Abstract
Digitized radio-over-fiber (D-RoF) transport schemes are being pointed as viable alternative solutions to their analog counterparts, in order to avoid distortion/dynamic range problems. Here we propose a novel D-RoF architecture that takes advantage of a bandpass sigma-delta modulator at the transmitter which subsequently permits the usage of a simpler/cheaper base station that avoids the employment of a digital to analog converter. The proposed architecture exploits the properties of the digital signal to enable the extraction of an higher carrier frequency through the employment of a bandpass filter. Furthermore, we present a comprehensive analysis regarding the impact of a low-cost electro-optic modulation on the quality of received demodulated signal. Finally, a comparison performance analysis between the conventional D-RoF and the proposed architecture is presented. We conclude that although the proposed architecture performs similarly to conventional D-RoF schemes, it is more competitive for either upgrading installed systems as well as for new deployments. (C) 2014 Optical Society of America

Abstract
Purpose - This study investigates the use of the internet by the largest companies based in Sweden and Spain to communicate their engagement in corporate social responsibility (CSR) activities. Its purpose is to analyse to what extent, if any, are there differences in the CSR communication on the web sites companies from these two countries. Design/methodology/approach - The paper examines CSR communication on the internet by companies based in Sweden and Spain. Non-parametric statistics are used to analyse some factors that influence disclosure, namely country, industry affiliation, profitability, and size. Findings - Findings suggest that in spite of the existence of a high degree of similarity between CSR communication practices, companies from Spain place social responsibility information in more prominent sections and devote more space to said information. Swedish companies are found to disclose more their codes of conduct/ethics and CSR-related press clips and published articles. Research limitations/implications - The sample is small. There may be content analysis issues associated with subjectivity in the coding process. Originality/value - It adds to the scarce research on CSR communication by companies in these countries by providing new empirical data and extends prior research comparing such practices in different international models of CSR.

Abstract
Computer-supported online 3-D virtual world environments have been waxed and waned in interest and representativeness for supporting collaborative- and simulation-based practices. In a post-modern societal framework that requires inexpensive solutions for high-risk situations, research efforts in virtual worlds have developed a basis for understanding the use of virtual reality for multidisciplinary scenarios such as distance learning, training, therapy treatments, and social interaction. Complex relationships can be established simultaneously between several students functioning as integrated learning units using different media, and interacting with their physical environment in the context of real-world settings. In this sense, a recurrently updated research agenda for virtual worlds can characterize the current needs at a systematic way. This paper presents a meta-analysis of 35 publications to identify gaps and opportunities for research in collaborative three-dimensional environments based on content analysis. At a general perspective, there is a lack of established approaches to measure the influence and research potential of sociocultural factors in virtual worlds’ usage, autism spectrum and other healthcare-related settings, learning outcomes, content characteristics, task support for groups and crowds, and online data collection.

Abstract
There is an increasing concern about transient errors in deep sub-micron processor architectures. Software-only error detection approaches that exploit program invariants for silent error detection incur large execution overheads and are unreliable as state can be corrupted after invariant check points. In this paper we explore the use of configurable hardware structures for the continuous evaluation of high-level program invariants at the assembly-level. We evaluate the resource requirements and performance of the proposed hardware structures on a contemporary reconfigurable hardware device. The results, for a small set of kernels codes, reveal that these hardware structures require a very small number of resources and are fairly insensitive to the complexity of the invariants thus making the proposed hardware approach an attractive alternative to software-only invariant checking by integrating them in traditional processor architectures. © 2014 Springer International Publishing Switzerland.

Abstract

Abstract
This work focuses on the development of a pressure-loop controller for a hybrid brake-by-wire system, composed of a hydraulic link and an electro-mechanical actuator. Towards this goal, we will start by constructing a reduced model that is capable of capturing the fundamental dynamics of the actuator, which is particularly useful for control design purposes. Motivated by the large friction disturbances that affect the system, we also investigate linear-in-the-parameter models suitable for (online) model-based friction compensation. More specifically, results from the theory of function approximation, together with optimization techniques, are explored to approximate the Stribeck friction model through a linear-in-the-parameter model. This new linear-in-the-parameter model is then employed in the design of a control law for tracking the braking pressure of the hybrid brake-by-wire. The main features of this controller are the robustness to parametric uncertainties, thanks to the inclusion of a switching-sigma adaptive mechanism, and the attenuation of non-parametric disturbances with a continuous sliding mode action. The stability and robustness properties of the closed-loop system are investigated with the help of the Lyapunov method. Finally, experimental tests demonstrate the effectiveness of the proposed approach and its ability to handle disturbances.