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On the accuracy of van der Waals inclusive density-functional theory exchange-correlation functionals for ice at ambient and high pressures
No full textDensity-functional theory (DFT) has been widely used to study water and ice for at least 20 years. However, the reliability of different DFT exchange-correlation (xc) functionals for water remains a matter of considerable debate. This is particularly true in light of the recent development of DFT based methods that account for van der Waals (vdW) dispersion forces. Here, we report a detailed study with several xc functionals (semi-local, hybrid, and vdW inclusive approaches) on ice Ih and six proton ordered phases of ice. Consistent with our previous study [B. Santra, J. Klimeš, D. Alfè, A. Tkatchenko, B. Slater, A. Michaelides, R. Car, and M. Scheffler, Phys. Rev. Lett. 107, 185701 (2011)] which showed that vdW forces become increasingly important at high pressures, we find here that all vdW inclusive methods considered improve the relative energies and transition pressures of the high-pressure ice phases compared to those obtained with semi-local or hybrid xc functionals. However, we also find that significant discrepancies between experiment and the vdW inclusive approaches remain in the cohesive properties of the various phases, causing certain phases to be absent from the phase diagram. Therefore, room for improvement in the description of water at ambient and high pressures remains and we suggest that because of the stern test the high pressure ice phases pose they should be used in future benchmark studies of simulation methods for water
Reconciling Versioning and Context in Hypermedia Structure Servers
No full textContextual structure servers and versioning servers share a similar goal in allowing different views on a stored structure according to the viewer’s perspective. In this paper we argue that a generic contextual model can be used to facilitate versioning. In order to prove our hypothesis we have drawn on our experiences with OHP-Version to extend FOHM’s contextual model
Requirements for In-Situ Authoring of Location Based Experiences
No full textIn this paper we describe an investigation into the requirements for and the use of in-situ authoring in the creation of location based pervasive and UbiComp experiences. We will focus on the co-design process with users that resulted in a novel visitor experience to a historic country estate. This has informed the design of new, in-situ, authoring tools supplemented with tools for retrospective revisiting and reorganization of content. An initial trial of these new tools will be discussed and conclusions drawn as to the appropriateness of such tools. Further enhancements as part of future trials will also be described
Semantic annotation in ubiquitous healthcare skills-based learning environments
No full textThis paper describes initial work on developing a semantic annotation system for the augmentation of skills-based learning for Healthcare. Scenario driven skills-based learning takes place in an augmented hospital ward simulation involving a patient simulator known as SimMan. The semantic annotation software enables real-time annotations of these simulations for debriefing of the students, student self study and better analysis of the learning approaches of mentors. A description of the developed system is provided with initial findings and future directions for the work.<br/
Exploring the Relationship Between FOHM and RDF
No full textOne of the results of the Open Hypermedia work of the last decade was the Fundamental Open Hypermedia Model (FOHM) capable of representing contextual structure from a variety of hypermedia domains. As the Semantic Web becomes more important it is interesting to compare its metadata language, the Resource Description Framework (RDF), with a model such as FOHM. In this paper we examine the relationship between FOHM and RDF to see if they have equivalent expressivity. In particular we look at whether you can represent FOHM structures in RDF, either as a direct mapping from FOHM to the RDF vocabulary or by defining a FOHM schema in RDFS or OWL
Design of experiments for models involving profile factors
No full textIn the traditional design of experiments, it is assumed that each run of the experiment involves the application of a treatment, consisting of static settings of the controllable factors. The objective of this work is to extend the usual optimal experimental design paradigm to modern experiments where the settings of factors are functions. Such factors are known as profile factors, or as dynamic factors. For these new experiments, the design problem is to identify optimal experimental conditions to vary the profile factors in each run of the experiment.In general, functions are infinite dimensional objects. The latter produces challenges in estimation and design. To face the challenges, a new methodology using basis functions is developed. Primary focus is given on the B-spline basis system, due to its computational efficiency and useful properties. The methodology is applied to a functional linear model, and expanded to a functional generalised linear model, reducing the problem to an optimisation of basis coefficients. Special cases, including combinations of profile and scalar factors, interactions, and polynomial effects, are taken into consideration.The methodology is demonstrated through multiple examples, aiming to find A- and D- optimal experimental designs. The sensitivity of optimal experimental conditions to changes in the settings of the profile factors and the functional parameters is extensively investigated. Bayesian optimal designs are identified through the addition of roughness penalties to penalise the complicated functions. The latter contributes in identifying the connection between the frequentist and the Bayesian approaches
On Hyperstructure and Musical Structure
No full textIn this paper we report on an ongoing investigation into the relationship between musical structure and hyperstructure, based on a series of open hypermedia systems research projects that have featured case studies involving musical content. We provide a general overview of the intersection between hypermedia and musical structure, drawing also on ideas from narrative structure. Through the example systems we consider techniques for building hyperstructure from musical structure and, conversely, building musical structure from hyperstructure. Additionally we describe an experiment in the sonification of hyperstructure
Semantic annotation of ubiquitous learning environments
No full textSkills-based learning environments are used to promote the acquisition of practical skills as well as decision making, communication, and problem solving. It is important to provide feedback to the students from these sessions and observations of their actions may inform the assessment process and help researchers to better understand the learning process. Through a series of prototype demonstrators, we have investigated the use of semantic annotation in the recording and subsequent understanding of such simulation environments. Our Semantic Web approach is outlined and conclusions drawn as to the suitability of different annotation methods and their combination with ubiquitous computing techniques to provide novel mechanisms for both student feedback and increased understanding of the learning environment
DEEP: a provenance-aware executable document system
No full textThe concept of executable documents is attracting growing interest from both academics and publishers since it is a promising technology for the dissemination of scientific results. Provenance is a kind of metadata that provides a rich description of the derivation history of data products starting from their original sources. It has been used in many different e-Science domains and has shown great potential in enabling reproducibility of scientific results. However, while both executable documents and provenance are aimed at enhancing the dissemination of scientific results, little has been done to explore the integration of both techniques. In this paper, we introduce the design and development of DEEP, an executable document environment that generates scientific results dynamically and interactively, and also records the provenance for these results in the document. In this system, provenance is exposed to users via an interface that provides them with an alternative way of navigating the executable document. In addition, we make use of the provenance to offer a document rollback facility to users and help to manage the system's dynamic resources
The Collaborative Semantic Grid
No full textGrid and Semantic Web technologies both enable heterogeneous resources to be joined up to achieve new functionality and capability, and their combined effectiveness has been demonstrated through a number of ‘Semantic Grid’ projects. These typically apply Semantic Web technologies in Grid applications, in a datagrid or within the Grid middleware. In this paper we suggest how both approaches also support distributed collaborative endeavours, and explore their combined role. We illustrate this ‘Collaborative Semantic Grid’ through a number of case studies, and contemplate the changing nature of collaboration as these technologies evolve
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