Catálogo de publicaciones - revistas

<jats:p>The increasing functional and nonfunctional requirements of real-time applications, the advent of mixed criticality computing, and the necessity of reducing costs are leading to an increase in the interest for employing COTS hardware in real-time domains. In this scenario, the Linux kernel is emerging as a valuable solution on the software side, thanks to the rich support for hardware devices and peripherals, along with a well-established programming environment. However, Linux has been developed as a general-purpose operating system, followed by several approaches to introduce actual real-time capabilities in the kernel. Among these, the PREEMPT_RT patch, developed by the kernel maintainers, has the goal to increase the predictability and reduce the latencies of the kernel directly modifying the existent kernel code. This article aims at providing a survey of the state-of-the-art approaches for building real-time Linux-based systems, with a focus on PREEMPT_RT, its evolution, and the challenges that should be addressed in order to move PREEMPT_RT one step ahead. Finally, we present some applications and use cases that have already benefited from the introduction of this patch.</jats:p>

<jats:p>Cross-Cloud Federation (CCF) is beneficial for heterogeneous Cloud Service Providers (CSPs) for leasing additional resources from each other. Despite the benefits of on-demand scalability and enhanced service footprints for better service quality, the adoption of CCF is however mainly hindered due to the lack of a comprehensive trust model. The basic aim of such a model should be to address the security and performance concerns of a home CSP on its foreign peers before placing its users’ data and applications in their premises. A transitivity of users’ trust on home CSP and home CSP's trust on its foreign CSPs marks the uniqueness of trust paradigm in CCF. Addressing the concerns of cloud-to-cloud trust paradigm is inevitable to achieve users’ trust in a federation. Various trust models have been proposed in literature for conventional and multi-cloud computing environments. They focus on user requirements but none on federation perspective. Their applicability to CCF for addressing the concerns of cloud-to-cloud trust paradigm requires further consideration. For this reason, we have first outlined the general characteristics of CCF as being dynamic, multi-level and heterogeneous. Afterwards, cloud-to-cloud trust paradigm is proposed based on a set of unique principles identified as (i) trust bi-directionality, (ii) trust composition, (iii) delegation control, and (iv) Resource awareness. An insightful review of Trust Management Systems (TMS) proposed in literature reveals their shortcomings in addressing the requirements of cloud-to-cloud trust paradigm. To overcome these shortcomings, we suggest that some challenges can be merely addressed by aligning the existing methods to the nature of CCF. The remaining challenges require entirely new mechanisms to be introduced. A demonstration of this concept is presented in the form of a requirement matrix suggesting how the characteristics and properties of both CCF and the TMS are influenced by each other. This requirement matrix reveals the potential avenues of research for a TMS aimed specifically for CCF.</jats:p>

<jats:p>Several mathematical frameworks have been used to model the information retrieval (IR) process, among them, formal logics. Logic-based IR models upgrade the IR process from document-query comparison to an inference process, in which both documents and queries are expressed as sentences of the selected formal logic. The underlying formal logic also permits one to represent and integrate knowledge in the IR process. One of the main obstacles that has prevented the adoption and large-scale diffusion of logic-based IR systems is their complexity. However, several logic-based IR models have been recently proposed that are applicable to large-scale data collections. In this survey, we present an overview of the most prominent logical IR models that have been proposed in the literature. The considered logical models are categorized under different axes, which include the considered logics and the way in which uncertainty has been modeled, for example, degrees of belief or degrees of truth. Accordingly, the main contribution of the article is to categorize the state-of-the-art logical models on a fine-grained basis, and for the considered models the related implementation aspects are described. Consequently, the proposed survey is finalized to better understand and compare the different logical IR models. Last, but not least, this article aims at reconsidering the potentials of logical approaches to IR by outlining the advances of logic-based approaches in close research areas.</jats:p>

<jats:p>This article takes a problem-oriented perspective and presents a comprehensive review of transfer-learning methods, both shallow and deep, for cross-dataset visual recognition. Specifically, it categorises the cross-dataset recognition into 17 problems based on a set of carefully chosen data and label attributes. Such a problem-oriented taxonomy has allowed us to examine how different transfer-learning approaches tackle each problem and how well each problem has been researched to date. The comprehensive problem-oriented review of the advances in transfer learning with respect to the problem has not only revealed the challenges in transfer learning for visual recognition but also the problems (e.g., 8 of the 17 problems) that have been scarcely studied. This survey not only presents an up-to-date technical review for researchers but also a systematic approach and a reference for a machine-learning practitioner to categorise a real problem and to look up for a possible solution accordingly.</jats:p>

<jats:p>With the growing volume of online information, recommender systems have been an effective strategy to overcome information overload. The utility of recommender systems cannot be overstated, given their widespread adoption in many web applications, along with their potential impact to ameliorate many problems related to over-choice. In recent years, deep learning has garnered considerable interest in many research fields such as computer vision and natural language processing, owing not only to stellar performance but also to the attractive property of learning feature representations from scratch. The influence of deep learning is also pervasive, recently demonstrating its effectiveness when applied to information retrieval and recommender systems research. The field of deep learning in recommender system is flourishing. This article aims to provide a comprehensive review of recent research efforts on deep learning-based recommender systems. More concretely, we provide and devise a taxonomy of deep learning-based recommendation models, along with a comprehensive summary of the state of the art. Finally, we expand on current trends and provide new perspectives pertaining to this new and exciting development of the field.</jats:p>

<jats:p>Virtualization is a key enabler of various modern computing technologies. However, it brings additional vulnerabilities that can be exploited to affect the availability, integrity, and confidentiality of the underlying resources and services. The dynamic and shared nature of the virtualization poses additional challenges to the traditional security solutions. This article explores the vulnerabilities, threats, and attacks relevant to virtualization. We analyze the existing security solutions and identify the research gaps that can help the research community to develop a secured virtualization platform for current and future computing technologies.</jats:p>

<jats:p>Urban computing is an emerging area of investigation in which researchers study cities using digital data. Location-Based Social Networks (LBSNs) generate one specific type of digital data that offers unprecedented geographic and temporal resolutions. We discuss fundamental concepts of urban computing leveraging LBSN data and present a survey of recent urban computing studies that make use of LBSN data. We also point out the opportunities and challenges that those studies open.</jats:p>

<jats:p>Generative Adversarial Networks (GANs) have received wide attention in the machine learning field for their potential to learn high-dimensional, complex real data distribution. Specifically, they do not rely on any assumptions about the distribution and can generate real-like samples from latent space in a simple manner. This powerful property allows GANs to be applied to various applications such as image synthesis, image attribute editing, image translation, domain adaptation, and other academic fields. In this article, we discuss the details of GANs for those readers who are familiar with, but do not comprehend GANs deeply or who wish to view GANs from various perspectives. In addition, we explain how GANs operates and the fundamental meaning of various objective functions that have been suggested recently. We then focus on how the GAN can be combined with an autoencoder framework. Finally, we enumerate the GAN variants that are applied to various tasks and other fields for those who are interested in exploiting GANs for their research.</jats:p>

<jats:p>The emergence of the Internet of things and the widespread deployment of diverse computing systems have led to the formation of heterogeneous multi-agent systems (MAS) to complete a variety of tasks. Motivated to highlight the state of the art on existing MAS while identifying their limitations, remaining challenges, and possible future directions, we survey recent contributions to the field. We focus on robot agents and emphasize the challenges of MAS sub-fields including task decomposition, coalition formation, task allocation, perception, and multi-agent planning and control. While some components have seen more advancements than others, more research is required before effective autonomous MAS can be deployed in real smart city settings that are less restrictive than the assumed validation environments of MAS. Specifically, more autonomous end-to-end solutions need to be experimentally tested and developed while incorporating natural language ontology and dictionaries to automate complex task decomposition and leveraging big data advancements to improve perception algorithms for robotics.</jats:p>

<jats:p>The way people walk is a strong correlate of their identity. Several studies have shown that both humans and machines can recognize individuals just by their gait, given that proper measurements of the observed motion patterns are available. For surveillance applications, gait is also attractive, because it does not require active collaboration from users and is hard to fake. However, the acquisition of good-quality measures of a person’s motion patterns in unconstrained environments, (e.g., in person re-identification applications) has proved very challenging in practice. Existing technology (video cameras) suffer from changes in viewpoint, daylight, clothing, accessories, and other variations in the person’s appearance. Novel three-dimensional sensors are bringing new promises to the field, but still many research issues are open. This article presents a survey of the work done in gait analysis for re-identification in the past decade, looking at the main approaches, datasets, and evaluation methodologies. We identify several relevant dimensions of the problem and provide a taxonomic analysis of the current state of the art. Finally, we discuss the levels of performance achievable with the current technology and give a perspective of the most challenging and promising directions of research for the future.</jats:p>