<p>Since a few years, flat screen TVs, such as LCD and plasma, has come to completelydominate the market of televisions. In a SoC solution for digital TVs, severalprocessors are used to obtain a decent image quality. Some of the processorsneed temporal information, which means that whole frames need to be storedin memory, which in turn motivates the use of SDRAM memory. When higherdemands of resolution and image quality arrives, greater pressure is put on theperformance of the SoC memory subsystem, to not become a bottleneck of thesystem.</p><p>In this master thesis project, a model of an existing SoC for digital TVs is usedto benchmark and evaluate the performance of an SDRAM memory controllerarchitecture study. The two major features are the ability to reorder transactionsand the compatibility with DDR3. By introducing reordering of transactions, thechoice is given to the memory controller to service memory requests in an orderthat decreases bank conflicts and read/write turn arounds. Measurements showthat a utilization of 86.5 % of the total available bandwidth can be achieved, whichis 18.5 percentage points more, compared to an existing nonreordering memorycontroller developed by NXP.</p>

Since a few years, flat screen TVs, such as LCD and plasma, has come to completelydominate the market of televisions. In a SoC solution for digital TVs, severalprocessors are used to obtain a decent image quality. Some of the processorsneed temporal information, which means that whole frames need to be storedin memory, which in turn motivates the use of SDRAM memory. When higherdemands of resolution and image quality arrives, greater pressure is put on theperformance of the SoC memory subsystem, to not become a bottleneck of thesystem. In this master thesis project, a model of an existing SoC for digital TVs is usedto benchmark and evaluate the performance of an SDRAM memory controllerarchitecture study. The two major features are the ability to reorder transactionsand the compatibility with DDR3. By introducing reordering of transactions, thechoice is given to the memory controller to service memory requests in an orderthat decreases bank conflicts and read/write turn arounds. Measurements showthat a utilization of 86.5 % of the total available bandwidth can be achieved, whichis 18.5 percentage points more, compared to an existing nonreordering memorycontroller developed by NXP.

The major objective of present study is to find out the sources which cause higher Work in Process (WIP) in the production line. In which a detailed analysis is performed in the area of inventory, reorder point, Takt time, and Kanban. All the analyses are based on the data obtained from the company’s ERP system and have been used to run some scenarios during the analysis.Lots of problems are responsible to cause higher WIP. But current report only focuses and concentrates in leveling the work load, implementing pull system, suggesting reorder point and Takt time.The current situation is described through Value-stream Map (VSM) and the impact cost matrix is used to show the impact of each problem in the production line in terms of costs. In the analysis chapter, root cause method has been used in order to show the cause and effect of higher WIP. Detailed analyses together with explanations are listed by orders. Therefore, three major suggestions are proposed and the future VSM is plotted to show the effect and change of the suggestions which helps to improve the current situation by eliminating the waste.

With growing markets and customers being geographically spread out, more pressure is put on a company’s logistics processes and their inventory structures are becoming more complex. This puts more pressure on the inventory control solution provided by a company like IFS, that supports their customers with inventory control through the Inventory Planning and Replenishment module in IFS Applications. As their customers’ supply chains grow larger, their inventory structures become more complex the next step is to find a solution for the IPR module more suitable in a called multi-echelon structure, i.e. several tiers of stock locations, such as local, regional and central warehouses.   The purpose of this study is to compare a reorder point model with a solution suitable in a multi-echelon setting and investigate how they are able to manage uncertainties with service level targets.   A literature study was performed, to find previous research on inventory control in multi-echelon inventory systems. In the literature study, the importance of coordination and information sharing between the echelons was emphasized and used as a focus when finding a suitable multi-echelon model. To answer the purpose a theoretical model was formulated from the findings in previous research, with a replenishment method suitable in a multi-echelon environment. The inventory control models also included lot sizing method and a safety mechanism, where the difference between the models were their respective replenishment policy. The theoretical model was based on the replenishment method Distribution Requirements Planning (DRP), as it enables information sharing, coordination and synchronization of the supply chain, while the other inventory control model uses the Reorder Point method (ROP).   As information sharing was emphasized in previous research on multi-echelon systems, and the main difference between the two inventory control models is the information sharing in the DRP model, the important question to be answered with the comparison is; what effects and benefits can be achieved through information sharing in a multi-echelon inventory system? The two inventory control models were then simulated in Excel and exposed to even demand and seasonal variations in an inventory structure with three echelons and four sites, see figure below. When analyzing the results three evaluation criteria were used; difference in service levels, average inventory levels and if there were signs of overstocking in the regional and central warehouse, i.e. if the system was exposed to the bullwhip effect.   The analysis was carried out based on the criteria above and divided into three sections. First, differences between the models for even demand were investigated. The same procedure followed for seasonal demand, identifying differences and what caused them. Findings were then summed up at the end of the chapter. For even demand, differences were small and sharing information does not give large benefits. Under seasonal demand though, sharing information proved to be very beneficial, reducing average inventory held in the system by 60%, compared to not sharing information. This because sharing information together with synchronizing eliminates the bullwhip effect.   By testing different standard deviations, changing lead times and order quantities, using forecast or being blind to forecast, the robustness of the conclusions drawn from the analysis was put to the test. Carrying out a sensitivity analysis on the models served two purposes. First, finding more evidence promoting the benefits of synchronizing the supply chain and how important it is that the shared information is correct, otherwise the benefits are reduced. The second purpose was to validate that the models performed as expected when changing input data.   The conclusions were the following:   Information sharing enables synchronization of the supply chain Synchronization allows for reaching higher service levels with lower inventory levels   Findings suggest that by sharing information, which must be the first step, synchronizing the inventory system is possible. It is the synchronization that creates the real benefits, such as higher service levels and lower inventory levels. However, the quality and accuracy of the shared information was found to play an important role. Sharing inaccurate or wrong information increase the risk of the system starting to suffer from the bullwhip effect, resulting in higher inventory levels and lower service levels.

Bakgrund: För företag som håller lager är en viktig faktor för att lyckas öka effektiviteten att arbeta med lagerstyrning. Lagerstyrning handlar om planering och kontroll av lagret för att kunna serva kunderna och produktionen. Inom lagerstyrning är det viktigt att företag fattar beslut gällande vilken orderkvantitet som ska beställas samt när ordern ska läggas för att finnas tillgänglig på lagret vid rätt tidpunkt. Företag kan använda sig av säkerhetslager vid styrning av sitt lager för att försäkra sig om att de kan hantera osäkerheter i efterfrågan och produktion. Syfte: Syftet med studien är att utifrån analys av lagerstyrningsteori utforma en teoretisk lagerstyrningsmodell för att skapa förståelse för hur lageromsättningshastigheten kan öka. Vidare ska den framtagna modellen empiriskt appliceras på Sandviks produktionsavdelning i Svedalas aktuella artiklar för att identifiera möjliga förbättringar. Metod: Studien har genomförts som en fallstudie på Sandviks produktionsavdelning i Svedala baserat på en teoretisk framtagen lagerstyrningsmodell. Teoriinsamlingen till utformandet av den teoretiska lagerstyrningsmodellen har inhämtats via facklitteratur och vetenskapliga artiklar. Empiriinsamlingen har gjorts med hjälp av intervjuer och numerisk data. Både teori och empiri har sedan analyserats utifrån ett kvalitativt tillvägagångssätt. Avslutande kommentarer: Den framtagna teoretiska lagerstyrningsmodellen börjar med att presentera kriterier som påverkar lageromsättningshastigheten, sedan presenteras steg för att genomföra en ABC-klassificering och slutligen presenteras olika lagerstyrningsmetoder för att bestämma hur orderläggningen ska ske samt hur stortivsäkerhetslagret ska vara. Den teoretiska lagerstyrningsmodellen är pedagogisk och tydlig för att skapa förståelse hos företag om hur de kan öka sin lageromsättningshastighet. Lagerstyrningen som formades utifrån den teoretiska lagerstyrningsmodellen för Sandviks produktionsavdelning i Svedala bestod av orderläggningsmetoderna lot-for-lot, uppskattad orderkvantitet och täcktidplanering samt säkerhetslager baserat på manuella bedömningar och baserat på ledtidsförbrukningen. Med hjälp av denna lagerstyrning ska de proaktivt undvika föråldrat och långsamtgående lager i framtiden. / Background: In order to increase the efficiency for companies that keep inventory, they need to work with inventory control. Inventory control regards planning and control of the inventory to increase customer and production service. Within inventory control, it is important that companies make decisions regarding the quantity to be ordered and when the order will be added to be available in the warehouse at the right time. Companies can use safety stock to ensure that they can deal with uncertainties in demand and production. Purpose: The purpose of this study is, based on analysis of inventory control theory, to design a theoretical model of inventory control to create an understanding for how the inventory turnover may increase. Furthermore, the theoretical model will be empirically applied to Sandvik's production department of Svedala's current articles to indicate improvements. Method: The study has been made as a case study at Sandvik´s production department in Svedala, based on a developed theoretical model of inventory control. Theory collection to the design of the theoretical model of inventory control has been obtained through professional literature and scientific articles. Empirical data has been collected through interviews and numerical data. Both theory and empirical data have been analyzed from a qualitative approach. Concluding remarks: The designed theoretical model of inventory includes criteria that affect inventory turnover, the steps to implement an ABC classification and various inventory control methods to determine how the placement of orders should be implemented and the amount of safety stock that should be held. The theoretical model vi of inventory control is pedagogical and clear to create an understanding regarding how companies can increase their inventory turnover. The inventory control that was formed for Sandvik´s production department in Svedala, on the basis of the theoretical model of inventory control, consisted of the ordering methods, lot-for-lot, estimated order quantity and cover-time planning. The methods for safety stock were safety stock based on manual assessments and on lead time consumptions. With this control Sandvik´s production department in Svedala, proactively can avoid obsolete and slow moving inventory in the future

O trabalho a seguir apresenta o desenvolvimento e resultados da pesquisa acerca de modelos de estoques para múltiplos fornecedores, baseado na distribuição de peças de manutenção de empresas de tecnologia no Brasil. Em função de características de demandas erráticas, altos custos das peças e demanda por tempos de entrega reduzidos, costuma-se adotar uma estratégia de distribuir peças em diversos centros de estoques por todo território nacional. Entretanto, manter altos estoques em cada uma das localidades do sistema pode trazer custos elevados. Devido às características da demanda, muitas vezes ocorrem faltas de estoques de itens críticos, que são enviados aos locais de demanda por meio de transportes emergenciais de alto custo e prazos de entregas reduzidos. Entretanto, os modelos convencionais de estoques adotados, não consideram as possibilidades de envios emergenciais em suas formulações, fazendo desta solução uma situação não prevista na modelagem e potencialmente não ótima. A presente pesquisa tem por objetivo desenvolver e avaliar os modelos convencionais de estoques para a situação de múltiplos fornecedores considerando custos e prazos de entregas diferentes, como alternativa para os modelos adotados na distribuição de peças de manutenção. Sua aplicação a outros problemas, inclusive ambientes de múltiplos fornecedores independentemente de diferenças de transportes é imediata. A pesquisa abrange sete modelos, sendo três modelos reativos (reposição da base, reposição do máximo e lote fixo) em regimes de revisão periódica e contínua, e um modelo ativo considerando previsão de demanda. Foi utilizada busca local com simulação de eventos discretos para resolver os modelos propostos. / The present work presents research and development of multiple supplier inventory models, based on the service parts logistics in the technology industry. Because of the lumpy demand characteristics, high costs of parts and low delivery time expectations, a strategy to spread parts inventories all over the country was adopted. However, maintaining high inventory in every location of the system can lead to high costs. Because of the demand characteristics critical items can get unavailable in certain location, which are supplied by emergency shipment from supplying locations with high transportation costs and reduced delivery times. However, the conventional inventory models that are used do not consider the possibility of emergency shipments, leading to potential non optimal distribution of parts. The present research aims to develop and evaluate the inventory models considering multiple transportation modals with different lead times and costs, to serve as an alternative to the current inventory models used. The application to other problems, including different suppliers independent of transportation mode, is immediate. The research covers seven different models: three reactive, (s, S), (S-1, S) and (R, Q) in continuous and periodic review, and one demand prediction based model. Local search and discrete events simulation was used to resolve the models.

O trabalho a seguir apresenta o desenvolvimento e resultados da pesquisa acerca de modelos de estoques para múltiplos fornecedores, baseado na distribuição de peças de manutenção de empresas de tecnologia no Brasil. Em função de características de demandas erráticas, altos custos das peças e demanda por tempos de entrega reduzidos, costuma-se adotar uma estratégia de distribuir peças em diversos centros de estoques por todo território nacional. Entretanto, manter altos estoques em cada uma das localidades do sistema pode trazer custos elevados. Devido às características da demanda, muitas vezes ocorrem faltas de estoques de itens críticos, que são enviados aos locais de demanda por meio de transportes emergenciais de alto custo e prazos de entregas reduzidos. Entretanto, os modelos convencionais de estoques adotados, não consideram as possibilidades de envios emergenciais em suas formulações, fazendo desta solução uma situação não prevista na modelagem e potencialmente não ótima. A presente pesquisa tem por objetivo desenvolver e avaliar os modelos convencionais de estoques para a situação de múltiplos fornecedores considerando custos e prazos de entregas diferentes, como alternativa para os modelos adotados na distribuição de peças de manutenção. Sua aplicação a outros problemas, inclusive ambientes de múltiplos fornecedores independentemente de diferenças de transportes é imediata. A pesquisa abrange sete modelos, sendo três modelos reativos (reposição da base, reposição do máximo e lote fixo) em regimes de revisão periódica e contínua, e um modelo ativo considerando previsão de demanda. Foi utilizada busca local com simulação de eventos discretos para resolver os modelos propostos. / The present work presents research and development of multiple supplier inventory models, based on the service parts logistics in the technology industry. Because of the lumpy demand characteristics, high costs of parts and low delivery time expectations, a strategy to spread parts inventories all over the country was adopted. However, maintaining high inventory in every location of the system can lead to high costs. Because of the demand characteristics critical items can get unavailable in certain location, which are supplied by emergency shipment from supplying locations with high transportation costs and reduced delivery times. However, the conventional inventory models that are used do not consider the possibility of emergency shipments, leading to potential non optimal distribution of parts. The present research aims to develop and evaluate the inventory models considering multiple transportation modals with different lead times and costs, to serve as an alternative to the current inventory models used. The application to other problems, including different suppliers independent of transportation mode, is immediate. The research covers seven different models: three reactive, (s, S), (S-1, S) and (R, Q) in continuous and periodic review, and one demand prediction based model. Local search and discrete events simulation was used to resolve the models.

Los procesadores superescalares actuales utilizan un reorder buffer (ROB) para contabilizar las instrucciones en vuelo. El ROB se implementa como una cola FIFO first in first out en la que las instrucciones se insertan en orden de programa después de ser decodificadas, y de la que se extraen también en orden de programa en la etapa commit. El uso de esta estructura proporciona un soporte simple para la especulación, las excepciones precisas y la reclamación de registros. Sin embargo, el hecho de retirar instrucciones en orden puede degradar las prestaciones si una operación de alta latencia está bloqueando la cabecera del ROB. Varias propuestas se han publicado atacando este problema. La mayoría utiliza retirada de instrucciones fuera de orden de forma especulativa, requiriendo almacenar puntos de recuperación (checkpoints) para restaurar un estado válido del procesador ante un fallo de especulación. Normalmente, los checkpoints necesitan implementarse con estructuras hardware costosas, y además requieren un crecimiento de otras estructuras del procesador, lo cual a su vez puede impactar en el tiempo de ciclo de reloj. Este problema afecta a muchos tipos de procesadores actuales, independientemente del número de hilos hardware (threads) y del número de núcleos de cómputo (cores) que incluyan. Esta tesis abarca el estudio de la retirada no especulativa de instrucciones fuera de orden en procesadores superescalares, multithread y multicore. / Ubal Tena, R. (2010). Out-of-Order Retirement of Instructions in Superscalar, Multithreaded, and Multicore Processors [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8535 / Palancia

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