in this paper, a two-phase algorithm, namely ivns, is proposed for solving nonlinear optimal control problems. in each phase of the algorithm, we use a variable neighborhood search (vns), which performs a uniform distribution in the shaking step and the successive quadratic programming, as the local search step. in the first phase, vns starts with a completely random initial solution of control...

In this paper we develop a variable neighborhood search (VNS) heuristic for solving mixed-integer programs (MIPs). It uses CPLEX, the general-purpose MIP solver, as a black-box. Neighborhoods around the incumbent solution are defined by adding constraints to the original problem, as suggested in the recent local branching (LB) method of Fischetti and Lodi (Mathematical Programming Series B 2003...

This paper proposes two modifications to the geometrically deformable template model. First, the optimization stage originally based on simulated annealing is replaced with a meta-heuristic called Variable Neighborhood Search that treats simulated annealing as a local search tool. Second, an affine deformation energy is introduced to improve the quality of the search. An example of optic disc s...

Dial-a-Ride problems (DARPs) arise in many urban transportation applications. The core of a DARP is a pick and delivery routing with multiple vehicles in which customers have ride-time constraints and routes have a maximum duration. This paper considers DARPs for which the objective is to minimize the routing cost, a complex optimization problem which has been studied extensively in the past. S...

The article presents a framework for the resolution of rich vehicle routing problems which are difficult to address with standard optimization techniques. We use local search on the basis on variable neighborhood search for the construction of the solutions, but embed the techniques in a flexible framework that allows the consideration of complex side constraints of the problem such as time win...

This work approaches the P-median problem with a partitioning around medoids methodology. This problem has been extensively studied because of the multiple applications and its NP-hard nature; therefore several are the efforts to find optimal solutions. In this paper we consider two case studies: 1) instances from OR-Library and 2) geographical objects from the metropolitan zone of Toluca, Mexi...

This work presents the application of Variable Neighborhood Search (VNS) based algorithms to the High School Timetabling Problem. The addressed model of the problem was proposed by the Third International Timetabling Competition (ITC 2011), which released many instances from educational institutions around the world and attracted seventeen competitors. Some of the VNS algorithm variants were ab...

We are given a set of items, each characterized by a weight and a fragility, and a large number of uncapacitated bins. Our aim is to find the minimum number of bins needed to pack all items, in such a way that in each bin the sum of the item weights is less than or equal to the smallest fragility of the items in the bin. The problem is known in the literature as the Bin Packing Problem with Fra...

On-demand transportation is becoming a new necessary service for modern (public and private) mobility and logistics providers. Large cities are demanding more and more share transportation services with flexible routes, resulting from user dynamic demands. In this study a new algorithm is proposed for solving the problem of computing the best routes that a public transportation company could of...

We consider the problem of separating two sets of points in an Euclidean space with a hyperplane that minimizes the sum of p-norm distances to the plane of points lying on the “wrong” side of the plane. A Variable Neighborhood Search metaheuristic framework is used to determine the plane coefficients. For a set of examples with L1-norm, L2-norm and L∞-norm, for which the exact solution can be c...