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Journals
Kameni, E. (Eric) and Weide, Th.P. van der and Groot, W.T. (Wouter), Natural Model based Design in Context: an Effective Method for Environmental Problems. Complex Systems Informatics and Modeling Quarterly, No 12.5 (2017)
Analyzing complex problem domains is not easy. Simulation tools support decision makers to find the best policies. Model-based system development is an approach where a model of the application domain is the central driving force when designing simulation tools. State-of-the-art techniques however still require both expert knowledge of the application domain and the implementation techniques as provided by ICT (such as multilevel agent technology). Domain experts, however, usually do not master ICT sufficiently. Modeling is more insightful for the domain expert when its goal is to formalize the language being used in that domain as a semi-natural language. At the meta level, this language describes the main concepts of the type of application domain. The model then is a concretization of this meta model. The main focus of this article is (1) to propose a natural-language-based approach to modeling application domains, (2) to show how these models can be transformed systematically into computational models, and (3) to propose the tool TiC (Tool in Context) that supports the domain expert when developing a model and generating a simulation tool. Our research methodology is based on Design Science. We verify our approach by describing the various transformation steps in detail, and by demonstrating the way of working via a sample session applying a real problem of Laf Forest Reserve deforestation in North Cameroon.
Keywords: Actor Model; Multi-level Agent-based Model; Domain-specific Languages; Model Transformation; Environmental Problems
Khamis, M.M. and Weide, Th.P. van der, A Linguistic-Based Systematic Approach to Complex System Dynamics and its Application to E-government Introduction in Zanzibar. Complex Systems Informatics and Modeling Quarterly, No 11, 2017
System thinking has become an effective strategy when dealing with complex systems. Such systems are characterized by mutual interactions, causality and inter-dependency between system components. A typical example is the cooperation between governmental organizations and stakeholder interaction. The complexity of developing an e-government system suggests a more fundamental approach, where the roles of domain expert and system analyst are clearly separated. The main focus of this article is (1) to propose a linguistically-based systematic approach to the construction of models for the dynamics of complex systems, and (2) to propose extended causal diagrams. Our research methodology is based on Design Science. We start from a conceptual language developed for the application domain at hand and use this to define the dynamic factors. Then, we show how the resulting extended causal diagram is transformed into a framework for System Dynamics. We have demonstrated this approach by using a basic form of an e-Government as a running example. Our intention is to use this approach as a basis for a systematic step-wise introduction of e-Government in Zanzibar. Besides, this method is useful for modeling any complex system, especially for the description and evaluation of intended policies.
Keywords: Complex systems; conceptual modeling; system dynamics; extended causal diagram; model transformation; e-government introduction.
Khamis, M.M. and Weide, Th.P. van der, Conceptual Diagram Development for Sustainable e-Government Implementation. The Electronic Journal of e-Government, Volume 15 Issue 1 2017, pp 33-43
E-government implementation has received extra attention as a new way to increase the development of a country. International organizations such as the ITU and the United Nations provide strategic guidance to overcome the challenges of ICT use. Yet, the development of ICT use in developing countries is still very low. Researchers are contributing to support successful implementation with models and theories that conceptualize the complex situation. This paper extends the DPSIR-based e-government conceptual framework into the direction of implementation strategies.
The main focus is on improving stakeholder involvement during requirements engineering. Object Role Modeling (ORM) was used (1) to develop a semi-natural language (controlled language) that is understandable both for domain stakeholders and system analysts and (2) to make a common description of the application domain in this language. The proposed model can be used to construct quantitative simulation tools to be used by policy makers.
Keywords: Conceptual data modeling, Object Role Modeling, Manual service, Digital Service, DPSIR, Zanzibar.
Kameni, E. (Eric) and Weide, Th.P. van der, Intrusion Detection in a Trust-based Recommendation System. International Journal of Trust Management in Computing and Communications (IJTMCC), 2017
In multi-agent systems agents cooperate by asking other agent's opinions as part of their own decision making process. The goal of a recommendation system is to provide advice either on request or pro-actively. In this paper we assume that the value of an advice from another agent is determined by the trust in that other agent. We present a trust-based model of collaboration and decision making in a multi-agent system. We assume however that agents may be dishonest (such an agent is called an intruder), resulting in advices that may be false. The goal of this paper is the detection of intruders, thereby minimizing the damage that they can cause. We also present the underlying relational database model and use this to build a prototype. In our tests we show that the more influential an agent is in the multi-agent system, the faster that agent will be unmasked would it be an intruder.
Keywords: multi-agent system, trust, recommendation system, intrusion detection
Sulasikin A. (Andi) and Weide, Th.P. van der, Reputation, Impact and Relevance in Social Media. Journal of Technologies and Human Usability, Volume 12, Issue 3/4, 2017
Social Media are used for interaction between users via postings. Postings can have attached topics. Users may follow each other, or may express their special interest in special topics. Furthermore, users can comment on other postings or retweet them. As a consequence, postings will be on the so-called time line of some users, where the time line of a user indicates those postings that are visible to that user. These connections between users, postings, topics and time line can be used to define how influential users are, what the impact of a posting is , and how relevant a topic is. We extend an existing methodology. We define a model to capture the notions mentioned above, and derive a (recursive) system of equations that defines user influence, posting impact and topic relevancy in terms of each other. Then we present a solution for this set of equations, and a computational approach based on successive substitution.
Keywords: social media, reputation, impact, relevance