Athanasios Manitsaris

A conceptual framework for metadata quality assessment

Metadata quality of digital resources in a repository is an issue directly associated with the repositorys efficiency and value. In this paper, the subject of metadata quality is approached by introducing a new conceptual framework that defines it in terms of its fundamental components. Additionally, a method for assessing these components by exploiting structural and semantic relations among the resources is presented. These relations can be used to generate implied logic rules, which include, impose or prohibit certain values in the fields of a metadata record. The use of such rules can serve as a tool for conducting quality control in the records, in order to diagnose deficiencies and errors.

Semantically enhanced browsing for blind people in the WWW

The WWW is today the biggest source of information and an essential tool for many activities of daily life. Unfortunately, information seeking in this complex hypermedia environment is generally not an easy task. The potentially complex task of information seeking in the WWW is further complicated when the end-user is blind or visually impaired (VI). Usually, web pages are created without taken accessibility into account and without using HTML markup correctly to express the functional structure of documents. Both facts pose a lot of problems to VI during information seeking in the web. In this paper we discuss problems related to this issue and how the information seeking process in the WWW could become more effective and efficient for the VI. We also present an ongoing research effort, inspired from the idea of Semantic Web, aiming to enhance browsing efficiency as a result of rationalizing the way VI browse the WWW.

Browsing shortcuts as a means to improve information seeking of blind people in the WWW

This paper presents a “Semantic Web application framework” which allows different applications to be designed and developed for improving the accessibility of the World Wide Web (WWW). The framework promotes the idea of creating a community of people federating into groups (ontology creators, annotators, user-agent developers, end-users) each playing a specific role, without the coordination of any central authority. The use of a specialised voice web browser for blind people, called SeEBrowser, is presented and discussed as an example of an accessibility tool developed based on the framework. SeEBrowser utilises annotations of web pages and provides browsing shortcuts. Browsing shortcuts are mechanisms, which facilitate blind people in moving efficiently through various elements of a web page (e.g. functional elements such as forms, navigational aids etc.) during the information-seeking process, hence operating effectively as a vital counterbalance to low accessibility. Finally, an experimental user study is presented and discussed which evaluates SeEBrowser with and without the use of browsing shortcuts.

Quantifying and measuring metadata completeness

Completeness of metadata is one of the most essential characteristics of their quality. An incomplete metadata record is a record of degraded quality. Existing approaches to measure metadata completeness limit their scope in counting the existence of values in fields, regardless of the metadata hierarchy as defined in international standards. Such a traditional approach overlooks several issues that need to be taken into account. This paper presents a fine-grained metrics system for measuring metadata completeness, based on field completeness. A metadata field is considered to be a container of multiple pieces of information. In this regard, the proposed system is capable of following the hierarchy of metadata as it is set by the metadata schema and admeasuring the effect of multiple values of multivalued fields. An application of the proposed metrics system, after being configured according to specific user requirements, to measure completeness of a real-world set of metadata is demonstrated. The results prove its ability to assess the sufficiency of metadata to describe a resource and provide targeted measures of completeness throughout the metadata hierarchy.

Automatic metadata generation by utilising pre-existing metadata of related resources

Manual indexing of digital resources according to metadata standards is a laborious task. Methods and methodologies for automatically producing several parts of a resources metadata provide valuable assistance to indexers and cataloguers by reducing the burden of their manual work. A methodology, which aims at identifying inference rules for the automatic generation of a resources metadata, based on pre-existing metadata of its related resources, is introduced in this paper. Furthermore, the application of the methodology to the IEEE LOM standard and an experimental example on a working database of metadata, with a tool developed for this purpose, are demonstrated.

Analysis of navigation behaviour of blind users using Browsing Shortcuts

The World Wide Web is today the largest information seeking environment. Millions of people use it to satisfy their information needs. Although it is quite easy for able-bodied users to use it, there are still a lot of problems for people with disabilities. A major group of them are blind users. Blind users navigate the web in a different and less effective and efficient way especially when it comes to information seeking tasks. To ease the problem we introduced the Browsing Shortcuts (BSs) mechanism to enable blind people to move efficiently to various elements of a web page (e.g. functional elements such as forms, navigational aids, etc.), hence operating effectively as an interaction method and a vital counterbalance to low navigability of web pages. Although there are proofs that navigation performance was improved using the BSs mechanism, this effect had never been examined and explained in detail. In this paper, we re-analyse data collected from past experiments and review BSs usage from a navigation behaviour perspective. This is achieved by a new analysis using a visualisation method of “travel graphs” for studying the navigation methods of blind users. We compare behaviours of blind users using the BSs feature to the ones used without it to determine changes in behaviour. The basic aim behind this analysis is to examine how BSs have affected the navigation behaviour of blind users. We wished to determine how non-visual navigation using BSs assists users in parsing a web page into functional or semantic regions. Additionally, we wished to examine if and how these regions are accessed during an information seeking episode with and without the BSs mechanism. Finally, we wished to examine whether these changes are towards more rationalised information seeking behaviour. In overall, this new analysis of the recorded results indicate that the navigation model using BSs signifies more rationalised navigation and significantly change information seeking behaviour improving both navigability and information seeking performance.

LEMP: Lightweight Efficient Multicast Protocol for video on demand

In this paper, we propose a new scalable application-layer protocol, specifically designed for data streaming applications with large client sets. This is based upon a control hierarchy of successive levels for the clients, has minimal overhead with constant number of messages per client, and is robust to client and network failures, making it suitable for wireless environments. The video server bandwidth utilization is also significantly reduced. We present an analysis and simulation results, showing that LEMP is near optimum in terms of performance.

A Fine-Grained Metric System for the Completeness of Metadata

Metadata quality is an issue that can be approached from different aspects. Among the most essential properties characterizing a quality metadata record is its sufficiency to describe a resource, which is expressed as the completeness of the record. The paper presents a fine-grained metric system for measuring metadata completeness that is capable of following the hierarchy of metadata as it is set by the metadata schema and admeasuring the effect of multiple values of multi-valued fields. Moreover, it introduces the aspect of the representation level of semantically equivalent information that should be taken into account when measuring completeness. The proposed metric system, based on the definition of completeness of a field, treats several deficiencies of the traditional coarse metrics and offers the ability of targeted measures of completeness throughout the metadata hierarchy.

A Multimodal Approach for the Safeguarding and Transmission of Intangible Cultural Heritage: The Case of i-Treasures

Intangible Cultural Heritage (ICH) creations include, amongst other, music, dance, singing, theatre, human skills, and craftsmanship. These cultural expressions are usually transmitted orally and/or using gestures and are modified over a period of time, through a process of collective recreation. As the world becomes more interconnected and many different cultures come into contact, local communities run the risk of losing important elements of their ICH, while young people find it difficult to maintain the connection with the cultural heritage treasured by their elders. In this paper, we present a novel holistic approach for the safeguarding and transmission of ICH that goes beyond the mere digitization of ICH content. Based on multisensory technology for the capturing of ICH, the proposed approach enables the generation of completely novel cultural content. High-level semantics are extracted from the acquired data, enabling researchers to identify possible implicit or hidden correlations between different ICH expressions or interpretation styles and study the evolution of a specific ICH. These data, coupled with other cultural resources, are accessible through the i-Treasures Web-platform, which provides the means for supporting knowledge exchange between researchers as well as know-how transmission from ICH bearers to apprentices.

X-EDCA: A cross-layer MAC-centric mechanism for efficient multimedia transmission in congested IEEE 802.11e infrastructure networks

IEEE 802.11e is the indisputable standard for supporting multimedia traffic in modern Wireless Local Area Networks. However, it has been proven incapable of handling efficiently multimedia flows in congested networks. The main reason for this suboptimal behavior roots from the static nature of resource allocation specified in IEEE 802.11e. Dynamic tuning of the MAC parameters has demonstrated a beneficial performance in terms of application efficiency. Nevertheless, it is of great importance that this adaptation takes place by considering the multimedia traffic characteristics. In this paper, a cross-layer MAC-centric mechanism is introduced, under the name X-EDCA. The mechanism is designed to cope with high load situations in IEEE 802.11e wireless infrastructure networks by selectively prioritizing and protecting sensitive multimedia frames. The proposed scheme is evaluated and its effectiveness is proven by means of simulation.