József Váncza

Engineering of Intelligent Systems

Ant colony optimisation is a relatively new meta-heuristic search technique for solving optimisation problems. To date, much research has concentrated on solving standard benchmark problems such as the travelling salesman problem, quadratic assignment problem and the job sequencing problem. In this paper, we investigate the application of ant colony optimisation to practical telecommunication design and synthesis problems having real-world constraints. We consider a modelling approach suitable for ant colony optimisation implementation and compare the results to the simulated annealing meta-heuristic.

Genetic algorithms in process planning

Abstract The paper discusses the flaws of classical planning methods and outlines a new approach by which a large portion of domain-related knowledge can be represented and passed to a learning method using genetic machinery.

Computer aided process planning for sheet metal bending: a state of the art

Purpose of this paper is to offer the reader an overview of recently performed and ongoing research related to process planning for sheet metal bending, thus providing a starting point for further exploration of this field. The scope of this review paper is limited to sheet metal bending as performed on numerically controlled press brakes, with special focus on air bending. Automatic process planning requires a good understanding of the material behaviour under process conditions. Therefore, some space has been reserved for an overview of bend modelling efforts and, directly linked to this, in-process measurement and adaptive control methods. Part representation and feature classification methods for bent sheet metal parts are also discussed. Sections are dedicated to the core problems of fully automated process planning in sheet metal bending: bend sequencing, collision detection, tolerance verification and tool selection. The state of the art review is completed with an overview of ergonomic analysis methods for process plan evaluation.

Aggregation - the key to integrating production planning and scheduling

In this paper we suggest an integrated planning and scheduling framework with a special emphasis on the link between these control levels. Our planning model is generated automatically by performing aggregation on de facto standard product and technology related data in the dimensions of time, resource capacities and operations. The method addresses make-to-order production environments. An industrial case study is also presented, demonstrating how our algorithms work on large-scale problem instances.

An agent model for incentive-based production scheduling

Abstract In agent models of manufacturing it is hard to reconcile autonomy and cooperation. The paper proposes a solution to this problem within the context of a dynamic production scheduling problem. Our organizational model is based on economic concepts, uses market rules and an incentive mechanism. The solution integrates dynamic order processing, advance least-commitment scheduling and dispatching.

Project Scheduling Approach to Production Planning

Abstract We suggest a novel approach to modelling and solving production planning (PP) problems in make-to-order production environments. This approach unifies the capacity and the material flow oriented aspects of PP. Orders are modeled as projects that compete for limited resources. The projects consist of networks of variable-intensity activities which may require several resources at the same time. The goal is to generate production plans that satisfy all the temporal and resource constraints and minimize additional or external resource usage over the planning horizon. The model is applicable at different aggregation levels of PP, as we show with two real-life case studies. Although the capacity and material flow aspects of PP are coupled, a special solver developed for the project model efficiently solves problems of real-life sizes.

Constraint-based process planning in sheet metal bending

Abstract The majority of research dealing with computer-aided process planning of sheet metal bending approaches this problem as heuristic search. Since relevant engineering knowledge mostly consists of declarations that prohibit collisions and just a handful of generative rules, there are no useful means to drive these heuristics. In order to find a new way, we have made experiments with a constraint-based approach: using predefined constraint types and geometric constraint satisfaction, complex bending problems have been solved. By returning not just a single solution but a Pareto-optimal set of solutions (i.e., operation sequences, with appropriate part orientations and tools assigned) we have left the engineers freedom to apply further, not yet modeled parts of their domain knowledge.

A distributed coordination mechanism for supply networks with asymmetric information

The paper analyses the problem of coordination in supply networks of multiple retailers and a single supplier, where partners have asymmetric, private information of demand and costs. After stating generic requirements like distributedness, truthfulness, efficiency and budget balance, we use the apparatus of mechanism design to devise a coordination mechanism that guarantees the above properties in the network. The resulting protocol is a novel realisation of the widely used Vendor Managed Inventory (VMI) where the responsibility of planning is at the supplier. We prove that together with the required generic properties a fair sharing of risks and benefits cannot be guaranteed. We illustrate the general mechanism with a detailed discussion of a specialised version, assuming that inventory planning is done according to the newsvendor model, and explore the operation of this protocol through computational experiments.

Product line development with customer interaction

Abstract While customizing their products, manufacturers attempt to fulfill specific requirements of the customers within the constraints dictated by the manufacturing (design, planning and production) environment, and by the economical necessity of earning profit. This paper offers a generic framework that captures more technical features of this problem than the marketing models: in addition to customer welfare and profit maximization considerations, engineering aspects are made operational, too. Driven by the interaction between customer preferences and the reallocation of manufacturing resources, viable product families emerge from a variety of technically feasible product alternatives.

Coordinating Supply Networks in Customized Mass Production: – A Contract-Based Approach

In the paper we discuss conflicting performance requirements in customized mass production and suggest a novel cooperative planning method for sharing information and coordinating decisions between a focal manufacturer and its suppliers. The method strives to achieve high service level and minimal expected average costs—including production, inventory and potential obsolete inventory costs. A channel coordination mechanism drives the overall system towards its right behavior even though the partners make planning and scheduling decisions autonomously. We present the mechanism and discuss its properties on simulated test cases taken from an industrial case study.