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21.
The peeling of a d-dimensional set of points is usually performed with successive calls to a convex hull algorithm; the optimal worst-case convex hull algorithm, known to have an O(n˙ Log (n)) execution time, may give an O(n˙n˙ Log (n)) to peel all the set; an O(n˙n) convex hull algorithm, m being the number of extremal points, is shown to peel every set with an O(n-n) time, and proved to be optimal; an implementation of this algorithm is given for planar sets and spatial sets, but the latter give only an approximate O(n˙n) performance. 相似文献
22.
It is generally in a firm’s interest for its supply chain partners to invest in innovations. To the extent that these innovations either reduce the partners’ variable costs or stimulate demand for the end product, they will tend to lead to higher levels of output for all of the firms in the chain. However, in response to the innovations of its partners, a firm may have an incentive to opportunistically increase its own prices. The possibility of such opportunistic behavior creates a hold-up problem that leads supply chain partners to underinvest in innovation. Clearly, this hold-up problem could be eliminated by a pre-commitment to price. However, by making an advance commitment to price, a firm sacrifices an important means of responding to demand uncertainty. In this paper we examine the trade-off that is faced when a firm’s channel partner has opportunities to invest in either cost reduction or quality improvement, i.e. demand enhancement. Should it commit to a price in order to encourage innovation, or should it remain flexible in order to respond to demand uncertainty. We discuss several simple wholesale pricing mechanisms with respect to this trade-off. 相似文献
23.
Trees with Cantor Eigenvalue Distribution 总被引:2,自引:0,他引:2
We study a family of trees with degree k at all interior nodes and degree 1 at boundary nodes. The eigenvalues of the adjacency matrix have high multiplicities. As the trees grow, the graphs of those eigenvalues approach a piecewise-constant "Cantor function." For each value of , we will find the fraction of the eigenvalues that are given by . 相似文献
24.
Jean-Fran?ois?Cordeau Gilbert?LaporteEmail author 《4OR: A Quarterly Journal of Operations Research》2003,1(2):89-101
The Dial-a-Ride Problem (DARP) consists of designing vehicle routes and schedules for n users who specify pick-up and drop-off requests between origins and destinations. The aim is to plan a set of m minimum cost vehicle routes capable of accommodating as many users as possible, under a set of constraints. The most common example arises in door-to-door transportation for elderly or disabled people. The purpose of this article is to review the scientific literature on the DARP. The main features of the problem are described and classified and some modeling issues are discussed. A summary of the most important algorithms is provided.AMS classification:
90B06, 90C27, 90C59 相似文献
25.
A systematic method for measuring surface deformations is described which includes the use of real-time holographic interferometry, the incorporation of a carrier fringe pattern to achieve fringe linearization, and the application of image digitization and automated computer analysis for rapid quantitative interpretation. In this method, regions of interest can be selected by the use of a windowing technique in which the operator specifies the desired subregion. The problem of correctly numbering fringes which originate or vanish at the boundary where the scanning begins is solved by an algorithm which ensures correct identification of the fringe orders. The output includes a perspective plot of the out-of-plane deformation field.This method is demonstrated by its application to a measurement of the out-of-plane deformation of a hermetically sealed plastic housing loaded by internal pressurization. 相似文献
26.
27.
The core-shell structure of a range of acrylic-acrylic latexes has been investigated by combining different specimen preparation methods with transmission electron microscopy (TEM), dark-field scanning transmission electron microscopy (DSTEM) and low-voltage scanning electron microscopy (LV-SEM), including the first reported use of LV-SEM to observe composite latex particles at ambient and subambient temperatures. Spin-coating of liquid latex dispersions directly onto TEM grids or SEM stubs is shown to be a relatively straightforward mean of avoiding film formation during specimen preparation. In conjunction with double staining techniques, it has been found to be particularly convenient for characterizing the fine structure of particles with diameters down to below 100 nm. 相似文献
28.
Hyperfine Interactions - A “coherent-path” model for nuclear-resonant scattering of gamma radiation from resonant matter has been developed and is summarized here. The solution provides... 相似文献
29.
There has been much research and speculation recently on the nature of radiation induced defects in zirconium and its alloys, and in particular on the absence of voids at high fluences and temperatures in the range 0.3 to 0.5 T m (T m is the absolute melting temperature). Wolfenden and Farrell1 have reviewed the evidence and suggest that α-Zr has so far resisted void formation during neutron irradiation because of: (a) the absence of a dislocation (loop or tangle) structure and/or (b) a low insoluble gas (e.g. helium) content. 相似文献
30.
Absolute cross sections for the vibrational excitation of CO, CO2, and H2 by positron impact are presented for incident positron energies from 0.5 eV to several electron volts. The measurements use a novel technique that exploits the adiabatic motion of a positron beam in a strong magnetic field. This work is the first systematic experimental study of vibrational excitation by positron impact, and extends to energies where positron measurements have traditionally been difficult. The measured cross sections are compared with available theoretical calculations. 相似文献