909 resultados para agent-based model


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In order to facilitate the development of agent-based software, several agent programming languages and architectures, have been created. Plans in these architectures are often self-contained procedures with an associated triggering event and a context condition, while any further information about the consequences of executing a plan is absent. However, agents designed using such an approach have limited flexibility at runtime, and rely on the designer’s ability to foresee all relevant situations an agent might have to handle. In order to overcome this limitation, we have created AgentSpeak(PL), an interpreter capable of performing state-space planning to generate new high-level plans. As the planning module creates new plans, the plan library is expanded, improving performance over time. However, for new plans to be useful in the long run, it is critical that the context condition associated with new plans is carefully generated. In this paper we describe a plan reuse technique aimed at improving an agent’s runtime performance by deriving optimal context conditions for new plans, allowing an agent to reuse generated plans as much as possible.

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Expressing contractual agreements electronically potentially allows agents to automatically perform functions surrounding contract use: establishment, fulfilment, renegotiation etc. For such automation to be used for real business concerns, there needs to be a high level of trust in the agent-based system. While there has been much research on simulating trust between agents, there are areas where such trust is harder to establish. In particular, contract proposals may come from parties that an agent has had no prior interaction with and, in competitive business-to-business environments, little reputation information may be available. In human practice, trust in a proposed contract is determined in part from the content of the proposal itself, and the similarity of the content to that of prior contracts, executed to varying degrees of success. In this paper, we argue that such analysis is also appropriate in automated systems, and to provide it we need systems to record salient details of prior contract use and algorithms for assessing proposals on their content. We use provenance technology to provide the former and detail algorithms for measuring contract success and similarity for the latter, applying them to an aerospace case study.

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This paper investigates the application of neural networks to the recognition of lubrication defects typical to an industrial cold forging process employed by fastener manufacturers. The accurate recognition of lubrication errors, such as coating not being applied properly or damaged during material handling, is very important to the quality of the final product in fastener manufacture. Lubrication errors lead to increased forging loads and premature tool failure, as well as to increased defect sorting and the re-processing of the coated rod. The lubrication coating provides a barrier between the work material and the die during the drawing operation; moreover it needs be sufficiently robust to remain on the wire during the transfer to the cold forging operation. In the cold forging operation the wire undergoes multi-stage deformation without the application of any additional lubrication. Four types of lubrication errors, typical to production of fasteners, were introduced to a set of sample rods, which were subsequently drawn under laboratory conditions. The drawing force was measured, from which a limited set of features was extracted. The neural network based model learned from these features is able to recognize all types of lubrication errors to a high accuracy. The overall accuracy of the neural network model is around 98% with almost uniform distribution of errors between all four errors and the normal condition.

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Although the development of geographic information system (GIS) technology and digital data manipulation techniques has enabled practitioners in the geographical and geophysical sciences to make more efficient use of resource information, many of the methods used in forming spatial prediction models are still inherently based on traditional techniques of map stacking in which layers of data are combined under the guidance of a theoretical domain model. This paper describes a data-driven approach by which Artificial Neural Networks (ANNs) can be trained to represent a function characterising the probability that an instance of a discrete event, such as the presence of a mineral deposit or the sighting of an endangered animal species, will occur over some grid element of the spatial area under consideration. A case study describes the application of the technique to the task of mineral prospectivity mapping in the Castlemaine region of Victoria using a range of geological, geophysical and geochemical input variables. Comparison of the maps produced using neural networks with maps produced using a density estimation-based technique demonstrates that the maps can reliably be interpreted as representing probabilities. However, while the neural network model and the density estimation-based model yield similar results under an appropriate choice of values for the respective parameters, the neural network approach has several advantages, especially in high dimensional input spaces.

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The knowledge needs and knowledge-related behaviours of receivers are among the most crucial, yet of ten overlooked, aspects of successful knowledge-sharing. This research examines how sharers consider receivers' knowledge needs and knowledge-related behaviours when choosing whether to share their knowledge and which channels to use for the transmission of that knowledge. A new theory of knowledge sharing - Receiver Theory - is introduced, and a receiver-based model of knowledge sharing is developed from existing literature. Two exploratory case studies are conducted using the model as a guiding framework. A key finding shows that perceived receiver knowledge needs and behaviours are Important motivators and inhibitors in sharer choices in intra-organisational knowledge sharing. This finding was suggested for both personalised and codified knowledge sharing strategies. The study suggests that for companies to realise more effective knowledge sharing, they should develop better ways to connect potential sharers with receivers' real knowledge needs. The study also suggests that sharing on a need-to know basis impedes change In organisational power structures and prevents the integration of isolated pockets of knowledge that may yield new value.

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The present work describes a hybrid modeling approach developed for predicting the flow behavior, recrystallization characteristics, and crystallographic texture evolution in a Fe-30 wt pct Ni austenitic model alloy subjected to hot plane strain compression. A series of compression tests were performed at temperatures between 850 °C and 1050 °C and strain rates between 0.1 and 10 s−1. The evolution of grain structure, crystallographic texture, and dislocation substructure was characterized in detail for a deformation temperature of 950 °C and strain rates of 0.1 and 10 s−1, using electron backscatter diffraction and transmission electron microscopy. The hybrid modeling method utilizes a combination of empirical, physically-based, and neuro-fuzzy models. The flow stress is described as a function of the applied variables of strain rate and temperature using an empirical model. The recrystallization behavior is predicted from the measured microstructural state variables of internal dislocation density, subgrain size, and misorientation between subgrains using a physically-based model. The texture evolution is modeled using artificial neural networks.

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In settings such as electronic markets where trading partners have conflicting interests and a desire to cooperate, mobile agent mediated negotiation have become very popular. However, agent-based negotiation in electronic commerce involves the exchange of critical and sensitive data that must be highly safeguarded. Therefore, in order to give benefits of quick and safe trading to the trading partners, an approach that secures the information exchanged between the mobile agents during e-Commerce negotiations is needed. To this end, we discuss an approach that we refer to as Multi-Agent Security NEgotiation Protocol (MASNEP). To show that MASNEP protocol is free of attacks and thus the information exchanged throughout electronic negotiation is truly secured, we provide a formal proof on the correctness of the MASNEP.

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We present an agent-based system Intelligent Financial News Digest System (IFNDS) for analyzing online financial news articles and associated material. The system can abstract, synthesize, digest, and classify the contents, and assesses whether the report is favorable to any company discussed in the reports. It integrates artificial intelligence technologies including traditional information retrieval and extraction techniques for the news analysis. It makes use of keyword statistics and backpropagation training data to identify companies named in reportage whether it is, evaluatively speaking, positive, negative or neutral. The system would be of use to media such as clipping services, media management, advertising, public relations, public interest, and e-commerce professionals and government non-governmental bodies interested in monitoring the media profiles of corporations, products, and issues.

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Middle agents play a very important role in multiagent systems used in open and dynamic environments. The performance of middle agents relies heavily on the matchmaking algorithms used. The actual performance of provider agents in accomplishing delegated tasks has a significant impact on the matchmaking outcomes of middle agents. With those observations in mind, this paper discusses the incorporation of the track records of agents in accomplishing delegated tasks into the matchmaking process. How to provide initial values for track records in the algorithm are detailed. A prototype is also built to verify the algorithm. Based on the improved algorithm, the matchmaking outcomes are more accurate and reasonable.

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'Easy to enrol, easy to vote' was the slogan devised by the New South Wales electoral office in the 1980s. How did this system evolve from a British based model to a distinctively Australian one?

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The problems of unsustainable development and the increased-awareness of corporate power in the global era have contributed to an agenda of corporate citizenship. This thesis explores the meanings and practices that fall under the banner of the triple bottom line of corporate citizenship through forty-two in-depth interviews with representatives from the corporate sector and NGO sector (including trade unions) in Australia. This purposive sample includes a specific range of corporate industries and NGO types, all of which have involvement with various areas of sustainability. Interviewees described their feelings and experiences in relation to the concept of the triple bottom line, the potential and limitations of this type of sustainability and the purpose and impacts of partnerships between NGOs and the corporate sector. On the basis of this research, this thesis argues that corporate citizenship is at best, a set of initiatives for making minor adjustments to the way companies perform their day-to-day operations and at worst, a program for improving corporate image rather than performance and for shifting the agenda of sustainable development toward corporate interests. While radical steps are required to achieve a sustainable society and environment, the terms of corporate citizenship offer very limited opportunities for change. The self-regulatory and market based model of citizenship does not challenge the impact of consumerism or the legitimacy of particular industry types and their products, except where threats are perceived to the longevity of the companies involved. Furthermore, while the exploitation of the environment and society has occurred as a result of corporate self-interest, corporate citizenship is justified on the same basis. The self-interest rationale and the tyranny of the economic bottom line in particular, substantially limit the fields of responsibility that can be included in the citizenship paradigm. While there are undoubtedly some well-intentioned corporate representatives who are working toward attaining a more sustainable corporate culture, the discourse is primarily used to shift the sustainable development agenda toward corporate paradigms and interests.

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♦ The comparison of disparate interventions for the prevention and management of osteoarthritis (OA) is limited by the quality and quantity of published efficacy studies and the use of disparate measures for reporting clinical trial outcomes.

♦ The “transfer to utility” technique was used to translate published trial outcomes into a health-related quality-of-life (utility) scale, creating a common metric which supported comparisons between disparate interventions.

♦ Total hip replacement (THR) and total knee replacement (TKR) surgery were the most effective treatments and also highly cost-effective, at estimated cost per quality-adjusted life-year (QALY) of $7500 for THR and $10 000 for TKR (best estimate).

♦ Other apparently highly cost-effective interventions were exercise and strength training for knee OA (< $5000/QALY), knee bracing, and use of capsaicin or glucosamine sulfate (< $10 000/QALY).

♦ The cost per QALY estimates of non-specific and COX-2 inhibitor non-steroidal anti-inflammatory drugs were affected by treatment-related deaths and highly sensitive to the discounting of life-years lost.

♦ OA interventions that have been shown to be ineffective (eg, arthroscopy) are targets for redistribution of healthcare resources.

♦ OA interventions which lack efficacy studies (eg, prevention programs) require further research to assist priority setting.

♦ The application of the Health-sector Wide model to OA demonstrates its role as an evidence-based model that can be successfully applied to identify marginal interventions — those to be expanded and contracted to reduce the expected burden of disease, within current healthcare resources.

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Challenges the existing normal science in project management with its limitations of high certainty in scope definition and develops a contingency based model for project / program management (PROJAM). The PROJAM concept is theoretically supported through the identification of eight inter related aspects - uncertainty, maturity, stakeholders, pareto, reward, transparency, partnering, and program management. The ideas presented represent a radical change to the eisting project management body of knowledge and expand the scope of project management to deal with complex projects / programs including organisational change, core function outsourcing (asset management) and IT hardware and software outsourcing.

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Composites containing saturated fluid are widely distributed in nature, such as saturated rocks, colloidal materials and biological cells. In the study to determine effective mechanical properties of fluid-saturated composites, a micromechanical model and a multi-scale homogenization-based model are developed. In the micromechanical model the internal fluid pressure is generated by applying eigenstrains in the domain of the fluid phase and the explicit expressions of effective bulk modulus and shear modulus are obtained. Meanwhile a multi-scale homogenization theory is employed to develop the homogenization-based model on determination of effective properties at the small scale in a unit cell level. Applying the two proposed approaches, the effects of the internal pressure of hydrostatic fluid on effective properties are further investigated.

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Provides a synthesis of human rights theory and human services practice and offers a rights based model to aid professional decision making and practice.