Grubbström's well-developed MRP Theory has been mostly used in modeling production processes. Global supply chains also contain distribution, consumption and recycling processes. For this reason theory was recently further extended to incorporate all kinds of activities. Such extended model, which consists of four main sub-systems, is closed and can be used for several detailed analyses. Since the importance of reverse logistics is increasing, this paper will focus on parameters which determine Net Present Value of the whole system, depending on geographical location of recycling facilities. We will show how lead times, transportation costs, setup costs and price of labor and energy of individual location contribute to overall NPV of the system. The article is particularly important because it is the basis for building a simulator for the evaluation of different decisions on decision variables relevant for economy, demography and land use, environment and energy in the area, which is in details presented in the appended article "Net Present Value evaluation of energy production and consumption in repeated reverse logistics.", accepted in publication in category A" journal. Already in 2011 and 2012, when we carried out simulations with VENSIM [ID 2259299], we find that in our study VENSIM is not the best platform therefore we tried to developed our own simulator, which we succeeded.
COBISS.SI-ID: 2315363
In this paper we extend and apply MRP theory towards reverse logistics including the considerations of transportation consequences. Our aim is to demonstrate the versatility obtained from using MRP theory when combining Input–Output Analysis and Laplace transforms. This enables an analysis of a supply chain including four sub-systems, namely manufacturing, distribution, consumption and reverse logistics, where the geographical distance between the activities play an important role. The main focus in this paper is on reverse logistics (recycling, remanufacturing). Especially we wish to model the evaluation of disposal and reverse activities far away from agglomerations, which often means an improved environment for nearby inhabitants. This is also illustrated in a numerical example. We use the Net Present Value as a measure of the economic performance. Our ambition is to show that supply chain sub-systems may accurately be described using input and output matrices collected together in corresponding matrices for the system as a whole. Activity levels in each sub-system govern the speed of the respective processes, and these activity levels, in general, will be considered as decision variables. We now analyse reverse logistics activities in which the flows of materials and goods are typically divergent (arborescent processes), similar to properties of the distribution sub-system, and recent results on the extensions of basic MRP theory introducing the concepts of output delays and the generalised output matrix are also introduced here, when modelling the reverse logistics sub-system.
COBISS.SI-ID: 2230883
After crisis in 2008 the retirement age of industrial workers in national pension schemes is rising or workers are loosing their job, which often appears very controversial. However, many industrial workers are not able to work until they have reached the increased retirement age. This problem is decreasing social security, increasing workers anxiety regarding the future and influencing the quality and timing of production processes. Disruptions and lower quality items produced in one activity cell of a supply chain can have a ripple effect throughout an entire supply chain. To solve this problem, we should put in place supplementary occupational pension schemes, which would compensate firms for the depreciated ability of their elderly workers to work when they have reached the previous retirement age but have not yet reached the new, higher retirement age. This article is introduces a model that is based on extended MRP Theory. The model can be used as a basis for negotiations between employers and employees to keep production at the same level of quality. The trade-off between higher contributions to supplementary occupational pension schemes and lower added values is considered. Contributions enable the early retirement of industrial workers at one or more workplaces in a supply chain, while lower added value is the result of lower quality and the perturbed timing of items that are produced in one or more activity cells of a supply chain: these issues have a ripple effect throughout an entire supply chain. The net present value approach is used. Based on this consideration we also assumed later in papers which followed this article, how to include also reverse mortgage to improve quality of life of seniors also if they are not able to work properly on there working places. We explained how it would influence liquidity of housing market.
COBISS.SI-ID: 17704754
The paper presents the changes in the parameters of attractiveness of regional centers before and after the onset of the crisis. The parameters in logit model were evaluated like ration of employability, wages, property prices and other factors that affect the attractiveness of central places.
COBISS.SI-ID: 2048200962
Chapter in a monograph which on the bases of the fuzzy logic describes the attractiveness of European regions. We have been informed that this chapter is included in the first quartile of chapters in Springer's e-books.
COBISS.SI-ID: 2259555