1,721,514 research outputs found
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
Evaluation of Feasibility and Impact of Attacks against the 6top Protocol in 6TiSCH Networks
Full text linkThe 6TiSCH architecture has been gaining attraction as a promising solution to ensure reliability and security for communication in applications for the Industrial Internet of Things (IIoT). While many different aspects of the architecture have been investigated in literature, an in-depth analysis of the security features included in its design is still missing. In this paper, we assess the security vulnerabilities of the 6top protocol, a core component of the 6TiSCH architecture for enabling network nodes to negotiate communication resources. Our analysis highlights two possible attacks against the 6top protocol that can impair network performance and reliability in a significant manner. To prove the feasibility of the attacks in practice, we implemented both of them on the Contiki-NG Operating System and tested their effectiveness on a simple deployment with three Zolertia RE-Mote sensor nodes. Also, we carried out a set of simulations using Cooja in order to assess their impact on larger networks. Our results show that both attacks reduce reliability in the overall network and increase energy consumption of the network nodes
Discriminating Quantum States in the Presence of a Deutschian CTC: A Simulation Analysis
No full textIn an article published in 2009, Brun et al. proved that in the presence of a 'Deutschian' closed timelike curve, one can map K distinct nonorthogonal states (hereafter, input set) to the standard orthonormal basis of a K-dimensional state space. To implement this result, the authors proposed a quantum circuit that includes, among SWAP gates, a fixed set of controlled operators (boxes) and an algorithm for determining the unitary transformations carried out by such boxes. To our knowledge, what is still missing to complete the picture is an analysis evaluating the performance of the aforementioned circuit from an engineering perspective. The objective of this article is, therefore, to address this gap through an in-depth simulation analysis, which exploits the approach proposed by Brun et al. in 2017. This approach relies on multiple copies of an input state, multiple iterations of the circuit until a fixed point is (almost) reached. The performance analysis led us to a number of findings. First, the number of iterations is significantly high even if the number of states to be discriminated against is small, such as 2 or 3. Second, we envision that such a number may be shortened as there is plenty of room to improve the unitary transformation acting in the aforementioned controlled boxes. Third, we also revealed a relationship between the number of iterations required to get close to the fixed point and the Chernoff limit of the input set used: the higher the Chernoff bound, the smaller the number of iterations. A comparison, although partial, with another quantum circuit discriminating the nonorthogonal states, proposed by Nareddula et al. in 2018, is carried out and differences are highlighted
QBROKAGE: A Genetic Approach for QoS Cloud Brokering
No full textThe broad diffusion of Cloud Computing has fostered the proliferation of a large number of cloud computing providers. The need of Cloud Brokers arises for helping consumers in discovering, considering and comparing services with different capabilities and offered by different providers. Also, consuming services exposed by different providers, when possible, may alleviate the vendor lock-in. While it can be straightforward to choose the best provider when deploying small and homogeneous applications, things get harder if the size and complexity of applications grow up. In this paper we propose a genetic approach for Cloud Brokering, focusing on finding Infrastructure-as-a-Service (IaaS) resources for satisfying Quality of Service (QoS) requirements of applications. We performed a set of experiments with an implementation of such broker. Results show that our broker can find near-optimal solutions even when dealing with hundreds of providers, trying at the same time to mitigate the vendor lock-in
A Configurable Protocol for Quantum Entanglement Distribution to End Nodes
No full textThe primary task of a quantum repeater network is to deliver entanglement among end nodes. Most of existing entanglement distribution protocols do not consider purification, which is thus delegated to an upper layer. This is a major drawback since, once an end-to-end entangled connection (or a portion thereof) is established it cannot be purified if its fidelity (F) does not fall within an interval bounded by Fmin (greater than 0.5) and Fmax (less than 1). In this paper, we propose the Ranked Entanglement Distribution Protocol (REDiP), a connection-oriented protocol that overcomes the above drawback. This result was achieved by including in our protocol two mechanisms for carrying out jointly purification and entanglement swapping. We use simulations to investigate the impact of these mechanisms on the performance of a repeater network, in terms of throughput and fidelity. Moreover, we show how REDiP can easily be configured to implement custom entanglement swapping and purification strategies, including (but not restricted to) those adopted in two recent works
DeSQribe: Design and Synthesize Quantum Network Interoperable Protocols for Entanglement Distribution
No full textThe Quantum Internet architecture and its associated functionality are far from being standardized. Furthermore, the protocol stack that implements the abovementioned functionality is still under development. In this work, we present a framework to DEsign and Synthesize Quantum netwoRk InteroperaBle protocols for Entanglement distribution (DeSQribe), a novel iteration of the Software-Defined Networking (SDN) paradigm. DeSQribe introduces a methodology to define and implement arbitrary entanglement distribution and distillation protocols. Distinct from adaptations of existing SDN solutions to quantum networks, DeSQribe tackles quantum-specific challenges, such as the dual nature of a data plane that accommodates classical messages and quantum states. DeSQribe defines a protocol as an ordered sequence of processing units that manipulate quantum states and exchange classical messages. This high modularity encourages software reusability. A centralized controller leverages DeSQribe and dynamically orchestrates protocols on network devices. Finally, DeSQribe's technology-agnostic nature assures seamless integration across diverse quantum technologies. We showcase how to implement and combine entanglement distribution protocols of very different natures (e.g., connectionless, connection-oriented) with DeSQribe, proving its flexibility and timeliness
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