Background and Objectives The management of platelet concentrate (PC) stocks is not simple given their short shelf life and variable demand. In general, managers decide on PC production based on personal experience. The objective of this study was to provide a tool to help decide how many PC units to produce each day in a more rational and objective way.
Materials and MethodsFrom the historical data on PCs produced, transfused and discarded in the Basque Country in 2012, a mathematical model was built, based on the normality of the time series of the transfusions performed on each day of the week throughout the year. This model was implemented in an easy-to-use Excel spreadsheet and validated using real production data from 2013.Results Comparing with real 2013 data, in the best scenario, the number of PC units that expired was 87Á7% lower, PC production, 14Á3% lower and the age of the PCs transfused nearly 1-day younger in the simulation. If we want to ensure a minimum stock at the end of each day, the outdating rate and average age of the transfused PCs progressively increase.
ConclusionThe practical application of the designed tool can facilitate decisionmaking about how many PC units to produce each day, resulting in very significant reductions in PC production and wastage and corresponding cost savings, together with an almost 1 day decrease in the mean age of PCs transfused.
Background and Objectives
Applying pathogen reduction technologies (PRT) to platelets can extend their shelf life from 5 to 7 days, but there have been few systematic studies of the repercussions of such technologies on outdate rates.
Material and Methods
The benefits in terms of outdate rates of applying PRT to platelets are studied via a mathematical simulation. Specifically, statistical methods are used to determine the daily production rate needed to meet demand while not exceeding a maximum amount set as a result of limitations on donations and while assuring a minimum daily stock.
Results
The results show that a 2‐day extension in the shelf life of platelet concentrates (PC) results in reductions in outdates ranging from 88·4% to 100% at the production centres analysed. It may be the case for budgetary reasons that only part of the PCs produced can be treated. This being so, we show that if the proportion treated per annum exceeds 25% the best option is to treat part of the output every day, otherwise, it is preferable to concentrate treatment on the last two production days of the week.
Conclusions
Extending the shelf life of PC from five to seven days and setting up suitable production logistics can drastically reduce outdates at production centres. If only a part of all PCs is treated, the best choices are to distribute PRT overall production days or, if the percentage of PCs treated is very low, to apply PRT on the days preceding the weekend break.
This paper presents a case study commissioned by the Spanish railway carrier Ferrocariles Españoles de Vía Estrecha for the annual rostering of work schedules for station personnel. A mixed rostering process is used. The first part of the process is carried out manually with the aid of a spreadsheet and Visual Basic, and consists of designing an initial graphic with 4-week patterns for each station, assigning those patterns in a rotating schedule over the year and factoring in vacation time. The second part consists of assigning relief shifts to cover those shifts left vacant in such a way as to minimize the distance travelled by personnel from other stations brought in for relief shift duty. To that end, basic programmes are designed using binary programming and a 4-week time frame. The results obtained are a clear improvement on the system previously used at FEVE and the company has decided to implement the model.
SUMMARYWe solve by a finite difference method a system of simultaneous non-linear partial differential equations which modelizes the transfer of heat and mass when a fluid evaporates from the hot wall and condenses on the cold wall of an upright rectangular cavity. The need to verify a certain condition associating the physical parameters of the fluid for the existence of steady state solutions is proved.
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