Axel Tuma

Energy-efficient scheduling in manufacturing companies: A review and research framework

Because sustainable scheduling is attracting increasing amounts of attention from many manufacturing companies and energy is a central concern regarding sustainability, the purpose of this paper is to develop a research framework for “energy-efficient scheduling” (EES). EES approaches are scheduling approaches that have the objective of improving energy efficiency. Based on an iterative methodology, we review, analyze, and synthesize the current state of the literature and propose a completely new research framework to structure the research field. In doing so, the three dimensions “energetic coverage”, “energy supply”, and “energy demand” are introduced and used to classify the literature. Each of these dimensions contains categories and attributes to specify energy-related characteristics that are relevant for EES. We further provide an empirical analysis of the reviewed literature and emphasize the benefits that can be achieved by EES in practice.

Configuration and coordination of virtual production networks

Abstract Following the actual discussion concerning modern production concepts, the term “virtual production” or “virtual enterprise” plays an increasingly important role. The idea of virtual enterprises is to implement modern management trends like “concentration on core competencies”, “distributed production” and “maximal customer orientation” by the application of advanced computer and telecommunication systems and services like “global networking” or “groupware systems”. The objective is to establish a certain kind of a “Best of everything Organization” by a synergetic combination of core competencies of single partners (centers of competence) in order to perform a given business project to a maximum degree of customer satisfaction. Important features are a distinct form of network organization in combination with a high degree of organizational flexibility. Taking into account Williamsons theory of transactions costs, virtual enterprises can be interpreted as a certain kind of an intermediate organizational form between the institutional poles: market and hierarchical structured enterprises. According to this an evaluation will be given on the basis of transaction costs. In the following section structural and process-orientated questions of virtual production systems are formulated. From the viewpoint of production science, especially the allocation of sub-tasks to adequate project partners and the harmonization of distributed production processes in a network of independent companies seems to be very interesting. Principally, the decision support systems for such problems can be based on hierarchical or distributed control strategies. The characteristics of virtual production systems imply the application of decentralized approaches (e.g. multi-agent systems). A very interesting approach in this context is the application of distributed problem-solving strategies like contract networks.

A comparison of fuzzy expert systems, neural networks and neuro-fuzzy approaches. Controlling energy and material flows

Abstract In industrial production processes, materials and different forms of energy are provided, transformed respectively converted, stored and transported. With this process joint products in different states of aggregation are emitted. Environmental impacts can be identified at any stage of the energy and material flow process. Due to the fact that production units and processes are interconnected with energy and material flows, it is of special interest to develop production control mechanisms which control the energy and material streams in a way that utilizes available resources most efficiently and reduces emissions and by-products caused by the production process. These production control strategies have to consider variations in the input and output flows of succeeding and preceding production units. The development of production control strategies depends especially on the structure of integrated production systems. If it is possible to influence the energy and material flows by the selection of special production processes and an adequate allocation of jobs and aggregates, the construction of production control strategies can be reduced to a combined scheduling and technology selection problem. Methodical production control strategies can be based on optimal algorithms (e.g. dynamic programming) heuristics (e.g. rule-based approaches) and methods of machine learning (e.g. neural networks). Due to the complexity of real production systems, it is advisable to use rule-based approaches or neural networks depending on the structure of the available production knowledge.

Conception of a Novel Open Source Environmental Management Information System Design to Assess the Availability of Resources: Status Quo and Directions for Future Research

Resources for new technologies are vitally important and limited in their availability. The reasons for the limited availability are political tension, supply concentrations or restricted potential for substitution and recycling. The consideration of information on the availability requires the mapping of this information in business information systems. Science and practice lack holistic and integrated solutions whose use supports the availability and evaluation of sustainable developments. Taking account of open source software, a concept of environmental management information systems is under development, in order to measure sustainable availability. The integration of existing IT systems and data sources provides an improved assessment of risks. The article shows a concept of IT architecture which can be used as open source software in the regulatory framework of environmental management information systems in order to evaluate the availability of resources and course of action.

Using Fuzzy-Directed Agents For Ecological Production Control

Abstract Environmental impacts can be identified at any stage of the energy and material flow process in modern production systems. Due to the environmental situation and the constraints given by emission laws the demand for Ecological Production Control Systems (EPCS) increases. The objective of EPCS is the fulfilhnent of economical goals (e. g. the maximization of production rates) taking into account environmental constraints like the reduction of emission and energy flows. Though the optimal control of a production plant per se is anon-trivial problem, the complexity of the task increases under ecological constraints. We propose anagent-oriented model for the EPCS based on a petri net system model. The system control is decentralized by giving the agents satisfaction criteria based on a fuzzy decision model and by using negotiation strategies to resolve conflict situations. Technically the agent-oriented EPCS model is best suited for a real distribution of a production control system to a computer net...

A Hybrid Meta-Heuristic for the VRPTW with Cluster-Dependent Tour Starts in the Newspaper Industry

The newspaper industry implies a special optimization problem: Vehicle routes have to be executed directly after print finalization in order to supply customers in time. Hereby, the underlying vehicle routing problem with time windows has additional constraints: heterogeneous editions per vehicle and cluster-dependent tour starts due to differing completion times of editions. In this contribution, this problem is defined as a vehicle routing problem with time windows and cluster-dependent tour starts (VRPTWCD), caused by the allocation of editions to clusters and different edition completion times. This implicates the need for a new solution procedure. The well known methods Ant Colony Optimization and Tabu Search are combined and enhanced by additional parameters, resulting in a first approach (named AntTabu) for solving the VRPTWCD. This hybrid meta-heuristic, integrated in an application software for the newspaper industry, is applied to a real life application case of one of the largest newspaper companies in Germany.

Evaluating component recycling strategies

European environmental legislation aims at inciting manufacturers to close their supply chain by explicitly encouraging the reintegration of used components. Though this approach seems to be “ecologically correct”, the reluctance of several original equipment manufacturers (OEMs) and the low level of diffusion of remanufacturing activities indicate that component recycling does not always economically make sense. The purpose of this paper is twofold: identify critical factors for the success of recovery operations and hereby explaining OEMs’ behavior concerning component recycling strategies. In this context an optimization model is discussed taking into account parameters such as life cycle duration, reverse flow distribution, technical compatibility and customer expectations. Finally, we present two interesting insights gained by the application of the model.

Development of emission orientated production control strategies using fuzzy expert systems, neural networks and neuro-fuzzy approaches

In industrial production processes, materials and different forms of energy are provided, transformed respectively converted, stored and transported. In common with this process joint products in different states of aggregation are emitted. Environmental impacts can be identified at any stage of the energy and material flow process. Due to the fact that production units and processes are interconnected with energy and material flows, it is of special interest to develop production control mechanisms, which control the energy and material streams in a way that utilise available resources most efficiently and reduce emissions and by-products caused by the production process. These production control strategies have to consider variations in the input and output flows of succeeding and preceding production units.

Entwicklung emissionsorientierter Produktionsabstimmungsmechanismen auf der Basis fuzzyfizierter Expertensysteme und Neuronaler Netze

In industriellen Produktionsprozessen werden zur Herstellung von Marktprodukten Stoffe und Energiearten bereitgestellt, umgeformt bzw. umgewandelt, gelagert und transportiert. Gemeinsam mit diesem Prozes der Leistungserstellung werden als Kuppelprodukte Stoffe in flussigen, gasformigen und festen Aggregatzustanden emittiert. Dadurch ergeben sich umweltbelastende Auswirkungen im Verlauf des gesamten Stoff- und Energieflusprozesses. Da auf betrieblicher und uberbetrieblicher Ebene Produktionsprozesse durch Stoff- und Energiestrome miteinander verbunden sind, ist die Entwicklung von Produktionsabstimmungsmechanismen, welche diese unter Berucksichtigung vor- und nachgeschalteter Produktionsstufen so steuern, das die zur Verfugung stehenden Ressourcen moglichst effizient ausgenutzt und durch den Produktionsprozes enstehende Emissionen und Abfallstoffe, soweit dies technisch moglich ist, vermindert werden, von besonderer Bedeutung.

Assessment of agroforestry residue potentials for the bioeconomy in the European Union

The biobased chemical industry is characterised by strong growth. Innovative products and materials such as biopolymers have been developed, and current European demand for biopolymers exceeds the domestic supply. Agroforestry residues can serve as main sources of the basic building blocks for chemicals and materials. This work assesses sustainably available agroforestry residues to feed a high added-value materials and product bioeconomy. To evaluate bioeconomic potential, a structured three-step approach is applied. Cultivation practices, sustainability issues, legislative restrictions, technical limitations and competitive applications are considered. All data regarding bioeconomic potential are processed on a regional level and mapped by ArcGIS. Our results identify wheat straw as the most promising source in the agricultural sector, followed by maize stover, barley straw and rape straw, which all contain a total concentration of lignocellulose of more than 80% of dry matter. In the forestry sector, residue bark from two coniferous species, spruce and pine, is the most promising source, with approximately 70% lignocellulose. Additionally, coniferous bark contains considerable amounts of tannin, which has attracted increasing interest for industrial utilisation. A sensitivity analysis concerning removal rates, residue-to-crop ratios, changes in farming technologies and competing applications is applied at the end of the study to consolidate our results.