Generation of density inhomogeneities by magnetohydrodynamic waves in two dimensions

Using two dimensional simulations, we study the formation of structures with a high-density contrast by magnetohydrodynamic waves in regions in which the ratio of thermal to magnetic pressure is small. The initial state is a uniform background perturbed by fast-mode wave. Our most significant result is that dense structures persist for far longer in a two-dimensional simulation than in the one-dimensional case. Once formed, these structures persist as long as the fast-mode amplitude remains high.Comment: 6 pages, 7 figures, accepted by MNRA

Mass transfer characteristics in structured packing for CO2 emission reduction processes

Acid gas treating and CO2 capture from flue gas by absorption have gained wide importance over the past few decades. With the implementation of more stringent environmental regulations and the awareness of the greenhouse effect, the need for efficient removal of acid gases such as CO2 (carbon dioxide) has increased significantly. Therefore, additional effort for research in this field is inevitable. For flue gas processes the ratio of absorption solvent to gas throughput is very different compared to acid gas treating processes owing to the atmospheric pressures and the dilution effect of combustion air. Moreover, in flue gas applications pressure drop is a very important process parameter. Packing types are required that allow for low pressure drop in combination with high interfacial areas at low liquid loading per square meter. The determination of interfacial areas in gas-liquid contactors by means of the chemical method (Danckwerts, P. V. Gas-liquid reactions; McGraw-Hill: London, 1970) has been very frequently applied. Unfortunately, many of the model systems proposed in the literature are reversible and therefore this condition possibly is not met. Versteeg et al. (Versteeg, G. F.; Kuipers, J. A. M.; Beckum, F. P. H.; van Swaaij, W. P. M. Chem. Eng. Sci. 1989, 44, 2292) have demonstrated that for reversible reactions the conditions for the determination of the interfacial area by means of the chemical method are much more severe. In a study by Raynal et al. (Raynal, L.; Ballaguet, J. P.; Berrere-Tricca, C. Chem. Eng. Sci. 2004, 59, 5395), it has been shown that there is a dependency of the interfacial area on the packing height. Unfortunately, most model systems used, e.g., CO2-caustic soda (as used by Raynal et al.), are much more complex and consist of (a set of) reversible reaction(s). The natures of these systems make the conditions at which the interfacial area can be determined much more severe and put more limitations on the process conditions and experimental equipment than a priori can be expected. Therefore, an extended absorption model is required to determine the conditions at which the interfacial area can be measured without detailed knowledge of the values of the liquid-side mass transfer coefficient, k1, beforehand.

Formal verification and analysis of primary authentication based on 5G-AKA protocol

Fifth generation mobile network (5G) is intended to solve future constraints for accessing network services. The user and network operator depend on security assurances provided by the Authentication and Key Agreement protocols (AKA) used. For 5G network, the AKA has been standardized and 5GAKA protocol is one of the primary authentication methods that have been defined. This paper models the protocol and provides comprehensive formal analysis on 5G-AKA protocol as specified by The Third Generation Partnership Project (3GPP) standard. Using ProVerif a security protocol verification tool, we perform a full systematic evaluation of the 5G-AKA protocol based on the latest 5G specifications. We present security assumptions and properties that assists on the analysis based on two taxonomies, we find out that some important security properties are not achieved and related work ignored some crucial protocol flaws. Finally, we make some recommendations to address the issues found by our security analysis

Formalization and evaluation of EAP-AKA’ protocol for 5G network access security

The end user’s Quality of Experience (QoE) will be improved while accessing services in Fifth Generation Mobile Network (5G), supported by enhanced security and privacy. The security guarantees offered by the Authentication and Key Agreement (AKA) protocols will be depended upon by end users and network operators. The AKA protocols have been standardized for 5G networks, and the Extensible Authentication Protocol (EAP)-AKA’ protocol is one of the main authentication mechanisms that has been specified for User Equipment (UE) and network mutual authentication. This article models the EAP-AKA’ protocol and conducts an extensive formal verification of the EAP-AKA’ protocol as defined in the 5G security standard to determine whether the protocol is verifiably secure for 5G. It provides a security evaluation of the EAP–AKA’ protocol based on the current 5G specifications using ProVerif, a security protocol proof verifier. It also presents security properties that support the security verification, as well as quantitative properties that are used to assess the protocol’s performance. Finally, it compares the EAP-AKA’ and 5G-AKA protocols’ security and performance results

Fabrication of high efficiency and radiation resistant GaAs solar cells

Systematic improvements in fabrication yield were obtained by appropriate control of the liquid phase epitaxial growth process, contact fabrication and surface preparation. To improve radiation hardness, the junction depth was decreased while overcoming the penalty in decreased solar cell efficiency which tends to go hand-in-hand with the reduction of junction depth in (AlGa) As-GaAs solar cells. Cells were made with an AMO efficiency of 18% and a junction depth of 0.5 micrometers, as compared to junction depths on the order of 1.0 micrometers. With respect to the damage caused by proton irradiation, the nature of the observed damage was correlated to the energy and penetration depth of the damaging protons

The case for federated identity management in 5G communications

The heterogeneous nature of fifth generation mobile network (5G) makes the access and provision of network services very difficult and raises security concerns. With multi-users and multi-operators, Service-Oriented Authentication (SOA) and authorization mechanisms are required to provide quick access and interaction between network services. The users require seamless access to services regardless of the domain, type of connectivity or security mechanism used. Hence a need for Identity and Access Management (IAM) mechanism to complement the improved user experience promised in 5G. Federated Identity Management (FIdM) a feature of IAM, can provide a user with use Single Sign On (SSO) to access services from multiple Service Providers (SP). This addresses security requirements such as authentication, authorization and user’s privacy from the end user perspectives, however 5G networks access lacks such solution. We propose a Network Service Federated Identity (NS-FId) model that address these security requirements and complements the 5G Service- Based Architecture (SBA). We present different scenarios and applications of the proposed model. We also discuss the benefits of identity management in 5G

Investigating network services abstraction in 5G enabled device-to-device (D2D) communications

The increased demand of data rate by mobile users has led to the evolution of mobile network technologies from the fourth generation to fifth generation (5G). 5G mobile network will support various technologies that will be able to provide low latency, offload traffic and connect vertical industries. Device-to-device (D2D) communications will be used as the underlay technology for 5G network in the offloading of traffic from the cellular network and pushing content closer to the user. With D2D communication, various network services can be implemented to improve spectral efficiency and reduce energy consumption of mobile devices. This paper gives a brief overview of D2D communication and discusses different D2D applications. It proposes a network services abstraction and suggests the mapping of existing studies with the network service abstraction which can be used in the harnessing the development and implementation of D2D communication applications in 5G network. The paper also highlights possible future research for D2D communication in 5G network

An introduction of a modular framework for securing 5G networks and beyond

Fifth Generation Mobile Network (5G) is a heterogeneous network in nature, made up of multiple systems and supported by different technologies. It will be supported by network services such as device-to-device (D2D) communications. This will enable the new use cases to provide access to other services within the network and from third-party service providers (SPs). End-users with their user equipment (UE) will be able to access services ubiquitously from multiple SPs that might share infrastructure and security management, whereby implementing security from one domain to another will be a challenge. This highlights a need for a new and effective security approach to address the security of such a complex system. This article proposes a network service security (NSS) modular framework for 5G and beyond that consists of different security levels of the network. It reviews the security issues of D2D communications in 5G, and it is used to address security issues that affect the users and SPs in an integrated and heterogeneous network such as the 5G enabled D2D communications network. The conceptual framework consists of a physical layer, network access, service and D2D security levels. Finally, it recommends security mechanisms to address the security issues at each level of the 5G-enabled D2D communications network

Network service federated identity (NS-FId) protocol for service authorization in 5G network

Fifth generation mobile network (5G) will make network services available anywhere from multiple Service Providers (SP) and its provisioning raises security concerns. The users will require seamless connectivity and secure access to these services. Mobile Network Operator (MNO) will want to provide services to users and be able to share infrastructure resources with other MNOs. This requires robust authentication and authorization mechanisms that can provide secure access and provisioning of service to multiple users and providers in heterogeneous network. Therefore, Federated Identity (FId) with Single Sign On (SSO) could be used for seamless access and provisioning to network services in 5G. So, we propose Network Service Federated Identity (NS-FId) protocol, a federated protocol that provides secure access to services from multiple SPs and provides SSO to users. We formally verify and analyse the proposed NSFId protocol using ProVerif. We also conduct a security analysis of the protocol’s security properties

DCSS protocol for data caching and sharing security in a 5G network

Fifth Generation mobile networks (5G) promise to make network services provided by various Service Providers (SP) such as Mobile Network Operators (MNOs) and third-party SPs accessible from anywhere by the end-users through their User Equipment (UE). These services will be pushed closer to the edge for quick, seamless, and secure access. After being granted access to a service, the end-user will be able to cache and share data with other users. However, security measures should be in place for SP not only to secure the provisioning and access of those services but also, should be able to restrict what the end-users can do with the accessed data in or out of coverage. This can be facilitated by federated service authorization and access control mechanisms that restrict the caching and sharing of data accessed by the UE in different security domains. In this paper, we propose a Data Caching and Sharing Security (DCSS) protocol that leverages federated authorization to provide secure caching and sharing of data from multiple SPs in multiple security domains. We formally verify the proposed DCSS protocol using ProVerif and applied pi-calculus. Furthermore, a comprehensive security analysis of the security properties of the proposed DCSS protocol is conducted