discuss how our formulations can be used to model a number of issues (choice of objective function, precedence restrictions, restricting the number of landings in a given time period, runway workload balancing) commonly encountered in practice. The problem is solved optimally using linear programming-based tree search. We also present an effective heuristic algorithm for the problem. Computational results for both the heuristic and the optimal algorithm are presented for a number of test problems involving up to 50 planes and four runways.J.E.Beasley. would like to acknowledge the financial support of the Commonwealth Scientific and Industrial Research Organization, Australia
Generalized Konishi anomaly, Seiberg duality and singular effective superpotentials
Using the generalized Konishi anomaly (GKA) equations, we derive the
effective superpotential of four-dimensional N=1 supersymmetric SU(n) gauge
theory with n+2 fundamental flavors. We find, however, that the GKA equations
are only integrable in the Seiberg dual description of the theory, but not in
the direct description of the theory. The failure of integrability in the
direct, strongly coupled, description suggests the existence of
non-perturbative corrections to the GKA equations.Comment: 20 pages; v3: corrected the comparison to the SU(2) cas
Linear Temperature Variation of the Penetration Depth in YBCO Thin Films
We have measured the penetration depth on thin films from transmission at 120, 330 and 510~GHz,
between 5 and 50~K. Our data yield simultaneously the absolute value and the
temperature dependence of . In high quality films
exhibits the same linear temperature dependence as single crystals, showing its
intrinsic nature, and . In a lower quality one, the
more usual dependence is found, and . This
suggests that the variation is of extrinsic origin. Our results put the
-wave like interpretation in a much better position.Comment: 12 pages, revtex, 4 uuencoded figure
Embedding Fractional Quantum Hall Solitons in M-theory Compactifications
We engineer U(1)^n Chern-Simons type theories describing fractional quantum
Hall solitons (QHS) in 1+2 dimensions from M-theory compactified on eight
dimensional hyper-K\"{a}hler manifolds as target space of N=4 sigma model.
Based on M-theory/Type IIA duality, the systems can be modeled by considering
D6-branes wrapping intersecting Hirzebruch surfaces F_0's arranged as ADE
Dynkin Diagrams and interacting with higher dimensional R-R gauge fields. In
the case of finite Dynkin quivers, we recover well known values of the filling
factor observed experimentally including Laughlin, Haldane and Jain series.Comment: Latex, 14 pages. Modified version, to appear in IJGMM
Gauge Threshold Corrections for Local String Models
We study gauge threshold corrections for local brane models embedded in a
large compact space. A large bulk volume gives important contributions to the
Konishi and super-Weyl anomalies and the effective field theory analysis
implies the unification scale should be enhanced in a model-independent way
from M_s to R M_s. For local D3/D3 models this result is supported by the
explicit string computations. In this case the scale R M_s comes from the
necessity of global cancellation of RR tadpoles sourced by the local model. We
also study D3/D7 models and discuss discrepancies with the effective field
theory analysis. We comment on phenomenological implications for gauge coupling
unification and for the GUT scale.Comment: 30 pages; v2: references added, minor typos correcte
Twisted supersymmetric 5D Yang-Mills theory and contact geometry
We extend the localization calculation of the 3D Chern-Simons partition
function over Seifert manifolds to an analogous calculation in five dimensions.
We construct a twisted version of N=1 supersymmetric Yang-Mills theory defined
on a circle bundle over a four dimensional symplectic manifold. The notion of
contact geometry plays a crucial role in the construction and we suggest a
generalization of the instanton equations to five dimensional contact
manifolds. Our main result is a calculation of the full perturbative partition
function on a five sphere for the twisted supersymmetric Yang-Mills theory with
different Chern-Simons couplings. The final answer is given in terms of a
matrix model. Our construction admits generalizations to higher dimensional
contact manifolds. This work is inspired by the work of Baulieu-Losev-Nekrasov
from the mid 90's, and in a way it is covariantization of their ideas for a
contact manifold.Comment: 28 pages; v2: minor mistake corrected; v3: matches published versio
D-branes Wrapped on Fuzzy del Pezzo Surfaces
We construct classical solutions in quiver gauge theories on D0-branes
probing toric del Pezzo singularities in Calabi-Yau manifolds. Our solutions
represent D4-branes wrapped around fuzzy del Pezzo surfaces. We study the
fluctuation spectrum around the fuzzy CP^2 solution in detail. We also comment
on possible applications of our fuzzy del Pezzo surfaces to the fuzzy version
of F-theory, dubbed F(uzz) theory.Comment: 1+42 pages, 9 figures v2: references added v3: statements on the
structure of the Yukawa couplings weakened. published versio
Deviations from Matthiessen's Rule for and
We have measured the change in the resistivity of thin films of and upon introducing point defects by electron
irradiation at low temperatures, and we find significant deviations from
Matthiessen's rule. For a fixed irradiation dose, the induced change in
resistivity {\it decreases} with increasing temperature. Moreover, for a fixed
temperature, the increase in resistivity with irradiation is found to be {\it
sublinear}. We suggest that the observed behavior is due to the marked
anisotropic scattering of the electrons together with their relatively short
mean free path (both characteristic of many metallic oxides including cuprates)
which amplify effects related to the Pippard ineffectiveness condition
Emerging Non-Anomalous Baryonic Symmetries in the AdS_5/CFT_4 Correspondence
We study the breaking of baryonic symmetries in the AdS_5/CFT_4
correspondence for D3 branes at Calabi-Yau three-fold singularities. This
leads, for particular VEVs, to the emergence of non-anomalous baryonic
symmetries during the renormalization group flow. We claim that these VEVs
correspond to critical values of the B-field moduli in the dual supergravity
backgrounds. We study in detail the C^3/Z_3 orbifold, the cone over F_0 and the
C^3/Z_5 orbifold. For the first two examples, we study the dual supergravity
backgrounds that correspond to the breaking of the emerging baryonic symmetries
and identify the expected Goldstone bosons and global strings in the infra-red.
In doing so we confirm the claim that the emerging symmetries are indeed
non-anomalous baryonic symmetries.Comment: 65 pages, 15 figures;v2: minor changes, published versio
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