Drawing OWL 2 ontologies with Eddy the editor

In this paper we introduce Eddy, a new open-source tool for the graphical editing of OWL~2 ontologies. Eddy is specifically designed for creating ontologies in Graphol, a completely visual ontology language that is equivalent to OWL~2. Thus, in Eddy ontologies are easily drawn as diagrams, rather than written as sets of formulas, as commonly happens in popular ontology design and engineering environments. This makes Eddy particularly suited for usage by people who are more familiar with diagramatic languages for conceptual modeling rather than with typical ontology formalisms, as is often required in non-academic and industrial contexts. Eddy provides intuitive functionalities for specifying Graphol diagrams, guarantees their syntactic correctness, and allows for exporting them in standard OWL 2 syntax. A user evaluation study we conducted shows that Eddy is perceived as an easy and intuitive tool for ontology specification

Visualization and user interactions in RDF data representation

The spreading of linked data in digital technologies creates the need to develop new approaches to handle this kind of data. The modern trends in the information technology encourage usage of human-friendly interfaces and graphical tools, which helps users to understand the system and speeds up the work processes. In this study my goal is to develop a set of best practices for solving the problem of visualizations and interactions with linked data and to create a working prototype based on this practices. My work is a part of a project developed by Fail-Safe IT Solutions Oy. During the research process I study various existing products that try to solve the problem of human-friendly interactions with linked data, compare them and based on the comparison develop my own approach for solving the problem in the given environment, which satisfies the provided specifications. The key findings of the research can be grouped in two categories. The first category of findings is based on the existing solution examinations and is related to the features I find beneficial to the project. The second category is based on the experience acquired during the project development and includes environment-specific and project-related findings

A bi-level model of dynamic traffic signal control with continuum approximation

This paper proposes a bi-level model for traffic network signal control, which is formulated as a dynamic Stackelberg game and solved as a mathematical program with equilibrium constraints (MPEC). The lower-level problem is a dynamic user equilibrium (DUE) with embedded dynamic network loading (DNL) sub-problem based on the LWR model (Lighthill and Whitham, 1955; Richards, 1956). The upper-level decision variables are (time-varying) signal green splits with the objective of minimizing network-wide travel cost. Unlike most existing literature which mainly use an on-and-off (binary) representation of the signal controls, we employ a continuum signal model recently proposed and analyzed in Han et al. (2014), which aims at describing and predicting the aggregate behavior that exists at signalized intersections without relying on distinct signal phases. Advantages of this continuum signal model include fewer integer variables, less restrictive constraints on the time steps, and higher decision resolution. It simplifies the modeling representation of large-scale urban traffic networks with the benefit of improved computational efficiency in simulation or optimization. We present, for the LWR-based DNL model that explicitly captures vehicle spillback, an in-depth study on the implementation of the continuum signal model, as its approximation accuracy depends on a number of factors and may deteriorate greatly under certain conditions. The proposed MPEC is solved on two test networks with three metaheuristic methods. Parallel computing is employed to significantly accelerate the solution procedure

Process Modeling for Simulation

This paper discusses shortfalls in relation to the requirements gathering phases of simulation. While many developments have taken place around supporting the model coding task of simulation, there are few tools available to assist in the requirements gathering phase. This is surprising as it has been reported by several researchers that the requirements phase can absorb twice as much resources as the coding phase. There are numerous process modeling tools available (over 100) that can and have been used to support the requirements phase of simulation. This paper provides a selective review of some of the most important in relation to simulation. A conclusion from this review is that none of the tools available adequately supports the requirements gathering phase of simulation. It is proposed that a process modeling tool be developed specifically to support simulation requirements gathering. The design objectives in the development of the tool are: (1) it should be capable of capturing a detailed description of a discrete event system; (2) it should have a low modeling burden and therefore be capable of being used by non-specialists; (3) it should present modeling information at a high semantic level so that manufacturing personnel can rationalize with it; (4) it should have good visualization capabilities; (5) it should support project teamwork. Based on these design objectives a proposed simulation process modeling tool called simulation activity diagrams (SAD) is presented