International Journal of Integrated Supply Management, 2007
ABSTRACT The research reported in this article is part of a larger project involving Enterprise R... more ABSTRACT The research reported in this article is part of a larger project involving Enterprise Resource Planning (ERP) adoption in Greece aiming at the investigation of the criteria that affect actual implementation. A structured questionnaire has been developed based on a combination of two frameworks: the first one is an extension proposed to the Markus and Tanis model, and the second one is based on a previously developed methodology (the six imperatives) for ERP evaluation, selection, and implementation. The paper discusses the frameworks, methodology, and preliminary findings from 40 companies of various industries. The results indicate a number of factors affecting ERP implementation and some differences in choices and activities between Small and Medium Sized Enterprises (SMEs) and larger companies concerning ERP adoption. One important finding is that many SMEs do not follow a structured methodology for ERP system implementation and they are not familiar with techniques such as business process reengineering and change management.
... approximately two thousand customers, is presented and solved by our heuristic, using an inte... more ... approximately two thousand customers, is presented and solved by our heuristic, using an interface to ... One can solve with success any of the two underlying sub-problems of the ... 20 Thus, a key determinant factor for obtaining good solutions for vehicle routing problems with tight ...
International Journal of Production Economics, 2008
The tendency of companies to expand their control through the entire supply chain is a significan... more The tendency of companies to expand their control through the entire supply chain is a significant managerial driver. On the other hand, large manufacturing and distribution firms have developed competences that do not cover all levels of the supply chain. In order to confront the lack of knowledge and expertise, enterprises can either outsource a specific operation or acquire a company that is specialized in the specific field. In this paper we focus on warehousing decisions and investigate three different warehousing policies and ownership structures of the warehousing facilities. The approach is based on game theory and an industrial example provides insight on the results reached.
ABSTRACT Increased competition and uncertainty characterise the new economy, introducing signific... more ABSTRACT Increased competition and uncertainty characterise the new economy, introducing significant pressures to supply chain participants, calling for capital investments only in value adding/revenue-generating assets. The tendency of companies to expand their control through the entire supply chain seems to attract significant managerial attention. On the other hand, large manufacturer and distributor firms have developed specific competences that do not expand to all the levels of the supply chain. In order to confront the lack of knowledge and expertise companies can either outsource the specific operation or acquire a company that is specialized in the specific field. In this paper we focus on warehousing decisions and investigate three different warehousing policies and ownership structures of the warehousing facilities.
We develop a model for lead-time quotation in a Markovian make-to-order production or service sys... more We develop a model for lead-time quotation in a Markovian make-to-order production or service system with strategic customers who exhibit risk aversion. Based on a CARA utility function of their net benefit, customers make individual decisions to join the system or balk by observing the state of the queue. The decisions of arriving customers result in a symmetric join/balk game. Regarding the firm's strategy, the provider announces a lead-time quotation for each state and a respective balking threshold. There is also a fixed entrance fee and compensation rate for the part of a customer' delay exceeding the quoted lead-time. Moreover, we consider the problem from the point of view of a social optimizer who maximizes the total net benefit of the system. We analyze the provider's and social optimizer's maximization problems and we consider two cases regarding the class of lead-time quotation policies, i.e., dynamic and single. We identify the optimal entrance thresholds...
We develop a model for lead-time quotation in a Markovian Make-To-Order production or service sys... more We develop a model for lead-time quotation in a Markovian Make-To-Order production or service system with strategic customers who exhibit risk aversion. Based on a CARA utility function of their net benefit, customers make individual decisions to join the system or balk by observing the state of the queue. The decisions of arriving customers result in a symmetric join/balk game. Regarding the firm’s strategy, the provider announces a lead-time quotation for each state and a respective balking threshold. There is also a fixed entrance fee and compensation rate for the part of a customer’ delay exceeding the quoted lead-time. Moreover, we consider the problem from the point of view of a social optimizer who maximizes the total net benefit of the system. We analyze the provider’s and social optimizer’s maximization problems and we consider two cases regarding the class of lead-time quotation policies, i.e., dynamic and single. We identify the optimal entrance thresholds in each case. F...
We develop and validate a model of the micro-level dynamics underlying the formation of macro-lev... more We develop and validate a model of the micro-level dynamics underlying the formation of macro-level information propagation patterns in online social networks. In particular, we address the dynamics at the level of the mechanism regulating a user's participation in an online information propagation process. We demonstrate that this mechanism can be realistically described by the dynamics of noisy spiking neurons driven by endogenous and exogenous, deterministic and stochastic stimuli representing the influence modulating one's intention to be an information spreader. Depending on the dynamically changing influence characteristics, time-varying propagation patterns emerge reflecting the temporal structure, strength, and signal-to-noise ratio characteristics of the stimulation driving the online users' information sharing activity. The proposed model constitutes an overarching, novel, and flexible approach to the modeling of the micro-level mechanisms whereby information propagates in online social networks. As such, it can be used for a comprehensive understanding of the online transmission of information, a process integral to the sociocultural evolution of modern societies. The proposed model is highly adaptable and suitable for the study of the propagation patterns of behavior, opinions, and innovations among others.
The management of supply chains is the current focus of corporate strategies. Currently, we note ... more The management of supply chains is the current focus of corporate strategies. Currently, we note that it is not businesses that compete but supply chains that compete. In order to lead in the corporate race, organisations take advantage of information and communication technologies for e-business. An executive level of strategic management of the supply chain is a requirement of which, one of the major ingredient is information that is passed among supply chain constituents. The information is generated, distributed, received and stored in supply chain management information systems of heterogeneous architectures and/or platforms. This poses a challenge in the sharing and understanding of the bits of information. In this paper we present an artificial intelligence approach for supply chain information systems that have heterogeneous architectures to share information through a common ontology. The supply chain ontology structures a shared formal specification of concepts and the rel...
International Journal of Integrated Supply Management, 2007
ABSTRACT The research reported in this article is part of a larger project involving Enterprise R... more ABSTRACT The research reported in this article is part of a larger project involving Enterprise Resource Planning (ERP) adoption in Greece aiming at the investigation of the criteria that affect actual implementation. A structured questionnaire has been developed based on a combination of two frameworks: the first one is an extension proposed to the Markus and Tanis model, and the second one is based on a previously developed methodology (the six imperatives) for ERP evaluation, selection, and implementation. The paper discusses the frameworks, methodology, and preliminary findings from 40 companies of various industries. The results indicate a number of factors affecting ERP implementation and some differences in choices and activities between Small and Medium Sized Enterprises (SMEs) and larger companies concerning ERP adoption. One important finding is that many SMEs do not follow a structured methodology for ERP system implementation and they are not familiar with techniques such as business process reengineering and change management.
... approximately two thousand customers, is presented and solved by our heuristic, using an inte... more ... approximately two thousand customers, is presented and solved by our heuristic, using an interface to ... One can solve with success any of the two underlying sub-problems of the ... 20 Thus, a key determinant factor for obtaining good solutions for vehicle routing problems with tight ...
International Journal of Production Economics, 2008
The tendency of companies to expand their control through the entire supply chain is a significan... more The tendency of companies to expand their control through the entire supply chain is a significant managerial driver. On the other hand, large manufacturing and distribution firms have developed competences that do not cover all levels of the supply chain. In order to confront the lack of knowledge and expertise, enterprises can either outsource a specific operation or acquire a company that is specialized in the specific field. In this paper we focus on warehousing decisions and investigate three different warehousing policies and ownership structures of the warehousing facilities. The approach is based on game theory and an industrial example provides insight on the results reached.
ABSTRACT Increased competition and uncertainty characterise the new economy, introducing signific... more ABSTRACT Increased competition and uncertainty characterise the new economy, introducing significant pressures to supply chain participants, calling for capital investments only in value adding/revenue-generating assets. The tendency of companies to expand their control through the entire supply chain seems to attract significant managerial attention. On the other hand, large manufacturer and distributor firms have developed specific competences that do not expand to all the levels of the supply chain. In order to confront the lack of knowledge and expertise companies can either outsource the specific operation or acquire a company that is specialized in the specific field. In this paper we focus on warehousing decisions and investigate three different warehousing policies and ownership structures of the warehousing facilities.
We develop a model for lead-time quotation in a Markovian make-to-order production or service sys... more We develop a model for lead-time quotation in a Markovian make-to-order production or service system with strategic customers who exhibit risk aversion. Based on a CARA utility function of their net benefit, customers make individual decisions to join the system or balk by observing the state of the queue. The decisions of arriving customers result in a symmetric join/balk game. Regarding the firm's strategy, the provider announces a lead-time quotation for each state and a respective balking threshold. There is also a fixed entrance fee and compensation rate for the part of a customer' delay exceeding the quoted lead-time. Moreover, we consider the problem from the point of view of a social optimizer who maximizes the total net benefit of the system. We analyze the provider's and social optimizer's maximization problems and we consider two cases regarding the class of lead-time quotation policies, i.e., dynamic and single. We identify the optimal entrance thresholds...
We develop a model for lead-time quotation in a Markovian Make-To-Order production or service sys... more We develop a model for lead-time quotation in a Markovian Make-To-Order production or service system with strategic customers who exhibit risk aversion. Based on a CARA utility function of their net benefit, customers make individual decisions to join the system or balk by observing the state of the queue. The decisions of arriving customers result in a symmetric join/balk game. Regarding the firm’s strategy, the provider announces a lead-time quotation for each state and a respective balking threshold. There is also a fixed entrance fee and compensation rate for the part of a customer’ delay exceeding the quoted lead-time. Moreover, we consider the problem from the point of view of a social optimizer who maximizes the total net benefit of the system. We analyze the provider’s and social optimizer’s maximization problems and we consider two cases regarding the class of lead-time quotation policies, i.e., dynamic and single. We identify the optimal entrance thresholds in each case. F...
We develop and validate a model of the micro-level dynamics underlying the formation of macro-lev... more We develop and validate a model of the micro-level dynamics underlying the formation of macro-level information propagation patterns in online social networks. In particular, we address the dynamics at the level of the mechanism regulating a user's participation in an online information propagation process. We demonstrate that this mechanism can be realistically described by the dynamics of noisy spiking neurons driven by endogenous and exogenous, deterministic and stochastic stimuli representing the influence modulating one's intention to be an information spreader. Depending on the dynamically changing influence characteristics, time-varying propagation patterns emerge reflecting the temporal structure, strength, and signal-to-noise ratio characteristics of the stimulation driving the online users' information sharing activity. The proposed model constitutes an overarching, novel, and flexible approach to the modeling of the micro-level mechanisms whereby information propagates in online social networks. As such, it can be used for a comprehensive understanding of the online transmission of information, a process integral to the sociocultural evolution of modern societies. The proposed model is highly adaptable and suitable for the study of the propagation patterns of behavior, opinions, and innovations among others.
The management of supply chains is the current focus of corporate strategies. Currently, we note ... more The management of supply chains is the current focus of corporate strategies. Currently, we note that it is not businesses that compete but supply chains that compete. In order to lead in the corporate race, organisations take advantage of information and communication technologies for e-business. An executive level of strategic management of the supply chain is a requirement of which, one of the major ingredient is information that is passed among supply chain constituents. The information is generated, distributed, received and stored in supply chain management information systems of heterogeneous architectures and/or platforms. This poses a challenge in the sharing and understanding of the bits of information. In this paper we present an artificial intelligence approach for supply chain information systems that have heterogeneous architectures to share information through a common ontology. The supply chain ontology structures a shared formal specification of concepts and the rel...
Increased competition and uncertainty characterise the new economy, introducing significant press... more Increased competition and uncertainty characterise the new economy, introducing significant pressures to supply chain participants, calling for capital investments only in value adding/revenue-generating assets. The tendency of companies to expand their control through the entire supply chain seems to attract significant managerial attention. On the other hand, large manufacturer and distributor firms have developed specific competences that do not expand to all the levels of the supply chain. In order to confront the lack of knowledge and expertise companies can either outsource the specific operation or acquire a company that is specialized in the specific field. In this paper we focus on warehousing decisions and investigate three different warehousing policies and ownership structures of the warehousing facilities. INTRODUCTION The new economy is characterised by increased uncertainty and intense competition. The continuously changing market needs and the increased competition in the global markets introduce significant pressures to supply chain participants. The tendency of companies to expand their control through the entire supply chain seems to attract significant managerial attention. On the other hand flexibility associated to the ability to respond to the challenges of the changing and dynamic economic environment is highlighted as the key feature in coping successfully with the uncertainty of the new economy. In this paper, under the above mentioned perspective, we focus on inventory and warehousing decisions and operations and investigate alternative warehousing policies accompanied with different ownership structures of the warehousing facilities. Since the seminal papers of Arrow et al. (1951) and Dvoretzky et al. (1952) inventory theory has been an active area of research attracting the interest of both academics and professionals. Significant research effort has been conducted to determine the optimal inventory policies. For example, Toktay and Wein (2001) focused on the base-stock policy incorporating forecast information to determine the base-stock level that minimizes the expected steady-state inventory holding and backorders costs, assuming stationary demand. Graves (1999) and Graves and Willems (2000) developed a framework for modeling strategic safety stock incorporating non-stationary demand. Meca et al. (2004) analysed situations where a collective of firms minimizes its joint inventory by means of information sharing and cooperation. Inventory theory has also been of great importance in supply chain management. Giannoccaro et al. (2003) defined a supply chain inventory management policy utilising fuzzy set theory to model uncertainty of demand and costs. Belvaux and Wolsey (2001) used mixed-integer programming in order to handle safety stocks in multilevel supply chains. Furthermore, in the context of supply chain, procedures that combine
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Papers by George Ioannou