Examples

The objective of the thesis is the investigation of practices aiming to measure the sustainability performance of beef and soy supply chains, and consequently the elaboration of a sustainability measurement tool which would support the decision making process. The thesis includes a desk research which gives an overview of the contemporary approaches and already existing tools for measuring and monitoring sustainability results in the supply chains. The desk research as well as the data provided from the SALSA project (a EU project at the chairgroup related to the sustainability of  soy and beef chains) is the basis for the elaboration of the Excel Tool. Four perspectives are taken into consideration: global warming, energy consumption, water consumption and costs (profit). The four components are constituted by various parameters. All stages of the soy and beef supply chains are measured and the results are represented numerically and graphically. The Excel Tool supports the development of three scenarios: basic, secondary and target. The results of the three scenarios are compared and evaluated. Finally, case studies are applied in order to test the validity of the Excel Tool.

Improving the efficiency of a supply chain with network design is being used in a variety of fields. MILP is one of the methods that is frequently applied to network design problems. This research specifically focuses on multiple hub locations with inventory and process allocation problem for the floricultural supply chain, a problem that originates from the DaVinc3i project (running at the chairgroup). The formulation of the model is based on MILP and aims to minimize total costs. A case study is included to prove the applicability of the formulation. The model is programmed in  Excel, using the Solver as well as an artificial analysis. The model needs to be able to find the optimal location of hubs with suitable process and inventory nodes in the floricultural supply chain. The optimal solution in the example case study is given, but in practice, the optimal plan is highly vulnerable to different situations and contexts, such as different transport costs and fixed costs. The scientific contribution of this research can be used in more complex floricultural hub allocation problems as a basic model; it also is applicable for other type of supply chains.

This research took place at the international retailer HEMA. The aim of the research was to find out how the order frequency can be increased, while the costs are minimized, to create a more responsive supply chain. The research focused on a small part of the supply chain, from suppliers in China to the port of loading where orders are loaded on a vessel to be transported to HEMA’s distribution centre in Utrecht. 

By means of literature research and/or expert interviews information was gathered about responsiveness of a supply chain, about HEMA’s supply chain, about the implications of more frequent ordering on various supply chain actors and about transport network scenarios. Three transport network scenarios were calculated and analysed thoroughly. For one of the scenarios a heuristic approach has been developed, partly based on a set partitioning model. The results showed interesting opportunities for HEMA.

In this research is examined in which way the current forecasting- and planning model of De Winter Logistics (DWL) can be expanded, to determine the required capacity in a disaggregated way. DWL is a logistics service provider in the horticultural sector and provides services for the Dutch growers and traders, directly or via the auction. Because of uncertainties about the orders that are placed, it is hard for DWL to make efficient use of vehicles and determine where and when the vehicles need to be deployed.

A disaggregated planning model is designed, by determining the amount of trolleys per transportation service and per time period, to be able to expand the current planning model of DWL in a disaggregated way. The disaggregated planning model translates the forecasted total amount of trolleys into required trucks and trailers per location of DWL by disaggregation of the forecasted total amount of trolleys, respectively into trolleys per trajectory, trolleys per shift, trolleys per time period, required hours, required trips, required vehicles and required trucks and trailers per location of DWL.

Shared logistics is a phenomenon more and more common in the retail sector in urban areas. Providing pickup service for external customers from other retailers can reduce driver waiting time and CO

emission, lead to higher efficiency in resource utilization, but this comes at the expense of extra costs. Whether the shared logistics service is profitable for the service provider remains to be quantified. In this thesis, a mathematic model is formulated to study the impact of providing pickup service for external customers on the service provider. The model is solved by a mathematical programming-based heuristic called Relax and Fix (R&F). Computational experiments result on Solomon benchmark and real-life instances show that R&F is generally an effective approach for solving the mixed delivery and pickup problem. Results on real-life instances suggest that shared logistics is promising in improving last-mile logistics’ efficiency in urban areas.

Modelling in supply chain management is mainly focused on two aspects: Minimize costs and maximize service. Growing environmental, governmental and economic pressure stimulate the implementation of sustainable development in companies worldwide. Green supply chain management aims to extend the traditional supply chains with activities that minimize environmental impact. This study aims to support companies in developing green supply chain management by including a third aspect in modelling: minimize CO₂ emissions.

To support decision making about the implementation of green supply chain management, an environmental assessment framework is constructed. The framework consists of a longlist with CO₂ reduction measures, structured by the categories: alternative fuels, fuel efficiency, intermodal transport, logistic network, and logistic alignment. Intermodal transport is quantified in multi-period multi-objective network design. The three objectives consider minimizing transportation costs, transportation time and CO₂ emissions. A case study helps to test the model, and results are obtained regarding the influence of an additional transportation mode, barge, on the objectives. The results also consider the required investment in transportation time and transportation costs to achieve a reduction in CO₂ emissions. Sensitivity analyses indicate the influence of the distance between the production site and consumer and the demand pattern of those consumers.

This research combines an MSc thesis and an internship project. It is part of a larger project funded by the Top Institute of Food and Nutrition (TIFN) which focuses on valorization of raw material and process efficiency in food supply chains. The objective is to develop a conceptual model that optimizes the production planning of mushroom cultivation in order to eliminate inefficiencies and improve sustainability. Multi-Criteria Decision Making techniques were used to quantify trade-offs between economic (e.g. profit) and environmental (e.g. exergy) indicators of sustainability and to identify inefficiencies in mushroom production. The model was developed and parameterized in close collaboration with the industry. Decisions related to when and how to product in order to meet demand were optimized while sensitivity analysis was conducted to identify opportunities for improvement.

We found out that exergy is a promising indicator of the environmental performance for mushroom production because it accounts for both quantity and quality of energy flows and losses. The cost of compost is a determinant factor for the re-use of compost and the quantities of produced wastes. Re use of compost becomes interesting if alternative technology that focuses on minimizing the costs related to pest and disease becomes available.

FAO reports food waste to be over 30% of the food production. To explore ways of reducing food waste, a DSS will be developed as part of a project of Top Institute Food and Nutrition. Within this DSS a simulation program simulates a food supply chain. One of the factors to simulate is the ordering by retailers. In this thesis approximations are derived for the control parameters in the (S,q,Q) policy and for the performance measures of outdating and the fill rate. A lost sales inventory system of perishable products for a retail environment is investigated, with periodic review, positive lead time, FIFO and LIFO withdrawal policies and a fixed shelf life. Demand is stationary, discrete and stochastic. Objective is minimising average outdating and shortage costs. For a broad Design of Experiments, by means of SDP and simulation these costs are minimised, and the optimal levels for the replenishment parameters and performance measures are derived. Using regression, formulas are estimated for order-up-to level S, minimum order quantity q, maximum order quantity Q, relative outdating, fill rate and determine the cost ratio by a certain fill rate. These formulas are also tested for a policy without q and Q (the order-up-to S policy), and by means of inter- and extrapolation from the DoE. Also for a realistic case from the TIFN project the regression models are tested on their performance. The final approximations are fast and perform very well. These fast and simple approximations can be used in practice by inventory managers, but also in other simulation studies to quickly determine values of replenishment parameters.

Gathering floor eggs by hand in a poultry house is very time consuming and requires a lot of physical effort. Thereby the project “Automation for poultry production” aims for the development of an autonomous egg gathering robot.

This MSc. thesis research contributes to this project by developing a path planning algorithm for the robot. The algorithm should produce an optimal path for gathering as much eggs as possible in the given time frame. Previous research on this topic resulted in a heuristic approach. Comparing the optimal solution with the heuristic enables benchmarking prior results.

The method used for this optimization is called Dynamic Programming (DP) which is widely used in various optimization disciplines, including Operation Research. Its use for path planning purposes is limited.  

After investigating the computational complexity, it is concluded that the optimal solution cannot be computed for a realistic problem size. Due to this restriction another heuristic has been developed which will be compared by simulation with results from prior research.

Three possible logistical scenarios of the supply chain of potted plants of FloraHolland were evaluated based on costs and throughput times. One scenario represents the current practice of the supply chain; the plants are transported from grower to the FloraHolland locations based on sales expectations. The plants are only sold at the location where they are physically present. In the second scenario the plants are transported from the grower to the geographically closest FloraHolland location. The plants can be bought at all locations and therefore interauction transport, after the auction, is necessary. In the third scenario the plants are transported to the FloraHolland locations based on sales expectations and the plants can be bought at all FloraHolland locations, which leads to interauction transport. A conceptual model of the supply chain was created and used as a blueprint for a computer simulation model that was used to simulate the scenarios. This research shows that the first scenario leads to medium costs and the lowest throughput times. The second scenario leads to the lowest costs and the highest throughput times. The third scenario leads to the highest costs and medium throughput times.

This thesis is performed in cooperation with TNO and the WUR. TNO reveals research questions on strategic horizontal co-operation in supply chains. Within this concept, a practical case of potential co-operation of five terminals at Maasvlakte 2 (Port of Rotterdam) is seen as a case study. The research question is how concepts from Game Theory can be used to study horizontal co-operation in terms of coalition formation of similar suppliers.  Game theory is a mathematical approach to study strategic behaviour of interdependent stakeholders in a decision making problem. To answer the question, we elaborate the literature on this topic and provide easy to grasp examples that reveal the necessary information to analyse the co-operation question. The case that will help to demonstrate how Game Theory can be used is that of the terminal co-operation. These terminals might consider to form a coalition to bundle their containers for transport per train in order to cope with distribution inefficiencies. The conclusion and recommendations of this study are related to how Game Theory can be used in similar coalition formation problems.

The focus of this research is on the development of a European logistics network for the Dutch floricultural market, based on the concept of the metro model, which connects all supply and demand locations via inbound and outbound hubs. This research evaluates the allocation of a number of VALs (Value Adding Logistics) activities along the supply chain, by optimizing the routes to be taken in these hubs. This thesis is composed by a first part, covered by a literature review, in order to get insights in the Dutch floricultural cluster and in the value adding activities currently performed; the second part is about the allocation of these activities into the metro model, by using Linear Programming, applied to a number of scenarios, which are created according to a case study of the Benelux representing a potential future transportation network. The results provide insights in how a certain VALs allocation impacts CO2 emissions, responsiveness, and transportation costs when products are routed optimally according to minimizing CO2 emissions, or minimizing costs, minimizing total response time. These insights can be used in exploring a suitable design of the network.

Van der Plas, one of the largest cut-flower exporters in the Netherlands, is constantly looking for new ways to improve business. The goal of this research is to get insight in the effects of pooling inventory on the performance of Van der Plas. The research focuses on Van der Plas’ locations in France. Several key performance indicators are determined and evaluated with respect to Van der Plas’ locations in France. The effect of pooling on the main performance indicator (cost) is analyzed and the optimal strategy for different scenarios is determined. A Literature Study, In-Depth Interviews and a Scenario Analysis are used as methods for this thesis. This research has shown that there are strong indications that pooling inventory can have a positive effect on the performance (reduction of cost) of Van der Plas.

This master thesis deals with the quick approximation of determining optimal order-up-to levels for a fixed-life time perishable products under the assumption that the demand is non-stationary. A lost sales inventory system is investigated, with periodic (R, S) order policy. After the analysis of the regression based approximation formulations for perishables as derived for stationary demand in an earlier MSc thesis,  new approximations for non-stationary demand are developed. These new approximations are tested in a simulation model in Matlab. It appears that setting order-up-to levels for non-stationary demand is not straightforward.

This thesis is done in combination with purchase organisation Superunie about the rethinking of logistical structures in the retail market. The goal of this MSc thesis is to determine key logistics collaboration concepts (LCCs) for Superunie in such a way that the benefits of collaboration in the supply chain will be clear for the members. This is done with a case on the AGF chain where supplier Fossa Eugenia has provided the analysed data and insight in the chain. The research question that will be answered is ‘

. First, the organisation Superunie is introduced and several theories about collaboration are discussed. The current situation of the AGF chain is sketched, and by having interviews problems and possible bottlenecks in the situation are formulated. The problems are based on not reaching the set norms of key performance indicators (KPIs). The used KPIs in this thesis are: delivery reliability, freshness and logistics costs. For the identifying of the main problems, cause-effect models are built for each of the KPIs. To exclude or improve the main problems, the most preferred scenario for Superunie is made which consists of a combination of the LCCs transport bundling and cross docking.  The combination of that two LCCs is also the answer on the research question of this thesis. To ‘test’ the scenario, a case study is done which focuses on supplier Fossa Eugenia that also has provided the data for the case study.

The goal of this MSc thesis is to get an overview of the mango process network and the corresponding supply chain network. An LP model is created to identify the relation between different tasks within the process network and the corresponding product portfolio. The effect of revenue prices of end products, energy use of processes, waste production and demand restrictions on the final outcome of the model in terms of quantities of produced end products is investigated. Both energy use and profit generation have a large influence on the product portfolio. Furthermore, an MILP model is created depicting the supply chain network and to study the effect of different production locations, transport cost variations and seasonal influences on the division of tasks over the available locations. Especially transport costs have a large influence on the product portfolio and facility openings. No difference in product portfolio was found between separate and integrated process network and supply chain optimization.

Wind energy can lead to a great socio-economic impact in Europe nowadays, while the installed capacity of wind power is estimated to be doubled by 2030.In order to generate power from the wind, a set of wind turbines is needed. A set of turbines is called a wind farm. The turbines of a wind farm are all connected via cables to the main power station.

For an optimal design of wind farms, accurate models are needed. Computational models on wind farm design vary in the existing literature and they have been developed by engineers and scientists with different backgrounds in order to meet all requirements. This thesis investigates the contribution of Operations Research scientists to these mathematical models. More specifically, an Integer Linear Model from literature has been taken as a starting point. This model aims to minimize the cabling costs for offshore farms. In order to understand the existing model, the structure has been modified and more requirements are considered. Besides the objective to optimize the cable routing, a sub-problem arose to facilitate the model by relaxing a specific type of constraints (i.e. the planarity constraint). The addition of a node in the existing grid turns out to be beneficial for specific cases, taking into account the fixed costs arising from the installation and maintenance.

In this thesis a framework is designed for the supplier evaluation and selection at Pactics. A multi-criteria decision-making technique is used, with elements of the Analytic Hierarchy Process to calculate weights and elements of the PROMETHEE method to score supplier performances. The framework is applied to evaluate Pactics’ current and potential RF0026 fabric suppliers.

Firstly, different divisions of Pactics have indicated which criteria they found important for the supplier evaluation and selection at Pactics, based on a longlist of criteria retrieved from the literature. Price, Delivery & Service, Quantity Flexibility and Suppliers’ SCM Capabilities are selected as economic sub-criteria, Environmental Documents, Environmental Friendly Products and Environmental Management Capabilities as environmental sub-criteria and Meeting Customer Requirements, Long-term Relationship Potential and Certification as social sub-criteria. Also, prerequisites are determined which the suppliers must meet in order to participate in the evaluation.

Thereafter, the relative importance of the (sub-)criteria are calculated with a pairwise comparison. Subsequently, with the use of indicators a questionnaire is designed to measure the performance of the suppliers on these (sub-)criteria. Their answers are scored and entered into the model. Finally, the model has provided a ranking of the suppliers with a score for each supplier between 0% and 100%.

Incorporating acceptability is a challenge for diet modeling. Data Envelopment Analysis (DEA) is proposed as an alternative approach to calculate healthier diets without explicitly introducing acceptability constraints. In the DEA diet models, evaluated diets are benchmarked based on a set of less-is-better (undesirable) and more-is-better (desirable) nutrients, and the choice of nutrients can affect the results of the analysis. This study explored the impacts of using different nutrient sets obtained from four selected Diet Quality indexes (i.e., the NRF6.3, NRD9.3, NRF11.3, and NRD11.4) on the model solution. Besides, the difference amongthe DEA diets models (i.e., the IO-DEA, OO-DEA, and ADD-DEA) was analyzed. These DEA diet models were used to improve the diets for the Czech Republic.

Generally, the more nutrients included in the DEA diet models, the more efficient diets, and less room forimprovement. The type of nutrients involved also influenced this association. The comparison results addressed the importance of selecting a suitable set of nutrients, which selection should be on a case-by-case base.The finding implicated that the DEA diet models can be used to design specific diets and the model output can provide policymakers with a direction to promote public health.