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Evaluating organizational antifragility via fuzzy logic : the case of an Iranian company producing banknotes and security paper

Ghasemi A., Alizadeh M.

Operations Research and Decisions

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2017

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Vol. 27, No. 2

21--43

EN

The concept of antifragility has received much attention from researchers in recent years. Contrary to fragile systems which fail when exposed to stressors, antifragile systems prosper and improve in response to unpredictability, volatility, randomness, chaos and disturbance. The implications of antifragility goes beyond resilience or robustness. A resilient system resists stress and remains the same; while an antifragile system improves. Taleb argues that antifragility is required for dealing with events that he called black swans or X-events, which are scarce, unpredictable, and extreme events. Such events come as a surprise and have major consequences. The concept of antifragility was developed by Taleb in a socioeconomic context, not in industrial production. However, the authors think that this concept may have its greatest practical utilization when applied to industrial environments. Thus, they focused on this concept in the article aiming to investigate the level of antifragility in an organization. In order to perform this, the authors used a case study based on an Iranian manufacturer of banknotes and security paper (TAKAB). Firstly, a questionnaire was designed based on 7 criteria related to antifragility using the five-point Likert scale and a triangular fuzzy number for each linguistic term is defined. In the next phase, the weight of each component was obtained using the entropy technique. In the final stage, the Euclidean distance between the aggregated fuzzy antifragility index (FAI) and each linguistic term used during this case study was calculated. Finally, based on these results, the level of the organization’s antifragility was assessed as satisfactorily antifragile, based on the minimum Euclidean distance.

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Investigation of 99Mo potential production via UO2SO4 liquid target irradiation in a 5 MW nuclear research reactor

Gholamzadeh Z., Mirvakili S. M., Davari A., Alizadeh M., Joz-Vaziri A.

Nukleonika

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2017

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Vol. 62, No. 1

37--45

EN

The activation method for 99Mo production in comparison to fi ssionable target irradiation in research reactors is less preferable. Therefore, 99Mo yield using UO2SO4 samples was theoretically investigated. Computational results revealed admirable potential of the liquid samples for 99Mo production. Low-concentrated uranyl sulphate samples could easily be handled by the irradiation box. The sample geometry optimization improves thermal hydraulic conditions and production yield. The optimized geometry including only 0.12 g 235U produced 57Ci99Mo at end-of-irradiation (EOI) with a temperature peak of 72°C during the irradiation.

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Residence time distribution model of dual phase fluid flow in the mixer settler

Alizadeh M., Hosseinzadeh M.

Inżynieria Mineralna

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2013

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R. 14, nr 2

25--30

EN

In this study, the residence time distribution of the fluid stream in a mixer settler was simulated in order to achieve the optimal extraction time and the best performance. The aqueous and organic phases were water and kerosene, respectively; and the salt tracer changes were recording continuously by using a conductivity meter. Initially, experiments were performed at different mixing times in the phase ratio of 1:1. Then, results were analyzed applying Matlab software and Weller and N-Mixer models in RTDWEN software. Finally, for the mixing period of 5 min, the mean residence time was obtained 4.86 min by Matlab, and 6.44 and 6.62 min by RTDWEN, respectively for Weller and N-Mixer models. Furthermore, setting the mixing period at 5 min, the effect of mixer settler units was investigated by using N-Mixer model, and it was found that it was beneficial to increase the number of units, and set the residence time distribution close to extraction time at 6 min. It was also shown that under these conditions, the removed material from the mixer before the mean residence time was minimum, and both phases have an enough time for mixing and settling.

PL

W badaniu zasymulowano rozkład czasu przebywania strumienia płynu w osadniku w celu osiągnięcia optymalnego czasu ekstrakcji i najlepszej wydajności procesu. Fazami wodnymi i organicznymi były odpowiednio woda i nafta; zmiany wskaźnika kwasowości były rejestrowane w sposób ciągły dzięki użyciu konduktometru. Początkowo eksperymenty przeprowadzano przy różnych czasach mieszania przy stosunku faz 1:1. Następnie wyniki analizowano stosując środowisko programu Matlab oraz modele Weller i N-Mixer w programie RTDWEN. Finalnie, dla czasu mieszania wynoszącego 5 minut, otrzymano 4,86 min w programie Matlab oraz 6,44 i 6,62 min w programie RTDWEN odpowiednio dla modeli Weller i N-Mixer. Co więcej, po ustawieniu czasu mieszania na 5 min badano efekt jednostek osadnika przez użycie modelu N-Mixer i dowiedziono, że korzystne było zwiększenie liczby jednostek oraz nastawienie czasu rozkładu zbliżonego do czasu ekstrakcji wynoszącego 6 min. Pokazano również, że w tych warunkach materiał usunięty z mieszalnika zanim właściwy czas przebywania był minimalny, a obie fazy miały wystarczająco dużo czasu na mieszanie i osadzanie.