Browsing by Author "Niwunhella, D.H.H."

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Cost minimization model through consolidation: application to a third party logistics distribution center
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Weerakkody, H.D.W.; Niwunhella, D.H.H.; Wijayanayake, A.
Third Party Logistics (3PL) providing industry has become an essential service for the manufacturers due to the numerous benefits they could obtain by outsourcing their logistics activities to a 3PL provider. When considering the 3PL industry in Sri Lanka, growth can be seen in the past few decades. Since the distribution of goods of multiple clients in a 3PL Distribution Center (DC), is handled by the 3PL providers, they are much interested in minimizing the distribution cost which will not only ultimately benefit to the 3PL provider but also the client as well. However, managing the distribution of multiple clients at the same time with an optimized cost is challenging for 3PL service providers. The consolidation of goods of multiple clients in the distribution process is one of the main cost-effective strategies that the 3PLs could use. But due to several reasons such as compatibility constraint of goods transported, client concerns, complicated scheduling, consolidation is not practiced by many of the 3PLs in Sri Lanka. Therefore, this study was conducted on identifying the main factors to be considered when consolidating goods of multiple clients, and to develop a mathematical model to minimize the distribution cost in a 3PL DC by shipment consolidation. This paper proposes a mathematical model considering the Vehicle Routing Problem (VRP) as an extension found in the literature, where the compatibility of the products distributed has been added as a new constraint. The mathematical model has been tested and validated using the actual data obtained from few of the 3PL firms in Sri Lanka and has been simulated using the Supply Chain Guru Software. Different scenarios are created in the software to check the feasibility and accuracy of the model. The results obtained showcase an average cost reduction of nearly 25% when consolidating shipments of multiple clients in a 3PL DC. Therefore, it is evident from the study that, the 3PL firms could obtain a significant cost reduction by consolidating shipments of multiple clients. It was also identified that factors like compatibility of the distributed goods, cargo tonnage, clients’ privacy concerns and scheduling of shipments should be considered when consolidating goods of multiple clients to distribute in a 3PL DC. The findings of this research will help the 3PL providers to consider consolidating shipments of several clients and the mathematical model proposed in the research will help them to minimize the distribution cost. Furthermore, the trucks can be properly utilized, the number of trucks and fuel wastage can be reduced and the impact on the environment will be lesser. Future researches could be done on adding more complexity to the model by considering different constraints such as time windows for the orders.
Developing a methodology for evaluating the sustainability performance of logistics service providers using AHP
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Prabodhika, A.P.K.J.; Niwunhella, D.H.H.; Wijayanayake, A.
Sustainability and sustainable development have become a buzzing topic in today's business world. Business organizations are now more towards making themselves more economically, socially, and environmentally sustainable. With the introduction of concepts like “Sustainable Supply Chain Management” organizations have determined not only to make themselves sustainable but also to make the whole supply chain sustainable as well. Many manufacturers and retailers often outsource their logistics functions to Logistics Service Providers (LSPs) to focus more on their core business process. Due to the competitiveness and the popularity of the sustainability concept, those organizations evaluate their prospective LSPs not only based on economic aspects like cost, service quality but also on social and environmental aspects as well. This paper proposes a methodology for evaluating the sustainability performance of LSPs using the Analytical Hierarchy Process (AHP). A Composite Sustainability Performance Index (CSPI) was developed using AHP since multiple dimensions and indicators need to be incorporated when measuring the sustainability performance and composites indices assist in aggregating all dimensions and indicators into a single measurement which will be easy to interpret, compare and benchmark. CSPI can be used by organizations when selecting the LSPs as their business partners based on the performance of three traditional dimensions of sustainability; Economic, Social, and Environmental, and a newly included technological aspect. The proposed methodology is flexible as it depends on the sustainability requirements of a particular organization when selecting LSPs as the relative importance of the dimensions and its indicators are up to the organization to decide. Analytic Hierarchy Process (AHP) has been used to create a model and give relative importance for each dimension/indicator and then the sub-dimensions or sub-indicators under each dimension are compared. Weighted and evaluated indicators are then aggregated using linear additive aggregation to construct the CSPI based on which the LSPs can be evaluated. This proposed model enables the selection of the best LSP according to the organization's preference or requirements. The proposed methodology was then used to compare and select the 3 prospective LSPs of an apparel manufacturing organization using the data obtained through interviews and questionnaires. According to the results, the highest importance of the organization was given to the economic dimension (0.5498), then to environmental (0.2748), then social (0.1202), and least to the technology dimension (0.0554) by the decision-makers. CSPI values are computed as 3.6863, 3.1644, 3.3044 for LSP 1, LSP 2, LSP 3, respectively. Among them, the highest values were obtained by LSP 1 which is 3.6863 and it is the best selection among the three alternatives. The reason LSP 1 got the highest CSPI is, it has performed best in the highly weighted sustainability performance indicators by the organization when compared to the other two LPSs.
Developing a model for effective supplier selection using Analytic Network Process (ANP)
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Udakanjalee, H.I.; Niwunhella, D.H.H.; Wijayanayake, A.
If any organization needs to survive in this intensively competitive market, they should possess a competitive advantage over other companies. An effective supplier selection process is a major determinant of the degree of competitive advantage within an organization. The common drawbacks in the existing supplier selection processes which hinder the selection of effective supplier/suppliers are the absence of a systematic mechanism and subjectivity of decisions. It is also a disadvantage from suppliers’ perspective, as a supplier cannot systematically align their processes because requirements and expectations differ from organization to organization. Therefore, the objective of this research is to propose a mechanism and a general model to prioritize criteria, sub criteria, and alternative suppliers along with appropriate set of criteria and sub criteria and to validate it across few industries. With the scope of this paper, supplier selection was considered as a multi criteria decision making problem (MCDM) because supplier selection is the evaluation of trade-offs between inconsistent, contradictory and competing criteria with each other. Analytic Network Process (ANP) which is a technique to solve MCDM problems in which the criteria affect each other and have nonlinear correlation, is used here to prioritize criteria and alternatives. In this study, a systematic review of literature was conducted to identify the different research approaches, limitations, and gaps and to determine most appropriate criteria, sub-criteria, tools and techniques used for supplier selection. Then developed the tentative criteria list and tentative ANP model using data gathered through literature review. Then this model and criteria list was finalized through a survey in a chemical manufacturing company, by acquiring industry experts’ opinion. After finalizing the model, it is validated by feeding data obtained through past supplier selection records into it. Here results were compared and constructed with the actual results in each case. The results of the survey show that most important criteria that should consider when selecting suppliers for the selected product in this chemical manufacturing company are the production capability, delivery capability, financial capability and service capability of the supplier. In the current supplier selection process in this company, they consider only factors like the quality and price of product and punctuality delivery goods by suppliers. But these limited set of criteria have led to choosing ineffective suppliers. The result of this study shows the scope and the importance of criteria and sub criteria that should be used for supplier selection in this company. Here when comparing these results with past literature, it can be concluded that industry wise prioritizations are not exactly similar but can relate to general model with few modifications and assumptions. Also, when comparing the finalized model and mechanism with past literature it can be concluded that this model is more appropriate for large scale manufacturing companies who are mainly focusing on exports, procuring products than services, procuring products use as the raw materials in manufacturing processes.
Developing a Multi Criteria Decision Making Framework to Select the Most Suitable Production Line in Apparel Firms: Use of ANP Method
(IEOM Society International, 2021) Thalagahage, N.T.H; Wijayanayake, A.W.; Niwunhella, D.H.H.
The apparel industry is considered as one of the most labor-intensive industries where production planning and Control (PPC) is considered as an impoftant function, because of its involvement from scheduling each task i-n the process till the delivery of customer demand. Line planning is a sub process within PPC, through which the production orders are allocated to production lines according to its setting and due dates ofproduction completion. The decisions that address line planning function still heavily rely on the expertise of the ploduction planner. When production planners are required to select production lines for the production ofa particuiar type ofpioduct, little emphasis has been placed on ways to apportion ceftain production orders to the most appropriate pioduction system. In thii research, a framework is developed using Analyical Network Process (ANP) which is a Multi Critlria Decision Making (MCDM) method, enabling the incorporation of all the planning criteria in the selection of a production line. The weighted scores obtained by the best alternative production lines are used in a Linear Programming model to optimize the resource allocation in an apparel firm.
Effective Supplier Selection Using ANP
(IEOM Society International, 2021) udakanjaree, H.I.; wijayanayake, A.N.; Niwunhella, D.H.H.
A supplier provides monetary benefts as well as non-monetary benefits for the organization, especially to maintain company reputation and customer satisfaction. Therefore, an effective supplier netiork is an importani key success factor of the organization' There arT{n?ny c_ommon drawbacks in the existing supplier selection processes which hinder the selection ofeffective supplidr/suppliers. Therefore, the objective ofthis research is to develop a model and a mechanism to overcome these common drawbacks while predicting ttre validity of the model across a few industries. With the scope of this paper, supplier selection was considered as a multi-criteria decision making problem 1UCOUI because supplier selection is the evaluation of trade-offs between multiple criteria. Analytic Network process (AI.tp) which is a technique to solve MCDM problems in which the criteria aff:ect each other ani have nonlinear correiatiorl is used here to prioritize criteria and alternatives. Therefore, this model is flexible for selecting suppliers for any product/service across any organization, sector, and industry. The significance of the proposed mo-clel is'its Flexibility across any industry with limitations and supports multiple criteria wlth any number of aliernatives.
Framework to select the most suitable production line in an apparel firm in Sri Lanka: use of Analytical Hierarchical Process
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Thalagahage, N.T.H.; Niwunhella, D.H.H.; Wijayanayake, A.
The apparel industry is considered as one of the most labour-intensive industries in the world despite the technological advancements and the amount of automation. Line planning in the garment industry is the process of scheduling and allocating production orders to production lines according to the product setting and due dates of manufacturing completion. Most of the apparel manufacturers in Sri Lanka have switched to lean model production, in which large sewing departments are split into smaller, self-balancing sewing lines. The decisions that address the production line selection process for a particular production order still heavily rely on production planners, based on their experience. These decisions tend to be neither consistent nor scientific because of the lack of interdepartmental connectivity. Little emphasis has been placed on the impact of the planning considerations and ways to apportion certain production orders to the appropriate production system with specific characteristics. This problem is addressed in the research through the development of a multi criteria decision making framework to enable the incorporation of all the parameters to select the best production line for a particular sales order using Analytical Hierarchical Process (AHP). AHP method is adopted for decision making which models multiple, possibly conflicting factors dependent on each other and it makes appropriate trade-offs to recommend well-balanced solutions to different stakeholders. The production line selection criteria identified through expert opinions and literature review were applied in the AHP conceptual model. 23 factors were identified and they were categorized under 5 areas which are characteristics of the product, characteristics of the production order, characteristics of the production line, technical support and quality parameters. In order to build the AHP model, 4 manufacturing firms and 4 senior and middle level managerial industrial experts from each firm were selected and interviewed through AHP questionnaires. After the pairwise comparisons, each criterion was weighted and prioritized. Most of the interviews resulted in high priority for delivery date, technical infrastructure, skills inventory of the line, the efficiency of the line, and cadre requirement while the ability to adopt changeovers, prioritization of machine service, and infrastructure support by the technicians were given low priorities. This interprets that, for any kind of a production order the mostly prioritized criteria are important to be considered. Therefore, focusing on them in line selection would lead to improved planning efficiency. After the criteria comparison, each alternative production line was given a score against the planning criteria and the production lines were ranked in order to select the best production line. Through data analysis, it was found out that the results obtained from different industrial experts representing different apparel manufacturing firms vary from each other depending on individual perspective and policies inherent to the manufacturing firm. However, the framework can relate to any apparel manufacturing firm by allowing Decision Makers to select the valid criteria depending on the Production Order and its related parameters. Also, the framework can be used for other manufacturing industries with few modifications and assumptions. In order to avoid the subjectivity in AHP method, a Linear Programming model can be developed as a future improvement and optimize the production lines selected through AHP ranking.
Measuring Sustainability Performance of Logistics Service Providers using AHP
(IEOM Society International, 2021) Prabodhika, A.P.K.J.; Wijayanayake, A.; Niwunhella, D.H.H.
Many manufacturers and retailers often outsource their logistics functions to Logistics Service Providers (LSPs) to focus more on their core business process. Due to the competitiveness and the popularity of the sustainability concept, those organizations evaluate their prospective LSPs not only based on economic aspects like cost, service quality but also on social and environmental aspects as well. This paper proposes a model that can be used by organizations when evaluating and selecting LSPs based on their sustainability performance. Along with the traditional three dimensions of sustainability, a new dimension of Information Technology (IT) is incorporated into the model. A Composite Sustainability Performance Index (CSPI) is constructed using the Analytical Hierarchy Process (AHP) as a weighting method and linear aggregation method since multiple dimensions and indicators need to be incorporated when measuring sustainability performance. The proposed model is flexible as it depends on the sustainability requirements of the organization when selecting LSPs and their relative impoftance of the sustainability dimensions and indicators are up to the organization to decide. The proposed model is applied to an apparel manufacturing organization to evaluate and select their prospective LSPs.
A Review on City Logistics and Two Echelon Freight Modelling
(International Conference on Industrial Engineering and Operations Management, 2020) Warnakulasuriya, M.M.; Niwunhella, D.H.H.; Nanayakkara, L.D.J.F.; Wickramarachchi, Ruwan
When cities are growing in both size and complexity, the freight distribution and management make a significant challenge for transportation management. Freight transportation execution is one of the main sectors that is looked into when planning. The concept of city logistics explicitly tries to optimize the urban transport network and many optimization approaches have been introduced to optimize the vehicle routing methods considering several objectives. Since recent times, there is drawing attention for two-echelon freight consolidation modelling efforts with the emerging of megacities. This paper reviews the available literature under the city logistics modelling, and two-echelon freight consolidation for identifying the perspectives adhered. The study was conducted through a systematic review of literature using multiple studies published under the area of city logistic modeling and two-echelon-distribution modelling in thorough key word base search of city logistic modelling efforts, and performance parameters used for freight analysis within city networks from the findings. The review framework takes into account the diversity and complexity found in city logistics practices. It was evident that there is a lack of modelling efforts in two-echelon vehicle routing for city logistic combining with optimization models for dealing with multiple objective and modeling uncertainty.
Vehicle Routing and Shipment Consolidation in a 3PL DC: A Systematic Literature Review of the Solution Approaches
(IEOM Society International, 2021) Weerakkody, H.D.W.; Wijayanayake, A.; Niwunhella, D.H.H.
Many of the manufacturing companies tend to outsource their logistic activities to third party logistics (3PL) providers due to numerous benefits they could obtain. Since 3PL providers provide their distribution services for multiple clients at the same time, managing these activities properly with an optimized cost is challenging for them, So, they are much interested in minimizing the distribution cost which will ultimately benefit the 3PL provider, and thereby the client as well. Shipment consolidation is one of the best and effective cost reduction strategies which could be followed by the 3PL firms, when distributing goods of multiple clients. Vehicle Routing Problem (VRP) which is a well-discussed problem in the literature can be applied here since it is beneficial for the 3PL providers to find the optimal routes to distribute the goods from the central 3PL Distribution Center (DC), while consolidating shipments of multiple clients. Therefore, this literature survey has been carried out to analyze the solution approaches, used in the literature related to VRP and shipment consolidation such that it would help in future research in developing a model to optimize the distribution in a 3PL DC by consolidating shipments of multiple clients. The results of the study have shown that most of the referred papers have used metaheuristic algorithms in solving their models and when the number of nodes are larger, it is suitable to use metaheuristic algorithms. Therefore, it can be concluded that a metaheuristic algorithm would be appropriate when developing a model to optimize the distribution in a 3PL DC by consolidating shipments of multiple clients.