No description available.

The Global Supply Chain Forum (Stanford Global Supply Chain Forum Web Resource, http://www.stanford.edu/groups/scforum) defines supply chain management (SCM) as “Supply chain management is the integration of key business processes from end user through original suppliers that provides products, services and information that add value for customer and other stakeholders.” The rapid development of the Internet has dramatically changed the traditional definitions of manufacturer, suppliers and customers. Newer approaches to supply chain management attempt to organize the supply chain as a network of cooperating intelligent agents, each performing one or more supply chain functions and each coordinating actions with one another. This research is aimed at creating a viable model of a single manufacturer single supplier collaborative supply chain system using a Vendor Managed Inventory (VMI) system. The research further uses known inventory performance parameters to performance benchmark the VMI system with traditional push-pull systems, develop a collaborative forecasting spreadsheet solution and a best alternative ordering policy amongst EOQ, Monthly, JIT and VMI policies under known lead time and a variety of demand distribution functions. / Master of Science

No description available.

No presente trabalho é proposto um modelo de simulação de uma cadeia de suprimentos integrada com adoção da estratégia de VMI (Vendor Managed Inventory) entre uma empresa do setor de minério de ferro e alguns de seus fornecedores estratégicos. O modelo baseia-se em uma estrutura de avaliação de sistemas VMI adaptada de Sarpola et al. (2007) em conjunto com as configurações de cadeias de suprimentos propostas por Holmström et al (2003), o que permite medir o desempenho da cadeia de suprimentos segundo 3 níveis de integração. É feita uma revisão bibliográfica dos conceitos da estratégia de VMI, políticas de estoque em sistemas integrados, compartilhamento e grau de visibilidade de informações ao longo da cadeia de suprimentos. Os resultados obtidos possibilitam realizar uma análise quantitativa dos benefícios do VMI, onde são considerados demanda estocástica, lead time aleatório, produtos com características diferentes, compartilhamento de informações, visibilidade parcial da cadeia de suprimentos, lotes variáveis, cálculo dos estoques de segurança considerando informações dos pedidos, demanda real do cliente e erros de previsão. / In this paper we proposed a simulation model of an integrated supply chain with the adoption of VMI (Vendor Managed Inventory) strategy between a company of the iron ore and some of its strategic suppliers. The model is based on a framework for evaluating VMI systems adapted from Sarpola et al. (2007) together with the configurations of supply chains proposed by Holmström et al (2003), which measures the performance of the supply chain using 3 levels of integration. It is a literature review of the concepts of the strategy of VMI, inventory policies in integrated systems, sharing and degree of visibility of information throughout the supply chain. The results allowed to perform a quantitative analysis of the benefits of VMI, which are considered as stochastic demand, random lead time, products with different characteristics, information sharing, partial visibility of the supply chain, lots of variables, calculation of safety stocks based on information from client orders, actual customer demand and forecasting errors.

O processo de automatização de teste de software possui alto custo envolvido em sistemas de larga escala, pois exigem cenários de teste complexos e tempos de execução extremamente longos. Além disso, cada etapa do processo de teste requer recursos computacionais e um tempo considerável para a execução de muitos casos de teste, tornando-se um gargalo para as empresas de Tecnologia da Informação (TI). Neste contexto, os benefícios e oportunidades oferecidos pela combinação da computação em nuvem com o Teste como Serviço (Testing as a Service, TaaS), que é considerado um novo modelo de negócio e de serviço atraente e promissor, podem proporcionar um impacto positivo na redução do tempo de execução dos testes de maneira custo-efetiva e aumentar o retorno sobre o investimento ou Return on investment (ROI). Todavia, existe o problema de vendor lock-in, que é o aprisionamento do usuário à plataforma de um fornecedor específico ou serviço de teste, ocasionado pela dificuldade de migrar de um fornecedor TaaS para outro, limitando a utilização dessas novas tecnologias de maneira efetiva e eficiente, impedindo assim, a ampla adoção do TaaS. Como os estudos existentes não são rigorosos ou conclusivos e, principalmente, devido à falta de evidência empírica na área de serviço de teste, muitas questões devem ser investigadas na perspectiva da migração entre os provedores de TaaS. O objetivo deste trabalho é reduzir o impacto ocasionado pelo problema de vendor lock-in no processo de automatização de testes na computação em nuvem, na escrita, configuração, execução e gerenciamento dos resultados de testes automatizados. Neste contexto, foi desenvolvido o protótipo da abordagem intitulada Multi-TaaS por meio de uma biblioteca Java como prova de conceito. A abordagem Multi-TaaS é uma camada de abstração e a sua arquitetura permite abstrair e flexibilizar a troca de fornecedores de TaaS de forma portável, pois permite encapsular toda a complexidade da implementação do engenheiro de software ao desacoplar o teste automatizado de qual plataforma TaaS ele será executado, bem como abstrair os aspectos da comunicação e integração entre as APIs REST proprietárias dos diferentes fornecedores de TaaS. Além disso, a abordagem Multi-TaaS possibilita também sumarizar os resultados dos testes automatizados de forma independente das tecnologias da plataforma TaaS subjacente. Foram realizadas avaliações comparativas da eficiência, efetividade, dificuldade e do esforço de migração entre as abordagens Multi-TaaS e abordagem convencional, por meio de experimentos controlados. Os resultados deste trabalho indicam que a nova abordagem permite facilitar a troca do serviço de teste, melhorar a eficiência e, principalmente, reduzir o esforço e os custos de manutenção na migração entre fornecedores de TaaS. Os estudos realizados no experimento controlado são promissores e podem auxiliar os engenheiros de software na tomada de decisão quanto aos riscos associados ao vendor lock-in no TaaS. Por fim, a abordagem Multi-TaaS contribui, principalmente, para a portabilidade dos testes automatizados na nuvem e da sumarização dos resultados dos testes e, consequentemente, possibilita que o modelo de serviço TaaS na computação em nuvem seja amplamente adotado, de forma consciente, no futuro. / The automation of software testing involves high costs in large-scale systems, since it requires complex test scenarios and extremely long execution times. Moreover, each of its steps demands computational resources and considerable time for running many test cases, which makes it a bottleneck for Information Technology (IT) companies. The benefits and opportunities offered by the combination of cloud computing and Testing as a Service (TaaS), considered a new business and service model, can reduce the execution time of tests in a cost-effective way and improve Return on Investment (ROI). However, the lock-in problem, i.e., the imprisonment of the user in the platform of a specific vendor or test service caused by the difficult migration from one TaaS provider to another limits the effective use of such new technologies and prevents the widespread adoption of TaaS. As studies conducted are neither rigorous, nor conclusive, and mainly due to the lack of empirical evidence, many issues must be investigated from the perspective of migration among TaaS providers. This research aims at reductions in the impact of the vendor lock-in problem on the automation process of testing in cloud computing, writing, configuration, execution and management of automated test results. The prototype of the Multi- TaaS approach was developed through a Java library as a proof of concept. The Multi-TaaS approach is an abstraction layer and its architecture enables the abstraction and flexibilization of the exchange of TaaS providers in a portable way, once the complexity of the software engineers implementation can be encapsulated. The two main advantages of Multi-TaaS are the decoupling of the automated test from the TaaS platform on which it will be executed and the abstraction of the communication and integration aspects among the proprietary REST APIs of the different TaaS providers. The approach also enables the summarization of automated test results independently of the underlying TaaS platform technologies. A comparative evaluation between Multi-TaaS and conventional migration approaches regarding the difficulty, efficiency, effectiveness and effort of migration among TaaS providers was conducted through controlled experiments.The results show the approach facilitates the exchange of test service, improves efficiency and reduces the effort and maintenance costs of migration among TaaS providers. The studies conducted in the controlled experiment are promising and can assist software engineers in decision-making regarding the risks associated with vendor lock-in in TaaS. The Multi-TaaS approach contributes mainly to the portability of automated tests in the cloud and summarization of their results. Finally, this research enables also the widespread adoption of the TaaS service model in cloud computing, consciously, in the future.

Η αξιολόγηση και επιλογή προμηθευτών αποτελεί μια απαραίτητη επιχειρησιακή λειτουργία για την επίτευξη βέλτιστων δυνατών προμηθειών. Λόγω της φύσης του προβλήματος αυτού, οι μέθοδοι Πολυκριτηριακής Ανάλυσης μπορούν να παίξουν αποφασιστικό ρόλο στην επίλυσή του. Η εργασία αυτή μελετά και παρουσιάζει τα πιο συνηθισμένα κριτήρια καθώς και τις πιο διαδεδομένες μεθόδους της Πολυκριτηριακής Ανάλυσης για την αξιολόγηση και επιλογή προμηθευτών των επιχειρήσεων. Στο πρώτο μέρος της εργασίας αυτής, παρουσιάζεται το θεωρητικό υπόβαθρο, όπου γίνεται αναφορά στις έρευνες προηγούμενων μελετητών του προβλήματος της αξιολόγησης και επιλογής προμηθευτών, ομαδοποιώντας μια σειρά από τους σημαντικότερους παράγοντες για την επιλογή προμηθευτών. Στη συνέχεια παρουσιάζονται οι πλέον χρηστικές μέθοδοι Πολυκριτηριακής Ανάλυσης στην αξιολόγηση προμηθευτών με αντίστοιχα παραδείγματα. Στο δεύτερο μέρος γίνεται εφαρμογή της μεθόδου της Αναλυτικής Διαδικασίας Ιεράρχησης (ΑΗΡ) συνδυάζοντάς την με Γραμμικό Προγραμματισμό, επί των πραγματικών δεδομένων της μικρομεσαίας επιχείρησης επεξεργασίας νερού Health Affair, για αξιολόγηση και επιλογή των προμηθευτών της. / Vendor selection and evaluation is a very important process for all kinds of firms. Due to the nature of the vendor selection problem, Multicriteria methods can play a decisive role to its solution. This work examines and presents the most commonly used criteria and the most widespread Multicriteria methods for vendor selection and evaluation. In the first part of the project, the Theoretical Framework is presented, where the work of previous researchers is mentioned, by grouping some of the most vital criteria in vendor selection process. Moreover, the most useful Multicriteria methods in vendor selection are analyzed into their corresponding examples. In the second part of the project, the method of Analytical Hierarchy Process (AHP) in combination with Linear Programming is implemented on the real data of a Greek water treatment SME.

Le développement des technologies de l’information et de la communication que connait notre siècle a grandement facilité les pratiques d’échanges d’informations au sein des chaînes logistiques. Ces pratiques ont pu ainsi évoluer vers de nouvelles formes de collaborations entre entreprises, telles que le Partage d’Informations (PI) et le Vendor Managed Inventory (VMI). Le VMI est un mécanisme de coordination dans lequel le fournisseur a la responsabilité de la gestion des stocks de son client. Ce mécanisme repose sur plusieurs principes parmi lesquels un partage d’informations très développé entre les parties qui s’y engagent. Le PI et le VMI sont adoptés par les entreprises pour permettre une augmentation des profits et une réduction des coûts. Toutefois, leurs résultats sont mitigés et nécessitent encore un approfondissement de leur compréhension. La contribution de cette thèse se situe dans l’analyse des impacts de ces mécanismes sur des chaînes logistiques où tous les maillons sont des entreprises de production dont les efficacités peuvent être différentes. Pour ce faire, plusieurs scénarios ont été étudiés sur des chaînes logistiques constituées de trois échelons, chaque échelon peut appartenir à quatre classes d’efficacité. Ces chaînes peuvent répondre à deux types de demande du marché final ; une demande stable ou une demande variable. De plus, plusieurs mécanismes de coordination sont étudiés : les mécanismes de gestion standard, de partage d’informations entre deux échelons, de partage d’informations entre trois échelons, de VMI entre deux échelons, puis de VMI étendu aux trois échelons. L’outil utilisé pour mener ces expérimentations est le logiciel de simulation à évènements discrets Arena. L’interprétation des résultats a montré que le mécanisme de coordination avec partage d’informations n’a pas eu d’amélioration très significative sur les résultats. En effet, puisque les entreprises ont des capacités de production finies, la disponibilité de l’information n’a pas permis d’obtenir des résultats différents. Le VMI, de son côté, a pu réaliser des réductions des stocks et des coûts de la chaîne logistique. Ces réductions ont été plus importantes chez les chaînes logistiques dont les maillons sont de faibles efficacités. Chez ces dernières, ce sont les deux parties concernées par le VMI (le fournisseur et le donneur d’ordres) qui ont tiré des avantages du VMI. Chez les chaînes logistiques constituées de maillons de haute efficacité, le VMI a permis une réduction des coûts moins importante, car ces chaînes logistiques sont déjà de performance élevée. Pour celles ci, c’est le client qui a tiré profit du VMI, alors que le fournisseur VMI a subi une augmentation des coûts suite à l’augmentation de la fréquence de transport qu’a impliqué ce mécanisme. / The advent of new information and communication technology has greatly facilitated the information exchange practices within supply chains. These practices recently evolved into new forms of collaborations between companies such as Information Sharing (IS) and Vendor Managed Inventory (VMI). The VMI is a coordination mechanism where the supplier is responsible for the inventory management of his customer. This mechanism is based on several principles, including developed information sharing between involved parties. The use of IS and VMI allow companies to increase profits and reduce costs. However, the results about the benefits from their use remain not clear. This motivates the need for new assessments and a better understanding of their effects. This thesis main contribution lies in the analysis and comprehension of IS and VMI’s impacts on supply chains. Especially, we address the issue of supply chains where tiers are production companies with different effectiveness levels. The examined scenario is based on a three tiers supply chain where each tier can belong to four effectiveness classes. The supply chain can respond to two types of end market demands: stable demands or fluctuant demands. In addition, several coordination mechanisms are studied: (i) standard management mechanism, (ii) information sharing between two enterprises, (iii) information sharing between three enterprises, (iv) VMI and (v) Extended VMI to all the three enterprises. The tool used to conduct these experiments is the discrete event simulation software “Arena”. The interpretation of the results showed that the IS coordination mechanism has not very significant improvement. Indeed, as companies have finite capacity, the availability of information did not yield better results. Whereas, the VMI could achieve reductions in both inventory and supply chain costs. In addition, VMI improved profits of the two parties, the vendor and the customer. Finally, the advantages of VMI appear to be stronger when the overall supply chain is less effective.

No presente trabalho é proposto um modelo de simulação de uma cadeia de suprimentos integrada com adoção da estratégia de VMI (Vendor Managed Inventory) entre uma empresa do setor de minério de ferro e alguns de seus fornecedores estratégicos. O modelo baseia-se em uma estrutura de avaliação de sistemas VMI adaptada de Sarpola et al. (2007) em conjunto com as configurações de cadeias de suprimentos propostas por Holmström et al (2003), o que permite medir o desempenho da cadeia de suprimentos segundo 3 níveis de integração. É feita uma revisão bibliográfica dos conceitos da estratégia de VMI, políticas de estoque em sistemas integrados, compartilhamento e grau de visibilidade de informações ao longo da cadeia de suprimentos. Os resultados obtidos possibilitam realizar uma análise quantitativa dos benefícios do VMI, onde são considerados demanda estocástica, lead time aleatório, produtos com características diferentes, compartilhamento de informações, visibilidade parcial da cadeia de suprimentos, lotes variáveis, cálculo dos estoques de segurança considerando informações dos pedidos, demanda real do cliente e erros de previsão. / In this paper we proposed a simulation model of an integrated supply chain with the adoption of VMI (Vendor Managed Inventory) strategy between a company of the iron ore and some of its strategic suppliers. The model is based on a framework for evaluating VMI systems adapted from Sarpola et al. (2007) together with the configurations of supply chains proposed by Holmström et al (2003), which measures the performance of the supply chain using 3 levels of integration. It is a literature review of the concepts of the strategy of VMI, inventory policies in integrated systems, sharing and degree of visibility of information throughout the supply chain. The results allowed to perform a quantitative analysis of the benefits of VMI, which are considered as stochastic demand, random lead time, products with different characteristics, information sharing, partial visibility of the supply chain, lots of variables, calculation of safety stocks based on information from client orders, actual customer demand and forecasting errors.

O processo de automatização de teste de software possui alto custo envolvido em sistemas de larga escala, pois exigem cenários de teste complexos e tempos de execução extremamente longos. Além disso, cada etapa do processo de teste requer recursos computacionais e um tempo considerável para a execução de muitos casos de teste, tornando-se um gargalo para as empresas de Tecnologia da Informação (TI). Neste contexto, os benefícios e oportunidades oferecidos pela combinação da computação em nuvem com o Teste como Serviço (Testing as a Service, TaaS), que é considerado um novo modelo de negócio e de serviço atraente e promissor, podem proporcionar um impacto positivo na redução do tempo de execução dos testes de maneira custo-efetiva e aumentar o retorno sobre o investimento ou Return on investment (ROI). Todavia, existe o problema de vendor lock-in, que é o aprisionamento do usuário à plataforma de um fornecedor específico ou serviço de teste, ocasionado pela dificuldade de migrar de um fornecedor TaaS para outro, limitando a utilização dessas novas tecnologias de maneira efetiva e eficiente, impedindo assim, a ampla adoção do TaaS. Como os estudos existentes não são rigorosos ou conclusivos e, principalmente, devido à falta de evidência empírica na área de serviço de teste, muitas questões devem ser investigadas na perspectiva da migração entre os provedores de TaaS. O objetivo deste trabalho é reduzir o impacto ocasionado pelo problema de vendor lock-in no processo de automatização de testes na computação em nuvem, na escrita, configuração, execução e gerenciamento dos resultados de testes automatizados. Neste contexto, foi desenvolvido o protótipo da abordagem intitulada Multi-TaaS por meio de uma biblioteca Java como prova de conceito. A abordagem Multi-TaaS é uma camada de abstração e a sua arquitetura permite abstrair e flexibilizar a troca de fornecedores de TaaS de forma portável, pois permite encapsular toda a complexidade da implementação do engenheiro de software ao desacoplar o teste automatizado de qual plataforma TaaS ele será executado, bem como abstrair os aspectos da comunicação e integração entre as APIs REST proprietárias dos diferentes fornecedores de TaaS. Além disso, a abordagem Multi-TaaS possibilita também sumarizar os resultados dos testes automatizados de forma independente das tecnologias da plataforma TaaS subjacente. Foram realizadas avaliações comparativas da eficiência, efetividade, dificuldade e do esforço de migração entre as abordagens Multi-TaaS e abordagem convencional, por meio de experimentos controlados. Os resultados deste trabalho indicam que a nova abordagem permite facilitar a troca do serviço de teste, melhorar a eficiência e, principalmente, reduzir o esforço e os custos de manutenção na migração entre fornecedores de TaaS. Os estudos realizados no experimento controlado são promissores e podem auxiliar os engenheiros de software na tomada de decisão quanto aos riscos associados ao vendor lock-in no TaaS. Por fim, a abordagem Multi-TaaS contribui, principalmente, para a portabilidade dos testes automatizados na nuvem e da sumarização dos resultados dos testes e, consequentemente, possibilita que o modelo de serviço TaaS na computação em nuvem seja amplamente adotado, de forma consciente, no futuro. / The automation of software testing involves high costs in large-scale systems, since it requires complex test scenarios and extremely long execution times. Moreover, each of its steps demands computational resources and considerable time for running many test cases, which makes it a bottleneck for Information Technology (IT) companies. The benefits and opportunities offered by the combination of cloud computing and Testing as a Service (TaaS), considered a new business and service model, can reduce the execution time of tests in a cost-effective way and improve Return on Investment (ROI). However, the lock-in problem, i.e., the imprisonment of the user in the platform of a specific vendor or test service caused by the difficult migration from one TaaS provider to another limits the effective use of such new technologies and prevents the widespread adoption of TaaS. As studies conducted are neither rigorous, nor conclusive, and mainly due to the lack of empirical evidence, many issues must be investigated from the perspective of migration among TaaS providers. This research aims at reductions in the impact of the vendor lock-in problem on the automation process of testing in cloud computing, writing, configuration, execution and management of automated test results. The prototype of the Multi- TaaS approach was developed through a Java library as a proof of concept. The Multi-TaaS approach is an abstraction layer and its architecture enables the abstraction and flexibilization of the exchange of TaaS providers in a portable way, once the complexity of the software engineers implementation can be encapsulated. The two main advantages of Multi-TaaS are the decoupling of the automated test from the TaaS platform on which it will be executed and the abstraction of the communication and integration aspects among the proprietary REST APIs of the different TaaS providers. The approach also enables the summarization of automated test results independently of the underlying TaaS platform technologies. A comparative evaluation between Multi-TaaS and conventional migration approaches regarding the difficulty, efficiency, effectiveness and effort of migration among TaaS providers was conducted through controlled experiments.The results show the approach facilitates the exchange of test service, improves efficiency and reduces the effort and maintenance costs of migration among TaaS providers. The studies conducted in the controlled experiment are promising and can assist software engineers in decision-making regarding the risks associated with vendor lock-in in TaaS. The Multi-TaaS approach contributes mainly to the portability of automated tests in the cloud and summarization of their results. Finally, this research enables also the widespread adoption of the TaaS service model in cloud computing, consciously, in the future.

Value-added tax (VAT) was introduced in South Africa in 1991 by the Value-Added Tax Act (89 of 1991) (the VAT Act). The South African VAT system is a destination-based, consumption-type VAT and is levied on goods or services consumed in South Africa. The definition of enterprise is an important definition in the VAT Act and it sets out the persons, activities and supplies that are to be included in the VAT base. It is compulsory for a person that conducts an enterprise in South Africa to register for VAT if the threshold set for taxable supplies is exceeded. There are interpretational problems and uncertainties in respect of the definition of “enterprise” and when an enterprise is conducted in South Africa or partly in South Africa. The purpose of this research study was to interpret the term enterprise for South African VAT purposes, to identify interpretational challenges and uncertainties and to suggest what must be addressed through guidance and interpretation by the South African Revenue Service (SARS) to provide more clarity. The research methodology followed to achieve the set objectives was normative research which is a form of legal research, specifically doctrinal. The requirements in terms of the VAT Act for levying of VAT, registration for VAT and the conducting of an enterprise in South Africa were explored and interpretational challenges and uncertainties were identified. The requirements for levying of and registration for VAT/ GST, in New Zealand, in terms of information supplied by the EU and guidance supplied in respect thereof by the OECD were analysed and discussed. The information obtained was used to establish how the interpretational problems and uncertainties that were identified are dealt with in New Zealand and in terms of the information and guidance from the EU and the OECD. The interpretational challenges and uncertainties identified include the reference in the definition of enterprise in Section 1(1) of the VAT Act to activities that must be conducted continuously or regularly in South Africa or partly in South Africa. Uncertainty as to the interpretation of the term “utilised or consumed in the Republic” also exists. Guidance in respect of these interpretational problems and uncertainties is necessary to enable suppliers and consumers to determine with certainty if a person is obliged to register for and levy VAT on supplies made in South Africa. / MCom (South African and International Tax) ,North-West University, Potchefstroom Campus, 2015