104 research outputs found
On the Implementation of Lean Production in Manufacturing SMEs
No full textContains fulltext :
282673.pdf (Publisher’s version ) (Open Access)Radboud University, 27 oktober 2022Promotor : Lauche, K. Co-promotores : Schouteten, R.L.J., Slomp, Jannes261 p
The shift team formation problem in multi-shift manufacturing operations
No full textThis paper addresses the problem of assigning operators to teams that work in single-, two-, or three-day shift systems. The problem was motivated by, and illustrated with a case situation encountered in Dutch manufacturing industry. The problem addressed forms an extension of cell formation problems which are currently in the phase of addressing labor-related issues in cell design. A generalized goal problem formulation is presented to address multiple, conflicting objectives covering cross-training of workers, ensuring adequate levels of labor flexibility and minimizing labor-related costs. The proposed solution procedure consists of two phases. In the first phase, shift systems, in which applicable machines and the sizes of each shift team are identified. The next phase deals with assignment of operators to various teams and identification of specific cross-training needs for various workers. This phase involves the use of interactive goal programming. The methodology is illustrated by details from the case situation as well as a numerical example.
Biogeochemical redox proxies in sediments from Schandelah during the Toarcian (Early Jurassic)
No full textAuthor contributions:
The sampling was led by Bas van de Schootbrugge and measurements performed by Nina Papadomanolaki, with supervision of Niels A. G. M. van Helmond and Caroline P. Slomp. Measurements were gathered, processed and analysed by Itzel Ruvalcaba Baroni
Optimality, flexibility and efficiency for cell formation in group technology
No full textHet onderzoek van Dmitry Krushynskyi concentreert zich op de ontwikkeling van mathematische modellen voor celformatie (CF), die in de praktijk kunnen worden gebruikt om bedrijfsprestaties te verbeteren. Hoewel al meer dan 50 jaar onderzoek is gedaan naar het CF-probleem, baseren de meeste methoden zich op intuïtieve overwegingen en kampen ze onder meer met modellerings- en rekenfouten. Een ander nadeel van de meeste bestaande modellen is hun gebrek aan flexibiliteit: als een model op een ad hoc-procedure is gebaseerd, veroorzaakt elke nieuwe beperking een belangrijke wijziging van het model. In het proefschrift worden twee modellen ontwikkeld.
The thesis focuses on a development of optimal, flexible and efficient models for cell formation (CF) in group technology. By optimality is meant guaranteed quality of the solutions provided by the model, by flexibility - possibility of taking additional constraints and objectives into account, by efficiency - reasonable running times. The main aim is, thus, to provide a reliable tool that can be used by managers to design manufacturing cells based on their own preferences and constraints imposed by a particular manufacturing system.
Though the CF problem has been extensively studied for more than 50 years, there have been very few attempts of solving the problem to optimality and almost all the proposed models for CF problem are either of intuitive (heuristic) nature or are solved by heuristic procedures. This means that the obtained solutions incorporate two types of errors: an intrinsic error of modelling and a computational error induced by a heuristic solution procedure.
The author proposes two models based on the p-Median and the minimum multicut problems, respectively. The first model has very short running times (usually less than 1 sec.) at a cost of a small modelling error. The second approach excludes the modelling error but has substantially larger (yet, practically acceptable) running times. Both models are expressed in terms of Mixed Integer Linear Programs and require a general-purpose MILP solver, like CPLEX or Xpress. Several realistic constraints and objectives, as well as the ways of introducing them into the proposed modes, are discussed.
Lean beyond waste: Towards the reduction of variability and buffers in healthcare
No full textIn de zorg is Lean een populaire manier van procesverbetering en het reduceren van verspillingen is een speerpunt in een Lean aanpak. Naast het reduceren van deze verspillingen worden Lean initiatieven ook geacht zich te richten op variabiliteit en de hier uit voortkomende buffers. Er wordt onderscheid gemaakt worden tussen natuurlijke en kunstmatige variabiliteit. Deze kunstmatige variabiliteit komt voort uit ons eigen handelen en moet worden gereduceerd. In een zorgomgeving zijn voornamelijk tijds- en capaciteitsbuffers van toepassing. Naast deze reeds bekende buffervormen is er in dit proefschrift ook uitgebreid aandacht voor een ander buffermechanisme: het bufferen met bewerkingstijd. De resultaten in dit proefschrift dragen bij aan de basis van Lean theorie. In vier onderzoeksprojecten richten we ons op de rollen van variabiliteit en buffers, aspecten van Lean volwassenheid. Ondanks het grote aantal bestudeerde interventies in het eerste onderzoeksprojecten zijn er slechts enkele interventies die aantoonbaar variabiliteit reduceren en doorlooptijd verkorten. Het overgrote deel van de interventies blijkt zich te richten op het reduceren van duidelijke verspillingen. We laten zien dat een relatief kleine kennisbijdrage de focus van de interventies weet te verbreden. Dit proefschrift identificeert meerdere mogelijkheden om Lean in de zorg effectiever toe te passen
A épica da pobreza: mulheres imigrantes
No full textBetween the nineteenth and the twentieth centuries the Italian emigration to the Brazilian state of Rio Grande do Sul was predominantly familiar and included in the system of small peasant properties planned by the local government. Historiography has ignored for decades the role of immigrant women in this context and the author of this essay was among the first scholars to get them out of the shadows. Summarizing part of the results of two extensive research, Loraine Slomp Giron follows here the paths of women who, by becoming owners or small businesswomen, have left traces of themselves in the archives and in memory. Stories of women highlighting the creative adaptation to a situation of double marginality, social and gender-based, in the daily struggle against poverty
Production control for a flexible manufacturing cell
No full texthttp://deepblue.lib.umich.edu/bitstream/2027.42/36118/2/b1723777.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/36118/1/b1723777.0001.001.tx
Virtual cellular manufacturing : relevance and development of heuristics for family-based dispatching
No full textIs it possible to achieve short throughput times in small-batch parts manufacturing operations? Even when a high variety of parts is required, in fluctuating volumes, and with a low to medium annual demand? Virtual Cellular Manufacturing may be one of the answers to the challenges that parts manufacturers face, as the research in this thesis shows.
Virtual cells are groups of resources (e.g. machines, workers), each dedicated to the manufacturing of a part family. These virtual cells help to realise the favourable throughput time performance of conventional manufacturing cells. However, the cells are only formed virtually in the planning and control system. Therefore they can relatively easily be adapted to changed circumstances, without the need for expensive layout changes on the shop floor.
The first part of this thesis focuses on the exploration of the relevant literature on Virtual Cellular Manufacturing. Next, three case studies show the applicability of Virtual Cellular Manufacturing in a practical context. The second part presents three simulation studies of family-based dispatching heuristics (one specific implementation of Virtual Cellular Manufacturing) in basic, but realistic, shop configurations. The results show that family-based dispatching heuristics can achieve significant reductions of throughput times. The findings of this thesis may therefore be relevant to many small-batch discrete parts manufacturing companies.
The concept of enmity in the political philosophy of Hobbes
No full textTo the author’s knowledge, this is the first systematic study of the concept of enmity in the political philosophy of Thomas Hobbes. Examining this important category does not only elucidate the concept itself, but also provides an opportunity to reconnect fragments of Hobbes’s thought that are increasingly being treated as disparate subjects. It is suggested that the notion of enmity can shed further light on related aspects of his political philosophy, including human competitiveness, the roles of fear and trust, the evil of violent death, the status of rebels, and his theory of international relations. In addition, the subject invites a rethinking of Hobbes’s place in the history of political thought. It is argued that he was among the first to make enmity a central subject of political philosophy. This seems to be related to Hobbes’s break with the traditional notion of natural sociability, as a consequence of which he describes the natural condition of mankind as a war of all against all. Although Hobbes depicts human beings as natural enemies, he holds that enmity does not exclude the possibility of reconciliation; individuals can supposedly overcome their hostility through subjection to a sovereign. These views give rise to a dynamic distinction between public and private enmity, according to which outright hostility can be transformed into private rivalry if human beings renounce their natural right of war. Conversely, subjects become public enemies if they rebel against the sovereign. Hobbes’s views on natural enmity and reconciliation also have important implications for his theory of international relations. This thesis particularly highlights the possibility that states can be decomposed and reassembled after a foreign invasion, which precludes wars of annihilation
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