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91.
This paper is concerned with a combined production-transportation scheduling problem. The problem comprises a simple, two-machine, automated manufacturing cell, which either stands alone or is a subunit of a complete flexible manufacturing system. The cell consists of two machines in series with a dedicated part-handling device such as a crane or robotic arm for transferring parts from the first machine to the second. The loading of a new piece on the first machine and the ejection of a finished piece from the second machine are performed by dedicated automated mechanisms. The introduction of parts into the system is done n at a time, whereby the parts are reshuffled into a sequence that minimizes completion time. All processing and transfer times are considered deterministic—a reasonable assumption for a cell comprising a robotic transfer device and two CNC machining units. What complicates the problem is the assumption of a non-negligible time for the transfer device to return (empty) from the second machine to the first. The operation is a generalization of a two-machine flowshop problem, and is formulated as a specially structured, asymmetric travelling salesman problem. An approximate polynomial time 0(n log n) algorithm is proffered. The procedure incorporates a lower bound using the Gilmore–Gomory algorithm for the no-wait, two-machine flowshop problem. 相似文献
92.
Summary. In this paper, we derive a posteriori error estimates for the finite element approximation of quadratic optimal control problem
governed by linear parabolic equation. We obtain a posteriori error estimates for both the state and the control approximation.
Such estimates, which are apparently not available in the literature, are an important step towards developing reliable adaptive
finite element approximation schemes for the control problem.
Received July 7, 2000 / Revised version received January 22, 2001 / Published online January 30, 2002
RID="*"
ID="*" Supported by EPSRC research grant GR/R31980 相似文献
93.
94.
This paper investigates the existence of positive solutions of a singular boundary value problem with negative exponent similar
to standard Emden-Fowler equation. A necessary and sufficient condition for the existence of C[0, 1] positive solutions as
well as C1[0, 1] positive solutions is given by means of the method of lower and upper solutions with the Schauder fixed point theorem. 相似文献
95.
We prove that, under the assumption of the Generalized Riemann Hypothesis, the exponent of the ideal class group of a CM-field
goes to infinity with its absolute discriminant. This gives a positive answer to a question raised by Louboutin and Okazaki
[4].
Received September 10, 2001; in revised form April 5, 2002 相似文献
96.
We consider biased random walk on supercritical percolation clusters in ℤ2. We show that the random walk is transient and that there are two speed regimes: If the bias is large enough, the random
walk has speed zero, while if the bias is small enough, the speed of the random walk is positive.
Received: 20 November 2002 / Revised version: 17 January 2003
Published online: 15 April 2003
Research supported by Microsoft Research graduate fellowship.
Research partially supported by the DFG under grant SPP 1033.
Research partially supported by NSF grant #DMS-0104073 and by a Miller Professorship at UC Berkeley.
Mathematics Subject Classification (2000): 60K37; 60K35; 60G50
Key words or phrases: Percolation – Random walk 相似文献
97.
Friendly walkers is a stochastic model obtained from independent one-dimensional simple random walks {S
k
j
}
j≥0
, k=1,2,…,d by introducing ``non-crossing condition': and ``reward for collisions' characterized by parameters . Here, the reward for collisions is described as follows. If, at a given time n, a site in ℤ is occupied by exactly m≥2 walkers, then the site increases the probabilistic weight for the walkers by multiplicative factor exp (β
m
)≥1. We study the localization transition of this model in terms of the positivity of the free energy and describe the location
and the shape of the critical surface in the (d−1)-dimensional space for the parameters .
Received: 13 June 2002 / Revised version: 24 August 2002 Published online: 28 March 2003
Mathematics Subject Classification (2000): 82B41, 82B26, 82D60, 60G50
Key words or phrases: Random walks – Random surfaces – Lattice animals – Phase transitions – Polymers – Random walks 相似文献
98.
We prove Anderson localization and strong dynamical localization for random surface models in
\mathbbRd \mathbb{R}^d . 相似文献
99.
In this paper the neo-classical economic Solow-Swan model (1956) has been improved replacing its Malthusian manpower law with
the Verhulst (logistic) one. The relevant ordinary differential equation for the ratio capital/work has been then integrated
in closed form via the Hypergeometric function2
F
1. The logistic growth injection for the manpower is detected to induce a more slow dynamics onto the Solow-Swan system, which
keeps its stability. Increasing developments are displayed as the technologic progress rises. Further sceneries are tested
and the congruence of the new solution with the classical one is shown switching to zero the selflimitation coefficent in
the logistic law.
Research supported by MURST grant:Metodi matematici in economia 相似文献
100.
TangLin YangDachun 《分析论及其应用》2003,19(1):1-13
Let n≥2. In this paper, the author establishes the L^2 (R^n)-boundedness of some oscillatory singular integrals with variable rough kernels by means of some estimates on hypergeometric functions and congqucnt hypergeometric funtions. 相似文献