The technological model of operating area by the combined transport

The contribution deals with design technology service model using the combined transport. It assesses the performance indicators in relation to price and quality of services provided and on this basis decides on the type of the transport. This is the decision-making processes, which should answer the question, whether used directly in road freight transport, direct rail freight transport or combined transport. In this contribution is the combined transport meant as a system between the conventional modes, which are transhipped goods from road vehicles to the rail cars or river boats

THE OPTIMALIZATION OF LOCATION TRANSPORT JUNCTIONS

Tento článek je zaměřen na problematiku lokace dopravních uzlů na dopravní síti, s využitím moderních optimalizačních algoritmů. Hlavní důraz je kladen na využití genetických algoritmů, které pracují na principu umístění s jednoduchým hubem bez omezení kapacity a simulaci evolučních procesů použitých na dopravních uzlech.This article is focused on the issue of deployment of transport junctions and other transport network, using modern optimization algorithms. The main emphasis is placed on genetic algorithm operating on the principle of location with simple hub allocation without capacity constraints and simulation of evolutionary processes applied to the transport nodes

An exact solution approach based on shortest-paths for p-hub median problems

The problem of locating hub facilities arises in the design of transportation and telecommunications networks. The p-hub median problem belongs to a class of discrete location-allocation problems in which all the hubs are fully interconnected. Nonhub nodes may be either uniquely or multiply allocated to hubs. The hubs are uncapacitated and the total number of hubs, p is specified a priori. We describe a novel exact-solution approach for solving the multiple-allocation case of the p-hub median problem and show how a similar method can be adapted for solving the more difficult single-allocation case. The methods for both of these solve shortest-path problems to obtain lower bounds, which are used in a branch-and-bound scheme to obtain the exact solution. Numerical results show the superiority of this new approach over traditional LP-based methods

The hierarchical hub median problem with single assignment

Cataloged from PDF version of article.We study the problem of designing a three level hub network where the top level consists of a complete network connecting the so-called central hubs and the second and third levels are unions of star networks connecting the remaining hubs to central hubs and the demand centers to hubs and central hubs, respectively. The problem is to decide on the locations of a predetermined number of hubs and central hubs and the connections in order to minimize the total routing cost in the resulting network. This problem includes the classical p-hub median problem as a special case. We also consider a version of this problem where service quality considerations are incorporated through delivery time restrictions. We propose mixed integer programming models for these two problems and report the outcomes of a computational study using the CAB data and the Turkey data. 2009 Elsevier Ltd. All rights reserved

Location of Facility Based on Simulated Annealing and “ZKW” Algorithms

To cope with the facility location problem, a method based on simulated annealing and “ZKW” algorithm is proposed in this article. The method is applied to some real cases, which aims to deploy video content server at appropriate nodes in an undirected graph to satisfy the requirements of the consumption nodes with the least cost. Simulated annealing can easily find the optimum with less reliance on the initial solution. “ZKW” algorithm can find the shortest path and calculate the least cost from the server node to consumption node quickly. The results of three kinds of cases illustrate the efficiency of our method, which can obtain the optimum within 90 s. A comparison with Dijkstra and Floyd algorithms shows that, by using “ZKW” algorithm, the method can have large iteration with limited time. Therefore, the proposed method is able to solve this video content server location problem

Network hub locations problems: the state of the art

Cataloged from PDF version of article.Hubs are special facilities that serve as switching, transshipment and sorting points in many-to-many distribution systems. The hub location problem is concerned with locating hub facilities and allocating demand nodes to hubs in order to route the traffic between origin-destination pairs. In this paper we classify and survey network hub location models. We also include some recent trends on hub location and provide a synthesis of the literature. (C) 2007 Elsevier B.V. All rights reserved

Optimal CH-47 and C-130 Workload Balance

The Air Force can save thousands of dollars by reducing the number of blade hours on the CH-47 through finding an optimal mixture of CH-47s and C-130s to conduct current operations in Afghanistan and Iraq. Ultimately these savings will relieve maintenance operations for the CH-47 and lengthen the lifespan of the CH-47 airframe. Moreover, incorporating C-130s into the operations will reduce cargo transit time from supply depots. This study looks at the involvement of the C-130 in CH-47 airlift operations to reduce CH-47 usage and increase supply efficiency. The research focus is narrowed to current airlift operations in Afghanistan and Iraq in the CENTCOM theater of operation. A mathematical representation of current CH-47 operations augmented with C-130s is the foundation of this research. Particularly, these operations in CENTCOM\u27s area of operations are formulated as linear transportation problems using network mathematics. The uniqueness this research offers entails modified scenarios of the transportation problem solved as an optimization model. AMC requires additional constraints to be augmented with the basic transportation linear model that pushes this application in new areas. In addition, the uncommon layout of supply depots to the specified receiving airfields in Afghanistan and Iraq provide an altogether new kind of transportation problem

Spatial Analysis of Single Allocation Hub Location Problems

The final publication is available at Springer via http://dx.doi.org/10.1007/s11067-015-9311-9Hubs are special facilities that serve as switching, transshipment and sorting nodes in many-to-many distribution systems. Flow is consolidated at hubs to exploit economies of scale and to reduce transportation costs between hubs. In this article, we first identify general features of optimal hub locations for single allocation hub location problems based on only the fundamental problem data (demand for travel and spatial locations). We then exploit this knowledge to develop a straightforward heuristic methodology based on spatial proximity of nodes, dispersion and measures of node importance to delineate subsets of nodes likely to contain optimal hubs. We then develop constraints for these subsets for use in mathematical programming formulations to solve hub location problems. Our methodology can also help narrow an organization's focus to concentrate on more detailed and qualitative analyses of promising potential hub locations. Results document the value of including both demand magnitude and centrality in measuring node importance and the relevant tradeoffs in solution quality and time.Turkish Academy of Science