An algebra and conceptual model for semantic tagging of collaborative digital libraries

Cost-effective semantic description and annotation of shared knowledge resources has always been of great importance for digital libraries and large scale information systems in general. With the emergence of the Social Web and Web 2.0 technologies, a more effective semantic description and annotation, e.g., folksonomies, of digital library contents is envisioned to take place in collaborative and personalised environments. However, there is a lack of foundation and mathematical rigour for coping with contextualised management and retrieval of semantic annotations throughout their evolution as well as diversity in users and user communities. In this paper, we propose an ontological foundation for semantic annotations of digital libraries in terms of flexonomies. The proposed theoretical model relies on a high dimensional space with algebraic operators for contextualised access of semantic tags and annotations. The set of the proposed algebraic operators, however, is an adaptation of the set theoretic operators selection, projection, difference, intersection, union in database theory. To this extent, the proposed model is meant to lay the ontological foundation for a Digital Library 2.0 project in terms of geometric spaces rather than logic (description) based formalisms as a more efficient and scalable solution to the semantic annotation problem in large scale.

A comparative study on the modified Max-Log-MAP turbodecoding by extrinsic information scaling

A simple but effective technique to improve the performance of the Max-Log-MAP algorithm is to scale the extrinsic information exchanged between two MAP decoders. A comprehensive analysis of the selection of the scaling factors according to channel conditions and decoding iterations is presented in this paper. Choosing a constant scaling factor for all SNRs and iterations is compared with the best scaling factor selection for changing channel conditions and decoding iterations. It is observed that a constant scaling factor for all channel conditions and decoding iterations is the best solution and provides a 0.2-0.4 dB gain over the standard Max- Log-MAP algorithm. Therefore, a constant scaling factor should be chosen for the best compromise.

The modified Max-Log-MAP turbo decoding algorithm by extrinsic information scaling for wireless applications

The iterative nature of turbo-decoding algorithms increases their complexity compare to conventional FEC decoding algorithms. Two iterative decoding algorithms, Soft-Output-Viterbi Algorithm (SOVA) and Maximum A posteriori Probability (MAP) Algorithm require complex decoding operations over several iteration cycles. So, for real-time implementation of turbo codes, reducing the decoder complexity while preserving bit-error-rate (BER) performance is an important design consideration. In this chapter, a modification to the Max-Log-MAP algorithm is presented. This modification is to scale the extrinsic information exchange between the constituent decoders. The remainder of this chapter is organized as follows: An overview of the turbo encoding and decoding processes, the MAP algorithm and its simplified versions the Log-MAP and Max-Log-MAP algorithms are presented in section 1. The extrinsic information scaling is introduced, simulation results are presented, and the performance of different methods to choose the best scaling factor is discussed in Section 2. Section 3 discusses trends and applications of turbo coding from the perspective of wireless applications.

Accessibility instruments for planning practice: A review of European experiences

Although a large body of literature has been produced on the theoretical definitions and measurements of accessibility, the extent to which such indicators are used in planning practice is less clear. This research explores the gap between theory and application by seeking to understand what the new wave of accessibility instruments (AIs) prepared for spatial and transport planning practice purports to offer the users of AIs. Starting from the question of how urban and transport planners are designing AIs, the article analyzes and describes the AIs developed over the last decade (mainly in Europe), offering a structured overview and a clear categorization of how accessibility measures can be applied. The paper identifies AI characteristics, and considers their usability, based on AI developer perceptions.

Accessibility Planning tools for sustainable and integrated Land Use/Transport (LUT) development: an application to Rome

The paper fits into the themes of sustainable accessibility planning in urban areas, that can be defined as the integration of transport and land use planning to achieve sustainable development. In particular the study proposes a tool to support the choices of activities location, which is based on a new aggregate (zone-specific) indicator: the ‘Marginal Activity Access Cost’, providing estimation in monetary terms of the impacts on mobility and on the environment of locating one new activity in a specific zone of the urban area. The proposed indicator is validated through an application to the urban area of Rome.

An accessibility planning tool for network transit oriented development : SNAP

In the academic debate regarding the influences between urban form, built environment and travel patterns, a specific idea that has taken hold is that more compact urban development around railway stations, often referred to as Transit Oriented Development (TOD), contributes to the control of vehicle travel and to more sustainable metropolitan systems. According to this general principle this work proposes a GIS accessibility tool for the design of polycentric transit oriented scenario: SNAP - Station Network Accessibility Planning tool. In the first part the state of the art on Transit Oriented Development policies in Europe is presented with a focus on three study cases. In the second part the SNAP tool is described, with remarks to the approach, the methodology and the used indicators. Furthermore the paper discusses an application to the metropolitan area of Naples.

Accessibility Instrument Survey

This chapter presents the main results of the Accessibility Instrument Survey (AIS), collecting basic information on each of the accessibility instruments reviewed in this report (for more detail on these Instruments see Chapter 3). The aim of the survey was to enable quick, objective and comparable overviews of each of the reviewed accessibility instruments. The information collected will enable the categorization of accessibility instruments present in this research, aiming to be a reference for future categorization of accessibility instruments for planning practice. These categories will support the analysis of the coverage of accessibility instruments in this research, i.e., identify how representative this research is across different accessibility instrument types. In addition, these will be used to analyse the characteristics and concerns which most frequently underlie the development of accessibility instruments. Finally, the survey also collects developer’s perceptions on the usefulness of their accessibility instruments in planning practice, enabling the first insight into the main research question of this COST Action, although limited to the developer’s point of view. In summary, the results of the survey will be used for four purposes: Development of an accessibility instrument sheet for each accessibility instrument summarizing its main characteristics (Appendix A); Identify the coverage of accessibility instrument types present in this research (Section 4.3.1) discussing the representativeness of this Action; Provide a glimpse on the characteristics and concerns which most frequently underlie the development of accessibility instruments (Section 4.3.2); Provide a first insight into the perceived usefulness of accessibility instruments in planning practice from the point of view of the developer (Section 4.3.2 and Section 4.3.3). The next section provides an overview of the Survey describing the information collected. This section also describes the development process of this survey including data collection, dates and means. The results of the survey are analysed in the third section starting with a discussion on the coverage of accessibility instruments reviewed by this research (Section 4.3.1), identifying accessibility measure types which are represented and which are absent. This discussion is accompanied by the presentation of the main categories of accessibility instruments from the perspective of the end user. These categories try to summarize the main concerns planning practitioners are expected to have when searching for an accessibility instrument and is built upon some of the information collected by the survey. Following, the third section also presents a general analysis of the results (Section 4.3.2), focussing on the dominant characteristics of the accessibility instruments reviewed and on the developer’s perception of the usefulness their instrument will have for end users. The section ends with a brief cross analysis of results (Section 4.3.3) trying to identify relationships between accessibility instrument characteristics and perceptions of usefulness by developers. The fourth and last section presents the main conclusions of this study.