Background: Inventory control is a complex challenge that affects various activities on howinventory is controlled and managed. The management of inventory has a major impact on acompany's profitability and needs to be handled in different ways depending on the situationthe company is operating in. In order to improve operational inventory management forcompanies that have customer-unique products, high inventory availability and the desire forincreased inventory turnover rate, different aspects need to be addressed. Different items in acompany's assortment have different properties, and in order to control items in a goodassortment, a differentiation of the control can be developed. Purpose: The purpose of this study is to find a way to improve Alutrade's operationalinventory control and theoretically contribute with an analysis of which classification basescompanies in a similar situation should analyse when a model for differentiated control isdeveloped. The study aims to differentiate different operational models to adapt to differentitem characteristics to achieve an increased inventory turnover rate. Method: This study is treated with a deductive approach and contains both a qualitative andquantitative research method. The empirical data collected during the study consists ofinterviews, observations, focus groups and excel documents from the company's businesssystem Jeeves for calculations. The data is collected through unstructured and semi-structuredinterviews and observations. Results: By analysing Alutrade's situation, various problems could be identified in theircurrent work regarding operational inventory control. To remedy these problems, differentclassification bases for a differentiated control were analysed. This is to develop a model thatcan provide the opportunity to increase the stock turnover rate based on Alutrade'sconditions. A classification of articles is presented and gives the opportunity to applydifferent operational layer certification methods to the 9 different categories. The differentiated control handles, among other things, methods for service level, crew pointsystem, EOQ and gives recommendations for how they should be applied for each category.Through this, Alutrade can work to increase its inventory turnover rate and prioritize itsefforts where they make the most sense. Through the application of relevant classificationbases, a framework for differentiated control can be developed and different operationalinventory control methods can then be adapted for each category and provide an increase inthe inventory turnover rate. Keyword: Inventory, operational inventory control, differentiated inventory control,inventory turnover rate, classification bases, order time, order quantity, safety stock, servicelevel, ABC-XYZ analysis / Bakgrund och problemdiskussion: Lagerstyrning är en komplex utmaning som berör olikaaktiviteter om hur lager styrs och hanteras. Styrningen av lager har en stor påverkan påföretags lönsamhet och behöver hanteras på olika sätt beroende på i vilken situation företagetbefinner sig i. För att förbättra operativ lagerstyrning för företag som har kundunika artiklar,hög lagertillgänglighet och en önskan om ökad lageromsättningshastighet behöver olikaaspekter beröras. Olika artiklar i företags sortiment har olika egenskaper och för att styraartiklar på ett framgångsrikt sätt kan en differentiering av styrningen utvecklas. Syfte: Syftet med denna studie är hitta ett sätt att förbättra Alutrades operativa lagerstyrningoch teoretiskt bidra med en analys om vilka klassificeringsgrunder, företag i liknandesituation bör analysera när en modell för differentierad styrning tas fram. Studien syftar tillatt differentiera olika operativa modeller för att anpassa till olika artikelegenskaper för attuppnå en ökad lageromsättningshastighet. Metod: Denna studie behandlas med ett deduktivt angreppssätt och innehåller både enkvalitativ och kvantitativ forskningsmetod. Den empiriska datan som inhämtats under studienutgörs av intervjuer, observationer, fokusgrupper och excelunderlag från företagetsaffärssystem Jeeves för beräkningar. Datan är inhämtad genom ostrukturerade ochsemistrukturerade intervjuer och observationer. Resultat: Genom att analysera Alutrades situation kunde olika problem identifieras i derasnuvarande arbete gällande operativ lagerstyrning. För att åtgärda dessa problem analyseradesolika klassificeringsgrunder för en differentierad styrning. Detta för att ta fram en modell somkan ge möjlighet att öka lageromsättningshastigheten utifrån Alutrades förutsättningar. Enklassificering av artiklar presenteras och ger möjlighet att tillämpa olika operativalagerstyrningsmetoder till de nio olika kategorierna. Den differentierade styrningen hanterarbland annat metoder för servicenivå, besättningspunksystem, EOQ och gerrekommendationer för hur de bör tillämpas för respektive kategori. Genom detta kan4Alutrade arbeta för att öka sin lageromsättningshastighet och prioritera sina insatser dit de görmest nytta. Genom en tillämpning av relevanta klassificeringsgrunder kan ett ramverk fördifferentierad styrning utvecklas och olika operativa lagerstyrningsmetoder kan därefteranpassas för respektive kategori och ge en ökning av lageromsättningshastigheten. Nyckelord: Lager, operativ lagerstyrning, differentierad lagerstyrning,lageromsättningshastighet, klassificeringsgrunder, ordertidpunkt, orderkvantitet,säkerhetslager, servicenivå, ABC-XYZ analys

M. Tech. (Department of Process Control and Computer Systems, Faculty of Engineering and Technology), Vaal University of Technology. / Radio Frequency Identification Technology (RFID) technology is increasingly being used in multiple applications due to its low cost and ability to provide a high quality of identification. The cost benefit of RFID system is seen in the reduction in labor required to perform routine tasks such as inventory. With RFID, inventory-related tasks can be done in substantially less time compared to other commonly used auto-identification systems. Recent research has illustrated the application of RFID in multiple application scenarios. RFID can be used for real-time patient identification and monitoring in hospitals, but also for product expiration-date management in retail industries. Some enterprises in South Africa uses a combination of RFID technology and Internet of Things (IoT) to detect misplaced products and to detect low stock levels. Furthermore, RFID is also used for inventory management in libraries as discussed in this dissertation. In this dissertation, a combination of RFID and ZigBee technologies was used to reduce the time spent to perform inventory in libraries. An inventory management system was designed, simulated and built in order to count and locate books inside a library hence improving inventory process time in libraries. The overall results were satisfactory which lead to the achieving of the objectives set in this study.

This study identifies the concepts of reliability, cost of downtime, cost of spare parts, and procurement lead time as the four key moderators of spare parts availability. These concepts are used to establish a model to manage spare parts inventories. Reliability was assessed in terms of developing failure predictions for major component categories. Cost of downtime was evaluated by identifying various methods for determining costs associated with downtime. Cost of spare parts was examined to find correlations with economic indicators. These correlations were used to predict future price movements. Yearly changes in lead time were identified and correlated with economic indexes to develop movement predictability.

M. Tech. (Industrial Engineering, Faculty of Engineering and Technology) Vaal University of Technology| / Implementing either periodic or continuous inventory review model within most manufacturing-companies-supply chains, as a management tool, incurs higher costs. These high costs affect the system flexibility which in turn affects the level of service required to satisfy customers. However, these effects are not clearly understood. This may be due to the fact that lead time and demand which are important input parameters of the manufacturing supply chain are not designed to be fully utilized under different and uncertain conditions such as seasonality, poor manufacturing, poor supplies and delivery performance, etc. Coming up with a hybrid inventory model which may combine, in some sense a continuous (r, Q) and a periodic (R, S) inventory review models can be useful in dealing with such problem. Therefore, more attention should be first devoted to formulating accurate models for lead time and demand that incorporate uncertainty. This study presents a simulation based approach that assesses the effect of uncertainty on the cost of implementing a continuous (r, Q), periodic (R, S) and hybrid inventory review models while considering appropriate constraint such as customer service and system flexibility. The stochastic representations of demand and lead time are proposed and used in the simulation models. Results reveal that under a unique situation, implementing a continuous (r, Q) inventory review model may cause manager to under-budget while the use of a periodic (R, S) inventory review models may lead to over budget and vice versa. Further investigation shows that the cost of implementing the hybrid inventory model, although higher at the beginning of operation, seems to be the most cost effective one over time. The result also reveal optimal re-order point path and optimal review interval path which when followed, should lead to optimal inventory cost path as demand and lead time fluctuate. Thus, a management guide is proposed that can be used by managers in making inventory decision.

Purpose – To analyze the impact on total cost by inventory control methods under the influence of seasonal demand. The purpose will be answered with following research questions: What inventory control methods can be used when there is seasonal demand? What is the impact of inventory control methods on total cost under the influence of seasonal demand? Method – The study was conducted as a case study and the empirical data was collected through interviews and document study. Both of these contributed to the basis for the analysis and for the calculations in the test of the study. Literature study was conducted and included theories for inventory control methods to answer the first research question, as well as formulas for the methods used to answer the second research question. Findings – It appears from the study, the inventory control methods that can be used when there is seasonal demand and during current planning environment is periodic ordering system and cycle service method. These have been tested further in the study. Seasonal index was considered an important method since it dimensions demand which to a high degree regulate the inventory levels and thereby the result of the inventory control methods. Further the study compares none theoretical inventory control methods and theoretical inventory control methods impact on total cost. It is shown that carrying costs, as a part of total cost, can be reduced by 25% during the peak season and 62% during off-season. This without changing the deliverability. Alternatively, the deliverability can be increased by 10% by using inventory control methods without increasing the total cost of the inventory. Implications – The theoretical contribution of the study is that it has increased the knowledge concerning inventory control methods when there is seasonal demand, and the possible results they might bring. The empirical contribution of the study is that companies can use the study as an indication of the economic benefits and motivation for implementing theoretical inventory control methods. Limitations – The tested inventory control methods did not alter the ordering cost, which to a high degree can have an impact on the total cost. The study also shows a possible impact on the inventory control during the current planning environment. If the planning environment changes, the result of the study can be different.

O problema de controle de estoques com demanda não estacionária e lead-time positivo tem se tornado cada vez mais relevante em virtude da crescente tendência de redução do ciclo de vida dos produtos e internacionalização das cadeias de suprimentos. Embora haja uma solução exata para a minimização do custo esperado da política de estoques para este cenário, baseado no método de programação dinâmica, o custo computacional deste método ainda é considerado elevado. Este trabalho detalha e avalia através de simulação o método exato e duas aproximações para a minimização do custo esperado da política de estoques, em termos do desempenho em custo e eficiência computacional. Os resultados experimentais permitem a análise dos métodos disponíveis. Enquanto a abordagem heurística de Bollapragada e Morton, que utiliza o nivelamento da demanda não estacionária, perde desempenho de custo com o aumento do lead-time, a nova heurística proposta, que aproxima os parâmetros da política ótima por valores limitantes, produz resultados sucessivamente melhores com o aumento do lead-time. / The inventory control problem with nonstationary demand and positive lead-time has become increasingly important due to the growing trend of reduction in product life cycle and internationalization of the supply chain. Although there is an exact solution to the minimization of the expected cost of inventory policy on this environment, through the method of dynamic programming, the computational cost of this method is still considered high. This work details and evaluates through simulation the exact method and two heuristic solutions for the minimization of expected cost of inventory policy, in terms of cost performance and computational efficiency. The experimental results allow the analysis of the available methods. While the Bollapragada and Morton heuristic approach, which levels the non-stationary demand, decreases the cost performance when lead-time is increased, the new heuristic proposed, that approximates the optimal policy parameters by limiting values, successively produces better results with increasing lead-times.

Application of multisource feedback (MSF) increased dramatically and became widespread globally in the past two decades, but there was little conceptual work regarding self-other agreement and few empirical studies investigated self-other agreement in other cultural settings. This study developed a new conceptual framework of self-other agreement and used three samples to illustrate how national culture affected self-other agreement. These three samples included 428 participants from China, 818 participants from the US, and 871 participants from globally dispersed teams (GDTs). An EQS procedure and a polynomial regression procedure were used to examine whether the covariance matrices were equal across samples and whether the relationships between self-other agreement and performance would be different across cultures, respectively. The results indicated MSF could be applied to China and GDTs, but the pattern of relationships between self-other agreement and performance was different across samples, suggesting that the results found in the U.S. sample were the exception rather than rule. Demographics also affected self-other agreement disparately across perspectives and cultures, indicating self-concept was susceptible to cultural influences. The proposed framework only received partial support but showed great promise to guide future studies. This study contributed to the literature by: (a) developing a new framework of self-other agreement that could be used to study various contextual factors; (b) examining the relationship between self-other agreement and performance in three vastly different samples; (c) providing some important insights about consensus between raters and self-other agreement; (d) offering some practical guidelines regarding how to apply MSF to other cultures more effectively.

Thesis. 1979. Ph.D.--Massachusetts Institute of Technology. Alfred P. Sloan School of Management. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY / Bibliography: p. 336-338. / Ph.D.

O problema de controle de estoques com demanda não estacionária e lead-time positivo tem se tornado cada vez mais relevante em virtude da crescente tendência de redução do ciclo de vida dos produtos e internacionalização das cadeias de suprimentos. Embora haja uma solução exata para a minimização do custo esperado da política de estoques para este cenário, baseado no método de programação dinâmica, o custo computacional deste método ainda é considerado elevado. Este trabalho detalha e avalia através de simulação o método exato e duas aproximações para a minimização do custo esperado da política de estoques, em termos do desempenho em custo e eficiência computacional. Os resultados experimentais permitem a análise dos métodos disponíveis. Enquanto a abordagem heurística de Bollapragada e Morton, que utiliza o nivelamento da demanda não estacionária, perde desempenho de custo com o aumento do lead-time, a nova heurística proposta, que aproxima os parâmetros da política ótima por valores limitantes, produz resultados sucessivamente melhores com o aumento do lead-time. / The inventory control problem with nonstationary demand and positive lead-time has become increasingly important due to the growing trend of reduction in product life cycle and internationalization of the supply chain. Although there is an exact solution to the minimization of the expected cost of inventory policy on this environment, through the method of dynamic programming, the computational cost of this method is still considered high. This work details and evaluates through simulation the exact method and two heuristic solutions for the minimization of expected cost of inventory policy, in terms of cost performance and computational efficiency. The experimental results allow the analysis of the available methods. While the Bollapragada and Morton heuristic approach, which levels the non-stationary demand, decreases the cost performance when lead-time is increased, the new heuristic proposed, that approximates the optimal policy parameters by limiting values, successively produces better results with increasing lead-times.

The thesis focuses on the analysis of various extensions of the classical multi-period single-item stochastic inventory problem. Specifically, we investigate two particular approaches of modeling risk in the context of inventory management: risk-averse models and robust formulations. We analyze the classical newsvendor problem utilizing a coherent risk measure as the objective function. Properties of coherent risk measures allow us to offer a unifying treatment of risk averse and min-max type formulations. We show that the structure of the optimal policy of the risk-averse model is similar to that of the classical expected value problem for both single and multi-period cases. The result carries over even when there is a fixed ordering cost. We expand our analysis to robust formulations of multi-period inventory problems. We consider both independent and dependent uncertainty sets and prove the optimality of base-stock policies for the general problem formulation. We focus on budget of uncertainty approach and develop a heuristic that can also be employed for a class of parametric dependency structures. We compare our proposed heuristic against alternative solution techniques.