Showing papers on "Constraint graph (layout) published in 2017"

Towards Visualizing Big Data with Large-Scale Edge Constraint Graph Drawing

Abstract: Visualization plays an important role in enabling understanding of big data. Graphs are crucial tools for visual analytics of big data networks such as social, biological, traffic and security networks. Graph drawing has been intensively researched to enhance aesthetic features (i.e., layouts, symmetry, cross-free edges). Early physic-inspired techniques have focused on synthetic abstract graphs whose weights/distances of the edges are often ignored or assumed equal. Although recent approaches have been extended to sophisticated realistic networks, most are not designed to address very large-scale weighted graphs, which are important for visual analyses. The difficulty lies in the fact that the drawing process, governed by these physical properties, oscillates in large graphs and conflicts with specified distances leading to poor visual results. Our research attempts to alleviate these obstacles. This paper presents a simple graph visualization technique that aims to efficiently draw aesthetically pleasing large-scale straight-line weighted edge graphs. Our approach uses relevant physic-inspired techniques to promote aesthetic graphs and proposes a weak constraint-based approach to handle large-scale computing and competing goals to satisfy both weight requirements and aesthetic properties. The paper describes the approach along with experiments on both synthetic and real large-scale weighted graphs including that of over 10,000 nodes and comparisons with state-of-the-art approaches. The results obtained show enhanced and promising outcomes toward a general-purpose graph drawing technique for both big synthetic and real network data analytics.

Optimizing path real-time logic for unified real-time system

Abstract: By simply describing a classic weakly hard real-time system's performance with the number of tasks meeting or missing deadlines, the system's real-time characteristics cannot be expressed accurately and its reliability cannot be established. The path real-time logic (RTL) is used to determine the reliability of real-time systems; though desirable, it cannot be used as a tool to configure an optimized real-time system. This paper introduces the notion of optimizing path RTL, where integer constants of arithmetic inequality in path RTL are replaced by integer constants or integer variables. With further modifications, optimizing path RTL can not only determine the reliability of a real-time system, but also be used to optimize the system. Furthermore, a unified framework for hard, soft and weakly hard real-time system is established based on optimizing path RTL. The process of transforming a weakly hard real-time system into this unified framework is demonstrated. Moreover, this work proposes and proves a theorem that if the directed ring of a constraint graph contains all elements of behaviour specification (SP) and only SP, then its value must not be greater than zero. This theorem can be used to quickly determine the reliability and safety of a real-time system. A case study is presented to show the validity and reliability of optimizing path RTL and the unified real-time system.