Wasantha Daundasekera

University of Peradeniya | UOP · Department of Mathematics

This study proposed a metaheuristic algorithm known as the Ant Colony Optimization Algorithm (ACOA) to solve the deterministic Assignment Problem (AP) with a single objective. The AP is a special type of linear programming problem where the objective is to minimize the cost or time of completing a number of jobs by a number of persons/machines. The...

The vehicle routing and vehicle scheduling problems are two of the well-studied problems in the field of Operations Research. Most of the operations in these two problems are interrelated at a collection center in a supply chain. Therefore, the proper coordination among these interrelated operations is essential to increase the efficiency of the su...

In a warehouse with a single-door, the scheduling is only a matter of sequencing the vehicles to that door. This study focuses on the scheduling vehicles to a warehouse with multi-doors. Therefore, not only sequencing but also assigning vehicles to the doors are taken into consideration. The proper scheduling the vehicles to the doors at a warehous...

In this study, one of the internal operations at the Cross-docking Terminal (CDT), moving shipments (MS) from receiving doors to shipping doors of CDT is integrated with Open Vehicle Routing Problem (OVRP) and the problem is indicated here as OVRPCD-MS. As an additional feature, asymmetric distance between any two customers is assigned by incorpora...

The efficiency of a supply chain can be improved by integrating certain inter-related transportation problems and combining a few operations at a logistics center with routing the vehicles. This study is an extended work on a Mixed Integer Quadratic Programming (MIQP) model developed to solve the integrated Vehicle Routing and Scheduling Problem (V...

The cross-docking is an innovative logistic technique in a supply chain. A cross-docking center not only collects shipments from the suppliers, but also dispatches them to the customers. In a previous study, some internal operations at this center were integrated to develop a model for the Vehicle Routing Problem with Moving Shipments at the Cross-...

Cross-Docking (CD) is a modern distribution strategy in a supply chain. The optimal scheduling of vehicle routing, known as the Vehicle Routing Problem (VRP), is one of the influential factors of the efficiency of a supply chain. In recent years, researchers and business consultants in different organizations have been interested in integrating the...

To have an efficient Supply Chain (SC), the coordination and integration of the activities in the SC are mandatory. Routing vehicles is an optimization problem in the SC. When the routed vehicles return to the depot and the doors at the depot are busy, the returned vehicles must wait to unload the accumulated shipments. Therefore, properly scheduli...

This study intends to amalgamate the Vehicle Routing Problem (VRP) and Vehicle Assignment Problem (VAP). Therefore, the objective of this study is to propose a Genetic Algorithm (GA) to reach a near-optimal solution to the integrated Vehicle Routing and Assigning Problem (VR&AP) with a multi-stack door pre-distribution centre. In the ‘routing proce...

The efficiency of a supply chain (SC) is crucial for survival in the globalized industrial environment. Industries adopt the innovative logistic strategy known as “Cross-docking” in their SC to satisfy the requirements of customers in terms of time, quality, and cost. A cross-docking system (CDS) operates as a transshipment center between suppliers...

The goal of an efficient supply chain (SC) is to supply or deliver the shipments to the right place in the right quantity at the right time with a low cost. To be an efficient SC, the coordination and integration of the activities in the SC are mandatory. Routing vehicles to collect the shipments from the suppliers with minimum travelling cost is a...

Cross-docking (CD), a relatively new technique, is considered an efficient technique to control the inventory flow in logistics. CD can reduce delivery lead times, inventory holding, and transportation costs. This research extends the study on vehicle routing problem with moving shipments at the cross-docking center (VRPCD&MS). The objectives of th...

In the literature amathematical model had been presented to transport a homogeneous product from multi-source to multi-destination, to meet the demand of each destination at a time. Both the demand and the supply were assumed to vary within a certain range. The total cost bounds of transportation were obtained by using the LINGO solver. Here we emp...

Vehicle Routing Problem (VRP) is a well-known combinatorial optimization problem. In the case of single-door at the depot to enter, vehicles have to wait in the parking yard until they get their turn to unload their accumulated products. This waiting creates additional transportation cost and therefore, this idle time of each vehicle in the parking...

Cross-Docking (CD) technique was initiated in the 1930s to make a cost-effective supply chain. Vehicle Routing Problem (VRP) is one of the widely discussed optimization problems. The research on integration of VRP with CD (VRPCD) was initiated at the beginning of 2000s. Moving Shipments (MS) from receiving doors to shipping doors is an activity ins...

Since the Vehicle Routing Problem (VRP) is proven NP-hard, particularly for large-scale problems, metaheuristic methods are essential to solve and reach near-optimal solutions. The Genetic Algorithm (GA) is considered a suitable metaheuristic method to solve such problems in which some parameters have to be configured at the beginning of the Algori...

In the population based meta-heuristic methods, initial solution plays a significant role to reach a near optimal solution in a reasonable computational time. Initial solution is usually generated randomly but it consumes more time to reach the optimal solution. Greedy approach is a better way than the results obtain through randomly generated...

Presented at the iOURS2022

Cross-docking (CD) technique was initiated in 1930s to make supply chain cost effective. However, from 1980s, after the successful application of this technique to Walmart food chain industry, it became popular among manufacturing and retailing companies. Vehicle routing problem (VRP) is one of the widely discussed optimization problems. The resear...

Vehicle Routing Problem (VRP) plays a vital role in supply chain (SC) management. The cross-docking (CD) strategy was introduced in the 1930s to reduce up to 70% of warehousing at traditional distribution centres in SCs. The research on integrating VRP with CD (VRPCD) was initiated in 2006. Open VRP (OVRP) is one of the variants of VRP, and it is m...

Presented at the RESCON2022

Optimization processes in mathematics, computer science, and economics solve problems effectively by selecting the best element from a set of available alternatives. One of the most important and successful applications of optimization is the transportation problem (TP), which is a subclass of linear programming (LP) in operations research (OR). It...

An innovative and creative docking technique known as cross-docking (CD) strategy was initiated in 1930s to make supply chain fast and productive. However, it only became popular from 1980s. Vehicle routing between suppliers/customers to CD terminal (CDT) is one of operational level problems at CDT. Moreover, moving unloaded products from indoors t...

The maximum flow problem is also one of the highly regarded problems in the field of optimization theory in which the objective is to find a feasible flow through a flow network that obtains the maximum possible flow rate from source to sink. The literature demonstrates that different techniques have been developed in the past to handle the maximum...

A unified explicit form for difference formulas to approximate the fractional and classical derivatives is presented. The formula gives finite difference approximations for any classical derivatives with a desired order of accuracy at nodal point in the computational domain. It also gives Gr\"unwald type approximations for fractional derivatives wi...

The Transportation problem is one of the most colorful and demanding problems in the history of Operations Research. Many researchers have paid attention to solve the problem using different approaches. In certain approaches focused on finding an initial basic feasible solution and the other to find the optimal solution. It can be noticed that th...

The Capacitated Vehicle Routing Problem (CVRP) is a special variant of the Vehicle Routing Problem which has been extensively addressed in the literature of Operations Research. Since CVRP is a NP-hard problem, only heuristic algorithms are capable of solving relatively large-scale problems. In this research paper, a new Improved Two-phased Heurist...

Identifying a combination of variables causing infections or infectious diseases is one of the main tasks in clinical models in medicine. Logistic Regression (LR) has been widely used to identify such variable under the assumptions of linearity of independent variables and absence of multi-collinearity. Experimental data which has a large number of...

The Capacitated Vehicle Routing Problem (CVRP) is a special variant of the Vehicle Routing Problem (VRP) which is extensively addressed in the literature because of its vast applicability. Since the problem is NP-hard, only heuristic algorithms are capable to find satisfactory approximate solutions for relatively large problems within a reasonable...

Transportation of products from sources to destinations with minimal total cost plays a key role in logistics and supply chain management. The transportation problem (TP) is an extraordinary sort of Linear Programming problem where the objective is to minimize the total cost of disseminating resources from several various sources to several destina...

The Capacitated Vehicle Routing Problem (CVRP) is a special variant of the vehicle routing problem which has been extensively addressed in the literature. Because of the NP-Hardness, excessive time is required to find the exact solution to CVRP. Therefore, meta-heuristics are generally applied to solve this type of problems. Among the popular meta-...

An explicit form for coefficients of shifted Grünwald type approximations of fractional derivatives is presented. This form directly gives approximations for any order of accuracy with any desired shift leading to efficient and automatic computations of the coefficients. To achieve this, we consider generating functions in the form of power of a po...

A general explicit form for generating functions for approximating fractional derivatives is derived. To achieve this, an equivalent characterisation for consistency and order of approximations established on a general generating function is used to form a linear system of equations with Vandermonde matrix for the coefficients of the generating fun...

This paper presents a real time nonlinear quadratic programming model to minimize the aggregate delay time of vehicles at each intersection by minimizing the total number of vehicles at each intersection at the signalized two intersections arterial. This can be extended to more than two intersections arterial network by expanding the groups which i...

This paper presents a real time nonlinear quadratic programming model to minimize the aggregate delay time of vehicles at each intersection by minimizing the total number of vehicles at each intersection at the signalized two intersections arterial. This can be extended to more than two intersections arterial network by expanding the groups which i...

This paper presents a real time non-linear quadratic programming model to minimize the aggregate delay time of vehicles at each lane by minimizing number of vehicles at each lane at the signalized intersection. One of the most important efficiency and easily getting factors of traffic signal control is the number of vehicles in a queue at the signa...

This paper presents a real time non-linear quadratic programming model to minimize the aggregate delay time of vehicles at each lane by minimizing number of vehicles at each lane at the signalized intersection. One of the most important efficiency and easily getting factors of traffic signal control is the number of vehicles in a queue at the signa...

Energy problem is undoubtedly one of the most serious global problems people all over the world are facing today. Energy resources, especially fossil fuels, are crucial to everyone on the earth. Unfortunately, these resources are nonrenewable. Besides, great consumption of fossil fuels is also causing severe environmental problems. Therefore, impro...

Sawmilling is a primary industry which provides raw materials to other industries such as construction, joinery, furniture and others. The raw material used in sawmills consists of logs which come from different forests. Logs are classified by diameter, length and quality. Depending on the consumer demand for the products and the nature of the prod...

Increasing cost of raw material and need to avoid industrial wastage, solving cutting stock problems became of great interest in the area of Operations Research. An optimum cutting stock problem can be defined as cutting a main sheet into smaller pieces while minimizing total wastage of the raw material or maximizing overall profit obtained by cutt...

In this report we discuss an application to the shortest path problem. In our application we consider the road network connecting district capitals in Sri Lanka. Only class A&B roads are considered in this report. Our objective is to find the shortest route with respect to the distance from the origin to the destination while visiting other selecte...