Square tubing reduces cost of telescoping bridge crane hoist

Using standard square tubing in a telescoping arrangement reduces the cost of a bridge crane hoist. Because surface tolerances of square tubing need not be as accurate as the tubing used previously and because no spline is necessary, the square tubing is significantly less expensive than splined telescoping tubes

Charged-Current Disappearance Measurements in the NuMI Off-Axis Beam

This article studies the potential of combining charged-current disappearance measurements of \nu_{\mu} to \nu_{\tau} from MINOS and an off-axis beam. I find that the error on \Delta m^2 from a 100 kt-yr off-axis measurement is a few percent of itself. Further, I find little improvement to an off-axis measurement by combining it with MINOS.Comment: Presented at NuFact'02. Four pages, three figure

Air freight demand models: An overview

A survey is presented of some of the approaches which have been considered in freight demand estimation. The few existing continuous time computer simulations of aviation systems are reviewed, with a view toward the assessment of this approach as a tool for structuring air freight studies and for relating the different components of the air freight system. The variety of available data types and sources, without which the calibration, validation and the testing of both modal split and simulation models would be impossible are also reviewed

Deployable antenna demonstration project

Test program options are described for large lightweight deployable antennas for space communications, radar and radiometry systems

MCMC with Strings and Branes: The Suburban Algorithm (Extended Version)

Motivated by the physics of strings and branes, we develop a class of Markov chain Monte Carlo (MCMC) algorithms involving extended objects. Starting from a collection of parallel Metropolis-Hastings (MH) samplers, we place them on an auxiliary grid, and couple them together via nearest neighbor interactions. This leads to a class of "suburban samplers" (i.e., spread out Metropolis). Coupling the samplers in this way modifies the mixing rate and speed of convergence for the Markov chain, and can in many cases allow a sampler to more easily overcome free energy barriers in a target distribution. We test these general theoretical considerations by performing several numerical experiments. For suburban samplers with a fluctuating grid topology, performance is strongly correlated with the average number of neighbors. Increasing the average number of neighbors above zero initially leads to an increase in performance, though there is a critical connectivity with effective dimension d_eff ~ 1, above which "groupthink" takes over, and the performance of the sampler declines.Comment: v2: 55 pages, 13 figures, references and clarifications added. Published version. This article is an extended version of "MCMC with Strings and Branes: The Suburban Algorithm

Electroweak interactions in a relativistic Fermi gas

We present a relativistic model for computing the neutrino mean free path in neutron matter. Thereby, neutron matter is described as a non-interacting Fermi gas in beta-equilibrium. We present results for the neutrino mean free path for temperatures from 0 up to 50 MeV and a broad range of neutrino energies. We show that relativistic effects cause a considerable enhancement of neutrino-scattering cross-sections in neutron matter. The influence of the $Q^2$-dependence in the electroweak form factors and the inclusion of a weak magnetic term in the hadron current is discussed. The weak-magnetic term in the hadron current is at the origin of some selective spin dependence for the nucleons which are subject to neutrino interactions.Comment: 11 pages, 7 figures, accepted to Phys. Rev. C, minor changes and updates of the figures are mad

Realizing vector meson dominance with transverse charge densities

The transverse charge density in a fast-moving nucleon is represented as a dispersion integral of the imaginary part of the Dirac form factor in the timelike region (spectral function). At a given transverse distance b the integration effectively extends over energies in a range sqrt{t} ~< 1/b, with exponential suppression of larger values. The transverse charge density at peripheral distances thus acts as a low-pass filter for the spectral function and allows one to select energy regions dominated by specific t-channel states, corresponding to definite exchange mechanisms in the spacelike form factor. We show that distances b ~ 0.5 - 1.5 fm in the isovector density are maximally sensitive to the rho meson region, with only a ~10% contribution from higher-mass states. Soft-pion exchange governed by chiral dynamics becomes relevant only at larger distances. In the isoscalar density higher-mass states beyond the omega are comparatively more important. The dispersion approach suggests that the positive transverse charge density in the neutron at b ~ 1 fm, found previously in a Fourier analysis of spacelike form factor data, could serve as a sensitive test of the the isoscalar strength in the ~1 GeV mass region. In terms of partonic structure, the transverse densities in the vector meson region b ~ 1 fm support an approximate mean-field picture of the motion of valence quarks in the nucleon.Comment: 14 pages, 12 figure