Showing papers on "Information sharing published in 1999"
TL;DR: In this paper, information flow between a supplier and a retailer in a two-echelon model that captures the capacitated setting of a typical supply chain is considered, and the authors estimate the savings at the supplier due to information flow and study when information is most beneficial.
Abstract: We incorporate information flow between a supplier and a retailer in a two-echelon model that captures the capacitated setting of a typical supply chain We consider three situations: (1) a traditional model where there is no information to the supplier prior to a demand to him except for past data; (2) the supplier knows the (s, S) policy used by the retailer as well as the end-item demand distribution; and (3) the supplier has full information about the state of the retailer Order up-to policies continue to be optimal for models with information flow for the finite horizon, the infinite horizon discounted and the infinite horizon average cost cases Study of these three models enables us to understand the relationships between capacity, inventory, and information at the supplier level, as well as how they are affected by the retailer's (S - s) values and end-item demand distribution We estimate the savings at the supplier due to information flow and study when information is most beneficial
932 citations
TL;DR: In this paper, the authors used data from 41 steel production lines to assess the effects of Japanese and U.S. human resource management (HRM) practices on worker productivity.
Abstract: This study uses personally collected data from 41 steel production lines to assess the effects of Japanese and U.S. human resource management (HRM) practices on worker productivity. The Japanese production lines employ a common system of HRM practices including: problem-solving teams, extensive orientation, training throughout employees' careers, extensive information sharing, rotation across jobs, employment security, and profit sharing. A majority of U.S. plants now have one or two features of this system of HRM practices, but only a minority have a comprehensive system of innovative work practices that parallels the full system of practices found among the Japanese manufacturers. We find that the Japanese lines are significantly more productive than the U.S. lines. However, U.S. manufacturers that have adopted a full system of innovative HRM practices patterned after the Japanese system achieve levels of productivity and quality equal to the performance of the Japanese manufacturers. This study's evidence helps reconcile conflicting views about the effectiveness of adopting Japanese-style worker involvement schemes in the United States. United States manufacturers that have adopted a definition of employee participation that extends only to problem-solving teams or information sharing do not see large improvements in productivity. However, U.S. manufacturers that adopt a broader definition of participation that mimics the full Japanese HRM system see substantial performance gains.
464 citations
TL;DR: The authors investigated the relationship between trust expectations, information quantity shared, the climate of trust, and negotiated outcomes, and found that negotiation effectiveness was associated with the quantity of information shared but not with trust.
Abstract: Trust expectations, information quantity shared, the climate of trust, and negotiated outcomes were investigated. Initial trust expectation was manipulated, and participants provided data about the quantity of information shared, the climate of trust, and the outcomes of the negotiations. The 324 participants were practicing managers who conducted a negotiating role play with win-win potential. Information sharing followed from initial trust expectations, and information sharing did not fully mediate the relationship between expectations and climate of trust. Negotiating effectiveness was associated with the quantity of information shared but not with trust. Procedural inefficiency (time to discover the solution) decreased as information quantity increased, but procedural inefficiency was not related to trust. One measure of outcome inefficiency (complexity of the agreement) decreased as trust increased, but another measure of outcome inefficiency (monetary cost of the agreement) was not related to trust....
367 citations
TL;DR: The authors found that bank lending is higher and proxies for default rates are lower in countries where lenders share information, regardless of the private or public nature of the information sharing mechanism, and also find that public intervention is more likely where private arrangements have not arisen spontaneously and creditor rights are poorly protected.
Abstract: Theory predicts that information sharing among lenders attenuates adverse selection and moral hazard, and can therefore increase lending and reduce default rates. To test these predictions, we construct a new international data set on private credit bureaus and public credit registers. We find that bank lending is higher and proxies for default rates are lower in countries where lenders share information, regardless of the private or public nature of the information sharing mechanism. We also find that public intervention is more likely where private arrangements have not arisen spontaneously and creditor rights are poorly protected.
224 citations
TL;DR: This paper examined cultural factors which may facilitate or impede the sharing of informal information in the context of face-to-face meetings in Chinese compared to Anglo-American organizations and found that individual differences, individual assertiveness, and corporate culture in influencing informal information sharing in Australia; and the trade-off between collective interests, respect for hierarchical status and concern with face in Taiwan.
Abstract: This study examines cultural factors which may facilitate or impede the sharing of informal information in the context of face-to-face meetings in Chinese compared to Anglo-American organizations. Both qualitative and quantitative data were collected through personally conducted interviews with middle level managers in a sample of Taiwanese and Australian manufacturing firms. The results suggest the importance of individual differences, individual assertiveness, and corporate culture in influencing informal information sharing in Australia; and the trade-off between collective interests, respect for hierarchical status and concern with face in Taiwan.
153 citations
TL;DR: The results show that higher networking flexibility in terms of price–time alternatives can be achieved when firms favor tight partnership relations, offering consequently a better scheduling performance.
150 citations
TL;DR: This paper examined the effects of group composition (i.e., member task-related knowledge and cognitive ability) on information sharing, conflict, and group decision effectiveness in a complex low-fidelity management simulation.
Abstract: This article examines the effects of group composition (i.e., member task-related knowledge and cognitive ability) on information sharing, conflict, and group decision effectiveness in a complex low-fidelity management simulation. Controversy within the group over the strategy to employ was strongly related to interpersonal conflict between members, whereas group-level indices of cognitive ability and task knowledge were the best predictors of decision-making effectiveness. As in past studies using relatively simple choice tasks, groups exhibited biased information sampling and generally failed to identify the best course of action suggested by their collective information. The discussion highlights the need for further research using theoretical models that incorporate both composition and process factors.
119 citations
TL;DR: A taxonomy based on institutional theory and six broad diffusion drivers that might be considered to sustain the implementation process of intranets are adapted and it seems that the critical drivers are knowledge building, subsidy and mobilization in the early stages of implementation.
Abstract: Intranets hold great promise as “organizational Internets” to allow information sharing and collaboration across departments, functions and different information systems within an organization. Yet not much is known about how to implement intranets. We adapt a taxonomy based on institutional theory and distinguish six broad diffusion drivers that might be considered to sustain the implementation process. An exploratory field study of four intranet implementations was conducted to analyze which drivers were used and the results that were yielded. We draw several conclusions. First, all six drivers were deployed in the analyzed cases. Second, the choice of drivers varied with the level of the intranet (corporate or unit), the implementation stage, and existing organizational practices and contingencies. Third, it seems that the critical drivers are knowledge building, subsidy and mobilization in the early stages of implementation. In the later stages knowledge deployment, subsidy and innovation directives were most commonly used.
83 citations
TL;DR: The impact of information sharing is identified by simulating order fulfillment in this supply chain type and it is found inventory costs can be reduced while maintaining acceptable order fulfillment cycle times.
Abstract: Current information technology (IT), such as extended intranets (extranets) utilizing the components of the World Wide Web (WWW), makes information sharing between global supply chain partners feasible. Given this, an important issue is: What impact does efficient information sharing have on supply chain order fulfillment performance (specifically cycle time and inventory costs)? In this study, we focus on divergent differentiation supply chains (commonly associated with industries such as fashion apparel). We identify the impact of information sharing by simulating order fulfillment in this supply chain type and find inventory costs can be reduced while maintaining acceptable order fulfillment cycle times. This is true because information, which provides the basis for enhanced coordination and reduced uncertainty, can substitute for inventory.
73 citations
TL;DR: The paper will present the perspective on the challenges and potential directions for using object-based information models in a new generation of AEC software systems intended to offer component-based open architecture for distributed collaboration.
51 citations
12 Oct 1999
TL;DR: In this article, a matching problem is used to evaluate the impact of information sharing in terms of quality improvement in a two-stage supply chain, as an example of an assembly process.
Abstract: With advances in information technologies (IT), the research and practice of supply-chain information sharing has a direct impact on the production scheduling and inventory control. However, few investigations focused on the impact of supply-chain information sharing on product and process quality. Furthermore, it is still not clear how and what information should be shared/used, and how to quantify the benefits of information sharing in terms of quality improvement. In this research, a "matching problem" is used to demonstrate the quality impact of information sharing. We quantify and compare the impacts of different information-sharing strategies on process and product quality, and indicate that real-time information sharing may lead to dramatic quality improvement for an assembly process, as an example of a two-stage supply chain. The proposed approach to evaluate information sharing in terms of quality improvement may be directly extended to a more complex supply chain.
TL;DR: In this paper, the authors report the authors' innovative work in the arena of constructing an Internet-based, global software engineering environment, which allows distributed networking, global access, platform independence, information sharing, and internationalization.
Abstract: Over the past two decades, researchers and tool vendors have introduced techniques and tools to improve software engineering processes. Most of these are host-centered systems with closed architectures, fixed database drivers, specific network requirements, and platform-dependent client and server software. These restrictions make sharing information difficult, complicate tool integration, and limit global user access from diversified software environments. These are the major obstacles in global software production. Today's Internet technology provides a powerful and cost-effective means of overcoming these obstacles. Internet technologies allow distributed networking, global access, platform independence, information sharing, and internationalization. The Internet provides a nearly ubiquitous communication infrastructure, enabling team members to connect to the development process easily. This article reports the authors' innovative work in the arena of constructing an Internet-based, global software engineering environment.
TL;DR: In this article, the authors study how self-interest mediates these conflicting forces and show that, when members' preferences differ, no person ever submits a report that allows perfect inference of his private information, but instead, equilibrium strategies are many-to-one mappings that transform continuous data into ordered ranks.
Abstract: Committees improve decisions by pooling independent information of members, but promote manipulation, obfuscation, and exaggeration of private evidence when members have conflicting preferences. We study how self-interest mediates these conflicting forces. When members' preferences differ, no person ever submits a report that allows perfect inference of his private information. Instead, equilibrium strategies are many-to-one mappings that transform continuous data into ordered ranks: voting procedures are the equilibrium methods of achieving a consensus in committees. Voting necessarily coarsens the transmission of information among members, but is necessary to control conflicts of interest. The degree of coarseness of the equilibrium voting procedure is determined by the extent of conflicting preferences. Though self-interests necessarily reduce the efficient use of information in committees, real information sharing occurs nonetheless. Committees make better decisions on behalf of the average' (Pareto weighted) member than would any individual on the basis of own information. Committees are viable, though imperfect ways of making decisions when information is dispersed among members.
TL;DR: The issues of information sharing, information overload, and organizational memory are addressed by first describing the concepts of knowledge networks, then the conceptual architecture of a knowledge network to support a work group is presented.
Abstract: Recent strides in computing and telecommunications have provided managers with access to ever increasing amounts of data through higher speed computers and extensive connectivity. However, these advances have not solved the problems of getting the right information to the right person at the right time, and retaining that information in the organization for future use. This paper addresses the issues of information sharing, information overload, and organizational memory by first describing the concepts of knowledge networks. Then the conceptual architecture of a knowledge network to support a work group is presented. This is followed by a description of experiences encountered implementing a specific system for two new product concurrent engineering teams. Results of the implementation indicate that participants were quite satisfied with the new system.
TL;DR: An Internet-based model was developed to enhance information sharing and access on construction projects based on a single repository of all project databases residing on the project main server which is accessible using Internet and Web related technologies.
Abstract: The construction industry is an intensive information processing industry. Historically, there have always been problems in exchanging information between the various project participants. A comprehensive literature review highlighted the difficulties and problems with present information systems. An Internet-based model was developed to enhance information sharing and access on construction projects. The model is based on a single repository of all project databases residing on the project main server which is accessible using Internet and Web related technologies.
01 Jan 1999
TL;DR: The IFCs are developed by the International Alliance for Interoperability (IAI) and are general models of a building project that support project information sharing and exchange among different types of computer applications used in the project.
Abstract: Industry Foundation Classes (IFCs) developed by the International Alliance
for Interoperability (IAI) are general models of a building project that
support project information sharing and exchange among different types of
computer applications used in the project. The IFCs are developed based on
the information requirements from industry processes. The Project
Management Domain Committee of IAI's North America Chapter has
developed process models of cost estimating, scheduling, and their
integration for the purpose of generating the IFCs to support data sharing
throughout estimating and scheduling applications. The goal of this paper is
to present the models relevant to estimating and scheduling in the IFCs.
The paper discusses various modelling issues covering subjects such as
costs, construction processes, resources, products, and project documents
for work plans and cost estimates.
01 Jan 1999
TL;DR: The industrial supplier-customer relations have undergone radical changes in recent years as the philosophy behind managing manufacturing systems continues to be influenced by several Japanese manufacturing practices as mentioned in this paper, which has resulted in a certain level of co-operation, mainly in the areas of supply contracts and information sharing, that was lacking before.
Abstract: The industrial supplier-customer relations have undergone radical changes in recent years as the philosophy behind managing manufacturing systems continues to be influenced by several Japanese manufacturing practices. As more organizations realize that successful in-house implementation of Just-In-Time alone will have limited effect, they are seeking other members of their supply chain to change their operations. This has resulted in a certain level of co-operation, mainly in the areas of supply contracts and information sharing, that was lacking before. This is especially true when dealing with customized products, and is most commonly seen between suppliers and their larger customers.
12 Dec 1999
TL;DR: Results present a preliminary evaluation of characteristics of the "typical" student's network in these classes, including the size of the network, the frequency of exchanges, and the media used, and its relation to students sense of belonging to the class.
Abstract: Collaborative learning requires interaction and exchange among learners as they share experiences and solve problems cooperatively. In computer-supported distance learning classes it is often difficult to know to what extent individuals are interacting and how much they communicate with other class members. To explore intra-class interaction, social network data were gathered on the exchange of information and advice about class work among members of four distance learning classes, and the use of media for this exchange. Results present a preliminary evaluation of characteristics of the "typical" student's network in these classes, including the size of the network, the frequency of exchanges, and the media used, and its relation to students sense of belonging to the class.
TL;DR: In this article, the authors use a series of laboratory duopoly markets to examine the impact of demand uncertainty on sellers' output choices, and show that the influence of information sharing in facilitating tacit collusion can be quantified.
Abstract: I. INTRODUCTION Economists have long believed that enhanced information about demand conditions or rival actions can play an important role in facilitating collusion, for example because it simplifies detection of chiselers (Stigler [1964]). An extensive theoretical literature examines the incentives for non-cooperative firms to share information through a trade association about some uncertain parameter (see Sakai [1990; 1991] for a survey). Firms in these models may "cooperate" by sharing information in the trade association, even though most authors assume that the firms choose non-cooperative strategies in the product market. Under these conditions, Vives [1984] shows that with demand uncertainty, substitute goods and quantity competition, each firm's dominant strategy is to conceal information from its rivals. Therefore, under these conditions non-cooperative firms will not find it in their interests to form an information-sharing arrangement such as a trade association. Because non-cooperative firms should not wish to share information, Clarke [1983, 392] concludes that "information-pooling mechanisms like trade associations can be considered prima facie evidence that firms are illegally cooperating to restrict output." However, Kirby [1988] shows that non-cooperative firms will want to share information if cost functions are sufficiently quadratic. Moreover, Hviid [1989] demonstrates that non-cooperative firms will prefer to share information if they are sufficiently risk averse. These models typically assume that firms interact once and identify the static, subgame perfect Nash Equilibrium (NE) of the two-stage information sharing game. This is sensible when the goal is to focus on a narrow set of non-cooperative equilibria, because the set of non-cooperative equilibria becomes very large in these models in the more complex repeated game. However, repeated interaction between competing firms seems more relevant for empirical applications, especially for providing policy insight for trade associations that permit long-term interactions among firms. Unfortunately, empirical work in this area based on field data is challenging because the information different decision-makers possess, and the corresponding residual uncertainty they face, are typically difficult to identify. This paper uses a different empirical approach. We use a series of laboratory duopoly markets to examine the impact of demand uncertainty on sellers' output choices. Specifically, we examine the importance of information sharing in facilitating tacit collusion under conditions of demand uncertainty.(1) Our experiment employs repeated interaction between fixed pairs of subjects, trading the ability to directly test the static models for a more realistic, policy-relevant study of outcomes in the repeated game.(2) Our results indicate the extent to which results from static theory carry over to the repeated environment, and can help guide future theory for dynamic oligopoly models of information sharing. The experiment includes four distinct treatment conditions. In the primary treatment, sellers face uncertain demand but can eliminate uncertainty through voluntary, mutual information sharing. Three control treatments identify the reasons for voluntary information sharing and determine if it leads to more collusive outcomes. The first two control treatments eliminate sellers' information sharing opportunities. In the first control treatment sellers always remain uncertain about demand when choosing output, while in the second control treatment sellers always have perfect demand information. We refer to these control treatments respectively as Forced No Sharing and Forced Sharing throughout the paper. The third control treatment sharply reduces collusion incentives by truncating demand while still allowing voluntary information transmission. We refer to this control treatment as the Truncated Demand treatment. The results, briefly stated, are as follows. …
TL;DR: In this article, the effect of capital structure decisions on the incentives for firms in a duopoly to share information through a trade association was studied, and it was shown that the standard result for all-equity firms that information will not be shared may be reversed.
01 Aug 1999
TL;DR: An information modeling process is described that describes how information models are used to define data requirements and how, in a practical application, information models enable information sharing and exchange.
Abstract: This paper describes an information modeling process. Furthermore, the paper describes how information models are used to define data requirements and how, in a practical application, information models enable information sharing and exchange. Several information modeling methodologies, modeling, languages, and implementation methods are reviewed. Recommendations on building practical information models are presented. In addition, a possible set of data interfaces that support the data exchange and data sharing between life-cycle applications used in manufacturing industries is identified.
TL;DR: In an international context, national cultures will have different effects on social process as discussed by the authors, and the attitudes of managers towards aspects of decision making in their organizations, and their own behaviour, characterise the social process.
Abstract: If participation is to be a reality, the institution of appropriate structures is not enough ‐ the social processes within these must also facilitate power sharing. In an international context, national cultures will have different effects on social process. The attitudes of managers towards aspects of decision making in their organizations, and their own behaviour, characterise the social process. Organizational characteristics concerning information sharing and manipulation, decision style, and the role of IT, and personal behaviour involving information control, flexibility, and role playing, are considered for their impact on particpative decision making. A comparison between French and British managers, drawn from an international study of decision making, illustrates the issue considered. While considerable similarities were found between the two cultural groups, differences of degree as well as opposed views were also found. Overall attitudes were fairly favourable to particpation, but limitations were found, and these differed between the two groups.
27 Oct 1999
TL;DR: In this chapter, the main information management requirements for the VE network are identified and the federated support environmental mechanisms are addressed.
Abstract: In VE collaborations, many issues related to information management requirements become crucial, such as the privacy enforcement, information access rights, enterprise visibility levels, data redundancy control, and location transparency aspects. Analysis of the information management requirements in the VE environment lead to a federated information management approach, as the comprehensive support environment for effective information sharing among VE enterprises. In this chapter, the main information management requirements for the VE network are identified and the federated support environmental mechanisms are addressed.
23 Mar 1999
TL;DR: A prototype document warehouse system is described, which supports management of simple and compound documents, keyword-based and content-based retrieval, rule-based classification, SOM-based clustering, and XML data query and view rules.
Abstract: Nowadays, structured data such as sales and business forms are stored in data warehouses for decision makers to use. Further, unstructured data such as emails, HTML texts, images, videos, and office documents are increasingly accumulated in personal computer storage due to spread of mailing, WWW, and word processing. Such unstructured data, or what we call multimedia documents, are larger in volume than structured data and precious as corporate assets as well. So we need a document warehouse as a software framework where multimedia documents are analyzed and managed for corporate-wide information sharing and reuse like a data warehouse for structured data. We describe a prototype document warehouse system, which supports management of simple and compound documents, keyword-based and content-based retrieval, rule-based classification, SOM-based clustering, and XML data query and view rules.
TL;DR: A variety of approaches to educational use of the internet are reviewed, and they are divided into four categories: information delivery, information retrieval, information sharing, and technological samba schools.
Abstract: To date, popular enthusiasm for educational applications of computer networking has outpaced scholarly research on their educational value. This article reviews a variety of approaches to educational use of the internet, and divides them into four categories: information delivery, information retrieval, information sharing, and technological samba schools. The pedagogical foundations of each approach are analysed. As we move through these approaches in order, the emphasis shifts from information to ways of knowing, and there is an increasing emphasis on community.
Patent•
17 Sep 1999
TL;DR: In this article, a user registers disclosed information as disclosed information through the use of a register correcting part 3 and retrieves information through a retrieval presenting part 4 in the case of utilizing the disclosed information stored in an information storing part 1.
Abstract: PROBLEM TO BE SOLVED: To efficiently collect accurate evaluation with respect to disclosed information by selecting evaluation reference based on evaluation information up to the present time stored in a storing means when evaluation information is newly inputted. SOLUTION: A user registers disclosed information as the disclosed information through the use of a register correcting part 3 and retrieves information through the use of a retrieval presenting part 4 in the case of utilizing the disclosed information stored in an information storing part 1. Evaluation inputted by the user through the use of an evaluation input part and evaluation generated by an evaluation generating part 6 are stored in an evaluation storing part 2. When the user designates one of list-displayed the disclosed information to request the presentation of its contents, the part 4 presents the contents of the designated disclosed information. At the same time, an evaluation request part 7 requests the user to input the evaluation of the dimension if there is the dimension requiring input. Then, when the user inputs the significant evaluation, the evaluation is stored in the part.
TL;DR: Burns and Estache as discussed by the authors argue that information that regulators get from private operators of infrastructure monopolies should be used to make regulatory decisions more transparent and to reduce the risk of the private providers capturing the regulators.
Abstract: Information that private operators of infrastructure monopolies provide regulators can and should be used to address technical issues and monitor performance. But to reduce the risk of abusive behavior, the information should also be used to make both regulators and concessionaires accountable - for example, for passing any cost reductions along to consumers. Economists often characterize the regulation of monopolies as a game (between the regulator and the service provider) in which the two players do not share the same information. The regulator is assumed to have poorer information than the service provider about the scope of future efficiency gains and the size and timing of future investment plans. Over time, the regulator must increase its information base so that regulatory targets become more realistic - but this is a costly process. Burns and Estache examine the ways such information can and should be generated, especially through the accounting requirements a regulator can impose on private operators of infrastructure concessions. (They view concessioning and regulation as complementary, not substitute, activities.) Concessionaires should provide regulators with the information they need to: Compare outcomes with expectations. Evaluate the cost of adverse shocks that may warrant relaxed regulation. Evaluate whether lower costs than expected are the result of better performance or diminished output. Properly evaluate the asset base and charge for the consumption of capital. Information that regulators get from private operators of infrastructure monopolies should be used to make both regulators and concessionaires accountable. In Chile, for example, the privatization of monopolies led to significant efficiency gains, but it took a long time for these gains to be passed on to users because neither the firms nor the regulators were held accountable - until Congress expressed reluctance to endorse further privatization because earlier waves of privatization had not benefited consumers. In other words, information should be used to make regulatory decisions more transparent and to reduce the risk of the private providers capturing the regulators. This paper - a product of the Regulatory Reform and Private Enterprise Division, Economic Development Institute - is part of a larger effort in the institute to increase understanding of the importance of regulation for the success of infrastructure privatization.
12 Oct 1999
TL;DR: This paper investigates the approach of the multi-agents to coordinate the supply chain and proposes a constraint network model, which is proposed to model different managers with different operational management skills dynamically.
Abstract: Supply chain management is an important issue for manufacturing enterprises. The efficiencies of manufacturing enterprises depend on their logistic system. There is no doubt that information technology brings a lot of benefits to the supply chain's operation processes. It shortens lead times and decreases batch sizes, which leads to more efficient and effective order processing. Consequently, technological advances are necessary to keep a competitive advantage. As the availability of Internet technologies is increasing, managers can access online and real-time information. Different methods can be applied to utilize the information but not all the methods are suitable and create benefit to the supply chain management. We investigate the approach of the multi-agents to coordinate the supply chain. The contribution of this paper is summarized as follows: 1. A constraint network model is proposed to model different managers with different operational management skills dynamically. 2. As most of the operation processes are routine jobs, intelligent computer programs (agents) are utilized to replace such processes and reduce the operation cost tremendously. 3. Agents can model the operation processes and communicate through the Internet. This enables different warehouses and manufacturing plants to share the real time information. Therefore, better optimization can be achieved for the coordination of the supply chain. 4. Some possible value-added services such as a bullwhip detection agent and information sharing agent, which can extract useful information for the managers are also introduced.
01 Jan 1999
TL;DR: This paper identifies three types of project information integration approaches, document-based, schema-based and model-based; the characteristics of each type are reviewed and a comparative evaluation is presented.
Abstract: With the growing application of computers, the construction process is moving from a ‘paper based’ project execution to a future, fully computer based integrated environment that supports concurrent way of working. However, such a change will take a long time to complete. At present, several different integration technologies co-exist at different research and development (R&D) stages. This paper identifies three types of project information integration approaches, document-based, schema-based and model-based. The characteristics of each type of system are reviewed and a comparative evaluation is presented.