Experiments on the Node, Edge, and Arc Routing Problem

-The Node, Edge, and Arc Routing Problem (NEARP) was defined by Prins and Bouchenoua in 2004 along with the first benchmark called CBMix. The NEARP generalizes the classical Capacitated Vehicle Routing Problem (CVRP), the Capacitated Arc Routing Problem (CARP), and the General Routing Problem. It is also denoted the Mixed Capacitated General Routing Problem (MCGRP). The NEARP removes the strict and unwarranted dichotomy that previously existed in the literature between arc routing and node routing. In real applications, there are many cases where the pure node or arc routing models are not adequate. In fundamentally node-based routing applications such as newspaper delivery and communal waste management that have typically been modeled as arc routing problems in the literature, the number of points is often so large that demand aggregation is necessary. Aggregation heuristics will normally give a NEARP instance, possibly with side constraints. Hence, the NEARP is a scientifically challenging problem with high industrial relevance. In this report we present experiments with Spider, SINTEF’s industrial VRP solver, on the three NEARP benchmarks that have been published so far: CBMix, BHW, and DI-NEARP. Bach, Hasle, and Wøhlk have developed a combinatorial lower bound for the NEARP and defined the two latter benchmarks. Here, we present an experimental study with Spider on the three existing NEARP benchmarks. Upper and lower bounds are given for all instances. Three of the BHW instances have been solved to optimality. SINTEF has developed a web page for NEARP results on http://www.sintef.no/NEARP

Experiments on the Node, Edge, and Arc Routing Problem

The Node, Edge, and Arc Routing Problem (NEARP) was defined by Prins and Bouchenoua in 2004 along with the first benchmark called CBMix. The NEARP generalizes the classical Capacitated Vehicle Routing Problem (CVRP), the Capacitated Arc Routing Problem (CARP), and the General Routing Problem. It is also denoted the Mixed Capacitated General Routing Problem (MCGRP). The NEARP removes the strict and unwarranted dichotomy that previously existed in the literature between arc routing and node routing. In real applications, there are many cases where the pure node or arc routing models are not adequate. In fundamentally node-based routing applications such as newspaper delivery and communal waste management that have typically been modeled as arc routing problems in the literature, the number of points is often so large that demand aggregation is necessary. Aggregation heuristics will normally give a NEARP instance, possibly with side constraints. Hence, the NEARP is a scientifically challenging problem with high industrial relevance. In this report we present experiments with Spider, SINTEF’s industrial VRP solver, on the three NEARP benchmarks that have been published so far: CBMix, BHW, and DI-NEARP. Bach, Hasle, and Wøhlk have developed a combinatorial lower bound for the NEARP and defined the two latter benchmarks. Here, we present an experimental study with Spider on the three existing NEARP benchmarks. Upper and lower bounds are given for all instances. Three of the BHW instances have been solved to optimality. SINTEF has developed a web page for NEARP results on http://www.sintef.no/NEARP

Comparison of ultrasound vector flow imaging and CFD simulations with PIV measurements of flow in a left ventricular outflow trackt phantom - Implications for clinical use and in silico studies

In this study we have compared two modalities for flow quantification from measurement data; ultrasound (US) and shadow particle image velocimetry (PIV), and a flow simulation model using computational fluid dynamics (CFD). For the comparison we have used an idealized Quasi-2D phantom of the human left ventricular outflow tract (LVOT). The PIV data will serve as a reference for the true flow field in our setup. Furthermore, the US vector flow imaging (VFI) data has been post processed with model-based regularization developed to both smooth noise and sharpen physical flow features. The US VFI flow reconstruction results in an underestimation of the flow velocity magnitude compared to PIV and CFD. The CFD results coincide very well with the PIV flow field maximum velocities and curl intensity, as well as with the detailed vortex structure, however, this correspondence is subject to exact boundary conditions.publishedVersio

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Vehicle Routing in Media Product Distribution

We describe industrial routing problems for the design and revision of carrier routes in the newspaper and media product industry. The goal is to optimize on several criteria that are partly in conflict: number of routes, delivery costs, route balancing, route compactness, and route segregation. We discuss how these aspects may be modeled and solved. Results from computational experiments are presented. A web-based routing tool is briefly described.Vehicle Routing in Media Product Distributio

Vehicle Routing in Media Product Distribution

We describe industrial routing problems for the design and revision of carrier routes in the newspaper and media product industry. The goal is to optimize on several criteria that are partly in conflict: number of routes, delivery costs, route balancing, route compactness, and route segregation. We discuss how these aspects may be modeled and solved. Results from computational experiments are presented. A web-based routing tool is briefly described.Vehicle Routing in Media Product Distributio

Aspects of routing problems in media product distribution

Efficient construction and revision of delivery routes for newspapers and other media products is critical. We illustrate important aspects of routing problems in this industry. Typically, the goal is to optimize on several criteria that are partly in conflict: number of routes, delivery costs, route balancing, and route segregation. We describe how these aspects may be modeled and solved. Results from computational experiments on industrial cases and standard benchmarks are presented. The importance of cloud computing and parallel algorithms for modern computer architectures is described.Aspects of routing problems in media product distributio

A Capacitated Clustering-based Method for Newspaper Delivery Routing

We present an efficient solver that produces clustered, balanced, and cost effective routes for distribution in a given geographical area. Through cloud computing, the optimization functionality is used by more than 30 Nordic newspaper distribution companies for solving Large-scale Node Edge Arc Routing Problems (NEARP) with route duration, route balancing, and route compactness constraints. First, we solve a capacitated clustering problem. The corresponding NEARP solution is further optimized through a combination of Iterated Local Search, Variable Neighborhood Search, and Large Neighborhood Search.A Capacitated Clustering-based Method for Newspaper Delivery Routin

Using Heterogeneous Computing for Solving Vehicle Routing Problems

In the talk, we briefly explain modern PC architectures and the general principles of heterogeneous computing. We illustrate how multi-core and GPU computing may be utilized for higher performance and more robust VRP solvers, and explain the details of our solution method for the DVRP. We present the results of computational experiments on standard CVRP/DVRP benchmarks from the literature as well as industrial test instances from newspaper distribution. Perspectives and directions for future work are given.Using Heterogeneous Computing for Solving Vehicle Routing Problem

Vehicle Routing in Media Product Distribution

We describe industrial routing problems for the design and revision of carrier routes in the newspaper and media product industry. The goal is to optimize on several criteria that are partly in conflict: number of routes, delivery costs, route balancing, route compactness, and route segregation. We discuss how these aspects may be modeled and solved. Results from computational experiments are presented. A web-based routing tool is briefly described.Vehicle Routing in Media Product Distributio