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

CARMA: specifications and status

The Combined Array for Research in Millimeter-wave Astronomy (CARMA) is a 23-antenna heterogeneous millimeter array under construction in the White/Inyo Mountains of eastern California. CARMA will merge the existing Owens Valley and Berkeley-Illinois-Maryland Association arrays into a single instrument focusing on pure research, technology development and student training. A new high-altitude site will enable routine 205-265 GHz observing, and may allow observations in the 345 GHz window. Eight additional 3.5-m antennas from the University of Chicago will also be integrated into CARMA when not imaging the Sunyaev-Zel'dovich effect towards clusters of galaxies. At first light, the array will observe at 12, 3 and 1.3 mm using a mix of SIS and MMIC-based receivers. A new, highly flexible correlator incorporating reprogrammable FPGA technology will process configurable subsets of the antennas specified according to the science objectives. Leading-edge water vapor radiometers will be used to correct for atmospheric opacity and signal phase fluctuations. CARMA will be capable of both high resolution and wide-field imaging, covering a range of angular scales unmatched by any current or planned millimeter-wave instrument. The high sensitivity, sub-arcsecond angular resolution and excellent uv-coverage of CARMA will ensure major advances in studies of the universe. The array will provide high-fidelity resolved images of solar-system objects, protostars, protoplanetary disks, and galaxies both nearby and at high redshift - directly addressing many key research areas in astronomy and astrophysics

Chern-Simons Theory on S^1-Bundles: Abelianisation and q-deformed Yang-Mills Theory

We study Chern-Simons theory on 3-manifolds $M$ that are circle-bundles over 2-dimensional surfaces $\Sigma$ and show that the method of Abelianisation, previously employed for trivial bundles $\Sigma \times S^1$, can be adapted to this case. This reduces the non-Abelian theory on $M$ to a 2-dimensional Abelian theory on $\Sigma$ which we identify with q-deformed Yang-Mills theory, as anticipated by Vafa et al. We compare and contrast our results with those obtained by Beasley and Witten using the method of non-Abelian localisation, and determine the surgery and framing presecription implicit in this path integral evaluation. We also comment on the extension of these methods to BF theory and other generalisations.Comment: 37 pages; v2: references adde

Linear Temperature Variation of the Penetration Depth in YBCO Thin Films

We have measured the penetration depth $\lambda(T)$ on $\rm YBa_{2}Cu_{3}O_{7}$ 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 $\lambda(T)$. In high quality films $\lambda(T)$ exhibits the same linear temperature dependence as single crystals, showing its intrinsic nature, and $\lambda(0)=1750\,{\rm \AA}$. In a lower quality one, the more usual $T^2$ dependence is found, and $\lambda(0)=3600\,{\rm \AA}$. This suggests that the $T^2$ variation is of extrinsic origin. Our results put the $d$-wave like interpretation in a much better position.Comment: 12 pages, revtex, 4 uuencoded figure

The Runaway Quiver

We point out that some recently proposed string theory realizations of dynamical supersymmetry breaking actually do not break supersymmetry in the usual desired sense. Instead, there is a runaway potential, which slides down to a supersymmetric vacuum at infinite expectation values for some fields. The runaway direction is not on a separated branch; rather, it shows up as a"tadpole" everywhere on the moduli space of field expectation values.Comment: 12 pages, no figures. v2: reference chang

Deviations from Matthiessen's Rule for SrRuO3{\rm SrRuO_3} and CaRuO3{\rm CaRuO_3}

We have measured the change in the resistivity of thin films of ${\rm SrRuO_3}$ and ${\rm CaRuO_3}$ 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

Gauge coupling flux thresholds, exotic matter and the unification scale in F-SU(5) GUT

We explore the gauge coupling relations and the unification scale in F-theory SU(5) GUT broken down to the Standard Model by an internal U(1)Y gauge flux. We consider variants with exotic matter representations which may appear in these constructions and investigate their role in the effective field theory model. We make a detailed investigation on the conditions imposed on the extraneous matter to raise the unification scale and make the color triplets heavy in order to avoid fast proton decay. We also discuss in brief the implications on the gaugino masses.Comment: 20 pages, 3 figures, references and extended comments on KK thresholds effects adde

CARMA: specifications and status

The Combined Array for Research in Millimeter-wave Astronomy (CARMA) is a 23-antenna heterogeneous millimeter array under construction in the White/Inyo Mountains of eastern California. CARMA will merge the existing Owens Valley and Berkeley-Illinois-Maryland Association arrays into a single instrument focusing on pure research, technology development and student training. A new high-altitude site will enable routine 205-265 GHz observing, and may allow observations in the 345 GHz window. Eight additional 3.5-m antennas from the University of Chicago will also be integrated into CARMA when not imaging the Sunyaev-Zel'dovich effect towards clusters of galaxies. At first light, the array will observe at 12, 3 and 1.3 mm using a mix of SIS and MMIC-based receivers. A new, highly flexible correlator incorporating reprogrammable FPGA technology will process configurable subsets of the antennas specified according to the science objectives. Leading-edge water vapor radiometers will be used to correct for atmospheric opacity and signal phase fluctuations. CARMA will be capable of both high resolution and wide-field imaging, covering a range of angular scales unmatched by any current or planned millimeter-wave instrument. The high sensitivity, sub-arcsecond angular resolution and excellent uv-coverage of CARMA will ensure major advances in studies of the universe. The array will provide high-fidelity resolved images of solar-system objects, protostars, protoplanetary disks, and galaxies both nearby and at high redshift - directly addressing many key research areas in astronomy and astrophysics