scholarly journals Efficient Solution Approach to Maximum Flow Evacuation Planning Problem without Flow Conservation Aspect

2018 ◽  
Vol 13 (1) ◽  
pp. 108-116
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka
Keyword(s):  
Network Flow ◽  
Efficient Solution ◽  
Maximum Flow ◽  
Evacuation Planning ◽  
Planning Problem ◽  
Intermediate Node ◽  
Solution Approach ◽  
Solution Strategies ◽  
Source Sink ◽  
Flow Conservation

 An attempt of shifting as more people as possible and/or their logistics from a dangerous place to a safer place is an evacuation planning problem. Such problems modeled on network have been extensively studied and the various efficient solution procedures have been established. The solution strategies for these problems are based on source-sink path augmentation and the flow function satisfies the flow conservation at each intermediate node. Besides this, the network flow problem in which flow may not be conserved at node necessarily could also be used to model the evacuation planning problem. This paper proposes a model for maximum flow evacuation planning problem on a single-source-single-sink static network with integral arc capacities with holding capability of evacuees in the temporary shelter at intermediate nodes and extends the model into the dynamic case. Journal of the Institute of Engineering, 2017, 13(1): 108-116

scholarly journals Non-conserving Flow Aspect of Maximum Dynamic Flow Problem

2018 ◽  
Vol 14 (1) ◽  
pp. 107-114
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka
Keyword(s):  
Network Flow ◽  
Efficient Solution ◽  
Flow Problem ◽  
Dynamic Network ◽  
Maximum Flow ◽  
Solution Procedure ◽  
Evacuation Planning ◽  
Planning Problem ◽  
Intermediate Node ◽  
Flow Conservation

Shifting as many people as possible from disastrous area to safer area in a minimum time period in an efficient way is an evacuation planning problem (EPP). Modeling the evacuation scenarios reflecting the real world characteristics and investigation of an efficient solution to them have become a crucial due to rapidly increasing number of natural as well as human created disasters. EPPs modeled on network have been extensively studied and the various efficient solution procedures have been established where the flow function satisfies the flow conservation at each intermediate node. Besides this, the network flow problem in which flow may not be conserved at nodes necessarily could also be useful to model the evacuation planning problem. This paper proposes an efficient solution procedure for maximum flow evacuation planning problem of later kind on a single-source-single-sink dynamic network with integral arc capacities with holding capability of flow (evacuees) in the temporary shelter at intermediate nodes. Journal of the Institute of Engineering, 2018, 14(1): 107-114

scholarly journals Flow Improvement in Evacuation Planning with Budget Constrained Switching Costs

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Ram Chandra Dhungana ◽  
Tanka Nath Dhamala
Keyword(s):  
Network Flow ◽  
Large Scale ◽  
Maximum Flow ◽  
Evacuation Planning ◽  
Solution Technique ◽  
Planning Problem ◽  
Constrained Problems ◽  
Full Capacity ◽  
Evacuation Plan ◽  
Flow Improvement

Many large-scale natural and human-created disasters have drawn the attention of researchers towards the solutions of evacuation planning problems and their applications. The main focus of these solution strategies is to protect the life, property, and their surroundings during the disasters. With limited resources, it is not an easy task to develop a universally accepted model to handle such issues. Among them, the budget-constrained network flow improvement approach plays significant role to evacuate the maximum number of people within the given time horizon. In this paper, we consider an evacuation planning problem that aims to shift a maximum number of evacuees from a danger area to a safe zone in limited time under the budget constraints for network modification. Different flow improvement strategies with respect to fixed switching cost will be investigated, namely, integral, rational, and either to increase the full capacity of an arc or not at all. A solution technique on static network is extended to the dynamic one. Moreover, we introduce the static and dynamic maximum flow problems with lane reversal strategy and also propose efficient algorithms for their solutions. Here, the contraflow approach reverses the direction of arcs with respect to the lane reversal costs to increase the flow value. As an implementation of an evacuation plan may demand a large cost, the solutions proposed here with budget constrained problems play important role in practice.

scholarly journals Model and Solution for Non-conservation Flow Evacuation Planning Problem

2019 ◽  
Vol 36 (1-2) ◽  
pp. 11-16
Author(s):  
Shree Ram Khadka ◽  
Phanindra Prasad Bhandari
Keyword(s):  
Efficient Solution ◽  
Solution Procedure ◽  
Optimization Models ◽  
Evacuation Planning ◽  
Planning Problem ◽  
Safe Place ◽  
Response Phase ◽  
Evacuation Plan ◽  
Flow Conservation ◽  
Important Notion

Efficient evacuation plan with which a maximum evacuees can be sent as soon as possible from the disastrous place to the safe place is an important notion during the response phase of the disaster management. Such a plan in terms of optimization models has been extensively studied in a various scenarios, see [3]. The optimization models have been based on the flow conservation constraint which permits an evacuee to be taken out of the disastrous place only if it can be sent into the safe place. However, the evacuation plan model with no flow conservation can keep several evacuees in the relatively safe places besides the evacuees which could be sent into the safe place. In this paper, we describe an optimization model for the evacuation plan based on the non-conservation flow constraint with an efficient solution procedure which keeps a maximum evacuees on the prioritized intermediate places besides a maximum evacuees into the specified safe place.

scholarly journals Maximum Flow Evacuation Planning Problem with Non-Conservation Flow Constraint

2020 ◽  
Vol 10 (1) ◽  
pp. 25-32
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka
Keyword(s):  
Optimization Model ◽  
Efficient Algorithm ◽  
Time Horizon ◽  
Maximum Flow ◽  
Safe Zone ◽  
Evacuation Planning ◽  
Planning Problem ◽  
Flow Conservation

The optimization model of the maximum flow evacuation planning problem efficiently sends a maximum number of evacuees along with the routes of their transshipment from the disastrous zone, the source, to the safe zone, the sink, over a given time horizon. The limitation of the problem with the flow conservation constraint at the intermediate nodes is that even one more evacuee cannot be sent out from the source, if the evacuee cannot reach the sink. However, evacuators must attempt to send out as many evacuees as possible to safer places despite the sink. There may be relatively safe places in between the source and the sink. The limitation is due to the flow conservation constraint. In this paper, we remodel the problem with non-conservation flow constraint and propose an efficient algorithm. With this approach one can send as many evacuees as in the flow conservation case from the source to the sink. Moreover, a maximum number of evacuees can also be sent to the relatively safe places in between the source and the sink. The routes of their transshipment can also be identified.

scholarly journals A survey on network contraflow evacuation planningproblems

2015 ◽  
Vol 3 ◽  
pp. 44-53
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka
Keyword(s):  
Network Flow ◽  
Dynamic Network ◽  
Route Planning ◽  
Evacuation Planning ◽  
Solution Strategies ◽  
General Network ◽  
Evacuation Route Planning ◽  
Network Flow Optimization ◽  
Evacuation Route ◽  
Potential Remedy

Evacuation planning is becoming crucial due to an increasing number of natural and human-created disasters over last few decades. One of the efficient ways to model the evacuation situation is a network flow optimization model. This model captures most of the necessities of the evacuation planning. Moreover, dynamic network contraflow modeling is considered a potential remedy to decrease the congestion due to its direction reversal property and it addresses the challenges of evacuation route planning. However, there do not exist satisfactory analytical results to this model for general network. In this paper, it is tried to provide an annotated overview on dynamic network contraflow problems related to evacuation planning and to incorporate models and solution strategies to them developed in this field to date.

scholarly journals A Simple Algorithm for Finding Maximal Network Flows and an Application to the Hitchcock Problem

1957 ◽  
Vol 9 ◽  
pp. 210-218 ◽  
Author(s):  
L. R. Ford ◽  
D. R. Fulkerson
Keyword(s):  
Network Flow ◽  
Network Flows ◽  
Simple Algorithm ◽  
Rand Corporation ◽  
Network Flow Problem ◽  
Intermediate Node ◽  
Flow Capacity ◽  
Source To Sink ◽  
Image Position ◽  
Source Sink

The network-flow problem, originally posed by T. Harris of the Rand Corporation, has been discussed from various viewpoints in (1; 2; 7; 16). The problem arises naturally in the study of transportation networks; it may be stated in the following way. One is given a network of directed arcs and nodes with two distinguished nodes, called source and sink, respectively. All other nodes are called intermediate. Each directed arc in the network has associated with it a nonnegative integer, its flow capacity. Source arcs may be assumed to be directed away from the source, sink arcs into the sink. Subject to the conditions that the flow in an arc is in the direction of the arc and does not exceed its capacity, and that the total flow into any intermediate node is equal to the flow out of it, it is desired to find a maximal flow from source to sink in the network, i.e., a flow which maximizes the sum of the flows in source (or sink) arcs.Thus, if we let P1 be the source, Pn the sink, we are required to find xij (i,j =1, . . . , w) which maximize

scholarly journals Abstract Contraflow Models and Solution Procedures for Evacuation Planning

2018 ◽  
Vol 10 (4) ◽  
pp. 89
Author(s):  
Ram Chandra Dhungana ◽  
Urmila Pyakurel ◽  
Tanka Nath Dhamala
Keyword(s):  
Efficient Solution ◽  
Flow Model ◽  
Efficient Algorithms ◽  
Evacuation Planning ◽  
Flow Paths ◽  
Evacuation Time ◽  
Solution Approach ◽  
Switching Property ◽  
Risk Areas

The abstract flow model deals with the flow  paths (routes) that satisfy the switching property. Contraflow is a widely accepted solution approach that increases the flow and decreases the evacuation time making the traffic smooth during evacuation by reversing the required road directions from the risk areas to the safe places. In this paper, we integrate the concepts of abstract flow and contraflow, give mathematical formulations of these models and present efficient algorithms for solving the abstract contraflow problems. The efficient solution procedures are presented for  maximum dynamic, lexicographically maximum and earliest arrival abstract contraflow  problems. This approach maximizes the flow value in given time and seeks to eliminate the crossing conflicts.

scholarly journals On the Transit-Based Evacuation Strategies in an Integrated Network Topology

2020 ◽  
Vol 37 (1-2) ◽  
pp. 1-13
Author(s):  
Iswar Mani Adhikari ◽  
Tanka Nath Dhamala
Keyword(s):  
Network Topology ◽  
Network Flow ◽  
Dynamic Network ◽  
Evacuation Planning ◽  
Planning Problem ◽  
Integrated Network ◽  
Routing Problem ◽  
Flow Models ◽  
Dynamic Network Flow ◽  
Important Variant

Evacuation planning problem deals with sending the maximum number of evacuees from the danger zone to the safe zone in minimum time as eciently as possible. The dynamic network flow models for various evacuation network topology have been found suitable for the solution of such a problem. Bus based evacuation planning problem (BEPP), as an important variant of the vehicle routing problem (VRP), is one of the emerging evacuation planning problems. In this work, an organized overview of this problem with a focus on their solution status is compactly presented. Arrival patterns of the evacuees including their transshipments at different pickup locations and their assignments are presented. Finally, a BEPP model and a solution for a special network are also proposed.

scholarly journals Abstract Contraflow Models and Solution Procedures for Evacuation Planning

2018 ◽  
Vol 10 (4) ◽  
pp. 88 ◽  
Author(s):  
Ram Chandra Dhungana ◽  
Urmila Pyakurel ◽  
Tanka Nath Dhamala
Keyword(s):  
Efficient Solution ◽  
Flow Model ◽  
Efficient Algorithms ◽  
Evacuation Planning ◽  
Flow Paths ◽  
Evacuation Time ◽  
Solution Approach ◽  
Switching Property ◽  
Risk Areas

The abstract flow model deals with the flow  paths (routes) that satisfy the switching property. Contraflow is a widely accepted solution approach that increases the flow and decreases the evacuation time making the traffic smooth during evacuation by reversing the required road directions from the risk areas to the safe places. In this paper, we integrate the concepts of abstract flow and contraflow, give mathematical formulations of these models and present efficient algorithms for solving the abstract contraflow problems. The efficient solution procedures are presented for  maximum dynamic, lexicographically maximum and earliest arrival abstract contraflow  problems. This approach maximizes the flow value in given time and seeks to eliminate the crossing conflicts.

scholarly journals Lexicographically Maximum Contraflow Problem with Vertex Capacities

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka
Keyword(s):  
Road Network ◽  
Maximum Flow ◽  
Evacuation Planning ◽  
Planning Problem ◽  
Solution Algorithms ◽  
Computational Performance ◽  
Speed Up ◽  
Priority Order ◽  
Vertex Capacities ◽  
Direction Reversal

The contraflow approach has been extensively considered in the literature for modeling evacuations and has been claimed, due to its lane-direction-reversal capability, as an efficient idea to speed up the evacuation process. This paper considers the contraflow evacuation model on network with prioritized capacitated vertices that allows evacuees to be held at intermediate spots too, respecting their capacities and priority order. In particular, it studies the maximum flow evacuation planning problem and proposes polynomial and pseudo-polynomial time solution algorithms for static network and dynamic multinetwork, respectively. A real dataset of Kathmandu road network with evacuation spaces is considered to implement the algorithm designed for dynamic multinetwork and to observe its computational performance.

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