Kevin Chalmers

The Design Space of Temporal Graph Visualisation

This paper presents our work in mapping the design space of techniques for temporal graph visualisation. We identify two independent dimensions upon which the techniques can be classified: graph structural encoding and temporal encoding. Based on these dimensions, we create a matrix into which we organise existing techniques. We identify gaps in this design space which may prove interesting opportunities for the development of novel techniques. We also consider additional dimensions on which further useful classification could be made. In organising the disparate existing approaches from a wide range of domains, our classification will assist those new to the research area, and designers and evaluators developing systems for temporal graph data by raising awareness of the range of possible approaches available, and highlighting possible directions for further research.

Visual Techniques to Support Exploratory Analysis of Temporal Graph Data

Recently, much research has focused on developing techniques for the visual representation of temporal graph data. This paper takes a wider look at the visual techniques involved in exploratory analysis of such data, considering the variety of sub tasks and contextual tasks required to understand change in a graph over time, and the visual techniques which are able to support these tasks. In so doing, we highlight a number of tasks which are less well supported by existing techniques, which could prove worthwhile avenues for future research.

Semantic description of cloud service agreements

To provide cloud services as a utility there must be a mechanism for comprehensively and precisely specifying cloud service agreements to reduce differences in service perception between customers and suppliers. This paper proposes a description logic driven approach to specifying cloud service agreements as ontology, which allows agreement and negotiation between the parties in the service agreement. A unique contribution is provided by modelling of cloud service agreements as ontology which is precise and comprehensive. Future work sees the approach expanded to include a greater number of cloud service agreement artifacts and a service agreement specification for a financial calculation service.

Benefits Management of Cloud Computing Investments

This paper examines investments in cloud computing using the Benefits Management approach. The major contribution of the paper is to provide a unique insight into how organizations derive value from cloud computing investments. The motivation for writing this paper is to consider the business benefits generated from utilizing cloud computing in a range of organizations. Case studies are used to describe a number of organizations approaches to benefits exploitation using cloud computing. It was found that smaller organizations can generate rapid growth using strategies based on cloud computing. Larger organizations have used utility approaches to reduce the costs of IT infrastructure.

Evolution Feature Oriented Model Driven Product Line Engineering Approach for Synergistic and Dynamic Service Evolution in Clouds:Four Kinds of Schema☆

The proposed research will focus on developing a novel approach to solve Software Service Evolution problems in Computing Clouds. The approach will support dynamic evolution of the software service in clouds via a set of discovered evolution patterns. An initial survey informed us that such an approach does not exist yet and is in urgent need. Evolution Requirement can be classified into evolution features; researchers can describe the whole requirement by using evolution feature typology, the typology will define the relation and dependency between each features. After the evolution feature typology has been constructed, evolution model will be created to make the evolution more specific. Aspect oriented approach can be used for enhance evolution feature-model modularity. Aspect template code generation technique will be used for model transformation in the end. Product Line Engineering contains all the essential components for driving the whole evolution process.

A Task Orientated Requirements Ontology for Cloud Computing Services

Requirements ontology offers a mechanism to map requirements for cloud computing services to cloud computing resources. Multiple stakeholders can capture and map knowledge in a flexible and efficient manner. The major contribution of the paper is the definition and development of an ontology for cloud computing requirements. The approach views each user requirement as a semantic intelligence task that maps and delivers it as cloud services. Requirements are modelled as tasks designed to meet specific requirements, problem domains that the requirements exist in, and problem-solving methods which are generic mechanisms to solve problems. A meta-ontology for cloud computing is developed and populated with ontology fragments on to which cloud computing requirements can be mapped. A critical analysis of the usage of ontologies in the requirements process is made and a case study is described that demonstrates the approach in a real-world application. The conclusion is that problem-solving ontologies provide a useful mechanism for the specification and reuse of requirements in the cloud computing environment.

Collaborative Diffusion on the GPU for Path-Finding in Games

Exploiting the powerful processing power available on the GPU in many machines, we investigate the performance of parallelised versions of pathfinding algorithms in typical game environments. We describe a parallel implementation of a collaborative diffusion algorithm that is shown to find short paths in real-time across a range of graph sizes and provide a comparison to the well known Dijkstra and A* algorithms. Although some trade-off of cost vs path-length is observed under specific environmental conditions, results show that it is a viable contender for pathfinding in typical real-time game scenarios, freeing up CPU computation for other aspects of game AI.

Poxels: polygonal voxel environment rendering

We present efficient rendering of opaque, sparse, voxel environments with data amplified in local graphics memory with stream-out from a geomery shader to a cached vertex buffer pool. We show that our Poxel rendering primitive aligns with optimized rasterization hardware and so results in high visual quality over ray casting methods. Lossless run length encoding of occlusion culled voxels and coordinate quantization further reduces host data transfers.

Towards Reducing Complexity of Multi-agent Simulations by Applying Model-Driven Techniques

Creating multi-agent simulations is a challenging task often requiring programming skills at the professional software developer level. Model driven methods of software development are an appropriate tool for reducing the complexity of the development process of such simulations. The modeller is relieved from implementing time consuming programming details and can concentrate on the application itself. We present the domain specific language Athos with which network based traffic simulations can be created declaratively. The models are platform independent and executable code can be generated for two popular multi-agent platforms. We use a simple yet illustrative example to show how Athos can be applied.

ATHOS - A Domain-Specific Language for Multi-agent Simulations

Creating multi-agent simulations is a challenging task often requiring programming skills at the professional developer level which domain experts scarcely possess. We present a model-driven approach that relieves agent experts from time-consuming, error-prone implementation tasks and allows them to focus on the application itself. With our domain specific language Athos, network-based traffic simulations can be created declaratively. The models are platform independent and executable code can be generated for two popular multi-agent platforms.