Catálogo de publicaciones - revistas

<jats:p>Many security and software testing applications require checking whether certain properties of a program hold for any possible usage scenario. For instance, a tool for identifying software vulnerabilities may need to rule out the existence of any backdoor to bypass a program’s authentication. One approach would be to test the program using different, possibly random inputs. As the backdoor may only be hit for very specific program workloads, automated exploration of the space of possible inputs is of the essence. Symbolic execution provides an elegant solution to the problem, by systematically exploring many possible execution paths at the same time without necessarily requiring concrete inputs. Rather than taking on fully specified input values, the technique abstractly represents them as symbols, resorting to constraint solvers to construct actual instances that would cause property violations. Symbolic execution has been incubated in dozens of tools developed over the past four decades, leading to major practical breakthroughs in a number of prominent software reliability applications. The goal of this survey is to provide an overview of the main ideas, challenges, and solutions developed in the area, distilling them for a broad audience.</jats:p>

<jats:p> In the past decade, positioning system-enabled devices such as smartphones have become most prevalent. This functionality brings the increasing popularity of <jats:italic>location-based services</jats:italic> in business as well as daily applications such as navigation, targeted advertising, and location-based social networking. <jats:italic>Continuous spatial queries</jats:italic> serve as a building block for location-based services. As an example, an Uber driver may want to be kept aware of the nearest customers or service stations. Continuous spatial queries require updates to the query result as the query or data objects are moving. This poses challenges to the query efficiency, which is crucial to the user experience of a service. A large number of approaches address this efficiency issue using the concept of <jats:italic>safe region</jats:italic> . A safe region is a region within which arbitrary movement of an object leaves the query result unchanged. Such a region helps reduce the frequency of query result update and hence improves query efficiency. As a result, safe region-based approaches have been popular for processing various types of continuous spatial queries. Safe regions have interesting theoretical properties and are worth in-depth analysis. We provide a comparative study of safe region-based approaches. We describe how safe regions are computed for different types of continuous spatial queries, showing how they improve query efficiency. We compare the different safe region-based approaches and discuss possible further improvements. </jats:p>

<jats:p>In the past decade, Convolutional Neural Networks (CNNs) have demonstrated state-of-the-art performance in various Artificial Intelligence tasks. To accelerate the experimentation and development of CNNs, several software frameworks have been released, primarily targeting power-hungry CPUs and GPUs. In this context, reconfigurable hardware in the form of FPGAs constitutes a potential alternative platform that can be integrated in the existing deep-learning ecosystem to provide a tunable balance between performance, power consumption, and programmability. In this article, a survey of the existing CNN-to-FPGA toolflows is presented, comprising a comparative study of their key characteristics, which include the supported applications, architectural choices, design space exploration methods, and achieved performance. Moreover, major challenges and objectives introduced by the latest trends in CNN algorithmic research are identified and presented. Finally, a uniform evaluation methodology is proposed, aiming at the comprehensive, complete, and in-depth evaluation of CNN-to-FPGA toolflows.</jats:p>

<jats:p>The Internet has undergone dramatic changes in the past 2 decades and now forms a global communication platform that billions of users rely on for their daily activities. While this transformation has brought tremendous benefits to society, it has also created new threats to online privacy, such as omnipotent governmental surveillance. As a result, public interest in systems for anonymous communication has drastically increased. In this work, we survey previous research on designing, developing, and deploying systems for anonymous communication. Our taxonomy and comparative assessment provide important insights about the differences between the existing classes of anonymous communication protocols.</jats:p>

<jats:p>Autoscaling system can reconfigure cloud-based services and applications, through various configurations of cloud software and provisions of hardware resources, to adapt to the changing environment at runtime. Such a behavior offers the foundation for achieving elasticity in a modern cloud computing paradigm. Given the dynamic and uncertain nature of the shared cloud infrastructure, the cloud autoscaling system has been engineered as one of the most complex, sophisticated, and intelligent artifacts created by humans, aiming to achieve self-aware, self-adaptive, and dependable runtime scaling. Yet the existing Self-aware and Self-adaptive Cloud Autoscaling System (SSCAS) is not at a state where it can be reliably exploited in the cloud. In this article, we survey the state-of-the-art research studies on SSCAS and provide a comprehensive taxonomy for this field. We present detailed analysis of the results and provide insights on open challenges, as well as the promising directions that are worth investigated in the future work of this area of research. Our survey and taxonomy contribute to the fundamentals of engineering more intelligent autoscaling systems in the cloud.</jats:p>

<jats:p>Intrusion alert analysis is an attractive and active topic in the area of intrusion detection systems. In recent decades, many research communities have been working in this field. The main objective of this article is to achieve a taxonomy of research fields in intrusion alert analysis by using a systematic mapping study of 468 high-quality papers. The results show that there are 10 different research topics in the field, which can be classified into three broad groups: pre-processing, processing, and post-processing. The processing group contains most of the research works, and the post-processing group is newer than others.</jats:p>

<jats:p>The world is becoming a more conjunct place and the number of data sources such as social networks, online transactions, web search engines, and mobile devices is increasing even more than had been predicted. A large percentage of this growing dataset exists in the form of linked data, more generally, graphs, and of unprecedented sizes. While today's data from social networks contain hundreds of millions of nodes connected by billions of edges, inter-connected data from globally distributed sensors that forms the Internet of Things can cause this to grow exponentially larger. Although analyzing these large graphs is critical for the companies and governments that own them, big data tools designed for text and tuple analysis such as MapReduce cannot process them efficiently. So, graph distributed processing abstractions and systems are developed to design iterative graph algorithms and process large graphs with better performance and scalability. These graph frameworks propose novel methods or extend previous methods for processing graph data. In this article, we propose a taxonomy of graph processing systems and map existing systems to this classification. This captures the diversity in programming and computation models, runtime aspects of partitioning and communication, both for in-memory and distributed frameworks. Our effort helps to highlight key distinctions in architectural approaches, and identifies gaps for future research in scalable graph systems.</jats:p>

<jats:p>Vehicular ad hoc networks (VANETs) are essential components of the intelligent transport systems. They are attracting an increasing amount of interest in research and industrial sectors. Vehicular nodes are capable of transporting, sensing, processing information, and wireless communication, which makes them more vulnerable to worm infections than conventional hosts. This survey provides an overview on worm spreading over VANETs. We first briefly introduce the computer worms. Then the V2X communication and applications are discussed from malware and worms propagation perspective to show the indispensability of studying the characteristics of worm propagating on VANETs. The recent literature on worm spreading and containment on VANETs are categorized based on their research methods. The improvements and limitations of the existing studies are discussed. Next, the main factors influencing worm spreading in vehicular networks are discussed followed by a summary of countermeasure strategies designed to deal with these worms.</jats:p>

<jats:p>Thermal modeling and simulation have become imperative in recent years owing to the increased power density of high performance microprocessors. Temperature is a first-order design criteria, and hence special consideration has to be given to it in every stage of the design process. If not properly accounted for, temperature can have disastrous effects on the performance of the chip, often leading to failure. To streamline research efforts, there is a strong need for a comprehensive survey of the techniques and tools available for thermal simulation. This will help new researchers entering the field to quickly familiarize themselves with the state of the art and enable existing researchers to further improve upon their proposed techniques. In this article, we present a survey of the package level thermal simulation techniques developed over the past two decades.</jats:p>

<jats:p>Anomaly detection has numerous applications in diverse fields. For example, it has been widely used for discovering network intrusions and malicious events. It has also been used in numerous other applications such as identifying medical malpractice or credit fraud. Detection of anomalies in quantitative data has received a considerable attention in the literature and has a venerable history. By contrast, and despite the widespread availability use of categorical data in practice, anomaly detection in categorical data has received relatively little attention as compared to quantitative data. This is because detection of anomalies in categorical data is a challenging problem. Some anomaly detection techniques depend on identifying a representative pattern then measuring distances between objects and this pattern. Objects that are far from this pattern are declared as anomalies. However, identifying patterns and measuring distances are not easy in categorical data compared with quantitative data. Fortunately, several papers focussing on the detection of anomalies in categorical data have been published in the recent literature. In this article, we provide a comprehensive review of the research on the anomaly detection problem in categorical data. Previous review articles focus on either the statistics literature or the machine learning and computer science literature. This review article combines both literatures. We review 36 methods for the detection of anomalies in categorical data in both literatures and classify them into 12 different categories based on the conceptual definition of anomalies they use. For each approach, we survey anomaly detection methods, and then show the similarities and differences among them. We emphasize two important issues, the number of parameters each method requires and its time complexity. The first issue is critical, because the performance of these methods are sensitive to the choice of these parameters. The time complexity is also very important in real applications especially in big data applications. We report the time complexity if it is reported by the authors of the methods. If it is not, then we derive it ourselves and report it in this article. In addition, we discuss the common problems and the future directions of the anomaly detection in categorical data.</jats:p>