1,721,057 research outputs found
Adaptive, dynamic, and resilient systems
No full textAs the complexity of today’s networked computer systems grows, they become increasingly difficult to understand, predict, and control. Addressing these challenges requires new approaches to building these systems. Adaptive, Dynamic, and Resilient Systems supplies readers with various perspectives of the critical infrastructure that systems of networked computers rely on. It introduces the key issues, describes their interrelationships, and presents new research in support of these areas. The book presents the insights of a different group of international experts in each chapter. Reporting on recent developments in adaptive systems, it begins with a survey of application fields. It explains the requirements of such fields in terms of adaptation and resilience. It also provides some abstract relationship graphs that illustrate the key attributes of distributed systems to supply you with a better understanding of these factors and their dependencies. The text examines resilient adaptive systems from the perspectives of mobile, infrastructure, and enterprise systems and protecting critical infrastructure. It details various approaches for building adaptive, dynamic, and resilient systems-including agile, grid, and autonomic computing; multi-agent-based and biologically inspired approaches; and self-organizing systems. The book includes many stories of successful applications that illustrate a diversified range of cutting-edge approaches. It concludes by covering related topics and techniques that can help to boost adaptation and resilience in your systems
Introduction
No full textA True Story Los Angeles, California, December 10, 2012, 9:00 AM. John has just arrived at his office and is trying to access his email but experiences many problems. The performance is slow, timeouts expire, and he receives a number of “Server Error 502" messages. He is wondering whether the problem is with his client, with the network connection, or with the server. He cannot know that thousands of other users are experiencing similar problems-not only with emails but also with other services from the same provider
Mockets: A Novel Message-Oriented Communications Middleware for the Wireless Internet
No full textWireless networking is becoming increasingly important for ubiquitous access to the Internet and the Web. However, wireless networks exhibit significant reliability and performance problems, with frequent disconnections, congestions, and packet losses. For these reasons, the traditional TCP/IP suite, designed for
wired networks, offers poor performance and inadequate communication semantics in this scenario. There are several research efforts in both protocols and communication infrastructures aimed at producing solutions better suited to wireless network characteristics. This paper presents Mockets, a novel communications middleware specifically designed for wireless networking scenarios. The Mockets middleware permits a communication endpoint to be moved from one node to another without interrupting the communication session. In addition, Mockets provides several delivery services with different
communication semantics, semantic classification of data, cancellation/replacement of enqueued data, and priority/lifetime assignment to messages. Initial experimental results in a wireless network scenario show
that the Mockets middleware achieves better performance levels than traditional TCP-based infrastructure
Reinforcement Learning for value-based Placement of Fog Services
No full textOptimal service and resource management in Fog Computing is an active research area in academia. In fact, to fulfill the promise to enable a new generation of immersive, adaptive, and context-aware services, Fog Computing requires novel solutions capable of better exploiting the available computational and network resources at the edge. Resource management in Fog Computing could particularly benefit from self- * approaches capable of learning the best resource allocation strategies to adapt to the ever changing conditions. In this context, Reinforcement Learning (RL), a technique that allows to train software agents to learn which actions maximize a reward, represents a compelling solution to investigate. In this paper, we explore RL as an optimization method for the value-based management of Fog services over a pool of Fog nodes. More specifically, we propose FogReinForce, a solution based on Deep Q-Network (DQN) algorithm that learns to select the allocation for service components that maximizes the value-based utility provided by those services
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Quantitative Aspects in Security Assurance, Special Issue of the International Journal of Secure Software Engineering (IJSSE)
No full textBursaphelenchus suri n. sp. : a second Bursaphelenchus syconial parasite of figs supports adaptive radiation among section Sycomorus figs
Full text linkSUPPORTING INFORMATION : S1 Text. Typological description of Bursaphelenchus suri n. sp. in traditional telegraphic style.The nematode genus Bursaphelenchus is a highly divergent group. This genus mainly consists of mycophagous entomophilic species, but some species have specialized as obligate
or facultative plant parasites, facultative insect parasites, or exhibit feeding dimorphism
(phenotypic plasticity) leading to mycophagous and predatory forms. In the present study, a
new Bursaphelenchus species, B. suri n. sp. was isolated from fresh syconia (figs) of Ficus
sur and is described and illustrated based on its typological characters and molecular phylogenetic status. The new species is characterized by its highly derived feeding structures
found in obligate plant parasites, lip possessing a labial disc and a long and thick stylet with
a long conus and extremely well-developed basal swellings. In addition, slender body of
both sexes is characteristic of the species. The new species is phylogenetically and typologically closely related to B. sycophilus, i.e., these two species share the characteristic feeding
structures and form a well-supported clade within the B. fungivorus group in the genus. Biologically, these two species are both isolated from fresh figs of the section Sycomorus. However, the new species differs from B. sycophilus by the length of the female post-uterine sac
and the shape of the male spicule, i.e., the new species has a long post-uterine sac and
spicule condylus without dorsal recurvature. Thus, the new species is the second obligate
fig parasite of the genus, and the evolutionary relationship between the B. suri n. sp. and B.
sycophilus clade and section Sycomorus figs is hypothesized as an example of adaptive
radiation with more species to be discovered.The National Research Foundation of South Africa and Grant-in-Aid for Scientific Research (B) from the Japan Society for the Promotion of Science.http://www.plosone.orgdm2022BiochemistryGeneticsMicrobiology and Plant Patholog
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