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

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

2018 ◽  
Vol 13 (1) ◽  
pp. 108-116
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka

 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


Author(s):  
Ram Uday Sah ◽  
Shree Ram Khadka

<p>Evacuation planning problem can be considered as a dynamic flow problem on the dynamic network. In a dangerous situation, as many individuals as possible should be rescued from a dangerous zone to a safety zone as quickly and efficiently as possible. The earliest arrival flow problem is to send a maximal amount of dynamic flow reaching the safety zone sink not only for the given time horizon, but also for any earlier moment of the time horizon. In this paper we discuss the optimization formulation of the earliest arrival evacuation planning problem with efficient solution procedure.</p><p><strong>Journal of Advanced College of Engineering and Management,</strong> Vol. 2, 2016, page: 57-62</p>


2019 ◽  
Vol 36 (1-2) ◽  
pp. 11-16
Author(s):  
Shree Ram Khadka ◽  
Phanindra Prasad Bhandari

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.


Author(s):  
Ram Chandra Dhungana ◽  
Tanka Nath Dhamala

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.


2020 ◽  
Vol 37 (1-2) ◽  
pp. 1-13
Author(s):  
Iswar Mani Adhikari ◽  
Tanka Nath Dhamala

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.


2020 ◽  
Vol 10 (1) ◽  
pp. 25-32
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka

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.


2015 ◽  
Vol 3 ◽  
pp. 44-53
Author(s):  
Phanindra Prasad Bhandari ◽  
Shree Ram Khadka

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.


1983 ◽  
Vol 92 (3) ◽  
pp. 171-190
Author(s):  
S N Narahari Pandit ◽  
B Krishna Reddy

Author(s):  
Omar Mutab Alsalami ◽  
Ali Muhammad Ali Rushdi

This paper presents a review of flow network concepts, including definition of some graph-theoretic basics and a discussion of network flow properties. It also provides an overview of some crucial algorithms used to solve the maximum-flow problem such as the Ford and Fulkerson algorithm (FFA), supplemented with alternative solutions, together with the essential terminology for this algorithm. Moreover, this paper explains the max-flow min-cut theorem in detail, analyzes the concepts behind it, and provides some examples and their solutions to demonstrate this theorem. As a bonus, it expounds the reduction and transformation techniques used in a capacitated network. In addition, this paper reviews one of the popular techniques for analyzing capacitated networks, which is the “decomposition technique”. This technique is centered on conditioning a complicated network on the possible states of a keystone element  or on the possible combinations of states of many keystone elements. Some applications of capacitated network problems are addressed based on each type of problem being discussed.


2017 ◽  
Vol 13 (5) ◽  
pp. 0-0 ◽  
Author(s):  
Hari Nandan Nath ◽  
◽  
Urmila Pyakurel ◽  
Tanka Nath Dhamala ◽  
Stephan Dempe ◽  
...  

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