This dissertation consists of three independent sections: In the first part, focusing on the auto industry we look at the challenges and solution strategies of employing build-to-order (BTO) with global supply. We consider some familiar tools for managing domestic supply and exploit them for managing international supply, and propose new methods. We study frequency of supply as a way to improve performance. We study the impact of forecast accuracy, and conclude that improvements there alone may not be sufficient to obtain desired savings. Within this perspective we look at a new shipping policy, 'Ship-to-Average", which prescribes sending a fixed quantity, based on the long term average forecast, with each shipment and making adjustments only if the inventory strays outside a prescribed range. In the second part we look at a Brownian control problem. When a manufacturer places repeated orders with a supplier to meet changing production requirements, he faces the challenge of finding the right balance between holding costs and the operational costs involved in adjusting the shipment sizes. Consider a storage system whose content fluctuates as a Brownian motion in the absence of control. A linear holding cost is incurred continuously. Inventory level can be adjusted by any quantity at a fixed plus proportional cost. We show control band policies are optimal for the average cost problem and calculate the optimal policy parameters. This form of policy is described by three parameters q, Q, S. When the inventory falls to 0 (rises to S), the controller expedites (curtails) shipments to return it to q (Q). Developing techniques based on Lagrangian relaxation we show that this type of policy is optimal even with constraints on the size of adjustments and on the maximum inventory level. The Brownian Control problem can be viewed as an idealization --without delivery delays, of the problem of supplying BTO operations, and provides some theoretical explanation for the Ship-to-Average policies. In fact, Ship-to-Average policies are a practical implementation of Control Band policies in the setting with delivery delays. Finally, we explore the power and applicability of the Lagrangian approach developed in the second part.

This dissertation focuses on issues associated with the value of information in models of sequential decision making under uncertainty. All of these issues are motivated by inventory management problems. First, we study the effect of the accuracy of inventory counts on system performance when using a zero-memory controller in an inventory system that is modeled as a partially observed Markov decision process (POMDP). We derive conditions for which improving the accuracy of inventory counts will either (i) improve system performance, (ii) degrade system performance or (iii) will not affect system performance. With a computational study, we determine the range of profitability impacts that result from inaccurate inventory counts when using reasonable zero-memory control policies. Second, we assess the value of demand observation quality in an inventory system with Markovian demand and lost sales. Again, the POMDP serves as a problem model, and we develop computationally tractable suboptimal algorithms to enable the computation of effective lower bounds on system profitability when demand observations are noise-corrupted. We then extend our results toconsider the effects that product substitution has on system performance. We show that systems with low demand variability, high holding cost levels, and high levels of substitution benefit more from demand bservability than systems with high demand variability, low holding cost levels, and low levels of substitution. Third, to enhance our understanding of sequential inventory control with substitutable products, we analyze a two-item inventory problem with known deterministic primary demand, but stochastic one-way substitution. We model this problem as a MDP and show that a decision rule that minimizes the single period cost function, when applied at every decision epoch over the infinite horizon, is an optimal policy for the infinite horizon problem. A definition of increased substitutability is presented, and it is shown that increased substitutability never increases optimal expected total discounted cost.

Sedan den 1 januari 2011 är det obligatoriskt för revisorer i Sverige att tillämpa de internationella redovisningsstandarderna som återfinns i ISA. Standarderna syftar till att upprätthålla revisionskvalitet, stabilitet och transparens i finansiella rapporter. De företag som omfattas av revisorskravet och har ett varulager som anses vara av väsentlighet för de finansiella rapporterna ska årligen kontrollinventeras av revisorn. Till följd av covid-19-pandemin infördes smittförebyggande restriktioner som begränsade fysiska möten, såväl arbetsrelaterade som privata. Det kunde tänkas att revisorernas utförande av kontrollinventeringar av varulager påverkades av de avvikande omständigheterna. Forskning gällande revisorers utförande av kontrollinventeringar av varulager under avvikande omständigheter fanns inte i stor utsträckning vid tidpunkten för denna studie.  Syftet med studien är att öka förståelsen för hur revisorer genomför kontrollinventeringar av varulager under avvikande omständigheter för att upprätthålla tillförlitlighet i de finansiella rapporterna. För att uppnå syftet har den empiriska insamlingen i studien främst utgått från ISA 501. Standarden redogör för granskningsåtgärder vid utförandet av kontrollinventeringar av varulager och kräver revisorns fysiska närvaro för att säkerställa tillräcklighet och ändamålsenlighet i bevisinsamlingen. En kvalitativ forskningsstrategi tillämpades i genomförandet av studien och empiriska data har insamlats genom intervjuer. Respondenterna som deltog i studien är 13 yrkesverksamma revisorer från sex olika orter i Sverige.  Studien visar att revisorernas möjlighet att genomföra kontrollinventeringar vid rätt tidpunkt inte påverkats till följd av de avvikande omständigheter som uppstått på grund av covid-19-pandemin. Däremot har tillvägagångssättet anpassats med hänsyn till de smittförebyggande restriktioner som varit gällande vid perioden för kontrollinventeringarna. Flera av kontrollinventeringarna har genomförts digitalt via videosamtal. Samtliga granskningsåtgärder som framgår av ISA 501 har vidtagits oavsett om revisorn varit fysiskt närvarande vid kontrollinventeringar eller utfört dem på distans. Även om revisorn har kunnat genomföra alla granskningsåtgärderna har möjligheten att använda de mänskliga sinnena begränsats i och med att kontrollinventeringarna skett genom en mobil- eller datorskärm. En orsak till svårigheter som uppkommit vid digitala kontrollinventeringar är tekniska problem i form av bland annat bristfällig internetuppkoppling. Faktorer som är avgörande för om revisorns fysiska närvaro ses som nödvändig vid kontrollinventering av varulager är kundkännedom, varulagrets storlek och typ av lagerartiklar. Dessa faktorer kan påverka om revisonsbevisen som insamlas vid digitala kontrollinventeringar anses vara tillförlitliga. / Since January 1st, 2011, it is mandatory for auditors in Sweden to comply with the international auditing standards ISA. The standards aim to maintain audit quality, stability and transparency in financial reports. Companies that are covered by the auditor requirement and have inventories that are of materiality to the financial statements must annually be inventoried by the auditor. As a result of the covid-19 pandemic, restrictions were introduced and limited the possibilities to arrange private and work-related in-person meetings. It's conceivable that the auditors' accomplishment of inventory controls was affected by the deviating circumstances. Research regarding auditors’ performances of inventory controls during deviating circumstances did not exist to a wide extent at the time this study was conducted.  The purpose of the study is to increase the understanding of how auditors accomplish inventory controls during deviating circumstances to maintain reliability in the financial statements. To fulfill the purpose, the empirical collection in the study has primarily been based on ISA 501. The standard accounts for audit measures for the accomplishment of inventory controls and requires the auditor’s physical presence to ensure adequacy and appropriateness. A qualitative research strategy was adopted in the course of the study and the empirical data was collected through interviews. The respondents who participated in the study were 13 professional auditors from six different locations in Sweden.  The study shows that the auditors' possibilities to perform inventory controls at the right time were not affected by the covid-19 pandemic. However, the approach has been adapted to the restrictions that were in force during the period of the inventory controls. Several of the inventory controls have been performed digitally through video calls. All audit measures set out in ISA 501 have been performed regardless of whether the auditor has been physically present during the inventory controls or performed them remotely. Although the auditors have been able to perform all the audit measures, their possibilities have been limited, as the human senses could not be used to the same extent through a mobile or computer screen. One of the arisen difficulties with digital inventory controls is technical issues in the form of, among other things, insufficient internet connection. Factors that are crucial for whether the auditor's physical presence is considered necessary in inventory controls are customer knowledge, the size of the inventory and the type of inventory items. These factors can decide if the audit evidence collected during digital inventory controls can be considered reliable.

Submitted in fulfilment of the requirements of the degree of Masters of Technology in Cost and Management Accounting, Durban University of Technology, Durban, 2015. / The Stores Division reportedly found it very difficult to control inventories as well as executing roles and responsibilities allocated in the section. The aims of this study were to identify factors affecting the success of inventory control and to assess strategies used by the Stores Division of the eThekwini Municipality in Durban to control inventory stocks. In order to arrive at the deep structure underpinning inventory control, three theoretical frameworks were used, i.e., stock diffusion theory, application control theory and inventory control in theory and practice. This case study was census, descriptive, cross-sectional and predominantly quantitative in nature with only two open-ended questions. The 57 questionnaires were administered by members of staff at the Stores and Procurement Divisions of the eThekwini Municipality in Durban. Data were analysed using descriptive and inferential statistics and categorised according to themes. The IBM Statistical Package for Social Sciences (SPSS) version 21.0 was used to determine statistical results. The findings of the study revealed that employees lack proper training and education and that there is poor inventory control planning, lack of staff communication and lack of procurement time management when processing inventory orders. Respondents also indicated that there are no common strategies in place to control inventories. The study recommends that the Stores Division should consider the levels of staff qualifications, provide more staff training, and improve inventory control planning; communication; time management, and instigate innovative strategies in order to eradicate growing costs of inventory stocks. Moreover, the internal control processes need to be mapped according to the various roles identified.

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

Submitted by Elba Lopes (elba.lopes@fecap.br) on 2016-06-24T17:13:11Z No. of bitstreams: 1 Antonio_Carlos_Fiore.pdf: 718863 bytes, checksum: 7dc6833a7e9aa377933d5c6f99f6bd59 (MD5) / Made available in DSpace on 2016-06-24T17:13:11Z (GMT). No. of bitstreams: 1 Antonio_Carlos_Fiore.pdf: 718863 bytes, checksum: 7dc6833a7e9aa377933d5c6f99f6bd59 (MD5) Previous issue date: 2016-03-22 / The aim of this study was to observe how companies acting in fashion market measure, evaluate and emphasize their inventory in financial statements. Moreover, how they deal with the risks of its fast obsolescence. The fastest alterations in fashion tendencies; the capacity or not to anticipate, identify and answer to changes in consumers?? tastes; the interruptions in the flow of goods, that could cause breaks in the supply chain; the growing competition; the unpredictability in consume, and planning errors upon the development of new collections could be harmful for stored products waiting for its customers ??? all of them force companies to charge prices lower than their costs. The user of financial statements needs to be warned of such risks, because they could affect the existing inventory. To reach the proposed aims, the practices adopted in the main international companies of this sector were analyzed, by means of published financial statements, and compared with those adopted by Brazilian companies listed in Bovespa Stock Exchange. In addition, through interviews, it was possible to identify the treatment given to the same theme by Brazilian companies unlisted in Bovespa Stock Exchange. It was clear that international and national listed companies correctly attend to what is established in accounting standards. On the other hand, in national unlisted companies, the adoption of these practices needs development. It was also possible to verify that financial statements of American companies provide their users with more details concerning risks involving operations with goods, when compared to information provided by European and Brazilian companies. / O objetivo deste estudo foi observar a forma pela qual as empresas atuantes no mercado da moda mensuram, avaliam e evidenciam seus estoques nas demonstra????es financeiras e de que maneira tratam os riscos de sua r??pida obsolesc??ncia. As mudan??as cada vez mais r??pidas nas tend??ncias de moda; a capacidade ou n??o de se antecipar, identificar e responder ??s altera????es nos gostos dos consumidores; as interrup????es no fluxo de mercadorias que podem causar rupturas no supply chain; o acirramento da concorr??ncia; a imprevisibilidade do consumo e, os erros de planejamento na elabora????o de novas cole????es podem ser danosos para os produtos estocados ?? espera de seus consumidores, obrigando as empresas a praticar pre??os muitas vezes inferiores ao seu pr??prio custo. O usu??rio das demonstra????es financeiras precisa ser informado a respeito desses riscos, pois estes podem impactar os estoques existentes. Para alcan??ar os objetivos propostos, foram analisadas, por meio das demonstra????es financeiras publicadas, as pr??ticas cont??beis adotadas nas principais empresas internacionais desse segmento, comparando-as ??quelas adotadas pelas empresas brasileiras, listadas na Bovespa. Complementarmente, atrav??s de entrevistas, buscou-se identificar o tratamento dado a esse mesmo tema pelas empresas brasileiras n??o listadas na Bovespa. Ficou claro que tanto as empresas internacionais, quanto as nacionais listadas, atendem corretamente ao que est?? estabelecido nas normas cont??beis, enquanto que nas empresas nacionais, de capital fechado, a ado????o dessas pr??ticas cont??beis, ainda carece de evolu????o. Pode ser observado, ainda, que as demonstra????es financeiras das empresas norte-americanas fornecem, aos seus usu??rios, mais detalhes a respeito dos riscos inerentes ??s opera????es com mercadorias, quando comparadas ??s informa????es fornecidas pelas empresas europeias e brasileiras.

Shrinking profit margins in the high technology industry has led companies to attempt to increase profits through an increased focus on after-market services. As part of that effort, service parts logistics, which manages the post-sales distribution of spare parts needed to maintain and repair products in use, has gained importance. In an effort to improve Service Parts Logistics (SPL) operations, we integrate facility location and inventory stocking decisions while classifying facilities based on their assignment; dedicated facilities that are assigned solely to individual customers (located on-site of the customer, serving only that customer), and shared facilities that are assigned to a subset of customers. The introduction of dedicated facilities simplifies the overall problem formulation in certain special cases. In one such special case where there is only one facility and none of the customers are within its service time window, the overall problem reduces to a binary knapsack formulation. This can be solved in pseudo-polynomial time through the dynamic programming algorithm for such problems. Nonetheless, even in the general case, we identify conditions under which a dedicated facility will always be opened. Computational results show that this observation is used by solvers as a preprocessing step, thus loosening some hard constraints. As a result, some of these problems are solved in less time than the corresponding problems without the dedicated facilities. However, dedicated facilities become advantageous mainly in sparse networks as opposed to dense networks. Apart from low network density, low holding cost and relatively high demand are two other system parameters that encourage the opening of dedicated facilities. SPL can be further improved by sharing inventory across shared facilities, which is already a common practice in real SPL systems. In this case, Markov chains can be used to estimate fill rates, but the process is iterative. However, under the low demand assumption of parts in SPL, we derive analytical formulae of estimating fill rates and thus incorporate inventory sharing within the network design and inventory optimization model. Special cases of this problem can be solved by an alternative binary knapsack formulation. Computational results show that large instances can be solved instantaneously, and we also identify a greedy heuristic that provides bounds on average within 0.12% of the optimal solution. We observe maximum benefit from inventory sharing when there exists large demand in the area overlapping the time window of both shared facilities and when inventory replenishment rates are high. However, we also identify conditions on the system parameters where inventory sharing could increase cost and/or decrease service in comparison with not-sharing. The combined problem of inventory sharing with customer dedicated facilities is formulated based on a binary knapsack structure. However, the problem size increases exponentially with solution time. Therefore, we construct another greedy heuristic by combining the inventory sharing heuristic and a special case algorithm for a single dedicated facility. A large size problem that takes almost a minute to be solved by conventional branch and bound is solved in less than a second using the greedy heuristic. We also show that for a given demand network, the combined problem achieves 40-60% reduction in total cost within 1% of the time taken by the problem without inventory sharing and without dedicated facilities. Another interesting result is that in some cases, adding new customers to a given inventory sharing system helps to reduce the cost and/or increase service. / text

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Effective management of spare parts inventory is essential to companies because it influences inventory costs and asset utilization. The vast and diverse portfolio of spare parts, intermittent demand patterns and contradicting objectives between departments are examples of some of the factors that complicate Spare Parts Management (SPM). Managers of spare parts are faced with trade-off decisions between risk and cost on a daily basis. These decisions include, amongst many, determining appropriate stock levels and order frequencies. Despite the importance of SPM, decisions are however often made intuitively in practice with little factual support, and the decision-making process is commonly constrained within departmental silos. Even though there is a large body of academic knowledge on this topic, practical applications of spare parts inventory solutions lag behind theoretical studies. The majority of studies in literature focus on single components of SPM, such as demand forecasting and parts classification, whereas fewer studies consider the decision-making process itself. This study proposes a decision-making framework for spare parts inventory management. The framework is based on a wide-ranging literature review that focuses on capturing the essence of Spare Parts Management (SPM), but also acknowledges the interconnectedness of the problem. Therefore, core inventory management principles, as well as closely related topics such as Supply Chain Management (SCM) and Physical Asset Management (PAM), are studied in the context of spare parts. The broad scope of the literature study leads to a holistic approach to the problem and prevents sub-optimization. The proposed framework condenses principles from various fields of study (SCM, PAM, Classification and Inventory Management) into a stepwise methodology presented as a decision-making framework. The objective of the framework is to provide managers with a structured process, based on factual information, to enable better decision-making in the field. Furthermore, the framework aims to capture the fundamentals of SPM in a simplistic manner to ease the adoption of the framework in practice. A case study is conducted in the South African mining industry to validate the framework. The case study demonstrates that the framework is practical, provides structured guidance, and assists managers to make trade-off decisions in managing spare parts inventory. / AFRIKAANSE OPSOMMING: Effektiewe voorraadbestuur van onderdele is belangrik vir maatskappye omdat dit voorraadkoste en die benutting van bates beïnvloed. Die bestuur van onderdele is ’n komplekse probleem. Ondermeer is die portefeulje van onderdele items breed en divers, die vraagpatrone sporadies en word die voorraadvlakke geaffekteer deur kontrasterende doelwitte tussen verskillende departemente. Bestuurders van onderdele word daagliks gekonfronteer met besluite rakende risiko’s en kostes, soos om toepaslike voorraadvlakke te bepaal en om te besluit wanneer om bestellings te plaas. Hierdie besluite word dikwels intuïtief geneem met min feitelike ondersteuning en insette in die besluitnemingsproses word gereeld beperk tot sekere departemente. Ten spyte van die geweldige akademiese belang in die onderwerp, is daar min suksesvolle praktiese toepassings. Die meerderheid van studies in die literatuur fokus op spesifieke elemente van onderdele bestuur, soos vooruitskatting en klassifisering van parte, terwyl minder op die besluitnemingsproses konsentreer. Hierdie studie stel ’n besluitnemingsraamwerk vir die bestuur van onderdele voorraad voor. Die raamwerk is gegrond op ’n deeglike literatuurstudie wat die essensie van onderdele bestuur ondersoek, maar ook die interverbondenheid van die probleem in ag neem. Voorraadbestuurbeginsels en verwante onderwerpe soos Voorsieningskettingbestuur en Fisiese Batebestuur word dus bespreek. Die breë omvang van die literatuurstudie lei tot ’n holistiese benadering wat sub-optimering van die probleem voorkom. Die voorgestelde raamwerk som beginsels uit verskillende relevante studievelde op in ’n stapsgewyse metode wat voorgestel word as ’n besluitnemingsraamwerk. Die doel van die raamwerk is om bestuurders te voorsien met ’n gestruktureerde proses, gebaseer op feitelike inligting, om besluitneming in die veld te verbeter. Verder poog die raamwerk om die fundamentele konsepte in voorraadbestuur vas te vang in ’n eenvoudige manier sodat die raamwerk maklik geïmplementeer kan word in die praktyk. Die voorgestelde raamwerk is gevalideer deur middel van ’n gevallestudie in die Suid-Afrikaanse mynbedryf. Die gevallestudie toon dat die voorgestelde raamwerk prakties is, die besluitnemingsproses op ’n gestruktureerde wyse lei, en bestuurders help om beter, ingeligte besluite te neem.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries