Recently, the fog computing concept has been introduced into vehicular ad-hoc networks (VANETs) to formulate fog-based VANETs. Since the communication channels between vehicles and fog nodes are open and insecure, it is necessary to construct an authenticated key agreement (AKA) scheme for securing the channels. The existing AKA schemes have two main deficiencies. One is that the computational and communication overhead are not low enough to satisfy the requirements of delay-sensitive applications. The other is that the multi-trustedauthority (multi-TA) model has not been considered. To solve the deficiencies, we propose a lightweight and conditional privacypreserving AKA scheme, where the main steps are designed with symmetric cryptography methods. The design can reduce the computational and communication overhead of the AKA process. Additionally, we consider the multi-TA model in the AKA process to solve the single-point-of-failure issue. By integrating Cuckoo filter into the multi-TA model, the secrecy of real identities of legal vehicles is guaranteed and the identity revocation function for illegal vehicles is supported in the AKA process. The security proof and analysis show that our proposed scheme satisfies the essential security and privacy requirements of VANETs. The performance analysis shows that our proposed scheme outperforms other related and represented schemes.
Drones (or unmanned aerial vehicles) can play many assistant roles in the complex communication network and can be used as an air relay node to support ground communications. It is expected to solve the sustainable communication problem of 5G/ beyond 5G (B5G) vehicular ad-hoc networks by using drones in rural or mountainous areas where communication is limited. In this paper, considering the emergency of vehicular ad-hoc networks, we design an assistant communication scheme based on the intelligent drone to help vehicles securely communicate with each other under adversary but actual conditions. Besides, the real identity of the vehicle must also be protected to prevent illegal elements from obtaining and using them for crimes. To effectively assist vehicle communication and ensure that vehicle privacy is not compromised, we propose an intelligent drone-assisted anonymous authentication and key agreement for 5G/B5G vehicular ad-hoc networks. Utilizing the widely-used Real-Or-Random (ROR) model and the formal security analysis, the proposed scheme is proven to be resistant to several attacks. Moreover, the proposed scheme has better performance in terms of computation overhead and communication overhead through performance evaluation.
The objective of the present study was to assess hair trace element content in Hereford heifers and cows (Bos taurus) living in South Ural region and calculate the site-specific reference intervals. Hair trace element content in 150 cows and heifers farmed in the Southern Urals of Russia was assessed using inductively coupled plasma mass-spectrometry. Dietary trace element content corresponded to the adequate values as estimated by recommendations of USSR State Agriculture Committee and U.S. National Research Council. Comparative analysis demonstrated that heifers are characterized by significantly higher hair Se (3-fold), Hg (4-fold), and Sn (46%) content, whereas cows had significantly higher levels of hair Co (56%), I (33%), Si (2-fold), V (27%), B (55%), Cd (19%), Pb (47%), and Sr (23%). At the same time, no significant group difference in hair Cr, Cu, Fe, Li, Mn, Zn, As, and Ni was detected between Hereford cows and heifers. The reference intervals and 90% confidence intervals for the lower and upper limits were calculated in agreement with the American Society for Veterinary Clinical Pathology Quality Assurance and Laboratory Standard Guidelines.
The work is devoted to the problem of mathematical modeling and search for optimal control of the dynamics of the insulin-glucose balance in human blood, represented by a nonsmooth sys-tem of differential equations with a constant delay. Aim. This study is aimed at developing and numerically solving the problem of optimal control of the glycemic profile in patients with type 1 di-abetes mel¬litus by insulin therapy, based on the optimality conditions for nonsmooth systems with a constant delay in the phase variable. Methods. The general research technique of the problem under study is based on the mathematical theory of optimal control, the theory of numerical methods, the theory of differential equations with a nonsmooth right-hand side and with a lagging argument. When implementing the software package, the methods of object-oriented design are used. Results. In this study, on the basis of the initial dynamic model proposed by N.A. Shirokova, the problem of optimal control of the dynamics of glycemic regulation in patients with type 1 diabetes mellitus with a non¬smooth right side and a constant delay in the phase variable is constructed. On the basis of the necessary optimality condition obtained for the constructed optimal control problem, algorithmic and software tools have been developed, with the help of which optimal programs are obtained, and their meaningful interpretation is presented. Conclusion. The results obtained on the basis of the software implementation of numerical algorithms of the developed nonsmooth problem of optimal control of the insulin-glucose balance with a constant lag in the phase variables, make it possible to obtain the data that are necessary for monitoring the situation regarding the change in the glycemic profile, for predicting diabetes mellitus and choosing an effective treatment.
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