Vertical handovers as adaption methods in pervasive systems

Pervasive systems need to be context aware and need to adapt to context changes, including network disconnections and changes in network Quality of Service (QoS). Vertical handover (handover between heterogeneous networks) is one of possible adaptation methods. It allows users to roam freely between heterogeneous networks while maintaining continuity of their applications. This paper proposes a vertical handover approach suitable for multimedia applications in pervasive systems. It describes the adaptability decision making process which uses vertical handovers to support users mobility and provision of QoS suitable for users’ applications. The process evaluates context information regarding user devices, User location, network environment, and user perceived QoS of applications.

Stability and cycles in a cobweb model with heterogeneous expectations

We investigate the dynamics of a cobweb model with heterogeneous beliefs, generalizing the example of Brock and Hommes (1997). We examine situations where the agents form expectations by using either rational expectations, or a type of adaptive expectations with limited memory defined from the last two prices. We specify conditions that generate cycles. These conditions depend on a set of factors that includes the intensity of switching between beliefs and the adaption parameter. We show that both Flip bifurcation and Neimark-Sacker bifurcation can occur as primary bifurcation when the steady state is unstable.

Do adaptors and innovators subscribe to opposing values?

Many studies reveal that adaptors are more ready to accept the status quo, whereas innovators are less likely to do so. This raises the question: Do adaptors and innovators subscribe to opposing values? A study is conducted with the following hypotheses. H1 predicts that adaptors are more likely to subscribe to CONSERVATION values like security, conformity, and tradition. H2 predicts that innovators are more likely to subscribe to OPENNESS TO CHANGE values like self-direction and stimulation. The respondents consisted of 243 students from Singapore with an average age of 17.9 years and 195 students from Australia with an average age of 19.1 years. These respondents answered a survey that contained the Kirton Adaption-Innovation (KAI) inventory and the Schwartz value survey. For the Singapore sample, KAI was negatively correlated with CONSERVATION: r = -39, p <.0001; but it was positively correlated with OPENNESS TO CHANGE: r = .14, p <.05. For the Australian sample, KAI was negatively correlated with CONSERVATION: r = -.15, p <.05; but it was positively correlated with OPENNESS TO CHANGE: r =.32, p <.0001. A standard regression analysis indicated that CONSERVATION was the most significant predictor (P = -.43, p <.0001) of KAI, followed by OPENNESS TO CHANGE (P =.37, p <.0001) and Nationality (P =.21, p <.0001). The significant finding associated with Nationality could be attributed to the fact that the Singaporean respondents were a highly select and innovative group of individuals who were aspiring to work in the media industry.

Automated layout of small lattices using layer diagrams

Good quality concept lattice drawings are required to effectively communicate logical structure in Formal Concept Analysis. Data analysis frameworks such as the Toscana System use manually arranged concept lattices to avoid the problem of automatically producing high quality lattices. This limits Toscana systems to a finite number of concept lattices that have been prepared a priori. To extend the use of formal concept analysis, automated techniques are required that can produce high quality concept lattice drawings on demand. This paper proposes and evaluates an adaption of layer diagrams to improve automated lattice drawing. © Springer-Verlag Berlin Heidelberg 2006.