A column generation-based heuristic for rostering with work patterns

This paper addresses the Ground Crew Rostering Problem with Work Patterns, an important manpower planning problem arising in the ground operations of airline companies. We present a cutting stock-based integer programming formulation of the problem and describe a powerful heuristic decomposition approach, which utilizes column generation and variable fixing, to construct efficient rosters for a six-month time horizon. The time horizon is divided into smaller blocks, where overlaps between the blocks ensure continuity. The proposed methodology is able to circumvent one step of the conventional roster construction process by generating rosters directly based on the estimated workload. We demonstrate that this approach has the additional advantage of being able to easily incorporate robustness in the roster. Computational results on real-life instances confirm the efficiency of the approach.     

The photoproduction of neutral pions from protons at forward angles in the resonance region

Differential cross sections for the photoproduction of pi-zero mesons from protons have been measured at angles between 10° and 70° c.m. in the energy range 0.85 GeV to 1.30 GeV. The values are compared with the fits to pion photoproduction data from three recent partial-wave analyses.     

Polarisation parameters in positive pion photoproduction

Measurements have been made of the polarisation parameters Σ, T and P for the process γp → π⁺n in the photon energy range 520–2250 MeV at c.m. angles between 30° and 120°. These data were obtained in a double polarisation experiment, using the polarised photon beam from the Daresbury electron synchrotron incident on a polarised proton target. The data are compared with predictions from current theoretical analyses.     

Some observations on the differential cross-sections for pp → K−K+

We present Legendre coefficients from fits to the differential cross-sections for $\text{p}\text{p→ K}{}^{\mathrm{?}}\text{K}{}^{\mathrm{+}}$ in the momentum range 0.8 to 2.4 GeV/c. The s-dependence of the cross-sections at small angles is examined for evidence of Reggeized baryon exchange, and a fit made to this channel and backward K⁺p elastic scattering. Comparisons are made with $\text{p}\text{p→ π}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}$.     

High transverse momentum π0 production by π− and π+ on protons at 280 GeV/c

The inclusive cross sections for π⁰ production by π^? and π⁺ on protons have been measured with a beam momentum of 280 GeV/c using a fine grained electromagnetic calorimeter and the CERN Omega spectrometer. The transverse momentum and Feynmanx _F ranges covered are 4.0<p _T <7.0 GeV/c and ?0.45<x _F <0.6 respectively. The data are compared with leading order QCD calculations.     

Chirale Erkennung bei Trisdiimin-Metallkomplexen: 3. Adsorption von Tris-(3,3′-bi-1,2,4-triazin)eisen(II)-Komplexen an Montmorillonit

Summary Adsorptionisotherms of tris-(3,3-bi-1,2,4-triazine)iron(II) complexes onto a well characterized montmorillonite are discussed in respect to the relative charge densities of adsorbent and adsorbat. While the adsorption capacities for trisbipyridyl and trisphenanthroline complexes differ for the racemates and the enantiomers they are equal for these complexes. Adsorption is limited to a monolayer. This backs the proposal that the observed chiral recognition phenomena are founded solely in the lateral interactions between adsorbats.

     

Ein sauerstoffreiches Neodymcuprat: Hochdrucksynthese und Kristallstruktur von Nd12Cu6O25 („Nd2CuO4,17”︁)

An Oxygen-rich Neodymium Cuprate: High-pressure Synthesis and Crystal Structure of Nd₁₂Cu₆O₂₅ (“Nd₂CuO_4.17”) Single crystals of Nd₁₂Cu₆O₂₅ (“Nd₂CuO_4.17”) could be obtained by reaction of Nd₂O₃ und CuO with KO₂ in a modified Belt-type apparatus at 40 kbar, 1500°C. The compound crystallizes in the monoclinic space group C2/m with a = 17.128(6), b = 3.7288(6), c = 18.364(6) Å, β = 111.22(1)º and Z = 2. The structure refinement converged at R1 = 0.0302 for 1451 reflections with F_o > 4σ(F_o) and R1 = 0.0903, wR2 = 0.0767 for all 2571 data. The structure-determining feature are Cu(1,2)? O octahedral chains, interrupted by Cu(3) atoms in square-planar coordination. Each of this CuO₄ groups is connected to another one, resulting in short copper-copper distances (d_{Cu? Cu} = 3.012 Å). A comparison of the structure of “Nd₂CuO_4.17” with those of La₂CuO₄ and Nd₂CuO₄ makes the structural relations of the former with La₂CuO₄ and, hence, the aristotype K₂NiF₄ evident, in spite of the close stoichiometric similarity between Nd₂CuO₄ and “Nd₂CuO_4.17”.