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41.
The objective of this paper is to study learning effects on maintenance outsourcing. We consider a situation in which a manufacturer offers a short-term outsourcing contract to an external contractor who is responsible for scheduling and performing preventive maintenance and carrying out minimal repairs when the process fails. The manufacturer’s payment to the contractor consists of a fixed amount along with cost subsidization for each maintenance operation performed. We assume learning occurs when the contractor performs preventive maintenance that reduces both time and cost. Two types of learning are considered: natural learning and learning by costly efforts. We demonstrate that a well-designed payment scheme can induce the contractor to adopt the maintenance schedule that maximizes the manufacturer’s profit. 相似文献
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H. Fu H. Yun T. K. Kwei Y. Okamoto 《Journal of polymer science. Part A, Polymer chemistry》1998,36(9):1425-1429
Two stereoisomeric poly(2-benzoyl-1,4-phenylene)s were synthesized. Polymer I has exclusively a head-to-tail structure; however, polymer II contains both head-to-head and head-to-tail units. The sulfonation reaction of polymers I and II was found to occur mainly on the meta position of the benzoyl group on the phenylene backbone. The viscosities of polymers Ia (27% sulfonated) and Ic (51% sulfonated) in aqueous solutions at 25°C were measured with and without NaBr addition. Upon the addition of NaBr (0.05 and 0.1M), the reduced viscosities were found to increase gradually and reach a constant value in each case after standing at room temperature for 30–40 h. Without NaBr, the time effect was not found. The reduced viscosities of solutions with NaBr were also higher than those without the salt. These results are quite different from the typical “polyelectrolyte” behavior. A possible explanation of the salt effect of rigid rodlike polymers such as sulfonated poly(2-benzoyl-1,4-phenylene) is discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1425–1429, 1998 相似文献
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When fast electrons cross a solid surface, surface plasmons may be generated. Surface plasmon excitations induced by electrons moving in the vacuum are generally characterized by the surface excitation parameter. This parameter was calculated for 200-1000 eV electrons crossing the surfaces of Au, Cu, Ag, Fe, Si, Ni, Pd, MgO and SiO2 with various crossing angles. Such calculations were performed based on the dielectric response theory for both incident (from vacuum to solid) and escaping (from solid to vacuum) electrons. Calculated results showed that the surface excitation parameter increased with crossing angle but decreased with electron energy. This was due to the longer time for electron-surface interaction by glancing incident or escaping electrons and by slow moving electrons. The results were fitted very well to a simple formula, i.e. , where Ps is the surface excitation parameter, E is the electron energy, α is the angle between the electron trajectory and the surface normal, and a, b and c are material dependent constants. 相似文献
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J. E. Schirber L. Hansen B. Morosin J. E. Fischer J. D. Jorgensen G. H. Kwei 《Physica C: Superconductivity and its Applications》1996,260(3-4):173-176
The pressure dependence of the superconducting transition temperature, Tc, has been determined using several gaseous pressure media and a variety of pressure-temperature cycles, both of which profoundly affect Tc. The orthorhombic “polymer” phase discussed by Zhu is found to be superconducting. Models for the unexpected behavior are discussed. 相似文献
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The Fickian diffusion coefficient of methylene chloride in a glassy epoxy polymer is calculated with the use of Crank's model of discontinuous change of D with concentration C. The diffusion constant is obtained as 1.93 × 10?6 cm2/sec. The swollen layer behind the advancing solvent front is essentially in the rubbery state of the same polymer. The case II swelling by benzene is discussed in terms of a convective transport arising from the partial stress (internal) tensor of the penetrant. The superposition of Fickian and case II diffusion found with mixtures of methylene chloride and benzene is also discussed briefly. 相似文献
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