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In this study, we consider a production lot-sizing and scheduling problem found in the fruit juice production industry from an enhanced inventory management perspective. The problem can be classified as a P2SMM (two-stage multi-machine lot-scheduling) problem. We extended the classical P2SMM problem by incorporating an additional inventory management aspect of finished products to reflect a possible real-life case problem, specifically regarding the shelf-life concept and limited warehouse capacity, with a possibility of outsourcing the warehousing demand to a third-party logistics company. We developed the mixed integer linear programming (MILP) model to fully represent the considered problem (due to the NP-hard nature of the problem, only small-scale instances could be solved to optimality), and the hybrid variable neighborhood search with linear programming (VNS/LP) model to solve both small and real-life large-scale problem instances. The goal of the developed models is to minimize total costs that consist of the cost of backordering, the cost of planned minimum and maximum stock level violation, the cost of warehouse capacity overflow, the costs of production setup time and unused available production time. The main idea of the VNS/LP model is to solve the scheduling segment of P2SMM (the production sequence) via a VNS heuristic, and the lot-sizing segment of P2SMM via the linear programming (LP) model. Based on the results from five variants of the problem setup, a potential decision maker can have an overview of the impact of different important input parameters (production time costs, warehouse capacity and costs, inventory related costs and production demand) on the total cost of a production process and improve its efficiency in changing conditions. [ABSTRACT FROM AUTHOR]

Rapid urbanization, intensified industrialization, rise of income, and a more sophisticated form of consumerism are leading to an increase in the amount and toxicity of waste all over the world. Whether reused, recycled, incinerated or put into landfill sites, the management of household and industrial waste yield financial and environmental costs. This paper presents a modeling approach that can be used for designing one part of recycling logistics network through defining optimal locations of collection points, and possible optimal scheduling of vehicles for collecting recyclables. [Projekat Ministarstva nauke Republike Srbije, br. TR36005]

This article presents a bi-objective mixed-integer linear model for the waste management system design. Two types of facilities, landfills and transfer stations (TSs), are identified based on two objectives: minimising the total system's costs and the total negative impact of located facilities on end users as waste generators through a defined pollution decay function. Landfills and TSs are categorised as undesirable facilities due to associated environmental risks. In this article undesirability of a located facility is defined as a two-threshold linear decreasing function of the distance between the end users and the located facility. Also, we considered additional restrictions that no two selected landfills or TSs are within a pre-specified distance from each other, limiting the superimposed pollution generated in these facilities. The model performances are tested on a real-scale example for Vojvodina (Serbia). Results showed that the proposed model has potentials and can be beneficial for government organisations, local authorities and other organisations related to waste management issues. [ABSTRACT FROM AUTHOR]

The number and locations of facilities represent the most important decisions when modeling service networks. The facility location problem in the context of service networks is predetermined by the investment costs and/or achieving a certain standard of satisfying users' demand. Systems designed in this way are based on the idea that they will function in regular exploitation conditions, without any interference. However, various adverse events caused by intent, unintentional human activities, technological disasters or natural disasters can lead to a partial or complete cessation of the service networks. For the first time, this paper highlights the importance of the impact assessment of disruption events on the service networks where the r-interdiction median location model is presented as a potential solution approach in a case when these events occur. Also, an extensive overview of the state-of-the-art literature is provided. Finally, a numerical example of the determination of the most vulnerable points of service networks is given to illustrate the effects of potential disruptions, as well as appropriate preventive actions that eliminate or at least mitigate those situations. [ABSTRACT FROM AUTHOR]

Because order picking is the most demanding, the most labor intensive and, accordingly, the costliest activity in a warehouse it has been potential for the optimization from different points of view and at different decision-making levels. In this research our goal was to examine a possible improvement of the order picking process by reducing the potential of the aisle congestion which is quite frequent in order picking systems with lots of pickers passing through same isles simultaneously. For that purpose, we give a quadratic mixed integer programming solution approach, as well as a Variable Neighborhood Search based heuristic algorithm solution approach. Beside that we employ a reduction-based strategy for reducing running times of the heuristic algorithms. Eventually, we tested the efficiency of developed models on an imaginary order picking system. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of vehicle routing in drayage operations, where vehicles can carry containers of different sizes. The multisize container drayage problem with time windows is modeled as a multiple matching problem and formulated as a mixed integer linear program (MILP) model. The proposed MILP model determines optimal pickup and delivery routes of vehicles and is applicable to any type of vehicles capable of simultaneously transporting any arbitrary number of 20- and 40-ft containers. To solve larger sized problems, we proposed a variable neighborhood search (VNS) heuristic. Both MILP and VNS approaches have been tested on numerous test instances and their performances are reported. [ABSTRACT FROM AUTHOR]

Problem observed in this research is inspired by distribution of parcels in courier service where city area is divided into service zones based on the historical data of deliveries intensities and city structure. Each service zone is served by own vehicle of known limited capacity. Number of deliveries per zone varies between days, where average intensity is known in advance. Additionally, total number of deliveries can exceed capacity of the vehicle. All exceeded deliveries in service zones must be served by the "sweep" vehicle. Main idea of our paper is to evaluate the impact of fixed and flexible zoning strategies on total traveled distance of vehicles in the parcel distribution. In fixed zoning strategy deliveries cannot be transferred, whereas in flexible zoning these deliveries can be transferred between zones. For the purpose of solving problems of realistic size we use heuristics approach, while Mixed Integer Programming (MIP) model was developed to solving the small scale problems. [ABSTRACT FROM AUTHOR]

Gravel distribution by inland waterway transport is characterized with very intensive material flows and very low profit margins. Therefore, gravel distribution companies are in constant efforts on improving system efficiency by increasing productivity of existing facilities. Barges' unloading activity is executed at the end of inland waterway transport process and has a large influence on productivity of whole system, since minimization of time that barges spend waiting for services maximize time they transport gravel, i.e. their productive time. In this paper, we transfer this optimization problem in a well known class of multiple traveling repairman problem with time windows. Due to time consuming solution process in case of real size problem instances, beside optimal mathematical formulation of the problem we present solution approach based on Variable Neighborhood Search metaheuristic algorithm. [ABSTRACT FROM AUTHOR]