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1.
Francis J. Vasko John A. McNamara Dennis D. Newhart Floyd E. Wolf 《The Journal of the Operational Research Society》1994,45(11):1285-1292
The optimum assignment of structural steel shapes to rail cars is an important logistical problem in the steel industry. In this paper, we discuss an application at Bethlehem Steel that not only involves weight and dimensional constraints, but also customer unloading constraints. The formulation is a generalized bin packing problem which is solved by modifying and extending the first fit decreasing algorithm. The solution algorithm, SOLID (for Structural Optimal Loading IDentification), has been used extensively for one of Bethlehem's high tonnage customers providing very good practical (implementable) results that achieve the desired goals. Bethlehem has enhanced this approach for use with other customers. 相似文献
2.
Dr. Jamie Hicks Dr. Petra Vasko Andreas Heilmann Prof. Jose M. Goicoechea Prof. Simon Aldridge 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20556-20560
The reactivity of the electron-rich anionic AlI aluminyl compound K2[(NON)Al]2 (NON=4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) towards mono- and disubstituted arenes is reported. C−H activation chemistry with n-butylbenzene gives exclusively the product of activation at the arene meta position. Mechanistically, this transformation proceeds in a single step via a concerted Meisenheimer-type transition state. Selectivity is therefore based on similar electronic factors to classical SNAr chemistry, which implies the destabilisation of transition states featuring electron-donating groups in either ortho or para positions. In the cases of toluene and the three isomers of xylene, benzylic C−H activation is also possible, with the product(s) formed reflecting the feasibility (or otherwise) of competing arene C−H activation at a site which is neither ortho nor para to a methyl substituent. 相似文献
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F. T. Vasko 《JETP Letters》2004,79(9):431-435
A nonstationary electron magnetotransport is studied for electrons with a partially inverted distribution formed in the passive region after an ultrashort interband photoexcitation and the emission of a cascade of optical phonons. In the case of a peaked distribution in the passive region, the conductivity is positive because of the greater contribution from the decreasing part of the distribution, while the inverted part of the distribution may give rise to a negative magnetoresistance in classical fields. If the energy of photoexcited electrons in the c zone is a multiple of the optical phonon energy, a pair of half-peaks occurs at the boundaries of the passive region. In this case, the contribution from the inverted part of the distribution (with an energy close to the phonon energy) leads to a total negative conductance and a considerable change in the magnetotransport. 相似文献
4.
F J Vasko D D Newhart K L StottJr F E Wolf 《The Journal of the Operational Research Society》2003,54(1):11-20
The traditional, uncapacitated facility location problem (UFLP) seeks to determine a set of warehouses to open such that all retail stores are serviced by a warehouse and the sum of the fixed costs of opening and operating the warehouses and the variable costs of supplying the retail stores from the opened warehouses is minimized. In this paper, we discuss the partial coverage uncapacitated facility location problem (PCUFLP) as a generalization of the uncapacitated facility location problem in which not all the retail stores must be satisfied by a warehouse. Erlenkotter's dual-ascent algorithm, DUALOC, will be used to solve optimally large (1600 stores and 13?000 candidate warehouses) real-world implemented PCUFLP applications in less than two minutes on a 500?MHz PC. Furthermore, a simple analysis of the problem input data will indicate why and when efficient solutions to large PCUFLPs can be expected. 相似文献
5.
A hot dip coating line (HDCL) is used to coat steel coils with a corrosion-resistant coating. The sequencing of the coils going into a HDCL is important to ensure that the required coating quality of each coil is achieved and that production through the facility is maximised. In this paper, the logic used in a knowledge-based sequencing system for a HDCL will be outlined. Also, how the original knowledge-based system logic was modified to include a penalty-based heuristic sequencing strategy that resulted in much-improved HDCL coil sequences will be discussed. The enhanced version of this system has been in routine use since January 1994. 相似文献
6.
An axially symmetric equilibrium model of Jupiter’s magnetodisk is developed in the MHD approximation that takes the plasma corotation and the centrifugal force into account. The model is constructed for two cases: (1) the magnetodisk plasma is assumed to have a uniform temperature; (2) the plasma pressure is assumed to be an adiabatic function of density. Analytical expressions for the magnetic field, current density, and magnetodisk temperature and thickness distributions are obtained as functions of the system parameters, viz., the radial distribution of plasma pressure in the equatorial plane, the transverse magnetic field in the center of the layer, and the angular velocity of the plasma rotation. 相似文献
7.
E. I. Vasko I. A. Melnichuk 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(5):634-637
The angular distributions of slow H ions scattered from the surface of a magnetic film with a stripe domain structure have been calculated. The calculations were performed within the models of specular and diffuse scattering upon collisions of ions with surface. It is shown that the magnetic fields of the stripe domain structure block the ions scattered at small exit angles. It is established that, within the more adequate model of diffuse scattering, the anisotropy of interaction of ions with the magnetic field of the stripe structure manifests itself in a wider angular range. 相似文献
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Francis J. Vasko Floyd E. Wolf John A. McNamara 《The Journal of the Operational Research Society》1989,40(4):361-366
Bethlehem Steel's plant at Bethlehem, Pennsylvania uses a computer-based mill-providing procedure to plan ingot requirements for the production of structural shapes and pilings. When not enough hot steel is available to meet all the ingot requirements, cold steel ingots from inventory must be substituted in order to meet the production plan. A computer system was developed that dynamically selects cold ingots to use when hot steel is not available. This system selects cold ingots based first on ingot-selection priorities, and secondly, within priorities, on several criteria. An approach was developed that assigns a penalty to each feasible cold ingot such that the priorities and multiple criteria are addressed by simply ranking the ingots based on their penalty values. Ingots are selected from the top of the ranked list, and the results are consistently acceptable to the steel-providers at the Bethlehem plant. The system improves yield and reduces material-handling costs. 相似文献