We consider the k-center problem, in which the centers are constrained to lie on two axis-parallel lines. Given a set of n weighted points in the plane, which are sorted according to their x-coordinates, we show how to test in O(n logn) time if k piercing points placed on two lines, parallel to the x-axis, can pierce all the disks of different radii centered at the n given points. This leads to...

HLP (hub location problem) tries to find locations of hub facilities and assignment of nodes to extended facilities. Hubs are facilities to collect, arrange, and distribute commodities in telecommunication networks, cargo delivery systems, etc. Hubs are very crucial and their inaccessibility impresses on network whole levels. In this paper, first, total reliability of the network is defined bas...

In this work, we study an extension of the k-center facility location problem, where centers are required to service a minimum of clients. This problem is motivated by requirements to balance the workload of centerswhile allowing each center to cater to a spread of clients.We study three variants of this problem, all of which are shown to beNP-hard. In-approximation hardness and approximation a...

In this paper, we consider a coverage problem for uncertain points in a tree. Let T be a tree containing a set P of n (weighted) demand points, and the location of each demand point Pi ∈ P is uncertain but is known to appear in one of mi points on T each associated with a probability. Given a covering range λ, the problem is to find a minimum number of points (called centers) on T to build faci...

In this paper, we consider the k-center problem for streaming points in Rd. More precisely, we consider the single-pass streaming model, where each point in the stream is allowed to be examined only once and a small amount of information can be stored in a device. Since the size of memory is much smaller than the size of the data in the streaming model, it is important to develop an algorithm w...

In this paper, a multi-objective multi-period multi-product supply chain network design problem is introduced. This problem is modeled using a multi-objective mixed integer mathematical programming. The objectives are maximizing the total profit of logistics, maximizing service level, and minimizing inconsistency of operations. Several sets of constraints are considered to handle the real situa...

We give a review of existing methods for solving the absolute and vertex restricted p-center problems on networks and propose a new integer programming formulation, a tightened version of this formulation and a new method based on successive restrictions of the new formulation. A specialization of the new method with two-element restrictions obtains the optimal p-center solution by solving a se...

In an inverse network 1-center location problem the parameters of a given network, like edge lengths or vertex weights, have to be modified at minimum total cost such that a prespecified vertex s becomes a 1-center of the network. In this paper, we consider the inverse 1-center location problem on an unweighted tree network T with n + 1 vertices in which we are allowed to increase or reduce the...

Transportation costs are a significant part of capital and operating costs of large open pit mines. Cost efficiency and high reliability of in pit crushing and conveying systems compared to conventional truck-shovel system makes it more appealing to be utilized in modern mining activities. In this paper the suitable location of an in pit crusher is investigated as a single hub location problem....