The time-dependent prize-collecting arc routing problem
DEFF Research Database (Denmark)
Black, Dan; Eglese, Richard; Wøhlk, Sanne
2013-01-01
A new problem is introduced named the Time-Dependent Prize-Collecting Arc Routing Problem (TD-PARP). It is particularly relevant to situations where a transport manager has to choose between a number of full truck load pick-ups and deliveries on a road network where travel times change with the t......A new problem is introduced named the Time-Dependent Prize-Collecting Arc Routing Problem (TD-PARP). It is particularly relevant to situations where a transport manager has to choose between a number of full truck load pick-ups and deliveries on a road network where travel times change...
An Approximation Algorithm for the Capacitated Arc Routing Problem
DEFF Research Database (Denmark)
Wøhlk, Sanne
2008-01-01
In this paper we consider approximation of the Capacitated Arc Routing Problem, which is the problem of servicing a set of edges in a graph using a fleet of capacity constrained vehicles. We present a 7/2 - 3/W-approximation algorithm for the problem and prove that this algorithm outperforms...
Capacitated arc routing problem and its extensions in waste collection
Energy Technology Data Exchange (ETDEWEB)
Fadzli, Mohammad; Najwa, Nurul [Institut Matematik Kejuruteraan, Universiti Malaysia Perlis, Kampus Pauh Putra, 02600 Arau, Perlis (Malaysia); Luis, Martino [Othman Yeop Abdullah Graduate School of Business, Universiti Utara Malaysia, 06010 Sintok, Kedah (Malaysia)
2015-05-15
Capacitated arc routing problem (CARP) is the youngest generation of graph theory that focuses on solving the edge/arc routing for optimality. Since many years, operational research devoted to CARP counterpart, known as vehicle routing problem (VRP), which does not fit to several real cases such like waste collection problem and road maintenance. In this paper, we highlighted several extensions of capacitated arc routing problem (CARP) that represents the real-life problem of vehicle operation in waste collection. By purpose, CARP is designed to find a set of routes for vehicles that satisfies all pre-setting constraints in such that all vehicles must start and end at a depot, service a set of demands on edges (or arcs) exactly once without exceeding the capacity, thus the total fleet cost is minimized. We also addressed the differentiation between CARP and VRP in waste collection. Several issues have been discussed including stochastic demands and time window problems in order to show the complexity and importance of CARP in the related industry. A mathematical model of CARP and its new version is presented by considering several factors such like delivery cost, lateness penalty and delivery time.
Capacitated arc routing problem and its extensions in waste collection
Fadzli, Mohammad; Najwa, Nurul; Luis, Martino
2015-05-01
Capacitated arc routing problem (CARP) is the youngest generation of graph theory that focuses on solving the edge/arc routing for optimality. Since many years, operational research devoted to CARP counterpart, known as vehicle routing problem (VRP), which does not fit to several real cases such like waste collection problem and road maintenance. In this paper, we highlighted several extensions of capacitated arc routing problem (CARP) that represents the real-life problem of vehicle operation in waste collection. By purpose, CARP is designed to find a set of routes for vehicles that satisfies all pre-setting constraints in such that all vehicles must start and end at a depot, service a set of demands on edges (or arcs) exactly once without exceeding the capacity, thus the total fleet cost is minimized. We also addressed the differentiation between CARP and VRP in waste collection. Several issues have been discussed including stochastic demands and time window problems in order to show the complexity and importance of CARP in the related industry. A mathematical model of CARP and its new version is presented by considering several factors such like delivery cost, lateness penalty and delivery time.
An evolutionary algorithm for the capacitated arc routing problem.
Directory of Open Access Journals (Sweden)
Dalessandro Soares Vianna
2006-08-01
Full Text Available The Capacitated Arc Routing Problem (CARP consists of visiting a subset of edges of the graph that describes the problem. CARP applications include urban waste collection and inspection of power lines. The CARP is NP-hard, even in the single-vehicle case (called Rural Postman Problem. In this case, the use of metaheuristics is an efficient solution strategy. This paper proposes a hybrid genetic algorithm for the CARP, which is tested on available instances of the literature. The results obtained until now show the effectiveness of the proposed algorithm when it is compared with lower bounds described in the literature.
Solving Arc Routing Problems Using the Lin-Kernighan-Helsgaun Algorithm
DEFF Research Database (Denmark)
Helsgaun, Keld
It is well known that many arc routing problems can be transformed into the Equality Generalized Traveling Salesman Problem (E-GTSP), which in turn can be transformed into a standard Asymmetric Traveling Salesman Problem (TSP). This opens up the possibility of solving arc routing problems using...... and general routing problem instances....
General heuristics algorithms for solving capacitated arc routing problem
Fadzli, Mohammad; Najwa, Nurul; Masran, Hafiz
2015-05-01
In this paper, we try to determine the near-optimum solution for the capacitated arc routing problem (CARP). In general, NP-hard CARP is a special graph theory specifically arises from street services such as residential waste collection and road maintenance. By purpose, the design of the CARP model and its solution techniques is to find optimum (or near-optimum) routing cost for a fleet of vehicles involved in operation. In other words, finding minimum-cost routing is compulsory in order to reduce overall operation cost that related with vehicles. In this article, we provide a combination of various heuristics algorithm to solve a real case of CARP in waste collection and benchmark instances. These heuristics work as a central engine in finding initial solutions or near-optimum in search space without violating the pre-setting constraints. The results clearly show that these heuristics algorithms could provide good initial solutions in both real-life and benchmark instances.
A lower bound for the node, edge, and arc routing problem
DEFF Research Database (Denmark)
Bach, Lukas; Hasle, Geir; Wøhlk, Sanne
2013-01-01
The Node, Edge, and Arc Routing Problem (NEARP) was defined by Prins and Bouchenoua in 2004, although similar problems have been studied before. This problem, also called the Mixed Capacitated General Routing Problem (MCGRP), generalizes the classical Capacitated Vehicle Routing Problem (CVRP......), the Capacitated Arc Routing Problem (CARP), and the General Routing Problem. It captures important aspects of real-life routing problems that were not adequately modeled in previous Vehicle Routing Problem (VRP) variants. The authors also proposed a memetic algorithm procedure and defined a set of test instances...... the CBMix benchmark. The first is based on well-known CARP instances; the second consists of real life cases of newspaper delivery routing. We provide numerical results in the form of lower and best known upper bounds for all instances of all three benchmarks. For three of the instances, the gap between...
Lower and Upper Bounds for the Node, Edge, and Arc Routing Problem
DEFF Research Database (Denmark)
Bach, Lukas; Wøhlk, Sanne; Hasle, Geir
The Node, Edge, and Arc Routing Problem (NEARP) was defined by Prins and Bouchenoua in 2004. They also proposed a memetic algorithm procedure and defined a set of test instances: the so-called CBMix benchmark. The NEARP generalizes the classical CVRP, the CARP, and the General Routing Problem...
A Branch-and-Price Algorithm for the Capacitated Arc Routing Problem with Stochastic Demands
DEFF Research Database (Denmark)
Christiansen, Christian Holk; Lysgaard, Jens; Wøhlk, Sanne
2009-01-01
We address the Capacitated Arc Routing Problem with Stochastic Demands (CARPSD), which we formulate as a Set Partitioning Problem. The CARPSD is solved by a Branch-and-Price algorithm, which we apply without graph transformation. The demand's stochastic nature is incorporated into the pricing...
A mathematical modeling proposal for a Multiple Tasks Periodic Capacitated Arc Routing Problem
Directory of Open Access Journals (Sweden)
Cleverson Gonçalves dos Santos
2015-12-01
Full Text Available The countless accidents and incidents occurred at dams at the last years, propelled the development of politics related with dams safety. One of the strategies is related to the plan for instrumentation and monitoring of dams. The monitoring demands from the technical team the reading of the auscultation data, in order to periodically monitor the dam. The monitoring plan of the dam can be modeled as a problem of mathematical program of the periodical capacitated arcs routing program (PCARP. The PCARP is considered as a generalization of the classic problem of routing in capacitated arcs (CARP due to two characteristics: 1 Planning period larger than a time unity, as that vehicle make several travels and; 2 frequency of associated visits to the arcs to be serviced over the planning horizon. For the dam's monitoring problem studied in this work, the frequent visits, along the time horizon, it is not associated to the arc, but to the instrument with which is intended to collect the data. Shows a new problem of Multiple tasks Periodic Capacitated Arc Routing Problem and its elaboration as an exact mathematical model. The new main characteristics presented are: multiple tasks to be performed on each edge or edges; different frequencies to accomplish each of the tasks; heterogeneous fleet; and flexibility for more than one vehicle passing through the same edge at the same day. The mathematical model was implemented and examples were generated randomly for the proposed model's validation.
The Time-Dependent Multiple-Vehicle Prize-Collecting Arc Routing Problem
DEFF Research Database (Denmark)
Black, Daniel; Eglese, Richard; Wøhlk, Sanne
2015-01-01
In this paper, we introduce a multi vehicle version of the Time-Dependent Prize-Collecting Arc Routing Problem (TD-MPARP). It is inspired by a situation where a transport manager has to choose between a number of full truck load pick-ups and deliveries to be performed by a fleet of vehicles. Real...
THE PERIODIC CAPACITATED ARC ROUTING PROBLEM LINEAR PROGRAMMING MODEL,METAHEURISTIC AND LOWER BOUNDS
Institute of Scientific and Technical Information of China (English)
Feng CHU; Nacima LABADI; Christian PRINS
2004-01-01
The Periodic Capacitated Arc Routing Problem (PCARP) generalizes the well known NP-hard Capacitated Arc Routing Problem (CARP) by extending the single period to multi-period horizon.The Capacitated Arc Routing Problem (CARP) is defined on an undirected network in which a fleet of identical vehicles is based at a depot node. A subset of edges, called tasks, must be serviced by a vehicle. The CARP consists of determining a set of feasible vehicle trips that minimizes the total cost of traversed edges. The PCARP involves the assignment of tasks to periods and the determination of vehicles trips in each period, to minimize the total cost on the whole horizon. This new problem arises in various real life applications such as waste collection, mail delivery, etc. In this paper, a new linear programming model and preliminary lower bounds based on graph transformation are proposed. A meta-heuristic approach - Scatter Search (SS) is developed for the PCARP and evaluated on a large variety of instances.
Implementation Weather-Type Models of Capacitated Arc Routing Problem via Heuristics
Directory of Open Access Journals (Sweden)
Zuhaimy Ismail
2011-01-01
Full Text Available Problem statement: In this study, we introduced a new and real-life condition of Capacitated Arc Routing Problem (CARP, a model that represents vehicles operation in waste collection. In general, we studied the element of rain drops that affected the collected waste weight in total by imposed a new variable namely rainy weight age. In rainy days, the household refusals did not increase in volumes, but in weights due to rain drops. Consequently, this matter thus burdened vehicles capacity and prolonged its operation time. This dynamic variable thus changes the initial CARP model where the existing model did not consider other external elements that have effected onto the model. Approach: Then we developed and enhanced CARP by integrating stochastic demand and time windows to suit the models with our specific case. Results: Objectively, CARP with stochastic demand (CARPSD and CARP with time windows (CARPTW were designed to minimize the total routing cost and number of trips for a vehicle. Our approach is to design CARP models in almost likely to road layout in residential area and graphically this model is called mesh network. We also developed a constructive heuristic that is called nearest procedure based on highest demand/cost (NPHDC and work in conjunction with switching rules to search the feasible solution. Conclusion: Our preliminary results show a higher cost and more trips are needed when the vehicle operates in rainy day compared to normal day operation.
Routing and scheduling problems
DEFF Research Database (Denmark)
Reinhardt, Line Blander
of a connection between two locations. This could be an urban bus schedule where busses are routed and this routing creates a bus schedule which the passengers between locations use. In this thesis various routing and scheduling problems will be presented. The topics covered will be routing from an origin...... set cost making the cost of the individual vehicle routes inter-dependant. Depending on the problem type, the size of the problems and time available for solving, different solution methods can be applicable. In this thesis both heuristic methods and several exact methods are investigated depending...... on the problems needed to be solved. The solution methods applied to the problems cover dynamic programming for multi constrained shortest paths, Branch-and-cut for liner shipping, Simulated annealing for transporting assisted passengers in airports, branch-cut-and-price for vehicle routing with time windows...
Major arcs for Goldbach's problem
Helfgott, H. A.
2013-01-01
The ternary Goldbach conjecture states that every odd number $n\\geq 7$ is the sum of three primes. The estimation of the Fourier series $\\sum_{p\\leq x} e(\\alpha p)$ and related sums has been central to the study of the problem since Hardy and Littlewood (1923). Here we show how to estimate such Fourier series for $\\alpha$ in the so-called major arcs, i.e., for $\\alpha$ close to a rational of small denominator. This is part of the author's proof of the ternary Goldbach conjecture. In contrast ...
Adaptive Memory Procedure to solve the Profitable Arc Tour Problem
Directory of Open Access Journals (Sweden)
Jalel Euchi
2010-05-01
Full Text Available In this paper we propose an Adaptive memory procedure to solve the Profitable Arc Tour Problem (PATP. The PATP is a variant of the well-known Vehicle Routing Problems in which a set of vehicle tours are constructed. The objective is to find a set of cycles in the vehicle tours that maximize the collection of profits minus travel costs, subject to constraints limiting the length of cycles that profit is available on arcs. Computational experiments show that our algorithms provide good results in terms of quality of solution and running times.
Minor arcs for Goldbach's problem
Helfgott, H. A.
2012-01-01
The ternary Goldbach conjecture states that every odd number n>=7 is the sum of three primes. The estimation of sums of the form \\sum_{p\\leq x} e(\\alpha p), \\alpha = a/q + O(1/q^2), has been a central part of the main approach to the conjecture since (Vinogradov, 1937). Previous work required q or x to be too large to make a proof of the conjecture for all n feasible. The present paper gives new bounds on minor arcs and the tails of major arcs. This is part of the author's proof of the ternar...
A Genetic Algorithm on Inventory Routing Problem
Directory of Open Access Journals (Sweden)
Nevin Aydın
2014-03-01
Full Text Available Inventory routing problem can be defined as forming the routes to serve to the retailers from the manufacturer, deciding on the quantity of the shipment to the retailers and deciding on the timing of the replenishments. The difference of inventory routing problems from vehicle routing problems is the consideration of the inventory positions of retailers and supplier, and making the decision accordingly. Inventory routing problems are complex in nature and they can be solved either theoretically or using a heuristics method. Metaheuristics is an emerging class of heuristics that can be applied to combinatorial optimization problems. In this paper, we provide the relationship between vendor-managed inventory and inventory routing problem. The proposed genetic for solving vehicle routing problem is described in detail.
Minor arcs for Goldbach's problem
Helfgott, H A
2012-01-01
The ternary Goldbach conjecture states that every odd number $n\\geq 7$ is the sum of three primes. The estimation of sums of the form $\\sum_{p\\leq x} e(\\alpha p)$, $\\alpha = a/q + O(1/q^2)$, has been a central part of the main approach to the conjecture since (Vinogradov, 1937). Previous work required $q$ or $x$ to be too large to make a proof of the conjecture for all $n$ feasible. The present paper gives new bounds on minor arcs and the tails of major arcs. For $q\\geq 4\\cdot 10^6$, these bounds are of the strength needed to solve the ternary Goldbach conjecture. Only the range $q\\in \\lbrack 10^5, 4\\cdot 10^6\\rbrack$ remains to be checked, possibly by brute force, before the conjecture is proven for all $n$. The new bounds are due to several qualitative improvements. In particular, this paper presents a general method for reducing the cost of Vaughan's identity, as well as a way to exploit the tails of minor arcs in the context of the large sieve.
The pyramidal capacitated vehicle routing problem
DEFF Research Database (Denmark)
Lysgaard, Jens
2010-01-01
This paper introduces the pyramidal capacitated vehicle routing problem (PCVRP) as a restricted version of the capacitated vehicle routing problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the pyramidal traveling salesman problem (PTSP). A pyramidal....... A main feature of the algorithm is that exact pricing over elementary routes are done in pseudo-polynomial time. Computational results suggest that PCVRP solutions are highly useful for obtaining near-optimal solutions to the CVRP. Furthermore, pricing of pyramidal routes may prove to be very useful...
Route Elimination Heuristic for Vehicle Routing Problem with Time Windows
Directory of Open Access Journals (Sweden)
Sándor Csiszár
2005-11-01
Full Text Available The paper deals with the design of a route elimination (RE algorithm for thevehicle routing problem with time windows (VRPTW. The problem has two objectives, oneof them is the minimal number of routes the other is the minimal cost. To cope with theseobjectives effectively two-phase solutions are often suggested in the relevant literature. Inthe first phase the main focus is the route elimination, in the second one it is the costreduction. The algorithm described here is a part of a complete VRPWT study. The methodwas developed by studying the graph behaviour during the route elimination. For thispurpose a model -called “Magic Bricks” was developed. The computation results on theSolomon problem set show that the developed algorithm is competitive with the best ones.
The Pyramidal Capacitated Vehicle Routing Problem
DEFF Research Database (Denmark)
Lysgaard, Jens
This paper introduces the Pyramidal Capacitated Vehicle Routing Problem (PCVRP) as a restricted version of the Capacitated Vehicle Routing Problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the Pyramidal Traveling Salesman Problem (PTSP). A pyramidal...... of a pyramidal route is such that its traversal can be divided in two parts, where on the first part of the route, customers are visited in nondecreasing distance from the depot, and on the remaining part of the route, customers are visited in nonincreasing distance from the depot. Such a route shape is indeed...... found in many optimal solutions to CVRP instances. An optimal solution to the PCVRP may therefore be useful in itself as a heuristic solution to the CVRP. Further, an attempt can be made to find an even better CVRP solution by solving a TSP, possibly leading to a non-pyramidal route, for each...
Vehicle routing problem in investment fund allocation
Mamat, Nur Jumaadzan Zaleha; Jaaman, Saiful Hafizah; Ahmad, Rokiah Rozita; Mohd, Ismail
2013-04-01
Since its introduction by Dantzig and Ramser in 1959, vehicle routing problem keeps evolving in theories, applications and variability. The evolution in computing and technology are also important contributors to research in solving vehicle routing problem. The main sectors of interests among researchers and practitioners for vehicle routing problem are transportation, distribution and logistics. However, literature found that concept and benefits of vehicle routing problem are not taken advantages of by researchers in the field of investment. Other methods found used in investment include multi-objective programming, linear programming, goal programming and integer programming. Yet the application of vehicle routing problem is not fully explored. A proposal on a framework of the fund allocation optimization using vehicle routing problem is presented here. Preliminary results using FTSE Bursa Malaysia data testing the framework are also given.
Rich Vehicle Routing Problems and Applications
DEFF Research Database (Denmark)
Wen, Min
of these problems was motivated by our cooperation with industrial companies, particularly Transvision A/S and its client distributors, and Danish Crown. The models and methods proposed in the thesis are general and can be applied to practical routing problems arising in many other distribution companies as well...... the company’s solution in terms of all the objectives, including the travel time, customer waiting and daily workload balances, under the given constraints considered in the work. Finally, we address an integrated vehicle routing and driver scheduling problem, in which a large number of practical constraints......The Vehicle Routing Problem (VRP) is one of the most important and challenging optimization problems in the field of Operations Research. It was introduced by Dantzig and Ramser (1959) and defined as the problem of designing the optimal set of routes for a fleet of vehicles in order to serve...
The routed inventory pooling problem
Bouma, Harmen Willem
2013-01-01
In supply chains vloeit een groot deel van de kosten voort uit voorraden en transport. Om deze reden wordt veel onderzoek gedaan naar technieken en concepten die de voorraad- en transportkosten helpen te verlagen. Twee populaire onderzoeksgebieden zijn Inventory Routing, waarbij het doel is optimale
Subset-row inequalities applied to the vehicle routing problem with time windows
DEFF Research Database (Denmark)
Jepsen, Mads Kehlet; Petersen, Bjørn; Spoorendonk, Simon;
2008-01-01
This paper presents a branch-and-cut-and-price algorithm for the vehicle-routing problem with time windows. The standard Dantzig-Wolfe decomposition of the arc flow formulation leads to a set-partitioning problem as the master problem and an elementary shortest-path problem with resource...
Genetic algorithms for the vehicle routing problem
Volna, Eva
2016-06-01
The Vehicle Routing Problem (VRP) is one of the most challenging combinatorial optimization tasks. This problem consists in designing the optimal set of routes for fleet of vehicles in order to serve a given set of customers. Evolutionary algorithms are general iterative algorithms for combinatorial optimization. These algorithms have been found to be very effective and robust in solving numerous problems from a wide range of application domains. This problem is known to be NP-hard; hence many heuristic procedures for its solution have been suggested. For such problems it is often desirable to obtain approximate solutions, so they can be found fast enough and are sufficiently accurate for the purpose. In this paper we have performed an experimental study that indicates the suitable use of genetic algorithms for the vehicle routing problem.
Integrating routing decisions in public transportation problems
Schmidt, Marie E
2014-01-01
This book treats three planning problems arising in public railway transportation planning: line planning, timetabling, and delay management, with the objective to minimize passengers’ travel time. While many optimization approaches simplify these problems by assuming that passengers’ route choice is independent of the solution, this book focuses on models which take into account that passengers will adapt their travel route to the implemented planning solution. That is, a planning solution and passengers’ routes are determined and evaluated simultaneously. This work is technically deep, with insightful findings regarding complexity and algorithmic approaches to public transportation problems with integrated passenger routing. It is intended for researchers in the fields of mathematics, computer science, or operations research, working in the field of public transportation from an optimization standpoint. It is also ideal for students who want to gain intuition and experience in doing complexity proofs ...
Fund allocation using capacitated vehicle routing problem
Mamat, Nur Jumaadzan Zaleha; Jaaman, Saiful Hafizah; Ahmad, Rokiah Rozita; Darus, Maslina
2014-09-01
In investment fund allocation, it is unwise for an investor to distribute his fund into several assets simultaneously due to economic reasons. One solution is to allocate the fund into a particular asset at a time in a sequence that will either maximize returns or minimize risks depending on the investor's objective. The vehicle routing problem (VRP) provides an avenue to this issue. VRP answers the question on how to efficiently use the available fleet of vehicles to meet a given service demand, subjected to a set of operational requirements. This paper proposes an idea of using capacitated vehicle routing problem (CVRP) to optimize investment fund allocation by employing data of selected stocks in the FTSE Bursa Malaysia. Results suggest that CRVP can be applied to solve the issue of investment fund allocation and increase the investor's profit.
Vehicle routing problem for save fuel consumption
Institute of Scientific and Technical Information of China (English)
LIU Hao; AI Wen-wen
2016-01-01
This study has extended a vehicle routing problem,by considering economy of fuel,and constructing a LF-VRP model,to obtain optimal fixed costs.Our objective was to minimize not only distance,but also the fuel consumption.A example were developed to solve the proposed models.It was found that our proposed models yielded better results than the traditional VRP models.
Directory of Open Access Journals (Sweden)
Pop Petrica
2011-01-01
Full Text Available Classical combinatorial optimization problems can be generalized in a natural way by considering a related problem relative to a given partition of the nodes of the graph into node sets. In the literature one can find generalized problems such as: generalized minimum spanning tree, generalized traveling salesman problem, generalized Steiner tree problem, generalized vehicle routing problem, etc. These generalized problems typically belong to the class of NP-complete problems; they are harder than the classical ones, and nowadays are intensively studied due to their interesting properties and applications in the real world. Because of the complexity of finding the optimal or near-optimal solution in case of the generalized combinatorial optimization problems, great effort has been made, by many researchers, to develop efficient ways of their transformation into classical corresponding variants. We present in this paper an efficient way of transforming the generalized vehicle routing problem into the vehicle routing problem, and a new integer programming formulation of the problem.
The vehicle routing problem with backhauls
Energy Technology Data Exchange (ETDEWEB)
Goetschalckx, M.; Jacobs-Blecha, C.
1989-09-05
The Vehicle Routing Problem with Backhauls is a pickup/delivery problem where on each route all deliveries must be made before any pickups. A two-phased solution methodology is proposed. In the first phase, a high quality initial feasible solution is generated based on spacefilling curves. In the second phase, this solution is improved based on optimization of the subproblems identified in a mathematical model of the problem. An extensive computational analysis of several initial solution algorithms is presented, which identifies the tradeoffs between solution quality and computational requirements. The class of greedy algorithms is capacity oriented, while K-median algorithms focus on distance. It is concluded that the greedy and K-median algorithms generate equivalent tour lengths, but that the greedy procedure reduces the required number of trucks and increases the truck utilization. The effect of exchange improvement procedures as well as optimal procedures on solution quality and run time is demonstrated. Comparisons with the Clark-Wright method adapted to backhauls are also given. 4 figs., 26 refs.
Branch and price for the time-dependent vehicle routing problem with time windows
DEFF Research Database (Denmark)
Dabia, Said; Van Woensel, Tom; De Kok, Ton;
2013-01-01
the variant of the TDVRPTW where the objective is to minimize total route duration and denote this variant the duration minimizing TDVRPTW (DM-TDVRPTW). Because of time dependency, vehicles' dispatch times at the depot are crucial as road congestion might be avoided. Because of its complexity, all known...... solution methods to the DM-TDVRPTW are based on (meta-)heuristics. The decomposition of an arc-based formulation leads to a setpartitioning problem as the master problem, and a time-dependent shortest path problem with resource constraints as the pricing problem. The master problem is solved by means...
Disruption management of the vehicle routing problem with vehicle breakdown
DEFF Research Database (Denmark)
Mu, Q; Fu, Z; Lysgaard, Jens;
2011-01-01
This paper introduces a new class of problem, the disrupted vehicle routing problem (VRP), which deals with the disruptions that occur at the execution stage of a VRP plan. The paper then focuses on one type of such problem, in which a vehicle breaks down during the delivery and a new routing...
An approximate algorithm for solving the watchman route problem
Li, Fajie; Klette, Reinhard; Sommer, G; Klette, R
2008-01-01
The watchman route problem (WRP) was first introduced in 1988 and is defined as follows: How to calculate a shortest route completely contained inside a simple polygon such that any point inside this polygon is visible from at least one point on the route? So far the best known result for the WRP is
Optimizing investment fund allocation using vehicle routing problem framework
Mamat, Nur Jumaadzan Zaleha; Jaaman, Saiful Hafizah; Ahmad, Rokiah Rozita
2014-07-01
The objective of investment is to maximize total returns or minimize total risks. To determine the optimum order of investment, vehicle routing problem method is used. The method which is widely used in the field of resource distribution shares almost similar characteristics with the problem of investment fund allocation. In this paper we describe and elucidate the concept of using vehicle routing problem framework in optimizing the allocation of investment fund. To better illustrate these similarities, sectorial data from FTSE Bursa Malaysia is used. Results show that different values of utility for risk-averse investors generate the same investment routes.
The Vehicle Routing Problem with Time Windows and Temporal Dependencies
DEFF Research Database (Denmark)
Rasmussen, Matias Sevel; Dohn, Anders Høeg; Larsen, Jesper
the schedule for each technician must respect a number of synchronization constraints with other schedules. The problem is solved using metaheuristics. Another application with synchronization between visits is in ground handling at airports. Teams drive around at the airport and are assigned tasks...... assignment and routing problem with synchronization constraints. The problem has been solved by column generation. The synchronized vehicle dispatching problem (SVDP), which is a dynamic vehicle routing problem with synchronization between vehicles. Constraint programming and local search are applied...... to be scheduled with a certain slack between them. They refer to the vehicle problem as having interdependent time windows. Temporal dependencies have been modeled for a home care routing problem in a mixed integer programming model (MIP) which was solved with a standard MIP solver. An application with general...
Exact methods for time constrained routing and related scheduling problems
DEFF Research Database (Denmark)
Kohl, Niklas
1995-01-01
a number of generalizations of the VRPTW are considered. We discuss complex routing problems with different constraints as well as important real world scheduling problems arising in transportation companies. We show how these problems can be modelled in the same framework as the VRPTW. This means......This dissertation presents a number of optimization methods for the Vehicle Routing Problem with Time Windows (VRPTW). The VRPTW is a generalization of the well known capacity constrained Vehicle Routing Problem (VRP), where a fleet of vehicles based at a central depot must service a set...... of J?rnsten, Madsen and S?rensen (1986), which has been tested computationally by Halse (1992). Both methods decompose the problem into a series of time and capacity constrained shotest path problems. This yields a tight lower bound on the optimal objective, and the dual gap can often be closed...
Tawanda’s non- iterative optimal tree algorithm for shortest route problems
Directory of Open Access Journals (Sweden)
Trust Tawanda
2013-03-01
Full Text Available So many algorithms have been proposed to solve the shortest path in road networks, in this paper, an algorithm is developed to solve shortest route problems. The algorithm is being demonstrated through solving of various network problems. The principle of the algorithm consist in transforming the graph into a tree by means of arc and node replication, thereby expanding outwards from the source node considering all possible paths up to the destination node. The objective is to develop a method that can be applied in directed and non-directed graphs.
Multicast Routing Problem Using Tree-Based Cuckoo Optimization Algorithm
Directory of Open Access Journals (Sweden)
Mahmood Sardarpour
2016-06-01
Full Text Available The problem of QoS multicast routing is to find a multicast tree with the least expense/cost which would meet the limitations such as band width, delay and loss rate. This is a NP-Complete problem. To solve the problem of multicast routing, the entire routes from the source node to every destination node are often recognized. Then the routes are integrated and changed into a single multicast tree. But they are slow and complicated methods. The present paper introduces a new tree-based optimization method to overcome such weaknesses. The recommended method directly optimizes the multicast tree. Therefore a tree-based typology including several spanning trees is created which combines the trees two by two. For this purpose, the Cuckoo Algorithm is used which is proved to be well converged and makes quick calculations. The simulation conducted on different types of network typologies proved that it is a practical and influential algorithm.
Robustness of a routing tree for the Push Tree Problem
Havet, Frédéric
2002-01-01
The Push Tree problem contains elements from both the Steiner Tree and Shortest Path problem. It deals with the trade-offs between the push and pull mechanism used in information distribution and retrieval. In , a two step approach for the Push Tree Problem was proposed. In the first step, a «good» spanning tree (called routing tree) is constructed and then the problem is solved in this particular tree. Finding a routing tree is NP-hard but the second step may be performed easily, thus the id...
An Effective Hybrid Optimization Algorithm for Capacitated Vehicle Routing Problem
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Capacitated vehicle routing problem (CVRP) is an important combinatorial optimization problem. However, it is quite difficult to achieve an optimal solution with the traditional optimization methods owing to the high computational complexity. A hybrid algorithm was developed to solve the problem, in which an artificial immune clonal algorithm (AICA) makes use of the global search ability to search the optimal results and simulated annealing (SA) algorithm employs certain probability to avoid becoming trapped in a local optimum. The results obtained from the computational study show that the proposed algorithm is a feasible and effective method for capacitated vehicle routing problem.
The Service-Time Restricted Capacitated Arc Routing Problem
DEFF Research Database (Denmark)
Lystlund, Lise; Wøhlk, Sanne
We consider an inventory system, operated by a base stock policy and serving two customer classes. One customer class, Class 1, does not provide any advance demand information at all, while the other, Class 2, does. In order to reward a customer of Class 2 for providing advance order information...
Ant Colony Algorithm for Solving QoS Routing Problem
Institute of Scientific and Technical Information of China (English)
SUN Li-juan; WANG Liang-jun; WANG Ru-chuan
2004-01-01
Based on the state transition rule, the local updating rule and the global updating rule of ant colony algorithm, we propose an improved ant colony algorithm of the least-cost quality of service (QoS) unicast routing. The algorithm is used for solving the routing problem with delay, delay jitter, bandwidth, and packet loss-constrained. In the simulation, about 52.33% ants find the successful QoS routing , and converge to the best. It is proved that the algorithm is efficient and effective.
A Subpath Ejection Method for the Vehicle Routing Problem
César Rego
1998-01-01
Generically, ejection chains are methods conceived to allow solution transformations to be efficiently carried out by modifying a variable number of their components at each step of a local search algorithm. We consider a subpath ejection chain method for the vehicle routing problem (VRP) under capacity and route length restrictions. The method undertakes the identification of a substructure named the flower reference structure which, besides coordinating moves during an ejection chain constr...
Dispersal routes reconstruction and the minimum cost arborescence problem.
Hordijk, Wim; Broennimann, Olivier
2012-09-01
We show that the dispersal routes reconstruction problem can be stated as an instance of a graph theoretical problem known as the minimum cost arborescence problem, for which there exist efficient algorithms. Furthermore, we derive some theoretical results, in a simplified setting, on the possible optimal values that can be obtained for this problem. With this, we place the dispersal routes reconstruction problem on solid theoretical grounds, establishing it as a tractable problem that also lends itself to formal mathematical and computational analysis. Finally, we present an insightful example of how this framework can be applied to real data. We propose that our computational method can be used to define the most parsimonious dispersal (or invasion) scenarios, which can then be tested using complementary methods such as genetic analysis.
The vehicle routing problem with time windows and temporal dependencies
DEFF Research Database (Denmark)
Dohn, Anders Høeg; Rasmussen, Matias Sevel; Larsen, Jesper
2011-01-01
In this article, we formulate the vehicle routing problem with time windows and temporal dependencies. The problem is an extension of the well studied vehicle routing problem with time windows. In addition to the usual constraints, a scheduled time of one visit may restrain the scheduling options...... on the relaxed master problems. Finally, a computational study is performed to quantitatively reveal strengths and weaknesses of the proposed formulations. It is concluded that, depending on the problem at hand, the best performance is achieved either by relaxing the generalized precedence constraints...... in the master problem, or by using a time‐indexed model, where generalized precedence constraints are added as cuts when they become severely violated. © 2011 Wiley Periodicals, Inc. NETWORKS, Vol. 58(4), 273–289 2011...
Genetic Algorithm for Biobjective Urban Transit Routing Problem
Directory of Open Access Journals (Sweden)
J. S. C. Chew
2013-01-01
Full Text Available This paper considers solving a biobjective urban transit routing problem with a genetic algorithm approach. The objectives are to minimize the passengers’ and operators’ costs where the quality of the route sets is evaluated by a set of parameters. The proposed algorithm employs an adding-node procedure which helps in converting an infeasible solution to a feasible solution. A simple yet effective route crossover operator is proposed by utilizing a set of feasibility criteria to reduce the possibility of producing an infeasible network. The computational results from Mandl’s benchmark problems are compared with other published results in the literature and the computational experiments show that the proposed algorithm performs better than the previous best published results in most cases.
Meta Heuristic Algorithms for Vehicle Routing Problem with Stochastic Demands
Directory of Open Access Journals (Sweden)
Geetha Shanmugam
2011-01-01
Full Text Available Problem statement: The shipment of goods from manufacturer to the consumer is a focal point of distribution logistics. In reality, the demand of consumers is not known a priori. This kind of distribution is dealt by Stochastic Vehicle Routing Problem (SVRP which is a NP-hard problem. In this proposed work, VRP with stochastic demand is considered. A probability distribution is considered as a random variable for stochastic demand of a customer. Approach: In this study, VRPSD is resolved using Meta heuristic algorithms such as Genetic Algorithm (GA, Particle Swarm Optimization (PSO and Hybrid PSO (HPSO. Dynamic Programming (DP is used to find the expected cost of each route generated by GA, PSO and HPSO. Results: The objective is to minimize the total expected cost of a priori route. The fitness value of a priori route is calculated using DP. In proposed HPSO, the initial particles are generated based Nearest Neighbor Heuristic (NNH. Elitism is used in HPSO for updating the particles. The algorithm is implemented using MATLAB7.0 and tested with problems having different number of customers. The results obtained are competitive in terms of execution time and memory usage. Conclusion: The computational time is reduced as polynomial time as O(nKQ time and the memory required is O(nQ. The ANOVA test is performed to compare the proposed HPSO with other heuristic algorithms.
Considering lost sale in inventory routing problems for perishable goods
DEFF Research Database (Denmark)
Mirzaei, Samira; Seifi, Abbas
2015-01-01
This paper presents a mathematical model for an inventory routing problem (IRP). The model is especially designed for allocating the stock of perishable goods. It is assumed that the age of the perishable inventory has a negative impact on the demand of end customers and a percentage of the deman...
Genetic Algorithm for Vehicle Routing Problem with Backhauls
Directory of Open Access Journals (Sweden)
W.Nurfahizul Ifwah. WA
2012-07-01
Full Text Available The Vehicle Routing Problem with Backhauls (VRPB is an extension of the classical Vehicle Routing Problem (VRP that includes both a set of customers to whom products are to be delivered and a set of suppliers whose goods need to be transported back to the distribution center. In addition, on each route all deliveries have to be made before any goods can be picked up to avoid rearranging the loads on the vehicle. The main objective for VRPB is to determine the network route to minimize the total cost, distance or time. There are a few methods that can be identified to solve this VRPB. The objective of this research is to present a heuristic method, called Genetic Algorithm (GA, for the VRPB. In brief, GA is a system developing methods that use the natural principle of a genetic population and involved three main processes that is crossover, mutation and inversion. GA implementation on the 68 nodes problems taken from Goetschalckx and Jacobs- Blecha is done by using Microsoft C++ Programming. Solutions to the problem are presented and performance comparison is conducted with the existing best solution. Several parameters in GA will be tested such as population size, crossover point and also the choice of operators used.
Classification of Ship Routing and Scheduling Problems in Liner Shipping
DEFF Research Database (Denmark)
Kjeldsen, Karina Hjortshøj
2011-01-01
This article provides a classification scheme for ship routing and scheduling problems in liner shipping in line with the current and future operational conditions of the liner shipping industry. Based on the classification, the literature is divided into groups whose main characteristics...
The dynamic multi-period vehicle routing problem
DEFF Research Database (Denmark)
Wen, Min; Cordeau, Jean-Francois; Laporte, Gilbert;
2010-01-01
This paper considers the Dynamic Multi-Period Vehicle Routing Problem which deals with the distribution of orders from a depot to a set of customers over a multi-period time horizon. Customer orders and their feasible service periods are dynamically revealed over time. The objectives...
The Dynamic Multi-Period Vehicle Routing Problem
DEFF Research Database (Denmark)
Wen, Min; Cordeau, Jean-Francois; Laporte, Gilbert;
This paper considers the Dynamic Multi-Period Vehicle Routing Problem which deals with the distribution of orders from a depot to a set of customers over a multi-period time horizon. Customer orders and their feasible service periods are dynamically revealed over time. The objectives...
Practical inventory routing: A problem definition and an optimization method
Geiger, Martin Josef
2011-01-01
The global objective of this work is to provide practical optimization methods to companies involved in inventory routing problems, taking into account this new type of data. Also, companies are sometimes not able to deal with changing plans every period and would like to adopt regular structures for serving customers.
FUNDAMENTAL PROBLEMS IN PULSED-BIAS ARC DEPOSITION
Institute of Scientific and Technical Information of China (English)
G.Q.Lin; Z.F.Ding; D.Qi; N.H.Wang; M.D.Huang; D.Z.Wang; Y.N.Wang; C.Dong; L.S.Wen
2002-01-01
Arc deposition, a widely used surface coating technique, has disadvantages such aslarge droplet size and high deposition temperature. Recent trend in its renovation isthe introduction of pulsed bias at the substrate. The present paper attempts to describethe deposition process of TiN films using this technique with emphasis laid on theunderstanding of the basic problems such as discharge plasma properties, temperaturecalculation, and droplet size reduction. We show that this technique improves thefilm microstructure and quality, lowers deposition temperature, and allows coatingson insulating substrates. After analyzing load current oscillation behaviors, we havedetermined that the plasma load is of capacitance nature due to plasma sheath and thatit is equivalent to a circuit element consisting of parallel capacitance and resistance.At last, we point out the remaining problems and future development of the pulsed-biasarc deposition technique.
Modeling a four-layer location-routing problem
Directory of Open Access Journals (Sweden)
Mohsen Hamidi
2012-01-01
Full Text Available Distribution is an indispensable component of logistics and supply chain management. Location-Routing Problem (LRP is an NP-hard problem that simultaneously takes into consideration location, allocation, and vehicle routing decisions to design an optimal distribution network. Multi-layer and multi-product LRP is even more complex as it deals with the decisions at multiple layers of a distribution network where multiple products are transported within and between layers of the network. This paper focuses on modeling a complicated four-layer and multi-product LRP which has not been tackled yet. The distribution network consists of plants, central depots, regional depots, and customers. In this study, the structure, assumptions, and limitations of the distribution network are defined and the mathematical optimization programming model that can be used to obtain the optimal solution is developed. Presented by a mixed-integer programming model, the LRP considers the location problem at two layers, the allocation problem at three layers, the vehicle routing problem at three layers, and a transshipment problem. The mathematical model locates central and regional depots, allocates customers to plants, central depots, and regional depots, constructs tours from each plant or open depot to customers, and constructs transshipment paths from plants to depots and from depots to other depots. Considering realistic assumptions and limitations such as producing multiple products, limited production capacity, limited depot and vehicle capacity, and limited traveling distances enables the user to capture the real world situations.
Vehicle routing problem with time-varying speed
Institute of Scientific and Technical Information of China (English)
LIU Yun-zhong
2010-01-01
Vehicle routing problem with time-varying speed(VRPTS)is a generalization of vehicle routing problem in which the travel speed between two locations depends on the passing areas and the time of a day.This paper proposes a simple model for estimating time-varying travel speeds in VRPTS that relieves much bur den to the data-related problems.The study further presents three heuristics(saving technique,proximity priority searching technique,and insertion technique)for VRPTS,developed by extending and modifying the existing heuristics for conventional VRP.The results of computational experiments demonstrate that the proposed estimation model performs well and the saving technique is the best among the three heuristics.
Dynamic Air Route Open-Close Problem for Airspace Management
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Dynamic airspace management plans and assigns airspace resources to airspace users on demand to increase airspace capacity. Although many studies of air traffic flow management (ATFM) have sought to optimally allocate air traffic to get the best use of given airspace resources, few studies have focused on how to build an efficient air traffic network or how to adjust the current network in real time. This paper presents an integer program model named the dynamic air route open-close problem (DROP). DROP has a cost-based objective function which takes into account constraints such as the shortest occupancy time of routes, which are not considered in ATFM models. The aim of DROP is to determine which routes will be opened to a certain user during a given time period. Simulation results show that DROP can facilitate utilization of air routes. DROP, a simplified version of an air traffic network constructing problem, is the first step towards realizing dynamic airspace management. The combination of ATFM and DROP can facilitate decisions toward more reasonable, efficient use of limited airspace resources.
ACTIVITY-BASED COSTING FOR VEHICLE ROUTING PROBLEMS
Directory of Open Access Journals (Sweden)
A. J. Moolman
2012-01-01
Full Text Available
ENGLISH ABSTRACT:Activity-based costing (ABC is a costing model that identifies activity costs in an organisation. It assigns the cost of activity resources to generate the actual cost of products in order to eliminateunprofitable products and to lowerthe prices of overpriced ones. The vehicle routing problem (VRP is a combinatorial optimisation and nonlinear programming problem that seeks to service a number of customers with a fleet of vehicles in a cost-effective manner. In this article we propose a new approach to determine costing for vehicle routing type problems. The methodology incorporates the predictive sharing of a resource by clustering producers.
AFRIKAANSE OPSOMMING: ‘Activity-based costing’ (ABC is ’n kostemodel wat die aktiwiteitskoste in ’n organisasie identifiseer. Dit allokeer die koste van die bronne sodat die ware koste van die vervaardiging en dienste van die produk bereken kan word om winsgewendheid te bepaal. Die ‘vehicle routing problem’ (VRP is ’n kombinatoriese optimisering en nie-lineêre programmeringsprobleem wat verskeie kliënte met ’n vloot voertuie in die mees koste- effektiewe manier bedien. Die artikel bespreek ’n nuwe metode om die kombinasie van probleme op te los. Die metode maak gebruik van groeperingsalgoritmes om meer akkurate voertuig deling te voorspel.
Performansi Algoritma CODEQ dalam Penyelesaian Vehicle Routing Problem
Directory of Open Access Journals (Sweden)
Annisa Kesy Garside
2014-01-01
Full Text Available Genetic Algorithm, Tabu Search, Simulated Annealing, and Ant Colony Optimization showed a good performance in solving vehicle routing problem. However, the generated solution of those algorithms was changeable regarding on the input parameter of each algorithm. CODEQ is a new, parameter free meta-heuristic algorithm that had been successfully used to solve constrained optimization problems, integer programming, and feed-forward neural network. The purpose of this research are improving CODEQ algorithm to solve vehicle routing problem and testing the performance of the improved algorithm. CODEQ algorithm is started with population initiation as initial solution, generated of mutant vector for each parent in every iteration, replacement of parent by mutant when fitness function value of mutant is better than parent’s, generated of new vector for each iteration based on opposition value or chaos principle, replacement of worst solution by new vector when fitness function value of new vector is better, iteration ceasing when stooping criterion is achieved, and sub-tour determination based on vehicle capacity constraint. The result showed that the average deviation of the best-known and the best-test value is 6.35%. Therefore, CODEQ algorithm is good in solving vehicle routing problem.
Enhanced ant colony optimization for inventory routing problem
Wong, Lily; Moin, Noor Hasnah
2015-10-01
The inventory routing problem (IRP) integrates and coordinates two important components of supply chain management which are transportation and inventory management. We consider a one-to-many IRP network for a finite planning horizon. The demand for each product is deterministic and time varying as well as a fleet of capacitated homogeneous vehicles, housed at a depot/warehouse, delivers the products from the warehouse to meet the demand specified by the customers in each period. The inventory holding cost is product specific and is incurred at the customer sites. The objective is to determine the amount of inventory and to construct a delivery routing that minimizes both the total transportation and inventory holding cost while ensuring each customer's demand is met over the planning horizon. The problem is formulated as a mixed integer programming problem and is solved using CPLEX 12.4 to get the lower and upper bound (best integer) for each instance considered. We propose an enhanced ant colony optimization (ACO) to solve the problem and the built route is improved by using local search. The computational experiments demonstrating the effectiveness of our approach is presented.
STUDI TENTANG TRAVELLING SALESMAN DAN VEHICLE ROUTING PROBLEM DENGAN TIME WINDOWS
Directory of Open Access Journals (Sweden)
I Nyoman Sutapa
2003-01-01
Full Text Available The article shows the study of model development of travelling salesman problem. Three models are studied, i.e. travelling salesman problem with time windows, vehicle routing problem, and vehicle routing problem with time windows. Abstract in Bahasa Indonesia : Dalam artikel ini dipaparkan kajian mengenai pengembangan model travelling salesman problem. Ada tiga model yang dikaji yaitu travelling salesman problem dengan time windows, vehicle routing problem, serta vehicle routing problem dengan time windows. Kata-kunci: travelling salesman problem, vehicle routing problem, time windows.
Analysis of the single-vehicle cyclic inventory routing problem
Aghezzaf, El-Houssaine; Zhong, Yiqing; Raa, Birger; Mateo, Manel
2012-11-01
The single-vehicle cyclic inventory routing problem (SV-CIRP) consists of a repetitive distribution of a product from a single depot to a selected subset of customers. For each customer, selected for replenishments, the supplier collects a corresponding fixed reward. The objective is to determine the subset of customers to replenish, the quantity of the product to be delivered to each and to design the vehicle route so that the resulting profit (difference between the total reward and the total logistical cost) is maximised while preventing stockouts at each of the selected customers. This problem appears often as a sub-problem in many logistical problems. In this article, the SV-CIRP is formulated as a mixed-integer program with a nonlinear objective function. After a thorough analysis of the structure of the problem and its features, an exact algorithm for its solution is proposed. This exact algorithm requires only solutions of linear mixed-integer programs. Values of a savings-based heuristic for this problem are compared to the optimal values obtained for a set of some test problems. In general, the gap may get as large as 25%, which justifies the effort to continue exploring and developing exact and approximation algorithms for the SV-CIRP.
Parallelization of the Vehicle Routing Problem with Time Windows
DEFF Research Database (Denmark)
Larsen, Jesper
1999-01-01
This dissertation presents a number of algorithms for solving the Vehicle Routing Problem with Time Windows (VRPTW). The VRPTW is a generalization of the well known capacity constrained Vehicle Routing Problem (VRP). In the VRP a fleet of vehicles based at a central depot must service a set...... of customers. In the VRPTW each customer has a time window. Service of a customer must begin within the interval given by the time window. The objective is to minimize some aspect of operating costs (e.g. total distance traveled, number of vehicles needed or a combination of parameters). Since the late 80's...... and the beginning of the 90's optimal methods for the VRPTW have appeared in the literature. Methods have basicly been based on three approaches: dynamic programming, Lagrange relaxation and column generation (Dantzig-Wolfe). The most successful approaches rely on column generation. Good results have also been...
Vehicle Coordinated Strategy for Vehicle Routing Problem with Fuzzy Demands
Directory of Open Access Journals (Sweden)
Chang-shi Liu
2016-01-01
Full Text Available The vehicle routing problem with fuzzy demands (VRPFD is considered. A fuzzy reasoning constrained program model is formulated for VRPFD, and a hybrid ant colony algorithm is proposed to minimize total travel distance. Specifically, the two-vehicle-paired loop coordinated strategy is presented to reduce the additional distance, unloading times, and waste capacity caused by the service failure due to the uncertain demands. Finally, numerical examples are presented to demonstrate the effectiveness of the proposed approaches.
Choosing offshore pipeline routes: problems and solutions. Final report
Energy Technology Data Exchange (ETDEWEB)
Gowen, A.M.; Goetz, M.J.; Waitsman, I.M.
1980-05-01
The report discusses the environmental and fisheries problems associated with offshore pipelines. The report focuses on how these problems can be addressed during the pipeline planning and route selection process. Geologic hazards are highlighted as the major factors related to pipeline failure which can be addressed through the pipeline routing process. Habitats and ecosystems are particularly susceptible to installation-related disturbances. These areas as well as those where geologic hazards are most likely to be encountered are described. Fishing problems highlighted include loss of access to fishing areas due to pipelines both from platform to shore and between platforms. The effects of obstructions on bottom fishing gear are also considered. The concept of pipeline trenching for safety and stability is discussed. Finally, criteria to use in analyzing a proposed pipeline route are presented. Topics discussed include general industry siting criteria, geologic and environmental areas to avoid in pipeline siting and methods for minimizing unavoidable impacts. The report is designed to be used by scientists or engineers involved in offshore petroleum pipeline planning.
Investigation of Voltage Unbalance Problems In Electric Arc Furnace Operation Model
Directory of Open Access Journals (Sweden)
Yacine DJEGHADER
2013-06-01
Full Text Available In modern steel industry, Electric Arc Furnaces are widely used for iron and scarp melting. The operation of electric arc furnace causes many power quality problems such as harmonics, unbalanced voltage and flicker. The factors that affect Electric arc furnace operation are the melting or refining materials, melting stage, electrodes position (arc length, electrode arm control and short circuit power of the feeder, so, arc voltages, current and power are defined as a nonlinear function of arc length. This study focuses on investigation of unbalanced voltage due to Electrics Arc Furnace operation mode. The simulation results show the major problem of unbalanced voltage affecting secondary of furnace transformer is caused by the different continues movement of electrodes.
On the vehicle routing problem with time windows
Kallehauge, Brian; Madsen, Oli B.G.; Larsen, Jesper; Madsen, Kaj
2006-01-01
Den danske titel på denne afhandling er ‘Ruteplanlægningsproblemet med tidsvinduer’. Dette problem omhandler den optimale styring af en flåde af lastbiler mellem et lager og et antal kunder, der skal besøges inden for et bestemt tidsinterval, et såkaldt tidsvindue. Formålet med denne afhandling er udvikling af nye og effektive metoder til løsning af ruteplanlægningsproblemet med tidsvinduer (vehicle routing problem with time windows - VRPTW). Afhandlingen består af et afsnit af introducerende...
Dynamic vehicle routing problems: Three decades and counting
DEFF Research Database (Denmark)
Psaraftis, Harilaos N.; Wen, Min; Kontovas, Christos A.
2016-01-01
Since the late 70s, much research activity has taken place on the class of dynamic vehicle routing problems (DVRP), with the time period after year 2000 witnessing a real explosion in related papers. Our paper sheds more light into work in this area over more than 3 decades by developing a taxonomy...... of DVRP papers according to 11 criteria. These are (1) type of problem, (2) logistical context, (3) transportation mode, (4) objective function, (5) fleet size, (6) time constraints, (7) vehicle capacity constraints, (8) the ability to reject customers, (9) the nature of the dynamic element, (10...
Reachability cuts for the vehicle routing problem with time windows
DEFF Research Database (Denmark)
Lysgaard, Jens
2004-01-01
This paper introduces a class of cuts, called reachability cuts, for the Vehicle Routing Problem with Time Windows (VRPTW). Reachability cuts are closely related to cuts derived from precedence constraints in the Asymmetric Traveling Salesman Problem with Time Windows and to k-path cuts for the...... VRPTW. In particular, any reachability cut dominates one or more k-path cuts. The paper presents separation procedures for reachability cuts and reports computational experiments on well-known VRPTW instances. The computational results suggest that reachability cuts can be highly useful as cutting...
The Cyclic-Routing UAV Problem is PSPACE-Complete
Ho, Hsi-Ming; Ouaknine, Joel
2014-01-01
Consider a finite set of targets, with each target assigned a relative deadline, and each pair of targets assigned a fixed transit flight time. Given a flock of identical UAVs, can one ensure that every target is repeatedly visited by some UAV at intervals of duration at most the target's relative deadline? The Cyclic-Routing UAV Problem (CR-UAV) is the question of whether this task has a solution. This problem can straightforwardly be solved in PSPACE by modelling it as a network of timed au...
SOLVING THE PROBLEM OF VEHICLE ROUTING BY EVOLUTIONARY ALGORITHM
Directory of Open Access Journals (Sweden)
Remigiusz Romuald Iwańkowicz
2016-03-01
Full Text Available In the presented work the vehicle routing problem is formulated, which concerns planning the collection of wastes by one garbage truck from a certain number of collection points. The garbage truck begins its route in the base point, collects the load in subsequent collection points, then drives the wastes to the disposal site (landfill or sorting plant and returns to the another visited collection points. The filled garbage truck each time goes to the disposal site. It returns to the base after driving wastes from all collection points. Optimization model is based on genetic algorithm where individual is the whole garbage collection plan. Permutation is proposed as the code of the individual.
Ant Colony Optimization for Capacitated Vehicle Routing Problem
Directory of Open Access Journals (Sweden)
H. V. Seow
2012-01-01
Full Text Available Problem statement: The Capacitated Vehicle Routing Problem (CVRP is a well-known combinatorial optimization problem which is concerned with the distribution of goods between the depot and customers. It is of economic importance to businesses as approximately 10-20% of the final cost of the goods is contributed by the transportation process. Approach: This problem was tackled using an Ant Colony Optimization (ACO combined with heuristic approaches that act as the route improvement strategies. The proposed ACO utilized a pheromone evaporation procedure of standard ant algorithm in order to introduce an evaporation rate that depends on the solutions found by the artificial ants. Results: Computational experiments were conducted on benchmark data set and the results obtained from the proposed algorithms shown that the application of combination of two different heuristics in the ACO had the capability to improve the ants solutions better than ACO embedded with only one heuristic. Conclusion: ACO with swap and 3-opt heuristic has the capability to tackle the CVRP with satisfactory solution quality and run time. It is a viable alternative for solving the CVRP.
Separable cross decomposition to solve the assign–routing problem
Directory of Open Access Journals (Sweden)
M. Elizondo–Cortés
2008-01-01
Full Text Available The Inventory–Routing Problem emerges on a logistical context, that is presented into the companies and that it seeks to satisfy the demands of a group of clients distributed geographically, using a flotilla of vehicles of limited capacity, which are in a central ware house, at the small est possible cost. The IRP is a NP–hard problem that is usually great size in real applications. For its solution was designed an strategy that uses of combined form, the crossed de composition and the separable Lagrangean relaxation in order to solve the assign–distribution phase, with what it is obtained a ping–pong type scheme between two subproblems, which are from transport type, with which it is obtained a very efficient algorithm of order O(n3 and easy to implement for the complete problem.
A green vehicle routing problem with customer satisfaction criteria
Afshar-Bakeshloo, M.; Mehrabi, A.; Safari, H.; Maleki, M.; Jolai, F.
2016-08-01
This paper develops an MILP model, named Satisfactory-Green Vehicle Routing Problem. It consists of routing a heterogeneous fleet of vehicles in order to serve a set of customers within predefined time windows. In this model in addition to the traditional objective of the VRP, both the pollution and customers' satisfaction have been taken into account. Meanwhile, the introduced model prepares an effective dashboard for decision-makers that determines appropriate routes, the best mixed fleet, speed and idle time of vehicles. Additionally, some new factors evaluate the greening of each decision based on three criteria. This model applies piecewise linear functions (PLFs) to linearize a nonlinear fuzzy interval for incorporating customers' satisfaction into other linear objectives. We have presented a mixed integer linear programming formulation for the S-GVRP. This model enriches managerial insights by providing trade-offs between customers' satisfaction, total costs and emission levels. Finally, we have provided a numerical study for showing the applicability of the model.
Cooperative vehicle routing problem: an opportunity for cost saving
Zibaei, Sedighe; Hafezalkotob, Ashkan; Ghashami, Seyed Sajad
2016-02-01
In this paper, a novel methodology is proposed to solve a cooperative multi-depot vehicle routing problem. We establish a mathematical model for multi-owner VRP in which each owner (i.e. player) manages single or multiple depots. The basic idea consists of offering an option that owners cooperatively manage the VRP to save their costs. We present cooperative game theory techniques for cost saving allocations which are obtained from various coalitions of owners. The methodology is illustrated with a numerical example in which different coalitions of the players are evaluated along with the results of cooperation and cost saving allocation methods.
A Survey of the Routing and Wavelength Assignment Problem
DEFF Research Database (Denmark)
Gamst, Mette
When transmitting data in an all-optical network, data connections must be established in such a way that two or more connections never share a wavelength on the same fi ber. The NP-hard Routing and Wavelength Assignment (RWA) problem consists of finding paths and wavelengths for a set of data...... connections. This survey introduces the RWA and gives an overview of heuristic, metaheuristic and exact solution methods from the literature. Running times for the heuristic methods are presented and computational results are discussed....
Y. Yu (Yugang); C. Chu (Chengbin); H.X. Chen (Haoxun); F. Chu (Feng)
2010-01-01
textabstractA stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, for a depot to determine delivery volumes to its customers in each period, and vehicle routes to distribute the delivery volumes. This
Large scale stochastic inventory routing problems with split delivery and service level constraints
Y. Yu (Yugang); C. Chu (Chengbin); H.X. Chen (Haoxun); F. Chu (Feng)
2010-01-01
textabstractA stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, which determines delivery volumes to the customers that the depot serves in each period, and vehicle routes to deliver the volumes. Th
A Capacitated Location Routing Problem with Semi Soft Time Windows
Directory of Open Access Journals (Sweden)
Maryam Gharavani
2015-03-01
Full Text Available In this article we address The Location Routing Problem (LRP, where there is a set of customers with known demand and a set of potential depot site and there is a set of heterogeneous vehicle with a certain capacity. Due to the similarity of the problem with real world, the constraints of depot capacity and vehicle capacity as well as route length have been considered simultaneously. The model provided in this article is described concerning the semi soft time window in which that a delay in service delivery time results in delay costs. The total costs in the proposed model include, the total fixed costs of construction depot, fixed costs associated with the use of vehicles, the total distance traveled by the vehicles, the total time within the system for the vehicle and penalty cost associated with the violation of working hour of vehicles and penalty costs associated with delay time in the start of service to customers and the aim is to minimize the total cost. Due to its complexity, two Meta-Heuristic algorithms of Genetic and Tabu Search algorithm have been used. Since the performance of the Meta-Heuristic algorithms is significantly influenced by their parameters, Taguchi Method is used to set the parameters of developed algorithms. Finally, the result represents that the Genetic Algorithm and Tabu Search are significantly efficient in terms of better quality of solution and computational time respectively.
A Mixed Integer Linear Program for Solving a Multiple Route Taxi Scheduling Problem
Montoya, Justin Vincent; Wood, Zachary Paul; Rathinam, Sivakumar; Malik, Waqar Ahmad
2010-01-01
Aircraft movements on taxiways at busy airports often create bottlenecks. This paper introduces a mixed integer linear program to solve a Multiple Route Aircraft Taxi Scheduling Problem. The outputs of the model are in the form of optimal taxi schedules, which include routing decisions for taxiing aircraft. The model extends an existing single route formulation to include routing decisions. An efficient comparison framework compares the multi-route formulation and the single route formulation. The multi-route model is exercised for east side airport surface traffic at Dallas/Fort Worth International Airport to determine if any arrival taxi time savings can be achieved by allowing arrivals to have two taxi routes: a route that crosses an active departure runway and a perimeter route that avoids the crossing. Results indicate that the multi-route formulation yields reduced arrival taxi times over the single route formulation only when a perimeter taxiway is used. In conditions where the departure aircraft are given an optimal and fixed takeoff sequence, accumulative arrival taxi time savings in the multi-route formulation can be as high as 3.6 hours more than the single route formulation. If the departure sequence is not optimal, the multi-route formulation results in less taxi time savings made over the single route formulation, but the average arrival taxi time is significantly decreased.
Directory of Open Access Journals (Sweden)
Yu Lin
2015-01-01
Full Text Available High frequency and small lot size are characteristics of milk runs and are often used to implement the just-in-time (JIT strategy in logistical systems. The common frequency problem, which simultaneously involves planning of the route and frequency, has been extensively researched in milk run systems. In addition, vehicle type choice in the milk run system also has a significant influence on the operating cost. Therefore, in this paper, we simultaneously consider vehicle routing planning, frequency planning, and vehicle type choice in order to optimize the sum of the cost of transportation, inventory, and dispatch. To this end, we develop a mathematical model to describe the common frequency problem with vehicle type choice. Since the problem is NP hard, we develop a two-phase heuristic algorithm to solve the model. More specifically, an initial satisfactory solution is first generated through a greedy heuristic algorithm to maximize the ratio of the superior arc frequency to the inferior arc frequency. Following this, a tabu search (TS with limited search scope is used to improve the initial satisfactory solution. Numerical examples with different sizes establish the efficacy of our model and our proposed algorithm.
DULLAERT, Wout
2000-01-01
In this paper we study the performance of Solomon’s (1987) sequential insertion heuristic |1, for Vehicle Routing Problems with Time Windows (VRPTWs) in which the number of customers per rout is small with respect to the customers’ time windows and the scheduling horizon. Solomon’s (1987) time insertion c12 (i, u, j) underestimates the additional time needed of inserting a new customer u between the depot, i= i0 and the first customer j in the partially constructed rout (i0= I, i1=j,i1,…,im)....
Sanjeevi, V; Shahabudeen, P
2016-01-01
Worldwide, about US$410 billion is spent every year to manage four billion tonnes of municipal solid wastes (MSW). Transport cost alone constitutes more than 50% of the total expenditure on solid waste management (SWM) in major cities of the developed world and the collection and transport cost is about 85% in the developing world. There is a need to improve the ability of the city administrators to manage the municipal solid wastes with least cost. Since 2000, new technologies such as geographical information system (GIS) and related optimization software have been used to optimize the haul route distances. The city limits of Chennai were extended from 175 to 426 km(2) in 2011, leading to sub-optimum levels in solid waste transportation of 4840 tonnes per day. After developing a spatial database for the whole of Chennai with 200 wards, the route optimization procedures have been run for the transport of solid wastes from 13 wards (generating nodes) to one transfer station (intermediary before landfill), using ArcGIS. The optimization process reduced the distances travelled by 9.93%. The annual total cost incurred for this segment alone is Indian Rupees (INR) 226.1 million. Savings in terms of time taken for both the current and shortest paths have also been computed, considering traffic conditions. The overall savings are thus very meaningful and call for optimization of the haul routes for the entire Chennai. PMID:26467317
Sanjeevi, V; Shahabudeen, P
2016-01-01
Worldwide, about US$410 billion is spent every year to manage four billion tonnes of municipal solid wastes (MSW). Transport cost alone constitutes more than 50% of the total expenditure on solid waste management (SWM) in major cities of the developed world and the collection and transport cost is about 85% in the developing world. There is a need to improve the ability of the city administrators to manage the municipal solid wastes with least cost. Since 2000, new technologies such as geographical information system (GIS) and related optimization software have been used to optimize the haul route distances. The city limits of Chennai were extended from 175 to 426 km(2) in 2011, leading to sub-optimum levels in solid waste transportation of 4840 tonnes per day. After developing a spatial database for the whole of Chennai with 200 wards, the route optimization procedures have been run for the transport of solid wastes from 13 wards (generating nodes) to one transfer station (intermediary before landfill), using ArcGIS. The optimization process reduced the distances travelled by 9.93%. The annual total cost incurred for this segment alone is Indian Rupees (INR) 226.1 million. Savings in terms of time taken for both the current and shortest paths have also been computed, considering traffic conditions. The overall savings are thus very meaningful and call for optimization of the haul routes for the entire Chennai.
DEFF Research Database (Denmark)
Larsen, Jesper
2002-01-01
Two ideas for using structural information for solving the Vehicle Routing Problem with Time Windows (VRPTW) is presented. The VRPTW is a generalization of the well known capacity constrained Vehicle Routing Problem (VRP). Both techniques are based on solving the VRPTW using a Branch...
A Hybrid TCNN Optimization Approach for the Capacity Vehicle Routing Problem
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A novel approximation algorithm was proposed for the problem of finding the minimum total cost of all routes in Capacity Vehicle Routing Problem (CVRP). CVRP can be partitioned into three parts: the selection of vehicles among the available vehicles, the initial routing of the selected fleet and the routing optimization. Fuzzy Cmeans (FCM) can group the customers with close Euclidean distance into the same vehicle according to the principle of similar feature partition. Transiently chaotic neural network (TCNN) combines local search and global search, possessing high search efficiency. It will solve the routes to near optimality. A simple tabu search (TS)procedure can improve the routes to more optimality. The computations on benchmark problems and comparisons with other results in literatures show that the proposed algorithm is a viable and effective approach for CVRP.
A branch-and-cut-and-price algorithm for the cumulative capacitated vehicle routing problem
DEFF Research Database (Denmark)
Wøhlk, Sanne; Lysgaard, Jens
2014-01-01
The paper considers the Cumulative Capacitated Vehicle Routing Problem (CCVRP), which is a variation of the well-known Capacitated Vehicle Routing Problem (CVRP). In this problem, the traditional objective of minimizing total distance or time traveled by the vehicles is replaced by minimizing the...... the sum of arrival times at the customers. A branch-and-cut-and-price algorithm for obtaining optimal solutions to the problem is proposed. Computational results based on a set of standard CVRP benchmarks are presented.......The paper considers the Cumulative Capacitated Vehicle Routing Problem (CCVRP), which is a variation of the well-known Capacitated Vehicle Routing Problem (CVRP). In this problem, the traditional objective of minimizing total distance or time traveled by the vehicles is replaced by minimizing...
Problems in the Information Dissemination of the Internet Routing
Institute of Scientific and Technical Information of China (English)
ZHAO YiXin(赵邑新); YIN Xia(尹霞); WU JianPing(吴建平)
2003-01-01
Internet routing is achieved by a set of nodes running distributed algorithms -routing protocols. However, many nodes are resistless to wrong messages or improper operations,unable to detect or correct them. Thus a wrong message or an improper operation can easilysweep almost the whole Internet. Such a fragile Internet routing comes from the features of thesealgorithms and protocols. Besides, the strategies taken by the network equipment manufacturersand administrators also are of important influence. When determining the options or selectionsin the implementation/operation, they always pay more attention to the expense of a single nodeor a single area and make some simplifications in implementations and configurations while caringless about the influence on the whole network. This paper tries to illustrate such a scheme is notreasonable at all and suggests the consideration from the view of the overall optimization. Fromthree typical cases involved in the Internet routing, a general model is abstracted, which makes theresults signiflcative for more Internet related aspects. This paper evaluates the complexity of thetheoretical analysis, then acquires the effect of error information on the whole network through thesimulation on the Internet topology. It is shown that even very little error information can incursevere impact on the Internet. And it will take much more efforts of downstream nodes to makeremedies. This result is intuitively revealed through the comparisons in the charts and the visualpresentations. Then a hierarchical solution to establish the upgrade plan is given, which helps toupgrade the nodes of the network in a most efficient and economical way.
A branch-and-cut algorithm for the capacitated open vehicle routing problem
DEFF Research Database (Denmark)
Letchford, A.N.; Lysgaard, Jens; Eglese, R.W.
2007-01-01
In open vehicle routing problems, the vehicles are not required to return to the depot after completing service. In this paper, we present the first exact optimization algorithm for the open version of the well-known capacitated vehicle routing problem (CVRP). The algorithm is based on branch...... assess the quality of existing heuristic methods, and to compare the relative difficulty of open and closed versions of the same problem....
A Branch-and-Cut Algorithm for the Capacitated Open Vehicle Routing Problem
DEFF Research Database (Denmark)
Letchford, Adam N.; Lysgaard, Jens; Eglese, Richard W.
In open vehicle routing problems, the vehicles are not required to return to the depot after completing service. In this paper, we present the first exact optimization algorithm for the open version of the well-known capacitated vehicle routing problem (CVRP). The algorithm is based on branch...... assess the quality of existing heuristic methods, and to compare the relative difficulty of open and closed versions of the same problem....
Hybrid discrete particle swarm optimization algorithm for capacitated vehicle routing problem
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Capacitated vehicle routing problem (CVRP) is an NP-hard problem. For large-scale problems, it is quite difficult to achieve an optimal solution with traditional optimization methods due to the high computational complexity. A new hybrid approximation algorithm is developed in this work to solve the problem. In the hybrid algorithm, discrete particle swarm optimization (DPSO) combines global search and local search to search for the optimal results and simulated annealing (SA) uses certain probability to avoid being trapped in a local optimum. The computational study showed that the proposed algorithm is a feasible and effective approach for capacitated vehicle routing problem, especially for large scale problems.
What Is the Best Route? Route-Finding Strategies of Middle School Students Using GIS
Wigglesivorth, John C.
2003-01-01
This paper summarizes a research project conducted to investigate the strategies developed by middle school students to solve a route-finding problem using Arc View GIS software. Three different types of route-finding strategies were identified. Some students were visual route-finders and used a highly visual strategy; others were logical route…
Optimization of Capacitated Vehicle Routing Problem by Nested Particle Swarm Optimization
Directory of Open Access Journals (Sweden)
Karuppusamy Kanthavel
2011-01-01
Full Text Available Problem statement: Vehicle routing problem determines the optimum route for each vehicle as a sequence of visiting cities. The problem has been defined as NP-hard and exact solution is relatively difficult to achieve for real time large scale models. Though several attempts to solve the problem were made in the literature, new approaches may be tried to solve the problem to further reduce computational efforts. Approach: In this context this study focuses on maximum utilization of loading capacity and determines the optimum set of vehicle routes for Capacitated Vehicle Routing Problem (CVRP by a Nested Particle Swarm Optimization (NPSO technique. The algorithm is implemented as Master PSO and slave PSO for the identification of candidate list and route sequence in nested form to optimize the model. Results: Benchmarking data set of capacitated vehicle routing is considered for the evaluations. The total distance of set vehicle route obtained by the new approach is compared with the best known solution and other existing techniques. Conclusions/Recommendations: The NPSO produces significant results and computational performance than the existing PSO algorithms. This newly proposed NPSO algorithm develops the vehicle schedule without any local optimization technique.
Formulations and Branch-and-Cut Algorithms for the Generalized Vehicle Routing Problem
DEFF Research Database (Denmark)
Bektas, Tolga; Erdogan, Günes; Røpke, Stefan
2011-01-01
The Generalized Vehicle Routing Problem (GVRP) consists of nding a set of routes for a number of vehicles with limited capacities on a graph with the vertices partitioned into clusters with given demands such that the total cost of travel is minimized and all demands are met. This paper offers four...
The waste collection vehicle routing problem with time windows in a city logistics context
DEFF Research Database (Denmark)
Buhrkal, Katja Frederik; Larsen, Allan; Røpke, Stefan
2012-01-01
Collection of waste is an important logistic activity within any city. In this paper we study how to collect waste in an efficient way. We study the Waste Collection Vehicle Routing Problem with Time Window which is concerned with finding cost optimal routes for garbage trucks such that all garba...
Directory of Open Access Journals (Sweden)
V.PURUSHOTHAM REDDY
2011-02-01
Full Text Available In computer networks the routing is based on shortest path routing algorithms. Based on its advantages, an alternative method is used known as Genetic Algorithm based routing algorithm, which is highly scalable and insensitive to variations in network topology. Here we propose a coarse-grained parallel genetic algorithm to solve the shortest path routing problem with the primary goal of computation time reduction along with the use of migration scheme. This algorithm is developed and implemented on an MPI cluster. The effects of migration and its performance is studied in this paper.
Research on multi-objective emergency logistics vehicle routing problem under constraint conditions
Miaomiao Du; Hua Yi
2013-01-01
Purpose: Aim at choosing a relative good vehicle routing in emergency conditions under constraint conditions when disaster happens. Rapid response and rescue can save a lot of people. Design/methodology/approach: Modeling analysis: establishing a mathematical model of multi-objective emergency logistics vehicle routing problem. And in end of the paper, we intend to use genetic algorithms to solve the problem. Findings: Considering time requirement and cost limit both while choosing vehicle ro...
New Lower Bounds on the Number of Vehicles for the Vehicle Routing Problem with Time Windows
Afifi, Sohaib; Guibadj, Rym Nesrine; Moukrim, Aziz
2014-01-01
International audience; The Vehicle Routing Problem with Time Windows (VRPTW) consists in determining the routing plan of vehicles with identical capacity in order to supply the demands of a set of customers with predefined time windows. This complex multi-constrained problem has been widely studied due to its industrial, economic and environmental implications. In this work, we are interested in defining the number of vehicles needed to visit all the customers. This objective is very importa...
Solving the Tractor and Semi-Trailer Routing Problem Based on a Heuristic Approach
Hongqi Li; Yue Lu; Jun Zhang; Tianyi Wang
2012-01-01
We study the tractor and semi-trailer routing problem (TSRP), a variant of the vehicle routing problem (VRP). In the TSRP model for this paper, vehicles are dispatched on a trailer-flow network where there is only one main depot, and all tractors originate and terminate in the main depot. Two types of decisions are involved: the number of tractors and the route of each tractor. Heuristic algorithms have seen widespread application to various extensions of the VRP. However, this approach has n...
A heterogeneous fleet vehicle routing model for solving the LPG distribution problem: A case study
International Nuclear Information System (INIS)
Vehicle Routing Problem (VRP) is an important management problem in the field of distribution and logistics. In VRPs, routes from a distribution point to geographically distributed points are designed with minimum cost and considering customer demands. All points should be visited only once and by one vehicle in one route. Total demand in one route should not exceed the capacity of the vehicle that assigned to that route. VRPs are varied due to real life constraints related to vehicle types, number of depots, transportation conditions and time periods, etc. Heterogeneous fleet vehicle routing problem is a kind of VRP that vehicles have different capacity and costs. There are two types of vehicles in our problem. In this study, it is used the real world data and obtained from a company that operates in LPG sector in Turkey. An optimization model is established for planning daily routes and assigned vehicles. The model is solved by GAMS and optimal solution is found in a reasonable time
A heterogeneous fleet vehicle routing model for solving the LPG distribution problem: A case study
Onut, S.; Kamber, M. R.; Altay, G.
2014-03-01
Vehicle Routing Problem (VRP) is an important management problem in the field of distribution and logistics. In VRPs, routes from a distribution point to geographically distributed points are designed with minimum cost and considering customer demands. All points should be visited only once and by one vehicle in one route. Total demand in one route should not exceed the capacity of the vehicle that assigned to that route. VRPs are varied due to real life constraints related to vehicle types, number of depots, transportation conditions and time periods, etc. Heterogeneous fleet vehicle routing problem is a kind of VRP that vehicles have different capacity and costs. There are two types of vehicles in our problem. In this study, it is used the real world data and obtained from a company that operates in LPG sector in Turkey. An optimization model is established for planning daily routes and assigned vehicles. The model is solved by GAMS and optimal solution is found in a reasonable time.
On the vehicle routing problem with time windows
DEFF Research Database (Denmark)
Kallehauge, Brian
2006-01-01
at the master problem level by Lagrangian relaxation. The result is a Lagrangian branch-andcut- and-price (LBCP) algorithm for the VRPTW. Making use of this acceleration strategy at the master problem level gives a significant speed-up compared to algorithms in the literature based on traditional column...... of the constraint set requiring that each customer must be served by exactly one vehicle yielding a constrained shortest path subproblem. We present a stabilized cutting-plane algorithm within the framework of linear programming for solving the associated Lagrangian dual problem. This algorithm creates easier...... generation. We have solved two test problems introduced in 2001 by Gehring and Homberger with 400 and 1000 customers respectively, which to date are the largest problems ever solved to optimality. We have implemented the LBCP algorithm using the ABACUS open-source framework for solving mixed-integer linear...
Applying AN Integrated Route Optimization Method as a Solution to the Problem of Waste Collection
Salleh, A. H.; Ahamad, M. S. S.; Yusoff, M. S.
2016-09-01
Solid waste management (SWM) is very subjective to budget control where the utmost expenses are devoted to the waste collection's travel route. The common understanding of the travel route in SWM is that shorter route is cheaper. However, in reality it is not necessarily true as the SWM compactor truck is affected by various aspects which leads to higher fuel consumption. Thus, this ongoing research introduces a solution to the problem using multiple criteria route optimization process integrated with AHP/GIS as its main analysis tools. With the criteria obtained from the idea that leads to higher fuel consumption based on road factors, road networks and human factors. The weightage of criteria is obtained from the combination of AHP with the distance of multiple shortest routes obtained from GIS. A solution of most optimum routes is achievable and comparative analysis with the currently used route by the SWM compactor truck can be compared. It is expected that the decision model will be able to solve the global and local travel route problem in MSW.
REFINEMENTS OF THE COLUMN GENERATION PROCESS FOR THE VEHICLE ROUTING PROBLEM WITH TIME WINDOWS
Institute of Scientific and Technical Information of China (English)
Jesper LARSEN
2004-01-01
The Vehicle Routing Problem with Time Windows is a generalization of the well known capacity constrained Vehicle Routing Problem. A homogeneous fleet of vehicles has to service a set of customers. The service of the customers can only start within a well-defined time interval denoted the time window. The objective is to determine routes for the vehicles that minimizes the accumulated cost (or distance). Currently the best approaches for determining optimal solutions are based on column generation and Branch-and-Bound, also known as Branch-and-Price. This paper presents two ideas for run-time improvements of the Branch-and-Price framework for the Vehicle Routing Problem with Time Windows. Both ideas reveal a significant potential for run-time refinements when speeding up an exact approach without compromising optimality.
Location-routing Problem with Fuzzy time windows and Traffic time
Directory of Open Access Journals (Sweden)
Shima Teimoori
2014-05-01
Full Text Available The location-routing problem is a relatively new branch of logistics system. Its objective is to determine a suitable location for constructing distribution warehouses and proper transportation routing from warehouse to the customer. In this study, the location-routing problem is investigated with considering fuzzy servicing time window for each customer. Another important issue in this regard is the existence of congested times during the service time and distributing goods to the customer. This caused a delay in providing service for customer and imposed additional costs to distribution system. Thus we have provided a mathematical model for designing optimal distributing system. Since the vehicle location-routing problem is Np-hard, thus a solution method using genetic meta-heuristic algorithm was developed and the optimal sequence of servicing for the vehicle and optimal location for the warehouses were determined through an example.
DEFF Research Database (Denmark)
Cetin, Bilge Kartal; Prasad, Neeli R.; Prasad, Ramjee
2011-01-01
In wireless sensor networks, one of the key challenge is to achieve minimum energy consumption in order to maximize network lifetime. In fact, lifetime depends on many parameters: the topology of the sensor network, the data aggregation regime in the network, the channel access schemes, the routing...... protocols, and the energy model for transmission. In this paper, we tackle the routing challenge for maximum lifetime of the sensor network. We introduce a novel linear programming approach to the maximum lifetime routing problem. To the best of our knowledge, this is the first mathematical programming...... of the maximum lifetime routing problem that considers the operation modes of the node. Solution of the linear programming gives the upper analytical bound for the network lifetime. In order to illustrate teh application of the optimization model, we solved teh problem for different parameter settings...
A Rounding by Sampling Approach to the Minimum Size k-Arc Connected Subgraph Problem
Laekhanukit, Bundit; Singh, Mohit
2012-01-01
In the k-arc connected subgraph problem, we are given a directed graph G and an integer k and the goal is the find a subgraph of minimum cost such that there are at least k-arc disjoint paths between any pair of vertices. We give a simple (1 + 1/k)-approximation to the unweighted variant of the problem, where all arcs of G have the same cost. This improves on the 1 + 2/k approximation of Gabow et al. [GGTW09]. Similar to the 2-approximation algorithm for this problem [FJ81], our algorithm simply takes the union of a k in-arborescence and a k out-arborescence. The main difference is in the selection of the two arborescences. Here, inspired by the recent applications of the rounding by sampling method (see e.g. [AGM+ 10, MOS11, OSS11, AKS12]), we select the arborescences randomly by sampling from a distribution on unions of k arborescences that is defined based on an extreme point solution of the linear programming relaxation of the problem. In the analysis, we crucially utilize the sparsity property of the ext...
Parallel algorithms for network routing problems and recurrences
Energy Technology Data Exchange (ETDEWEB)
Wisniewski, J.A. (Sandia Labs., Albuquerque, NM); Sameh, A.H.
1982-09-01
In this paper, we consider the parallel solution of recurrences, and linear systems in the regular algebra of Carre. These problems are equivalent to solving the shortest path problem in graph theory, and they also arise in the analysis of Fortran programs. Our methods for solving linear systems in the regular algebra are analogues of well-known methods for solving systems of linear algebraic equations. A parallel version of Dijkstra's method, which has no linear algebraic analogue, is presented. Considerations for choosing an algorithm when the problem is large and sparse are also discussed.
Parallel algorithms for network routing problems and recurrences
International Nuclear Information System (INIS)
In this paper, we consider the parallel solution of recurrences, and linear systems in the regular algebra of Carre. These problems are equivalent to solving the shortest path problem in graph theory, and they also arise in the analysis of Fortran programs. Our methods for solving linear systems in the regular algebra are analogues of well-known methods for solving systems of linear algebraic equations. A parallel version of Dijkstra's method, which has no linear algebraic analogue, is presented. Considerations for choosing an algorithm when the problem is large and sparse are also discussed
The integrated model for solving the single-period deterministic inventory routing problem
Rahim, Mohd Kamarul Irwan Abdul; Abidin, Rahimi; Iteng, Rosman; Lamsali, Hendrik
2016-08-01
This paper discusses the problem of efficiently managing inventory and routing problems in a two-level supply chain system. Vendor Managed Inventory (VMI) policy is an integrating decisions between a supplier and his customers. We assumed that the demand at each customer is stationary and the warehouse is implementing a VMI. The objective of this paper is to minimize the inventory and the transportation costs of the customers for a two-level supply chain. The problem is to determine the delivery quantities, delivery times and routes to the customers for the single-period deterministic inventory routing problem (SP-DIRP) system. As a result, a linear mixed-integer program is developed for the solutions of the SP-DIRP problem.
Enhanced Mixed Integer Programming Techniques and Routing Problems
Tramontani, Andrea
2009-01-01
Mixed integer programming is up today one of the most widely used techniques for dealing with hard optimization problems. On the one side, many practical optimization problems arising from real-world applications (such as, e.g., scheduling, project planning, transportation, telecommunications, economics and finance, timetabling, etc) can be easily and effectively formulated as Mixed Integer linear Programs (MIPs). On the other hand, 50 and more years of intensive research has dramatically ...
On an iterative procedure for solving a routing problem with constraints
Chentsov, A. A.; A. G Chentsov
2013-01-01
The generalized precedence constrained traveling salesman problem is considered in the case when travel costs depend explicitly on the list of tasks that have not been performed (by the time of the travel). The original routing problem with dependent variables is represented in terms of an equivalent extremal problem with independent variables. An iterative method based on this representation is proposed for solving the original problem. The algorithm based on this method is implemented as a ...
The vehicle routing problem with edge set costs
DEFF Research Database (Denmark)
Reinhardt, Line Blander; Jepsen, Mads Kehlet; Pisinger, David
on branch-and-price-and-cut is applied to the problem. The computational results show that instances with up to 50 customers can be solved in reasonable time, and that the branch-cut-and-price algorithm generally outperforms CPLEX. It also seems that instances get more difficult when the penalized edge sets...
RaceTrack: An Approximation Algorithm for the Mobile Sink Routing Problem
Yuan, Yuan; Peng, Yuxing
In large-scale monitoring applications, randomly deployed wireless sensor networks may not be fully connected. Using mobile sink for data collection is one of the feasible solutions. For energy saving, it is necessary to plan a shortest route for the mobile sink. Mobile sink routing problem can be regarded as a special case of TSP with neighborhoods (TSPN) problem. In this paper, we propose a novel approximation algorithm called RaceTrack. This algorithm forms a "racetrack" based on the TSP route, which is constructed from the locations of the deployed sensor nodes. By using inner lane heuristic and concave bend heuristic of auto racing, and a shortcut finding step, we optimize the obtained TSP route within O(n) computation time. Through formal proofs and large-scale simulations, we verified that our RaceTrack algorithm can achieve a good approximation ratio.
Approximate solution of the multiple watchman routes problem with restricted visibility range.
Faigl, Jan
2010-10-01
In this paper, a new self-organizing map (SOM) based adaptation procedure is proposed to address the multiple watchman route problem with the restricted visibility range in the polygonal domain W. A watchman route is represented by a ring of connected neuron weights that evolves in W, while obstacles are considered by approximation of the shortest path. The adaptation procedure considers a coverage of W by the ring in order to attract nodes toward uncovered parts of W. The proposed procedure is experimentally verified in a set of environments and several visibility ranges. Performance of the procedure is compared with the decoupled approach based on solutions of the art gallery problem and the consecutive traveling salesman problem. The experimental results show the suitability of the proposed procedure based on relatively simple supporting geometrical structures, enabling application of the SOM principles to watchman route problems in W.
Nair, T R Gopalakrishnan; Yashoda, M B
2011-01-01
In Internet Routing, the static shortest path (SP) problem has been addressed using well known intelligent optimization techniques like artificial neural networks, genetic algorithms (GAs) and particle swarm optimization. Advancement in wireless communication lead more and more mobile wireless networks, such as mobile networks [mobile ad hoc networks (MANETs)] and wireless sensor networks. Dynamic nature of the network is the main characteristic of MANET. Therefore, the SP routing problem in MANET turns into dynamic optimization problem (DOP). Here the nodes ae made aware of the environmental condition, thereby making it intelligent, which goes as the input for GA. The implementation then uses GAs with immigrants and memory schemes to solve the dynamic SP routing problem (DSPRP) in MANETS. In our paper, once the network topology changes, the optimal solutions in the new environment can be searched using the new immigrants or the useful information stored in the memory. Results shows GA with new immigrants sho...
A route-based decomposition for the Multi-Commodity k-splittable Maximum Flow Problem
DEFF Research Database (Denmark)
Gamst, Mette
2012-01-01
The Multi-Commodity k-splittable Maximum Flow Problem routes flow through a capacitated graph such that each commodity uses at most k paths and such that the total amount of routedflow is maximized. This paper proposes a branch-and-price algorithm based on a route-based Dantzig-Wolfe decomposition......, where a route consists of up to k paths. Computational results show that the new algorithm has best performance on seven benchmark instances and is capable of solving two previously unsolved instances....
A weighted min-max model for balanced freight train routing problem with fuzzy information
Yang, Lixing; Gao, Ziyou; Li, Xiang; Li, Keping
2011-12-01
A multi-objective freight train routing problem with fuzzy information is investigated in this article. To handle the fuzziness in the railway transportation system, the measure ℳλ (i.e. the convex combination of a possibility measure and a necessity measure) is first introduced. Then, a min-max chance-constrained programming model is constructed to obtain optimal train routing plans. In order to solve the model, a potential route algorithm, fuzzy simulation and tabu search algorithm are integrated as a hybrid algorithm. Finally, some numerical experiments are performed to show the applications of the model and the algorithm.
A branch-and-price algorithm for the capacitated vehicle routing problem with stochastic demands
DEFF Research Database (Denmark)
Christiansen, Christian Holk; Lysgaard, Jens
2007-01-01
This article introduces a new exact algorithm for the Capacitated Vehicle Routing Problem with Stochastic Demands (CVRPSD). The CVRPSD can be formulated as a Set Partitioning Problem and it is shown that the associated column generation subproblem can be solved using a dynamic programming scheme...
An Adaptable Variable Neighborhood Search for the Vehicle Routing Problem with Order Outsourcing
Huijink, S.; Kant, G.; Peeters, M.J.P.
2014-01-01
In practice, many package transportation companies lower their costs by hiring outside carriers to serve orders that cannot be served efficiently by their own trucks. The problem which takes the order outsource option into account is the Vehicle Routing Problem with Private Fleet and Common Carrier.
DEFF Research Database (Denmark)
Gamst, M.
2014-01-01
arrived at the machine. Furthermore, two resource demand transmissions cannot use the same edge in the same time period. The problem has application in grid computing, where a number of geographically distributed machines work together for solving large problems. The machines are connected through...... an optical network. The problem is formulated as an IP problem and is shown to be NP-hard. An exact solution approach based on Dantzig-Wolfe decomposition is proposed. Also, several heuristic methods are developed by combining heuristics for the job scheduling problem and for the constrained network routing...... problem. The methods are computationally evaluated on test instances arising from telecommunications with up to 500 jobs and 500 machines. Results show that solving the integrated job scheduling and constrained network routing problem to optimality is very difficult. The exact solution approach performs...
On the Integrated Job Scheduling and Constrained Network Routing Problem
DEFF Research Database (Denmark)
Gamst, Mette
This paper examines the NP-hard problem of scheduling a number of jobs on a finite set of machines such that the overall profit of executed jobs is maximized. Each job demands a number of resources, which must be sent to the executing machine via constrained paths. Furthermore, two resource demand...... transmissions cannot use the same edge in the same time period. An exact solution approach based on Dantzig-Wolfe decomposition is proposed along with several heuristics. The methods are computationally evaluated on test instances arising from telecommunications with up to 500 jobs and 500 machines. Results...
Research on multi-objective emergency logistics vehicle routing problem under constraint conditions
Directory of Open Access Journals (Sweden)
Miaomiao Du
2013-03-01
Full Text Available Purpose: Aim at choosing a relative good vehicle routing in emergency conditions under constraint conditions when disaster happens. Rapid response and rescue can save a lot of people. Design/methodology/approach: Modeling analysis: establishing a mathematical model of multi-objective emergency logistics vehicle routing problem. And in end of the paper, we intend to use genetic algorithms to solve the problem. Findings: Considering time requirement and cost limit both while choosing vehicle routing when the disasters happens is meaningful. We can get a relative good result and give a guidance to rescue teams. Originality/value: Consider cost and time objectives and kinds of realistic conditions (such as the road congestion in the model when solving the problem, having expanded the theory scope.
Vehicle Routing Problem with Backhaul, Multiple Trips and Time Window
Directory of Open Access Journals (Sweden)
Johan Oscar Ong
2011-01-01
Full Text Available Transportation planning is one of the important components to increase efficiency and effectiveness in the supply chain system. Good planning will give a saving in total cost of the supply chain. This paper develops the new VRP variants’, VRP with backhauls, multiple trips, and time window (VRPBMTTW along with its problem solving techniques by using Ant Colony Optimization (ACO and Sequential Insertion as initial solution algorithm. ACO is modified by adding the decoding process in order to determine the number of vehicles, total duration time, and range of duration time regardless of checking capacity constraint and time window. This algorithm is tested by using set of random data and verified as well as analyzed its parameter changing’s. The computational results for hypothetical data with 50% backhaul and mix time windows are reported.
Multidimentional Self-organization for Online Time-Constrained Vehicle Routing Problems
ZEDDINI, B; ZARGAYOUNA, M
2010-01-01
Vehicle Routing problems are highly complex problems for which different Artificial Intelligence techniques have been used. In this paper, we propose two agent-oriented self-organization models for the dynamic version of the problem with time windows. The first model relies on a spatial representation, and the second is based on a space-time representation of the agents' action zones, which are able to maintain a good distribution of the vehicles on the environment. This distribution provides...
Solution to the problem of ant being stuck by ant colony routing algorithm
Institute of Scientific and Technical Information of China (English)
ZHAO Jing; TONG Wei-ming
2009-01-01
Many ant colony routing (ACR) algorithms have been presented in recent years, but few have studied the problem that ants will get stuck with probability in any terminal host when they are searching paths to route packets around a network. The problem has to be faced when designing and implementing the ACR algorithm. This article analyzes in detail the differences between the ACR and the ant colony optimization (ACO). Besides, particular restrictions on the ACR are pointed out and the three causes of ant being-stuck problem are obtained. Furthermore, this article proposes a new ant searching mechanism through dual path-checking and online routing loop removing by every intermediate node an ant visited and the destination host respectively, to solve the problem of ant being stuck and routing loop simultaneously. The result of numerical simulation is abstracted from one real network. Compared with existing two typical ACR algorithms, it shows that the proposed algorithm can settle the problem of ant being stuck and achieve more effective searching outcome for optimization path.
An Investigation of Using Parallel Genetic Algorithm for Solving the Shortest Path Routing Problem
Directory of Open Access Journals (Sweden)
Salman Yussof
2011-01-01
Full Text Available Problem statement: Shortest path routing is the type of routing widely used in computer network nowadays. Even though shortest path routing algorithms are well established, other alternative methods may have their own advantages. One such alternative is to use a GA-based routing algorithm. According to previous researches, GA-based routing algorithm has been found to be more scalable and insensitive to variations in network topologies. However, it is also known that GA-based routing algorithm is not fast enough for real-time computation. Approach: To improve the computation time of GA-based routing algorithm, this study proposes a coarse-grained parallel GA routing algorithm for solving the shortest path routing problem. The proposed algorithm is evaluated using simulation where the proposed algorithm is executed on networks with various topologies and sizes. The parallel computation is performed using an MPI cluster. Three different experiments were conducted to identify the best value for the migration rate, the accuracy and execution time with respect to the number of computing nodes and speedup achieved as compared to the serial version of the same algorithm. Results: The result of the simulation shows that the best result is achieved for a migration rate around 0.1 and 0.2. The experiments also show that with larger number of computing nodes, accuracy decreases linearly, but computation time decreases exponentially, which justifies the use parallel implementation of GA to improve the speed of GA-based routing algorithm. Finally, the experiments also show that the proposed algorithm is able to achieve a speedup of up to 818.11% on the MPI cluster used to run the simulation. Conclusion/Recommendations: We have successfully shown that the performance of GA-based shortest path routing algorithm can be improved by using a coarse-grained parallel GA implementation. Even though in this study the proposed algorithm is executed
The Green Ship Routing and Scheduling Problem (GSRSP): A conceptual approach
DEFF Research Database (Denmark)
Kontovas, Christos A.
2014-01-01
Recent reviews of the literature on ship routing and scheduling note the increased attention to environmental issues. This is an area of paramount importance for international shipping and will be even more so in the future. This short communication is motivated by the increasing attention...... to 'green' routing and scheduling and outlines some possible ways to incorporate the air emissions dimension into maritime transportation OR. The main contribution of this note vis-a-vis the state of the art is that it conceptualizes the formulation of the 'Green Ship Routing and Scheduling Problem' (GSRSP......) based on existing formulations and highlights all the important parameters of the problem. (C) 2014 Elsevier Ltd. All rights reserved....
A Food Chain Algorithm for Capacitated Vehicle Routing Problem with Recycling in Reverse Logistics
Song, Qiang; Gao, Xuexia; Santos, Emmanuel T.
2015-12-01
This paper introduces the capacitated vehicle routing problem with recycling in reverse logistics, and designs a food chain algorithm for it. Some illustrative examples are selected to conduct simulation and comparison. Numerical results show that the performance of the food chain algorithm is better than the genetic algorithm, particle swarm optimization as well as quantum evolutionary algorithm.
Davendra, Donald; Zelinka, Ivan; Senkerik, Roman; Jasek, Roman; Bialic-Davendra, Magdalena
2012-11-01
One of the new emerging application strategies for optimization is the hybridization of existing metaheuristics. The research combines the unique paradigms of solution space sampling of SOMA and memory retention capabilities of Scatter Search for the task of capacitated vehicle routing problem. The new hybrid heuristic is tested on the Taillard sets and obtains good results.
Stochastic time-dependent vehicle routing problem: Mathematical models and ant colony algorithm
Directory of Open Access Journals (Sweden)
Zhengyu Duan
2015-11-01
Full Text Available This article addresses the stochastic time-dependent vehicle routing problem. Two mathematical models named robust optimal schedule time model and minimum expected schedule time model are proposed for stochastic time-dependent vehicle routing problem, which can guarantee delivery within the time windows of customers. The robust optimal schedule time model only requires the variation range of link travel time, which can be conveniently derived from historical traffic data. In addition, the robust optimal schedule time model based on robust optimization method can be converted into a time-dependent vehicle routing problem. Moreover, an ant colony optimization algorithm is designed to solve stochastic time-dependent vehicle routing problem. As the improvements in initial solution and transition probability, ant colony optimization algorithm has a good performance in convergence. Through computational instances and Monte Carlo simulation tests, robust optimal schedule time model is proved to be better than minimum expected schedule time model in computational efficiency and coping with the travel time fluctuations. Therefore, robust optimal schedule time model is applicable in real road network.
An Artificial Bee Colony Algorithm for the Capacitated Vehicle Routing Problem
DEFF Research Database (Denmark)
Szeto, W.Y.; Wu, Yongzhong; Ho, Sin C.
This paper introduces an artificial bee colony heuristic for the capacitated vehicle routing problem. The artificial bee colony heuristic is a swarm-based heuristic, which mimics the foraging behavior of a honey bee swarm. The performance of the heuristic is evaluated on two sets of benchmark...
Single-Commodity Vehicle Routing Problem with Pickup and Delivery Service
Directory of Open Access Journals (Sweden)
Goran Martinovic
2008-01-01
Full Text Available We present a novel variation of the vehicle routing problem (VRP. Single commodity cargo with pickup and delivery service is considered. Customers are labeled as either cargo sink or cargo source, depending on their pickup or delivery demand. This problem is called a single commodity vehicle routing problem with pickup and delivery service (1-VRPPD. 1-VRPPD deals with multiple vehicles and is the same as the single-commodity traveling salesman problem (1-PDTSP when the number of vehicles is equal to 1. Since 1-VRPPD specializes VRP, it is hard in the strong sense. Iterative modified simulated annealing (IMSA is presented along with greedy random-based initial solution algorithm. IMSA provides a good approximation to the global optimum in a large search space. Experiment is done for the instances with different number of customers and their demands. With respect to average values of IMSA execution times, proposed method is appropriate for practical applications.
A framework for the interactive resolution of multi-objective vehicle routing problems
Geiger, Martin Josef
2008-01-01
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 windows, multiple depots, heterogeneous fleets, and, in particular, multiple optimization criteria. In order to identify a compromise alternative that meets the requirements of the decision maker, an interactive procedure is integrated in the resolution of the problem, allowing the modification of the preference information articulated by the decision maker. The framework is prototypically implemented in a computer system. First results of test runs on multiple depot vehicle routing problems with time windows are reported.
The Effects of the Tractor and Semitrailer Routing Problem on Mitigation of Carbon Dioxide Emissions
Directory of Open Access Journals (Sweden)
Hongqi Li
2013-01-01
Full Text Available The incorporation of CO2 emissions minimization in the vehicle routing problem (VRP is of critical importance to enterprise practice. Focusing on the tractor and semitrailer routing problem with full truckloads between any two terminals of the network, this paper proposes a mathematical programming model with the objective of minimizing CO2 emissions per ton-kilometer. A simulated annealing (SA algorithm is given to solve practical-scale problems. To evaluate the performance of the proposed algorithm, a lower bound is developed. Computational experiments on various problems generated randomly and a realistic instance are conducted. The results show that the proposed methods are effective and the algorithm can provide reasonable solutions within an acceptable computational time.
Solving the Tractor and Semi-Trailer Routing Problem Based on a Heuristic Approach
Directory of Open Access Journals (Sweden)
Hongqi Li
2012-01-01
Full Text Available We study the tractor and semi-trailer routing problem (TSRP, a variant of the vehicle routing problem (VRP. In the TSRP model for this paper, vehicles are dispatched on a trailer-flow network where there is only one main depot, and all tractors originate and terminate in the main depot. Two types of decisions are involved: the number of tractors and the route of each tractor. Heuristic algorithms have seen widespread application to various extensions of the VRP. However, this approach has not been applied to the TSRP. We propose a heuristic algorithm to solve the TSRP. The proposed heuristic algorithm first constructs the initial route set by the limitation of a driver’s on-duty time. The candidate routes in the initial set are then filtered by a two-phase approach. The computational study shows that our algorithm is feasible for the TSRP. Moreover, the algorithm takes relatively little time to obtain satisfactory solutions. The results suggest that our heuristic algorithm is competitive in solving the TSRP.
A new formulation for the 2-echelon capacitated vehicle routing problem
DEFF Research Database (Denmark)
Jepsen, Mads Kehlet; Røpke, Stefan; Spoorendonk, Simon
The 2-echelon capacitated vehicle routing problem (2E-CVRP) is a transportation and distribution problem where goods are transported from a depot to a set of customers possible via optional satellite facilities. The 2E-CVRP is relevant in city-logistic applications where legal restrictions make...... proposed for the previous formulations are redundant and that many model symmetries can now be avoided. A branch-and-cut algorithm is developed to solve this model to optimality....
Solving global two dimensional routing problems using Snell's law and A* search
Richbourg, Robert F.; Rowe, Neil C.; Zyda, Michael J.; McGhee, Robert
1986-01-01
Long range route planning based on map data is an important component in the intelligent control system of an autonomous agent. Most attempts to solve this problem rely on applying simple search strategies to high resolution, node and link representations of the map. These techniques have several disadvantages including large time and space requirements. The authors present a solution technique which utilizes a more intelligent representation of the problem environment. Topographical features...
GREEDY NON-DOMINATED SORTING IN GENETIC ALGORITHM-II FOR VEHICLE ROUTING PROBLEM IN DISTRIBUTION
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Vehicle routing problem in distribution (VRPD) is a widely used type of vehicle routing problem (VRP), which has been proved as NP-Hard, and it is usually modeled as single objective optimization problem when modeling. For multi-objective optimization model, most researches consider two objectives. A multi-objective mathematical model for VRP is proposed, which considers the number of vehicles used, the length of route and the time arrived at each client. Genetic algorithm is one of the most widely used algorithms to solve VRP. As a type of genetic algorithm (GA), non-dominated sorting in genetic algorithm-Ⅱ(NSGA-Ⅱ) also suffers from premature convergence and enclosure competition. In order to avoid these kinds of shortage, a greedy NSGA-Ⅱ (GNSGA-Ⅱ) is proposed for VRP problem. Greedy algorithm is implemented in generating the initial population, cross-over and mutation. All these procedures ensure that NSGA-Ⅱ is prevented from premature convergence and refine the performance of NSGA-Ⅱ at each step. In the distribution problem of a distribution center in Michigan, US, the GNSGA-Ⅱ is compared with NSGA-Ⅱ. As a result, the GNSGA-II is the most efficient one and can get the most optimized solution to VRP problem. Also, in GNSGA-II, premature convergence is better avoided and search efficiency has been improved sharply.
Directory of Open Access Journals (Sweden)
Martin Macík
2015-09-01
Full Text Available High level of competition on postal market increases demands on reliability of postal services and lowering of transport costs. This can be achieved by optimizing the routing of postal vehicles. The article discusses the possibilities of such optimization by using graph theory. It describes basic methods of finding optimal routes using a graph. The approach, used in this article, assesses the possibility of applying meta-heuristic solution to the traveling salesman problem in the postal sector. Simulation of methods described has been applied on a regional postal network. Results showed that the software used proves to be sufficiently functional for the field of postal transport networks.
The Electric Fleet Size and Mix Vehicle Routing Problem with Time Windows and Recharging Stations
DEFF Research Database (Denmark)
Hiermann, Gerhard; Puchinger, Jakob; Røpke, Stefan;
2016-01-01
detours to recharging stations necessary, thus requiring efficient tour planning mechanisms in order to sustain the competitiveness of electric vehicles compared to conventional vehicles. We introduce the Electric Fleet Size and Mix Vehicle Routing Problem with Time Windows and Recharging Stations (E......-FSMFTW) to model decisions to be made with regards to fleet composition and the actual vehicle routes including the choice of recharging times and locations. The available vehicle types differ in their transport capacity, battery size and acquisition cost. Furthermore, we consider time windows at customer...
A Mathematical Model for the Industrial Hazardous Waste Location-Routing Problem
Directory of Open Access Journals (Sweden)
Omid Boyer
2013-01-01
Full Text Available Technology progress is a cause of industrial hazardous wastes increasing in the whole world . Management of hazardous waste is a significant issue due to the imposed risk on environment and human life. This risk can be a result of location of undesirable facilities and also routing hazardous waste. In this paper a biobjective mixed integer programing model for location-routing industrial hazardous waste with two objectives is developed. First objective is total cost minimization including transportation cost, operation cost, initial investment cost, and cost saving from selling recycled waste. Second objective is minimization of transportation risk. Risk of population exposure within bandwidth along route is used to measure transportation risk. This model can help decision makers to locate treatment, recycling, and disposal centers simultaneously and also to route waste between these facilities considering risk and cost criteria. The results of the solved problem prove conflict between two objectives. Hence, it is possible to decrease the cost value by marginally increasing the transportation risk value and vice versa. A weighted sum method is utilized to combine two objectives function into one objective function. To solve the problem GAMS software with CPLEX solver is used. The problem is applied in Markazi province in Iran.
Optimized Crossover Genetic Algorithm for Vehicle Routing Problem with Time Windows
Directory of Open Access Journals (Sweden)
H. Nazif
2010-01-01
Full Text Available Problem statement: In this study, we considered the application of a genetic algorithm to vehicle routing problem with time windows where a set of vehicles with limits on capacity and travel time are available to service a set of customers with demands and earliest and latest time for serving. The objective is to find routes for the vehicles to service all the customers at a minimal cost without violating the capacity and travel time constraints of the vehicles and the time window constraints set by the customers. Approach: We proposed a genetic algorithm using an optimized crossover operator designed by a complete undirected bipartite graph that finds an optimal set of delivery routes satisfying the requirements and giving minimal total cost. Various techniques have also been introduced into the proposed algorithm to further enhance the solutions quality. Results: We tested our algorithm with benchmark instances and compared it with some other heuristics in the literature. The results showed that the proposed algorithm is competitive in terms of the quality of the solutions found. Conclusion/Recommendations: This study presented a genetic algorithm for solving vehicle routing problem with time windows using an optimized crossover operator. From the results, it can be concluded that the proposed algorithm is competitive when compared with other heuristics in the literature.
Vehicle Routing Problem for Fashion Supply Chains with Cross-Docking
Directory of Open Access Journals (Sweden)
Zhi-Hua Hu
2013-01-01
Full Text Available Cross-docking, as a strategy to reduce lead time and enhance the efficiency of the fashion supply chain, has attracted substantial attention from both the academy and the industry. Cross-docking is a critical part of many fashion and textiles supply chains in practice because it can help to achieve many supply chain strategies such as postponement. We consider a model where there are multiple suppliers and customers in a single cross-docking center. With such a model setting, the issue concerning the coordinated routing between the inbound and outbound routes is much more complex than many traditional vehicle routing problems (VRPs. We formulate the optimal route selection problems from the suppliers to the cross-docking center and from the cross-docking center to the customers as the respective VRPs. Based on the relationships between the suppliers and the customers, we integrate the two VRP models to optimize the overall traveling time, distance, and waiting time at the cross-docking center. In addition, we propose a novel mixed 0/1 integer linear programming model by which the complexity of the problem can be reduced significantly. As demonstrated by the simulation analysis, our proposed model can be solved very efficiently by a commonly used optimization software package.
Relative Performance of Certain Meta Heuristics on Vehicle Routing Problem with Time Windows
Directory of Open Access Journals (Sweden)
Sandhya
2015-11-01
Full Text Available —Solving Vehicle Routing Problem (VRP and its variants arise in many real life distribution systems. Classical VRP can be described as the problem of finding minimum cost routes with identical vehicles having fixed capacity which starts from a depot and reaches a number of customers with known demands with the proviso that each route starts and ends at the depot and the demand of each customer does not exceed the vehicle capacity is met. One of the generalizations of standard VRP is Vehicle Routing Problem with Time Windows (VRPTW with added complexity of serving every customer within a specified time window. Since VRPTW is a NP hard meta heuristics have often been designed for solving it. In this paper we compare the performance of Simulated Annealing (SA, genetic Algorithm (GA and Ant Colony Optimization (ACO for solving VRPTW based on their performance using different parameters taking total travel distance as the objective to be minimized. The results indicate that ACO is in general slightly more efficient then SA and GA.
Multiple Charging Station Location-Routing Problem with Time Window of Electric Vehicle
Directory of Open Access Journals (Sweden)
Wang Li-ying
2015-11-01
Full Text Available This paper presents the electric vehicle (EV multiple charging station location-routing problem with time window to optimize the routing plan of capacitated EVs and the strategy of charging stations. In particular, the strategy of charging stations includes both infrastructure-type selection and station location decisions. The problem accounts for two critical constraints in logistic practice: the vehicle loading capacity and the customer time windows. A hybrid heuristic that incorporates an adaptive variable neighborhood search (AVNS with the tabu search algorithm for intensification was developed to address the problem. The specialized neighborhood structures and the selection methods of charging station used in the shaking step of AVNS were proposed. In contrast to the commercial solver CPLEX, experimental results on small-scale test instances demonstrate that the algorithm can find nearly optimal solutions on small-scale instances. The results on large-scale instances also show the effectiveness of the algorithm.
A new memetic algorithm for solving split delivery vehicle routing problem
Directory of Open Access Journals (Sweden)
Ali Bozorgi-Amiri
2015-11-01
Full Text Available Split delivery vehicle routing problem is one of the traditional types of routing problems in which the demand of different points can be divided among vehicles and the objective is to minimize the path length, which vehicles travel. In this paper, fuel cost of vehicles which is assumed to be dependent on their traveled path and load is considered as the objective functions. Namely, the cost of the consumed fuel is proportionate to the unit of load carried per unit of distance. In order to solve the proposed model a new memetic algorithm is developed which has two rows. The performance of the proposed algorithm for 21 standard problems is compared with the optimum solutions obtained from mathematical programming standard solver and the solutions of the same algorithm with single row solution representation. The results express the efficiency of developed algorithm.
A Branch-and-Price Algorithm for Two Multi-Compartment Vehicle Routing Problems
DEFF Research Database (Denmark)
Mirzaei, Samira; Wøhlk, Sanne
2016-01-01
Despite the vast body of literature on vehicle routing problems, little attention has been paid to multi-compartment vehicle routing problems that investigate transportation of different commodities on the same vehicle, but in different compartments. In this project, we present two strategically...... different versions of the MCVRP in general settings. In the first version, different commodities may be delivered to the customer by different vehicles, but the full amount of each product must be delivered by a single vehicle. In the second version, each customer may only be serviced by a single vehicle......, which must deliver the full amount of all commodities demanded by that customer. We present a Branch-and-Price algorithm for solving the two versions of the problem to optimality and we analyze the effect of the strategic decision of whether or not to allow multiple visits to the same customer...
DEFF Research Database (Denmark)
Wen, Min; Krapper, Emil; Larsen, Jesper;
2011-01-01
The world's second largest producer of pork, Danish Crown, also provides a fresh meat supply logistics system within Denmark. This is used by the majority of supermarkets in Denmark. This article addresses an integrated vehicle routing and driver scheduling problem arising at Danish Crown....... The objective is to minimize the total delivery cost that is a weighted sum of two kinds of delivery costs. A multilevel variable neighborhood search heuristic is proposed for the problem. In a preprocessing step, the problem size is reduced through an aggregation procedure. Thereafter, the aggregated weekly...... planning problem is decomposed into daily planning problems, each of which is solved by a variable neighborhood search. Finally, the solution of the aggregated problem is expanded to that of the original problem. The method is implemented and tested on real‐life data consisting of up to 2,000 orders per...
Institute of Scientific and Technical Information of China (English)
Bin Jiang; Chao Yang; Takao Terano
2015-01-01
This paper proposes an adaptive agent model with a hybrid routing selection strategy for studying the road⁃network congestion problem. We focus on improving those severely congested links. Firstly, a multi⁃agent system is built, where each agent stands for a vehicle, and it makes its routing selection by considering the shortest path and the minimum congested degree of the target link simultaneously. The agent⁃based model captures the nonlinear feedback between vehicle routing behaviors and road⁃network congestion status. Secondly, a hybrid routing selection strategy is provided, which guides the vehicle routes adapting to the real⁃time road⁃network congestion status. On this basis, we execute simulation experiments and compare the simulation results of network congestion distribution, by Floyd agent with shortest path strategy and our proposed adaptive agent with hybrid strategy. The simulation results show that our proposed model has reduced the congestion degree of those seriously congested links of road⁃network. Finally, we execute our model on a real road map. The results finds that those seriously congested roads have some common features such as located at the road junction or near the unique road connecting two areas. And, the results also show an effectiveness of our model on reduction of those seriously congested links in this actual road network. Such a bottom⁃up congestion control approach with a hybrid congestion optimization perspective will have its significance for actual traffic congestion control.
A HYBRID GENETIC ALGORITHM IMPLEMENTATION FOR VEHICLE ROUTING PROBLEM WITH TIME WINDOWS
Directory of Open Access Journals (Sweden)
Muhammad Faisal Ibrahim
2016-01-01
Full Text Available This article is related to approach development in order to determine the most appropriate route for bottled water delivery from warehouse to retail from particular boundaries such as a limit on number of vehicle, vehicle capacity, and time windows to each retail. A mathematical model of VRPTW is adopted to solve the problem. Malang is one of the drinking water production centers in Indonesia, definitely it will be difficult for the company to determine the optimal delivery route with the existing restrictions. In this research hybrid genetic algorithm is use to determine the route shipping companies with the Java programming language. After analyzing the results obtained show that the results of the implementation of hybrid genetic algorithm is better than the company actual route. Moreover, authors also analyze the effect the number of iterations for the computation time, and the influence the number of iterations for the fitness value or violation. This algorithm can be applied for the routing and the result obtained is an optimal solution
A Location-Inventory-Routing Problem in Forward and Reverse Logistics Network Design
Directory of Open Access Journals (Sweden)
Qunli Yuchi
2016-01-01
Full Text Available We study a new problem of location-inventory-routing in forward and reverse logistic (LIRP-FRL network design, which simultaneously integrates the location decisions of distribution centers (DCs, the inventory policies of opened DCs, and the vehicle routing decision in serving customers, in which new goods are produced and damaged goods are repaired by a manufacturer and then returned to the market to satisfy customers’ demands as new ones. Our objective is to minimize the total costs of manufacturing and remanufacturing goods, building DCs, shipping goods (new or recovered between the manufacturer and opened DCs, and distributing new or recovered goods to customers and ordering and storage costs of goods. A nonlinear integer programming model is proposed to formulate the LIRP-FRL. A new tabu search (NTS algorithm is developed to achieve near optimal solution of the problem. Numerical experiments on the benchmark instances of a simplified version of the LIRP-FRL, the capacitated location routing problem, and the randomly generated LIRP-FRL instances demonstrate the effectiveness and efficiency of the proposed NTS algorithm in problem resolution.
Determination of optimal self-drive tourism route using the orienteering problem method
Hashim, Zakiah; Ismail, Wan Rosmanira; Ahmad, Norfaieqah
2013-04-01
This paper was conducted to determine the optimal travel routes for self-drive tourism based on the allocation of time and expense by maximizing the amount of attraction scores assigned to each city involved. Self-drive tourism represents a type of tourism where tourists hire or travel by their own vehicle. It only involves a tourist destination which can be linked with a network of roads. Normally, the traveling salesman problem (TSP) and multiple traveling salesman problems (MTSP) method were used in the minimization problem such as determination the shortest time or distance traveled. This paper involved an alternative approach for maximization method which is maximize the attraction scores and tested on tourism data for ten cities in Kedah. A set of priority scores are used to set the attraction score at each city. The classical approach of the orienteering problem was used to determine the optimal travel route. This approach is extended to the team orienteering problem and the two methods were compared. These two models have been solved by using LINGO12.0 software. The results indicate that the model involving the team orienteering problem provides a more appropriate solution compared to the orienteering problem model.
The Problems in QoS Routing%QoS中的路由问题
Institute of Scientific and Technical Information of China (English)
彭孜; 曾家智; 周明天
2000-01-01
The next-greneration high-speed networks are expected to suppot a wide range of delay-sensitive multimedia applications. They need a different routing algorithm from the conventional one. The goal of the new algorithm is twofold: (1)satisfying the QoS requirements for every admitted connections,and(2)achieving global efficiency in resource utilization. Thus,most of problems in QoS routing area have multiple constraints which make them NP-Hard. Until now,the generally effcient algorithm has not been found. In this paper,we pose two algorithms for PCPO problems common in QoS communication,and analyze respective characteristics and uses.
A variable neighborhood descent based heuristic to solve the capacitated location-routing problem
Directory of Open Access Journals (Sweden)
M. S. Jabal-Ameli
2011-01-01
Full Text Available Location-routing problem (LRP is established as a new research area in the context of location analysis. The primary concern of LRP is on locating facilities and routing of vehicles among established facilities and existing demand points. In this work, we address the capacitated LRP which arises in many practical applications within logistics and supply chain management. The objective is to minimize the overall system costs which include the fixed costs of opening depots and using vehicles at each depot site, and the variable costs associated with delivery activities. A novel heuristic is proposed which is based on variable neighborhood descent (VND algorithm to solve the resulted problem. The computational study indicates that the proposed VND based heuristic is highly competitive with the existing solution algorithms in terms of solution quality.
A Hybrid Genetic Algorithm for Vehicle Routing Problem with Complex Constraints
Institute of Scientific and Technical Information of China (English)
CHEN Yan; LU Jun; LI Zeng-zhi
2006-01-01
Most research on the Vehicle Routing Problem (VRP) is focused on standard conditions, which is not suitable for specific cases. A Hybrid Genetic Algorithm is proposed to solve a Vehicle Routing Problem (VRP) with complex side constraints. A novel coding method is designed especially for side constraints. A greedy algorithm combined with a random algorithm is introduced to enable the diversity of the initial population, as well as a local optimization algorithm employed to improve the searching efficiency. In order to evaluate the performance, this mechanism has been implemented in an oil distribution center, the experimental and executing results show that the near global optimal solution can be easily and quickly obtained by this method, and the solution is definitely satisfactory in the VRP application.
Li Liao; Jianfeng Li; Yaohua Wu
2013-01-01
Mathematical models of inventory-distribution routing problem for two-echelon agriculture products distribution network are established, which are based on two management modes, franchise chain and regular chain, one-to-many, interval periodic order, demand depending on inventory, deteriorating treatment cost of agriculture products, start-up costs of vehicles and so forth. Then, a heuristic adaptive genetic algorithm is presented for the model of franchise chain. For the regular chain model,...
Hossein Asefi; Samsung Lim; Mojtaba Maghrebi
2015-01-01
Municipal solid waste management is one of the challenging issues in mega cities due to various interrelated factors such as operational costs and environmental concerns. Cost as one of the most significant constraints of municipal solid waste management can be effectively economized by efficient planning approaches. Considering diverse waste types in an integrated municipal solid waste system, a mathematical model of the location-routing problem is formulated and solved in this study in orde...
The Electric Fleet Size and Mix Vehicle Routing Problem with Time Windows and Recharging Stations
Hiermann, Gerhard; Puchinger, Jakob; Ropke, Stefan; Hartl, Richard F.
2016-01-01
International audience Due to new regulations and further technological progress in the field of electric vehicles, the research community faces the new challenge of incorporating the electric energy based restrictions into vehicle routing problems. One of these restrictions is the limited battery capacity which makes detours to recharging stations necessary, thus requiring efficient tour planning mechanisms in order to sustain the competitiveness of electric vehicles compared to conventio...
Directory of Open Access Journals (Sweden)
Qi Hu
2013-04-01
Full Text Available State-of-the-art heuristic algorithms to solve the vehicle routing problem with time windows (VRPTW usually present slow speeds during the early iterations and easily fall into local optimal solutions. Focusing on solving the above problems, this paper analyzes the particle encoding and decoding strategy of the particle swarm optimization algorithm, the construction of the vehicle route and the judgment of the local optimal solution. Based on these, a hybrid chaos-particle swarm optimization algorithm (HPSO is proposed to solve VRPTW. The chaos algorithm is employed to re-initialize the particle swarm. An efficient insertion heuristic algorithm is also proposed to build the valid vehicle route in the particle decoding process. A particle swarm premature convergence judgment mechanism is formulated and combined with the chaos algorithm and Gaussian mutation into HPSO when the particle swarm falls into the local convergence. Extensive experiments are carried out to test the parameter settings in the insertion heuristic algorithm and to evaluate that they are corresponding to the data’s real-distribution in the concrete problem. It is also revealed that the HPSO achieves a better performance than the other state-of-the-art algorithms on solving VRPTW.
A new approach on auxiliary vehicle assignment in capacitated location routing problem
Bashiri, Mahdi; Rasoulinejad, Zeinab; Fallahzade, Ehsan
2016-03-01
The location routing problem (LRP) considers locating depots and vehicle routing decisions simultaneously. In classic LRP the number of customers in each route depends on the capacity of the vehicle. In this paper a capacitated LRP model with auxiliary vehicle assignment is presented in which the length of each route is not restricted by main vehicle capacity. Two kinds of vehicles are considered: main vehicles with higher capacity and fixed cost and auxiliary vehicles with lower capacity and fixed cost. The auxiliary vehicles can be added to the transportation system as an alternative strategy to cover the capacity limitations and they are just used to transfer goods from depots to vehicles and cannot serve the customers by themselves. To show the applicability of the proposed model, some numerical examples derived from the well-known instances are used. Moreover the model has been solved by some meta-heuristics for large sized instances. The results show the efficiency of the proposed model and the solution approach, considering the classic model and the exact solution approach, respectively.
A P-Based Hybrid Evolutionary Algorithm for Vehicle Routing Problem with Time Windows
Directory of Open Access Journals (Sweden)
Yunyun Niu
2014-01-01
Full Text Available The ability to solve optimization problems using membrane algorithms is an important application of membrane computing. This work combines membrane systems and genetic operators to build an approximated algorithm for the vehicle routing problem with time windows. The algorithm is based on a tissue-like membrane structure combined with cell separation rules and communication rules; during such processes membranes collect and disperse information. Genetic operators are used as the system's subalgorithms. We also design a special improvement strategy to speed up the search process in subsystems. The experimental results show that the solution quality from the proposed algorithm is competitive with other heuristic or metaheuristic algorithms in the literature.
A branch-and-cut algorithm for the symmetric two-echelon capacitated vehicle routing problem
DEFF Research Database (Denmark)
Jepsen, Mads Kehlet; Spoorendonk, Simon; Røpke, Stefan
2013-01-01
This paper presents an exact method for solving the symmetric two-echelon capacitated vehicle routing problem, a transportation problem concerned with the distribution of goods from a depot to a set of customers through a set of satellite locations. The presented method is based on an edge flow...... model that is a relaxation and provides a valid lower bound. A specialized branching scheme is employed to obtain feasible solutions. Out of a test set of 93 instances the algorithm is able to solve 47 to optimality surpassing previous exact algorithms....
Clique inequalities applied to the vehicle routing problem with time windows
DEFF Research Database (Denmark)
Spoorendonk, Simon; Desaulniers, Guy
2010-01-01
This work presents an exact branch-cut-and-price algorithm for the vehicle routing problem with time windows (VRPTW) where the well-known clique inequalities are used as cutting planes defined on the set partitioning master problem variables. It shows how these cutting planes affect the dominance......, to our knowledge, this is a first attempt at incorporating for the VRPTW a set of valid inequalities specialized for the set partitioning polytope. Computational results show that the use of clique inequalities improves the lower bound at the root node of the search tree and reduces the number of...
A Column Generation Approach to the Capacitated Vehicle Routing Problem with Stochastic Demands
DEFF Research Database (Denmark)
Christiansen, Christian Holk; Lysgaard, Jens
In this article we introduce a new exact solution approach to the Capacitated Vehicle Routing Problem with Stochastic Demands (CVRPSD). In particular, we consider the case where all customer demands are distributed independently and where each customer's demand follows a Poisson distribution....... The CVRPSD can be formulated as a Set Partitioning Problem. We show that, under the above assumptions on demands, the associated column generation subproblem can be solved using a dynamic programming scheme which is similar to that used in the case of deterministic demands. To evaluate the potential of our...
Directory of Open Access Journals (Sweden)
Yan Sun
2015-09-01
Full Text Available Purpose: The purpose of study is to solve the multi-modal transportation routing planning problem that aims to select an optimal route to move a consignment of goods from its origin to its destination through the multi-modal transportation network. And the optimization is from two viewpoints including cost and time. Design/methodology/approach: In this study, a bi-objective mixed integer linear programming model is proposed to optimize the multi-modal transportation routing planning problem. Minimizing the total transportation cost and the total transportation time are set as the optimization objectives of the model. In order to balance the benefit between the two objectives, Pareto optimality is utilized to solve the model by gaining its Pareto frontier. The Pareto frontier of the model can provide the multi-modal transportation operator (MTO and customers with better decision support and it is gained by the normalized normal constraint method. Then, an experimental case study is designed to verify the feasibility of the model and Pareto optimality by using the mathematical programming software Lingo. Finally, the sensitivity analysis of the demand and supply in the multi-modal transportation organization is performed based on the designed case. Findings: The calculation results indicate that the proposed model and Pareto optimality have good performance in dealing with the bi-objective optimization. The sensitivity analysis also shows the influence of the variation of the demand and supply on the multi-modal transportation organization clearly. Therefore, this method can be further promoted to the practice. Originality/value: A bi-objective mixed integer linear programming model is proposed to optimize the multi-modal transportation routing planning problem. The Pareto frontier based sensitivity analysis of the demand and supply in the multi-modal transportation organization is performed based on the designed case.
A modified ant colony optimization to solve multi products inventory routing problem
Wong, Lily; Moin, Noor Hasnah
2014-07-01
This study considers a one-to-many inventory routing problem (IRP) network consisting of a manufacturer that produces multi products to be transported to many geographically dispersed customers. We consider a finite horizon where a fleet of capacitated homogeneous vehicles, housed at a depot/warehouse, transport products from the warehouse to meet the demand specified by the customers in each period. The demand for each product is deterministic and time varying and each customer requests a distinct product. The inventory holding cost is product specific and is incurred at the customer sites. The objective is to determine the amount on inventory and to construct a delivery schedule that minimizes both the total transportation and inventory holding costs while ensuring each customer's demand is met over the planning horizon. The problem is formulated as a mixed integer programming problem and is solved using CPLEX 12.4 to get the lower and upper bound (best integer solution) for each problem considered. We propose a modified ant colony optimization (ACO) to solve the problem and the built route is improved by using local search. ACO performs better on large instances compared to the upper bound.
A Hybrid Column Generation approach for an Industrial Waste Collection Routing Problem
DEFF Research Database (Denmark)
Hauge, Kristian; Larsen, Jesper; Lusby, Richard Martin;
2014-01-01
This paper presents a practical roll-on/roll-o_ routing (ROROR) problem arising in the collection of industrial waste. Skip containers, which are used for the waste col-lection, need to be distributed between, and collected from, a set of customers. Full containers must be driven to dump sites...... two of which can be full. We propose a Generalized Set Partitioning formulation of the problem and describe a hybrid column generation procedure to solve it. A fast Tabu Search heuristic is used to generate new columns. The proposed methodology is tested on nine data sets, four of which are actual......, real-world problem instances. Results indicate that the hybrid column generation outperforms a purely heuristic approach in terms of both running time and solution quality. High quality solutions to problems containing up to 100 orders can be solved in approximately 15 minutes....
A STUDY AND IMPLEMENTATION OF THE TRANSIT ROUTE NETWORK DESIGN PROBLEM FOR A REALISTIC URBAN CASE
Directory of Open Access Journals (Sweden)
M. Kalochristianakis
2016-01-01
Full Text Available The design of public transportation networks presupposes solving optimization problems, involving various parameters such as the proper mathematical description of networks, the algorithmic approach to apply, and also the consideration of real-world, practical characteristics such as the types of vehicles in the network, the frequencies of routes, demand, possible limitations of route capacities, travel decisions made by passengers, the environmental footprint of the system, the available bus technologies, besides others. The current paper presents the progress of the work that aims to study the design of a municipal public transportation system that employs middleware technologies and geographic information services in order to produce practical, realistic results. The system employs novel optimization approaches such as the particle swarm algorithms and also considers various environmental parameters such as the use of electric vehicles and the emissions of conventional ones.
Intelligent Iterated Local Search Methods for Solving Vehicle Routing Problem with Different Fleets
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
To solve vehicle routing problem with different fleets, two methodologies are developed. The first methodology adopts twophase strategy. In the first phase, the improved savings method is used to assign customers to appropriate vehicles. In the second phase, the iterated dynasearch algorithm is adopted to route each selected vehicle with the assigned customers. The iterated dynasearch algorithm combines dynasearch algorithm with iterated local search algorithm based on random kicks. The second methodplogy adopts the idea of cyclic transfer which is performed by using dynamic programming algorithm, and the iterated dynasearch algorithm is also embedded in it. The test results show that both methodologies generate better solutions than the traditional method, and the second methodology is superior to the first one.
A location-routing problem model with multiple periods and fuzzy demands
Directory of Open Access Journals (Sweden)
Ali Nadizadeh
2014-08-01
Full Text Available This paper puts forward a dynamic capacitated location-routing problem with fuzzy demands (DCLRP-FD. It is given on input a set of identical vehicles (each having a capacity, a fixed cost and availability level, a set of depots with restricted capacities and opening costs, a set of customers with fuzzy demands, and a planning horizon with multiple periods. The problem consists of determining the depots to be opened only in the first period of the planning horizon, the customers and the vehicles to be assigned to each opened depot, and performing the routes that may be changed in each time period due to fuzzy demands. A fuzzy chance-constrained programming (FCCP model has been designed using credibility theory and a hybrid heuristic algorithm with four phases is presented in order to solve the problem. To obtain the best value of the fuzzy parameters of the model and show the influence of the availability level of vehicles on final solution, some computational experiments are carried out. The validity of the model is then evaluated in contrast with CLRP-FD's models in the literature. The results indicate that the model and the proposed algorithm are robust and could be used in real world problems.
A two-stage heuristic method for vehicle routing problem with split deliveries and pickups
Institute of Scientific and Technical Information of China (English)
Yong WANG; Xiao-lei MA; Yun-teng LAO; Hai-yan YU; Yong LIU
2014-01-01
The vehicle routing problem (VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the restricted conditions of traditional VRP has become a research focus in the past few decades. The vehicle routing problem with split deliveries and pickups (VRPSPDP) is particularly proposed to release the constraints on the visiting times per customer and vehicle capacity, that is, to allow the deliveries and pickups for each customer to be simultaneously split more than once. Few studies have focused on the VRPSPDP problem. In this paper we propose a two-stage heuristic method integrating the initial heuristic algorithm and hybrid heuristic algorithm to study the VRPSPDP problem. To validate the proposed algorithm, Solomon benchmark datasets and extended Solomon benchmark datasets were modified to compare with three other popular algorithms. A total of 18 datasets were used to evaluate the effectiveness of the proposed method. The computational results indicated that the proposed algorithm is superior to these three algorithms for VRPSPDP in terms of total travel cost and average loading rate.
Metaheuristics for multi products inventory routing problem with time varying demand
Moin, Noor Hasnah; Ab Halim, Huda Zuhrah; Yuliana, Titi
2014-07-01
This paper addresses the inventory routing problem (IRP) with a many-to-one distribution network, consisting of a single depot, an assembly plant, and geographically dispersed suppliers where a capacitated homogeneous vehicle delivers a distinct product from the suppliers to fulfill the demand specified by the assembly plant over the planning horizon. The inventory holding cost is assumed to be product specific and only incurred at the assembly plant. Two metaheuristics comprise of artificial bee colony (ABC) and scatter search (SS) algorithms are proposed to solve the problem. Computational testing on instances which represents small, medium, and large data sets show that the ABC algorithm performs slightly better when compared the SS overall except for fifty suppliers problems.
A memory structure adapted simulated annealing algorithm for a green vehicle routing problem.
Küçükoğlu, İlker; Ene, Seval; Aksoy, Aslı; Öztürk, Nursel
2015-03-01
Currently, reduction of carbon dioxide (CO2) emissions and fuel consumption has become a critical environmental problem and has attracted the attention of both academia and the industrial sector. Government regulations and customer demands are making environmental responsibility an increasingly important factor in overall supply chain operations. Within these operations, transportation has the most hazardous effects on the environment, i.e., CO2 emissions, fuel consumption, noise and toxic effects on the ecosystem. This study aims to construct vehicle routes with time windows that minimize the total fuel consumption and CO2 emissions. The green vehicle routing problem with time windows (G-VRPTW) is formulated using a mixed integer linear programming model. A memory structure adapted simulated annealing (MSA-SA) meta-heuristic algorithm is constructed due to the high complexity of the proposed problem and long solution times for practical applications. The proposed models are integrated with a fuel consumption and CO2 emissions calculation algorithm that considers the vehicle technical specifications, vehicle load, and transportation distance in a green supply chain environment. The proposed models are validated using well-known instances with different numbers of customers. The computational results indicate that the MSA-SA heuristic is capable of obtaining good G-VRPTW solutions within a reasonable amount of time by providing reductions in fuel consumption and CO2 emissions. PMID:25056743
A Framing Link Based Tabu Search Algorithm for Large-Scale Multidepot Vehicle Routing Problems
Directory of Open Access Journals (Sweden)
Xuhao Zhang
2014-01-01
Full Text Available A framing link (FL based tabu search algorithm is proposed in this paper for a large-scale multidepot vehicle routing problem (LSMDVRP. Framing links are generated during continuous great optimization of current solutions and then taken as skeletons so as to improve optimal seeking ability, speed up the process of optimization, and obtain better results. Based on the comparison between pre- and postmutation routes in the current solution, different parts are extracted. In the current optimization period, links involved in the optimal solution are regarded as candidates to the FL base. Multiple optimization periods exist in the whole algorithm, and there are several potential FLs in each period. If the update condition is satisfied, the FL base is updated, new FLs are added into the current route, and the next period starts. Through adjusting the borderline of multidepot sharing area with dynamic parameters, the authors define candidate selection principles for three kinds of customer connections, respectively. Link split and the roulette approach are employed to choose FLs. 18 LSMDVRP instances in three groups are studied and new optimal solution values for nine of them are obtained, with higher computation speed and reliability.
An artificial bee colony algorithm for the capacitated vehicle routing problem
DEFF Research Database (Denmark)
Szeto, W.Y.; Wu, Yongzhong; Ho, Sin C.
2011-01-01
This paper introduces an artificial bee colony heuristic for solving the capacitated vehicle routing problem. The artificial bee colony heuristic is a swarm-based heuristic, which mimics the foraging behavior of a honey bee swarm. An enhanced version of the artificial bee colony heuristic is also...... proposed to improve the solution quality of the original version. The performance of the enhanced heuristic is evaluated on two sets of standard benchmark instances, and compared with the original artificial bee colony heuristic. The computational results show that the enhanced heuristic outperforms...
Directory of Open Access Journals (Sweden)
Hossein Asefi
2015-09-01
Full Text Available Municipal solid waste management is one of the challenging issues in mega cities due to various interrelated factors such as operational costs and environmental concerns. Cost as one of the most significant constraints of municipal solid waste management can be effectively economized by efficient planning approaches. Considering diverse waste types in an integrated municipal solid waste system, a mathematical model of the location-routing problem is formulated and solved in this study in order to minimize the total cost of transportation and facility establishment.
Energy Technology Data Exchange (ETDEWEB)
Moeini, R.; Afshar, M.H.
2011-07-15
Hydropower is currently the number one source of electricity production in the world. For the design and construction of such systems, mathematical modelling is often use for reservoir operations. As conventional methods present some shortcomings in solving reservoir operation problems, a new method is presented here. It consists in an arc-based formulation of hydropower reservoir operation problems which can be applied to ant colony optimization algorithms. This paper first described this formulation and then applied it to solve two hydropower reservoir operation problems. The results showed that this formulation can optimally solve large-scale hydropower reservoir operation problems while offering a clear definition of heuristic information.
Directory of Open Access Journals (Sweden)
Subbaraj Potti
2011-01-01
Full Text Available Problem statement: A new multi-objective approach, Strength Pareto Evolutionary Algorithm (SPEA, is presented in this paper to solve the shortest path routing problem. The routing problem is formulated as a multi-objective mathematical programming problem which attempts to minimize both cost and delay objectives simultaneously. Approach: SPEA handles the shortest path routing problem as a true multi-objective optimization problem with competing and noncommensurable objectives. Results: SPEA combines several features of previous multi-objective evolutionary algorithms in a unique manner. SPEA stores nondominated solutions externally in another continuously-updated population and uses a hierarchical clustering algorithm to provide the decision maker with a manageable pareto-optimal set. SPEA is applied to a 20 node network as well as to large size networks ranging from 50-200 nodes. Conclusion: The results demonstrate the capabilities of the proposed approach to generate true and well distributed pareto-optimal nondominated solutions.
A new algorithm for solving the inventory routing problem with direct shipment
Directory of Open Access Journals (Sweden)
Ali Hossein Mirzaei
2012-02-01
Full Text Available In this paper a multi-commodity multi-period inventory routing problem in a two-echelon supply chain consisting of a manufacturer and a set of retailers has been studied. In addition to inventory management and distribution planning, production planning has also been considered in the above problem. The objective is to minimize total system cost that consists of production setup, inventory holding and distribution costs. The commodities are delivered to the retailers by an identical fleet of limited capacity vehicles through direct shipment strategy. Also it is assumed that production and storage capacity is limited and stockout is not allowed. Since similar problems without distribution planning are known as NP-hard, this is also an NP-hard problem. Therefore, in this paper, a new improved particle swarm optimization algorithm has been developed consisting of two distinguished phases for problem solving. First, the values of binary variables are determined using the proposed algorithm and then, the continuous variables are calculated by solving a linear programming model. Performance of the proposed algorithm has been compared with genetic and original particle swarm optimization algorithms using various samples of random problems. The findings imply significant performance of the proposed algorithm.
Modified artificial bee colony for the vehicle routing problems with time windows.
Alzaqebah, Malek; Abdullah, Salwani; Jawarneh, Sana
2016-01-01
The natural behaviour of the honeybee has attracted the attention of researchers in recent years and several algorithms have been developed that mimic swarm behaviour to solve optimisation problems. This paper introduces an artificial bee colony (ABC) algorithm for the vehicle routing problem with time windows (VRPTW). A Modified ABC algorithm is proposed to improve the solution quality of the original ABC. The high exploration ability of the ABC slows-down its convergence speed, which may due to the mechanism used by scout bees in replacing abandoned (unimproved) solutions with new ones. In the Modified ABC a list of abandoned solutions is used by the scout bees to memorise the abandoned solutions, then the scout bees select a solution from the list based on roulette wheel selection and replace by a new solution with random routs selected from the best solution. The performance of the Modified ABC is evaluated on Solomon benchmark datasets and compared with the original ABC. The computational results demonstrate that the Modified ABC outperforms the original ABC also produce good solutions when compared with the best-known results in the literature. Computational investigations show that the proposed algorithm is a good and promising approach for the VRPTW. PMID:27547672
Chen, Xianshun; Feng, Liang; Ong, Yew Soon
2012-07-01
In this article, we proposed a self-adaptive memeplex robust search (SAMRS) for finding robust and reliable solutions that are less sensitive to stochastic behaviours of customer demands and have low probability of route failures, respectively, in vehicle routing problem with stochastic demands (VRPSD). In particular, the contribution of this article is three-fold. First, the proposed SAMRS employs the robust solution search scheme (RS 3) as an approximation of the computationally intensive Monte Carlo simulation, thus reducing the computation cost of fitness evaluation in VRPSD, while directing the search towards robust and reliable solutions. Furthermore, a self-adaptive individual learning based on the conceptual modelling of memeplex is introduced in the SAMRS. Finally, SAMRS incorporates a gene-meme co-evolution model with genetic and memetic representation to effectively manage the search for solutions in VRPSD. Extensive experimental results are then presented for benchmark problems to demonstrate that the proposed SAMRS serves as an efficable means of generating high-quality robust and reliable solutions in VRPSD.
Directory of Open Access Journals (Sweden)
Zheng Wang
2013-01-01
Full Text Available This paper presents a flexible solution methodology for the capacitated vehicle routing problem with stochastic travel times (CVRPSTT. One of the basic ideas of the methodology is to consider a vehicle working time lower than the actual maximum vehicle working time when designing CVRPSTT solutions. In this way, the working time surplus can be used to cope with unexpected congestions when necessary. Another important idea is to transform the CVRPSTT instance to a limited set of capacitated vehicle routing problems (CVRP, each of which is defined by a given percentage of the maximum vehicle working time. Thus, our approach can take advantage of any efficient heuristic that already exists for the CVRP. Based on the two key ideas, this paper presents a simulation-based algorithm, in which Monte Carlo simulation is used to obtain estimates of the cost and the reliability of each solution, and the Clarke and Wright heuristic is improved to generate more reliable solutions. Finally, a number of numerical experiments are done in the paper with the purpose of analyzing the efficiency of the described methodology under different uncertainty scenarios.
The Edge Set Cost of the Vehicle Routing Problem with Time Windows
DEFF Research Database (Denmark)
Reinhardt, Line Blander; Jepsen, Mads Kehlet; Pisinger, David
2016-01-01
We consider an important generalization of the vehicle routing problem with time windows in which a fixed cost must be paid for accessing a set of edges. This fixed cost could reflect payment for toll roads, investment in new facilities, the need for certifications, and other costly investments....... The certifications and investments impose a cost for the company while they also give unlimited usage of a set of roads to all vehicles belonging to the company. This violates the traditional assumption that the path between two destinations is well defined and independent of other choices. Different versions...... for defining the edge sets are discussed and formulated. Both the multigraph case and the direct path case are described, and mixed-integer-programming formulations of the problem are presented for both cases. A solution method based on branch-price-and-cut is applied to the direct path case. The computational...
Research on cultural algorithm for solving routing problem of mobile agent
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
The key idea behind cultural algorithm is to explicitly acquire problem-solving knowledge from the evolving population and in return apply that knowledge to guide the search. In this article, cultural algorithm-simulated annealing is proposed to solve the routing problem of mobile agent. The optimal individual is accepted to improve the belief space's evolution of cultural algorithms by simulated annealing. The step size in search is used as situational knowledge to guide the search of optimal solution in the population space. Because of this feature, the search time is reduced. Experimental results show that the algorithm proposed in this article can ensure the quality of optimal solutions, and also has better convergence speed. The operation efficiency of the system is considerably improved.
Application of Modified Ant Colony Optimization (MACO for Multicast Routing Problem
Directory of Open Access Journals (Sweden)
Sudip Kumar Sahana
2016-04-01
Full Text Available It is well known that multicast routing is combinatorial problem finds the optimal path between source destination pairs. Traditional approaches solve this problem by establishment of the spanning tree for the network which is mapped as an undirected weighted graph. This paper proposes a Modified Ant Colony Optimization (MACO algorithm which is based on Ant Colony System (ACS with some modification in the configuration of starting movement and in local updation technique to overcome the basic limitations of ACS such as poor initialization and slow convergence rate. It is shown that the proposed Modified Ant Colony Optimization (MACO shows better convergence speed and consumes less time than the conventional ACS to achieve the desired solution.
Directory of Open Access Journals (Sweden)
Omprakash Kaiwartya
2015-01-01
Full Text Available A multiobjective dynamic vehicle routing problem (M-DVRP has been identified and a time seed based solution using particle swarm optimization (TS-PSO for M-DVRP has been proposed. M-DVRP considers five objectives, namely, geographical ranking of the request, customer ranking, service time, expected reachability time, and satisfaction level of the customers. The multiobjective function of M-DVRP has four components, namely, number of vehicles, expected reachability time, and profit and satisfaction level. Three constraints of the objective function are vehicle, capacity, and reachability. In TS-PSO, first of all, the problem is partitioned into smaller size DVRPs. Secondly, the time horizon of each smaller size DVRP is divided into time seeds and the problem is solved in each time seed using particle swarm optimization. The proposed solution has been simulated in ns-2 considering real road network of New Delhi, India, and results are compared with those obtained from genetic algorithm (GA simulations. The comparison confirms that TS-PSO optimizes the multiobjective function of the identified problem better than what is offered by GA solution.
Baron, Danielle M; Ramirez, Alejandro J; Bulitko, Vadim; Madan, Christopher R; Greiner, Ariel; Hurd, Peter L; Spetch, Marcia L
2015-01-01
Visiting multiple locations and returning to the start via the shortest route, referred to as the traveling salesman (or salesperson) problem (TSP), is a valuable skill for both humans and non-humans. In the current study, pigeons were trained with increasing set sizes of up to six goals, with each set size presented in three distinct configurations, until consistency in route selection emerged. After training at each set size, the pigeons were tested with two novel configurations. All pigeons acquired routes that were significantly more efficient (i.e., shorter in length) than expected by chance selection of the goals. On average, the pigeons also selected routes that were more efficient than expected based on a local nearest-neighbor strategy and were as efficient as the average route generated by a crossing-avoidance strategy. Analysis of the routes taken indicated that they conformed to both a nearest-neighbor and a crossing-avoidance strategy significantly more often than expected by chance. Both the time taken to visit all goals and the actual distance traveled decreased from the first to the last trials of training in each set size. On the first trial with novel configurations, average efficiency was higher than chance, but was not higher than expected from a nearest-neighbor or crossing-avoidance strategy. These results indicate that pigeons can learn to select efficient routes on a TSP problem.
Hao Yu; Wei Deng Solvang
2016-01-01
Hazardous waste location-routing problems are of importance due to the potential risk for nearby residents and the environment. In this paper, an improved mathematical formulation is developed based upon a multi-objective mixed integer programming approach. The model aims at assisting decision makers in selecting locations for different facilities including treatment plants, recycling plants and disposal sites, providing appropriate technologies for hazardous waste treatment, and routing tran...
Improved Multi-Agent System for the Vehicle Routing Problem with Time Windows
Institute of Scientific and Technical Information of China (English)
DAN Zhenggang; CAI Linning; ZHENG Li
2009-01-01
The vehicle routing problem with time windows (VRPTW) involves assigning a fleet of limited ca-pacity vehicles to serve a set of customers without violating the capacity and time constraints. This paper presents a multi-agent model system for the VRPTW based on the internal behavior of agents and coordina-tion among the agents. The system presents a formal view of coordination using the traditional contract-net protocol (CNP) that relies on the basic loop of agent behavior for order receiving, order announcement, bid calculation, and order scheduling followed by order execution. An improved CNP method based on a vehicle selection strategy is used to reduce the number of negotiations and the negotiation time. The model is vali-dated using Solomon's benchmarks, with the results showing that the improved CNP uses only 30% as many negotiations and only 70% of the negotiation time of the traditional CNP.
A hybrid genetic algorithm for route optimization in the bale collecting problem
Directory of Open Access Journals (Sweden)
C. Gracia
2013-06-01
Full Text Available The bale collecting problem (BCP appears after harvest operations in grain and other crops. Its solution defines the sequence of collecting bales which lie scattered over the field. Current technology on navigation-aid systems or auto-steering for agricultural vehicles and machines, is able to provide accurate data to make a reliable bale collecting planning. This paper presents a hybrid genetic algorithm (HGA approach to address the BCP pursuing resource optimization such as minimizing non-productive time, fuel consumption, or distance travelled. The algorithmic route generation provides the basis for a navigation tool dedicated to loaders and bale wagons. The approach is experimentally tested on a set of instances similar to those found in real situations. In particular, comparative results show an average improving of a 16% from those obtained by previous heuristics.
Hays, Graeme C; Christensen, Asbjørn; Fossette, Sabrina; Schofield, Gail; Talbot, Julian; Mariani, Patrizio
2014-02-01
The optimum path to follow when subjected to cross flows was first considered over 80 years ago by the German mathematician Ernst Zermelo, in the context of a boat being displaced by ocean currents, and has become known as the 'Zermelo navigation problem'. However, the ability of migrating animals to solve this problem has received limited consideration, even though wind and ocean currents cause the lateral displacement of flyers and swimmers, respectively, particularly during long-distance journeys of 1000s of kilometres. Here, we examine this problem by combining long-distance, open-ocean marine turtle movements (obtained via long-term GPS tracking of sea turtles moving 1000s of km), with a high resolution basin-wide physical ocean model to estimate ocean currents. We provide a robust mathematical framework to demonstrate that, while turtles eventually arrive at their target site, they do not follow the optimum (Zermelo's) route. Even though adult marine turtles regularly complete incredible long-distance migrations, these vertebrates primarily rely on course corrections when entering neritic waters during the final stages of migration. Our work introduces a new perspective in the analysis of wildlife tracking datasets, with different animal groups potentially exhibiting different levels of complexity in goal attainment during migration. PMID:24304813
A Memetic Algorithm for the Vehicle Routing Problem with Cross Docking
Directory of Open Access Journals (Sweden)
Sanae Larioui
2015-11-01
Full Text Available In this paper we address the VRPCD, in which a set of homogeneous vehicles are used to transport products from the suppliers to customers via a cross-dock. The products can be consolidated at the cross-dock but cannot be stored for very long as the cross-dock does not have long-term inventory-holding capabilities. The objective of the VRPCD is to minimize the total traveled distance while respecting time window constraints of suppliers and customers and a time horizon for the whole transportation operation. Rummaging through all the work of literature on vehicle routing problems with cross-docking, there is no work that considers that customer will receive its requests from several suppliers; this will be the point of innovation of this work. A heuristic and a memetic algorithm are used to solve the problem. The proposed algorithms are implemented and tested on data sets involving up to 200 nodes (customers and suppliers. The first results show that the memetic algorithm can produce high quality solutions.
Directory of Open Access Journals (Sweden)
Wan-Yu Liu
2014-07-01
Full Text Available Torespondto the reduction of greenhouse gas emissions and global warming, this paper investigates the minimal-carbon-footprint time-dependent heterogeneous-fleet vehicle routing problem with alternative paths (MTHVRPP. This finds a route with the smallestcarbon footprint, instead of the shortestroute distance, which is the conventional approach, to serve a number of customers with a heterogeneous fleet of vehicles in cases wherethere may not be only one path between each pair of customers, and the vehicle speed differs at different times of the day. Inheriting from the NP-hardness of the vehicle routing problem, the MTHVRPP is also NP-hard. This paper further proposes a genetic algorithm (GA to solve this problem. The solution representedbyour GA determines the customer serving ordering of each vehicle type. Then, the capacity check is used to classify multiple routes of each vehicle type, and the path selection determines the detailed paths of each route. Additionally, this paper improves the energy consumption model used for calculating the carbon footprint amount more precisely. Compared with the results without alternative paths, our experimental results show that the alternative path in this experimenthas a significant impact on the experimental results in terms of carbon footprint.
Directory of Open Access Journals (Sweden)
Masoud Rabbani
2013-09-01
Full Text Available Integration of various logistical components in supply chain management, such as transportation, inventory control and facility location are becoming common practice to avoid sub-optimization in nowadays’ competitive environment. The integration of transportation and inventory decisions is known as inventory routing problem (IRP in the literature. The problem aims to determine the delivery quantity for each customer and the network routes to be used in each period, so that the total inventory and transportation costs are to be minimized. On the contrary of conventional IRP that each retailer can only provide its demand from the supplier, in this paper, a new multi-period, multi-item IRP model with considering lateral trans-shipment, back-log and financial decisions is proposed as a business model in a distinct organization. The main purpose of this paper is applying an applicable inventory routing model with considering real world setting and solving it with an appropriate method.
MILP for the Inventory and Routing for Replenishment Problem in the Car Assembly Line.
Directory of Open Access Journals (Sweden)
Raul Pulido
2014-01-01
Full Text Available The inbound logistic for feeding the workstation inside the factory represents a critical issue in the car manufacturing industry. Nowadays, this issue is even more critical than in the past since more types of car are being produced in the assembly lines. Consequently, as workstations have to install many types of components, they also need to have an inventory of different types of the component in a compact space.The replenishment is a critical issue since a lack of inventory could cause line stoppage or reworking. On the other hand, an excess of inventory could increase the holding cost or even block the replenishment paths. The decision of the replenishment routes cannot be made without taking into consideration the inventory needed by each station during the production time which will depend on the production sequence. This problem deals with medium-sized instances and it is solved using online solvers. The contribution of this paper is a MILP for the replenishment and inventory of the components in a car assembly line.
Approximation Algorithms and Hardness of the k-Route Cut Problem
Chuzhoy, Julia; Zhou, Yuan; Vijayaraghavan, Aravindan
2011-01-01
We study the k-route cut problem: given an undirected edge-weighted graph G=(V,E), a collection {(s_1,t_1),(s_2,t_2),...,(s_r,t_r)} of source-sink pairs, and an integer connectivity requirement k, the goal is to find a minimum-weight subset E' of edges to remove, such that the connectivity of every pair (s_i, t_i) falls below k. Specifically, in the edge-connectivity version, EC-kRC, the requirement is that there are at most (k-1) edge-disjoint paths connecting s_i to t_i in G \\ E', while in the vertex-connectivity version, NC-kRC, the same requirement is for vertex-disjoint paths. Prior to our work, poly-logarithmic approximation algorithms have been known for the special case where k >= 3, but no non-trivial approximation algorithms were known for any value k>3, except in the single-source setting. We show an O(k log^{3/2}r)-approximation algorithm for EC-kRC with uniform edge weights, and several polylogarithmic bi-criteria approximation algorithms for EC-kRC and NC-kRC, where the connectivity requirement ...
Directory of Open Access Journals (Sweden)
Alberto Ochoa-Ortíz
2015-01-01
Full Text Available El problema de ruteo de vehículos bajo las limitaciones de capacidad y basado en computación ubicua desde una perspectiva relacionada con PSS (Producto-Servicio de Sistemas para desarrollar configuraciones para el transporte urbano de mercancías es abordado. Éste trabajo considera las especificidades de la logística urbana bajo un contexto de mercados emergentes. En este caso, involucra: i bajas competencias logísticas de los tomadores de decisiones; ii la limitada disponibilidad de datos; y iii restringido acceso a tecnología de alto desempeño para calcular rutas de transporte óptimas. Por lo tanto, se propone el uso de un software libre que proporciona soluciones de bajo costo (en tiempo y recursos. El artículo muestra la aplicación de los resultados de una herramienta de software basado en la Teoría de Grafos utilizado para analizar y resolver un CVRP (Capacitated Vehicle Routing Problem. Se utilizó el caso de una empresa local de distribución de alimentos situada en una gran ciudad de México. Sobre la base de una flora de vehículos pequeños, todos con las mismas especificaciones técnicas y una capacidad de carga comparable.
An optimization algorithm for a capacitated vehicle routing problem with time windows
Indian Academy of Sciences (India)
PINAR KIRCI
2016-05-01
In this paper, vehicle routing problem (VRP) with time windows and real world constraints are considered as a real-world application on google maps. Also, tabu search is used and Hopfield neural networks is utilized. Basic constraints consist of customer demands, time windows, vehicle speed, vehicle capacity andworking hours. Recently, cost and on-time delivery are the most important actors in logistics. Thus, the logistic applications attract attention of companies. In logistic management, determining the locations of delivery points and deciding the path are the vital components that should be considered. Deciding the paths of vehicles provides companies to use their vehicles efficiently. And with utilizing optimized paths, big amounts of cost and time savings will be gained. The main aim of the work is providing the best path according to the needs of the customers, minimizing the costs with utilizing the VRP and presenting an application for companies that need logistic management. To compare the results, simulated annealing is used on special scenarios. And t-test is performed in the study for the visited path in km with p-value of 0.05.
Murata, Tadahiko; Itai, Ryota
2008-01-01
In this chapter, we proposed a local search that can be used in a two-fold EMO algorithm for multiple-objective VRPs with different demands. The simulation results show that the proposed method have the fine effectiveness to enhance the similarity of obtained routes for vehicles. Although the local search slightly deteriorates the maximum duration, it improves the similarity of the routes that may decrease the possibility of getting lost the way of drivers. If drivers get lost their ways duri...
A Mathematical Model for the Industrial Hazardous Waste Location-Routing Problem
Boyer, Omid; Sai Hong, Tang; Pedram, Ali; Mohd Yusuff, Rosnah Bt; Zulkifli, Norzima
2013-01-01
Technology progress is a cause of industrial hazardous wastes increasing in the whole world . Management of hazardous waste is a significant issue due to the imposed risk on environment and human life. This risk can be a result of location of undesirable facilities and also routing hazardous waste. In this paper a biobjective mixed integer programing model for location-routing industrial hazardous waste with two objectives is developed. First objective is total cost minimization including tra...
Eroglu, Duygu Yilmaz; Gencosman, Burcu Caglar; Cavdur, Fatih; Ozmutlu, H Cenk
2014-01-01
In this paper, we analyze a real-world OVRP problem for a production company. Considering real-world constrains, we classify our problem as multicapacitated/heterogeneous fleet/open vehicle routing problem with split deliveries and multiproduct (MCHF/OVRP/SDMP) which is a novel classification of an OVRP. We have developed a mixed integer programming (MIP) model for the problem and generated test problems in different size (10-90 customers) considering real-world parameters. Although MIP is able to find optimal solutions of small size (10 customers) problems, when the number of customers increases, the problem gets harder to solve, and thus MIP could not find optimal solutions for problems that contain more than 10 customers. Moreover, MIP fails to find any feasible solution of large-scale problems (50-90 customers) within time limits (7200 seconds). Therefore, we have developed a genetic algorithm (GA) based solution approach for large-scale problems. The experimental results show that the GA based approach reaches successful solutions with 9.66% gap in 392.8 s on average instead of 7200 s for the problems that contain 10-50 customers. For large-scale problems (50-90 customers), GA reaches feasible solutions of problems within time limits. In conclusion, for the real-world applications, GA is preferable rather than MIP to reach feasible solutions in short time periods.
Insepov, Zeke; Veitzer, Seth; Mahalingam, Sudhakar
2011-01-01
Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, plasma initiation, plasma evolution, surface damage and gra- dient limits. We use simple PIC codes for modeling plasmas, molecular dynamics for modeling surface breakdown, and surface damage, and mesoscale surface thermodynamics and finite element electrostatic codes for to evaluate surface properties. Since any given experiment seems to have more variables than data points, we have tried to consider a wide variety of arcing (rf structures, e beam welding, laser ablation, etc.) to help constrain the problem, and concentrate on common mechanisms. While the mechanisms can be comparatively simple, modeling can be challenging.
DEFF Research Database (Denmark)
Wen, Min; Krapper, Emil; Larsen, Jesper;
This paper addresses an integrated vehicle routing and driver scheduling problem arising at the largest fresh meat producer in Denmark. The problem consists of a one-week planning horizon, heterogeneous vehicles, and drivers with predefi ned work regulations. These regulations include, among other...... things, predefined workdays, fixed starting time, maximum weekly working duration, break rule. The objective is to minimize the total delivery cost. The real-life case study is fi rst introduced and modelled as a mixed integer linear program. A multilevel variable neighborhood search heuristic...... of the aggregated problem is expanded to that of the original problem. The method is implemented and tested on real-life data consisting of up to 2000 orders per week. Computational results show that the aggregation procedure and the decomposition strategy are very effective in solving this large scale problem...
Meneghetti, M; Dahle, H; Limousin, M
2013-01-01
The existence of an arc statistics problem was at the center of a strong debate in the last fifteen years. With the aim to clarify if the optical depth for giant gravitational arcs by galaxy clusters in the so called concordance model is compatible with observations, several studies were carried out which helped to significantly improve our knowledge of strong lensing clusters, unveiling their extremely complex internal structure. In particular, the abundance and the frequency of strong lensing events like gravitational arcs turned out to be a potentially very powerful tool to trace the structure formation. However, given the limited size of observational and theoretical data-sets, the power of arc statistics as a cosmological tool has been only minimally exploited so far. On the other hand, the last years were characterized by significant advancements in the field, and several cluster surveys that are ongoing or planned for the near future seem to have the potential to make arc statistics a competitive cosmo...
Inverse problem of elastica of a variable-arc-length beam subjected to a concentrated load
Institute of Scientific and Technical Information of China (English)
Xiaowei Zhang; Jialing Yang; Keren Wang
2005-01-01
An inverse problem of elastica of a variable-arclength beam subjected to a concentrated load is investigated.The beam is fixed at one end, and can slide freely over a hinge support at the other end. The inverse problem is to determine the value of the load when the deflection of the action point of the load is given. Based on the elasitca equations and the elliptic integrals, a set of nonlinear equations for the inverse problem are derived, and an analytical solution by means of iterations and Quasi-Newton method is presented. From the results, the relationship between the loads and deflections of the loading point is obtained.
Refinements of the column generation process for the Vehicle Routing Problem with Time Windows
DEFF Research Database (Denmark)
Larsen, Jesper
2004-01-01
interval denoted the time window. The objective is to determine routes for the vehicles that minimizes the accumulated cost (or distance) with respect to the above mentioned constraints. Currently the best approaches for determining optimal solutions are based on column generation and Branch...
Tavakkoli-Moghaddam, Reza; Forouzanfar, Fateme; Ebrahimnejad, Sadoullah
2013-07-01
This paper considers a single-sourcing network design problem for a three-level supply chain. For the first time, a novel mathematical model is presented considering risk-pooling, the inventory existence at distribution centers (DCs) under demand uncertainty, the existence of several alternatives to transport the product between facilities, and routing of vehicles from distribution centers to customer in a stochastic supply chain system, simultaneously. This problem is formulated as a bi-objective stochastic mixed-integer nonlinear programming model. The aim of this model is to determine the number of located distribution centers, their locations, and capacity levels, and allocating customers to distribution centers and distribution centers to suppliers. It also determines the inventory control decisions on the amount of ordered products and the amount of safety stocks at each opened DC, selecting a type of vehicle for transportation. Moreover, it determines routing decisions, such as determination of vehicles' routes starting from an opened distribution center to serve its allocated customers and returning to that distribution center. All are done in a way that the total system cost and the total transportation time are minimized. The Lingo software is used to solve the presented model. The computational results are illustrated in this paper.
A Novel Discrete Differential Evolution Algorithm for the Vehicle Routing Problem in B2C E-Commerce
Xia, Chao; Sheng, Ying; Jiang, Zhong-Zhong; Tan, Chunqiao; Huang, Min; He, Yuanjian
2015-12-01
In this paper, a novel discrete differential evolution (DDE) algorithm is proposed to solve the vehicle routing problems (VRP) in B2C e-commerce, in which VRP is modeled by the incomplete graph based on the actual urban road system. First, a variant of classical VRP is described and a mathematical programming model for the variant is given. Second, the DDE is presented, where individuals are represented as the sequential encoding scheme, and a novel reparation operator is employed to repair the infeasible solutions. Furthermore, a FLOYD operator for dealing with the shortest route is embedded in the proposed DDE. Finally, an extensive computational study is carried out in comparison with the predatory search algorithm and genetic algorithm, and the results show that the proposed DDE is an effective algorithm for VRP in B2C e-commerce.
Flow Merging and Hub Route Optimization in Collaborative Transportation
Directory of Open Access Journals (Sweden)
Kerui Weng
2014-01-01
Full Text Available This paper studies the optimal hub routing problem of merged tasks in collaborative transportation. This problem allows all carriers’ transportation tasks to reach the destinations optionally passing through 0, 1, or 2 hubs within limited distance, while a cost discount on arcs in the hub route could be acquired after paying fixed charges. The problem arises in the application of logistics, postal services, airline transportation, and so forth. We formulate the problem as a mixed-integer programming model, and provide two heuristic approaches, respectively, based on Lagrangian relaxation and Benders decomposition. Computational experiments show that the algorithms work well.
Directory of Open Access Journals (Sweden)
Julia Rieck
2013-05-01
Full Text Available In reverse logistics networks, products (e.g., bottles or containers have to be transported from a depot to customer locations and, after use, from customer locations back to the depot. In order to operate economically beneficial, companies prefer a simultaneous delivery and pick-up service. The resulting Vehicle Routing Problem with Simultaneous Delivery and Pick-up (VRPSDP is an operational problem, which has to be solved daily by many companies. We present two mixed-integer linear model formulations for the VRPSDP, namely a vehicle-flow and a commodity-flow model. In order to strengthen the models, domain-reducing preprocessing techniques, and effective cutting planes are outlined. Symmetric benchmark instances known from the literature as well as new asymmetric instances derived from real-world problems are solved to optimality using CPLEX 12.1.
Solution Representations and Local Search for the bi-objective Inventory Routing Problem
Barthélemy, Thibaut; Sevaux, Marc
2012-01-01
The solution of the biobjective IRP is rather challenging, even for metaheuristics. We are still lacking a profound understanding of appropriate solution representations and effective neighborhood structures. Clearly, both the delivery volumes and the routing aspects of the alternatives need to be reflected in an encoding, and must be modified when searching by means of local search. Our work contributes to the better understanding of such solution representations. On the basis of an experimental investigation, the advantages and drawbacks of two encodings are studied and compared.
Institute of Scientific and Technical Information of China (English)
阴劼; 杨雯; 孔中华
2015-01-01
传统村落具有规模较小、景观点数量众多且分散、景观层次丰富和生产与生活性路网发达的特点。采取微观视角下的观景路线选线方法，在已有路网基础上提取最佳观景路线对于传统村落景观的保护与利用具有重要意义。研究以世界文化遗产之开平碉楼与村落为例，探索基于 ArcGIS 的空间视域选线方法：首先，通过要素提取分析和对象特征分析，建立要素数据库、界定景观的观赏效果，以景观数量多且质量好的点为最佳观景点；其次，综合利用 ArcGIS 表面、三维、缓冲分析工具在生产与生活性道路上分析各观景点的景观数量和质量，判断最佳观景点；最后，利用网络分析工具选取最佳观景路线。最佳观景点及最佳观景路线的选择有利于优化村落游赏规划、调整遗产保护范围，为遗产区管理和遗产保护提供新的思路。%Traditional vil ages have rich landscape and road network. Scenic route design is significant to traditional vil age landscape preservation and utilization. The paper studies viewing route design with ArcGIS technology in world cultural heritage site-Kaiping watchtowers case. Firstly analysis of landscape qualities recommend the best viewing points, then ArcGIS technology is used to analyze the amount and quality of dif erent viewpoints, and final y the best scenic route is defined by network tools. The best scenic route design wil help improve vil age planning and heritage preservation.
Ghoniem, Ahmed
2007-01-01
This dissertation addresses the development of enhanced formulations for minimax and mixed-integer programming models for certain industrial and logistical systems, along with the design and implementation of efficient algorithmic strategies. We first examine the general class of minimax mixed-integer 0-1 problems of the type that frequently arise in decomposition approaches and in a variety of location and scheduling problems. We conduct an extensive polyhedral analysis of this problem in o...
Does Calculation or Word-Problem Instruction Provide a Stronger Route to Prealgebraic Knowledge?
Fuchs, Lynn S.; Powell, Sarah R.; Cirino, Paul T.; Schumacher, Robin F.; Marrin, Sarah; Hamlett, Carol L.; Fuchs, Douglas; Compton, Donald L.; Changas, Paul C.
2014-01-01
The focus of this study was connections among 3 aspects of mathematical cognition at 2nd grade: calculations, word problems, and prealgebraic knowledge. We extended the literature, which is dominated by correlational work, by examining whether intervention conducted on calculations or word problems contributes to improved performance in the other…
Modelling Problem-Solving Situations into Number Theory Tasks: The Route towards Generalisation
Papadopoulos, Ioannis; Iatridou, Maria
2010-01-01
This paper examines the way two 10th graders cope with a non-standard generalisation problem that involves elementary concepts of number theory (more specifically linear Diophantine equations) in the geometrical context of a rectangle's area. Emphasis is given on how the students' past experience of problem solving (expressed through interplay…
Directory of Open Access Journals (Sweden)
Hao Yu
2016-05-01
Full Text Available Hazardous waste location-routing problems are of importance due to the potential risk for nearby residents and the environment. In this paper, an improved mathematical formulation is developed based upon a multi-objective mixed integer programming approach. The model aims at assisting decision makers in selecting locations for different facilities including treatment plants, recycling plants and disposal sites, providing appropriate technologies for hazardous waste treatment, and routing transportation. In the model, two critical factors are taken into account: system operating costs and risk imposed on local residents, and a compensation factor is introduced to the risk objective function in order to account for the fact that the risk level imposed by one type of hazardous waste or treatment technology may significantly vary from that of other types. Besides, the policy instruments for promoting waste recycling are considered, and their influence on the costs and risk of hazardous waste management is also discussed. The model is coded and calculated in Lingo optimization solver, and the augmented ε-constraint method is employed to generate the Pareto optimal curve of the multi-objective optimization problem. The trade-off between different objectives is illustrated in the numerical experiment.
Yu, Hao; Solvang, Wei Deng
2016-01-01
Hazardous waste location-routing problems are of importance due to the potential risk for nearby residents and the environment. In this paper, an improved mathematical formulation is developed based upon a multi-objective mixed integer programming approach. The model aims at assisting decision makers in selecting locations for different facilities including treatment plants, recycling plants and disposal sites, providing appropriate technologies for hazardous waste treatment, and routing transportation. In the model, two critical factors are taken into account: system operating costs and risk imposed on local residents, and a compensation factor is introduced to the risk objective function in order to account for the fact that the risk level imposed by one type of hazardous waste or treatment technology may significantly vary from that of other types. Besides, the policy instruments for promoting waste recycling are considered, and their influence on the costs and risk of hazardous waste management is also discussed. The model is coded and calculated in Lingo optimization solver, and the augmented ε-constraint method is employed to generate the Pareto optimal curve of the multi-objective optimization problem. The trade-off between different objectives is illustrated in the numerical experiment. PMID:27258293
Yu, Hao; Solvang, Wei Deng
2016-01-01
Hazardous waste location-routing problems are of importance due to the potential risk for nearby residents and the environment. In this paper, an improved mathematical formulation is developed based upon a multi-objective mixed integer programming approach. The model aims at assisting decision makers in selecting locations for different facilities including treatment plants, recycling plants and disposal sites, providing appropriate technologies for hazardous waste treatment, and routing transportation. In the model, two critical factors are taken into account: system operating costs and risk imposed on local residents, and a compensation factor is introduced to the risk objective function in order to account for the fact that the risk level imposed by one type of hazardous waste or treatment technology may significantly vary from that of other types. Besides, the policy instruments for promoting waste recycling are considered, and their influence on the costs and risk of hazardous waste management is also discussed. The model is coded and calculated in Lingo optimization solver, and the augmented ε-constraint method is employed to generate the Pareto optimal curve of the multi-objective optimization problem. The trade-off between different objectives is illustrated in the numerical experiment. PMID:27258293
Yu, Hao; Solvang, Wei Deng
2016-05-31
Hazardous waste location-routing problems are of importance due to the potential risk for nearby residents and the environment. In this paper, an improved mathematical formulation is developed based upon a multi-objective mixed integer programming approach. The model aims at assisting decision makers in selecting locations for different facilities including treatment plants, recycling plants and disposal sites, providing appropriate technologies for hazardous waste treatment, and routing transportation. In the model, two critical factors are taken into account: system operating costs and risk imposed on local residents, and a compensation factor is introduced to the risk objective function in order to account for the fact that the risk level imposed by one type of hazardous waste or treatment technology may significantly vary from that of other types. Besides, the policy instruments for promoting waste recycling are considered, and their influence on the costs and risk of hazardous waste management is also discussed. The model is coded and calculated in Lingo optimization solver, and the augmented ε-constraint method is employed to generate the Pareto optimal curve of the multi-objective optimization problem. The trade-off between different objectives is illustrated in the numerical experiment.
移动机会网络路由问题研究%Research on Mobile Network Opportunity Routing Problem
Institute of Scientific and Technical Information of China (English)
黎智成
2016-01-01
传统的多跳无线网络只适用于一般的用户，对于那些在比较困难的环境下进行作业的无线网络而言，一旦出现无线网络连接中断的情况，不仅会出现网络性能大幅度下降导致网络不能正常运行，更没有相应的处理方案来解决这种问题。这种网络显然不能满足当下人们的需求，因此移动机会网络应运而生。但这种网络的路由问题一直是人们关心的问题。在这里，文章主要就移动机会网络的实际应用以及机会路由问题进行简单的分析与研究。%Traditional jump more wireless network is only applicable to the general user, for those who are in a dififcult environment for operation of the wireless network, once appear, the wireless network connection interruption, can appear not only network performance led to a big drop in the network can not run normally, there is no corresponding treatment scheme to solve this problem. This network obviously can't meet the needs of the present people, so the mobile network opportunity accordingly. But this kind of network routing problem has always been a problem concerned by people. Here, we mainly is the practical application of mobile opportunities to network and the opportunity to study on simple analysis and routing problem.
Directory of Open Access Journals (Sweden)
Suphan Sodsoon
2014-06-01
Full Text Available This study aims to solve a Vehicle Routing Problem with Time Windows and Speed Limits (VRPTWSL, which has received considerable attention in recent years. The vehicle routing problem with time windows is an extension of the well-known Vehicle Routing Problem (VRP and involves a fleet of vehicles set of from a depot to serve a number of customers at different geographic locations with various demands within specific time and speed limits before returning to the depot eventually. To solve the problem, an efficient Saving Method-Max Min Ant System (Saving-MMAS with Local Search algorithm is applied. Using minimization of the total transportation costs as the objective of the extension VRPTWSL, a mathematic model is constructed. Finally, the Saving-MMAS algorithms indicated the good quality of the method in this problem.
Unified heuristics to solve routing problem of reverse logistics in sustainable supply chain
Anbuudayasankar, S. P.; Ganesh, K.; Lenny Koh, S. C.; Mohandas, K.
2010-03-01
A reverse logistics problem, motivated by many real-life applications, is examined where bottles/cans in which products are delivered from a processing depot to customers in one period are available for return to the depot in the following period. The picked-up bottles/cans need to be adjusted in the place of delivery load. This problem is termed as simultaneous delivery and pick-up problem with constrained capacity (SDPC). We develop three unified heuristics based on extended branch and bound heuristic, genetic algorithm and simulated annealing to solve SDPC. These heuristics are also designed to solve standard travelling salesman problem (TSP) and TSP with simultaneous delivery and pick-up (TSDP). We tested the heuristics on standard, derived and randomly generated datasets of TSP, TSDP and SDPC and obtained satisfying results with high convergence in reasonable time.
Lagrangian duality applied to the vehicle routing problem with time windows
DEFF Research Database (Denmark)
Kallehauge, Brian; Larsen, Jesper; Madsen, Oli B.G.
2006-01-01
) algorithm for the VRPTW. Making use of this acceleration strategy at the master problem level gives a significant speed-up compared to algorithms in the literature based on traditional column generation. We have solved two test problems introduced in 2001 by Gehring and Homberger with 400 and 1000 customers...... shortest path subproblem. We present a stabilized cutting-plane algorithm within the framework of linear programming for solving the associated Lagrangian dual problem. This algorithm creates easier constrained shortest path subproblems because less negative cycles are introduced and it leads to faster...... respectively, which to date are the largest problems ever solved to optimality. We have implemented the LBCP algorithm using the ABACUS open-source framework for solving mixed-integer linear-programs by branch, cut, and price....
Combining Single (Mixed) Metric Approach and Genetic Algorithm for QoS Routing Problem
Institute of Scientific and Technical Information of China (English)
胡世余; 谢剑英
2004-01-01
A hybrid algorithm for the delay constrained least cost path problem is proposed through combination of single (mixed) metric approach and genetic algorithm. Compared with the known genetic algorithm for the same problem, the new algorithm adopts integral coding scheme and new genetic operator, which reduces the search space and improves the efficiency of genetic operation. Meanwhile, the single (mixed) approach accelerates the convergence speed. Simulation results indicate that the proposed algorithm can find near-optimal even optimal solutions within moderate numbers of generations.
The Complex Route to Success: Complex Problem-Solving Skills in the Prediction of University Success
Stadler, Matthias J.; Becker, Nicolas; Greiff, Samuel; Spinath, Frank M.
2016-01-01
Successful completion of a university degree is a complex matter. Based on considerations regarding the demands of acquiring a university degree, the aim of this paper was to investigate the utility of complex problem-solving (CPS) skills in the prediction of objective and subjective university success (SUS). The key finding of this study was that…
Directory of Open Access Journals (Sweden)
Reshani P. Liyanage
2016-08-01
Full Text Available This paper is focused on the growing need of integrating environmentally sound choices into supply-chain management. The concept of green economic practices driven by the environmental sustainability challenges posed the concept of green logistics, to evolve in the last few decades.To establish the field further, the purpose of this paper is twofold. First, it offers anextensive systematic review of literature on GL with a critical review of the studies that have been considered in the paper.Second, it offers a conceptual analytical model where the canonical capacitated vehicle routing problem is extended to add the measures of Carbon Dioxide (CO2 emissions. The proposed, multi objective optimization model tackles the conflicting objectives of CO2 emission reduction and cost minimization. The developed generic model integrates the traffic information in providing the user with opportunity to have more realistic solution. The model also enables strategic decision making to improve the GL operations while allowing greatercompetitive advantage
Directory of Open Access Journals (Sweden)
Michael Polacek
2008-12-01
Full Text Available In this paper we propose two cooperation schemes to compose new parallel variants of the Variable Neighborhood Search (VNS. On the one hand, a coarse-grained cooperation scheme is introduced which is well suited for being enhanced with a solution warehouse to store and manage the so far best found solutions and a self-adapting mechanism for the most important search parameters. This makes an a priori parameter tuning obsolete. On the other hand, a fine-grained scheme was designed to reproduce the successful properties of the sequential VNS. In combination with the use of parallel exploration threads all of the best solutions and 11 out of 20 new best solutions for the Multi Depot Vehicle Routing Problem with Time Windows were found.
Directory of Open Access Journals (Sweden)
Majid Yousefikhoshbakht
2016-07-01
Full Text Available The TSP is considered one of the most well-known combinatorial optimization tasks and researchers have paid so much attention to the TSP for many years. In this problem, a salesman starts to move from an arbitrary place called depot and after visits all of the nodes, finally comes back to the depot. The objective is to minimize the total distance traveled by the salesman. Because this problem is a non-deterministic polynomial (NP-hard problem in nature, a hybrid meta-heuristic algorithm called REACSGA is used for solving the TSP. In REACSGA, a reactive bone route algorithm that uses the ant colony system (ACS for generating initial diversified solutions and the genetic algorithm (GA as an improved procedure are applied. Since the performance of the Metaheuristic algorithms is significantly influenced by their parameters, Taguchi Method is used to set the parameters of the proposed algorithm. The proposed algorithm is tested on several standard instances involving 24 to 318 nodes from the literature. The computational result shows that the results of the proposed algorithm are competitive with other metaheuristic algorithms for solving the TSP in terms of better quality of solution and computational time respectively. In addition, the proposed REACSGA is significantly efficient and finds closely the best known solutions for most of the instances in which thirteen best known solutions are also found.
Directory of Open Access Journals (Sweden)
Lin Zhou
2016-08-01
Full Text Available With the increasing interest in online shopping, the Last Mile delivery is regarded as one of the most expensive and pollutive—and yet the least efficient—stages of the e-commerce supply chain. To address this challenge, a novel location-routing problem with simultaneous home delivery and customer’s pickup is proposed. This problem aims to build a more effective Last Mile distribution system by providing two kinds of service options when delivering packages to customers. To solve this specific problem, a hybrid evolution search algorithm by combining genetic algorithm (GA and local search (LS is presented. In this approach, a diverse population generation algorithm along with a two-phase solution initialization heuristic is first proposed to give high quality initial population. Then, advantaged solution representation, individual evaluation, crossover and mutation operations are designed to enhance the evolution and search efficiency. Computational experiments based on a large family of instances are conducted, and the results obtained indicate the validity of the proposed model and method.
Bodirsky, Manuel
2008-01-01
This paper studies peek arc consistency, a reasoning technique that extends the well-known arc consistency technique for constraint satisfaction. In contrast to other more costly extensions of arc consistency that have been studied in the literature, peek arc consistency requires only linear space and quadratic time and can be parallelized in a straightforward way such that it runs in linear time with a linear number of processors. We demonstrate that for various constraint languages, peek arc consistency gives a polynomial-time decision procedure for the constraint satisfaction problem. We also present an algebraic characterization of those constraint languages that can be solved by peek arc consistency, and study the robustness of the algorithm.
The home health care routing and scheduling problem with interdependent services.
Mankowska, Dorota Slawa; Meisel, Frank; Bierwirth, Christian
2014-03-01
This paper presents a model for the daily planning of health care services carried out at patients' homes by staff members of a home care company. The planning takes into account individual service requirements of the patients, individual qualifications of the staff and possible interdependencies between different service operations. Interdependencies of services can include, for example, a temporal separation of two services as is required if drugs have to be administered a certain time before providing a meal. Other services like handling a disabled patient may require two staff members working together at a patient's home. The time preferences of patients are included in terms of given time windows. In this paper, we propose a planning approach for the described problem, which can be used for optimizing economical and service oriented measures of performance. A mathematical model formulation is proposed together with a powerful heuristic based on a sophisticated solution representation. PMID:23780750
Visualizing Internet routing changes.
Lad, Mohit; Massey, Dan; Zhang, Lixia
2006-01-01
Today's Internet provides a global data delivery service to millions of end users and routing protocols play a critical role in this service. It is important to be able to identify and diagnose any problems occurring in Internet routing. However, the Internet's sheer size makes this task difficult. One cannot easily extract out the most important or relevant routing information from the large amounts of data collected from multiple routers. To tackle this problem, we have developed Link-Rank, a tool to visualize Internet routing changes at the global scale. Link-Rank weighs links in a topological graph by the number of routes carried over each link and visually captures changes in link weights in the form of a topological graph with adjustable size. Using Link-Rank, network operators can easily observe important routing changes from massive amounts of routing data, discover otherwise unnoticed routing problems, understand the impact of topological events, and infer root causes of observed routing changes.
Cain, Bruce L.
1990-01-01
The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.
BGP路由收敛问题及其解决方案研究%Research of BGP Routing Convergence Problem and Solution
Institute of Scientific and Technical Information of China (English)
王洪君; 苑卫鑫; 刘毅; 尚大龙
2015-01-01
The Border Gateway Protocol( BGP)is the only inter-domain routing protocol running on the Internet. BGP routing divergence and slow convergence problem were studied in the paper. The reason for the BGP routing divergent and slow convergence was also discussed. The existing solutions to these problems were summarized. The advantages and disadvantages of these solutions were comparatively analyzed.%BGP协议是运行于Internet上的唯一的域间路由协议。本文对BGP路由发散问题和慢收敛问题进行了研究，论述了BGP路由发散问题和慢收敛问题产生的原因，并对现有解决方案进行了综述，分析比较了这些方案的优缺点。
Directory of Open Access Journals (Sweden)
Yanhui Li
2013-01-01
Full Text Available Facility location, inventory control, and vehicle routes scheduling are critical and highly related problems in the design of logistics system for e-business. Meanwhile, the return ratio in Internet sales was significantly higher than in the traditional business. Many of returned merchandise have no quality defects, which can reenter sales channels just after a simple repackaging process. Focusing on the existing problem in e-commerce logistics system, we formulate a location-inventory-routing problem model with no quality defects returns. To solve this NP-hard problem, an effective hybrid genetic simulated annealing algorithm (HGSAA is proposed. Results of numerical examples show that HGSAA outperforms GA on computing time, optimal solution, and computing stability. The proposed model is very useful to help managers make the right decisions under e-supply chain environment.
Li, Yanhui; Guo, Hao; Wang, Lin; Fu, Jing
2013-01-01
Facility location, inventory control, and vehicle routes scheduling are critical and highly related problems in the design of logistics system for e-business. Meanwhile, the return ratio in Internet sales was significantly higher than in the traditional business. Many of returned merchandise have no quality defects, which can reenter sales channels just after a simple repackaging process. Focusing on the existing problem in e-commerce logistics system, we formulate a location-inventory-routing problem model with no quality defects returns. To solve this NP-hard problem, an effective hybrid genetic simulated annealing algorithm (HGSAA) is proposed. Results of numerical examples show that HGSAA outperforms GA on computing time, optimal solution, and computing stability. The proposed model is very useful to help managers make the right decisions under e-supply chain environment.
Li, Yanhui; Guo, Hao; Wang, Lin; Fu, Jing
2013-01-01
Facility location, inventory control, and vehicle routes scheduling are critical and highly related problems in the design of logistics system for e-business. Meanwhile, the return ratio in Internet sales was significantly higher than in the traditional business. Many of returned merchandise have no quality defects, which can reenter sales channels just after a simple repackaging process. Focusing on the existing problem in e-commerce logistics system, we formulate a location-inventory-routing problem model with no quality defects returns. To solve this NP-hard problem, an effective hybrid genetic simulated annealing algorithm (HGSAA) is proposed. Results of numerical examples show that HGSAA outperforms GA on computing time, optimal solution, and computing stability. The proposed model is very useful to help managers make the right decisions under e-supply chain environment. PMID:24489489
Yanhui Li; Hao Guo; Lin Wang; Jing Fu
2013-01-01
Facility location, inventory control, and vehicle routes scheduling are critical and highly related problems in the design of logistics system for e-business. Meanwhile, the return ratio in Internet sales was significantly higher than in the traditional business. Many of returned merchandise have no quality defects, which can reenter sales channels just after a simple repackaging process. Focusing on the existing problem in e-commerce logistics system, we formulate a location-inventory-routin...
Shuai Deng; Yanhui Li; Hao Guo; Bailing Liu
2016-01-01
This paper presents a closed-loop location-inventory-routing problem model considering both quality defect returns and nondefect returns in e-commerce supply chain system. The objective is to minimize the total cost produced in both forward and reverse logistics networks. We propose a combined optimization algorithm named hybrid ant colony optimization algorithm (HACO) to address this model that is an NP-hard problem. Our experimental results show that the proposed HACO is considerably effici...
Road and Street Centerlines - MO 2011 October MoDOT Roads - Routes (GDB)
NSGIC GIS Inventory (aka Ramona) — Routes represent a single linear feature, such as a city street or highway. Routes are linear features composed of one or more arcs or parts of an arc; for example,...
Road and Street Centerlines - MO 2010 June MoDOT Roads - Routes (GDB)
NSGIC GIS Inventory (aka Ramona) — Routes represent a single linear feature, such as a city street or highway. Routes are linear features composed of one or more arcs or parts of an arc; for example,...
Sun, Yan; Lang, Maoxiang; Wang, Danzhu
2016-07-28
The transportation of hazardous materials is always accompanied by considerable risk that will impact public and environment security. As an efficient and reliable transportation organization, a multimodal service should participate in the transportation of hazardous materials. In this study, we focus on transporting hazardous materials through the multimodal service network and explore the hazardous materials multimodal routing problem from the operational level of network planning. To formulate this problem more practicably, minimizing the total generalized costs of transporting the hazardous materials and the social risk along the planned routes are set as the optimization objectives. Meanwhile, the following formulation characteristics will be comprehensively modelled: (1) specific customer demands; (2) multiple hazardous material flows; (3) capacitated schedule-based rail service and uncapacitated time-flexible road service; and (4) environmental risk constraint. A bi-objective mixed integer nonlinear programming model is first built to formulate the routing problem that combines the formulation characteristics above. Then linear reformations are developed to linearize and improve the initial model so that it can be effectively solved by exact solution algorithms on standard mathematical programming software. By utilizing the normalized weighted sum method, we can generate the Pareto solutions to the bi-objective optimization problem for a specific case. Finally, a large-scale empirical case study from the Beijing-Tianjin-Hebei Region in China is presented to demonstrate the feasibility of the proposed methods in dealing with the practical problem. Various scenarios are also discussed in the case study.
Sun, Yan; Lang, Maoxiang; Wang, Danzhu
2016-01-01
The transportation of hazardous materials is always accompanied by considerable risk that will impact public and environment security. As an efficient and reliable transportation organization, a multimodal service should participate in the transportation of hazardous materials. In this study, we focus on transporting hazardous materials through the multimodal service network and explore the hazardous materials multimodal routing problem from the operational level of network planning. To formulate this problem more practicably, minimizing the total generalized costs of transporting the hazardous materials and the social risk along the planned routes are set as the optimization objectives. Meanwhile, the following formulation characteristics will be comprehensively modelled: (1) specific customer demands; (2) multiple hazardous material flows; (3) capacitated schedule-based rail service and uncapacitated time-flexible road service; and (4) environmental risk constraint. A bi-objective mixed integer nonlinear programming model is first built to formulate the routing problem that combines the formulation characteristics above. Then linear reformations are developed to linearize and improve the initial model so that it can be effectively solved by exact solution algorithms on standard mathematical programming software. By utilizing the normalized weighted sum method, we can generate the Pareto solutions to the bi-objective optimization problem for a specific case. Finally, a large-scale empirical case study from the Beijing–Tianjin–Hebei Region in China is presented to demonstrate the feasibility of the proposed methods in dealing with the practical problem. Various scenarios are also discussed in the case study. PMID:27483294
Sun, Yan; Lang, Maoxiang; Wang, Danzhu
2016-01-01
The transportation of hazardous materials is always accompanied by considerable risk that will impact public and environment security. As an efficient and reliable transportation organization, a multimodal service should participate in the transportation of hazardous materials. In this study, we focus on transporting hazardous materials through the multimodal service network and explore the hazardous materials multimodal routing problem from the operational level of network planning. To formulate this problem more practicably, minimizing the total generalized costs of transporting the hazardous materials and the social risk along the planned routes are set as the optimization objectives. Meanwhile, the following formulation characteristics will be comprehensively modelled: (1) specific customer demands; (2) multiple hazardous material flows; (3) capacitated schedule-based rail service and uncapacitated time-flexible road service; and (4) environmental risk constraint. A bi-objective mixed integer nonlinear programming model is first built to formulate the routing problem that combines the formulation characteristics above. Then linear reformations are developed to linearize and improve the initial model so that it can be effectively solved by exact solution algorithms on standard mathematical programming software. By utilizing the normalized weighted sum method, we can generate the Pareto solutions to the bi-objective optimization problem for a specific case. Finally, a large-scale empirical case study from the Beijing-Tianjin-Hebei Region in China is presented to demonstrate the feasibility of the proposed methods in dealing with the practical problem. Various scenarios are also discussed in the case study. PMID:27483294
Tabu Search Technique for Solving the Routing Problem%禁忌搜索算法用于解决网络路由问题
Institute of Scientific and Technical Information of China (English)
王东平; 李绍荣
2003-01-01
Routing problem is a very import problem in the network design. However, with the increasing of the number of vertices, the convergence speed of the conventional method (such as the Dijkstra algorithm) becomes slow. In some services, the accurate shortest path isn't requested. This paper presents a new algorithm for solving this problem based on the tabu search technique. The tabu search algorithm can get the satisfied path with the changing of the iteration times, the tabu period and neighborhood size. Simulation results demonstrate that the proposed method is very efficient for computing the shorted path, especially when the scale of the network is large.
Ghezavati, V. R.; Beigi, M.
2016-06-01
During the last decade, the stringent pressures from environmental and social requirements have spurred an interest in designing a reverse logistics (RL) network. The success of a logistics system may depend on the decisions of the facilities locations and vehicle routings. The location-routing problem (LRP) simultaneously locates the facilities and designs the travel routes for vehicles among established facilities and existing demand points. In this paper, the location-routing problem with time window (LRPTW) and homogeneous fleet type and designing a multi-echelon, and capacitated reverse logistics network, are considered which may arise in many real-life situations in logistics management. Our proposed RL network consists of hybrid collection/inspection centers, recovery centers and disposal centers. Here, we present a new bi-objective mathematical programming (BOMP) for LRPTW in reverse logistic. Since this type of problem is NP-hard, the non-dominated sorting genetic algorithm II (NSGA-II) is proposed to obtain the Pareto frontier for the given problem. Several numerical examples are presented to illustrate the effectiveness of the proposed model and algorithm. Also, the present work is an effort to effectively implement the ɛ-constraint method in GAMS software for producing the Pareto-optimal solutions in a BOMP. The results of the proposed algorithm have been compared with the ɛ-constraint method. The computational results show that the ɛ-constraint method is able to solve small-size instances to optimality within reasonable computing times, and for medium-to-large-sized problems, the proposed NSGA-II works better than the ɛ-constraint.
The hardness of routing two pairs on one face
Naves, Guyslain
2009-01-01
We prove the NP-completeness of the integer multiflow problem in planar graphs, with the following restrictions: there are only two demand edges, both lying on the infinite face of the routing graph. This was one of the open challenges concerning disjoint paths, explicitly asked by M\\"uller. It also strengthens Schw\\"arzler's recent proof of one of the open problems of Schrijver's book, about the complexity of the edge-disjoint paths problem with terminals on the outer boundary of a planar graph. We also give a directed acyclic reduction. This proves that the arc-disjoint paths problem is NP-complete in directed acyclic graphs, even with only two demand arcs.
Directory of Open Access Journals (Sweden)
Bailing Liu
2015-01-01
Full Text Available Facility location, inventory control, and vehicle routes scheduling are three key issues to be settled in the design of logistics system for e-commerce. Due to the online shopping features of e-commerce, customer returns are becoming much more than traditional commerce. This paper studies a three-phase supply chain distribution system consisting of one supplier, a set of retailers, and a single type of product with continuous review (Q, r inventory policy. We formulate a stochastic location-inventory-routing problem (LIRP model with no quality defects returns. To solve the NP-hand problem, a pseudo-parallel genetic algorithm integrating simulated annealing (PPGASA is proposed. The computational results show that PPGASA outperforms GA on optimal solution, computing time, and computing stability.
Arc-preserving subsequences of arc-annotated sequences
Popov, Vladimir Yu
2011-01-01
Arc-annotated sequences are useful in representing the structural information of RNA and protein sequences. The longest arc-preserving common subsequence problem has been introduced as a framework for studying the similarity of arc-annotated sequences. In this paper, we consider arc-annotated sequences with various arc structures. We consider the longest arc preserving common subsequence problem. In particular, we show that the decision version of the 1-{\\sc fragment LAPCS(crossing,chain)} and the decision version of the 0-{\\sc diagonal LAPCS(crossing,chain)} are {\\bf NP}-complete for some fixed alphabet $\\Sigma$ such that $|\\Sigma| = 2$. Also we show that if $|\\Sigma| = 1$, then the decision version of the 1-{\\sc fragment LAPCS(unlimited, plain)} and the decision version of the 0-{\\sc diagonal LAPCS(unlimited, plain)} are {\\bf NP}-complete.
Solutions for Route Selection Problem Based on Activity-based Costing%基于作业成本法的路径选择问题
Institute of Scientific and Technical Information of China (English)
王婷; 赵启兰
2011-01-01
Through analyzing systematically the compesition of the logistics cost involved in route selection problems, the paper proposes the route selection model based on activity-based costing and, through analyzing the practical needs of route selection, identifying the driving factors of the process, establishing cost base and the apportionment procedure, calculates the indirect cost in transportation activities, which renders the calculation of cost, the most important factor to consider in route selection, more accurate. Finally a case study involving the coal transportation group MD is carried out to verify the effectiveness of the model.%通过在路径选择问题中物流成本构成的系统分析,提出了基于作业成本法的路径选择模型.分析路径选择的实际需要,经过确定资源动因,建立成本库、分摊等过程,计算了运输所涉及的间接成本,使路径选择最重要的考虑因素一成本的计算更为精确,从而减少决策时的误差.并以MD集团煤炭运输为例,进行了计算.为管理者进行以成本为目标的路径选择提供了更准确的依据.
Directory of Open Access Journals (Sweden)
Shuai Deng
2016-01-01
Full Text Available This paper presents a closed-loop location-inventory-routing problem model considering both quality defect returns and nondefect returns in e-commerce supply chain system. The objective is to minimize the total cost produced in both forward and reverse logistics networks. We propose a combined optimization algorithm named hybrid ant colony optimization algorithm (HACO to address this model that is an NP-hard problem. Our experimental results show that the proposed HACO is considerably efficient and effective in solving this model.
Study on vehicle routing problem based on heuristic ant colony optimization%基于启发式蚁群算法的VRP问题研究
Institute of Scientific and Technical Information of China (English)
刘晓勇; 付辉
2011-01-01
When Ant Colony Optimization algorithm (ACO) is applied to vehicle routing problem, it always spends much time and has worse solutions.This paper uses ACO based on a heuristic method for vehicle routing problem.This heuristic method combines distance matrix with saving route matrix to assign initial pheromone matrix.Three benchmark datasets are chosen to verify performance of the new algorithm. Experiments show that ant colony optimization based on heuristic information has better solution and spends less time.%针对蚁群算法求解VRP问题时收敛速度慢,求解质量不高的缺点,把城市和仓库间的距离矩阵和路径节约矩阵信息融入到初始信息素矩阵中作为启发式信息引入到蚁群算法中用于求解有容量限制的车辆路径规划问题(CVRP),在三个基准数据集上的实验研究表明,基于启发式信息的蚁群算法与基本蚁群算法相比能够以较快的速度收敛到较好的解.
A novel methodology for determining low-cost fine particulate matter street sweeping routes.
Blazquez, Carola A; Beghelli, Alejandra; Meneses, Veronica P
2012-02-01
This paper addresses the problem of low-cost PM10 (particulate matter with aerodynamic diameter route. In order to do so, only a subset of the streets of the urban area to be swept is selected for sweeping, based on their PM10 emission factor values. Subsequently, a low-cost route that visits each street in the set is computed. Unlike related problems of waste collection where streets must be visited once (Chinese or Rural Postman Problem, respectively), in this case, the sweeping vehicle route must visit each selected street exactly as many times as its number of street sides, since the vehicle can sweep only one street side at a time. Additionally, the route must comply with traffic flow and turn constraints. A novel transformation of the original arc routing problem into a node routing problem is proposed in this paper. This is accomplished by building a graph that represents the area to sweep in such a way that the problem can be solved by applying any known solution to the Traveling Salesman Problem (TSP). As a way of illustration, the proposed method was applied to the northeast area of the Municipality of Santiago (Chile). Results show that the proposed methodology achieved up to 37% savings in kilometers traveled by the sweeping vehicle when compared to the solution obtained by solving the TSP problem with Geographic Information Systems (GIS)--aware tools.
Modeling Routing Overhead Generated by Wireless Proactive Routing Protocols
Javaid, Nadeem; Javaid, Akmal; Malik, Shahzad A
2011-01-01
In this paper, we present a detailed framework consisting of modeling of routing overhead generated by three widely used proactive routing protocols; Destination-Sequenced Distance Vector (DSDV), Fish-eye State Routing (FSR) and Optimized Link State Routing (OLSR). The questions like, how these protocols differ from each other on the basis of implementing different routing strategies, how neighbor estimation errors affect broadcast of route requests, how reduction of broadcast overhead achieves bandwidth, how to cope with the problem of mobility and density, etc, are attempted to respond. In all of the above mentioned situations, routing overhead and delay generated by the chosen protocols can exactly be calculated from our modeled equations. Finally, we analyze the performance of selected routing protocols using our proposed framework in NS-2 by considering different performance parameters; Route REQuest (RREQ) packet generation, End-to-End Delay (E2ED) and Normalized Routing Load (NRL) with respect to varyi...
基于ACS-GA算法的车辆路径问题研究%An ACS-GA Hybrid Optimization Method to Solve Vehicle Routing Problem
Institute of Scientific and Technical Information of China (English)
赵婉忻; 曲仕茹
2011-01-01
Vehicle routing problem is an important research area in intelligent transportation and business logistics. Planning the vehicle routes reasonably, reducing the delivery mileage and minimizing the cost of logistic distribution are great significance to increase economic efficiency. The paper focuses on vehicle routing problem with time windows in logistic distribution and establishes an improved mathematical model in which the delivery time and delivery distance is shortest. A novel hybrid optimization method integrating ant colony system with genetic algorithm ( ACS - GA) is presented. The initial solution is obtained by ant colony system. A genetic algorithm is used to improve the performance of ACS by reproduction, crossover and mutation operations. The ACS - GA hybrid optimization method can overcome the premature phenomenon and enhance the global search ability. Based on the benchmark datasets of vehicle routing problem with time windows, the experimental results demonstrate that the proposed method has a better ability to search the global optimal solution than other optimization methods.%物流配送车辆路径问题是智能交通和商业物流领域中一个重要研究方面.合理规划车辆的行驶路线,减少配送里程,降低物流成本,对提高经济效益具有重要意义.重点分析了带时间窗的物流配送车辆路径问题,建立了兼顾配送时间与配送距离最短的改进数学模型.提出了基于蚁群系统算法和遗传算法相融合的混合算法.该算法利用蚁群系统算法得到初始解,运用遗传算法中复制、交叉、变异操作对解的种群多样性进行扩充,克服了蚁群系统算法的早熟现象,增强了算法的全局搜索能力.基于标准数据集的实验结果表明,该算法与其他优化方法相比较,具有较好的搜索车辆路径最优解的能力.
FASTER MUSE CSP ARC CONSISTENCY ALGORITHMS
Harper, Mary P.; White, Christopher M.; Helzerman, Randall A.; Hockema, Stephen A.
1997-01-01
MUSE CSP (Multiply SEgmented Constraint Satisfaction Problem) [5, 61 is an extension to the constraint satisfaction problem (CSP) which is especially useful for problems that segment into riultiple instances of CSP that share variables. In Belzerman and Harper [6], the concepts of MUSE node, arc, and path consistency were defined and algorithms for MUSE arc consistency, MUSE AC-1, and MUSE path consistency were developed. MUSE AC-1 is similar to the CSP arc consistency algorithm AC-4 [ l j ] ...
Directory of Open Access Journals (Sweden)
Yu Lin
2015-01-01
Full Text Available In recent years, logistics systems with multiple suppliers and plants in neighboring regions have been flourishing worldwide. However, high logistics costs remain a problem for such systems due to lack of information sharing and cooperation. This paper proposes an extended mathematical model that minimizes transportation and pipeline inventory costs via the many-to-many Milk-run routing mode. Because the problem is NP hard, a two-stage heuristic algorithm is developed by comprehensively considering its characteristics. More specifically, an initial satisfactory solution is generated in the first stage through a greedy heuristic algorithm to minimize the total number of vehicle service nodes and the best insertion heuristic algorithm to determine each vehicle’s route. Then, a simulated annealing algorithm (SA with limited search scope is used to improve the initial satisfactory solution. Thirty numerical examples are employed to test the proposed algorithms. The experiment results demonstrate the effectiveness of this algorithm. Further, the superiority of the many-to-many transportation mode over other modes is demonstrated via two case studies.
Clustering algorithm for split delivery vehicle routing problem%需求可拆分车辆路径问题的聚类求解算法
Institute of Scientific and Technical Information of China (English)
刘旺盛; 杨帆; 李茂青; 陈培芝
2012-01-01
In the traditional vehicle routing problems, customer demands are usually assumed that they can not be split. That is to say, a customer can only be severed by a vehicle. In fact, split delivery requires fewer vehicles, which reduces transportation costs. This paper analyzes the solution＇s characteristics of split delivery vehicle routing problem, and also proves the situations that customers＇ demands can not be split. A clustering algorithm meeting the solution＇s characteristics is designed to solve this problem. Compared with ant colony algorithm and tabu search algorithm, the proposed algorithm is demonstrated to obtain optimal solution more effectively through the simulation, and it is an effective method to solve split delivery vehicle routing problem.%针对传统的车辆路径问题通常假设客户的需求不能拆分，即客户的需求由一辆车满足，而实际上通过需求的拆分可使需要的车辆数更少，从而降低配送成本的问题，分析了需求可拆分的车辆路径问题的解的特征，证明了客户需求不宜拆分应满足的条件，设计了符合解的特征的聚类算法，并对其求解．通过实验仿真，将所提出的聚类算法与蚁群算法和禁忌搜索算法进行比较，所得结果表明了所提出的算法可以更有效地求得需求可拆分车辆路径问题的优化解，是解决需求町拆分车辆路径问题的有效方法．
PNW River Reach Files -- 1:100k LLID Routed Streams (routes)
Pacific States Marine Fisheries Commission — This feature class includes the ROUTE features from the 2001 version of the PNW River Reach files Arc/INFO coverage. Separate, companion feature classes are also...
A novel methodology for determining low-cost fine particulate matter street sweeping routes.
Blazquez, Carola A; Beghelli, Alejandra; Meneses, Veronica P
2012-02-01
This paper addresses the problem of low-cost PM10 (particulate matter with aerodynamic diameter arc routing problem into a node routing problem is proposed in this paper. This is accomplished by building a graph that represents the area to sweep in such a way that the problem can be solved by applying any known solution to the Traveling Salesman Problem (TSP). As a way of illustration, the proposed method was applied to the northeast area of the Municipality of Santiago (Chile). Results show that the proposed methodology achieved up to 37% savings in kilometers traveled by the sweeping vehicle when compared to the solution obtained by solving the TSP problem with Geographic Information Systems (GIS)--aware tools. PMID:22442940
物流配送车辆调度问题算法综述%Research on Algorithm of Delivery Vehicle Routing Problems
Institute of Scientific and Technical Information of China (English)
陈君兰; 叶春明
2012-01-01
Delivery vehicle routing problems （VRP） is a kind of optimization problems, aiming at solving the vehicle routing problems in delivery section. And they have been a focus of research in logistics control optimization recently. After summarize different kinds of VRP, the article gives the relevant general models. The character and the application of genetic algorithm, simulated annealing, tabu search, ant colony algorithm, particle swarm optimization are analyzed and the current possibilities to solve VRP are also discussed. Finally, the development of VRP solution is presented, and point out that improved combined algorithm as well as new algorithm will be important measures to solve VRP.%配送车辆调度优化问题旨在解决配送中路径和车辆调度问题的一类组合优化问题，是近年来物流控制优化领域的研究热点。文章对运输调度问题进行了分类总结，给出总体模型的概括描述，分析遗传算法、模拟退火算法、禁忌搜索算法、蚁群算法和微粒群算法的特点及其在求解配送车辆调度优化问题中的求解思路，并讨论了其求解现状，对未来研究方向进行展望，指出改进混合现有算法，开拓新算法将是更有效解决配送车辆调度问题的好方法。
需求可拆分的开放式车辆路径问题研究%Research on Split Delivery Open Vehicle Routing Problem
Institute of Scientific and Technical Information of China (English)
李三彬; 柴玉梅; 王黎明
2011-01-01
The traditional Open Vehicle Routing Problem(OVRP) assumes that the demand of the clients can not be split and the type of vehicles is the same, but in the practical logistics distribution, the type of vehicles is not exactly the same, sometimes the transportation cost can be reduced by splitting the demand of clients to make the best of the loading capacity of vehicles.This paper proposes the Split Delivery Open Vehicle Routing Problem with Heterogeneous Vehicles(SDOVRPHV), presents mathematic model of the integer programming of the problem, solves it with Tabu search algorithm and improves the generation of the initial solution and neighborhood structure in the algorithm.By experiments, the validity of the model is validated, and the results are compared with the traditional OVRP which indicates that the algorithm can reduce effectively the transportation cost.%传统的开放式车辆路径问题假设客户的需求不可拆分、车辆类型相同,但在实际的物流配送中,车辆类型不完全相同,对需求的拆分能充分利用车辆的装载能力,降低运输成本.为此,提出需求可拆分的不同种车辆的开放式车辆路径问题,给出整数规划的数学模型,利用禁忌搜索算法对该问题求解,改进算法中初始解和邻域结构的产生过程.通过实验验证模型的有效性,并将结果与传统的开放式车辆路径问题进行比较,表明该算法可有效减少运输成本.
A branch-and-cut-and-price approach for the pickup and delivery problem with shuttle routes
DEFF Research Database (Denmark)
Masson, Renaud; Røpke, Stefan; Lehuédé, Fabien;
2014-01-01
for the PDPS and a branch-and-cut-and-price algorithm to solve it. The pricing sub-problem, an Elementary Shortest Path Problem with Resource Constraints (ESPPRC), is solved with a labeling algorithm enhanced with efficient dominance rules. Three families of valid inequalities are used to strengthen...... the quality of linear relaxations. The method is evaluated on generated and real-world instances containing up to 193 transportation requests. Instances with up to 87 customers are solved to optimality within a computation time of one hour....
Graph theoretic approach for routing problem in VLSI%基于图论模型的一类集成电路布线算法
Institute of Scientific and Technical Information of China (English)
耿显亚; 许峰
2015-01-01
针对具有曼哈顿模型的一类通道布线，提出了一个依据图论模型的最优轨道高度布线算法。算法根据通道上结点的水平约束图和垂直约束图，依次安排好每一个结点的布线轨道，进而通过通孔可以把所有的结点在2层轨道上布线完成。通过计算分析，该算法相对以前的算法能够达到更优的布线高度，并且其复杂性保持不变。%For a channel in 2-layer Manhattan model, this paper aims at interconnecting the terminals of each net by wires such that the circuit elements and the interconnecting wires are embedded into two planar layers by the methods of graph theory. Furthermore, the width(number of tracks required for routing)of a channel should be minimized. The constraints of a channel routing problem can be represented by a Horizontal Constraint Graph(HCG)and a Vertical Constraint Graph (VCG). Considering the two constraints, the paper improves the upper bound, it shows that this algorithm is better than the best known algorithm.
基于模糊期望值模型的车辆路径问题%Vehicle routing problem based on fuzzy expected value model
Institute of Scientific and Technical Information of China (English)
王连锋; 宋建社; 杨正磊; 曹继平
2012-01-01
Aiming at the vehicle routing problem with fuzzy demands, the probability of vehicle service failure was analyzed based on fuzzy credibility theory, and a fuzzy expected value model was formulated. A parallel particle swarm optimization with double layers tabu search was proposed for routes optimization. In this algorithm, two different types of tabu search space were inserted, and two neighborhood arithmetic operators were designed by using new iterative formula and roulette strategy. The effectiveness of proposed method was verified by simulation contrast tests.%针对模糊需求的车辆路径问题，基于模糊可信性理论对车辆服务失败事件进行可能性分析，建立了一个模糊期望值模型，提出一种带双层禁忌搜索的并行粒子群算法。该算法引入两种不同的禁忌空间，采用新的粒子迭代公式，并利用轮盘赌策略设计了两类邻域算子。通过仿真对比实验表明了该算法的有效性。
Using Genetic Algorithm For Winter Maintenance Operations: Multi Depot K-Chinese Postman Problem
Directory of Open Access Journals (Sweden)
İbrahim Zeki Akyurt
2015-02-01
Full Text Available In this study, the assignment and routing problem of one of Istanbul’s winter maintenance activities, salt pouring, was scrutinized. The starting point of the study considers the high cost of winter maintenance work, a shrinking assigned budget, high numbers of vehicles and streets to service that the increase in difficulty to solve the problem due to their high numbers. In this respect, the problem was modeled as multi depot k-Chinese postman problem, a type of arc routing problem. This mathematical model was solved by genetic algorithm. For comparison, the current solution, Clarke and Wright Algorithm and Sweep Algorithm were used.
铁路选线设计中常见问题分析%Analysis on Common Problems in Railway Route Selection Design
Institute of Scientific and Technical Information of China (English)
李永贵
2014-01-01
铁路选线的好坏，决定了项目工程的难易程度、工程投资的大小、施工和运营的安全，所以铁路选线是铁路项目设计中最基本、最重要的工作，是影响全局的总体性工作。在中国西南地区，山高谷深、地形地质条件复杂，在此区域修建铁路，工程十分艰巨，更有必要做好铁路选线。笔者经过多年在中国西南山区铁路选线设计工作的经验积累，将铁路选线设计中遇到的环境选线、地质选线、紧坡地段定线、竖曲线与平面圆曲线重合、坡度代数差、坡度使用等问题在文中分别进行了列举分析。铁路选线应根据规范、规定，结合项目沿线的环境和地形地质条件、工程条件、规划及人文等因数，经过多方案的比选，来确定最优的线路方案。%The route selection of railway determines the complexity of project engineering, the amount of project invest-ment as well as the safety of construction and operation, therefore, route selection is the most fundamental and signifi-cant work of project design and it's also a general task that influences the whole project. As Southwest China orea fea-tures high mountains, deep valleys and complex terrains and geological conditions, it's very difficult to build railways here. It is necessary to railway line. With years of experiences in route selection of railways in mountainous regions of Southwest China, problems encountered in selection of railway route are inevitable in the project of railway environmental route selection, geological line selection, tight slope segment alignment, vertical curve and plane circular curve coin-cide, difference in gradients, slope utilization. Route selection should be compliant with regulations and rules to deter-mine the optimal scheme of line,combining to the project along the terrain and geological conditions, construction condi-tions, project planning and cultural factors.
Research of Vehicle Routing Problem Based on Fuzzy Time Windows%基于模糊时间窗的车辆调度问题研究
Institute of Scientific and Technical Information of China (English)
王旭坪; 张凯; 胡祥培
2011-01-01
An increasing number of enterprises are focusing on the vehicle routing problems (VRP) because of expanded logistics support. VRP belongs to typical NP-Hard problems. An enterprise typically spends 25% to 30% of total expenses on vehicle routing problems because they can affect economic efficiency and customer benefits. Therefore, it is important to research VRP and optimize logistics activities.Exiting literature has focused on the vehicle routing problem with hard time and soft time windows. In the VRP with hard time window, the service time must fall within each customer' s time window. Due to the limitation of hard time window and the number of available vehicles, it is often unable to find feasible schedules. To deal with issues pertaining to the violation of time window, researchers have proposed the concept of "soft time window". In the VRP with soft time window, a penalty cost is added once a time window is violated, and the penalty cost is often assumed to be linear with the degree of violation. In some cases, violation of time window does not directly incur any penalty cost, although the satisfaction levels of customers may drop and lead to benefit loss in the long term. In many realistic applications, the hard time window or soft time window does represent customer requirements very well. Under these circumstances, the fuzzy processing of time window can reflect customers' requirements well and truly. Until now, few studies have addressed VRP-with fuzzy time window when the number of vehicle is limited. There are many real-life situations where the number of vehicle is limited, such as logistics distribution, post express and so on. Thus, this paper proposes and solves vehicle routing problems based on the fuzzy time window and a definite number of vehicles. In this paper, a fuzzy membership function is used to characterize customers' satisfaction levels by analyzing customers' practical requirements of the service time window.A multi-objective model
多车场车辆路径问题及混合遗传算法%Multi-depot Vehicle Routing Problem with Hybrid Genetic Algorithm
Institute of Scientific and Technical Information of China (English)
党立伟; 孙小明
2012-01-01
在多车场车辆路径问题中,综合考虑车辆的行驶路程和使用车辆的数量能有效降低配送成本,考虑了这两方面的因素建立了相应的数学模型,运用混合遗传算法进行了求解,并通过实例证明了模型和算法的有效性.%About the multi-depot vehicle routing problem, considering the distance traveled by the vehicle and the number of vehicles together can effectively reduce distribution costs. The corresponding mathematical model by taking the two factors into account is established, solved the model by using genetic algorithms and demonstrate the effectiveness of the model and algorithm by example.
Rose, W. I.; Carn, S. A.; Bluth, G. J.
2002-05-01
We have remote sensing tools to measure volcanic SO2 releases to the atmosphere by volcanoes in terms of kg/s-1 (Rodriguez et al, this session) but to use these data to develop estimates of arc gas release rates to compare with subduction zone rates (subduction factory) is far from straightforward. We have investigated this by considering how to convert the last 20 years of SO2 remote sensing at one Guatemalan volcano to a millenial gas release rate. We have chosen Fuego Volcano as a focal point because much is known about its activity (eruption rates and times) and magma characteristics (composition, intensive parameters, melt inclusion analyses), and because its behavior over the past 500 years consists of frequent eruptions and continual gas emissions. A steady-state rate conversion (20 x 50 = 1000) for Fuego may nonetheless be a basis for considering the whole arc, because it tends to release its volatiles readily. Even with this kind of open vent behavior and abundant helpful lab data we need to use speculative assumptions to get a result. One of these speculations involves excess gas release: Fuego is well known to exhibit this, but data collected in many geochemical studies of Fuego suggest it is highly variable. Lacking understanding of the process which causes the excess leaves us puzzled how to generalize it, even for only one volcanic system. Evaluating the rest of the arc and computing a flux per unit of arc length seems much more difficult than evaluating Fuego alone. Other volcanoes in the arc tend to retain their volatiles (in part for later release) and are therefore not well-estimated from sparse measurements. Another question is whether the relatively constant activity representative exhibited by Fuego is representative of arc activity. Volcanoes with compositional variability and long reposes require integration of robust data over periods much longer than 20 years to determine an accurate rate. Other examples of open vent volcanoes (eg Pacaya
Multi-objective Location-routing Problem in Emergency Logistics as Time Varies%时变条件下应急物流多目标LRP研究
Institute of Scientific and Technical Information of China (English)
赵佳虹
2012-01-01
The multi-objective location-routing problem in emergency logistics aims to decide where to open emergency logistics centers, how much capacity and how to route different types of emergency relief between relief collection nodes, emergency logistics centers and relief demand nodes. Based on the current literatures, considered the diversity of relief demands as time varies as well as the diversity of relief types and emergency logistics centers' minimize treatment amount requirements, taken the route capacity and the emergency logistics centers' capacity with surplus degree as constraints and taken the minimum time and cost as optimal objectives, a multi-objective 0-1 mixed-integer linear programming model for this problem was proposed. Adopted percentage normalization technique to normalize the objective units, the algorithm was designed to solve this model. Through an experimental example, a comparing analysis of the time and cost between this 0-1 mixed-integer linear programming model and the exiting one was conducted. The results proved that the location-routing scheme got from this new model could decrease the cost and time when comparing with the exiting model, and then, this new model would be more in line with the practice of emergency logistics management.%应急物流系统的多目标选址-路径问题主要旨在解决应急物流中心的选址问题、物流中心处理能力的设定问题和各类应急物资车辆运输路径的选择问题.基于既有研究成果,主要考虑时变条件下物资需求的多样性特点,兼顾应急物资类型的多样性特点和物流中心最小处理量要求,以运输路线能力和含有富余度系数的物流中心能力为约束条件,以时间和费用最小化为优化目标,建立了更为完善的多目标0-1混合整数线性规划模型.采用百分比无量纲化技术消除优化目标的量纲,并设计了基于目标规划的模型求解算法.通过算例试验,对比分析了0-1混合整
Memetic algorithm for vehicle routing problem with time windows%基于Memetic算法的带时间窗车辆路径问题研究
Institute of Scientific and Technical Information of China (English)
吴雷; 魏臻; 葛方振
2012-01-01
This paper proposed a Memetic algorithm, which simulated the process of culture evolution, to solve vehicle routing problem with time windows(VRPTW). To convert VRPTW into continuous problem, it designed a real coding method. The memetic algorithm helped the particles which had certain learning capacity accelerate convergence rate by local search strategy. Meanwhile, because of helping some particles which fell into the local optimum escape from local optimum by tabu search, it enhanced the diversity of swarm. The experimental result shows that the proposed algorithm can gel the solution more effectively and it is an effective method for VRPTW.%提出一种模拟文化进化的Memetic算法求解带时间窗的车辆路径问题.设计了一种实数编码方案,将离散的问题转为连续优化问题.采用邻域搜索帮助具备一定学习能力的个体提高寻优速度；采用禁忌搜索帮助部分个体跳出局部最优点,增强全局寻优性能.实验结果表明,该算法可以更有效地求出优化解,是带时间窗车辆路径问题的一种有效求解算法.
Route Repetition and Route Retracing: Effects of Cognitive Aging
Directory of Open Access Journals (Sweden)
Jan Malte Wiener
2012-05-01
Full Text Available Retracing a recently traveled route is a frequent navigation task when learning novel routes or exploring unfamiliar environments. In the present study we utilized virtual environments technology to investigate age-related differences in repeating and retracing a learned route. In the training phase of the experiment participants were guided along a route consisting of multiple intersections each featuring one unique landmark. In the subsequent test phase, they were guided along short sections of the route and asked to indicate overall travel direction (repetition or retracing, the direction required to continue along the route, and the next landmark they would encounter. Results demonstrate age-related deficits in all three tasks. More specifically, in contrast to younger participants, the older participants had greater problems during route retracing than during route repetition. While route repetition can be solved with egocentric response or route strategies, successfully retracing a route requires allocentric processing. The age-related deficits in route retracing are discussed in the context of impaired allocentric processing and shifts from allocentric to egocentric navigation strategies as a consequence of age-related hippocampal degeneration.
A algorithm for the Vehicle Problem
Directory of Open Access Journals (Sweden)
Aziz Ezzatneshan
2010-09-01
Full Text Available In this paper, we propose a hybrid ACO algorithm for solving vehicle routing problem (VRP heuristically in combination with an exact In the basic VRP, geographically scattered customers of known demand are supplied from a single depot by a fleet of identically capacitated vehicles. The intuition of the proposed algorithm is that nodes which are near to each other will probably belong to the same branch of the minimum spanning tree of the problem graph and thus will probably belong to the same route in VRP. Given a clustering of client nodes, the solution is to find a route in these clusters by using ACO with a modified version of transition rule of the ants. At the end of each iteration, ACO tries to improve the quality of solutions by using a local search algorithm, and update the associated weights of the graph arcs.
车辆路径问题：从时间地理学的视角%Vehicle Routing Problem:From a Perspective of Time Geography
Institute of Scientific and Technical Information of China (English)
戚铭尧; 吴涛; 张新
2015-01-01
车辆路径问题具有典型的时空分布特征，受到众多时空约束条件的制约。在车辆路径规划中，综合考虑时间和空间因素是非常必要的。本文从时间地理学这一全新的视角来研究车辆路径问题，提出一套完整的时间地理学分析框架，阐述了时间地理学的基本概念，提出了车辆路径问题中的时空约束、时空路径、时空棱柱、时空可达性、时空距离等概念，并给出了图示或定量化的度量方法。论文提出的时空距离度量方法综合考虑了顾客在空间位置和时间窗口2个方面的特征，可更科学地判定顾客之间的“邻近性”。论文通过设计一种求解大规模软时间窗车辆路径问题的算法，证明了时空距离的价值，并展望了时间地理学在求解动态车辆路径规划问题、移动设施路径规划问题等方面的应用。本文的贡献在于，通过时间地理学所提供的一系列概念和方法，实现了在统一的框架下同时考虑车辆路径问题（VRP）的时间和空间特征的构想，挖掘了传统时间地理学理论在车辆路径领域中的应用潜力，这将有利于更快或者更好地求解VRP问题。%Vehicle routing problem (VRP) has typical characteristics of space-time distribution, thus it is influ-enced by constrains of space-time conditions. It is necessary to take the space and time factors comprehensively into the consideration of vehicle routing planning. In this paper, we proposed a new perspective to investigate ve-hicle routing problem and introduced a complete analytic framework from the aspects of time geography. Fol-lowed by the introduction of the fundamental theory of time geography, concepts including space-time con-straints, space-time path, space-time prism, space-time accessibility, and space-time distance are illustrated in the context of VRP. Meanwhile, the diagrammatic and metric methods of these concepts are also provided. In
International Nuclear Information System (INIS)
The arc saw is one of the key components of the Contaminated Equipment Volume Reduction (CEVR) Program. This report describes the progress of the arc saw from its inception to its current developmental status. History of the arc saw and early contributors are discussed. Particular features of the arc saw and their advantages for CEVR are detailed. Development of the arc saw including theory of operation, pertinent experimental results, plans for the large arc saw and advanced control systems are covered. Associated topics such as potential applications for the arc saw and other arc saw installations in the world is also touched upon
Route optimization model for strike aircraft
Lee, Steve H. K.
1995-01-01
A model is designed and implemented to construct a 'flyable,' least- risk route for strike aircraft from takeoff to target, through enemy radars, in a defined area of operations. A network is fust constructed by discretizing the airspace into a three-dimensional grid of nodes and then connecting adjacent nodes with arcs. A shortest-path model in this network is then constructed with arc lengths that are a function of the probability of detection by radars monitoring t...
Optimization of OSPF Routing in IP Networks
Bley, Andreas; Fortz, Bernard; Gourdin, Eric; Holmberg, Kaj; Klopfenstein, Olivier; Pióro, Michał; Tomaszewski, Artur; Ümit, Hakan
The Internet is a huge world-wide packet switching network comprised of more than 13,000 distinct subnetworks, referred to as Autonomous Systems (ASs) autonomous system AS . They all rely on the Internet Protocol (IP) internet protocol IP for transport of packets across the network. And most of them use shortest path routing protocols shortest path routing!protocols , such as OSPF or IS-IS, to control the routing of IP packets routing!of IP packets within an AS. The idea of the routing is extremely simple — every packet is forwarded on IP links along the shortest route between its source and destination nodes of the AS. The AS network administrator can manage the routing of packets in the AS by supplying the so-called administrative weights of IP links, which specify the link lengths that are used by the routing protocols for their shortest path computations. The main advantage of the shortest path routing policy is its simplicity, allowing for little administrative overhead. From the network engineering perspective, however, shortest path routing can pose problems in achieving satisfactory traffic handling efficiency. As all routing paths depend on the same routing metric routing!metric , it is not possible to configure the routing paths for the communication demands between different pairs of nodes explicitly or individually; the routing can be controlled only indirectly and only as a whole by modifying the routing metric. Thus, one of the main tasks when planning such networks is to find administrative link weights that induce a globally efficient traffic routing traffic!routing configuration of an AS. It turns out that this task leads to very difficult mathematical optimization problems. In this chapter, we discuss and describe exact integer programming models and solution approaches as well as practically efficient smart heuristics for such shortest path routing problems shortest path routing!problems .
Generalized hyperfocused arcs in $PG(2,p)$
Blokhuis, A Aart; Marino, G.; Mazzocca, F.
2013-01-01
A {\\em generalized hyperfocused arc} $\\mathcal H $ in $PG(2,q)$ is an arc of size $k$ with the property that the $k(k-1)/2$ secants can be blocked by a set of $k-1$ points not belonging to the arc. We show that if $q$ is a prime and $\\mathcal H$ is a generalized hyperfocused arc of size $k$, then $k=1,2$ or 4. Interestingly, this problem is also related to the (strong) cylinder conjecture [Ball S.: The polynomial method in Galois geometries, in Current research topics in Galois geometry, Chap...
Accident Emergency Response And Routing Software (AERARS using Genetic Algorithm
Directory of Open Access Journals (Sweden)
Naveen Ramachandran,
2011-07-01
Full Text Available AERARS is a response and routing software for accident emergency requirement. A method has been proposed in this project for using a genetic algorithm to find the shortest route between a source and adestination. It make use of genetic algorithms ability to search the opt solution from the population helping to solve spatially addressed problem. The numbers of accident spots are plotted in ArcGISenvironment and ten major accident spots are identified. The software package is designed with closest facility estimation and shortest route generation along with other basic software facilities in Visual Basic environment. Genetic algorithm provided a great optimality to the solutions. The closest facility tool helps to estimate the nearest hospital, ambulance, police station and fire station. The shortest route estimation tool generates shortest path between a locations to the hospital or ambulance spot. The various risk zonesare assessed and more safety measures can be taken to reduce the frequency of accident. The software efficiency can be further increased by incorporating GPS and satellite technology.
Stochastic Vehicle Routing with Recourse
Goertz, Inge Li; Saket, Rishi
2012-01-01
We study the classic Vehicle Routing Problem in the setting of stochastic optimization with recourse. StochVRP is a two-stage optimization problem, where demand is satisfied using two routes: fixed and recourse. The fixed route is computed using only a demand distribution. Then after observing the demand instantiations, a recourse route is computed -- but costs here become more expensive by a factor lambda. We present an O(log^2 n log(n lambda))-approximation algorithm for this stochastic routing problem, under arbitrary distributions. The main idea in this result is relating StochVRP to a special case of submodular orienteering, called knapsack rank-function orienteering. We also give a better approximation ratio for knapsack rank-function orienteering than what follows from prior work. Finally, we provide a Unique Games Conjecture based omega(1) hardness of approximation for StochVRP, even on star-like metrics on which our algorithm achieves a logarithmic approximation.
Institute of Scientific and Technical Information of China (English)
王科峰; 叶春明
2013-01-01
A general outline of various types of vehicle routing problems in the field of reverse logistics was given.The vehicle routing problems were divided into two classes,i.e.the problem of single demand and double demands,according to the demand characteristic of the customer node.The vehicle routing problem with simultaneous delivery and pickup (VRPSDP) and the vehicle routing problem with split deliveries and pickups (SVRPPD) were called as the vehicle routing problem with nodes of double demands (VRPNDD).Their definitions and mathematic models were given.Then as the preliminary work for designing the heuristics,some constitutive properties of the solution for the VRPNDD were investigated.The difference in properties of optimal solutions between SVRPPD and SDVRP (the vehicle routing problem with split delivery) was illustrated,and a theorem was proved to show the significance of the heuristics' improving on cost saving analysis of SVRPPD relative to VRPSDP.%概括介绍了逆向物流领域中的各类车辆路径问题,将问题按照节点的需求类型分为节点单需求以及具有双重需求两个大类.按照节点的需求类型,将同时送取货(VRPSDP)、集送货需求可拆分车辆路径问题(SVRPPD)统称为节点具有双重需求车辆路径问题(VRPNDD).文中首先给出了它们的定义及数学模型.接着,作为设计求解问题启发式算法的前期工作,对VRPNDD问题解的结构方面的一些性质进行了分析证明.最后,举例说明了SVRPPD与送货需求可拆分车辆路径问题最优解性质方面的差异,并通过定理证明说明了SVRPPD,VRPSDP启发式算法的改良对于SVRPPD相对VRPSDP节省成本百分比研究的意义.
Blind Alley Aware ACO Routing Algorithm
Yoshikawa, Masaya; Otani, Kazuo
2010-10-01
The routing problem is applied to various engineering fields. Many researchers study this problem. In this paper, we propose a new routing algorithm which is based on Ant Colony Optimization. The proposed algorithm introduces the tabu search mechanism to escape the blind alley. Thus, the proposed algorithm enables to find the shortest route, even if the map data contains the blind alley. Experiments using map data prove the effectiveness in comparison with Dijkstra algorithm which is the most popular conventional routing algorithm.
Advances in optimal routing through computer networks
Paz, I. M.
1977-01-01
The optimal routing problem is defined. Progress in solving the problem during the previous decade is reviewed, with special emphasis on technical developments made during the last few years. The relationships between the routing, the throughput, and the switching technology used are discussed and their future trends are reviewed. Economic aspects are also briefly considered. Modern technical approaches for handling the routing problems and, more generally, the flow control problems are reviewed.
BASIC THEORY AND METHOD OF WELDING ARC SPECTRAL INFORMATION
Institute of Scientific and Technical Information of China (English)
Li Junyue; Li Zhiyong; Li Huan; Xue Haitao
2004-01-01
Arc spectral information is a rising information source which can solve many problems that can not be done with arc electric information and other arc information.It is of important significance to develop automatic control technique of welding process.The basic theory and methods on it play an important role in expounding and applying arc spectral information.Using concerned equation in plasma physics and spectrum theory,a system of equations including 12 equations which serve as basic theory of arc spectral information is set up.Through analyzing of the 12 equations,a basic view that arc spectral information is the reflection of arc state and state variation,and is the most abundant information resource reflecting welding arc process is drawn.Furthermore,based on the basic theory,the basic methods of test and control of arc spectral information and points out some applications of it are discussesed.
物流配送路径延伸问题两阶段寻优策略算法%A Two-stage Optimization Algorithm for the Distribution Route Extension Problem
Institute of Scientific and Technical Information of China (English)
何方
2012-01-01
首先根据实际路径资料构建非完全有向图,利用Dijkstra算法得到任意两点之间的最优路径,根据要求虚拟合并或删除非目的地节点,对图形进行简化,重新构造出包含所有有效路径信息和有效节点的非完全有向图,在此基础上运用非完全有向图TSP问题的求解方法进行路径优化.通过示例验证了该算法对于解决物流配送中的此类特定问题是有效的.%In this paper,a non-complete directed graph is drawn according to practical route information and materials and the Dijkstra algorithm is used to calculate the shortest path between any given two points. Then the graph is simplified through virtual combining or deleting the non-destination points as is required and restructured into a non-complete directed graph containing information concerning all feasible routes and points, on the basis of which a solution to the Traveling Salesman Problem of the graph is developed to optimize the distribution routing. Finally a numerical example is used to illustrate the validity of this algorithm in distribution routing problems.
Gas arc constriction for plasma arc welding
McGee, William F. (Inventor); Rybicki, Daniel J. (Inventor)
1994-01-01
A welding torch for plasma arc welding apparatus has an inert gas applied circumferentially about the arc column externally of the constricting nozzle so as to apply a constricting force on the arc after it has exited the nozzle orifice and downstream of the auxiliary shielding gas. The constricting inert gas is supplied to a plenum chamber about the body of the torch and exits through a series of circumferentially disposed orifices in an annular wall forming a closure at the forward end of the constricting gas plenum chamber. The constricting force of the circumferential gas flow about the arc concentrates and focuses the arc column into a more narrow and dense column of energy after exiting the nozzle orifice so that the arc better retains its energy density prior to contacting the workpiece.
Solving Stochastic Demand Inventory Routing Problem with Hard Time Windows%求解硬时间窗约束下随机需求库存-路径问题的优化算法
Institute of Scientific and Technical Information of China (English)
赵达; 李军; 马丹祥; 李妍峰
2014-01-01
The Stochastic Demand Inventory Routing Problem (SDIRP)is a kind of typical NP-hard problem.To consider the coordination and optimization problem of inventory and distribution in the supply chain is the key to implementing vendor managed inventory .This paper explores the stochastic demand IRP with hard time windows ( SDIRPHTW) , and decomposes SDIRPHTW into two sub-problems: stochastic inventory routing problem with direct distribution and vehicle routing problem with hard time windows .Then, with the objective to minimizing the system cost and the number of vehicles , we present a heuristic algorithm based on ( s,S) inventory policy and modified C-W saving algorithm , and analyses the efficiency of the algorithm through a numerical example .%随机需求库存-路径问题（ Stochastic Demand Inventory Routing Problem ， SDIRP）即考虑随机需求环境下供应链中库存与配送的协调优化问题，是实施供应商管理库存策略过程中的关键所在，也是典型的NP难题之一。文章以具有硬时间窗约束的随机需求库存-路径问题（ Stochastic Demand Inventory Routing Problem with Hard Time Windows ， SDIRPHTW）为研究对象，将SDIRPHTW分解为直接配送的随机库存-路径问题和具有硬时间窗约束的路径优化问题两个子问题，并以最小化系统运行成本和用车数量为目标，设计了一个基于（ s，S）库存策略和修正C-W节约法的启发式算法。最后，通过相应的数值算例验证了算法的有效性。
Classification of Dynamic Vehicle Routing Systems
DEFF Research Database (Denmark)
Larsen, Allan; Madsen, Oli B.G.; Solomon, Marius M.
2007-01-01
to classify dynamic vehicle routing systems. Methods for evaluation of the performance of algorithms that solve on-line routing problems are discussed and we list some of the most important issues to include in the system objective. Finally, we provide a three-echelon classification of dynamic vehicle routing......This chapter discusses important characteristics seen within dynamic vehicle routing problems. We discuss the differences between the traditional static vehicle routing problems and its dynamic counterparts. We give an in-depth introduction to the degree of dynamism measure which can be used...
The Abundance of Large Arcs From CLASH
Xu, Bingxiao; Postman, Marc; Meneghetti, Massimo; Coe, Dan A.; Clash Team
2015-01-01
We have developed an automated arc-finding algorithm to perform a rigorous comparison of the observed and simulated abundance of large lensed background galaxies (a.k.a arcs). We use images from the CLASH program to derive our observed arc abundance. Simulated CLASH images are created by performing ray tracing through mock clusters generated by the N-body simulation calibrated tool -- MOKA, and N-body/hydrodynamic simulations -- MUSIC, over the same mass and redshift range as the CLASH X-ray selected sample. We derive a lensing efficiency of 15 ± 3 arcs per cluster for the X-ray selected CLASH sample and 4 ± 2 arcs per cluster for the simulated sample. The marginally significant difference (3.0 σ) between the results for the observations and the simulations can be explained by the systematically smaller area with magnification larger than 3 (by a factor of ˜4) in both MOKA and MUSIC mass models relative to those derived from the CLASH data. Accounting for this difference brings the observed and simulated arc statistics into full agreement. We find that the source redshift distribution does not have big impact on the arc abundance but the arc abundance is very sensitive to the concentration of the dark matter halos. Our results suggest that the solution to the "arc statistics problem" lies primarily in matching the cluster dark matter distribution.
节点具有双重需求的车辆路径问题及其性质%THE VEHICLE ROUTING PROBLEM AND IT'S PROPERTY WITH NODES HAVING DOUBLE DEMANDS
Institute of Scientific and Technical Information of China (English)
王科峰; 叶春明; 唐国春
2011-01-01
Based on the original definition of the Simultaneous Pickup and Delivery Vehicle Routing Problem, the relationship between the vehicle's capacity and the demand of the node was expanded into the case that the later was permitted to be greater than the former. Then the reducibility of the Simultaneous Pickup and Delivery Vehicle Routing Problem and the Split Vehicle Routing Problem with Pickup and Delivery was studied. The reducibility definitions of these two problems were given. It follows that when the distance satisfies the triangle inequality and the vehicle's capacity is equal to 1, the Split Vehicle Routing Problem with Pickup and Delivery is reducible and equivalent to the Simultaneous Pickup and Delivery Vehicle Routing Problem, and that when the vehicle's capacity is greater than or equal to 2, these two problems were irreducible. Then the complexity of these two problems is proved when the vehicle's capacity was equal to 1 and greater than or equal to 3. Finally an example shows the obvious structural difference of the optimal solutions between the Split Vehicle Routing Problem with Pickup and Delivery and the Split Vehicle Routing Problem.%在原有同时收发车辆路径问题定义的基础上,将节点需求与车辆容量的关系拓展到允许节点需求大于车辆容量的情形.接着对集送货需求可拆分车辆路径问题和同时收发车辆路径问题的可简化性进行了研究.给出了两类问题可简化的定义,并得到了当距离满足三角不等式,车辆容量为1时集送货需求可拆分车辆路径问题可简化并与同时收发车辆路径问题等价,而当容量大于等于2时两类问题都不可以简化的结论.同时也对两类问题当车辆容量等于1时,以及大于等于3时的计算复杂性给出了证明.最后通过一个实例说明了集送货需求可拆分车辆路径问题与同时收发车辆路径问题在最优解的结构性质方面存在着明显差异.
Multipath Routing Protocol for Effective Local Route Recovery in Mobile Ad hoc Network
Directory of Open Access Journals (Sweden)
S. K. Srivatsa
2012-01-01
Full Text Available Problem statement: In mobile ad hoc networks, frequent mobility during the transmission of data causes route failure which results in route rediscovery. In this, we propose multipath routing protocol for effective local route recovery in Mobile Ad hoc Networks (MANET. In this protocol, each source and destination pair establishes multiple paths in the single route discovery and they are cached in their route caches. Approach: The cached routes are sorted on the basis of their bandwidth availability. In case of route failure in the primary route, a recovery node which is an overhearing neighbor, detects it and establishes a local recovery path with maximum bandwidth from its route cache. Results: By simulation results, we show that the proposed approach improves network performance. Conclusion: The proposed route recovery management technique prevents the frequent collision and degradation in the network performance.
Linear Network Fractional Routing
Directory of Open Access Journals (Sweden)
S.ASOKAN,
2011-07-01
Full Text Available A Network is a finite directed acyclic graph with source messages from a fixed alphabet and message demands at sink nodes. Linear Programming is an algorithm design method. It can be used whenthe solution to a problem can be viewed as the result of a sequence of decisions. The Linear Programming model for the network problem where in every variable has a value one or zero. The problem is todetermine a method of transmitting the messages through the network such that all sink demands are satisfied. We will prove fractional routing capacity for some solvable network using Linear Programmingmodel.
Whealton, John H.; Tsai, Chin-Chi
2003-05-27
A spark plug device includes a structure for modification of an arc, the modification including arc rotation. The spark plug can be used in a combustion engine to reduce emissions and/or improve fuel economy. A method for operating a spark plug and a combustion engine having the spark plug device includes the step of modifying an arc, the modifying including rotating the arc.
Institute of Scientific and Technical Information of China (English)
汤中明
2013-01-01
A supply chain composed of many vendors, one third-party logistics (TPL) , and one manufacturer is addressed. It assumes that, in such a supply chain, it integrates vendor-managed inventory ( VMI) and TPL. For such a supply chain, inventory routing problem under centralized control is studied. How to make the decision of replenishing and vehicle routing plan for suppliers and TPL is a challenging problem. Based on rolling plan period, a new inventory routing model is developed. With the NP-complete nature of the inventory routing problem, a four-step heuristic algorithm based on simulated annealing is presented. The feasibility and effectiveness of the proposed heuristic algorithm is testified by a numerical example.%以“多供应商,单TPL,单制造商”供应链网络为研究环境,研究了集中控制VMI&TPL模式下的库存运输集成优化问题,旨在为供应商和TPL提供补货决策和车辆路线计划.基于滚动计划期,构建了库存运输集成计划模型.鉴于该模型问题是一个NPC问题,提出了基于模拟退火遗传算法的四步骤启发式算法.算例分析结果表明该启发式算法是有效可行的.
Sensor Control of Robot Arc Welding
Sias, F. R., Jr.
1983-01-01
The potential for using computer vision as sensory feedback for robot gas-tungsten arc welding is investigated. The basic parameters that must be controlled while directing the movement of an arc welding torch are defined. The actions of a human welder are examined to aid in determining the sensory information that would permit a robot to make reproducible high strength welds. Special constraints imposed by both robot hardware and software are considered. Several sensory modalities that would potentially improve weld quality are examined. Special emphasis is directed to the use of computer vision for controlling gas-tungsten arc welding. Vendors of available automated seam tracking arc welding systems and of computer vision systems are surveyed. An assessment is made of the state of the art and the problems that must be solved in order to apply computer vision to robot controlled arc welding on the Space Shuttle Main Engine.
Research on the route of substation patrol based on the Postman Problem%基于邮递员问题的变电站巡视路线探究
Institute of Scientific and Technical Information of China (English)
彭光超
2014-01-01
本文主要基于无向图的传统邮递员问题研究变电站巡视路线规划问题。以某变电站为实例，应用奇偶点作业法研究如何制定巡视路线。最后通过分析比较表明，利用路径规划方法制定变电站巡视路线，可以节约时间及人力成本，效果显著。%This paper mainly based on undirected graph of the traditional substation postman problem patrol route planning problem. In a substation as an example,research on the application of parity operation method how to formulate the patrol route.Finally,through the analysis and comparison show that,by using the method of path planning for substation patrol route,can save time and manpower cost,the effect is significant.
Incorporation of crust at the Lesser Antilles arc
Davidson, J. P.; Bezard, R. C.
2012-12-01
Most convergent margin magmas exhibit geochemical characteristics of continental crust, incorporated via subduction of continental sediment into the arc source (mantle wedge) or via assimilation of continental crust by arc magmas en route to surface. Resolving which of these processes dominate at a given arc is important in avoiding the circularity of the question of the origin of the continental crust. The Lesser Antilles is built on oceanic lithosphere so in principle any crustal signature has been introduced via sediment subduction. Geochemical variations in magmas along the arc have been matched with the variations displayed in sediments outboard of the trench 1 . At about the same time, similarly comprehensive data sets were produced from along the Lesser Antilles, arguing that much of the geochemical diversity reflected crustal contamination rather than source contamination 2. These claims were based on; 1) correlations between isotopic ratios and indices of differentiation, 2) high delta18O, which argues for extensive interaction with material that has interacted with water at low T and finally the observation that the highest Pb isotope ratios in the lavas actually exceed the highest seen in the sediments. The latter problem has now been solved since a wider range of sediments have now been examined, with a section of black shales exhibiting remarkably radiogenic Pb isotopes 3 . We have re-examined the origin of geochemical variations by comparing two specific volcanoes, Mt Pelee in the centre of the arc and The Quill in the north 4. The idea is to explore differentiation trends at a given volcano, and back project them to reasonable primitive magma compositions. In that way we can account for geochemical effects resulting from differentiation, and focus on source variations (contributions from slab to wedge along the Antilles). From this we conclude that 1) both suites differentiate largely by amphibole-plag fractionation, along with contamination by the
铁路货运机车动态周转与运用优化方法研究%Method for Optimization of Freight Locomotive Scheduling and Routing Problem
Institute of Scientific and Technical Information of China (English)
王龙; 马建军; 林柏梁; 陈雷; 温旭红
2014-01-01
Optimization of formulation of freight locomotive scheduling and routing plans from the angle of dy-namic states is of great significance to improving the daily working efficiency of locomotives and to satisfying requirements of traction power of trains.In this paper,the continuous multi-level time-space network applica-ble to any locomotive run was constructed in comprehensive consideration of locomotive servicing work,repair and stand-by etc in locomotive shunting and with figuring out the correct and efficient locomotive daily working diagram as the objective.Thus,the freight locomotive scheduling and routing problem was transformed into route choice of freight locomotives in the time-space network.Applying the thought of path-based model,sets of available routes were generated for any of locomotives,the model for route choice was constructed and the genetic algorithm was used to solve the model.Therefore,a set of theoretical methods for optimization of freight locomotive scheduling and routing problem was formed.Finally,a numerical example was given to veri-fy the rationality and effectiveness of the proposed model and algorithm.%从动态角度出发优化编制铁路货运机车周转与运用计划对于提高机车日常工作效率、及时配备牵引动力具有重要意义。本文以编制高效的日计划机车周转图为目标，综合兼顾机车调度过程中整备、检修、备用等因素，针对任意机车交路建立多层次连续型时空网络，从而将铁路货运机车动态周转与运用问题转化为时空网络中机车走行径路的选择问题。采用弧-路模型思想为其中任意一台机车生成可选径路集，构建相应的径路优化模型，应用遗传算法对模型求解，形成一套解决铁路货运机车动态周转与运用问题的理论优化方法。最后，通过算例验证模型与算法的合理性及有效性。
ROUTING AND WAVELENGTH ASSIGNMENT ALGORITHMS BASED ON EQUIVALENT NETWORKS
Institute of Scientific and Technical Information of China (English)
Qi Xiaogang; Liu Lifang; Lin Sanyang
2006-01-01
In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assignment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wavelength-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimization of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms' feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.
Energy Technology Data Exchange (ETDEWEB)
Bouvier, A. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches; Trenty, L.; Guillot, J.B. [Ecole Centrale de Paris, Laboratoire EM2C. CNRS, 92 - Chatenay-Malabry (France); Delalondre, C. [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches
1997-12-31
This paper presents the modeling of a transferred electric arc inside a bath of melted metal. After a recall of the context of the study, the problem of the modeling, which involves magnetohydrodynamic coupling inside the arc and the bath, is described. The equations that govern the phenomena inside the arc and the bath are recalled and the approach used for the modeling of the anode region of the arc is explained using a 1-D sub-model. The conditions of connection between arc and bath calculations are explained and calculation results obtained with a 200 kW laboratory furnace geometry are presented. (J.S.) 8 refs.
CLASSIFICATION OF FOREST ROADS AND DETERMINATION OF ROUTE USING GEOGRAPHIC INFORMATION SYSTEM
Directory of Open Access Journals (Sweden)
Fabrício Silva
2016-04-01
Full Text Available ABSTRACT Geographic Information System (GIS is an indispensable software tool in forest planning. In forestry transportation, GIS can manage the data on the road network and solve some problems in transportation, such as route planning. Therefore, the aim of this study was to determine the pattern of the road network and define transport routes using GIS technology. The present research was conducted in a forestry company in the state of Minas Gerais, Brazil. The criteria used to classify the pattern of forest roads were horizontal and vertical geometry, and pavement type. In order to determine transport routes, a data Analysis Model Network was created in ArcGIS using an Extension Network Analyst, allowing finding a route shorter in distance and faster. The results showed a predominance of horizontal geometry classes average (3 and bad (4, indicating presence of winding roads. In the case of vertical geometry criterion, the class of highly mountainous relief (4 possessed the greatest extent of roads. Regarding the type of pavement, the occurrence of secondary coating was higher (75%, followed by primary coating (20% and asphalt pavement (5%. The best route was the one that allowed the transport vehicle travel in a higher specific speed as a function of road pattern found in the study.
Khan, D; Samadder, S R
2016-07-01
Collection of municipal solid waste is one of the most important elements of municipal waste management and requires maximum fund allocated for waste management. The cost of collection and transportation can be reduced in comparison with the present scenario if the solid waste collection bins are located at suitable places so that the collection routes become minimum. This study presents a suitable solid waste collection bin allocation method at appropriate places with uniform distance and easily accessible location so that the collection vehicle routes become minimum for the city Dhanbad, India. The network analyst tool set available in ArcGIS was used to find the optimised route for solid waste collection considering all the required parameters for solid waste collection efficiently. These parameters include the positions of solid waste collection bins, the road network, the population density, waste collection schedules, truck capacities and their characteristics. The present study also demonstrates the significant cost reductions that can be obtained compared with the current practices in the study area. The vehicle routing problem solver tool of ArcGIS was used to identify the cost-effective scenario for waste collection, to estimate its running costs and to simulate its application considering both travel time and travel distance simultaneously.
Khan, D; Samadder, S R
2016-07-01
Collection of municipal solid waste is one of the most important elements of municipal waste management and requires maximum fund allocated for waste management. The cost of collection and transportation can be reduced in comparison with the present scenario if the solid waste collection bins are located at suitable places so that the collection routes become minimum. This study presents a suitable solid waste collection bin allocation method at appropriate places with uniform distance and easily accessible location so that the collection vehicle routes become minimum for the city Dhanbad, India. The network analyst tool set available in ArcGIS was used to find the optimised route for solid waste collection considering all the required parameters for solid waste collection efficiently. These parameters include the positions of solid waste collection bins, the road network, the population density, waste collection schedules, truck capacities and their characteristics. The present study also demonstrates the significant cost reductions that can be obtained compared with the current practices in the study area. The vehicle routing problem solver tool of ArcGIS was used to identify the cost-effective scenario for waste collection, to estimate its running costs and to simulate its application considering both travel time and travel distance simultaneously. PMID:27207771
Capacitated Vehicle Routing Problem Based on Improved Immune Genetic Algorithm%基于改进免疫算法的有能力约束车辆路径问题
Institute of Scientific and Technical Information of China (English)
梁勤欧
2011-01-01
针对遗传算法、免疫遗传算法在解决车辆路径问题(VRP)中存在的问题与不足,提出了一种改进免疫遗传算法.该算法主要在检查个体的多样性程度方面进行了简化,运用多样性指数阈值控制种群个体的多样性.通过有能力约束VRP的实验验证了新算法,得到了满意的效果.%There are some problems when genetic algorithm and immune genetic algorithm are used to solve Vehicle Routing Problem ( VRP). An improved immune genetic algorithm was proposed to overcome these disadvantages. The characteristic of the improved immune genetic algorithm is that the diversity detection method was simplified and population diversity was controlled by threshold determination method. Then a simple example of capacitated vehicle routing problem was conducted, and an improved immune genetic algorithm and perfect results were obtained.
Aula, Matti; Mäkinen, Ari; Fabritius, Timo
2014-01-01
Control of chromium oxidation in the electric arc furnace (EAF) is a significant problem in stainless steel production due to variations of the chemical compositions in the EAF charge. One potential method to control chromium oxidation is to analyze the emission spectrum of the electric arc in order to find indicators of rising chromium content in slag. The purpose of this study was to determine if slag composition can be gained by utilizing electric arc emission spectra in the laboratory environment, despite electric arc voltage fluctuations and varying slag composition. The purpose of inducing voltage fluctuation was to simulate changes in the industrial EAF process. The slag samples were obtained from Outokumpu Stainless Oy Tornio Works, and three different arc currents were used. The correlation analysis showed that the emission spectra offer numerous peak ratios with high correlations to the X-ray fluorescence-measured slag CrO(x)/FeO(x) and MnO/SiO2 ratios. These ratios are useful in determining if the reduction agents have been depleted in the EAF. The results suggest that analysis of laboratory-scale electric arc emission spectra is suitable for indicating the high CrO(x) or MnO content of the slag despite the arc fluctuations. Reliable analysis of other slag components was not successful.
求解带时间窗车辆路径问题的混合智能算法%Hybrid intelligent algorithm for vehicle routing problem with time windows
Institute of Scientific and Technical Information of China (English)
孙小军
2015-01-01
Based on cuckoo search algorithm and partheno-genetic algorithm,a hybrid intelligent algorithm is designed to solve the vehicle routing problem with time windows.Firstly,this algorithm analyzes the locations of customers by clustering method,and then,forms the optimal route for the divided areas.This hybrid intelligent algorithm not only improves the operation of the cuckoo search algorithm,which is to randomly change the whole location of the cuckoo nest when the cuckoo eggs are found by the nest's master,but also accelerates the search speed of optimal delivery route by using partheno-genetic algorithm.In addition,the computational complexities of this hybrid intelligent algorithm and cuckoo search algorithm are analyzed and compared.Finally,according to test results under ISO standard test collection-Benchmark Problems,it is verified that this hybrid intelligent algorithm is an effective method in solving the vehicle routing problem with time windows.%基于布谷鸟搜索算法和单亲遗传算法，设计了一种求解带时间窗车辆路径问题的混合智能算法。该算法首先对客户位置进行聚类分析，然后再进行各区域的路径优化。混合智能算法不仅改进了布谷鸟搜索算法中当鸟卵被鸟窝主人发现后需要随机改变整个鸟窝位置的操作，同时引入的单亲遗传算法加快了最优配送路线的搜索速度。分析和比较了混合智能算法与布谷鸟搜索算法的计算复杂度。最后采用国际通用标准测试集 Benchmark Problems 进行测试。结果显示，混合智能算法是求解带时间窗车辆路径问题的一种有效算法。
Fast Arc-Annotated Subsequence Matching in Linear Space
DEFF Research Database (Denmark)
Bille, Philip; Gørtz, Inge Li
2010-01-01
An arc-annotated string is a string of characters, called bases, augmented with a set; of pairs, called arcs, each connecting two bases. Given arc-annotated strings P and Q the arc-preserving subsequence problem is to determine if P can be obtained from Q by deleting bases from Q. Whenever a base...... is deleted any arc with an endpoint in that base is also deleted. Arc-annotated strings where the arcs are "nested" are a natural model of RNA molecules that captures both the primary and secondary structure of these. The arc-preserving subsequence problem for nested arc-annotated strings is basic primitive...... the previous time bound while significantly reducing the space from a quadratic term to linear. This is essential to process large RNA molecules where the space is a likely to be a bottleneck. To obtain our result we introduce several novel ideas which may be of independent interest for related problems on arc-annotated...
Wire + Arc Additive Manufacturing
Williams, Stewart W.; Martina, Filomeno; Addison, Adrian C.; Ding, Jialuo; Pardal, Goncalo; Colegrove, Paul A.
2016-01-01
Depositing large components (>10 kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to ...
Stochastic vehicle routing: from theory to practice
Weyland, Dennis; Gambardella, Luca Maria; Montemanni, Roberto
2013-01-01
In this thesis we discuss practical and theoretical aspects of various stochastic vehicle routing problems. These are combinatorial optimization problems related to the field of transportation and logistics in which input data is (partially) represented in a stochastic way. More in detail, we focus on two-stage stochastic vehicle routing problems and in particular on so-called a priori optimization problems. The results are divided into a theoretical part and a practical part. In fact, the ...
Arif, Mohammad
2012-01-01
Mobile ad hoc network (MANET) is a collection of wireless mobile nodes. It dynamically forms a temporary network without using any pre existing network infrastructure or centralized administration i.e. with minimal prior planning. All nodes have routing capabilities and forward data packets to other nodes in multi-hop fashion. As the network is dynamic, the network topology continuously experiences alterations during deployment. The biggest challenge in MANETs is to find a path between communicating nodes. The considerations of the MANET environment and the nature of the mobile nodes create further complications which results in the need to develop special routing algorithms to meet these challenges. Swarm intelligence, a bio-inspired technique, which has proven to be very adaptable in other problem domains, has been applied to the MANET routing problem as it forms a good fit to the problem. In ant societies the activities of the individuals are not regulated by any explicit form of centralized control but ar...
BASIC THEORY AND APPLICATIONS OF WELDING ARC SPECTRAL INFORMATION
Institute of Scientific and Technical Information of China (English)
LI Junyue; XUE Haitao; LI Huan; SONG Yonglun
2007-01-01
Welding arc spectral information is a rising welding Information source. In some occasion, it can reflect many physical phenomena of welding process and solve many problems that cannot be done with arc electric information, acoustic information and other arc information. It is of important significance in developing automatic control technique of welding process and other similar process. Many years study work on welding arc spectral information of the anthor are discussed from three aspects of theory, method and application. Basic theory, view and testing methods of welding arc spectral information has been put forward. In application aspects, many applied examples, for example, monitoring of harmful gases in arc (such as hydrogen and nitrogen) with the method of welding arc spectral information; welding arc spectral imaging of thc welding pool which is used in automatic seam tracking; controlling of welding droplet transfer with welding arc spectral information and so on, are introduced. Especially, the successful application in real time controlling of welding droplet transfer in pulsed GMAW is introduced too. These application examples show that the welding arc spectral information has great applied significance and development potentialities. These content will play an important role in applying and spreading welding arc spectral information technology.
MILITARY MULTI-HOP ROUTING PROTOCOL
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Military tactical network is one of the most important applications of ad hoc network. Currently the existing routing protocols are put forward based on the simple and universal network model which has the ability of multi-hop routing but cannot work efficiently in the special military applications. The narrow bandwidth and limited energy of the wireless network make general routing protocols seem to be more redundant.In order to satisfy military needs properly, this letter makes a detailed analysis of physical nodes and traffic distribution in military network, uses cross-layer design concept for reference, combines traffic characteristic of application layer with routing protocol design. It categorized routing problem as crucial routes and non-crucial routes which adopted separate maintenance methods. It not only realizes basic transmission function but also works efficiently. It is quite fit for military application.
Institute of Scientific and Technical Information of China (English)
王振; 王宁会; 李铁; 曹勇
2012-01-01
A three dimensional steady-state magnetohydrodynamic model is developed for the arc plasma in a DC submerged electric arc furnace for the production of fused MgO. The arc is generated in a small semi-enclosed space formed by the graphite electrode, the molten bath and unmelted raw materials. The model is first used to solve a similar problem in a steel making furnace, and the calculated results are found to be in good agreement with the published measurements. The behavior of arcs with different arc lengths is also studied in the furnace for MgO production. From the distribution of the arc pressure on the bath surface it is shown that the arc plasma impingement is large enough to cause a crater-like depression on the surface of the MgO bath. The circulation of the high temperature air under the electrode may enhance the arc efficiency, especially for a shorter arc.
Arc deflection model and arc direction control for DC arc furnace
Institute of Scientific and Technical Information of China (English)
Liping Wei; Huang Zhou; Huade Li; Yuanhang Zhou
2004-01-01
Based on the analysis of three-dimensional power conductor for DC arc furnace, the electric arc deflection model was set up and the control system of the arc direction was configured. According to the bus bar distribution at the bottom electrodes cooled by water, the arc direction control principle and its configuration were described. The simulation results show that the control system can restrain the electric arc deflection and control the arc direction.
Institute of Scientific and Technical Information of China (English)
高明霞; 贺国光
2011-01-01
It is quite special and difficult to find shortest path in traffic network with turn penalties and prohibitions at intersections, which is beyond the area of classical algorithms based on the premise that the SPP( shortest path problem) is without aftereffect when labeling at nodes with traditional method. After a simple analysis about such SPP and some existing methods,a label correcting algorithm is presented to seek the shortest path from source to all the other nodes. According to the algorithm, every arc of the network is assigned a distance label and a pre-arc label which are scanned and updated iteratively to approximate the optimal solution. For a given network, the optimal solution can be got after certain iterations and the time complexity of the algorithm is O(nm) for general road network. A numerical example is given to illustrate the application.%在考虑交叉口延误和转向限制的情况下,交通网络中的最短路问题较为特殊和复杂,传统的节点标号方式及相应的基于无后效性条件的算法不适用于这类问题.本文对该类问题的特点及已有典型方法进行了分析,提出了一个基于孤标号的标号修正算法.算法分别为每条弧设置一个距离标号和一个紧前弧标号,通过不断迭代、更新弧的标号来寻找最短路径.对给定网络经一定次数的迭代,可得到起点至其它所有节点的最短路径,在“一对多”形式的路径优化中效果较好,应用于一般道路网时计算时间复杂性为O(nm).最后给出了一个数值算例,说明算法的应用.
Chongqin city tourism route design existing problem and countermeasure probing%重庆都市旅游线路设计存在问题与对策探讨
Institute of Scientific and Technical Information of China (English)
赵纲
2011-01-01
Rich tourism resources of Chongqing city,the development of tourism for the city to provide a solid foundation.Number of tourist routes in Chongqing city,has developed rapidly,attracting a large number of foreign tourists come to travel.However,the design of tourist routes in the city,there are still many problems,such as： product design,unreasonable travel routes,update the slow,inadequate publicity and so on.Chongqing City Tour for the design of many issues arise with cold hot spots,local conditions,strengthen brand awareness and other measures.%重庆都市旅游资源种类齐全,非常丰富,为发展都市旅游提供了坚实的基础。目前,重庆市旅行社经营的都市旅游线路众多、发展迅速,吸引了大量中外游客前来旅游。但是在都市旅游线路的设计上,如：景点搭配不合理、宣传力度不够等还存在诸多问题。本文针对重庆都市旅游线路设计中出现的问题提出了＂冷热搭配,因地制宜,加强宣传＂等的措施,希望能为发展重庆都市旅游线路提供一些建议。
A Model and Algorithm to Solve Vehicle Routing Problem with Split Delivery%需求可分的车辆路径问题模型与算法
Institute of Scientific and Technical Information of China (English)
谢秉磊; 胡小明; 张一喆
2012-01-01
需求可分的车辆路径问题(SDVRP)无论是从运输距离还是派车数量上,都可进一步优化传统的车辆路径问题.为了降低SDVRP的求解难度,本文在分析最优解性质的基础上,加强模型的约束条件,将原模型转变为等价的改进SDVRP,并在使用蚂蚁算法求解改进SDVRP模型的过程中,采用开发新路径和2-opt相结合的方法,以避免出现迭代停滞的现象.实验表明,算法计算结果稳定,最差解与最好解的偏差仅为1.80％.%Vehicle routing model with split delivery( SDVRP) can optimize further traditional vehicle routing problem in both transportation distance and the number of dispatching vehicle. To reduce the difficulty with the solution to SDVRP, based on analyzing properties of the optimal solution, the original model is transformed to the e-quivalent modified SDVRP through enforcing constraints of the original model. In the process of solving the modified SDVRP model with ant colony algorithm, exploring new routes and 2-opt are combined to avoid premature convergence. The experiments demonstrate that the computing results are stable: The bias between the worst solution and the best solution is only 1.80%.
International Nuclear Information System (INIS)
Tokamak fusion reactors will have large plasma currents of approximately 10 MA with hundreds of megajoules stored in the magnetic fields. When a major plasma instability occurs, the disruption of the plasma current induces voltage in the adjacent conducting structures, giving rise to large transient currents. The induced voltages may be sufficiently high to cause arcing across sector gaps or from one protruding component to another. This report reviews a tokamak arcing scenario and provides guidelines for designing tokamaks to minimize the possibility of arc damage
Institute of Scientific and Technical Information of China (English)
郭海湘; 杨娟; 於世为; 廖貅武
2012-01-01
以运输费用最小为目标,在考虑客户服务优先级和车辆装载率等约束条件下,构建了单车场单车型联合运输车辆路径问题模型和单车场多车型单点配送多趟服务车辆路径问题模型,并用改进的扫描算法和改进的遗传算法进行求解,最后,将郑州煤电物资供销有限公司的物资配送作为案例进行研究,从运输费用、运输里程和服务优先级三方面评价改进的扫描算法和改进的遗传算法的求解结果,得到在车辆装载率相同的情况下,两者各有所侧重:改进的遗传算法所求得的最优解在运输费用和配送里程上都优于改进的扫描算法,而改进的扫描算法则最大程度地保证了客户的服务优先级.%To minimize the delivering cost, we build a single-depot combined delivering vehicle routing problem model and a single-depot point-to-point delivering vehicle routing problem model, considering the constraints on the customers' service priorities and the full load rate of vehicles. We then present an improved sweeping algorithm and improved genetic algorithm to solve the mathematical models. We also study vehicle routing problem for Zhengzhou Coal Electricity Material Supply and Marketing Limited Company, evaluate the solutions in terms of delivery cost, delivery distance and full load rate of vehicles. The results show that, in the situation with the same full load rate of the vehicles, the best solution of the improved genetic algorithm is better than that of the improved sweeping algorithm in terms of delivery cost and delivery distance However, the improved sweeping algorithm provides guarantee for the service priority.
Adaptive routing in wireless communication networks using swarm intelligence
Arabshahi, P.; Gray, A.; Kassabalidis, I.; Das, A.; Narayanan, S.; Sharkawi, M. El; Marks, R. J.
2001-01-01
In this paper we focus on the network routing problem, and survey swarm intelligent approaches for its efficient solution, after a brief overview of power-aware routing schemes, which are important in the network examples outlined above.
Geographic Information System (GIS) modeling approach to determine the fastest delivery routes.
Abousaeidi, Mohammad; Fauzi, Rosmadi; Muhamad, Rusnah
2016-09-01
This study involves the adoption of the Geographic Information System (GIS) modeling approach to determine the quickest routes for fresh vegetable delivery. During transport, fresh vegetables mainly deteriorate on account of temperature and delivery time. Nonetheless, little attention has been directed to transportation issues in most areas within Kuala Lumpur. In addition, perishable food normally has a short shelf life, thus timely delivery significantly affects delivery costs. Therefore, selecting efficient routes would consequently reduce the total transportation costs. The regression model is applied in this study to determine the parameters that affect route selection with respect to the fastest delivery of fresh vegetables. For the purpose of this research, ArcGIS software with network analyst extension is adopted to solve the problem of complex networks. The final output of this research is a map of quickest routes with the best delivery times based on all variables. The variables tested from regression analysis are the most effective parameters to make the flow of road networks slower. The objective is to improve the delivery services by achieving the least drive time. The main findings of this research are that Land use such as residential area and population as variables are the effective parameters on drive time.
Geographic Information System (GIS) modeling approach to determine the fastest delivery routes.
Abousaeidi, Mohammad; Fauzi, Rosmadi; Muhamad, Rusnah
2016-09-01
This study involves the adoption of the Geographic Information System (GIS) modeling approach to determine the quickest routes for fresh vegetable delivery. During transport, fresh vegetables mainly deteriorate on account of temperature and delivery time. Nonetheless, little attention has been directed to transportation issues in most areas within Kuala Lumpur. In addition, perishable food normally has a short shelf life, thus timely delivery significantly affects delivery costs. Therefore, selecting efficient routes would consequently reduce the total transportation costs. The regression model is applied in this study to determine the parameters that affect route selection with respect to the fastest delivery of fresh vegetables. For the purpose of this research, ArcGIS software with network analyst extension is adopted to solve the problem of complex networks. The final output of this research is a map of quickest routes with the best delivery times based on all variables. The variables tested from regression analysis are the most effective parameters to make the flow of road networks slower. The objective is to improve the delivery services by achieving the least drive time. The main findings of this research are that Land use such as residential area and population as variables are the effective parameters on drive time. PMID:27579003
给定水平约束图的一类集成电路布线算法%An Algorithm for Routing Problem with Given Horizontal Constraint Graph
Institute of Scientific and Technical Information of China (English)
耿显亚; 房明磊; 刘斌; 张晓亮
2014-01-01
针对水平约束图为星图的具有曼哈顿模型的通道布线，提出了一个依据图论模型的最优轨道高度布线算法。该算法根据通道上结点的水平约束图和垂直约束图特点，依次安排好每一个结点的布线轨道，进而通过通孔可以把所有的结点在2层轨道上布线完成。通过计算分析，该算法能够达到最优的布线高度。%For a channel in 2-layer Manhattan model with horizontal constraint graph be star, we aim at interconnecting the terminals of each net by wires such that the circuit elements and the interconnecting wires are embedded into two planar layers by the methods of graph theory. Furthermore, the width (number of tracks required for routing) of a channel should be minimized. The constraints of a channel routing problem can be represented by a horizontal constraint graph (HCG) and a vertical constraint graph (VCG). Consider the two constraints, we improve the upper bound, we show that our algorithm can be obtain the best width.
INTERPOLATION WITH RESTRICTED ARC LENGTH
Institute of Scientific and Technical Information of China (English)
Petar Petrov
2003-01-01
For given data (ti,yi), I= 0,1,…,n,0 = t0 ＜t1 ＜…＜tn = 1we study constrained interpolation problem of Favard type inf{‖f"‖∞|f∈W2∞[0,1],f(ti)=yi,i=0,…,n,l(f;[0,1])≤l0}, wherel(f";[0,1])=∫1 0 / 1+f'2(x)dx is the arc length off in [0,1]. We prove the existence of a solution f* of the above problem, that is a quadratic spline with a second derivative f"* , which coincides with one of the constants - ‖f"*‖∞,0,‖f"*‖∞ between every two consecutive knots. Thus, we extend a result ofKarlin concerning Favard problem, to the case of restricted length interpolation.
Dynamic Routing with Security Considerations
Directory of Open Access Journals (Sweden)
G. Murali
2011-11-01
Full Text Available Now-a-days one of the major issues for data communication over wired and wireless networks is the security. the past work is on the designs of cryptography algorithms and system infrastructures. Apart from that we will propose a dynamic routing algorithm that could randomize delivery paths for data transmission. The algorithm is easy to implement and compatible with popular routing protocols, such as the Routing Information Protocol(RIP in wired networks and Destination-Sequenced Distance Vector(DSDV protocol in wireless networks, without introducing extra control messages. A clear study on the proposed algorithm is presented, and a series of simulation experiments are conducted to verify the results and to show the capability of the proposed algorithm. This algorithm is mainly proposed to improve the security and to overcome the limitations existing with the present cryptographic algorithms and protocols. Although some designs like IP security, Secure Socket Layer provide essential security, they unavoidably introduce substantial overheads in the Gateway/Host performance and effective network bandwidths. This routing protocol is compatible with the Routing Information Protocol which uses hop-count as its Routing metric. So there will be a limited number of hops and data transmissions are done by selecting hops randomly in a network. This improves security as well as controls traffic in the network. So, the procedure also includes using the multipath routing to select the paths to be followed. It uses the randomization process for selecting the number of hops to be selected for transforming the data. The routing table in this algorithm is based on the well-known Bellman-Ford algorithm. So, this overcomes the problems with security and traffic occurred with increase in the number of networks in these days
An Efficient Bypassing Void Routing Algorithm for Wireless Sensor Network
2015-01-01
Since the sensor node’s distribution in a wireless sensor network (WSN) is irregular, geographic routing protocols using the greedy algorithm can cause local minima problem. This problem may fail due to routing voids and lead to failure of data transmission. Based on the virtual coordinate mapping, this paper proposes an efficient bypassing void routing protocol to solve the control packet overhead and transmission delay in routing void of WSN, which is called EBVRPVCM. The basic idea is to t...
Routing in Optical and Stochastic Networks
Yang, S.
2015-01-01
In most types of networks (e.g., optical or transportation networks), finding one or more best paths from a source to a destination, is one of the biggest concerns of network users and providers. This process is known as routing. The routing problems differ accordingly depending on different applica
Optimizing departure times in vehicle routes
Kok, A.L.; Hans, E.W.; Schutten, J.M.J.
2008-01-01
Most solution methods for the vehicle routing problem with time windows (VRPTW) develop routes from the earliest feasible departure time. However, in practice, temporal traffic congestions make that such solutions are not optimal with respect to minimizing the total duty time. Furthermore, VRPTW sol
Anderlik, Csaba; Gregersen, Anders Rhod; Kleist, Josva; Peters, Andreas; Siaz, Pablo
2007-01-01
AliEn or Alice Environment is the Gridware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructur...
Institute of Scientific and Technical Information of China (English)
马祥丽; 张惠珍; 马良
2015-01-01
车辆路径问题(Vehicle Routing Problem,VRP)是组合优化问题中一个典型的NP难题.蝙蝠算法(Bat Algorithm,BA)是一种新型的智能优化算法,尚未被应用到求解VRP问题中去.根据物流配送中VRP问题的数学模型及其具体特征,设计了求解VRP问题的蝙蝠算法,并通过仿真实例和与其他算法进行比较的方式验证了蝙蝠算法求解VRP问题的有效性与可行性.
Institute of Scientific and Technical Information of China (English)
武秀焕; 李延晖
2009-01-01
考虑到随机需求库存路径问题(Inventory Routing Problem,IRP)本身所具有的马尔可夫、随机等特性,从其现实意义出发,将IRP描述为一个马尔可夫决策过程(Markov decision process,MDP).在运用非线性背包问题的求解方法得到初始策略并构成直接配送线路的基础上,提出一种本地搜索算法对其进行优化.通过实例演算.结果表明了该算法的实用性和有效性.
Institute of Scientific and Technical Information of China (English)
马祥丽; 张惠珍; 马良
2016-01-01
Vehicle Routing Problem with Time Windows(VRPTW)is an important and practical research project, which adds the time constraints into the mathematical model based on the capacity constraints with requirements of the lowest total cost in distribution system. Bat Algorithm(BA)is a new intelligent optimization algorithm, which has not yet been applied to VRPTW. Based on the mathematical model and specific features of VRPTW, this paper redesigns the operators of BA and proposes an improved bat algorithm for solving it. Furthermore, the results show that bat algorithm can effec-tively and feasibly solve VRPTW in logistics distribution through simulation examples and comparisons with other algo-rithms. The research results also expand the application field of BA.%带时间窗车辆路径问题(Vehicle Routing Problem with Time Windows,VRPTW)是一个重要而实际的研究课题,该问题在有能力约束模型的基础上增加了时间约束,要求配送系统总费用最低.蝙蝠算法(Bat Algorithm,BA)是一种新型的智能优化算法,目前尚未被应用到求解VRPTW问题中.根据VRPTW问题的数学模型及其具体特征,重新设计了BA的操作算子,给出了求解VRPTW问题的改进蝙蝠算法,并通过仿真实例和与其他算法进行比较的方式,验证了蝙蝠算法在VRPTW问题中的求解性能,拓展了蝙蝠算法的应用领域.
考虑时间窗与随机航行时间的船舶航线规划%Shipping routing problem with time windows and stochastic travel times
Institute of Scientific and Technical Information of China (English)
戴韬; 杨稀麟
2012-01-01
A good shipping routing planning is a key element for the shipping company to reduce its operation cost and improve its service quality. Considering there are two difficulties that uncertain travel time and scarcity of the resource in the docks, the shipping routing problem is abstracted to be a multiple Traveling Salesman Problem (TSP) with stochastic travel time and time window (m-TSPST) model. For the uncertain travel time, a linear approximate solution is designed, and the two-stage integer programing model and heuristic algorithm are built. At last, a numerical case is given to test the effectiveness of the model and algorithm.%良好的航线设计是船运公司降低运营成本,提高服务质量的关键.船舶运输中存在航行时间不确定,码头资源稀缺等特点,基于此将其航线问题抽象为考虑时间窗与随机旅行时间的多重流动旅行商问题.针对航行时间的随机性,设计了线性近似方法,提出了虚拟时间窗的概念,构建了初始模型与修正模型；给出了该问题的一个算例,验证了模型与算法的有效性和合理性.
同时送取货车辆路径问题算法研究综述%Algorithm review of vehicle routing problem with simultaneous delivery and pickup
Institute of Scientific and Technical Information of China (English)
王科峰; 叶春明; 李永林
2013-01-01
针对同时送取货车辆路径问题的研究算法进行了评述.将该问题的求解方法分为精确算法、构造型启发式、现代启发式以及并行算法四个大类.从算法的原理、性能、适用环境,以及算法之间差异性等方面对各类算法进行了较为全面的介绍.最后,说明了VRPSDP算法研究在节点具有双重需求车辆路径问题理论研究方面的意义,并提出未来VRPSDP算法研究的两个发展方向,即适合多处理器上运行的并行现代启发式算法,以及有效的混合算法如量子行为粒子群算法.%This paper gave a review about the algorithms for the vehicle routing problem with simultaneous delivery and pickup (VRPSDP). It divided the solving methods into four main classes; exact algorithm, constructive heuristics algorithm, meta-heuristics algorithm, and parallel algorithm. It also gave the detail introductions of the algorithms from the principle, performance, application environment, and the differences between them. In the end, it introduced the significance of the algorithm research of VRPSDP in the theory development of the vehicle routing problem with node having double demands. After that, it proposed two research directions in the future, which were parallel metaheuristics based on multiple processors, and the effec-tive hybrid algorithm such as quantum-behaved particle swarm optimization.
Institute of Scientific and Technical Information of China (English)
彭碧涛; 周世平
2016-01-01
同时取货和送货的三维装载约束下车辆路径问题（3L-VRPSDP）是经典车辆路径问题（VRP）的一个扩展，在3L-VRPSDP中，顾客可能要求同时取货和送货，而且货物装载要考虑其三维大小、先进后出、底面支撑等装载特性。针对这类问题，提出了基于左底优先和最大接触面优先的装载算法，在装载时要考虑其配送特征；在此基础上，设计了对应的禁忌搜索算法对初始结果进行优化，通过实验验证了算法的有效性。%The Simultaneous Delivery and Pickup Vehicle Routing Problem with Three-Dimension Loading Constraints (3L-VRPSDP)is a variant of the classical Vehicle Routing Problem(VRP)where clients may require simultaneous pickups and deliveries, at the same time, cargo must consider its three dimensional size, first in last out, bottom support constraints. Considering the distribution characteristics, the loading algorithms based on Left Bottom(LB)and Maximum Contact Area (MCA)are proposed, and the corresponding tabu search algorithms are designed. Experiments are given to prove the validity of the algorithms.
Routing Proposals for Multipath Interdomain Routing
Bilal, Sardar M.; Dilber, Muhammad Naveed; Khan, Atta ur Rehman
2013-01-01
Internet is composed of numbers of independent autonomous systems. BGP is used to disseminate reachability information and establishing path between autonomous systems. Each autonomous system is allowed to select a single route to a destination and then export the selected route to its neighbors. The selection of single best route imposes restrictions on the use of alternative paths during interdomain link failure and thus, incurred packet loss. Packet loss still occurs even when multiple pat...
Ant Colony Based Approach for Solving FPGA routing
Directory of Open Access Journals (Sweden)
Vinay Chopra
2011-07-01
Full Text Available This paper is based on an ant colony optimization algorithm (ASDR for solving FPGA routing for a route based routing constraint model in FPGA design architecture. In this approach FPGA routing task is transformed into a Boolean Satisfiabilty (SAT equation with the property that any assignment of input variables that satisfies the equation specifies a valid route. The Satisfiability equation is then modeled as Constraint Satisfaction problem, which helps in reducing procedural programming. Satisfying assignment for particular route will result in a valid routing and absence of a satisfying assignment implies that the layout is unroutable. In second step ant colony optimization algorithm is applied on the Boolean equation for solving routing alternatives utilizing approach of hard combinatorial optimization problems. The experimental results suggest that the developed ant colony optimization algorithm based router has taken extremely short CPU time as compared to classical Satisfiabilty based detailed router (SDR and finds all possible routes even for large FPGA circuits.
考虑装卸频率的大规模车辆路径问题研究%Research on large scale vehicle routing problem with handling frequency
Institute of Scientific and Technical Information of China (English)
马汉武; 徐森; 朱维
2011-01-01
Trough analyzing the characteristics of the large scale vehicle routing problem (LSVRP) and the solving difficulties, introduced the concept of handling frequency. Based on the conception, considered LSVRP in a new version, and established a multiple objectives planning model with the handling frequency. Proposed an improved hybrid genetic algorithm to solve the problem efficiently. Finally, introduced the improved hybrid genetic algorithm to solve the problem efficiently. The test proves that the algorithm, with practical value and broad application prospect, may greatly reduce the distribution cost and the handling frequency.%通过分析大规模车辆路径问题的特点和求解难点,从我国的配送实践出发,引入装卸频率的概念,从新的视角认识大规模车辆路径问题,建立了考虑装卸频率的车辆路径优化多目标规划模型,并设计了改进的混合遗传算法进行求解.实验结果表明,该算法能够大幅降低企业配送成本和配送的装卸频率,具有实际参考价值和应用前景.
Stochastic vehicle routing with recourse
DEFF Research Database (Denmark)
Gørtz, Inge Li; Nagarajan, Viswanath; Saket, Rishi
2012-01-01
instantiations, a recourse route is computed - but costs here become more expensive by a factor λ. We present an O(log2n ·log(nλ))-approximation algorithm for this stochastic routing problem, under arbitrary distributions. The main idea in this result is relating StochVRP to a special case of submodular...... orienteering, called knapsack rank-function orienteering. We also give a better approximation ratio for knapsack rank-function orienteering than what follows from prior work. Finally, we provide a Unique Games Conjecture based ω(1) hardness of approximation for StochVRP, even on star-like metrics on which our...
Routing in opportunistic networks
Dhurandher, Sanjay; Anpalagan, Alagan; Vasilakos, Athanasios
2013-01-01
This book provides a comprehensive guide to selected topics, both ongoing and emerging, in routing in OppNets. The book is edited by worldwide technical leaders, prolific researchers and outstanding academics, Dr. Isaac Woungang and co-editors, Dr. Sanjay Kumar Dhurandher, Prof. Alagan Anpalagan and Prof. Athanasios Vasilakos. Consisting of contributions from well known and high profile researchers and scientists in their respective specialties, the main topics that are covered in this book include mobility and routing, social-aware routing, context-based routing, energy-aware routing, incentive-aware routing, stochastic routing, modeling of intermittent connectivity, in both infrastructure and infrastructure-less OppNets. Key Features: Discusses existing and emerging techniques for routing in infrastructure and infrastructure-less OppNets. Provides a unified covering of otherwise disperse selected topics on routing in infrastructure and infrastructure-less OppNets. Includes a set of PowerPoint slides and g...
Small Universal Petri Nets with Inhibitor Arcs
Ivanov, Sergiu; Pelz, Elisabeth; Verlan, Sergey
2013-01-01
We investigate the problem of construction of small-size universal Petri nets with inhibitor arcs. We consider four descriptional complexity parameters: the number of places, transitions, inhibitor arcs, and the maximal degree of a transition, each of which we try to minimize. We give six constructions having the following values of parameters (listed in the above order): $(30,34,13,3)$, $(14, 31, 51, 8)$, $(11, 31, 79, 11)$, $(21,25,13,5)$, $(67, 64, 8, 3)$, $(58, 55, 8, 5)$ that improve the...
Modeling of Arc Force in Plasma Arc Welding
Institute of Scientific and Technical Information of China (English)
GAO Zhonglin; HU Shengsun; YIN Fengliang; WANG Rui
2008-01-01
A three. dimensional mathematical model for the transferred-type argon arc was developed to describe arc force on the anode surface. The software ANSYS was employed to solve the model. The model includes a part of torch and tungsten electrode to achieve m ore reasonable results. The arc temperature and flow fields were derived. And the influences of welding parameters on arc force were also studied. The simulated results show that arc pressure at the anode are dependent on the welding current, plasma gas flow rate and electrode neck-in, while not sensitive to arc length.
Vehicle routing problem in distribution with two-dimensional loading constraint%带二维装箱约束的物流配送车辆路径问题
Institute of Scientific and Technical Information of China (English)
王征; 胡祥培; 王旭坪
2011-01-01
In real distributions, there is a great amount of transportation problems called vehicle routing problem with two-dimensional loading constraint, in which items demanded by customers are usually fragile and needed to be packed into vehicles. This is a new problem that combines the two classical problems of vehicle routing problem and bin packing problem. To solve the problem, a mathematical model and a Memetic algorithm were presented after an explicit problem definition. The key modules of the algorithm, such as a depth-first based heuristic loading method, an encoding and splitting method of chromosomes, an initial solution generation method, crossover and local search methods, were explained in details. Based on some preliminary experiments, the best combination of parameters' values in Memetic algorithm was given. Finally, the robustness and the effectiveness of the Memetic algorithm were tested on Iori's 30 instances whose numbers of customers are from 20 to 199 and a comparison with other algorithm in the literature was made, which shows that the memetic algorithm greatly surpasses the algorithm on aspects of solving capacity and solution quality.%现实物流活动中大量存在的易损、易碎物品的运输问题属于带二维装箱约束的物流配送问题,该问题是二维装箱问题与车辆路径问题这两个经典难题融合之后的一个新问题.针对这一问题,在对其进行明确定义的基础上,建立了数学模型,提出了解决该问题一个Memetic算法,对算法中的几个关键算子:深度优先的启发式装箱方法、染色体的编码方式及其路径分割程序、初始解的生成方法、交叉算子、局部搜索算子,进行了详细的阐述.通过初步的实验,确定了Memetic算法的最佳参数配置；然后在Iori提出的30个顾客数在20 199个标准算例上对算法的鲁棒性、求解的质量、以及求解性能等几项指标进行了测试,并与文献中的求解结果进行了比
International Nuclear Information System (INIS)
AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a module implementing the functionalities necessary to achieve AliEn job submission and management to ARC enabled sites
MODELING PARAMETERS OF ARC OF ELECTRIC ARC FURNACE
Directory of Open Access Journals (Sweden)
R.N. Khrestin
2015-08-01
Full Text Available Purpose. The aim is to build a mathematical model of the electric arc of arc furnace (EAF. The model should clearly show the relationship between the main parameters of the arc. These parameters determine the properties of the arc and the possibility of optimization of melting mode. Methodology. We have built a fairly simple model of the arc, which satisfies the above requirements. The model is designed for the analysis of electromagnetic processes arc of varying length. We have compared the results obtained when testing the model with the results obtained on actual furnaces. Results. During melting in real chipboard under the influence of changes in temperature changes its properties arc plasma. The proposed model takes into account these changes. Adjusting the length of the arc is the main way to regulate the mode of smelting chipboard. The arc length is controlled by the movement of the drive electrode. The model reflects the dynamic changes in the parameters of the arc when changing her length. We got the dynamic current-voltage characteristics (CVC of the arc for the different stages of melting. We got the arc voltage waveform and identified criteria by which possible identified stage of smelting. Originality. In contrast to the previously known models, this model clearly shows the relationship between the main parameters of the arc EAF: arc voltage Ud, amperage arc id and length arc d. Comparison of the simulation results and experimental data obtained from real particleboard showed the adequacy of the constructed model. It was found that character of change of magnitude Md, helps determine the stage of melting. Practical value. It turned out that the model can be used to simulate smelting in EAF any capacity. Thus, when designing the system of control mechanism for moving the electrode, the model takes into account changes in the parameters of the arc and it can significantly reduce electrode material consumption and energy consumption
Institute of Scientific and Technical Information of China (English)
陈妍; 单汨源; 王秋凤
2015-01-01
Considering that heterogeneous fixed fleet vehicle routing problem with pickups and deliveries (HFFVRPPD) in logistics distribution is a widespread NP problem, which is more complex than single/multi vehicle with one way routing problem, HFFVRPPD optimization model was established to improve the load rate of vehicle, and reduce travel times. The algorithm of producing initial feasible solutions of the model was constructed, the improved simulated annealing algorithm was designed, which includes the operation of multi operators neighborhood based on the probability, embedding of memory devices, and the termination of many standard ways. The multi vehicle routing with one way problem and HFFVRPPD were compared to verify the effectiveness of the model and algorithm. The results show that the improved simulated annealing algorithm solving the HFFVRPPD is more convenient, and the HFFVRPPD optimization can effectively reduce the distribution costs.%针对客户存在收货和发货双重需求的物流配送问题，讨论具有多种车型的集配货一体化车辆路径问题。在综合考虑各车型的固定成本和可变配送成本的前提下，以总成本最小为目标，以尽可能提高车辆满载率、减少出行次数为思路，构建多车型集配货一体化车辆路径优化模型。基于最小插入费用法设计初始可行解生成算法，通过引入基于概率的多算子邻域操作、最优解记忆装置、多准则终止原则对模拟退火算法进行改进，给出求解思路。设计算例并对多车型单/双向集配货模型的求解结果进行比较，以验证模型的实用性和算法的有效性。研究结果表明：使用改进后的模拟退火算法对构建的多车型集配货一体化车辆路径问题模型求解更直接简便，对多车型集配货一体化车辆路径优化后能有效降低配送成本。
Trelles, J P; Vardelle, A; Heberlein, J V R
2013-01-01
Arc plasma torches are the primary components of various industrial thermal plasma processes involving plasma spraying, metal cutting and welding, thermal plasma CVD, metal melting and remelting, waste treatment and gas production. They are relatively simple devices whose operation implies intricate thermal, chemical, electrical, and fluid dynamics phenomena. Modeling may be used as a means to better understand the physical processes involved in their operation. This paper presents an overview of the main aspects involved in the modeling of DC arc plasma torches: the mathematical models including thermodynamic and chemical non-equilibrium models, turbulent and radiative transport, thermodynamic and transport property calculation, boundary conditions and arc reattachment models. It focuses on the conventional plasma torches used for plasma spraying that include a hot-cathode and a nozzle anode.
Pseudo-Cycle-Based Multicast Routing in Wormhole-Routed Networks
Institute of Scientific and Technical Information of China (English)
SONG JianPing (宋建平); HOU ZiFeng (侯紫峰); XU Ming (许铭)
2003-01-01
This paper addresses the problem of fault-tolerant multicast routing in wormholerouted multicomputers. A new pseudo-cycle-based routing method is presented for constructing deadlock-free multicast routing algorithms. With at most two virtual channels this technique can be applied to any connected networks with arbitrary topologies. Simulation results show that this technique results in negligible performance degradation even in the presence of a large number of faulty nodes.
Directory of Open Access Journals (Sweden)
Mohammad Arif
2012-05-01
Full Text Available Mobile ad hoc network (MANET is a collection of wireless mobile nodes. It dynamically forms atemporary network without using any pre existing network infrastructure or centralized administrationi.e. with minimal prior planning. All nodes have routing capabilities and forward data packets to othernodes in multi-hop fashion. As the network is dynamic, the network topology continuously experiencesalterations during deployment. The biggest challenge in MANETs is to find a path betweencommunicating nodes. The considerations of the MANET environment and the nature of the mobile nodescreate further complications which results in the need to develop special routing algorithms to meet thesechallenges. Swarm intelligence, a bio-inspired technique, which has proven to be very adaptable in otherproblem domains, has been applied to the MANET routing problem as it forms a good fit to the problem.In ant societies the activities of the individuals are not regulated by any explicit form of centralizedcontrol but are the result of self-organizing dynamics driven by local interactions and communicationsamong a number of relatively simple individuals. This unique characteristic has made ant societies anattractive and inspiring model for building new algorithms and new multi-agent systems. In this paper,we have studied and reviewed Ant Colony based routing algorithms and its variants. Finally, aperformance evaluation of the original ARA and the EARA is carried out with respect to each other.
Institute of Scientific and Technical Information of China (English)
Wenjun Xiao
2002-01-01
Wu, Lakshmivarahan and Dhall[5] recently described a deterministic, distributed routing scheme for some special classes of metacyclic graphs. However they have no proof of correctness that the scheme is a shortest path routing algorithm. In the note we give a suboptimal, deterministic routing algorithm.
Institute of Scientific and Technical Information of China (English)
彭勇; 殷树才
2014-01-01
车辆路径问题由于其广泛的应用领域及经济价值而成为学术研究热点。然而，在已有的研究文献中，车辆的速度时变与服务多任务特性很少被关注。本文讨论了具有这两个特性的单车路径优化问题。建立了以送货完成时间最早为优化目标的时变单车送货路径优化模型。由于很难获得该模型的精确解，本文提出了一种贪婪补货策略压缩原问题解空间，设计动态规划算法给出了车辆行驶时间满足FIFO规则的送货顺序近似最优解。数值算例验证了该算法所得到的解仅是原问题的近似最优解这一结论。算例同时表明优化配送时间随着车辆装载能力的增大而缩短，并在车辆装载能力超过所有客户配送总需求时实现最短配送时间，即，使用较大装载能力车辆能节约更多配送时间。%Vehicle routing problems have been extensively studied due to its extensive application and great value on economy.However, two constraints receive less attention , i.e., vehicle speed will be changed with time , and vehicle can service more than one trip .This paper discusses single vehicle routing problem with these two constraints .A mathematic model the optimal object of which is to find the route schedule which has the earliest task completion time is established .It's hard to achieve exact solutions of the problem .So the paper proposes a greed dispatching strategy for the model to compress solution space , and provides a dynamic programming algo-rithm with FIFO rule .The numerical examples demonstrate that for our model , the solution provided by dynamic programming algorithm is only a satisfactory solution .The numerical examples also indicate the optimal dispatc-hing time decreases while the vehicle load capacity increases , and it gets the minimum when the vehicle load ca-pacity is larger than customers total demand .That is, using larger capacity vehicle will save more dispatching
Institute of Scientific and Technical Information of China (English)
侯倩倩; 闫军; 廖理; 王博
2014-01-01
在协同物流的大趋势下，协同运输已成为了一种非常重要的运输方式。协同运输主要包括联盟内个体的自身资源整合以及联盟内各个企业的协同合作。在多个企业进行合作时，为了节约成本，可以有选择地将顾客委托给外部车场进行服务，这就是外部承运人可供选择下的车辆路径问题。目前，该问题的研究比较少。本文对外部承运人可供选择的车辆路径问题进行了分析研究，建立了该问题的数学模型并利用粒子群算法进行了求解。%Under the trend of collaborative logistics,collaborative transport has become an important mode of transportation .The collaborative transportation mainly includes the individual's own resources integration and the collaboration among enterprises within the alliance .In the process of collaboration among the alliance ,each customer is served by one of the vehicles of an internal fleet or by an external common carrier,in order to minimize the cost,which is called the Vehicle Routing Problem with Private Fleet and Common Carrier.At present,there is little study about this problem.In this paper,the problem is analyzed and solved by the particle swarm optimization ( PSO) while the mathematical mode is established land the corresponding process is shown.
Institute of Scientific and Technical Information of China (English)
代颖; 马祖军; 朱道立; 方涛
2012-01-01
进行震后应急物资配送系统优化是提高其配送绩效的重要手段.从系统集成优化的角度,研究应急物资配送中心定位与配送车辆路径安排的联合决策问题.综合考虑应急物资需求的模糊性、动态性和限制期,震后受损路网的动态恢复状况,不同类型有容量限制的配送车辆,以及物资需求分割配送等特点,以各物资需求点的应急物资运达时间之和最小为目标,采用机会约束规划方法建立了一个模糊动态定位—路径问题优化模型,并设计了一种两阶段启发式算法予以求解.最后,通过算例验证了该模型和算法的可行性及有效性.%Optimizing the delivery system for post-earthquake relief materials is an important way to enhance its operational performance. From the view point of integrated optimization, the joint decision problem of locating distribution centers and scheduling routes of delivery vehicles was studied. A chance-constrained programming model for the fuzzy dynamic location-routing problem was developed by considering the following characteristics : fuzzy and dynamic demand of relief materials, time window constraints, dynamic rehabilitation of affected road networks, heterogeneous capacitated delivery vehicles, and split deliveries. The goal is to minimize the total time in delivering relief materials to all affected areas. A two-phase heuristic algorithm was proposed to solve the model. Finally, the feasibility and validity of the model and algorithm was demonstrated by a numerical example.
Hafiz Abd Malek, Muhamad; Hayati Saad, Nor; Kiyai Abas, Sunhaji; Mohd Shah, Noriyati
2013-06-01
Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.
Anderlik, C; Kleist, J; Peters, A; Saiz, P
2008-01-01
AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a modu...
Link Perdurability Based Routing for Mobile Ad Hoc Networks
Institute of Scientific and Technical Information of China (English)
Sun Xuebin; Zhou Zheng
2003-01-01
Ad Hoc networks are prone to link failures due to mobility. In this letter, a link perdurability based routing scheme is proposed to try dealing with this problem. This scheme uses signal strength measurements to estimate the route life time and hence chooses a stable route, and is implemented in two typical ad hoc routing protocols to evaluate its performance. The simulation results have shown that this scheme can improve these protocols' packet delivery ratio in cases where there are frequent link failures.
State alternative route designations
Energy Technology Data Exchange (ETDEWEB)
1989-07-01
Pursuant to the Hazardous Materials Transportation Act (HMTA), the Department of Transportation (DOT) has promulgated a comprehensive set of regulations regarding the highway transportation of high-level radioactive materials. These regulations, under HM-164 and HM-164A, establish interstate highways as the preferred routes for the transportation of radioactive materials within and through the states. The regulations also provide a methodology by which a state may select alternative routes. First,the state must establish a ``state routing agency,`` defined as an entity authorized to use the state legal process to impose routing requirements on carriers of radioactive material (49 CFR 171.8). Once identified, the state routing agency must select routes in accordance with Large Quantity Shipments of Radioactive Materials or an equivalent routing analysis. Adjoining states and localities should be consulted on the impact of proposed alternative routes as a prerequisite of final route selection. Lastly, the states must provide written notice of DOT of any alternative route designation before the routes are deemed effective.
State alternative route designations
Energy Technology Data Exchange (ETDEWEB)
1989-07-01
Pursuant to the Hazardous Materials Transportation Act (HMTA), the Department of Transportation (DOT) has promulgated a comprehensive set of regulations regarding the highway transportation of high-level radioactive materials. These regulations, under HM-164 and HM-164A, establish interstate highways as the preferred routes for the transportation of radioactive materials within and through the states. The regulations also provide a methodology by which a state may select alternative routes. First,the state must establish a state routing agency,'' defined as an entity authorized to use the state legal process to impose routing requirements on carriers of radioactive material (49 CFR 171.8). Once identified, the state routing agency must select routes in accordance with Large Quantity Shipments of Radioactive Materials or an equivalent routing analysis. Adjoining states and localities should be consulted on the impact of proposed alternative routes as a prerequisite of final route selection. Lastly, the states must provide written notice of DOT of any alternative route designation before the routes are deemed effective.
Simulated Annealing Technique for Routing in a Rectangular Mesh Network
Directory of Open Access Journals (Sweden)
Noraziah Adzhar
2014-01-01
Full Text Available In the process of automatic design for printed circuit boards (PCBs, the phase following cell placement is routing. On the other hand, routing process is a notoriously difficult problem, and even the simplest routing problem which consists of a set of two-pin nets is known to be NP-complete. In this research, our routing region is first tessellated into a uniform Nx×Ny array of square cells. The ultimate goal for a routing problem is to achieve complete automatic routing with minimal need for any manual intervention. Therefore, shortest path for all connections needs to be established. While classical Dijkstra’s algorithm guarantees to find shortest path for a single net, each routed net will form obstacles for later paths. This will add complexities to route later nets and make its routing longer than the optimal path or sometimes impossible to complete. Today’s sequential routing often applies heuristic method to further refine the solution. Through this process, all nets will be rerouted in different order to improve the quality of routing. Because of this, we are motivated to apply simulated annealing, one of the metaheuristic methods to our routing model to produce better candidates of sequence.
带工作时间与时间窗的开放式车辆路径问题%Open Vehicle Routing Problem with Working Time and Time Windows
Institute of Scientific and Technical Information of China (English)
潘立军; 符卓; 刘喜梅
2012-01-01
在BtoC电子商务物流配送活动中,配送公司外包车辆和配送人员上班具有时间限制.为求解带工作时间与时间窗约束的开放式车辆路径问题(OVRPTWWT),构建其混合整数规划模型,给出一种求解该问题的非代际克隆选择算法,对算法中抗体的更新与抑制策略进行改进,设计出新的克隆选择方法.通过实验验证了该模型与OVRPTWWT非代际克隆选择算法的有效性.%In BtoC e-commerce logistics distribution activities, many distribution companies using outsourcing vehicles and the drivers have working time limit. On the basis of this, this paper proposes an Open Vehicle Routing Problem with Time Windows and Working Time (OVRPTWWT), and constructs its mixed integer planning model. A clonal selection algorithm for OVRPTWWT is proposed, it improves the antibodies updating procedure, restraining tactics and designs a new clonal selection method for the algorithm. An example verifies the efficiency of the model and algorithm.
Bee colony optimization algorithm for split delivery vehicle routing problem%需求可拆分车辆路径问题的蜂群优化算法
Institute of Scientific and Technical Information of China (English)
汪婷婷; 倪郁东; 何文玲
2014-01-01
In this paper ,the split delivery vehicle routing problem is researched and the mathematical optimization model w hich seeks the shortest distance to meet the delivery requirements is constructed . T he model releases the constraint that only one vehicle can be used to meet the delivery requirement for one customer .A new bee colony optimization(BCO) algorithm is proposed based on the improve-ment of the reaction threshold and the value of stimulatory signal .The experimental result proves the feasibility of the algorithm ,and also highlights the strong optimization ability of BCO algorithm by comparison with other typical algorithms .%文章研究了需求可拆分的车辆路径问题，通过解除传统车辆路径问题中每个任务点需求只能由1辆车满足的约束，建立了寻求满足配送要求最短行驶距离的数学优化模型，在改进反应阈值和刺激信号值的基础上提出了一种新型蜂群优化算法。仿真实验结果验证了算法的可行性，并通过与其他典型算法对比凸显了该算法较强的寻优能力。
Institute of Scientific and Technical Information of China (English)
黄秋爱; 李珍萍
2014-01-01
The vehicle routing problem with simultaneous delivery and pickup is studied in this paper. According to the practical case, the constraint of order limit is added. Then the mathematical model aiming at finding out the minimum distance is established. At the same time, an improved genetic algorithm based on the best selection method is designed and used to solve this model. Finally, the validity of the model and algorithm are tested by practical example.%研究了装卸一体化的车辆路径问题，根据问题的实际情况，增加了带有次序限制条件，并以总行驶路线最短为目标，建立了数学模型，并根据模型的特点，用改进的遗传算法进行求解。最后，通过具体实例验证了模型及算法的有效性。
Institute of Scientific and Technical Information of China (English)
田宇; 伍炜勤
2015-01-01
针对实际运输中顾客对不同车型、同时集送货物的多样化需求,文章建立了异车型同时集送车辆路径模型(vehicle routing problem with heterogeneous fleet,simultaneous pickup and delivery,VRPHSPD),并构建了基于多属性标签的蚁群系统算法(multi-label based ant colony system,MLACS)进行求解.该算法利用面向对象理念,分别对客户、车辆及其行驶路径构建多属性标签,首先用近邻法生成初始路径,再通过蚁群算法的搜索规则对客户和车辆标签进行匹配,从而得优化的结果.通过公开算例、实际应用案例的验证表明,MLACS算法能成功求解VRPHSPD问题,具有较高的求解质量、运算效率以及实际应用意义.
Integrated Models and Approach for Location Inventory and Routing Problem%选址-库存-路径问题模型及其集成优化算法
Institute of Scientific and Technical Information of China (English)
杜丽敬; 李延晖
2014-01-01
设施选址、库存控制和车辆路径安排是物流系统优化中的三个关键问题，三者之间存在相互依赖的关系，应该根据这种关系来相应地进行综合优化与管理物流活动。以典型的单一生产基地、单一产品、采用不断审查的（ Q， r）库存策略的供应链二级分销网络为研究对象，建立了一个随机型选址-库存-路径问题优化模型；在将非线性混合整数规划转化为线性整数集合覆盖模型的基础上，采用列生成算法来获得一个近似最优解，再用分支定价法对初始解进行改进，以实现对整个问题“完全集成”的优化。最后，用随机生成的方式，产生了10至160个客户的计算实例，分析了运输费用和库存费用对总成本的影响，算法运算时间表明本文给出的算法能较快地求解这一复杂问题。%Facility location , inventory control and vehicle routes scheduling are critical and highly related prob-lems in logistics system .The decision makers need to optimize the three problems integrated and comprehensive-ly.We formulate a stochastic Location-Inventory-Routing Problem(LIRP) model using continuous review (Q, r) inventory policy in two level supply chain distribution systems , consisting of one supplier , a set of retailers and a single type of product .Restructuring the non-linear mixed integer programming LIRP model into a set covering model, an approximate optimum solution is obtained using column generation .To realize the “integrated optimi-zation”, Brand-and-Price algorithm is applied to improve the initial solution .At last , based on the several in-stances generated randomly with sizes ranging from 10 to 160 retailers, the proposed approach is tested and eval-uated.The computational results show the proposed approach can resolve this complex problem efficiently .
Institute of Scientific and Technical Information of China (English)
秦家娇; 张勇; 毛剑琳; 付丽霞
2012-01-01
带时间窗车辆调度问题属于离散NP-hard组合优化问题,传统的粒子群算法在离散域上表现了一定的劣性,对此提出了一种基于粒子碰撞的离散PSO算法来求解该问题.受物体相互碰撞之后物体的速度和位置会发生改变的现象启发,使当前粒子与个体最优和全局最优粒子发生碰撞来更新粒子的位置,以避免传统更新操作中的取整,保证种群的进化能力.采用Solomon's VRP标准问题集的实例来对算法进行测试,实验结果数据表明了该算法的有效性.%The vehicle routing problem with time windows (VRPTW) is the NP-hard combinatorial optimization discrete problem. There was certain inferiority performance on solving it with traditional PSO, so this paper proposed a particles collision discrete PSO to solve it. Inspired by the physical phenomena of the velocity and position changed after objects collision, it made the current particle collided with the personal best particle and global best particle to avoid the tradition rounding operating in updating, and kept particles swarm evolutional capability. It used the Solomon' s VRP instance to test. The results of experiments show that the algorithm has good performance.
Institute of Scientific and Technical Information of China (English)
王君
2014-01-01
The Vehicle Routing Problem with Fuzzy Time Windows is addressed. A multi-objective mathematical model is designed with the objectives of logistics cost and average customer satisfaction. Based on Pareto dominance theory, a multi-objective tabu search algorithm is proposed to solve multi-objective optimization problems. Moreover, a dynamic program-ming method is embedded in the algorithm to optimize the customer satisfaction, which simplifies the original problem into tight path optimization sub-problems with the use of phasing. While fuzzy time windows are in piecewise linear and nonlinear convex membership function forms, customer beginning service time is optimized by proposed limited iteration subgradient algorithm and median iteration subgradient algorithm, respectively. Computational experiments on Solomon’s benchmark not only verify that the dynamic programming is more effective than projected subgradient methods to optimize the service level, but also show the advantages of the proposed multi-objective tabu search approach when compared with the well-known NSGA-II method.%为优化具有模糊时间窗的车辆路径问题，以物流配送成本和顾客平均满意度为目标，建立了多目标数学规划模型。基于Pareto占优的理论给出了求解多目标优化问题的并行多目标禁忌搜索算法，算法中嵌入同时优化顾客满意度的动态规划方法，运用阶段划分，把原问题分解为关于紧路径的优化子问题。对模糊时间窗为线性分段函数形式和非线性凹函数形式的隶属度函数，分别提出了次梯度有限迭代算法和次梯度中值迭代算法来优化顾客的最优开始服务时间。通过Solomon的标准算例，与次梯度投影算法的比较验证了动态规划方法优化服务水平的有效性，与主流的NSGA-II算法的对比实验表明了该研究提出的多目标禁忌搜索算法的优越性。
Performance Analysis of Route Discovery by Cross Layer Routing Protocol- RDCLRP
Directory of Open Access Journals (Sweden)
Mehajabeen Fatima
2013-06-01
Full Text Available Wired and wireless network is based on the TCP / IP architecture but it is not sufficient to cope with the dynamics of the MANET. Cross layer design can be an alternative architecture for MANET. Frequent route break is one of the major problems of mobile adhoc network (MANET. Path breaks due to less available battery power and mobility of nodes. Most of the battery power is consumed in flooding of control packets. A key challenge in the design of efficient routing protocol is to reduce link breakage and flooding of control packets. Route breakage can be reduced if the possibility of route breakage is predicted and a handoff is done without drop of data packets. If route breakage is reduced, the more battery power will be available with nodes. In turn it reduces the possibility of route breakage and the possibility of flooding. This is a cumulative effect. So a novel preemptive route repair algorithm is proposed named as RDCLRP- Route discovery by cross layer routing protocol to reduce frequency of control packet flooding and route breakage. Three variants of RDCLRP and their results are illustrated. In this paper, the impact of the number of nodes on performance of RDCLRP are investigated and analyzed. The results show 55.6% reduction in link breakage, 14.7% improvement in residual battery power and an average of 6.7% increase in throughput compared to basic AODV.
Semicircular Rashba arc spin polarizer
Energy Technology Data Exchange (ETDEWEB)
Bin Siu, Zhuo, E-mail: a0018876@nus.edu.sg [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Advanced Concepts and Nanotechnology, Data Storage Institute, DSI Building, 5 Engineering Drive 1 (Off Kent Ridge Crescent, NUS), Singapore 117608 (Singapore); Jalil, Mansoor B. A. [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Ghee Tan, Seng [Advanced Concepts and Nanotechnology, Data Storage Institute, DSI Building, 5 Engineering Drive 1 (Off Kent Ridge Crescent, NUS), Singapore 117608 (Singapore)
2014-05-07
In this work, we study the generation of spin polarized currents using curved arcs of finite widths, in which the Rashba spin orbit interaction (RSOI) is present. Compared to the 1-dimensional RSOI arcs with zero widths studied previously, the finite width presents charge carriers with another degree of freedom along the transverse width of the arc, in addition to the longitudinal degree of freedom along the circumference of the arc. The asymmetry in the transverse direction due to the difference in the inner and outer radii of the arc breaks the antisymmetry of the longitudinal spin z current in a straight RSOI segment. This property can be exploited to generate spin z polarized current output from the RSOI arc by a spin unpolarized current input. The sign of the spin current can be manipulated by varying the arc dimensions.
Network Resilience through Multiple Routing Configurations
Directory of Open Access Journals (Sweden)
Naga Raju Pamidi
2011-11-01
Full Text Available We propose the use of multi-topology (MT routing for network resilience against link and node failures. We describe the multi-topologies by an n-dimensional vector of different link costs for all links in the network. It is the base for the calculation of n shortest path trees from any node to all other destinations, i.e. for n virtual routing topologies. We define the link costs in such a way that the routing topologies complement each other in the sense that at least one valid route remains in a single link or node failure scenario for each pair of nodes in at least one routing topology. In such a failure case, packets are rather deviated over the intact routing topology than discarded. The recovery speed of the presented mechanism is very fast and can be compared to fast rerouting mechanisms in MPLS, which reduce packet, drops to a minimum. In contrast to MPLS, MT routing is still a pure IP-based solution that retains the scalability and the robustness of IP routing. As the Internet takes an increasingly central role in our communications infrastructure, the slow convergence of routing protocols after a network failure becomes a growing problem. To assure fast recovery from link and node failures in IP networks, we present a new recovery scheme called Multiple Routing Configurations (MRC. Our proposed scheme guarantees recovery in all single failure scenarios, using a single mechanism to handle both link and node failures, and without knowing the root cause of the failure. MRC is strictly connectionless, and assumes only destination based hop-by-hop forwarding. MRC is based on keeping additional routing information in the routers, and allows packet forwarding to continue on an alternative output link immediately after the detection of a failure. It can be implemented with only minor changes to existing solutions.
Dynamic Route Shortening and Route Repairing Mechanism for Mobile Ad Hoc Networks
Directory of Open Access Journals (Sweden)
T. R. Rangaswamy
2012-01-01
Full Text Available Problem statement: Ad hoc Networks are wireless networks without any fixed infrastructure. The network topology changes frequently and unpredictably due to the random movement of the nodes. The ad hoc on Demand Distant Vector Routing (AODV protocol works in a dynamic fashion, by establishing a route on demand and continues that route until it breaks. Due to the changing network topology of ad hoc networks, if other routes with less hop count become available, the network topology is not able to adapt until the route break occurs. Hence in the route shortening scheme is some redundant nodes in the active route is replaced with a node that is not on the active route. When there is any link failure between any two nodes, the alternative route with optimum route to be constructed and not sending RRER message to the source node to initiate the route discovery process again. Approach: This study proposes a new routing protocol called, Dynamic Route Shortening and Repairing mechanism (DRSR. The route shortening is incorporated with route repairing mechanism, to improve the performance of the AODV. The route shortening scheme works by replacing some redundant nodes in the active route, with a node that is not on the active route. If there is a link failure between the two nodes, the route repairing mechanism repairs the route, by using the nodes that are close enough to the route to overhear the message. Whenever the links go down, the DRSR replaces the failed links with the optimum route that is adjacent to the main route and not sending and RRER message to the source node to initiate the route discovery process again. The alternative route construction process could be initiated at any time, not just when a route has failed. The dynamically constructed alternative routeâs information is passed on to the upstream nodes, which then determine by themselves when to direct their packets to the Normal 0 false false false EN-US X
A Multistage Method for Multiobjective Route Selection
Wen, Feng; Gen, Mitsuo
The multiobjective route selection problem (m-RSP) is a key research topic in the car navigation system (CNS) for ITS (Intelligent Transportation System). In this paper, we propose an interactive multistage weight-based Dijkstra genetic algorithm (mwD-GA) to solve it. The purpose of the proposed approach is to create enough Pareto-optimal routes with good distribution for the car driver depending on his/her preference. At the same time, the routes can be recalculated according to the driver's preferences by the multistage framework proposed. In the solution approach proposed, the accurate route searching ability of the Dijkstra algorithm and the exploration ability of the Genetic algorithm (GA) are effectively combined together for solving the m-RSP problems. Solutions provided by the proposed approach are compared with the current research to show the effectiveness and practicability of the solution approach proposed.
DEFF Research Database (Denmark)
Anderlik, Csaba; Gregersen, Anders Rhod; Kleist, Josva;
2008-01-01
Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The interoperation has two aspects, one is the data......AliEn or Alice Environment is the Gridware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic...... management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. dCache provides support for several data management tools (among them for xrootd the tools used by AliEn) using the so called "doors". Therefore, we will concentrate on the second...
DEFF Research Database (Denmark)
Anderlik, Csaba; Gregersen, Anders Rhod; Kleist, Josva;
Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The interoperation has two aspects, one is the data......AliEn or Alice Environment is the Gridware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic...... management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. dCache provides support for several data management tools (among them for xrootd the tools used by AliEn) using the so called "doors". Therefore, we will concentrate on the second...
TBRF: Trust Based Routing Framework for WSNs
Directory of Open Access Journals (Sweden)
Kushal Gulaskar
2014-03-01
Full Text Available The multi-hop routing in wireless sensor networks (WSNs offers little protection against identity deception through replaying routing information. An adversary can exploit this defect to launch various harmful or even devastating attacks against the routing protocols, including sinkhole attacks, wormhole attacks and Sybil attacks. The situation is further aggravated by mobile and harsh network conditions. Traditional cryptographic techniques or efforts at developing trust-aware routing protocols do not effectively address this severe problem. To secure the WSNs against adversaries misdirecting the multi-hop routing, we have designed and implemented TBRF, a robust trust-aware routing framework for dynamic WSNs. Without tight time synchronization or known geographic information, TBRF provides trustworthy and energy-efficient route. Most importantly, TBRF proves effective against those harmful attacks developed out of identity deception; the resilience of TBRF is verified through extensive evaluation with both simulation and empirical experiments on large-scale WSNs under various scenarios including mobile and RF-shielding network conditions. Further, we have implemented a low-overhead TBRF module in TinyOS; as demonstrated, this implementation can be incorporated into existing routing protocols with the least effort. Based on TBRF, we also demonstrated a proof-of-concept mobile target detection application that functions well against an anti-detection mechanism
Architectural Surfaces and Structures from Circular Arcs
Shi, Ling
2013-12-01
In recent decades, the popularity of freeform shapes in contemporary architecture poses new challenges to digital design. One of them is the process of rationalization, i.e. to make freeform skins or structures affordable to manufacture, which draws the most attention from geometry researchers. In this thesis, we aim to realize this process with simple geometric primitives, circular arcs. We investigate architectural surfaces and structures consisting of circular arcs. Our focus is lying on how to employ them nicely and repetitively in architectural design, in order to decrease the cost in manufacturing. Firstly, we study Darboux cyclides, which are algebraic surfaces of order ≤ 4. We provide a computational tool to identify all families of circles on a given cyclide based on the spherical model of M ̈obius geometry. Practical ways to design cyclide patches that pass through certain inputs are presented. In particular, certain triples of circle families on Darboux cyclides may be suitably arranged as 3-webs. We provide a complete classification of all possible 3-webs of circles on Darboux cyclides. We then investigate the circular arc snakes, which are smooth sequences of circu- lar arcs. We evolve the snakes such that their curvature, as a function of arc length, remains unchanged. The evolution of snakes is utilized to approximate given surfaces by circular arcs or to generated freeform shapes, and it is realized by a 2-step pro- cess. More interestingly, certain 6-arc snake with boundary constraints can produce a smooth self motion, which can be employed to build flexible structures. Another challenging topic is approximating smooth freeform skins with simple panels. We contribute to this problem area by approximating a negatively-curved 5 surface with a smooth union of rational bilinear patches. We provide a proof for vertex consistency of hyperbolic nets using the CAGD approach of the rational B ́ezier form. Moreover, we use Darboux transformations for the
Brown, I.
2014-01-01
The vacuum arc ion source has evolved into a more or less standard laboratory tool for the production of high-current beams of metal ions, and is now used in a number of different embodiments at many laboratories around the world. Applications include primarily ion implantation for material surface modification research, and good performance has been obtained for the injection of high-current beams of heavy-metal ions, in particular uranium, into particle accelerators. As the use of the sourc...
Partially dynamic vehicle routing - models and algorithms
DEFF Research Database (Denmark)
Larsen, Allan; Madsen, Oli B.G.; Solomon, M.
2002-01-01
In this paper we propose a framework for dynamic routing systems based on their degree of dynamism. Next, we consider its impact on solution methodology and quality. Specifically, we introduce the Partially Dynamic Travelling Repairman Problem and describe several dynamic policies to minimize...... routing costs. The results of our computational study indicate that increasing the dynamic level results in a linear increase in route length for all policies studied. Furthermore, a Nearest Neighbour policy performed, on the average, uniformly better than the other dispatching rules studied. Among these...
Indian Academy of Sciences (India)
S Ghorul; S N Sahasrabudhe; P S S Murthy; A K Das; N Venkatramani
2002-07-01
Understanding of the basic nature of arc root ﬂuctuation is still one of the unsolved problems in thermal arc plasma physics. It has direct impact on myriads of thermal plasma applications being implemented at present. Recently, chaotic nature of arc root behavior has been reported through the analysis of voltages, acoustic and optical signals which are generated from a hollow copper electrode arc plasma torch. In this paper we present details of computations involved in the estimation process of various dynamic properties and show how they reﬂect chaotic behavior of arc root in the system.
Distributed Decision Making in Combined Vehicle Routing and Break Scheduling
Meyer, Christoph Manuel; Kopfer, Herbert; Kok, Adrianus Leendert; Schutten, Marco
2009-01-01
The problem of combined vehicle routing and break scheduling comprises three subproblems: clustering of customer requests, routing of vehicles, and break scheduling. In practice, these subproblems are usually solved in the interaction between planners and drivers. We consider the case that the planner performs the clustering and the drivers perform the routing and break scheduling. To analyze this problem, we embed it into the framework of distributed decision making proposed by Schneeweiss (...
Kammenhuber, Nils
2011-01-01
Despite the bursty and highly volatile traffic, routing in the Internet today is optimised only on coarse time scales, as load-adaptive routing is known to induce performance deterioration by causing massive oscillations. We describe ReplEx, an universally applicable distributed algorithm for dynamic routing/traffic engineering, which is based on game theory. We show through extensive realistic simulations that ReplEx does not oscillate, and that it achieves performance gains comparable to tr...
Underestimated risks of recurrent long-range ash dispersal from northern Pacific Arc volcanoes
Bourne, A. J.; Abbott, P. M.; Albert, P. G.; Cook, E.; Pearce, N. J. G.; Ponomareva, V.; Svensson, A.; Davies, S. M.
2016-07-01
Widespread ash dispersal poses a significant natural hazard to society, particularly in relation to disruption to aviation. Assessing the extent of the threat of far-travelled ash clouds on flight paths is substantially hindered by an incomplete volcanic history and an underestimation of the potential reach of distant eruptive centres. The risk of extensive ash clouds to aviation is thus poorly quantified. New evidence is presented of explosive Late Pleistocene eruptions in the Pacific Arc, currently undocumented in the proximal geological record, which dispersed ash up to 8000 km from source. Twelve microscopic ash deposits or cryptotephra, invisible to the naked eye, discovered within Greenland ice-cores, and ranging in age between 11.1 and 83.7 ka b2k, are compositionally matched to northern Pacific Arc sources including Japan, Kamchatka, Cascades and Alaska. Only two cryptotephra deposits are correlated to known high-magnitude eruptions (Towada-H, Japan, ca 15 ka BP and Mount St Helens Set M, ca 28 ka BP). For the remaining 10 deposits, there is no evidence of age- and compositionally-equivalent eruptive events in regional volcanic stratigraphies. This highlights the inherent problem of under-reporting eruptions and the dangers of underestimating the long-term risk of widespread ash dispersal for trans-Pacific and trans-Atlantic flight routes.
Underestimated risks of recurrent long-range ash dispersal from northern Pacific Arc volcanoes.
Bourne, A J; Abbott, P M; Albert, P G; Cook, E; Pearce, N J G; Ponomareva, V; Svensson, A; Davies, S M
2016-01-01
Widespread ash dispersal poses a significant natural hazard to society, particularly in relation to disruption to aviation. Assessing the extent of the threat of far-travelled ash clouds on flight paths is substantially hindered by an incomplete volcanic history and an underestimation of the potential reach of distant eruptive centres. The risk of extensive ash clouds to aviation is thus poorly quantified. New evidence is presented of explosive Late Pleistocene eruptions in the Pacific Arc, currently undocumented in the proximal geological record, which dispersed ash up to 8000 km from source. Twelve microscopic ash deposits or cryptotephra, invisible to the naked eye, discovered within Greenland ice-cores, and ranging in age between 11.1 and 83.7 ka b2k, are compositionally matched to northern Pacific Arc sources including Japan, Kamchatka, Cascades and Alaska. Only two cryptotephra deposits are correlated to known high-magnitude eruptions (Towada-H, Japan, ca 15 ka BP and Mount St Helens Set M, ca 28 ka BP). For the remaining 10 deposits, there is no evidence of age- and compositionally-equivalent eruptive events in regional volcanic stratigraphies. This highlights the inherent problem of under-reporting eruptions and the dangers of underestimating the long-term risk of widespread ash dispersal for trans-Pacific and trans-Atlantic flight routes. PMID:27445233
Underestimated risks of recurrent long-range ash dispersal from northern Pacific Arc volcanoes.
Bourne, A J; Abbott, P M; Albert, P G; Cook, E; Pearce, N J G; Ponomareva, V; Svensson, A; Davies, S M
2016-01-01
Widespread ash dispersal poses a significant natural hazard to society, particularly in relation to disruption to aviation. Assessing the extent of the threat of far-travelled ash clouds on flight paths is substantially hindered by an incomplete volcanic history and an underestimation of the potential reach of distant eruptive centres. The risk of extensive ash clouds to aviation is thus poorly quantified. New evidence is presented of explosive Late Pleistocene eruptions in the Pacific Arc, currently undocumented in the proximal geological record, which dispersed ash up to 8000 km from source. Twelve microscopic ash deposits or cryptotephra, invisible to the naked eye, discovered within Greenland ice-cores, and ranging in age between 11.1 and 83.7 ka b2k, are compositionally matched to northern Pacific Arc sources including Japan, Kamchatka, Cascades and Alaska. Only two cryptotephra deposits are correlated to known high-magnitude eruptions (Towada-H, Japan, ca 15 ka BP and Mount St Helens Set M, ca 28 ka BP). For the remaining 10 deposits, there is no evidence of age- and compositionally-equivalent eruptive events in regional volcanic stratigraphies. This highlights the inherent problem of under-reporting eruptions and the dangers of underestimating the long-term risk of widespread ash dispersal for trans-Pacific and trans-Atlantic flight routes.
Bo, Pengbo
2011-07-01
The most important guiding principle in computational methods for freeform architecture is the balance between cost efficiency on the one hand, and adherence to the design intent on the other. Key issues are the simplicity of supporting and connecting elements as well as repetition of costly parts. This paper proposes so-called circular arc structures as a means to faithfully realize freeform designs without giving up smooth appearance. In contrast to non-smooth meshes with straight edges where geometric complexity is concentrated in the nodes, we stay with smooth surfaces and rather distribute complexity in a uniform way by allowing edges in the shape of circular arcs. We are able to achieve the simplest possible shape of nodes without interfering with known panel optimization algorithms. We study remarkable special cases of circular arc structures which possess simple supporting elements or repetitive edges, we present the first global approximation method for principal patches, and we show an extension to volumetric structures for truly threedimensional designs. © 2011 ACM.
Finding routes in anonymous sensor networks
Dutra, Renato C.; Barbosa, Valmir C
2005-01-01
We consider networks of anonymous sensors and address the problem of constructing routes for the delivery of information from a group of sensors in response to a query by a sink. In order to circumvent the restrictions imposed by anonymity, we rely on using the power level perceived by the sensors in the query from the sink. We introduce a simple distributed algorithm to achieve the building of routes to the sink and evaluate its performance by means of simulations.
Efficient Networks Communication Routing Using Swarm Intelligence
Koushal Kumar
2012-01-01
As demonstrated by natural biological swarm’s collective intelligence has an abundance of desirable properties for problem-solving like in network routing. The focus of this paper is in the applications of swarm based intelligence in information routing for communication networks. As we know networks are growing and adopting new platforms as new technologies comes. Also according to new demands and requirements networks topologies and its complexity is increasing with time. Thus it is becomin...
Burleigh, Scott C.
2011-01-01
Contact Graph Routing (CGR) is a dynamic routing system that computes routes through a time-varying topology of scheduled communication contacts in a network based on the DTN (Delay-Tolerant Networking) architecture. It is designed to enable dynamic selection of data transmission routes in a space network based on DTN. This dynamic responsiveness in route computation should be significantly more effective and less expensive than static routing, increasing total data return while at the same time reducing mission operations cost and risk. The basic strategy of CGR is to take advantage of the fact that, since flight mission communication operations are planned in detail, the communication routes between any pair of bundle agents in a population of nodes that have all been informed of one another's plans can be inferred from those plans rather than discovered via dialogue (which is impractical over long one-way-light-time space links). Messages that convey this planning information are used to construct contact graphs (time-varying models of network connectivity) from which CGR automatically computes efficient routes for bundles. Automatic route selection increases the flexibility and resilience of the space network, simplifying cross-support and reducing mission management costs. Note that there are no routing tables in Contact Graph Routing. The best route for a bundle destined for a given node may routinely be different from the best route for a different bundle destined for the same node, depending on bundle priority, bundle expiration time, and changes in the current lengths of transmission queues for neighboring nodes; routes must be computed individually for each bundle, from the Bundle Protocol agent's current network connectivity model for the bundle s destination node (the contact graph). Clearly this places a premium on optimizing the implementation of the route computation algorithm. The scalability of CGR to very large networks remains a research topic
Using Ant Colony Optimization for Routing in VLSI Chips
Arora, Tamanna; Moses, Melanie
2009-04-01
Rapid advances in VLSI technology have increased the number of transistors that fit on a single chip to about two billion. A frequent problem in the design of such high performance and high density VLSI layouts is that of routing wires that connect such large numbers of components. Most wire-routing problems are computationally hard. The quality of any routing algorithm is judged by the extent to which it satisfies routing constraints and design objectives. Some of the broader design objectives include minimizing total routed wire length, and minimizing total capacitance induced in the chip, both of which serve to minimize power consumed by the chip. Ant Colony Optimization algorithms (ACO) provide a multi-agent framework for combinatorial optimization by combining memory, stochastic decision and strategies of collective and distributed learning by ant-like agents. This paper applies ACO to the NP-hard problem of finding optimal routes for interconnect routing on VLSI chips. The constraints on interconnect routing are used by ants as heuristics which guide their search process. We found that ACO algorithms were able to successfully incorporate multiple constraints and route interconnects on suite of benchmark chips. On an average, the algorithm routed with total wire length 5.5% less than other established routing algorithms.
ACO Agent Based Routing in AOMDV Environment
Directory of Open Access Journals (Sweden)
Kaur Amanpreet
2016-01-01
Full Text Available Mobile Ad-hoc Network (MANET is a group of moving nodes which can communicate with each other without the help of any central stationary node. All the nodes in the MANET act as router for forwarding data packets. The nodes in the network also move randomly and there exists no fixed infrastructure. So, path breaks are the frequent problem in MANET. The routing protocol faces a lot of problem due these path breaks. Therefore, the routing protocol which is multipath in nature is more reliable than a unipath routing protocol. Ant colony optimization is a relatively new technique which is suitable for the optimization problems. AOMDV is a multipath routing protocol. Thus, if there happens to be path break, the packets can start following the new path which has already been selected. In this paper, we are trying to add ant’s agents into AOMDV behavior. In this way, the new protocol will be benefited by the dual properties i.e. of ant’s nature and multipath nature of AOMDV. The modified concept is simulated and the outcomes are compared with AOMDV, AODV and DSR routing protocols for few performance parameters. Results obtained are encouraging; the new algorithm performs better than traditional unipath and multipath routing protocols.
Routing Trains Through Railway Junctions: A New Set Packing Approach
DEFF Research Database (Denmark)
Lusby, Richard; Larsen, Jesper; Ryan, David;
The problem of routing trains through railway junctions is an integral part of railway operations. Large junctions are highly interconnected networks of track where multiple railway lines meet, intersect, and split. The number of possible routings makes this a very complicated problem. Here we show...
Institute of Scientific and Technical Information of China (English)
寇明顺; 叶春明; 陈子皓
2012-01-01
为了提高粒子群算法求解车辆路径问题时收敛速度和全局搜索能力,将蜜蜂繁殖进化机制与粒子群算法相结合,应用到CVRP问题的求解.该算法中,最优的个体作为蜂王与通过选择机制选择的雄蜂以随机概率进行交叉,增强了最优个体信息的应用能力;同时,随机产生一部分雄蜂种群,并将其与蜂王交叉增加了算法的多样性.实例分析表明该算法具有较好的全局搜索能力,验证了该算法的可行性.%The vehicle routing problem (VRP) is discussed in this paper. There are studies that solve VRP by using particle swarm optimization (PSO) algorithm. However, with traditional PSO, it has slow convergence rate and a local optimum may be obtained. In order to improve the performance of PSO, an algorithm called bee evolutionary particle swarm optimization (BEPSO) is presented for VRP in this paper. By this algorithm, the best particle regarded as the queen crosses with the selected drones randomly. In this way, it takes the advantage of the best individual's information. At the same time, some drones are randomly generated and crossed with the queen such that diversity is enlarged. Experimental test shows that the proposed algorithm has better global search ability than the existing ones.
Institute of Scientific and Technical Information of China (English)
朱亚琪; 方建安
2012-01-01
针对物流车辆路径优化问题,考虑到基本蚁群算法有收敛速度慢、易陷入局部最优的缺点,采用了一种双种群蚁群算法,在蚁群的基础上引入差分进化(DE)和粒子群算法(PSO).通过在PSOAS种群和DEAS种群之间建立一种信息交流机制,使信息能够在两个种群中传递,以免某一方因错误的信息判断而陷入局部最优点.通过matlab仿真实验测试,表明该群智能混合算法可以较好地解决TSP的问题.%Aiming at the drawbacks of slow convergence speed and being easy to fall into local optimal point for basic ant colony algorithm in logistics vehicle routing optimization issue, this paper adoptes a Dual Population Ant Colony Algorithm, Differential Evolution (DE) and Particle Swarm Optimization (PSO) is introduced on the basis of the ant colony. Through the establishment of an information exchange mechanism between PSOAS population and DEAS population, so that information can be passed in the two populations, so as not to be trapped in local minima due to wrong judgment. Matlab simulation experiment showes that the group of intelligent hybrid algorithm can solve the TSP problem.
Institute of Scientific and Technical Information of China (English)
王超; 金淳; 韩庆平
2016-01-01
This paper proposed a multi-objective model for capacitated vehicle routing problem (CVRP)facing different target preference (MOCVRPFDTP)to solve CVRP more effectively and evaluate transportation cost comprehensively.There were three different preference structures in this model,which were joint optimization of loading and CVRP,absolute minimum vehi-cles preference,and path optimization preference.To solve this model,this paper constructed an algorithm framework with cor-responding algorithms.In experiments,the model and its solving methods display satisfactory performance in the testing for VR-PLIB,and they are more suitable for practical instance.%为了更有效地求解车辆路径问题、全方位地评估物流运输成本，提出了面向不同目标偏好的车载能力约束车辆路径问题的多目标优化模型（MOCVRPFDTP），其包括三种不同的偏好结构：装载与 CVRP 联合优化、绝对最小车辆数偏好及路径优化偏好。为了求解该模型，设计了算法架构及具体算法。在实验中，该模型及其求解方法对 CVRP 国际标准算例 VRPLIB 的测试结果显示了令人满意的性能，并且它更适用于实际 CVRP 问题的求解。
Institute of Scientific and Technical Information of China (English)
魏江宁; 陆志强; 奚立峰
2009-01-01
The vehicle routing problem with time windows as well as multiple pickups and deliveries was studied in collaborative transportation mode. A mathematical model was developed considering the factors such as the number of trucks rented, the distances covered, and the penalty due to service delay. A hybrid genetic algorithm was proposed accordingly, integrating the restarting scheme which is able to improve the initial population and avoid premature convergence respectively. In addition, the local research strategy was fully used to get the optimal value quickly. The results of the computational experiment indicate that the proposed algorithm is effective.%研究了协同物流模式下,单车库、多集散点的带时间窗以及单点多批次配送与集货请求的联合运输问题.考虑车辆的租用费用、行驶费用、未按时完成服务产生的惩罚费用等因素,建立了数学模型并提出了混合遗传算法.算法中加入了重启动机制,以提高种群质量和避免早熟收敛,并采用局部搜索策略以快速寻找最优值.数值实验证明,混合遗传算法求解该类运输调度问题具有良好的效果,且算法效率较高.
DEFF Research Database (Denmark)
Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications. The first part of the book reviews...... the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...
Hybrid heuristic algorithm for heterogeneous open vehicle routing problem%多车型开放式车辆路线问题的混合启发式算法
Institute of Scientific and Technical Information of China (English)
王晓博; 任春玉; 李海晨
2013-01-01
多车型开放式车辆路线问题，是物流配送优化中不可缺少的环节。针对标准遗传算法存在收敛速度慢，局部搜索能力差，易早熟的缺点，采用混合启发式算法进行优化求解。采用实数序列编码，使问题变得更简洁；有针对性地构建初始解，提高了解的可行性；用基于排序的选择与最佳保留相结合策略，保证群体的多样性；引入部分算术交叉算子，加强染色体的全局搜索能力；利用模拟退火算法的 Boltzmann 机制，控制遗传算法的交叉、变异操作，提高了算法的收敛速度和搜索效率。仿真结果表明混合启发式算法在求解质量和计算效率上好于标准遗传算法。%Heterogeneous open vehicle routing problem is logistics optimization indispensable part. According to the standard genetic algorithm shortcomings of slowly convergent speed, weakly partial searching ability and easily premature, hybrid heuristic algorithm is used to optimize the solution. The paper uses sequence of real numbers coding so as to simplify the problem, con-structs the targeted initial solution to improve the feasibility, adopts a choice based on sort of a combination with the best reten-tion strategies to ensure the diversity of population, and uses some arithmetic crossover operator to enhance whole search ability of the chromosome. Using Boltzmann simulated annealing mechanism for controlling genetic algorithm crossover and mutation operations, it improves the convergence speed and search efficiency. Finally, the good performance can be proved by experiment calculation and concrete examples.
Investigation of pellet acceleration by an arc heated gas gun
International Nuclear Information System (INIS)
This report describes work on pellet acceleration by means of an arc heated gas gun. The work is a continuation of the work described in RISO-M-2536. The aim of the work is to obtain velocities well above 2 km/s for 3.2 mm diameter deuterium pellets. By means of a cryogenic arc chamber in which the hydrogen propellant is pre-condensed, extruded deutetrium pellets are accelerated up to a maximum velocity of 1.93 km/s. When increasing the energy input to the arc in order to increase the pellet velocity further the heat input to the extrusion/punching pellet loading mechanism was found to be critical: preparation of pellets became difficult and cooling times between shots became inconveniently long. In order to circumvent this problems the concept of a room temperature hydrogen propellant pellet fed arc chamber was proposed. Preliminary results from acceleration of polyurethane pellets with this arc chamber are described as well as the work of developing of feed pellet guns for this chamber. Finally the report describes design consideration for a high pressure propellant pellet fed arc chamber together with preliminary results obtained with a proto-type arc chamber. (author)
Improving Reactive Ad Hoc Routing Performance by Geographic Route Length
Institute of Scientific and Technical Information of China (English)
CAO Yuan-da; YU Yan-bing; LU Di
2005-01-01
In order to help reactive ad hoc routing protocols select better-performance routes, a novel metric named geographic route length (GRL) is proposed. The relationship between GRL metric and routing performance is analyzed in detail. Combined with hop metric, GRL is applied into the original ad hoc on-demand distance vector (AODV) to demonstrate its effectiveness. Simulation experiments have shown that GRL can effectively reduce packet delay and route discovery frequency, thus can improve reactive ad hoc routing performance.
A New Route Maintenance in Dynamic Source Routing Protocol
Shukla, Ashish
2010-01-01
Mobile ad-hoc network (MANET) is infrastructureless, self-organizable, multi hop packet switched network. A number of routing protocols for MANETs have been proposed in recent years. Dynamic Source Routing (DSR) protocol is one of the most popular routing protocol for ad hoc networks. This paper presents a novel method to enhance route maintenance part of DSR protocol. Our proposed route maintenance significantly increases the efficiency of the protocol at the time of route failures.
Survivable Lightpath Routing in WDM Optical Networks
Institute of Scientific and Technical Information of China (English)
LIUFengqing; ZENGQingji; ZHUXu; YANGXudong; XIAOShilin
2004-01-01
In IP over WDM networks, when a failure(such as a fiber cut) occurs, the service restoration can be implemented by dynamic routing in IP layer. But it needs that the logical topology remains connected after any physical link failure. Otherwise, IP layer cannot find an alternate path to restore the service. The problem of routing logical links (lightpaths) on a physical network topology in a way that the logical topology remains connected in the event of single physical link failure is called survivabl erouting. In this paper~ we address the survivable routing problem by proposing a new ILP algorithm that works well with sparse-connected logical topologies. The necessary and sufficient conditions for survivable routing are simplified, which greatly reduces the number of survivable constraints. Based-on the simplified conditions, a new ILP formulation with K-shortest paths as alternate paths for a logical link is presented, which mainly reduces the number of ILP variables. Finally, numerical results are given and discussed to show that most survivable routing solutions can be found with our algorithms, and the time needed to find such a survivable routing solution is much smaller than other similar methods.
Manet Load Balancing Parallel Routing Protocol
Directory of Open Access Journals (Sweden)
Hesham Arafat Ali
2012-07-01
Full Text Available In recent years, multi-path routing protocols have attained more attention in mobile ad hoc networks as compared to other routing schemes due to their abilities and efficiency in improving bandwidth of communication, increasing delivery reliability, responding to congestion and heavy traffic. Several protocols have been developed to address multi path routing, but it always has a problem that the discovered paths may be not 100% disjoint and sending data is done in only one path until it's broken; the discovery of multiple paths also generates more overhead on the network. Load Balancing Parallel Routing Protocol [LBPRP] tried to solve previous multi path problems, distributing traffic among multiple paths sending data in parallel form as it uses all paths in the same time. We employed a simple test scenario to be sure of proposed model efficiency and to validate the proposed Load Balancing Parallel Routing Protocol. [LBPRP] will achieve load balancing in sending data, decreasing the end-to-end delay and increasing the packet delivery ratio and throughput, thus the performance of multi-path routing protocols can be improved consequently.
Passive Visual Sensing in Automatic Arc Welding
DEFF Research Database (Denmark)
Liu, Jinchao
the interference of the extremely strong arc light and controlling the exposure time of the camera on the y to capture dierent images for seam tracking and weld pool sensing. From the software side, we have designed a passive seam detection algorithm based on robust estimation techniques which can detect the seam......-circuit moment. The essence is that deformable models can be immune to spurious edges caused by strong arc light and/or re ection from the seam by incorporating prior information on regions and boundaries. The main ndings are organized and presented in this dissertation....... industrial solutions for seam detection such as using laser scanners suer from several limitations. For instance, it must be positioned some distance ahead to the molten pool and may cause problem when dealing with shiny surfaces. Existing techniques for weld pool sensing mostly rely on auxiliary light...
A multicast routing algorithm with multiple trees
Institute of Scientific and Technical Information of China (English)
Cui Xunxue; Gao Wei; Fang Hongyu
2005-01-01
Quality of service (QoS) multicast routing has continued to be a very important research topic in the Internet.A method of multicast routing is proposed to simultaneously optimize several parameters based on multiobjective genetic algorithm, after the related work is reviewed. The contribution lies on that the selection process of such routing is treated with multiobjective optimization. Different quality criterions in IP network are taken into account for multicast communications. A set of routing trees is generated to approximate the Pareto front of multicast problem. Multiple trees can be selected from the final set of nondominated solutions, and applied to obtain a good overall link cost and balance traffic distribution according to some simulation results.
ACRR: Ad Hoc On-Demand Distance Vector Routing with Controlled Route Requests
Kataria, Jayesh; Sanyal, Sugata
2010-01-01
Reactive routing protocols like Ad Hoc On-Demand Distance Vector Routing (AODV) and Dynamic Source Routing (DSR)in Ad-Hoc Wireless Networks which are used in Mobile and Ad Hoc Networks (MANETs) work by flooding the network with control packets. There is generally a limit on the number of these packets that can be generated or forwarded. But a malicious node can disregard this limit and flood the network with fake control packets. These packets hog the limited bandwidth and processing power of genuine nodes in the network while being forwarded. Due to this, genuine route requests suffer and many routes either do not get a chance to materialize or they end up being longer than otherwise. In this paper we propose a non cryptographic solution to the above problem and prove its efficiency by means of simulation.
Understanding individual routing behaviour.
Lima, Antonio; Stanojevic, Rade; Papagiannaki, Dina; Rodriguez, Pablo; González, Marta C
2016-03-01
Knowing how individuals move between places is fundamental to advance our understanding of human mobility (González et al. 2008 Nature 453, 779-782. (doi:10.1038/nature06958)), improve our urban infrastructure (Prato 2009 J. Choice Model. 2, 65-100. (doi:10.1016/S1755-5345(13)70005-8)) and drive the development of transportation systems. Current route-choice models that are used in transportation planning are based on the widely accepted assumption that people follow the minimum cost path (Wardrop 1952 Proc. Inst. Civ. Eng. 1, 325-362. (doi:10.1680/ipeds.1952.11362)), despite little empirical support. Fine-grained location traces collected by smart devices give us today an unprecedented opportunity to learn how citizens organize their travel plans into a set of routes, and how similar behaviour patterns emerge among distinct individual choices. Here we study 92 419 anonymized GPS trajectories describing the movement of personal cars over an 18-month period. We group user trips by origin-destination and we find that most drivers use a small number of routes for their routine journeys, and tend to have a preferred route for frequent trips. In contrast to the cost minimization assumption, we also find that a significant fraction of drivers' routes are not optimal. We present a spatial probability distribution that bounds the route selection space within an ellipse, having the origin and the destination as focal points, characterized by high eccentricity independent of the scale. While individual routing choices are not captured by path optimization, their spatial bounds are similar, even for trips performed by distinct individuals and at various scales. These basic discoveries can inform realistic route-choice models that are not based on optimization, having an impact on several applications, such as infrastructure planning, routing recommendation systems and new mobility solutions. PMID:26962031
Dahomey Breeding Bird Survey Route
US Fish and Wildlife Service, Department of the Interior — Document contains route directions and map for the naitonal Dahomey BBS route. Includes milage for where specific listening stations are located along the route...
Sleep-Route: Routing through Sleeping Sensors
Sarkar, Chayan; Rao, Vijay S.; Prasad, R. Venkatesha
2014-01-01
In this article, we propose an energy-efficient data gathering scheme for wireless sensor network called Sleep-Route, which splits the sensor nodes into two sets - active and dormant (low-power sleep). Only the active set of sensor nodes participate in data collection. The sensing values of the dormant sensor nodes are predicted with the help of an active sensor node. Virtual Sensing Framework (VSF) provides the mechanism to predict the sensing values by exploiting the data correlation among ...
C.M. Meyer; Kok, A.L.; H Kopfer; Schutten, J.M.J.
2009-01-01
We analyze the problem of combined vehicle routing and break scheduling from a distributed decision making perspective. The problem of combined vehicle routing and break scheduling can be defined as the problem of finding vehicle routes to serve a set of customers such that a cost criterion is minimized and legal rules on driving and working hours are observed. In the literature, this problem is always analyzed from a central planning perspective. In practice, however, this problem is solved ...
Our Brothers' Keepers: Secure Routing with High Performance
Brodsky, Alex
2008-01-01
The Trinity (Brodsky et al., 2007) spam classification system is based on a distributed hash table that is implemented using a structured peer-to-peer overlay. Such an overlay must be capable of processing hundreds of messages per second, and must be able to route messages to their destination even in the presence of failures and malicious peers that misroute packets or inject fraudulent routing information into the system. Typically there is tension between the requirements to route messages securely and efficiently in the overlay. We describe a secure and efficient routing extension that we developed within the I3 (Stoica et al. 2004) implementation of the Chord (Stoica et al. 2001) overlay. Secure routing is accomplished through several complementary approaches: First, peers in close proximity form overlapping groups that police themselves to identify and mitigate fraudulent routing information. Second, a form of random routing solves the problem of entire packet flows passing through a malicious peer. Thi...
Comprehensive restoration performance analyzed under different routing and rerouting policies
Lei, Bo; Lee, Peiyuan; Gu, Wanyi
2005-11-01
This paper studies the routing and wavelength assignment (RWA) problem in wavelength-routed all-optical networks with dynamic traffic demand. As well known, the performance of network restoration strongly depends upon the routing and rerouting policies. In this letter, we comprehensively analyzed the restoration performance under two main alternate dynamic routing algorithm, LLR(Least Loaded Routing) and FPLC(Fixed-Paths Least-Congestion routing), and two rerouting policies, based on K-path backup or Dijkstra algorithm. Through modelling and simulation, we compute the restoration efficiencies of four combinations on the NSFNET T1 backbone network, with different traffic load. The numerical simulation result shows that the rerouting policy based on Dijkstra algorithm has improved more 10%-20% performance than the rerouting policy based on K-path backup. The LLR and FPLC routing algorithm achieve the same performance by and large when the same rerouting policy is used.
Great Ellipse Route Planning Based on Space Vector
Directory of Open Access Journals (Sweden)
LIU Wenchao
2015-07-01
Full Text Available Aiming at the problem of navigation error caused by unified earth model in great circle route planning using sphere model and modern navigation equipment using ellipsoid mode, a method of great ellipse route planning based on space vector is studied. By using space vector algebra method, the vertex of great ellipse is solved directly, and description of great ellipse based on major-axis vector and minor-axis vector is presented. Then calculation formulas of great ellipse azimuth and distance are deduced using two basic vectors. Finally, algorithms of great ellipse route planning are studied, especially equal distance route planning algorithm based on Newton-Raphson(N-R method. Comparative examples show that the difference of route planning between great circle and great ellipse is significant, using algorithms of great ellipse route planning can eliminate the navigation error caused by the great circle route planning, and effectively improve the accuracy of navigation calculation.
Bhanot, Gyan; Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard D.; Takken, Todd E.; Vranas, Pavlos M.
2009-09-08
Class network routing is implemented in a network such as a computer network comprising a plurality of parallel compute processors at nodes thereof. Class network routing allows a compute processor to broadcast a message to a range (one or more) of other compute processors in the computer network, such as processors in a column or a row. Normally this type of operation requires a separate message to be sent to each processor. With class network routing pursuant to the invention, a single message is sufficient, which generally reduces the total number of messages in the network as well as the latency to do a broadcast. Class network routing is also applied to dense matrix inversion algorithms on distributed memory parallel supercomputers with hardware class function (multicast) capability. This is achieved by exploiting the fact that the communication patterns of dense matrix inversion can be served by hardware class functions, which results in faster execution times.
Institute of Scientific and Technical Information of China (English)
黄震; 罗中良; 黄时慰
2015-01-01
A hybrid ant colony algorithm was proposed.Because,ant colony algorithm used to solve the vehicle routing problem with time windows (VRPTW)is easy to fall into local optimum,and the quality of initial population in genetic algorithm affects the effectiveness of the algorithm directly.Firstly,the al-gorithm introduces the factors of time windows into node selection probability formula of ant colony algo-rithm to get the initial population.Secondly,the crossover and the mutation were operated to get a better path for the initial population.Applying Matlab environment for hybrid algorithm simulation,the effects on the vehicle utilization and path planning is obvious.It shows the algorithm is efficient,and can avoid falling into local optimum.%针对带时间窗车辆路径问题求解时蚁群算法存在容易陷入局部最优，而遗传算法初始种群的优劣对算法有效性存在直接影响，提出一种混合蚁群优化算法。算法首先在蚁群算法的节点选择概率公式中引入时间窗因素，以得到初始种群，然后通过遗传算法的交叉算子和变异算子对初始种群中的较优路径进行交叉和变异操作，从而得到更优的路径。通过 Matlab 环境下对文中混合算法进行仿真实验，在车辆利用率和路径规划上效果明显，表明了算法的高效性，同时混合算法可以避免陷入局部最优。
Locating Depots for Capacitated Vehicle Routing
Goertz, Inge Li
2011-01-01
We study a location-routing problem in the context of capacitated vehicle routing. The input is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so that all demands are satisfied and the total cost is minimized. Our main result is a constant-factor approximation algorithm for this problem. To achieve this result, we reduce to the k-median-forest problem, which generalizes both k-median and minimum spanning tree, and which might be of independent interest. We give a (3+c)-approximation algorithm for k-median-forest, which leads to a (12+c)-approximation algorithm for the above location-routing problem, for any constant c>0. The algorithm for k-median-forest is just t-swap local search, and we prove that it has locality gap 3+2/t; this generalizes the corresponding result known for k-median. Finally we consider the "non-uniform" k-median-forest problem which has different cost ...
Directory of Open Access Journals (Sweden)
David J. Aldous
2016-04-01
Full Text Available Modeling a road network as a planar graph seems very natural. However, in studying continuum limits of such networks it is useful to take {\\em routes} rather than {\\em edges} as primitives. This article is intended to introduce the relevant (discrete setting notion of {\\em routed network} to graph theorists. We give a naive classification of all 71 topologically different such networks on 4 leaves, and pose a variety of challenging research questions.
Scoped Bellman-Ford Geographic Routing for Large Dynamic Wireless Sensor Networks
Institute of Scientific and Technical Information of China (English)
Xue Zhang; Jue Hong; Sang-Lu Lu; Li Xie; Jian-Nong Cao
2008-01-01
Routing is a fundamental problem in wireless sensor networks. Most previous routing protocols are challenged when used in large dynamic networks as they suffer from either poor scalability or the void problem. In this paper, we propose a new geographic routing protocol, SBFR (Scoped Bellman-Ford Routing), for large dynamic wireless sensor networks. The basic idea is that each node keeps a view scope of the network by computing distance vectors using the distributed BellmanFord method, and maintains a cost for routing to the sink. When forwarding a packet, a node picks the node with minimum cost in its routing table as a temporary landmark. While achieving good scalability, it also solves the void problem in an efficient manner through the combination of Bellman-Ford routing and cost-based geographic routing. Analytical and simulation results show that SBFR outperforms other routing protocols not only because of its robustness and scaiability but also its practicality and simplicity.
LMOP Based Hybrid Routing Strategy for Delay/Disruption Tolerant Networks
Qian Liu; Chao Chen; Fuhong Lin; Haitao Xu; Kraser Michael
2014-01-01
In this paper, routing problem of Delay Tolerant Networks (DTN) was investigated and a new routing scheme was proposed based on the Epidemic routing. By combining the advantage of a variety of related routing algorithm, a Limited Multi-copy Optimal Path-Hybrid Routing (LMOP-HR） was put forward belonging to the flooding message copies strategy. An optimal tree mixed strategy based on priority was proposed for the message distribution. Further, this strategy adopted priority-based c...
Burns, Joseph A.; Thomas, P. C.; Helfenstein, P.; Tiscareno, M. S.; Hedman, M. M.; Agarwal, M.
2012-10-01
New scenarios for the origins of Saturn’s rings/interior moons have directed scientific attention to the region just exterior to Saturn’s main rings. Four satellites (Aegaeon = Ae; Anthe = An; Methone = Me; Pallene = Pa) discovered by the Cassini mission on either side of Mimas’s orbit perhaps comprise a distinct class of ring-moon. They are tiny (R = 0.3-2.5 km); three (AeAnMe) are trapped in co-rotation resonances with Mimas and reside within ring-arcs; and at least two (MePa) have remarkably regular shapes. Images with pixel scales as fine as 27 m taken in May 2012 reveal Methone to be ovoid within 10 m (from sub-pixel limb detection) and devoid of any craters (>130 m) across its 9 km2 of surface; Pallene and even tiny Aegaeon have similar appearances in lesser-quality images. Numerical simulations demonstrate that particles comprising the surrounding ring-arcs populate the same resonances as their embedded moons; escape speeds from the moons are bodies. In this environment, the moons’ shapes are smooth equipotentials; electrostatic effects may also determine how grains settle to surfaces. Considering these shapes to represent equipotential surfaces for rotating, tidally distorted, homogeneous bodies, we infer mean satellite densities of 250+/-60 (Pa), 310+/-30 (Me), and 540+/-120 (Ae) kg m-3. About half of Methone’s leading hemisphere is covered by a sharply bounded, lemon-shaped, relatively dark region, having a form reminiscent of Mimas’s thermal anomaly (Howett et al. 2011). Its (601 nm) albedo is 13% lower than the bounding brighter material. An irregularly shaped, even-darker (by 4%) blotch straddles the apex of the moon’s motion. Impacts with circum-planetary meteoroids and plasma are likely responsible for these features.
Crosstalk-Aware Routing Resource Assignment
Institute of Scientific and Technical Information of China (English)
Hai-Long Yao; Yi-Ci Cai; Qiang Zhou; Xian-Long Hong
2005-01-01
Crosstalk noise is one of the emerging issues in deep sub-micrometer technology which causes many undesired effects on the circuit performance. In this paper, a Crosstalk-Aware Routing Resource Assignment (CARRA) algorithm is proposed, which integrates the routing layers and tracks to address the crosstalk noise issue during the track/layer assignment stage. The CARRA problem is formulated as a weighted bipartite matching problem and solved using the linear assignment algorithm. The crosstalk risks between nets are represented by an undirected graph and the maximum number of the concurrent crosstalk risking nets is computed as the max clique of the graph. Then the nets in each max clique are assigned to disadjacent tracks. Thus the crosstalk noise can be avoided based on the clique concept. The algorithm is tested on IBM benchmarks and the experimental results show that it can improve the final routing layout a lot with little loss of the completion rate.
Evaluation of Flood Routing Techniques for Incremental Damage Assessment
Jayyousi, Enan Fakhri
1994-01-01
Incremental damage assessment is a tool used to assess the justification for expensive modifications of inadequate dams. The input data to incremental damage assessment are the output from the breach analysis and flood routing. For this reason, flood routing should be conducted carefully. Distorted results from the flood routing technique or unstable modeling of the problem will distort the results of an incremental damage assessment, because an error in the estimated incremental stage will c...
Energy Aware Simple Ant Routing Algorithm for Wireless Sensor Networks
2015-01-01
Network lifetime is one of the most prominent barriers in deploying wireless sensor networks for large-scale applications because these networks employ sensors with nonrenewable scarce energy resources. Sensor nodes dissipate most of their energy in complex routing mechanisms. To cope with limited energy problem, we present EASARA, an energy aware simple ant routing algorithm based on ant colony optimization. Unlike most algorithms, EASARA strives to avoid low energy routes and optimizes the ...
BALANCE ROUTING TRAFFIC IN GENERALIZED SHUFFLE-EXCHANGE NETWORK
Institute of Scientific and Technical Information of China (English)
Chen Zhen; Liu Zengji; Qiu Zhiliang; Chen Peng; Tao Xiaoming
2005-01-01
A methodology is proposed to handle problem that under equiproble address of packet traffic at the input port, Generalized Shuffle-Exchange Network (GSEN) routes traffic unevenly because of the unbalanced routing tags. The idea is to use routing tag according to probability, which can be evaluated by using Moore-Penrose inverse in matrix analysis. An instance is used to illustrate the idea, and the simulation is done to show the improvement in performance issues.
Geocasting and Multicasting Routing Operation in Mobile Ad Hoc Network
R.Kruthika
2013-01-01
The paper considers, the different multicasting routing protocols in wireless mobile Ad hoc network (MANET).An Ad hoc network is composed of mobile nodes without the presence of a wired support infrastructure .In this environment routing/multicasting protocols are faced with the challenge of producing multihop router under host mobility and band constraints. Various approaches and routing protocol have been proposed to address Ad hoc networking problems and multiple standardization effort wit...
Routing Service Quality—Local Driver Behavior Versus Routing Services
DEFF Research Database (Denmark)
Ceikute, Vaida; Jensen, Christian S.
2013-01-01
of the quality of one kind of location-based service, namely routing services. Specifically, the paper presents a framework that enables the comparison of the routes provided by routing services with the actual driving behaviors of local drivers. Comparisons include route length, travel time, and also route...... experiments with real vehicle trajectory data and an existing online navigation service. It is found that the availability of information about previous trips enables better prediction of route travel time and makes it possible to provide the users with more popular routes than does a conventional navigation...
Directory of Open Access Journals (Sweden)
Drexl, Michael
2011-01-01
Full Text Available The generalized truck-and-trailer routing problem (GTTRP constitutes a unified model for vehicle routing problems with trailers and a fixed lorry-trailer assignment. The GTTRP is a generalization of the truck-and-trailer routing problem (TTRP, which itself is an extension of the well-known vehicle routing problem (VRP. In the GTTRP, the vehicle fleet consists of single lorries and lorry-trailer combinations. Some customers may be visited only by a single lorry or by a lorry without its trailer, some may also be visited by a lorry-trailer combination. In addition to the customer locations, there is another relevant type of location, called transshipment location, where trailers can be parked and where a load transfer from a lorry to its trailer can be performed. In this paper, two mixed-integer programming (MIP formulations for the GTTRP are presented. Moreover, an exact solution procedure for the problem, a branch-and-price algorithm, and heuristic variants of this algorithm are described. Computational experiments with the algorithms are presented and discussed. The experiments are performed on randomly generated instances structured to resemble real-world situations and on TTRP benchmark instances from the literature. The results of the experiments show that instances of realistic structure and size can be solved in short time and with high solution quality by a heuristic algorithm based on column generation. || El problema generalizado de rutas de trenes de carretera (generalized truck-and-trailer routing problem, GTTRP constituye un modelo unificado para problemas de rutas de vehículos con remolques y asignación fija camión-remolque. El GTTRP es una generalización del truck-and-trailer routing problem (TTRP, que es una extensión del conocido problema de rutas de vehículos (vehicle routing problem, VRP. En el GTTRP, la flota de vehículos consiste en camiones sin remolque (camiones solos y trenes de carretera. Algunos clientes pueden
Modeling Routing Overhead Generated by Wireless Reactive Routing Protocols
Javaid, Nadeem; Javaid, Akmal; Malik, Shahzad A
2011-01-01
In this paper, we have modeled the routing over- head generated by three reactive routing protocols; Ad-hoc On-demand Distance Vector (AODV), Dynamic Source Routing (DSR) and DYnamic MANET On-deman (DYMO). Routing performed by reactive protocols consists of two phases; route discovery and route maintenance. Total cost paid by a protocol for efficient routing is sum of the cost paid in the form of energy consumed and time spent. These protocols majorly focus on the optimization performed by expanding ring search algorithm to control the flooding generated by the mechanism of blind flooding. So, we have modeled the energy consumed and time spent per packet both for route discovery and route maintenance. The proposed framework is evaluated in NS-2 to compare performance of the chosen routing protocols.
Directory of Open Access Journals (Sweden)
Liu Yu-Jen
2016-01-01
Full Text Available Electric arc is a discharge phenomenon caused by particular electrical events and arc produced facilities in power system, for example the occurrence of short-circuit fault in feeders and the use of electric arc furnace for steel-making. All of these electric arcs have a highly nonlinear nature and can be considered as a significant source of power quality problems. To investigate the impacts of the electric arcs on power quality studies the development of the electric arc models for simulation analysis is became necessary. This paper thus presents the use of different one-dimensional interpolation methods for modelling the alternating current electric arc. The performances of different methods are compared by simulation results that are derived from the modelling of an alternating current electric arc furnace load and a low-frequency fluorescent tube.
Multirate Anypath Routing in Wireless Mesh Networks
Laufer, Rafael
2008-01-01
In this paper, we present a new routing paradigm that generalizes opportunistic routing in wireless mesh networks. In multirate anypath routing, each node uses both a set of next hops and a selected transmission rate to reach a destination. Using this rate, a packet is broadcast to the nodes in the set and one of them forwards the packet on to the destination. To date, there is no theory capable of jointly optimizing both the set of next hops and the transmission rate used by each node. We bridge this gap by introducing a polynomial-time algorithm to this problem and provide the proof of its optimality. The proposed algorithm runs in the same running time as regular shortest-path algorithms and is therefore suitable for deployment in link-state routing protocols. We conducted experiments in a 802.11b testbed network, and our results show that multirate anypath routing performs on average 80% and up to 6.4 times better than anypath routing with a fixed rate of 11 Mbps. If the rate is fixed at 1 Mbps instead, p...
The Route Analysis Based On Flight Plan
Feriyanto, Nur; Saleh, Chairul; Fauzi, Achmad; Rachman Dzakiyullah, Nur; Riza Iwaputra, Kahfi
2016-02-01
Economic development effects use of air transportation since the business process in every aspect was increased. Many people these days was prefer using airplane because it can save time and money. This situation also effects flight routes, many airlines offer new routes to deal with competition. Managing flight routes is one of the problems that must be faced in order to find the efficient and effective routes. This paper investigates the best routes based on flight performance by determining the amount of block fuel for the Jakarta-Denpasar flight route. Moreover, in this work compares a two kinds of aircraft and tracks by calculating flight distance, flight time and block fuel. The result shows Jakarta-Denpasar in the Track II has effective and efficient block fuel that can be performed by Airbus 320-200 aircraft. This study can contribute to practice in making an effective decision, especially helping executive management of company due to selecting appropriate aircraft and the track in the flight plan based on the block fuel consumption for business operation.
Arc Interference Behavior during Twin Wire Gas Metal Arc Welding Process
Directory of Open Access Journals (Sweden)
Dingjian Ye
2013-01-01
Full Text Available In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc is added to the middle arc (M-arc in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.
Phone Routing using the Dynamic Memory Model
DEFF Research Database (Denmark)
Bendtsen, Claus Nicolaj; Krink, Thiemo
2002-01-01
In earlier studies a genetic algorithm (GA) extended with the dynamic memory model has shown remarkable performance on real-world-like problems. In this paper we experiment with routing in communication networks and show that the dynamic memory GA performs remarkable well compared to ant colony...
Optimal partial-arcs in VMAT treatment planning
Wala, Jeremiah; Chen, Wei; Craft, David
2012-01-01
Purpose: To improve the delivery efficiency of VMAT by extending the recently published VMAT treatment planning algorithm vmerge to automatically generate optimal partial-arc plans. Methods and materials: A high-quality initial plan is created by solving a convex multicriteria optimization problem using 180 equi-spaced beams. This initial plan is used to form a set of dose constraints, and a set of partial-arc plans is created by searching the space of all possible partial-arc plans that satisfy these constraints. For each partial-arc, an iterative fluence map merging and sequencing algorithm (vmerge) is used to improve the delivery efficiency. Merging continues as long as the dose quality is maintained above a user-defined threshold. The final plan is selected as the partial arc with the lowest treatment time. The complete algorithm is called pmerge. Results: Partial-arc plans are created using pmerge for a lung, liver and prostate case, with final treatment times of 127, 245 and 147 seconds. Treatment times...
Study on the problems to BX1-200-3 arc welding transformers%BX1-200-3型弧焊变压器使用中存在的问题
Institute of Scientific and Technical Information of China (English)
李明利; 胡静
2011-01-01
根据某职业学校使用BX1-200-3型孤焊变压器对学生进行焊接实际操作培训时焊机接连出现损坏的现象,对该弧焊变压器的电气组成和原理进行了分析说明,指出了该弧焊变压器在电路结构和控制方法上存在的隐患及造成焊机损坏的原因,即两公共电源接线端子所接电源种类必须与焊机转换开关的档位保持严格对应关系,否则实际操作时稍有差错,即会造成风扇电机因过压而击穿或因欠压而烧毁,进而短时间内引起弧焊变压器线圈冒烟起火,焊机彻底损坏.对焊机生产厂家改进该种弧焊电源电气结构和控制方法具有一定的参考作用,对至今仍在使用该种型号弧焊变压器的用户具有一定的参考价值.%According to the phenomenon of continuous damage of BX1-200-3-type arc welding transformers when students of a vocational school in Beijing taking hands-on training courses,the paper describes the electrical component and the principles of the welding transformer, pointing out that there are risks about the arc transformer in the circuit structure and control methods.That is, the switch behind the welding transformers should maintain strict correspondence with the power type of the two public power terminals connected,otherwise once a slight mistake occurs in the actual operation,it will be very likely to lead to the situation that the fan motor breakdowns due to high voltage or burns due to low voltage, the are welding transformer coil smokes and gets fired after a short time,and at last the welding machine is damaged completely. The paper can be used as a reference by the welding machine manufacturers to improve the electric structure and the control method of welding machine of this type,and can still be used as a reminder and emphasis for users who are now using this type of arc welding transformer.
Integrated cargo routing and ship scheduling in liner shipping
DEFF Research Database (Denmark)
Kjeldsen, Karina Hjortshøj
The problem consists of creating routes and schedules for a heterogeneous fleet of ships while determining the cargo routing and the speed for all relevant port pair/ship combinations. Transshipment is allowed in ports with transshipment capabilities. The service frequency is fixed at one week...
Nature-Inspired and Energy Efficient Route Planning
DEFF Research Database (Denmark)
Schlichtkrull, Anders; Christensen, J. B. S.; Feld, T.;
2015-01-01
Cars are responsible for substantial CO2 emission worldwide. Computers can help solve this problem by computing shortest routes on maps. A good example of this is the popular Google Maps service. However, such services often require the order of the stops on the route to be fixed. By not enforcing...
Trdlicka, J.; Hanzalek, Z.
2010-01-01
This work proposes a distributed algorithm for energy optimal routing in a wireless sensor network. The routing problem is described as a mathematical problem by the minimum-cost multi-commodity network flow problem. Due to the separability of the problem, we use the duality theorem to derive the distributed algorithm. The algorithm computes the energy optimal routing in the network without any central node or knowledge of the whole network structure. Each node only needs to know the flow whi...
Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air
DEFF Research Database (Denmark)
Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan;
2014-01-01
Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating...
On arc efficiency in gas tungsten arc welding
Directory of Open Access Journals (Sweden)
Nils Stenbacka
2013-12-01
Full Text Available The aim of this study was to review the literature on published arc efficiency values for GTAW and, if possible, propose a narrower band. Articles between the years 1955 - 2011 have been found. Published arc efficiency values for GTAW DCEN show to lie on a wide range, between 0.36 to 0.90. Only a few studies covered DCEP - direct current electrode positive and AC current. Specific information about the reproducibility in calorimetric studies as well as in modeling and simulation studies (considering that both random and systematic errors are small was scarce. An estimate of the average arc efficiency value for GTAW DCEN indicates that it should be about 0.77. It indicates anyway that the GTAW process with DCEN is an efficient welding method. The arc efficiency is reduced when the arc length is increased. On the other hand, there are conflicting results in the literature as to the influence of arc current and travel speed.
Multihop Wireless Networks Opportunistic Routing
Zeng, Kai; Li, Ming
2011-01-01
This book provides an introduction to opportunistic routing an emerging technology designed to improve the packet forwarding reliability, network capacity and energy efficiency of multihop wireless networks This book presents a comprehensive background to the technological challenges lying behind opportunistic routing. The authors cover many fundamental research issues for this new concept, including the basic principles, performance limit and performance improvement of opportunistic routing compared to traditional routing, energy efficiency and distributed opportunistic routing protocol desig
38: Optimization of electron arc therapy doses by dynamic collimator control
International Nuclear Information System (INIS)
The problem of delivering a uniform dose to a large curved surface such as a patient's chest wall has been addressed by the technique of electron arc therapy. Prospective computer simulations show that a dramatic improvement in dose uniformity can, in many clinical situations, be achieved by dynamic shaping of the electron arc collimator, under computer control, as a function of gantry angle and distance superior or inferior to the central plane. Computer optimization techniques applied to the design of a multivane dynamic electron arc collimator is presented, along with representative treatment plans resulting from inclusion of this dynamic technique in electron arc therapy. 17 refs.; 5 figs
Hoenicke, Dirk
2014-12-02
Disclosed are a unified method and apparatus to classify, route, and process injected data packets into a network so as to belong to a plurality of logical networks, each implementing a specific flow of data on top of a common physical network. The method allows to locally identify collectives of packets for local processing, such as the computation of the sum, difference, maximum, minimum, or other logical operations among the identified packet collective. Packets are injected together with a class-attribute and an opcode attribute. Network routers, employing the described method, use the packet attributes to look-up the class-specific route information from a local route table, which contains the local incoming and outgoing directions as part of the specifically implemented global data flow of the particular virtual network.
Delaney, Adam Vai
2011-07-01
Born in Port Moresby, Papua New Guinea, the author had a 20 year career in diplomacy, political affairs, and development policy analysis at the Pacific Islands Forum, the United Nations in New York; the Prime Minister's Department in Papua New Guinea (PNG) and in the Foreign Ministry of PNG. He has also been involved in theatre for over a decade in PNG, and participated in a three-month program at the Eugene O'Neill Theatre Center in Connecticut, USA. He is currently the Business Development Manager at the Torres Strait Regional Authority (Commonwealth) on Thursday Island. Since 1975 the Australian government's overseas development policy has supported various sectoral programs in its neighbouring countries, in particular Papua New Guinea and the Solomon Islands. The "creative" field has not been prominent in this strategy. While natural resources and the sports sectors have gained much greater attention, in terms of being viable international commercial enterprises, the arts, have remained stagnant. In this paper the need for joint programs genuinely supporting "wellbeing" and promoting social enterprise throughout the "arc of opportunity" is described to harness Melanesian creativity to compete successfully in world-markets, starting with penetration of the largest economy at its door-step: Australia.
DEFF Research Database (Denmark)
Christensen, Ann-Dorte; Jensen, Sune Qvotrup
2011-01-01
arguing that there is a dynamic interplay between roots and routes in people's lives. The empirical point of departure is narratives about roots and routes by ethnic minorities settled in Aalborg East, an underprivileged neighbourhood in northern Denmark. One of the main findings is a gap between the...... somewhat paradoxical finding is that it appears to be more difficult for transnational migrants to maintain their roots in the country of origin when they go back than it was to establish new roots in the host country...
Institute of Scientific and Technical Information of China (English)
2008-01-01
San Francisco changes Olympic flame route due to security fears The city of San Francisco,the only North American stop for the 2008 Beijing Olympic torch,surprised thousands of supporters,demon- strators and visitors on April 9,by com- pletely changing the planned torch route at the last minute without notification. As scheduled,the torch was expected to start from the McCovey Cove in the south- east of the city at 1:00 p.m.before heading along the waterfront northbound to famous tourist spot Fisherman’s Wharf and finally
A New Approach to VC Routing in ATM Networks
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A new ant-algorithm-based routing approach is proposed for the VC routing problem with considering the comprehensive effect between the resource utilization and the load balance in ATM networks. In the approach, the backup paths are calculated first, and then an ant algorithm based on the ability of ants to find the shortest path between their nest and the food source during their searching food, is constructed to optimize the VC global route.Simulation results show that the proposed approach can realize VC routing effectively according to the current traffic states in the networks and the user-specified delay requirements.
STUDY ON THE PRESSURE IN PLASMA ARC
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The axial pressure in plasma arc is measured under different conditions. The effects of the parameters, such as welding current, plasma gas flow rate, electrode setback and arc length, on the pressure in plasma arc are investigated and quantitative analyzed to explain the relationship between the quality of weld and the matching of parameters in plasma arc welding process.
Detours in Scope-Based Route Planning
Hliněný, Petr
2012-01-01
We study a dynamic scenario of the static route planning problem in road networks. Particularly, we put accent on the most practical dynamic case - increased edge weights (up to infinity). We show how to enhance the scope-based route planning approach presented at ESA'11 to intuitively by-pass closures by detours. Three variants of a detour "admissibility" are presented - from a simple one with straightforward implementation through its enhanced version to a full and very complex variant variant which always returns an optimal detour.
Mathematical Aspects of Network Routing Optimization
Oliveira, Carlos AS
2011-01-01
Before the appearance of broadband links and wireless systems, networks have been used to connect people in new ways. Now, the modern world is connected through large-scale, computational networked systems such as the Internet. Because of the ever-advancing technology of networking, efficient algorithms have become increasingly necessary to solve some of the problems developing in this area. "Mathematical Aspects of Network Routing Optimization" focuses on computational issues arising from the process of optimizing network routes, such as quality of the resulting links and their reli
Optimized QoS Routing Algorithm
Institute of Scientific and Technical Information of China (English)
石明洪; 王思兵; 白英彩
2004-01-01
QoS routing is one of the key technologies for providing guaranteed service in IP networks. The paper focuses on the optimization problem for bandwidth constrained QoS routing, and proposes an optimal algorithm based on the global optimization of path bandwidth and hop counts. The main goal of the algorithm is to minimize the consumption of network resource, and at the same time to minimize the network congestion caused by irrational path selection. The simulation results show that our algorithm has lower call blocking rate and higher throughput than traditional algorithms.
Efficient Networks Communication Routing Using Swarm Intelligence
Directory of Open Access Journals (Sweden)
Koushal Kumar
2012-11-01
Full Text Available As demonstrated by natural biological swarm’s collective intelligence has an abundance of desirable properties for problem-solving like in network routing. The focus of this paper is in the applications of swarm based intelligence in information routing for communication networks. As we know networks are growing and adopting new platforms as new technologies comes. Also according to new demands and requirements networks topologies and its complexity is increasing with time. Thus it is becoming very difficult to maintain the quality of services and reliability of the networks using current Networks routing algorithms. Thus Swarm intelligence (SI is the collective behavior of decentralized self-organized systems, natural or artificial. The concept is employed in work on artificial intelligence. A new class of algorithms, inspired by swarm intelligence is currently being developed that can potentially solve numerous problems of modern communications networks. These algorithms rely on the interaction of a multitude of simultaneously interacting agents. In this paper we give disadvantages of previously used network routing algorithms and how we can apply swarm intelligence to overcome these problems.
Route Challenging Scheme Using Friend Based Rating in MANETs
Directory of Open Access Journals (Sweden)
S. Shantha Meena
2013-04-01
Full Text Available Security and Route identification are the major challenges in MANETs. Existing neighbour based routing algorithms provide route based on the quantity of data transferred [1] which may result in congestion. This is because the route having higher amount of transaction is preferred every time. In this paper we propose a Friend Based Routing algorithm [FBRA] for solving this problem. Here, the appropriate route is found not only based on the quantity of data transferred but also considers RSS and RTT. For providing re-authentication to the nodes in the network, FBRA uses Zero-Knowledge Protocol. The main advantage of this method is providing enhanced security and distinguishes the malicious nodes from the trusted nodes in the network.
Newton's Radii, Maupertuis' Arc Length, and Voltaire's Giant
Simoson, Andrew J.
2011-01-01
Given two arc length measurements along the perimeter of an ellipse--one taken near the long diameter, the other taken anywhere else--how do you find the lengths of major and minor axes? This was a problem of great interest from the time of Newton's "Principia" until the mid-eighteenth century when France launched twin geodesic expeditions--one to…
Whirlpool routing for mobility
Lee, Jung Woo
2010-01-01
We present the Whirlpool Routing Protocol (WARP), which efficiently routes data to a node moving within a static mesh. The key insight in WARP\\'s design is that data traffic can use an existing routing gradient to efficiently probe the topology, repair the routing gradient, and communicate these repairs to nearby nodes. Using simulation, controlled testbeds, and real mobility experiments, we find that using the data plane for topology maintenance is highly effective due to the incremental nature of mobility updates. WARP leverages the fact that converging flows at a destination make the destination have the region of highest traffic. We provide a theoretical basis for WARP\\'s behavior, defining an "update area" in which the topology must adjust when a destination moves. As long as packets arrive at a destination before it moves outside of the update area, WARP can repair the topology using the data plane. Compared to existing protocols, such as DYMO and HYPER, WARP\\'s packet drop rate is up to 90% lower while sending up to 90% fewer packets.
Marietta Schupp, EMBL Photolab
2008-01-01
Dr Sabine Hentze, specialist in human genetics, giving an Insight Lecture entitled "Human Genetics – Diagnostics, Indications and Ethical Issues" on 23 September 2008 at EMBL Heidelberg. Activities in a achool in Budapest during a visit of Angela Bekesi, Ambassadors for the SET-Routes programme.
CERN audiovisual service
2009-01-01
The SET-Routes programme, launched in 2007 with the goal of attracting girls and young women to careers in science, came to an end in April this year. The result of a collaboration between EMBL, EMBO and CERN, the programme established a network of "ambassadors", women scientists who went out to talk about their careers in science at schools and universities across Europe.
LBR: Load Balancing Routing Algorithm for Wireless Sensor Networks
Daabaj, Khaled; Dixon, Mike; Koziniec, Terry
2010-06-01
Homogeneous wireless sensor networks (WSNs) are organized using identical sensor nodes, but the nature of WSNs operations results in an imbalanced workload on gateway sensor nodes which may lead to a hot-spot or routing hole problem. The routing hole problem can be considered as a natural result of the tree-based routing schemes that are widely used in WSNs, where all nodes construct a multi-hop routing tree to a centralized root, e.g., a gateway or base station. For example, sensor nodes on the routing path and closer to the base station deplete their own energy faster than other nodes, or sensor nodes with the best link state to the base station are overloaded with traffic from the rest of the network and experience a faster energy depletion rate than their peers. Routing protocols for WSNs are reliability-oriented and their use of reliability metric to avoid unreliable links makes the routing scheme worse. However, none of these reliability oriented routing protocols explicitly uses load balancing in their routing schemes. Since improving network lifetime is a fundamental challenge of WSNs, we present, in this chapter, a novel, energy-wise, load balancing routing (LBR) algorithm that addresses load balancing in an energy efficient manner by maintaining a reliable set of parent nodes. This allows sensor nodes to quickly find a new parent upon parent loss due to the existing of node failure or energy hole. The proposed routing algorithm is tested using simulations and the results demonstrate that it outperforms the MultiHopLQI reliability based routing algorithm.
Directory of Open Access Journals (Sweden)
Hong-Hsu Yen
2009-06-01
Full Text Available In wireless sensor networks, data aggregation routing could reduce the number of data transmissions so as to achieve energy efficient transmission. However, data aggregation introduces data retransmission that is caused by co-channel interference from neighboring sensor nodes. This kind of co-channel interference could result in extra energy consumption and significant latency from retransmission. This will jeopardize the benefits of data aggregation. One possible solution to circumvent data retransmission caused by co-channel interference is to assign different channels to every sensor node that is within each other’s interference range on the data aggregation tree. By associating each radio with a different channel, a sensor node could receive data from all the children nodes on the data aggregation tree simultaneously. This could reduce the latency from the data source nodes back to the sink so as to meet the user’s delay QoS. Since the number of radios on each sensor node and the number of non-overlapping channels are all limited resources in wireless sensor networks, a challenging question here is to minimize the total transmission cost under limited number of non-overlapping channels in multi-radio wireless sensor networks. This channel constrained data aggregation routing problem in multi-radio wireless sensor networks is an NP-hard problem. I first model this problem as a mixed integer and linear programming problem where the objective is to minimize the total transmission subject to the data aggregation routing, channel and radio resources constraints. The solution approach is based on the Lagrangean relaxation technique to relax some constraints into the objective function and then to derive a set of independent subproblems. By optimally solving these subproblems, it can not only calculate the lower bound of the original primal problem but also provide useful information to get the primal feasible solutions. By incorporating these
Robust routing mechanisms for intradomain traffic engineering in dynamic networks
Casas Hernandez, Pedro; Larroca, Federico; Vaton, Sandrine
2009-01-01
Internet traffic is highly dynamic and difficult to predict in current network scenarios. This makes of traffic engineering (TE) a very challenging task for network management and resources optimization. We study the problem of intradomain routing optimization under this traffic uncertainty. Recent works have proposed robust optimization techniques to tackle the problem, conceiving the robust routing (RR) approach. RR copes with traffic uncertainty in an off-line preemptive fashion, computing...
Mobile Anonymous Trust Based Routing Using Ant Colony Optimization
R. KALPANA; N. Rengarajan
2012-01-01
Problem statement: Ad hoc networks are susceptible to malicious attacks through denial of services, traffic analysis and spoofing. The security of the ad hoc routing protocol depends upon encryption, authentication, anonymity and trust factors. End-to-end security of data is provided by encryption and authentication, topology information of the nodes can be obtained by studying traffic and routing data. This security problem of ad hoc network is addressed by the use of anonymity mechanisms an...
Fuzzy Optimized Metric for Adaptive Network Routing
Directory of Open Access Journals (Sweden)
Ahmad Khader Haboush
2012-04-01
Full Text Available Network routing algorithms used today calculate least cost (shortest paths between nodes. The cost of a path is the sum of the cost of all links on that path. The use of a single metric for adaptive routing is insufficient to reflect the actual state of the link. In general, there is a limitation on the accuracy of the link state information obtained by the routing protocol. Hence it becomes useful if two or more metrics can be associated to produce a single metric that can describe the state of the link more accurately. In this paper, a fuzzy inference rule base is implemented to generate the fuzzy cost of each candidate path to be used in routing the incoming calls. This fuzzy cost is based on the crisp values of the different metrics; a fuzzy membership function is defined. The parameters of these membership functions reflect dynamically the requirement of the incoming traffic service as well as the current state of the links in the path. And this paper investigates how three metrics, the mean link bandwidth, queue utilization and the mean link delay, can be related using a simple fuzzy logic algorithm to produce a optimized cost of the link for a certain interval that is more „precise‟ than either of the single metric, to solve routing problem .
Routing algorithms in networks-on-chip
Daneshtalab, Masoud
2014-01-01
This book provides a single-source reference to routing algorithms for Networks-on-Chip (NoCs), as well as in-depth discussions of advanced solutions applied to current and next generation, many core NoC-based Systems-on-Chip (SoCs). After a basic introduction to the NoC design paradigm and architectures, routing algorithms for NoC architectures are presented and discussed at all abstraction levels, from the algorithmic level to actual implementation. Coverage emphasizes the role played by the routing algorithm and is organized around key problems affecting current and next generation, many-core SoCs. A selection of routing algorithms is included, specifically designed to address key issues faced by designers in the ultra-deep sub-micron (UDSM) era, including performance improvement, power, energy, and thermal issues, fault tolerance and reliability. · Provides a comprehensive overview of routing algorithms for Networks-on-Chip and NoC-based, manycore systems; · Describe...
Low Carbon Footprint Routes for Bird Watching
Directory of Open Access Journals (Sweden)
Wei-Ta Fang
2015-03-01
Full Text Available Bird watching is one of many recreational activities popular in ecotourism. Its popularity, therefore, prompts the need for studies on energy conservation. One such environmentally friendly approach toward minimizing bird watching’s ecological impact is ensuring a reduced carbon footprint by using an economic travel itinerary comprising a series of connected routes between tourist attractions that minimizes transit time. This study used a travel-route planning approach using geographic information systems to detect the shortest path, thereby solving the problems associated with time-consuming transport. Based on the results of road network analyses, optimal travel-route planning can be determined. These methods include simulated annealing (SA and genetic algorithms (GA. We applied two algorithms in our simulation research to detect which one is an appropriate algorithm for running carbon-routing algorithms at the regional scale. SA, which is superior to GA, is considered an excellent approach to search for the optimal path to reduce carbon dioxide and high gasoline fees, thereby controlling travel time by using the shortest travel routes.
Control of arc plasma torches: compensation of operational enthalpy drifts
Energy Technology Data Exchange (ETDEWEB)
Oliver, D H; Alexieva, J; Djakov, B E; Enikov, R [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Dimitrov, D [Centre of Biomedical Engineering, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 105, 1113 Sofia (Bulgaria)], E-mail: dick.oliver@gmail.com
2008-05-01
In arc plasma torches electrode wear is the main reason for slow changes in the electrical and thermal torch characteristics. Such effects hinder technological applications of this type of plasma torches whenever the enthalpy must be maintained at a fixed level, or varied as needed. To solve this problem, a new method and algorithm for torch control are proposed. The time evolution of the arc current, voltage and thermal power loss of the torch are recorded. The values measured are used to find the required value of the enthalpy.
Routing-based synthesis of digital microfluidic biochips
DEFF Research Database (Denmark)
Maftei, Elena; Pop, Paul; Madsen, Jan
2012-01-01
Microfluidic biochips are replacing the conventional biochemical analyzers, and are able to integrate on-chip all the necessary functions for biochemical analysis. The “digital” biochips are manipulating liquids as discrete droplets on a two-dimensional array of electrodes. Basic microfluidic...... of virtual devices and allow the droplets to move on the chip on any route during operation execution. Thus, the synthesis problem is transformed into a routing problem. We develop an algorithm based on a Greedy Randomized Adaptive Search Procedure (GRASP) and we show that routing-based synthesis leads...
Sze, Robert C.; Bigio, Irving J.
2003-07-15
A high pressure neon arc lamp and method of using the same for photodynamic therapies is provided. The high pressure neon arc lamp includes a housing that encloses a quantity of neon gas pressurized to about 500 Torr to about 22,000 Torr. At each end of the housing the lamp is connected by electrodes and wires to a pulse generator. The pulse generator generates an initial pulse voltage to breakdown the impedance of the neon gas. Then the pulse generator delivers a current through the neon gas to create an electrical arc that emits light having wavelengths from about 620 nanometers to about 645 nanometers. A method for activating a photosensitizer is provided. Initially, a photosensitizer is administered to a patient and allowed time to be absorbed into target cells. Then the high pressure neon arc lamp is used to illuminate the target cells with red light having wavelengths from about 620 nanometers to about 645 nanometers. The red light activates the photosensitizers to start a chain reaction that may involve oxygen free radicals to destroy the target cells. In this manner, a high pressure neon arc lamp that is inexpensive and efficiently generates red light useful in photodynamic therapy is provided.
The Banda Arc subduction enigma
Spakman, Wim; Hall, Robert
2010-05-01
The spectacularly curved Banda arc comprises young oceanic crust enclosed by a volcanic inner arc, outer arc islands, and a trough parallel to the Australian continental margin. Seismicity defines a spoon-shaped lithospheric fold in the upper mantle for which there are two contrasting explanations: deformation of a single subducted slab, or two different slabs subducted from north and south. We show that the Banda arc resulted from subduction of a single slab. Based on geology and seismic tomography, we argue that the arc formed since 15 Ma by subduction of a Jurassic oceanic embayment within the Australian plate. Viewed in an Atlantic-Indian hotspot reference frame, the stationary E-W striking Java trench propagated ESE into the Banda embayment by hinge rollback. Extension of the upper plate formed oceanic crust in the present Banda Sea between stretched continental crust of Australian origin. Slab morphology depends primarily on the geometry of the continental margin enclosing the embayment. Our model explains the first order tectonic development of the Banda region and links slab deformation to absolute plate motion.
Raja, Umar Waqas; Mustafa, Bilal
2010-01-01
Vehicular Ad Hoc Network (VANET) is a sub class of mobile ad hoc networks. VANET provides wireless communication among vehicles and vehicle to road side equipments. The communication between vehicles is used for safety, comfort and for entertainment as well. The performance of communication depends on how better the routing takes place in the network. Routing of data depends on the routing protocols being used in network. In this study we investigated about different ad hoc routing protocols ...
Innovation in electric arc furnaces scientific basis for selection
Toulouevski, Yuri N
2013-01-01
This book equips a reader with knowledge necessary for critical analysis of innovations in electric arc furnaces and helps to select the most effective ones and for their successful implementation. The book also covers general issues related to history of development, current state and prospects of steelmaking in Electric Arc Furnaces. Therefore, it can be useful for everybody who studies metallurgy, including students of colleges and universities. The modern concepts of mechanisms of Arc Furnace processes are are discussed in the book at the level sufficient to solve practical problems: To help readers lacking knowledge required in the field of heat transfer as well as hydro-gas dynamics, it contains several chapters which provide the required minimum of information in these fields of science. In order to better assess different innovations, the book describes experience of the application of similar innovations in open-hearth furnaces and oxygen converters. Some promising ideas on key issues regarding int...
Direct Current Electric Arc-Electroslag Ladle Furnace
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In order to solve the high consumption problem of small capacity ladle furnace (LF), the operation principle and control method of the DC arc and electroslag heating ladle furnace are introduced. With only one arcing electrode, the distance between the arc and the wall of ladle is enlarged, and consequently the consumption of the ladle refractory is decreased. In the invention, a signal electrode is embedded in the refractory lining of the ladle, which contacts directly with the liquid steel and the ladle shell. Two graphite anode ends are submerged in the slag layer. The signal electrode is used as voltage reference during refining process. The electroslag voltage between anode end and liquid steel is applied to control the depth of anode end in the slag layer during the refining process with this ladle furnace.
Alternative iron making routes
Energy Technology Data Exchange (ETDEWEB)
Kaushik, P.; Sharma, T. [Indian School of Mines, Dhanbad (India)
2002-07-01
The versatile route of iron production 'blast furnace' technique is being replaced by widely accepted Corex technology, Midrex process using Fastmelt ironmaking, eco-friendly Romelt process, more innovative Ausmelt & Hismelt technology, TATA KORF Mini blast furnace improvement, 'quickest iron through Orbiting Plasma', Direct iron ore smelting process, Conred, AISI-Hyl, Inred processes, Direct iron ore reduction methods, their comparison and proposed modifications. 18 refs., 11 figs., 14 tabs.
Cutting path as a Rural Postman Problem: solutions by Memetic Algorithms
Directory of Open Access Journals (Sweden)
Ana Maria Rodrigues
2012-01-01
Full Text Available The Rural Postman Problem (RPP is a particular Arc Routing Problem (ARP which consists of determining a minimum cost circuit on a graph so that a given subset of required edges is traversed. The RPP is an NP-hard problem with significant real-life applications. This paper introduces an original approach based on Memetic Algorithms - the MARP algorithm - to solve the RPP and, also deals with an interesting Industrial Application, which focuses on the path optimization for component cutting operations. Memetic Algorithms are a class of Metaheuristics which may be seen as a population strategy that involves cooperation and competition processes between population elements and integrates “social knowledge”, using a local search procedure. The MARP algorithm is tested with different groups of instances and the results are compared with those gathered from other publications. MARP is also used in the context of various real-life applications.
CO2 laser-micro plasma arc hybrid welding for galvanized steel sheets
Institute of Scientific and Technical Information of China (English)
C. H. KIM; Y. N. AHN; J. H. KIM
2011-01-01
A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal. which is steel. In the autogenous laser welding,the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-heat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap.The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces.Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.
Novel multi-path routing scheme for UWB Ad hoc network
Institute of Scientific and Technical Information of China (English)
XU Ping-ping; YANG Cai-yu; SONG Shu-qing; BI Guang-guo
2005-01-01
The routing protocols play an important role for ad hoc networks performance. As some problems with DSR,SMR, and AMR protocols were analyzed, a new routing protocol suitable for UWB Ad hoc networks was proposed in this paper. The new routing protocol utilize an act of orientation of UWB and tries to get sufficient route information and decrease the network load caused by route discovery at the same time. Simulation results show that the routing load of the new protocol is lower and throughput is higher than that of DSR. While the node's mobility increases, these advantages become more obvious.
Electronic route information panels (DRIPs).
2008-01-01
Also in the Netherlands, the term Dynamic Route Information Panel (DRIP) is used for an electronic route information panel. A DRIP usually indicates whether there are queues on the various routes to a particular destination and how long they are. On certain locations DRIPS also give the estimated tr
Utilization of steel melting electric arc furnace slag for development of vitreous ceramic tiles
Indian Academy of Sciences (India)
Ritwik Sarkar; Nar Singh; Swapan Kumar Das
2010-06-01
Steel melting through electric arc furnace route is gaining popularity due to its many advantages, but generates a new waste, electric arc furnace slag, which is getting accumulated and land/mine filling and road construction are the only utilization. This slag has been tried to be value added and utilized to develop vitreous ceramic tiles. Slag, to the extent of 30–40 wt% with other conventional raw materials, were used for the development in the temperature range 1100–1150°C. The fired products showed relatively higher density with shorter firing range and good strength properties. Microstructural and EDAX studies were also done to evaluate the developed products.
Effective local dynamic routing strategy for air route networks
Institute of Scientific and Technical Information of China (English)
Wu Wenjun; Zhao Lingxi
2015-01-01
With the rapid development of air transportation, network service ability has attracted a lot of attention in academe. Aiming to improve the throughput of the air route network (ARN), we propose an effective local dynamic routing strategy in this paper. Several factors, such as the rout-ing distance, the geographical distance and the real-time local traffic, are taken into consideration. When the ARN is in the normal free-flow state, the proposed strategy can recover the shortest path routing (SPR) strategy. When the ARN undergoes congestion, the proposed strategy changes the paths of flights based on the real-time local traffic information. The throughput of the Chinese air route network (CARN) is evaluated. Results confirm that the proposed strategy can significantly improve the throughput of CARN. Meanwhile, the increase in the average flying distance and time is tiny. Results also indicate the importance of the distance related factors in a routing strategy designed for the ARN.
Occurrence of radon in the Polish underground tourist routes
Directory of Open Access Journals (Sweden)
Jerzy Olszewski
2015-08-01
Full Text Available Background: There are about 200 underground tourist routes in Poland. There are caves, mines or underground structures. This paper presents the results of the research intended to identify the extent of the occurrence of radon concentrations in underground areas of tourist routes. Material and Methods: We conducted the measurement of periodic concentrations of radon (1–2 months in the summer using type Tastrak trace detectors. We determined the average concentrations of radon in air in 66 underground tourist routes in Poland. Results: The research results comprise 259 determinations of average radon concentrations in 66 routes. The arithmetic average of the results was 1610 Bqm–3, and the maximum measured concentration was over 20 000 Bqm–3. The minimum concentration was 100 Bqm–3 (threshold method considering the arithmetic average of the measurements. It was found that in 67% of the routes, the average concentration of radon has exceeded 300 Bqm–3 and in 22 underground routes it exceeded 1000 Bqm–3. Conclusions: Radon which occurs in many Polish underground tourist routes may be an organizational, legal and health problem. It is necessary to develop a program of measures to reduce radon concentrations in underground routes, especially routes located in the former mines. Med Pr 2015;66(4:557–563
AODV routing overhead analysis based on link failure probability in MANET
Institute of Scientific and Technical Information of China (English)
ZHANG Qin-juan; WU Mu-qing; ZHEN Yan; SHANG Cui-li
2010-01-01
This article puts forward an Ad-hoc on-demand distance vector routing(AODV)routing overhead analysis method in mobile Ad-hoc network(MANET).Although multiple routing protocols have been proposed to improve the performance,scarcely any paper analyzed the routing overhead caused by routing setup and maintenance processes in mathematical way.Routing overhead consumes part of network resources and limits the supported traffic in the network.For on-demand routing protocols like AODV,the routing overhead depends on the link failure probability to a great extent.This article analyzes the collision probability caused by hidden-node problem and the impact on link failure probability.In chain and rectangle scenarios,it presents a mathematical analysis of the theoretical routing overhead of AODV protocol based on link failure probability.Simulations on OPNET 14.5platform match well with the theoretical derivation which confirms the effectiveness of the analysis method.
Unzipping of the volcano arc, Japan
Stern, R.J.; Smoot, N.C.; Rubin, M.
1984-01-01
A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: 1. (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. 2. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. 3. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin. ?? 1984.
Robustness of airline route networks
Lordan, Oriol; Sallan, Jose M.; Escorihuela, Nuria; Gonzalez-Prieto, David
2016-03-01
Airlines shape their route network by defining their routes through supply and demand considerations, paying little attention to network performance indicators, such as network robustness. However, the collapse of an airline network can produce high financial costs for the airline and all its geographical area of influence. The aim of this study is to analyze the topology and robustness of the network route of airlines following Low Cost Carriers (LCCs) and Full Service Carriers (FSCs) business models. Results show that FSC hubs are more central than LCC bases in their route network. As a result, LCC route networks are more robust than FSC networks.
Pedestrian Route Choice by Iterated Equilibrium Search
Kretz, Tobias; Hofsäß, Ingmar
2014-01-01
In vehicular traffic planning it is a long standing problem how to assign demand such on the available model of a road network that an equilibrium with regard to travel time or generalized costs is realized. For pedestrian traffic this question can be asked as well. However, as the infrastructure of pedestrian dynamics is not a network (a graph), but two-dimensional, there is in principle an infinitely large set of routes. As a consequence none of the iterating assignment methods developed for road traffic can be applied for pedestrians. In this contribution a method to overcome this problem is briefly summarized and applied with an example geometry which as a result is enhanced with routes with intermediate destination areas of certain shape. The enhanced geometry is used in some exemplary assignment calculations.
On the Lorentzian route to Relativity
Gürel, Atilla
2011-01-01
We discuss pedagogical problems associated with the conventional approach in teaching relativity and the potential value of "Lorentzian route to relativity" for addressing these pedagogical problems. We think that Lorentzian approach may be valuable part of an introduction to relativity but the historical route should be followed up to its end. It must namely include Einstein's application of Occam's razor in reinterpreting Lorentz transformations kinematically and the discussion of the central role of the evolution from Lorentz's "local time" to relativity of simultaneity. We discuss also what Occam's razor is not and why it should not cut "too deeply or too permanently". Some misleading remarks in relativity text books concerning for example Kennedy Thorndike experiment and Trouton-Noble experiment indicate the not uncommon lack of awareness about the degree observational equivalence between prerelativistic (Lorentzian) and relativistic viewpoints as far as special relativistic experiments are considered. K...
Application of Harmony Search to Vehicle Routing
Directory of Open Access Journals (Sweden)
Zong W. Geem
2005-01-01
Full Text Available A phenomenon-inspired meta-heuristic algorithm, harmony search, imitating music improvisation process, is introduced and applied to vehicle routing problem, then compared with one of the popular evolutionary algorithms, genetic algorithm. The harmony search algorithm conceptualized a group of musicians together trying to search for better state of harmony. This algorithm was applied to a test traffic network composed of one bus depot, one school and ten bus stops with demand by commuting students. This school bus routing example is a multi-objective problem to minimize both the number of operating buses and the total travel time of all buses while satisfying bus capacity and time window constraints. Harmony search could find good solution within the reasonable amount of time and computation.
Dynamic Route Planning in Vehicular Networks based on Future Travel Time Estimation
Santi, Paolo; Fontanelli, Stefano; Bini, Enrico
2010-01-01
Traffic congestion wastes time, energy, and causes pollution. In this paper, We propose an application taking advantage of vehicular communications, namely dynamic route planning. In dynamic route planning, the route from a travel origin to its destination, instead of being statically determined at the travel starting time, is periodically recomputed according to real-time traffic information. Estimating future travel time is indeed central to the dynamic route planning problem. Since knowing...
An Evolutionary Real-Time 3D Route Planner for Aircraft
Institute of Scientific and Technical Information of China (English)
郑昌文; 丁明跃; 周成平
2003-01-01
A novel evolutionary route planner for aircraft is proposed in this paper. In the new planner, individual candidates are evaluated with respect to the workspace, thus the computation of the configuration space is not required. By using problem-specific chromosome structure and genetic operators, the routes are generated in real time,with different mission constraints such as minimum route leg length and flying altitude, maximum turning angle, maximum climbing/diving angle and route distance constraint taken into account.
Institute of Scientific and Technical Information of China (English)
曾云; 刘宗武
2011-01-01
The paper studies the optimization of logistics distribution routes based on the theory of complex networks and, in view of the complex character of the distribution network, builds a distribution network graph model which is solved through dynamic programming method. An empirical example is presented at the end to verify the feasibility of the model.%在复杂网络理论的基础上研究物流配送路径优化问题,结合配送网络的复杂性特点,构建配送网络图模型,利用动态规划方法求解,最终通过实例进行验证.
Personal continuous route pattern mining
Institute of Scientific and Technical Information of China (English)
Qian YE; Ling CHEN; Gen-cai CHEN
2009-01-01
In the daily life, people often repeat regular routes in certain periods. In this paper, a mining system is developed to find the continuous route patterns of personal past trips. In order to count the diversity of personal moving status, the mining system employs the adaptive GPS data recording and five data filters to guarantee the clean trips data. The mining system uses a client/server architecture to protect personal privacy and to reduce the computational load. The server conducts the main mining procedure but with insufficient information to recover real personal routes. In order to improve the scalability of sequential pattern mining, a novel pattern mining algorithm, continuous route pattern mining (CRPM), is proposed. This algorithm can tolerate the different disturbances in real routes and extract the frequent patterns. Experimental results based on nine persons' trips show that CRPM can extract more than two times longer route patterns than the traditional route pattern mining algorithms.
Congestion Free Routing in Adhoc Networks
Directory of Open Access Journals (Sweden)
V. Sankaranarayanan
2012-01-01
Full Text Available Problem statement: A Mobile Ad-Hoc Network (MANET is a temporary network; the mobile devices in an ad-hoc network are communicating through wireless links without any pre-existing infrastructure. The one major problem of this network is network congestion, it may take place at any intermediate nodes when data packets are traveling from source to destination. The major problems of congestion or high data loss, increasing End to End and retransmission packets which affects the overall network performance. The main goal of congestion control is to effectively utilize the existing network resources and maintain the network load below the capacity. Approach: This study presents the Congestion Free Routing in Adhoc networks (CFR, based on dynamically estimated mechanism to monitor network congestion by calculating the average queue length at the node level. While using the average queue length, the nodes congestion status divided into the three zones (safe zone, likely to be congested zone and congested zone. CFR utilizes the non-congested neighbors and initiates route discovery mechanism to discover a congestion free route between source and destination. This path becomes a core path between source and destination. To maintain the congestion free status, the nodes which are helping data packet transmission periodically calculate their congestion status at the node level. When a core node is noticed that it fell in to likely to congested zone and alerts to its neighbors. The predecessor core path node is aware of this situation and initiates an alternate path discovery mechanism to a destination. Finally it discovers a new congestion free route to the destination. Results: The assessment between CFR and AODV was conducted by using the Ns-2 simulator. The simulation results confirmed that the CFR improved packet delivery ratio, reduction of End to End delay and control packets. Conclusion: Our proposed technique solved the congestion problems in a
Locating Depots for Capacitated Vehicle Routing
DEFF Research Database (Denmark)
Gørtz, Inge Li; Nagarajan, Viswanath
2011-01-01
We study a location-routing problem in the context of capacitated vehicle routing. The input to k-LocVRP is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so...... median forest, which leads to a (12+E)-approximation algorithm for k-LocVRP, for any constant E > 0. The algorithm for k median forest is t-swap local search, and we prove that it has locality gap 3 + 2 t ; this generalizes the corresponding result for k median [3]. Finally we consider the k median...... forest problem when there is a different (unrelated) cost function c for the MST part, i.e. the objective is Eu∈V d(u, S) + c(MST(V/S) ). We show that the locality gap for this problem is unbounded even under multi-swaps, which contrasts with the c = d case. Nevertheless, we obtain a constant...
1972-01-01
The positioning system for the hooded arc ion-source, shown prior to mounting, consists of four excentric shafts to locate the ion-source and central electrodes. It will be placed on the axis of the SC and introduced into the vacuum tank via the air locks visible in the foreground.
Craniospinal irradiation using Rapid Arc
Energy Technology Data Exchange (ETDEWEB)
Fandino, J. M.; Silva, M. C.; Marino, A.; Candal, A.; Diaz, I.; Fernandez, C.; Gesto, C.; Izquierdo, P.; Losada, C.; Poncet, M.; Soto, M.; Triana, G.
2013-07-01
Cranio-Spinal Irradiation is technically very challenging, historically field edge matching is needed because of the mechanical limitations of standard linear accelerators. The purpose of this study is to assess the Volumetric Arc Therapy as a competitive technique for Cranio-Spinal Irradiation compared to the conventional 3D Conformal Radiotherapy technique. (Author)
STRUVE arc and EUPOS® stations
Lasmane, Ieva; Kaminskis, Janis; Balodis, Janis; Haritonova, Diana
2013-04-01
The Struve Geodetic Arc was developed in Years 1816 to 1855, 200 years ago. Historic information on the points of the Struve Geodetic Arc are included in the UNESCO World Heritage list in 2005. Nevertheless, the sites of many points are still not identified nor included in the data bases nowadays. Originally STRUVE arc consisted of 258 main triangles with 265 triangulation points. Currently 34 of the original station points are identified and included in the in the UNESCO World Heritage list. identified original measurement points of the Meridian Arc are located in Sweden (7 points), Norway (15), Finland (83), Russia (1), Estonia (22), Latvia (16), Lithuania (18), Belorussia (28), Ukraine (59) and Moldova (27). In Year 2002 was initiated another large coverage project - European Position Determination System "EUPOS®". Currently there are about 400 continuously operating GNSS (Global Navigation Satellite Systems) stations covering EU countries Estonia, Latvia, Lithuania, Poland, Czech Republic, Slovakia, Hungary, Bulgaria, Romania and East European countries Ukraine and Moldavia. EUPOS® network is a ground based GNSS augmentation system widely used for geodesy, land surveying, geophysics and navigation. It gives the opportunity for fast and accurate position determination never available before. It is an honorable task to use the EUPOS® system for research of the Struve triangulation former sites. Projects with Struve arc can popularize geodesy, geo-information and its meaning in nowadays GIS and GNSS systems. Struve Arc and its points is unique cooperation cross-border object which deserve special attention because of their natural beauty and historical value for mankind. GNSS in geodesy discovers a powerful tool for the verification and validation of the height values of geodetic leveling benchmarks established historically almost 200 years ago. The differential GNSS and RTK methods appear very useful to identify vertical displacement of landscape by means of
Optimization Model for Headway of a Suburban Bus Route
Directory of Open Access Journals (Sweden)
Xiaohong Jiang
2014-01-01
Full Text Available Due to relatively low passenger demand, headways of suburban bus route are usually longer than those of urban bus route. Actually it is also difficult to balance the benefits between passengers and operators, subject to the service standards from the government. Hence the headway of a suburban bus route is usually determined on the empirical experience of transport planners. To cope with this problem, this paper proposes an optimization model for designing the headways of suburban bus routes by minimizing the operating and user costs. The user costs take into account both the waiting time cost and the crowding cost. The feasibility and validity of the proposed model are shown by applying it to the Route 206 in Jiangning district, Nanjing city of China. Weightages of passengers’ cost and operating cost are further discussed, considering different passenger flows. It is found that the headway and objective function are affected by the weightages largely.
Papp, Dávid
2013-01-01
We propose a novel optimization model for volumetric modulated arc therapy (VMAT) planning that directly optimizes deliverable leaf trajectories in the treatment plan optimization problem, and eliminates the need for a separate arc-sequencing step. In this model, a 360-degree arc is divided into a given number of arc segments in which the leaves move unidirectionally. This facilitates an algorithm that determines the optimal piecewise linear leaf trajectories for each arc segment, which are deliverable in a given treatment time. Multi-leaf collimator (MLC) constraints, including maximum leaf speed and interdigitation, are accounted for explicitly. The algorithm is customized to allow for VMAT delivery using constant gantry speed and dose rate, however, the algorithm generalizes to variable gantry speed if beneficial. We demonstrate the method for three different tumor sites: a head-and-neck case, a prostate case, and a paraspinal case. For that purpose, we first obtain a reference plan for intensity modulated...
Making Conductive Polymers By Arc Tracking
Daech, Alfred F.
1992-01-01
Experimental technique for fabrication of electrically conductive polymeric filaments based on arc tracking, in which electrical arc creates conductive carbon track in material that initially was insulator. Electrically conductive polymeric structures made by arc tracking aligned along wire on which formed. Alignment particularly suited to high conductivity and desirable in materials intended for testing as candidate superconductors.