Analysis of the statistical methods in the company AFL Stříbro. Comparison to the VDA standard.

Biomassa är en växande energikälla i samhället. Biomassa så som sågspån behöver ofta torkas och pelleteras innan det kan användas som energikälla vid förbränning. Sågspån torkas innan pelleteringen för att kunna ge ett bra värmevärde och för att kunna förbrännas utan ökade halter av utsläpp. I takt med ökad användning av detta bränsle finns det en ökad efterfrågan på energieffektiva torkningsmetoder. På Karlstad Universitet har det därför byggts en pilotanläggning av en pneumatisk tork med syfte att fungera som ett steg i en energieffektiv torkningsmetod kallad ”Two Step Drying Technique” eller TSDT. Det här arbetet har handlat om att utvärdera effektivitetsmått och driftinformation för torken på Karlstads Universitet. Torken har fått namnet PD-KaU som står för ”Pneumatic Dryer at Karlstad University”. Genom praktiska mätningar av PD-KaU:s prestanda vid torkning av sågspån med uppvärmd luft har effektivitetsmåtten  och  beräknats vid olika driftfall. Även skillnader i torr- och våttemperaturer i olika delar av torken har utvärderats. En effektbalans har använts för att kontrollera mätningarnas stabilitet. De olika driftfallen fås genom variation av torkningsparametrar så som mängden sågspån som torkas, ca 1 och 2 kg torrsubstans per minut, och variation av luftens temperatur, 80, 100 och 120 °C, samt hastighet genom torken, 6, 8 och 10 m/s. Även 12 och 14 m/s testades vid 80 °C. Torkens minimala fluidiseringshastighet för sågspån har beräknats och minimala hastigheten som krävs för att sågspånet ska transporteras genom torkens rörsystem har mätts. Mätningar på sågspånets fukthalter före och efter torken tillsammans med massflöden sågspån genom torken har gjorts för alla driftfall. Använd effekt från överhettare och fläkt som finns i anslutning till torken har också mätts och dessa mätningar ligger till grund för beräkningarna av  och . Med hjälp av elektronisk mätning av torra temperaturer och tryckfall över systemet har också våttemperaturer i olika delar av systemet kunnat beräknas. All data från dessa mätningar har också använts till effektbalansen. Vid massflöden på ca 1 kg/min TS sågspån genom torken är  som högst om hastigheten på luften är låg. Högsta  för de driftfall som testats vid detta massflöde fås när lufttemperaturen är 120 °C och lufthastigheten är kring 8,6 m/s. Genom öka på rörsystemets längd i torken skulle ett högre  kunna uppnås vid högre hastigheter. Vid ett massflöde på ca 2 kg/min fås högsta  vid lufttemperaturen 100 °C och lufthastighet kring 8,3 m/s. Om höga massflöden sågspån används kommer sågspånet i större grad i kontakt med luften och  är högt oberoende av lufthastigheten i de intervall som testats. Optimala lufttemperaturen visade sig vara vid 100 °C.  är som lägst vid låga hastigheter och höga massflöden. Lägsta värdet på  för båda massflödena fås när lufttemperaturen var 120 °C och lufthastigheten 7,0 m/s. Genom att minska på rörsystemets längd skulle  kunna minska. Utvärderingen av våttemperaturen visar att det mesta av torkningen sker i början av systemet. / Biomass is a growing source of energy in our society. Biomass such as sawdust often needs to be dried and pelletized before it can be burnt to produce energy. Sawdust is dried before pelleting in order to give a good calorific heat value and to be able to be incinerated without increased levels of emissions. With increased use of this fuel there is an increasing demand for energy efficient drying methods. A pilot plant of a pneumatic dryer has therefore been built at Karlstad University with a purpose to serve as a step in an energy efficient drying method called “Two Step Drying Technique” or TSDT. This thesis aimed to evaluate performance and operating information for the dryer at Karlstad University. The dryer has been named PD-KaU which stands for "Pneumatic Dryer at Karlstad University." Through practical measurements of the PD-KaU's performance when drying sawdust with heated air, efficiency indices  and  has been calculated at various operating conditions. Differences in the dry and wet-bulb temperature in different parts of the dryer have also been evaluated. An energy balance, or more correctly a power balance has been used to evaluate the stability of the measurements. The various operating conditions is obtained by variation of different drying parameters such as the amount of sawdust dried, about 1 and 2 kg solids per minute, and the variation of air temperature, 80, 100 and 120 ° C, and the speed through the dryer, 6, 8 and 10 m/s. Also, 12 and 14 m/s were tested at 80 ° C. The minimum fluidizing velocity for the dryer when using sawdust has been calculated and the minimum speed required for the transportation of sawdust through the dryer tubes have been measured. Measurements on the sawdust moisture levels before and after the dryer along with the mass flow of sawdust through the dryer have been made for all operating conditions. The power from the super heater and fan that is used with the dryer has also been measured and these measurements together with the moisture levels and mass flows are used for calculating  and. By using electronic equipment measurements of dry temperatures and pressure drop across the system has also been possible and they have been used to calculate the wet-bulb temperature in different parts of the system. All data from these measurements were also used for the power balance. At mass flow rates of about 1 kg/min solids of sawdust through the dryer  is highest if the speed of the air is low. The highest value on  for the various operating conditions at this mass flow rate was found to be at an air temperature of 120 °C and air speed of 8,6 m/s. By increasing the length of tubing in the dryer, a higher  be achieved at higher speeds. If 2 kg/min of solids are put into the system the sawdust comes in contact with the air to a greater extent and  is highly independent of the air velocity in the ranges tested. At this higher mass flow rate the highest value of  was found to be at an air temperature of 100 °C and an air speed of 8,3 m/s Optimum air temperature was found to be at 100° C.  is lowest at low speeds and high mass flows. The lowest value for  for both tested mass flow rates was found to be when the air temperature was 120 °C and the air speed was 7,0 m/s. By reducing the tubing length SPC could be reduced. The evaluation of the wet-bulb temperature shows that most of the drying takes place in the beginning of the system.

Master of Science / Department of Industrial & Manufacturing Systems Engineering / John R. English / Inventory accuracy is critical for almost all industrial environments such as distribution, warehousing, and retail. It is quite common for companies with exceptional inventory accuracy to use a technique called cycle counting. For many organizations, the time and resources to complete cycle counting are limited or not available. In this work, we promote statistical process control (SPC) to monitor inventory accuracy. Specifically, we model the complex underlying environments with mixture distributions to demonstrate sampling from a mixed but stationary process. For our particular application, we concern ourselves with data that result from inventory adjustments at the stock keeping unit (SKU) level when a given SKU is found to be inaccurate. We provide estimates of both the Type I and Type II errors when a classic c chart is used. In these estimations, we use both analytical as well as simulation results, and the findings demonstrate the environments that might be conducive for SPC approaches.

No description available.

In this thesis study, fabrication and characterization of silicon thin films prepared by magnetron sputtering and electron beam evaporation for solar cell applications have been investigated. In the first part of the study, magnetron sputtering method was used to fabricate thin hydrogenated amorphous silicon (a-Si:H) film on a Si substrate. Some samples were prepared on glass substrate for the basic characterizations like transmission and resistivity. Dark and illuminated I-V characteristics of the silicon heterojunction (SHJ) solar cells were studied as a function of material type and process parameters. It was observed that devices show diode characteristics, however their response to the illumination was quite weak. Low performance of the devices was discussed in terms of the resistivity and dopability of the sputtered film. The second part of the thesis deals with the fabrication and characterization of thin polysilicon films fabricated by e-beam evaporation. In order to dope the deposited Si films, a very thin boron film v was deposited by e-beam evaporation on SiO2 surface thermally grown on a Si wafer. Then an a-Si was evaporated by the same technique. Samples were annealed for polysilicon formation by using the technique called solid phase crystallization (SPC). The annealing was performed in two steps. The first step was the nucleation part, carried out at 475&deg / C for 8 hours and the second step was the diffusion and crystallization parts that are accomplished at 900&deg / C for several minutes. The Raman measurements revealed out the crystallinity and grain size. The crystallinity of the polysilicon thin films was also identified by X-Ray diffraction measurements. Finally, the Secondary Ion Mass Spectroscopy (SIMS) analysis was carried out to find out the amount of boron that diffuses into Si film. It was found that a graded boron profile, which is desirable for the solar cell applications, was achieved.

In this study, a tool is developed for determining priorities of quality improvement activities for manufacturing operations, for the purposes of both quality and throughput improvement. This tool utilizes Quality Function Deployment (QFD), Theory of Constraints (TOC), Statistical Process Control (SPC) and Failure Mode and Effects Analysis (FMEA) methodologies. The use of the tool is demonstrated on an example problem. The results obtained under different experimental conditions are compared with solutions of more popular, simple decision-making measures, and the optimal solutions obtained from a mathematical model. The analysis shows that the proposed tool gives close solutions to optimal, and it can easily be applied in a typical manufacturing setting. This study also demonstrates how various different methodologies can be integrated for the purposes of quality and throughput improvement in shorter times.

Master of Science / Department of Industrial & Manufacturing Systems Engineering / John English / This research builds upon previous efforts to explore the use of Statistical Process Control (SPC) in lieu of cycle counting. Specifically a three pronged effort is developed. First, in the work of Huschka (2009) and Miller (2008), a mixture distribution is proposed to model the complexities of multiple Stock Keeping Units (SKU) within an operating department. We have gained access to data set from a large retailer and have analyzed the data in an effort to validate the core models. Secondly, we develop a recursive relationship that enables large samples of SKUs to be evaluated with appropriately with the SPC approach. Finally, we present a comprehensive set of type I and type II error rates for the SPC approach to inventory accuracy monitoring.

A cultura da cana-de-açúcar no Brasil teve na safra 2007/2008 um aumento de 7,4% na área de plantio, sendo o estado e São Paulo responsável por 67% deste aumento. Estabelecer estas expansões ou reformas de canaviais com qualidade se torna imprescindível, pois a cana é uma gramínea perene com ciclo de quatro a cinco anos. Uma das alternativas para melhorar esta qualidade é a utilização de ferramentas como o controle estatístico do processo (CEP) que vem apresentando bons resultados nesta busca. Devido a importância da cultura da cana-de-açúcar, o aumento considerável no plantio da cultura e a exigência pela qualidade no setor, o objetivo deste trabalho foi identificar os fatores críticos e analisar o processo de melhoria continua no plantio da cana-de-açúcar. O trabalho foi desenvolvido na usina Pioneiros Bioenergia S.A e contou com o apoio da equipe técnica da usina. Na primeira etapa selecionaram-se as principais falhas do plantio, que posteriormente foram classificadas de acordo com a severidade, facilidade de ocorrência e de detecção. Em seguida definiram-se seus respectivos indicadores críticos, sendo eles o paralelismo, a profundidade de sulco, número de gemas viáveis por metro e altura de cobrição. Na segunda etapa se utilizaram histogramas, gráficos de controle e Pareto para avaliar a qualidade operacional no plantio, que se mostrou com grande instabilidade e variabilidade. Elaborou-se então, um conjunto de ações para diminuir esta instabilidade, denominado de plano de melhorias. Com a implantação deste plano deu-se inicio a etapa três, onde se avaliou novamente os indicadores considerados insatisfatórios. O paralelismo e a profundidade de sulco apresentaram um aumento dos dados dentro das especificações técnicas, porém, a altura de cobrição sofreu influência da época seca desfavorável para esta operação, proporcionando um aumento da terra na cobrição das mudas. Elaborou-se novamente, um segundo plano de melhorias e para isso utilizaram-se as informações dos gráficos de Pareto. Concluiu-se que a etapa dois apresentou-se com grande instabilidade e fora dos padrões estabelecidos. Com a implantação do plano de melhorias, etapa três, estes se mostraram com melhor estabilidade e com mais dados dentro das especificações. A utilização das ferramentas do CEP e do gráfico de Pareto se mostrou de grande valor na diminuição da instabilidade e melhoria dos processos, bem como na elaboração de um segundo plano de melhorias. / The sugar cane cultivation in Brazil, during the 2007/2008 period, showed a planting area increase of 7.4%. Sao Paulo state was responsible for 67% of this increase. It is vital to conduct those sugar cane plantation expansions and renovations with high quality, because sugar cane is a perennial grass, with a cycle of four to five years. A good alternative to improve plantation expansion and renovation process is the use of Statistical Process Control (SPC). The application of this tool has showed good results. Taking into consideration the great importance of sugar cane cultivation, the increase of sugar cane cultivation area and demand for higher quality, the purpose of this project is to identify critical factors and study the continuous improvement of sugar cane planting process. This project was developed in Pioneiros Bioenergia S.A. sugar mill and had the support of plant technical staff. In the first phase, the main planting failures were selected and classified by severity, occurrence probability and detection easiness. The critical parameters of the selected failures were also defined: furrow parallelism, furrow depth, number of good gemmas per meter and soil covering height. In the second phase histograms, control graphs and Paretto charts were used to evaluate planting operational quality, which showed high instability and variability. An action plan was then developed to reduce that instability, named Improvement Plan. The third phase started with improvement plan implementation, including reevaluation of critical parameters. There was an improvement of furrow parallelism and an increase of furrow depth values in accordance with specifications, but soil covering height was negatively influenced by dry season, which makes covering soil excess more likely to occur. A second Improvement Plan was developed, using Paretto chart information. It was concluded that the instability and values outside the established pattern observed in phase two were reduced by the implementation of the improvement plans carried out during phase three, which has shown better stability and more values in accordance with specifications. The application of SPC tools and Paretto charts was very useful in the process of obtaining planting process stability improvement, including the development of a second Improvement Plan.

A cultura da cana-de-açúcar no Brasil teve na safra 2007/2008 um aumento de 7,4% na área de plantio, sendo o estado e São Paulo responsável por 67% deste aumento. Estabelecer estas expansões ou reformas de canaviais com qualidade se torna imprescindível, pois a cana é uma gramínea perene com ciclo de quatro a cinco anos. Uma das alternativas para melhorar esta qualidade é a utilização de ferramentas como o controle estatístico do processo (CEP) que vem apresentando bons resultados nesta busca. Devido a importância da cultura da cana-de-açúcar, o aumento considerável no plantio da cultura e a exigência pela qualidade no setor, o objetivo deste trabalho foi identificar os fatores críticos e analisar o processo de melhoria continua no plantio da cana-de-açúcar. O trabalho foi desenvolvido na usina Pioneiros Bioenergia S.A e contou com o apoio da equipe técnica da usina. Na primeira etapa selecionaram-se as principais falhas do plantio, que posteriormente foram classificadas de acordo com a severidade, facilidade de ocorrência e de detecção. Em seguida definiram-se seus respectivos indicadores críticos, sendo eles o paralelismo, a profundidade de sulco, número de gemas viáveis por metro e altura de cobrição. Na segunda etapa se utilizaram histogramas, gráficos de controle e Pareto para avaliar a qualidade operacional no plantio, que se mostrou com grande instabilidade e variabilidade. Elaborou-se então, um conjunto de ações para diminuir esta instabilidade, denominado de plano de melhorias. Com a implantação deste plano deu-se inicio a etapa três, onde se avaliou novamente os indicadores considerados insatisfatórios. O paralelismo e a profundidade de sulco apresentaram um aumento dos dados dentro das especificações técnicas, porém, a altura de cobrição sofreu influência da época seca desfavorável para esta operação, proporcionando um aumento da terra na cobrição das mudas. Elaborou-se novamente, um segundo plano de melhorias e para isso utilizaram-se as informações dos gráficos de Pareto. Concluiu-se que a etapa dois apresentou-se com grande instabilidade e fora dos padrões estabelecidos. Com a implantação do plano de melhorias, etapa três, estes se mostraram com melhor estabilidade e com mais dados dentro das especificações. A utilização das ferramentas do CEP e do gráfico de Pareto se mostrou de grande valor na diminuição da instabilidade e melhoria dos processos, bem como na elaboração de um segundo plano de melhorias. / The sugar cane cultivation in Brazil, during the 2007/2008 period, showed a planting area increase of 7.4%. Sao Paulo state was responsible for 67% of this increase. It is vital to conduct those sugar cane plantation expansions and renovations with high quality, because sugar cane is a perennial grass, with a cycle of four to five years. A good alternative to improve plantation expansion and renovation process is the use of Statistical Process Control (SPC). The application of this tool has showed good results. Taking into consideration the great importance of sugar cane cultivation, the increase of sugar cane cultivation area and demand for higher quality, the purpose of this project is to identify critical factors and study the continuous improvement of sugar cane planting process. This project was developed in Pioneiros Bioenergia S.A. sugar mill and had the support of plant technical staff. In the first phase, the main planting failures were selected and classified by severity, occurrence probability and detection easiness. The critical parameters of the selected failures were also defined: furrow parallelism, furrow depth, number of good gemmas per meter and soil covering height. In the second phase histograms, control graphs and Paretto charts were used to evaluate planting operational quality, which showed high instability and variability. An action plan was then developed to reduce that instability, named Improvement Plan. The third phase started with improvement plan implementation, including reevaluation of critical parameters. There was an improvement of furrow parallelism and an increase of furrow depth values in accordance with specifications, but soil covering height was negatively influenced by dry season, which makes covering soil excess more likely to occur. A second Improvement Plan was developed, using Paretto chart information. It was concluded that the instability and values outside the established pattern observed in phase two were reduced by the implementation of the improvement plans carried out during phase three, which has shown better stability and more values in accordance with specifications. The application of SPC tools and Paretto charts was very useful in the process of obtaining planting process stability improvement, including the development of a second Improvement Plan.

This study attempts to trace the development of the Australian Capital Territory Secondary Principals' Council (SPC) from the midfifties to the late seventies. The dramatic change from the monolithic centralised New South Wales state education system to one of autonomous school-based decision making of the new ACT School Authority forms the background on which this study is developed. The changing fortunes of the SPC as a pressure group are followed from their prestigious days with the NSW school inspector to the depths of the conflicts of the early seventies when change towards autonomy was imminent. The Teachers' Federation, at this time, gained power at the expense of the SPC when the union demanded that it be the sole spokesman for ACT teachers. The multiplicity of problems confronting the SPC in the late sixties and early seventies resulted in the forming of the Preservation of Principals Society (POPS), which conducted certain activities to allow principals to get away from such pressures. The gradual gaining of acceptance, within this new task environment, by the SPC saw it become an expert unit within this participative model. SPC members are on many committees which function to improve the administration, the curricula, and other major facets of ACT education. Finally, this study culminates in the SPC formulating a set of goals to guide its operations in the future. Tentative recommendations for Council to consider form a conclusion. These are to: 1. convince the ACT Legislative Assembly that the SPC is an expert body which should be heeded when the Assembly assumes control of local education, and 2. act as a group to monitor the curricula of their schools to ensure that a relevant education is available for the next generation. Principals should initiate change for the future rather than react to the problems of the past.