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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Prognostisering av produktionskapacitet - En studie på PET-Turbuhaler, AstraZeneca / Forecasting capacity of PET-Turbuhaler production at AstraZeneca

EINARSSON, JOHANNA, SÖDERLUND, HELENA January 2016 (has links)
En viktig aspekt för att få ett företag att bli så framgångsrikt som möjligt är att ha en träffsäker kapacitetsprognostisering av produktionen. En kapacitetsprognostisering hjälper ett företag att förutse och planera sin produktion för att kunna uppfylla den framtida efterfrågan. Därför är det av stor betydelse att prognostiseringen av kapaciteten är träffsäker. Detta är huvudområdet i denna examensrapport. Rapportens författare kom under vårterminen 2016 i kontakt med produktionsenheten PET-Turbuhaler på AstraZeneca i Södertälje. De efterfrågade en träffsäker modell för deras kapacitetsprognostisering på lång sikt, 12-24 månader. Examensarbetets syfte har därför sammanställts i en huvudfrågeställning som lyder; Vilket arbetssätt är det bästa för att PET-Turbuhaler ska uppnå en träffsäker produktionskapacitetsprognostisering på 12-24 månader? För att besvara frågeställningen genomfördes en förstudie, en litteraturstudie samt en intern och en extern benchmarking som alla analyserades och sammanställdes. Förstudien gav en övergripande bild av hur arbetet med den Microsoft Excel-modell som PET-Turbuhaler använder idag fungerar. Dessutom framkom vilka problem som de anställda ser att det finns med den nuvarande modellen. Författarna har även gjort egna analyser av PET-Turbuhalers kapacitetsmodell. Litteraturstudien som gjordes visar bland annat varför det är en skillnad mellan teoretisk och verklig kapacitet. För att beräkna den verkliga produktionskapaciteten behöver anläggningens schemalagda kapacitetsförluster (t.ex. lunch, möten), kapacitetsbortfall (t.ex. maskinhaveri, ställtid) och ej planerad verksamhet (t.ex. defekter) subtraheras från anläggningens teoretiska kapacitetstillgång, d.v.s. när anläggningen är igång dygnet runt, året om. Analysen visade att den modell som PET-Turbuhaler använder idag omfattar i stort sett samma parametrar som den modell litteraturen hänvisar till. Examensarbetarna insåg därför att PET-Turbuhalers problem med en bristande kapacitetsprognos på lång sikt inte nödvändigtvis ligger i den modell som används idag utan snarare i hur modellen används. Det har kommit upp till ytan att parametrar inom den nuvarande modellen inte uppdateras kontinuerligt med aktuell indata. Detta gör att gammal produktionsdata som är inaktuell ligger till grund för den kapacitetsprognos som görs på lång sikt. Frågeställningen kunde besvaras utifrån det underlag som tagits fram i analysen. Det mest intressanta resultatet blev att PET-Turbuhalers kapacitetsprognos på kort sikt inte är lika träffsäker som man tidigare trott. Följden av detta är att ett bra fungerande standardiserat arbete för den korta prognosen behöver utformas för att i framtiden få en träffsäkrare prognos på lång sikt. Efter diskussioner av resultatet kunde examensarbetarna slutligen komma fram till rekommendationer för hur PET-Turbuhaler bör fortsätta arbeta. Några av rekommendationerna är att utvärdera insamlad data kontinuerligt, ha regelbundna möten mellan produktionstekniker och gruppchefer samt att montera en sensor, som kan registrera output-takten, längst ner i flödet på produktionslinorna. / A company needs an accurate capacity plan to become successful. The capacity plan is an important tool for planning and anticipating production which is essential to be able to meet future demands. It is therefore of great importance to get an accurate forecasting of the production capacity, which is the main topic of this report. During the spring semester 2016, the authors of this report were contacted by the production unit PET-Turbuhaler at AstraZeneca in Södertälje. PET-Turbuhaler requested an accurate model for the long term, 12-24 months, forecasting of their production capacity. From this problem, a research question has been formulated into; Which is the best way for PET-Turbuhaler to work to reach an accurate long term, 12-24 months, production capacity prognosis? A pre-study, a literature study and an internal and an external benchmarking were conducted in order to answer the research question. The result from these were afterwards compiled and analyzed. The pre-study at PET-Turbuhaler gave an overview of the work with the current Microsoft Excel-model and its associated problems. The pre-study did also consist of the authors’ own analysis of PET-Turbuhalers capacity model. The literature study was made to investigate how theory advocates the work with capacity forecasting. It showed a difference between theoretical and real capacity. The real capacity is calculated by subtracting the plant’s scheduled and nonscheduled capacity losses (such as time losses for lunch, meetings, set-ups, machine breakdowns and defects from production) from the theoretical capacity. The theoretical capacity of the plant is the capacity when the plant runs 24 hours a day every day of the year. The analysis showed that the current model PET-Turbuhaler use today consist of more or less the same parameters as the literature suggests. The authors could therefore realize that the current model is not necessarily the main problem at this stage. The biggest problem is rather how the current model is being used by the employees. Parameters within the current model are not continuously updated with right data as PET-Turbuhaler thought. The consequence of this is that the long term forecasting is based on out-of-date data even though new and more accurate data is available. The research question can be answered based on the analysis. The most interesting result was the insight that the short term forecasting is not as accurate as PET-Turbuhaler believed. This gives, in order to achieve a good long term forecasting, that PET-Turbuhaler must first improve their short term forecasting by establishing a standardized way of working with the model. Only then can the long term forecasting be accurate. Through discussions regarding the result the authors were able to suggest improvements on how PET-Turbuhaler could work to reach an accurate long term forecast of their production capacity prognosis. The recommendations include continuous evaluation of collected data, regular meetings between production support and production line managers and the benefit of using a sensor, in the end of the production line, to registrate the output rate.
2

Teplotní závislost kapacity negativní elektrody pro sodno – iontové akumulátory / Temperature dependence of negative electrode capacity for sodium - ion batteries

Šátek, Dominik January 2021 (has links)
This work focuses on sodium-ion batteries. It describes the basic principles of accumulators, focusing more on secondary cells, their electrodes, especially negative electrodes. The work is lightly based on the basics of lithium-ion batteries. The practical part of the work is the production of negative electrodes Na2Ti3O7, which are further measured at three different temperatures. These measurements are then evaluated.
3

Mathematical modelling of primary alkaline batteries

Johansen, Jonathan Frederick January 2007 (has links)
Three mathematical models, two of primary alkaline battery cathode discharge, and one of primary alkaline battery discharge, are developed, presented, solved and investigated in this thesis. The primary aim of this work is to improve our understanding of the complex, interrelated and nonlinear processes that occur within primary alkaline batteries during discharge. We use perturbation techniques and Laplace transforms to analyse and simplify an existing model of primary alkaline battery cathode under galvanostatic discharge. The process highlights key phenomena, and removes those phenomena that have very little effect on discharge from the model. We find that electrolyte variation within Electrolytic Manganese Dioxide (EMD) particles is negligible, but proton diffusion within EMD crystals is important. The simplification process results in a significant reduction in the number of model equations, and greatly decreases the computational overhead of the numerical simulation software. In addition, the model results based on this simplified framework compare well with available experimental data. The second model of the primary alkaline battery cathode discharge simulates step potential electrochemical spectroscopy discharges, and is used to improve our understanding of the multi-reaction nature of the reduction of EMD. We find that a single-reaction framework is able to simulate multi-reaction behaviour through the use of a nonlinear ion-ion interaction term. The third model simulates the full primary alkaline battery system, and accounts for the precipitation of zinc oxide within the separator (and other regions), and subsequent internal short circuit through this phase. It was found that an internal short circuit is created at the beginning of discharge, and this self-discharge may be exacerbated by discharging the cell intermittently. We find that using a thicker separator paper is a very effective way of minimising self-discharge behaviour. The equations describing the three models are solved numerically in MATLABR, using three pieces of numerical simulation software. They provide a flexible and powerful set of primary alkaline battery discharge prediction tools, that leverage the simplified model framework, allowing them to be easily run on a desktop PC.

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