Scalability is a key feature of reconfigurable manufacturing systems (RMS). It enables fast and cost-effective adaptation of their structure to sudden changes in product demand. In principle, it allows to adjust a system's production capacity to match the existing orders. However, scalability can also act as a "safety buffer" to ensure a required minimum level of productivity, even when there is a decline in the reliability of the machines that are part of the machine tool subsystem of a manufacturing system. In this article, we analysed selected functional structures of an RMS under design to see whether they could be expanded should the reliability of machine tools decrease making it impossible to achieve a defined level of productivity. We also investigated the impact of the expansion of the system on its reliability. To identify bottlenecks in the manufacturing process, we ran computer simulations in which the course of the manufacturing process was modelled and simulated for 2-, 3-, 4- and 5-stage RMS structures using Tecnomatix Plant Simulation software.

This study explores the optimal pricing and investment decision for two competing green supply chains, both consisting of a manufacturer and an exclusive retailer. Our focus is to explore, does the strategic integration decision with rivals at the horizontal level or with partners at the vertical level have any effect on green product types? The results reveal the following insights: retailer-retailer strategic integration at downstream level leads to a sub-optimal total supply chain profit and green quality level for a development-intensive green product. Two competing manufacturers can produce products at a higher level if they are vertically integrated with respective retailers. Manufacturer-manufacturer integration at upstream level sometimes leads to higher profits and product quality level if cross price-elasticity of consumers is high. However, an opposite phenomenon is observed while they are selling for a marginal-intensive green product, horizontal integration can improve green quality levels, but supply chain members will receive a lower profit. Therefore, selection of green product types and strategic integration decision are interrelated to achieve the profit maximization goal along with the aim to offer products at a higher green quality level. Vertical integration strategy can outperform horizontal integration strategy, especially if cross-price elastic for green products remain high.

Highlights Four phases can be distinguished in the spread of the virus. The relative daily change indicator best visualizes the changes in the epidemic. We present the changes in the epidemic phases for a number of selected countries. The re-outbreak phase is probably the expected second wave of the epidemic. An updated, well-commented Matlab file is available in the open GitHub repository.

This paper focuses on a teacher allocation problem that is specifically concerned with assigning available academic lecturers to remaining courses from a given student curriculum. The teachers are linked to tasks according to competencies, competence requirements enforced by the curriculum as well as the number and type of disruptions that hamper the fulfilment of courses. The problem under consideration boils down to searching links between competencies possessed by teachers and competencies required by the curricula that will, firstly, balance student needs and teacher workload and, secondly, ensure an assumed robustness level of the teaching schedule. The implemented interactive method performs iterative solving of analysis and synthesis problems concerned with alternative evaluation/robustness of the competency framework. Its performance is evaluated against a set of real historical data and arbitrarily selected sets of disruptions. The computational results indicate that our method yields better solutions compared to the manual allocation by the university.

Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl Eryk SzwArc Grzegorz BocEwicz zbigniew BAnASzAk Jarosław wikArEkCompetenCe alloCation planning robust to unexpeCted staff absenteeism planowanie przydziału kompetenCji odpornego na nieprzewidziane absenCje praCowników*In order to deal with unexpected events such as employee absenteeism and/or a demand for personnel that is higher or lower than expected, organizations need to adopt proactive and reactive scheduling strategies to protect the personnel roster and to respond to this operational variability, respectively. In this paper, we discuss a proactive approach that exploits the concept of employee substitutability to improve the flexibility of a personnel shift roster to respond to schedule disruptions. With a view to developing a DSS-driven method dedicated to competence allocation planning robust to unexpected staff absenteeism, we present the concept of the so-called robust employee competence structure. A declarative model of the concept allows to find an employee competence structure robust to a given set of disruptions while guaranteeing an admissible personnel allocation to the assumed set of tasks.Since the problem of designing such a robust structure is NP-hard, another goal of the present study is to propose a sufficient condition the fulfilment of which will guarantee the validity of calculations. Potential applications of the proposed solution are discussed using examples.