IEEE 802.11e (EDCA) analysis in the presence of hidden stations

AbstractThe key contribution of this paper is the combined analytical analysis of both saturated and non-saturated throughput of IEEE 802.11e networks in the presence of hidden stations. This approach is an extension to earlier works by other authors which provided Markov chain analysis to the IEEE 802.11 family under various assumptions. Our approach also modifies earlier expressions for the probability that a station transmits a packet in a vulnerable period. The numerical results provide the impact of the access categories on the channel throughput. Various throughput results under different mechanisms are presented

Cyber Infrastructure Protection: Vol. III

Despite leaps in technological advancements made in computing system hardware and software areas, we still hear about massive cyberattacks that result in enormous data losses. Cyberattacks in 2015 included: sophisticated attacks that targeted Ashley Madison, the U.S. Office of Personnel Management (OPM), the White House, and Anthem; and in 2014, cyberattacks were directed at Sony Pictures Entertainment, Home Depot, J.P. Morgan Chase, a German steel factory, a South Korean nuclear plant, eBay, and others. These attacks and many others highlight the continued vulnerability of various cyber infrastructures and the critical need for strong cyber infrastructure protection (CIP). This book addresses critical issues in cybersecurity. Topics discussed include: a cooperative international deterrence capability as an essential tool in cybersecurity; an estimation of the costs of cybercrime; the impact of prosecuting spammers on fraud and malware contained in email spam; cybersecurity and privacy in smart cities; smart cities demand smart security; and, a smart grid vulnerability assessment using national testbed networks.https://press.armywarcollege.edu/monographs/1412/thumbnail.jp

Analysis of RC Continuous Beams Strengthened with FRP Plates: A Finite Element Model

Strengthening of reinforced concrete (RC) beams with externally bonded fibre reinforced polymer (FRP) plates/sheets technique has become widespread in the last two decades. Although a great deal of research has been conducted on simply supported RC beams, a few studies have been carried out on continuous beams strengthened with FRP composites.  This paper presents a simple uniaxial nonlinear finite-element model (UNFEM) that is able to accurately estimate the load-carrying capacity and the behaviour of RC continuous beams flexurally strengthened with externally bonded FRP plates on both of the upper and lower fibres. A 21-degree of freedom element is proposed with layer-discretization of the cross-sections for finite element (FE) modelling. Realistic nonlinear constitutive relations are employed to describe the stress-strain behaviour of each component of the strengthened beam. The FE model is based on nonlinear fracture mechanics. The interfacial shear and normal stresses in the adhesive layer are presented using an analytical uncoupled cohesive zone model with a mixed-mode fracture criterion. The results of the proposed FE model are verified by comparison with various selected experimental measurements available in the literature. The numerical results of the plated beams (beams strengthened with FRP plates) agreed very well with the experimental results. The use of FRP increased the ultimate load capacity up to 100 % compared with the non-strengthened beams as occurred in series (S). The major objective of the current model is to help engineers’ model FRP-strengthened RC continuous beams in a simple manner

Could the ‘Spinner Innovation’ and ‘Triple Helix’ Models Improve System Innovation?

Although several prior studies have outlined and examined models associated with knowledge and innovation in different fields, the literature lacks any solid insights combining the Triple Helix model and the Spinner Innovation model and ascertaining their relevance to innovation. This article correspondingly presents an unprecedented alternative based on two innovation models, analyzing and structuring a process to innovate in different economic sectors. In doing so, this paper seeks to explore how this integration between Spinner Innovation and Triple Helix models could have a significant influence to improve system innovation. We collected data from the Scopus database spanning the period between 2012 and 2021 to study the integration of the models. The analysis identifies how these models differ but are nevertheless of complementary importance for developing regional and national economies through combining the “helices”, the “fidgets” and the framework integrating both models and their components to system innovation.info:eu-repo/semantics/publishedVersio

Strategies for Water Reclamation: The Role of Policy and Technology in the Las Vegas Water Supply

The goals of this report are to: (i) consider Las Vegas' current water reclamation and reuse strategies using a case study framework to examine policy and reclamation technology issues in urban areas; and (ii) using this case study, develop general recommendations and best practices to guide the implementation of water reclamation technologies in the U.S. To accomplish these goals, the committee assessed: (i) the state of the art in water reclamation; (ii) how water management issues and the role of water reclamation are framed in Las Vegas; (iii) the perspectives and alignment of different groups of stakeholders involved in water management issues; and (iv) reclamation technology and policy interactions with respect to public perception, health, environment, regulation and incentives, and security issues

Cyber Infrastructure Protection: Vol. II

View the Executive SummaryIncreased reliance on the Internet and other networked systems raise the risks of cyber attacks that could harm our nation’s cyber infrastructure. The cyber infrastructure encompasses a number of sectors including: the nation’s mass transit and other transportation systems; banking and financial systems; factories; energy systems and the electric power grid; and telecommunications, which increasingly rely on a complex array of computer networks, including the public Internet. However, many of these systems and networks were not built and designed with security in mind. Therefore, our cyber infrastructure contains many holes, risks, and vulnerabilities that may enable an attacker to cause damage or disrupt cyber infrastructure operations. Threats to cyber infrastructure safety and security come from hackers, terrorists, criminal groups, and sophisticated organized crime groups; even nation-states and foreign intelligence services conduct cyber warfare. Cyber attackers can introduce new viruses, worms, and bots capable of defeating many of our efforts. Costs to the economy from these threats are huge and increasing. Government, business, and academia must therefore work together to understand the threat and develop various modes of fighting cyber attacks, and to establish and enhance a framework to assess the vulnerability of our cyber infrastructure and provide strategic policy directions for the protection of such an infrastructure. This book addresses such questions as: How serious is the cyber threat? What technical and policy-based approaches are best suited to securing telecommunications networks and information systems infrastructure security? What role will government and the private sector play in homeland defense against cyber attacks on critical civilian infrastructure, financial, and logistical systems? What legal impediments exist concerning efforts to defend the nation against cyber attacks, especially in preventive, preemptive, and retaliatory actions?https://press.armywarcollege.edu/monographs/1527/thumbnail.jp